*** empty log message ***
[mono.git] / mcs / mcs / expression.cs
index 05f15941b079b0846613d658d3c4ef3c037b51eb..47062869ba4d7debd08537c82e3f4ba17dfd3f9d 100755 (executable)
 //
 // (C) 2001 Ximian, Inc.
 //
+//
+// Ideas:
+//   Maybe we should make Resolve be an instance method that just calls
+//   the virtual DoResolve function and checks conditions like the eclass
+//   and type being set if a non-null value is returned.  For robustness
+//   purposes.
+//
+
 namespace CIR {
+       using System;
        using System.Collections;
        using System.Diagnostics;
-       using System;
+       using System.Reflection;
+       using System.Reflection.Emit;
+       using System.Text;
        
-       public abstract class Expression {
-               string type;
-               bool is_lvalue;
+       // <remarks>
+       //   The ExprClass class contains the is used to pass the 
+       //   classification of an expression (value, variable, namespace,
+       //   type, method group, property access, event access, indexer access,
+       //   nothing).
+       // </remarks>
+       public enum ExprClass {
+               Invalid,
+               
+               Value,
+               Variable,   // Every Variable should implement LValue
+               Namespace,
+               Type,
+               MethodGroup,
+               PropertyAccess,
+               EventAccess,
+               IndexerAccess,
+               Nothing, 
+       }
 
-               public string Type {
+       // <remarks>
+       //   Base class for expressions
+       // </remarks>
+       public abstract class Expression {
+               protected ExprClass eclass;
+               protected Type      type;
+               
+               public Type Type {
                        get {
                                return type;
                        }
+
+                       set {
+                               type = value;
+                       }
                }
 
-               public bool IsLValue {
+               public ExprClass ExprClass {
                        get {
-                               return is_lvalue;
+                               return eclass;
                        }
 
                        set {
-                               is_lvalue = value;
+                               eclass = value;
                        }
                }
 
-               public virtual bool IsLiteral {
-                       get {
-                               return false;
+               // <summary>
+               //   Utility wrapper routine for Error, just to beautify the code
+               // </summary>
+               static protected void Error (TypeContainer tc, int error, string s)
+               {
+                       tc.RootContext.Report.Error (error, s);
+               }
+
+               static protected void Error (TypeContainer tc, int error, Location l, string s)
+               {
+                       tc.RootContext.Report.Error (error, l, s);
+               }
+               
+               // <summary>
+               //   Utility wrapper routine for Warning, just to beautify the code
+               // </summary>
+               static protected void Warning (TypeContainer tc, int warning, string s)
+               {
+                       tc.RootContext.Report.Warning (warning, s);
+               }
+
+               // <summary>
+               //   Performs semantic analysis on the Expression
+               // </summary>
+               //
+               // <remarks>
+               //   The Resolve method is invoked to perform the semantic analysis
+               //   on the node.
+               //
+               //   The return value is an expression (it can be the
+               //   same expression in some cases) or a new
+               //   expression that better represents this node.
+               //   
+               //   For example, optimizations of Unary (LiteralInt)
+               //   would return a new LiteralInt with a negated
+               //   value.
+               //   
+               //   If there is an error during semantic analysis,
+               //   then an error should
+               //   be reported (using TypeContainer.RootContext.Report) and a null
+               //   value should be returned.
+               //   
+               //   There are two side effects expected from calling
+               //   Resolve(): the the field variable "eclass" should
+               //   be set to any value of the enumeration
+               //   `ExprClass' and the type variable should be set
+               //   to a valid type (this is the type of the
+               //   expression).
+               // </remarks>
+               
+               public abstract Expression DoResolve (TypeContainer tc);
+
+
+               //
+               // Currently Resolve wraps DoResolve to perform sanity
+               // checking and assertion checking on what we expect from Resolve
+               //
+
+               public Expression Resolve (TypeContainer tc)
+               {
+                       Expression e = DoResolve (tc);
+
+                       if (e != null){
+                               if (e.ExprClass == ExprClass.Invalid)
+                                       throw new Exception ("Expression " + e +
+                                                            " ExprClass is Invalid after resolve");
+
+                               if (e.ExprClass != ExprClass.MethodGroup)
+                                       if (e.type == null)
+                                               throw new Exception ("Expression " + e +
+                                                                    " did not set its type after Resolve");
                        }
+
+                       return e;
                }
+                      
+               // <summary>
+               //   Emits the code for the expression
+               // </summary>
+               //
+               // <remarks>
+               // 
+               //   The Emit method is invoked to generate the code
+               //   for the expression.  
+               //
+               // </remarks>
+               public abstract void Emit (EmitContext ec);
                
                // <summary>
                //   Protected constructor.  Only derivate types should
                //   be able to be created
                // </summary>
-               // protected Type (
 
                protected Expression ()
                {
+                       eclass = ExprClass.Invalid;
                        type = null;
                }
-               
-               static bool EvaluateType (Expression expr, out string setType)
+
+               // <summary>
+               //   Returns a literalized version of a literal FieldInfo
+               // </summary>
+               static Expression Literalize (FieldInfo fi)
                {
-                       setType = null;
-                       return true;
+                       Type t = fi.FieldType;
+                       object v = fi.GetValue (fi);
+
+                       if (t == TypeManager.int32_type)
+                               return new IntLiteral ((int) v);
+                       else if (t == TypeManager.uint32_type)
+                               return new UIntLiteral ((uint) v);
+                       else if (t == TypeManager.int64_type)
+                               return new LongLiteral ((long) v);
+                       else if (t == TypeManager.uint64_type)
+                               return new ULongLiteral ((ulong) v);
+                       else if (t == TypeManager.float_type)
+                               return new FloatLiteral ((float) v);
+                       else if (t == TypeManager.double_type)
+                               return new DoubleLiteral ((double) v);
+                       else if (t == TypeManager.string_type)
+                               return new StringLiteral ((string) v);
+                       else if (t == TypeManager.short_type)
+                               return new IntLiteral ((int) ((short)v));
+                       else if (t == TypeManager.ushort_type)
+                               return new IntLiteral ((int) ((ushort)v));
+                       else if (t == TypeManager.sbyte_type)
+                               return new IntLiteral ((int) ((sbyte)v));
+                       else if (t == TypeManager.byte_type)
+                               return new IntLiteral ((int) ((byte)v));
+                       else if (t == TypeManager.char_type)
+                               return new IntLiteral ((int) ((char)v));
+                       else
+                               throw new Exception ("Unknown type for literal (" + v.GetType () +
+                                                    "), details: " + fi);
                }
-       }
 
-       public class Unary : Expression {
-               public enum Operator {
-                       Plus, Minus, Negate, BitComplement,
-                       Indirection, AddressOf, PreIncrement,
-                       PreDecrement, PostIncrement, PostDecrement
+               // 
+               // Returns a fully formed expression after a MemberLookup
+               //
+               static Expression ExprClassFromMemberInfo (TypeContainer tc, MemberInfo mi)
+               {
+                       if (mi is EventInfo){
+                               return new EventExpr ((EventInfo) mi);
+                       } else if (mi is FieldInfo){
+                               FieldInfo fi = (FieldInfo) mi;
+
+                               if (fi.IsLiteral){
+                                       Expression e = Literalize (fi);
+                                       e.Resolve (tc);
+
+                                       return e;
+                               } else
+                                       return new FieldExpr (fi);
+                       } else if (mi is PropertyInfo){
+                               return new PropertyExpr ((PropertyInfo) mi);
+                       } else if (mi is Type)
+                               return new TypeExpr ((Type) mi);
+
+                       return null;
+               }
+               
+               //
+               // FIXME: Probably implement a cache for (t,name,current_access_set)?
+               //
+               // FIXME: We need to cope with access permissions here, or this wont
+               // work!
+               //
+               // This code could use some optimizations, but we need to do some
+               // measurements.  For example, we could use a delegate to `flag' when
+               // something can not any longer be a method-group (because it is something
+               // else).
+               //
+               // Return values:
+               //     If the return value is an Array, then it is an array of
+               //     MethodBases
+               //   
+               //     If the return value is an MemberInfo, it is anything, but a Method
+               //
+               //     null on error.
+               //
+               // FIXME: When calling MemberLookup inside an `Invocation', we should pass
+               // the arguments here and have MemberLookup return only the methods that
+               // match the argument count/type, unlike we are doing now (we delay this
+               // decision).
+               //
+               // This is so we can catch correctly attempts to invoke instance methods
+               // from a static body (scan for error 120 in ResolveSimpleName).
+               //
+               public static Expression MemberLookup (TypeContainer tc, Type t, string name,
+                                                      bool same_type, MemberTypes mt, BindingFlags bf)
+               {
+                       if (same_type)
+                               bf |= BindingFlags.NonPublic;
+
+                       MemberInfo [] mi = tc.RootContext.TypeManager.FindMembers (
+                               t, mt, bf, Type.FilterName, name);
+
+                       if (mi == null)
+                               return null;
+                       
+                       if (mi.Length == 1 && !(mi [0] is MethodBase))
+                               return Expression.ExprClassFromMemberInfo (tc, mi [0]);
+                       
+                       for (int i = 0; i < mi.Length; i++)
+                               if (!(mi [i] is MethodBase)){
+                                       Error (tc,
+                                              -5, "Do not know how to reproduce this case: " + 
+                                              "Methods and non-Method with the same name, " +
+                                              "report this please");
+
+                                       for (i = 0; i < mi.Length; i++){
+                                               Type tt = mi [i].GetType ();
+
+                                               Console.WriteLine (i + ": " + mi [i]);
+                                               while (tt != TypeManager.object_type){
+                                                       Console.WriteLine (tt);
+                                                       tt = tt.BaseType;
+                                               }
+                                       }
+                               }
+
+                       return new MethodGroupExpr (mi);
                }
 
-               Operator   oper;
-               Expression expr;
+               public const MemberTypes AllMemberTypes =
+                       MemberTypes.Constructor |
+                       MemberTypes.Event       |
+                       MemberTypes.Field       |
+                       MemberTypes.Method      |
+                       MemberTypes.NestedType  |
+                       MemberTypes.Property;
                
-               public Unary (Operator op, Expression expr)
+               public const BindingFlags AllBindingsFlags =
+                       BindingFlags.Public |
+                       BindingFlags.Static |
+                       BindingFlags.Instance;
+
+               public static Expression MemberLookup (TypeContainer tc, Type t, string name,
+                                                      bool same_type)
                {
-                       this.oper = op;
-                       this.expr = expr;
+                       return MemberLookup (tc, t, name, same_type, AllMemberTypes, AllBindingsFlags);
                }
 
-               public Expression Expr {
-                       get {
-                               return expr;
+               //
+               // I am in general unhappy with this implementation.
+               //
+               // I need to revise this.
+               //
+               static public Expression ResolveMemberAccess (TypeContainer tc, string name)
+               {
+                       Expression left_e = null;
+                       int dot_pos = name.LastIndexOf (".");
+                       string left = name.Substring (0, dot_pos);
+                       string right = name.Substring (dot_pos + 1);
+                       Type t;
+
+                       if ((t = tc.LookupType (left, false)) != null){
+                               Expression e;
+                               
+                               left_e = new TypeExpr (t);
+                               e = new MemberAccess (left_e, right);
+                               return e.Resolve (tc);
+                       } else {
+                               //
+                               // FIXME: IMplement:
+                               
+                               // Handle here:
+                               //    T.P  Static property access (P) on Type T.
+                               //    e.P  instance property access on instance e for P.
+                               //    p
+                               //
                        }
 
-                       set {
-                               expr = value;
+                       if (left_e == null){
+                               Error (tc, 246, "Can not find type or namespace `"+left+"'");
+                               return null;
+                       }
+
+                       switch (left_e.ExprClass){
+                       case ExprClass.Type:
+                               return  MemberLookup (tc,
+                                                     left_e.Type, right,
+                                                     left_e.Type == tc.TypeBuilder);
+                               
+                       case ExprClass.Namespace:
+                       case ExprClass.PropertyAccess:
+                       case ExprClass.IndexerAccess:
+                       case ExprClass.Variable:
+                       case ExprClass.Value:
+                       case ExprClass.Nothing:
+                       case ExprClass.EventAccess:
+                       case ExprClass.MethodGroup:
+                       case ExprClass.Invalid:
+                               throw new Exception ("Should have got the " + left_e.ExprClass +
+                                                    " handled before");
                        }
+                       
+                       return null;
                }
 
-               public Operator Oper {
-                       get {
-                               return oper;
+               static public Expression ImplicitReferenceConversion (Expression expr, Type target_type)
+               {
+                       Type expr_type = expr.Type;
+
+                       if (target_type == TypeManager.object_type) {
+                               if (expr_type.IsClass)
+                                       return new EmptyCast (expr, target_type);
+                               if (expr_type.IsValueType)
+                                       return new BoxedCast (expr);
+                       } else if (expr_type.IsSubclassOf (target_type)) {
+                               return new EmptyCast (expr, target_type);
+                       } else {
+                               // from any class-type S to any interface-type T.
+                               if (expr_type.IsClass && target_type.IsInterface) {
+                                       Type [] interfaces = expr_type.FindInterfaces (Module.FilterTypeName,
+                                                                                      target_type.FullName);
+                                       if (interfaces != null)
+                                               return new EmptyCast (expr, target_type);
+                               }       
+
+                               // from any interface type S to interface-type T.
+                               // FIXME : Is it right to use IsAssignableFrom ?
+                               if (expr_type.IsInterface && target_type.IsInterface)
+                                       if (target_type.IsAssignableFrom (expr_type))
+                                               return new EmptyCast (expr, target_type);
+                               
+                               
+                               // from an array-type S to an array-type of type T
+                               if (expr_type.IsArray && target_type.IsArray) {
+                                       
+                                       throw new Exception ("Implement array conversion");
+                                       
+                               }
+                               
+                               // from an array-type to System.Array
+                               if (expr_type.IsArray && target_type.IsAssignableFrom (expr_type))
+                                       return new EmptyCast (expr, target_type);
+                               
+                               // from any delegate type to System.Delegate
+                               if (expr_type.IsSubclassOf (TypeManager.delegate_type) &&
+                                   target_type == TypeManager.delegate_type)
+                                       if (target_type.IsAssignableFrom (expr_type))
+                                               return new EmptyCast (expr, target_type);
+                                       
+                               // from any array-type or delegate type into System.ICloneable.
+                               if (expr_type.IsArray || expr_type.IsSubclassOf (TypeManager.delegate_type))
+                                       if (target_type == TypeManager.cloneable_interface)
+                                               throw new Exception ("Implement conversion to System.ICloneable");
+                               
+                               // from the null type to any reference-type.
+                               // FIXME : How do we do this ?
+
+                               return null;
+
                        }
+                       
+                       return null;
+               }
 
-                       set {
-                               oper = value;
+               // <summary>
+               //   Handles expressions like this: decimal d; d = 1;
+               //   and changes them into: decimal d; d = new System.Decimal (1);
+               // </summary>
+               static Expression InternalTypeConstructor (TypeContainer tc, Expression expr, Type target)
+               {
+                       ArrayList args = new ArrayList ();
+
+                       args.Add (new Argument (expr, Argument.AType.Expression));
+
+                       Expression ne = new New (target.FullName, args,
+                                                new Location (-1));
+
+                       return ne.Resolve (tc);
+               }
+
+               // <summary>
+               //   Implicit Numeric Conversions.
+               //
+               //   expr is the expression to convert, returns a new expression of type
+               //   target_type or null if an implicit conversion is not possible.
+               //
+               // </summary>
+               static public Expression ImplicitNumericConversion (TypeContainer tc, Expression expr,
+                                                                   Type target_type, Location l)
+               {
+                       Type expr_type = expr.Type;
+                       
+                       //
+                       // Attempt to do the implicit constant expression conversions
+
+                       if (expr is IntLiteral){
+                               Expression e;
+                               
+                               e = TryImplicitIntConversion (target_type, (IntLiteral) expr);
+                               if (e != null)
+                                       return e;
+                       } else if (expr is LongLiteral){
+                               //
+                               // Try the implicit constant expression conversion
+                               // from long to ulong, instead of a nice routine,
+                               // we just inline it
+                               //
+                               if (((LongLiteral) expr).Value > 0)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                       }
+                       
+                       if (expr_type == TypeManager.sbyte_type){
+                               //
+                               // From sbyte to short, int, long, float, double.
+                               //
+                               if (target_type == TypeManager.int32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
+                               if (target_type == TypeManager.int64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                               if (target_type == TypeManager.double_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
+                               if (target_type == TypeManager.float_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
+                               if (target_type == TypeManager.short_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
+                               if (target_type == TypeManager.decimal_type)
+                                       return InternalTypeConstructor (tc, expr, target_type);
+                       } else if (expr_type == TypeManager.byte_type){
+                               //
+                               // From byte to short, ushort, int, uint, long, ulong, float, double
+                               // 
+                               if ((target_type == TypeManager.short_type) ||
+                                   (target_type == TypeManager.ushort_type) ||
+                                   (target_type == TypeManager.int32_type) ||
+                                   (target_type == TypeManager.uint32_type))
+                                       return new EmptyCast (expr, target_type);
+
+                               if (target_type == TypeManager.uint64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
+                               if (target_type == TypeManager.int64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                               
+                               if (target_type == TypeManager.float_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
+                               if (target_type == TypeManager.double_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
+                               if (target_type == TypeManager.decimal_type)
+                                       return InternalTypeConstructor (tc, expr, target_type);
+                       } else if (expr_type == TypeManager.short_type){
+                               //
+                               // From short to int, long, float, double
+                               // 
+                               if (target_type == TypeManager.int32_type)
+                                       return new EmptyCast (expr, target_type);
+                               if (target_type == TypeManager.int64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                               if (target_type == TypeManager.double_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
+                               if (target_type == TypeManager.float_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
+                               if (target_type == TypeManager.decimal_type)
+                                       return InternalTypeConstructor (tc, expr, target_type);
+                       } else if (expr_type == TypeManager.ushort_type){
+                               //
+                               // From ushort to int, uint, long, ulong, float, double
+                               //
+                               if (target_type == TypeManager.uint32_type)
+                                       return new EmptyCast (expr, target_type);
+
+                               if (target_type == TypeManager.uint64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
+                               if (target_type == TypeManager.int32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
+                               if (target_type == TypeManager.int64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                               if (target_type == TypeManager.double_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
+                               if (target_type == TypeManager.float_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
+                               if (target_type == TypeManager.decimal_type)
+                                       return InternalTypeConstructor (tc, expr, target_type);
+                       } else if (expr_type == TypeManager.int32_type){
+                               //
+                               // From int to long, float, double
+                               //
+                               if (target_type == TypeManager.int64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                               if (target_type == TypeManager.double_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
+                               if (target_type == TypeManager.float_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
+                               if (target_type == TypeManager.decimal_type)
+                                       return InternalTypeConstructor (tc, expr, target_type);
+                       } else if (expr_type == TypeManager.uint32_type){
+                               //
+                               // From uint to long, ulong, float, double
+                               //
+                               if (target_type == TypeManager.int64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
+                               if (target_type == TypeManager.uint64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
+                               if (target_type == TypeManager.double_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
+                                                              OpCodes.Conv_R8);
+                               if (target_type == TypeManager.float_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
+                                                              OpCodes.Conv_R4);
+                               if (target_type == TypeManager.decimal_type)
+                                       return InternalTypeConstructor (tc, expr, target_type);
+                       } else if ((expr_type == TypeManager.uint64_type) ||
+                                  (expr_type == TypeManager.int64_type)){
+                               //
+                               // From long/ulong to float, double
+                               //
+                               if (target_type == TypeManager.double_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
+                                                              OpCodes.Conv_R8);
+                               if (target_type == TypeManager.float_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
+                                                              OpCodes.Conv_R4);        
+                               if (target_type == TypeManager.decimal_type)
+                                       return InternalTypeConstructor (tc, expr, target_type);
+                       } else if (expr_type == TypeManager.char_type){
+                               //
+                               // From char to ushort, int, uint, long, ulong, float, double
+                               // 
+                               if ((target_type == TypeManager.ushort_type) ||
+                                   (target_type == TypeManager.int32_type) ||
+                                   (target_type == TypeManager.uint32_type))
+                                       return new EmptyCast (expr, target_type);
+                               if (target_type == TypeManager.uint64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
+                               if (target_type == TypeManager.int64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                               if (target_type == TypeManager.float_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
+                               if (target_type == TypeManager.double_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
+                               if (target_type == TypeManager.decimal_type)
+                                       return InternalTypeConstructor (tc, expr, target_type);
+                       } else if (expr_type == TypeManager.float_type){
+                               //
+                               // float to double
+                               //
+                               if (target_type == TypeManager.double_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
+                       }
+
+                       return null;
+               }
+
+               // <summary>
+               //   User-defined implicit conversions
+               // </summary>
+               static public Expression ImplicitUserConversion (TypeContainer tc, Expression source,
+                                                                Type target, Location l)
+               {
+                       Expression mg1, mg2;
+                       MethodBase method;
+                       ArrayList arguments;
+                       
+                       mg1 = MemberLookup (tc, source.Type, "op_Implicit", false);
+                       mg2 = MemberLookup (tc, target, "op_Implicit", false);
+                       
+                       MethodGroupExpr union = Invocation.MakeUnionSet (mg1, mg2);
+
+                       if (union != null) {
+                               arguments = new ArrayList ();
+                               arguments.Add (new Argument (source, Argument.AType.Expression));
+
+                               method = Invocation.OverloadResolve (tc, union, arguments, l, true);
+
+                               if (method != null) { 
+                                       MethodInfo mi = (MethodInfo) method;
+                                       
+                                       if (mi.ReturnType == target)
+                                               return new UserImplicitCast (mi, arguments);
+                               }
+                       }
+                       
+                       // If we have a boolean type, we need to check for the True
+                       // and False operators too.
+                       
+                       if (target == TypeManager.bool_type) {
+
+                               mg1 = MemberLookup (tc, source.Type, "op_True", false);
+                               mg2 = MemberLookup (tc, target, "op_True", false);
+                               
+                               union = Invocation.MakeUnionSet (mg1, mg2);
+
+                               if (union == null)
+                                       return null;
+
+                               arguments = new ArrayList ();
+                               arguments.Add (new Argument (source, Argument.AType.Expression));
+                       
+                               method = Invocation.OverloadResolve (tc, union, arguments, l, true);
+                               if (method != null) {
+                                       MethodInfo mi = (MethodInfo) method;
+
+                                       if (mi.ReturnType == target) 
+                                               return new UserImplicitCast (mi, arguments);
+                               }
+                       }
+                       
+                       return null;
+               }
+               
+               // <summary>
+               //   Converts implicitly the resolved expression `expr' into the
+               //   `target_type'.  It returns a new expression that can be used
+               //   in a context that expects a `target_type'. 
+               // </summary>
+               static public Expression ConvertImplicit (TypeContainer tc, Expression expr,
+                                                         Type target_type, Location l)
+               {
+                       Type expr_type = expr.Type;
+                       Expression e;
+
+                       if (expr_type == target_type)
+                               return expr;
+
+                       e = ImplicitNumericConversion (tc, expr, target_type, l);
+                       if (e != null)
+                               return e;
+
+                       e = ImplicitReferenceConversion (expr, target_type);
+                       if (e != null)
+                               return e;
+
+                       e = ImplicitUserConversion (tc, expr, target_type, l);
+                       if (e != null)
+                               return e;
+
+                       if (target_type.IsSubclassOf (TypeManager.enum_type) && expr is IntLiteral){
+                               IntLiteral i = (IntLiteral) expr;
+
+                               if (i.Value == 0)
+                                       return new EmptyCast (expr, target_type);
+                       }
+                       return null;
+               }
+
+               
+               // <summary>
+               //   Attempts to apply the `Standard Implicit
+               //   Conversion' rules to the expression `expr' into
+               //   the `target_type'.  It returns a new expression
+               //   that can be used in a context that expects a
+               //   `target_type'.
+               //
+               //   This is different from `ConvertImplicit' in that the
+               //   user defined implicit conversions are excluded. 
+               // </summary>
+               static public Expression ConvertImplicitStandard (TypeContainer tc, Expression expr,
+                                                                 Type target_type, Location l)
+               {
+                       Type expr_type = expr.Type;
+                       Expression e;
+
+                       if (expr_type == target_type)
+                               return expr;
+
+                       e = ImplicitNumericConversion (tc, expr, target_type, l);
+                       if (e != null)
+                               return e;
+
+                       e = ImplicitReferenceConversion (expr, target_type);
+                       if (e != null)
+                               return e;
+
+                       if (target_type.IsSubclassOf (TypeManager.enum_type) && expr is IntLiteral){
+                               IntLiteral i = (IntLiteral) expr;
+
+                               if (i.Value == 0)
+                                       return new EmptyCast (expr, target_type);
+                       }
+                       return null;
+               }
+               // <summary>
+               //   Attemps to perform an implict constant conversion of the IntLiteral
+               //   into a different data type using casts (See Implicit Constant
+               //   Expression Conversions)
+               // </summary>
+               static protected Expression TryImplicitIntConversion (Type target_type, IntLiteral il)
+               {
+                       int value = il.Value;
+                       
+                       if (target_type == TypeManager.sbyte_type){
+                               if (value >= SByte.MinValue && value <= SByte.MaxValue)
+                                       return il;
+                       } else if (target_type == TypeManager.byte_type){
+                               if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
+                                       return il;
+                       } else if (target_type == TypeManager.short_type){
+                               if (value >= Int16.MinValue && value <= Int16.MaxValue)
+                                       return il;
+                       } else if (target_type == TypeManager.ushort_type){
+                               if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
+                                       return il;
+                       } else if (target_type == TypeManager.uint32_type){
+                               //
+                               // we can optimize this case: a positive int32
+                               // always fits on a uint32
+                               //
+                               if (value >= 0)
+                                       return il;
+                       } else if (target_type == TypeManager.uint64_type){
+                               //
+                               // we can optimize this case: a positive int32
+                               // always fits on a uint64.  But we need an opcode
+                               // to do it.
+                               //
+                               if (value >= 0)
+                                       return new OpcodeCast (il, target_type, OpCodes.Conv_I8);
+                       }
+
+                       return null;
+               }
+
+               // <summary>
+               //   Attemptes to implicityly convert `target' into `type', using
+               //   ConvertImplicit.  If there is no implicit conversion, then
+               //   an error is signaled
+               // </summary>
+               static public Expression ConvertImplicitRequired (TypeContainer tc, Expression target,
+                                                                 Type type, Location l)
+               {
+                       Expression e;
+                       
+                       e = ConvertImplicit (tc, target, type, l);
+                       if (e != null)
+                               return e;
+                       
+                       string msg = "Can not convert implicitly from `"+
+                               TypeManager.CSharpName (target.Type) + "' to `" +
+                               TypeManager.CSharpName (type) + "'";
+
+                       Error (tc, 29, l, msg);
+
+                       return null;
+               }
+
+               // <summary>
+               //   Performs the explicit numeric conversions
+               // </summary>
+               static Expression ConvertNumericExplicit (TypeContainer tc, Expression expr,
+                                                         Type target_type)
+               {
+                       Type expr_type = expr.Type;
+                       
+                       if (expr_type == TypeManager.sbyte_type){
+                               //
+                               // From sbyte to byte, ushort, uint, ulong, char
+                               //
+                               if (target_type == TypeManager.byte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
+                               if (target_type == TypeManager.ushort_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                               if (target_type == TypeManager.uint32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
+                               if (target_type == TypeManager.uint64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                               if (target_type == TypeManager.char_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                       } else if (expr_type == TypeManager.byte_type){
+                               //
+                               // From byte to sbyte and char
+                               //
+                               if (target_type == TypeManager.sbyte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
+                               if (target_type == TypeManager.char_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                       } else if (expr_type == TypeManager.short_type){
+                               //
+                               // From short to sbyte, byte, ushort, uint, ulong, char
+                               //
+                               if (target_type == TypeManager.sbyte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
+                               if (target_type == TypeManager.byte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
+                               if (target_type == TypeManager.ushort_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                               if (target_type == TypeManager.uint32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
+                               if (target_type == TypeManager.uint64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                               if (target_type == TypeManager.char_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                       } else if (expr_type == TypeManager.ushort_type){
+                               //
+                               // From ushort to sbyte, byte, short, char
+                               //
+                               if (target_type == TypeManager.sbyte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
+                               if (target_type == TypeManager.byte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
+                               if (target_type == TypeManager.short_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
+                               if (target_type == TypeManager.char_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                       } else if (expr_type == TypeManager.int32_type){
+                               //
+                               // From int to sbyte, byte, short, ushort, uint, ulong, char
+                               //
+                               if (target_type == TypeManager.sbyte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
+                               if (target_type == TypeManager.byte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
+                               if (target_type == TypeManager.short_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
+                               if (target_type == TypeManager.ushort_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                               if (target_type == TypeManager.uint32_type)
+                                       return new EmptyCast (expr, target_type);
+                               if (target_type == TypeManager.uint64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                               if (target_type == TypeManager.char_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                       } else if (expr_type == TypeManager.uint32_type){
+                               //
+                               // From uint to sbyte, byte, short, ushort, int, char
+                               //
+                               if (target_type == TypeManager.sbyte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
+                               if (target_type == TypeManager.byte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
+                               if (target_type == TypeManager.short_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
+                               if (target_type == TypeManager.ushort_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                               if (target_type == TypeManager.int32_type)
+                                       return new EmptyCast (expr, target_type);
+                               if (target_type == TypeManager.char_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                       } else if (expr_type == TypeManager.int64_type){
+                               //
+                               // From long to sbyte, byte, short, ushort, int, uint, ulong, char
+                               //
+                               if (target_type == TypeManager.sbyte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
+                               if (target_type == TypeManager.byte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
+                               if (target_type == TypeManager.short_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
+                               if (target_type == TypeManager.ushort_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                               if (target_type == TypeManager.int32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
+                               if (target_type == TypeManager.uint32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
+                               if (target_type == TypeManager.uint64_type)
+                                       return new EmptyCast (expr, target_type);
+                               if (target_type == TypeManager.char_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                       } else if (expr_type == TypeManager.uint64_type){
+                               //
+                               // From ulong to sbyte, byte, short, ushort, int, uint, long, char
+                               //
+                               if (target_type == TypeManager.sbyte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
+                               if (target_type == TypeManager.byte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
+                               if (target_type == TypeManager.short_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
+                               if (target_type == TypeManager.ushort_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                               if (target_type == TypeManager.int32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
+                               if (target_type == TypeManager.uint32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
+                               if (target_type == TypeManager.int64_type)
+                                       return new EmptyCast (expr, target_type);
+                               if (target_type == TypeManager.char_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                       } else if (expr_type == TypeManager.char_type){
+                               //
+                               // From char to sbyte, byte, short
+                               //
+                               if (target_type == TypeManager.sbyte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
+                               if (target_type == TypeManager.byte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
+                               if (target_type == TypeManager.short_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
+                       } else if (expr_type == TypeManager.float_type){
+                               //
+                               // From float to sbyte, byte, short,
+                               // ushort, int, uint, long, ulong, char
+                               // or decimal
+                               //
+                               if (target_type == TypeManager.sbyte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
+                               if (target_type == TypeManager.byte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
+                               if (target_type == TypeManager.short_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
+                               if (target_type == TypeManager.ushort_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                               if (target_type == TypeManager.int32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
+                               if (target_type == TypeManager.uint32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
+                               if (target_type == TypeManager.int64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                               if (target_type == TypeManager.uint64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
+                               if (target_type == TypeManager.char_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                               if (target_type == TypeManager.decimal_type)
+                                       return InternalTypeConstructor (tc, expr, target_type);
+                       } else if (expr_type == TypeManager.double_type){
+                               //
+                               // From double to byte, byte, short,
+                               // ushort, int, uint, long, ulong,
+                               // char, float or decimal
+                               //
+                               if (target_type == TypeManager.sbyte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
+                               if (target_type == TypeManager.byte_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
+                               if (target_type == TypeManager.short_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
+                               if (target_type == TypeManager.ushort_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                               if (target_type == TypeManager.int32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
+                               if (target_type == TypeManager.uint32_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
+                               if (target_type == TypeManager.int64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
+                               if (target_type == TypeManager.uint64_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
+                               if (target_type == TypeManager.char_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
+                               if (target_type == TypeManager.float_type)
+                                       return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
+                               if (target_type == TypeManager.decimal_type)
+                                       return InternalTypeConstructor (tc, expr, target_type);
+                       } 
+
+                       // decimal is taken care of by the op_Explicit methods.
+
+                       return null;
+               }
+
+               // <summary>
+               //   Implements Explicit Reference conversions
+               // </summary>
+               static Expression ConvertReferenceExplicit (TypeContainer tc, Expression expr,
+                                                         Type target_type)
+               {
+                       Type expr_type = expr.Type;
+                       bool target_is_value_type = target_type.IsValueType;
+                       
+                       //
+                       // From object to any reference type
+                       //
+                       if (expr_type == TypeManager.object_type && !target_is_value_type)
+                               return new ClassCast (expr, expr_type);
+
+                       return null;
+               }
+               
+               // <summary>
+               //   Performs an explicit conversion of the expression `expr' whose
+               //   type is expr.Type to `target_type'.
+               // </summary>
+               static public Expression ConvertExplicit (TypeContainer tc, Expression expr,
+                                                         Type target_type)
+               {
+                       Expression ne = ConvertImplicit (tc, expr, target_type, Location.Null);
+
+                       if (ne != null)
+                               return ne;
+
+                       ne = ConvertNumericExplicit (tc, expr, target_type);
+                       if (ne != null)
+                               return ne;
+
+                       ne = ConvertReferenceExplicit (tc, expr, target_type);
+                       if (ne != null)
+                               return ne;
+                       
+                       return null;
+               }
+
+               static string ExprClassName (ExprClass c)
+               {
+                       switch (c){
+                       case ExprClass.Invalid:
+                               return "Invalid";
+                       case ExprClass.Value:
+                               return "value";
+                       case ExprClass.Variable:
+                               return "variable";
+                       case ExprClass.Namespace:
+                               return "namespace";
+                       case ExprClass.Type:
+                               return "type";
+                       case ExprClass.MethodGroup:
+                               return "method group";
+                       case ExprClass.PropertyAccess:
+                               return "property access";
+                       case ExprClass.EventAccess:
+                               return "event access";
+                       case ExprClass.IndexerAccess:
+                               return "indexer access";
+                       case ExprClass.Nothing:
+                               return "null";
                        }
+                       throw new Exception ("Should not happen");
+               }
+               
+               // <summary>
+               //   Reports that we were expecting `expr' to be of class `expected'
+               // </summary>
+               protected void report118 (TypeContainer tc, Location l, Expression expr, string expected)
+               {
+                       string kind = "Unknown";
+                       
+                       if (expr != null)
+                               kind = ExprClassName (expr.ExprClass);
+
+                       Error (tc, 118, l, "Expression denotes a '" + kind +
+                              "' where an " + expected + " was expected");
+               }
+       }
+
+       // <summary>
+       //   This is just a base class for expressions that can
+       //   appear on statements (invocations, object creation,
+       //   assignments, post/pre increment and decrement).  The idea
+       //   being that they would support an extra Emition interface that
+       //   does not leave a result on the stack.
+       // </summary>
+
+       public abstract class ExpressionStatement : Expression {
+
+               // <summary>
+               //   Requests the expression to be emitted in a `statement'
+               //   context.  This means that no new value is left on the
+               //   stack after invoking this method (constrasted with
+               //   Emit that will always leave a value on the stack).
+               // </summary>
+               public abstract void EmitStatement (EmitContext ec);
+       }
+
+       // <summary>
+       //   This kind of cast is used to encapsulate the child
+       //   whose type is child.Type into an expression that is
+       //   reported to return "return_type".  This is used to encapsulate
+       //   expressions which have compatible types, but need to be dealt
+       //   at higher levels with.
+       //
+       //   For example, a "byte" expression could be encapsulated in one
+       //   of these as an "unsigned int".  The type for the expression
+       //   would be "unsigned int".
+       //
+       // </summary>
+       
+       public class EmptyCast : Expression {
+               protected Expression child;
+
+               public EmptyCast (Expression child, Type return_type)
+               {
+                       ExprClass = child.ExprClass;
+                       type = return_type;
+                       this.child = child;
+               }
+
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       // This should never be invoked, we are born in fully
+                       // initialized state.
+
+                       return this;
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       child.Emit (ec);
+               }                       
+       }
+
+       // <summary>
+       //   This kind of cast is used to encapsulate Value Types in objects.
+       //
+       //   The effect of it is to box the value type emitted by the previous
+       //   operation.
+       // </summary>
+       public class BoxedCast : EmptyCast {
+
+               public BoxedCast (Expression expr)
+                       : base (expr, TypeManager.object_type)
+               {
+               }
+
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       // This should never be invoked, we are born in fully
+                       // initialized state.
+
+                       return this;
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       base.Emit (ec);
+                       ec.ig.Emit (OpCodes.Box, child.Type);
                }
        }
 
-       public class Probe : Expression {
-               string type;
-               Expression expr;
-               Operator oper;
+       // <summary>
+       //   This kind of cast is used to encapsulate a child expression
+       //   that can be trivially converted to a target type using one or 
+       //   two opcodes.  The opcodes are passed as arguments.
+       // </summary>
+       public class OpcodeCast : EmptyCast {
+               OpCode op, op2;
+               bool second_valid;
+               
+               public OpcodeCast (Expression child, Type return_type, OpCode op)
+                       : base (child, return_type)
+                       
+               {
+                       this.op = op;
+                       second_valid = false;
+               }
+
+               public OpcodeCast (Expression child, Type return_type, OpCode op, OpCode op2)
+                       : base (child, return_type)
+                       
+               {
+                       this.op = op;
+                       this.op2 = op2;
+                       second_valid = true;
+               }
+
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       // This should never be invoked, we are born in fully
+                       // initialized state.
+
+                       return this;
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       base.Emit (ec);
+                       ec.ig.Emit (op);
+
+                       if (second_valid)
+                               ec.ig.Emit (op2);
+               }                       
+               
+       }
+
+       // <summary>
+       //   This kind of cast is used to encapsulate a child and cast it
+       //   to the class requested
+       // </summary>
+       public class ClassCast : EmptyCast {
+               public ClassCast (Expression child, Type return_type)
+                       : base (child, return_type)
+                       
+               {
+               }
+
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       // This should never be invoked, we are born in fully
+                       // initialized state.
+
+                       return this;
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       base.Emit (ec);
+
+                       ec.ig.Emit (OpCodes.Castclass, type);
+               }                       
+               
+       }
+       
+       // <summary>
+       //   Unary expressions.  
+       // </summary>
+       //
+       // <remarks>
+       //   Unary implements unary expressions.   It derives from
+       //   ExpressionStatement becuase the pre/post increment/decrement
+       //   operators can be used in a statement context.
+       // </remarks>
+       public class Unary : ExpressionStatement {
+               public enum Operator {
+                       Addition, Subtraction, Negate, BitComplement,
+                       Indirection, AddressOf, PreIncrement,
+                       PreDecrement, PostIncrement, PostDecrement
+               }
+
+               Operator   oper;
+               Expression expr;
+               ArrayList  Arguments;
+               MethodBase method;
+               Location   location;
+               
+               public Unary (Operator op, Expression expr, Location loc)
+               {
+                       this.oper = op;
+                       this.expr = expr;
+                       this.location = loc;
+               }
+
+               public Expression Expr {
+                       get {
+                               return expr;
+                       }
+
+                       set {
+                               expr = value;
+                       }
+               }
+
+               public Operator Oper {
+                       get {
+                               return oper;
+                       }
+
+                       set {
+                               oper = value;
+                       }
+               }
+
+               // <summary>
+               //   Returns a stringified representation of the Operator
+               // </summary>
+               string OperName ()
+               {
+                       switch (oper){
+                       case Operator.Addition:
+                               return "+";
+                       case Operator.Subtraction:
+                               return "-";
+                       case Operator.Negate:
+                               return "!";
+                       case Operator.BitComplement:
+                               return "~";
+                       case Operator.AddressOf:
+                               return "&";
+                       case Operator.Indirection:
+                               return "*";
+                       case Operator.PreIncrement : case Operator.PostIncrement :
+                               return "++";
+                       case Operator.PreDecrement : case Operator.PostDecrement :
+                               return "--";
+                       }
+
+                       return oper.ToString ();
+               }
+
+               Expression ForceConversion (TypeContainer tc, Expression expr, Type target_type)
+               {
+                       if (expr.Type == target_type)
+                               return expr;
+
+                       return ConvertImplicit (tc, expr, target_type, new Location (-1));
+               }
+
+               void report23 (Report r, Type t)
+               {
+                       r.Error (23, "Operator " + OperName () + " cannot be applied to operand of type `" +
+                                TypeManager.CSharpName (t) + "'");
+               }
+
+               // <summary>
+               //   Returns whether an object of type `t' can be incremented
+               //   or decremented with add/sub (ie, basically whether we can
+               //   use pre-post incr-decr operations on it, but it is not a
+               //   System.Decimal, which we test elsewhere)
+               // </summary>
+               static bool IsIncrementableNumber (Type t)
+               {
+                       return (t == TypeManager.sbyte_type) ||
+                               (t == TypeManager.byte_type) ||
+                               (t == TypeManager.short_type) ||
+                               (t == TypeManager.ushort_type) ||
+                               (t == TypeManager.int32_type) ||
+                               (t == TypeManager.uint32_type) ||
+                               (t == TypeManager.int64_type) ||
+                               (t == TypeManager.uint64_type) ||
+                               (t == TypeManager.char_type) ||
+                               (t.IsSubclassOf (TypeManager.enum_type)) ||
+                               (t == TypeManager.float_type) ||
+                               (t == TypeManager.double_type);
+               }
+                       
+               Expression ResolveOperator (TypeContainer tc)
+               {
+                       Type expr_type = expr.Type;
+
+                       //
+                       // Step 1: Perform Operator Overload location
+                       //
+                       Expression mg;
+                       string op_name;
+                               
+                       if (oper == Operator.PostIncrement || oper == Operator.PreIncrement)
+                               op_name = "op_Increment";
+                       else if (oper == Operator.PostDecrement || oper == Operator.PreDecrement)
+                               op_name = "op_Decrement";
+                       else
+                               op_name = "op_" + oper;
+
+                       mg = MemberLookup (tc, expr_type, op_name, false);
+
+                       if (mg == null && expr_type != TypeManager.object_type)
+                               mg = MemberLookup (tc, expr_type.BaseType, op_name, false);
+                       
+                       if (mg != null) {
+                               Arguments = new ArrayList ();
+                               Arguments.Add (new Argument (expr, Argument.AType.Expression));
+                               
+                               method = Invocation.OverloadResolve (tc, (MethodGroupExpr) mg,
+                                                                    Arguments, location);
+                               if (method != null) {
+                                       MethodInfo mi = (MethodInfo) method;
+
+                                       type = mi.ReturnType;
+                                       return this;
+                               }
+                       }
+
+                       //
+                       // Step 2: Default operations on CLI native types.
+                       //
+
+                       // Only perform numeric promotions on:
+                       // +, -, ++, --
+
+                       if (expr_type == null)
+                               return null;
+                       
+                       if (oper == Operator.Negate){
+                               if (expr_type != TypeManager.bool_type) {
+                                       report23 (tc.RootContext.Report, expr.Type);
+                                       return null;
+                               }
+                               
+                               type = TypeManager.bool_type;
+                               return this;
+                       }
+
+                       if (oper == Operator.BitComplement) {
+                               if (!((expr_type == TypeManager.int32_type) ||
+                                     (expr_type == TypeManager.uint32_type) ||
+                                     (expr_type == TypeManager.int64_type) ||
+                                     (expr_type == TypeManager.uint64_type) ||
+                                     (expr_type.IsSubclassOf (TypeManager.enum_type)))){
+                                       report23 (tc.RootContext.Report, expr.Type);
+                                       return null;
+                               }
+                               type = expr_type;
+                               return this;
+                       }
+
+                       if (oper == Operator.Addition) {
+                               //
+                               // A plus in front of something is just a no-op, so return the child.
+                               //
+                               return expr;
+                       }
+
+                       //
+                       // Deals with -literals
+                       // int     operator- (int x)
+                       // long    operator- (long x)
+                       // float   operator- (float f)
+                       // double  operator- (double d)
+                       // decimal operator- (decimal d)
+                       //
+                       if (oper == Operator.Subtraction){
+                               //
+                               // Fold a "- Constant" into a negative constant
+                               //
+                       
+                               Expression e = null;
+
+                               //
+                               // Is this a constant? 
+                               //
+                               if (expr is IntLiteral)
+                                       e = new IntLiteral (-((IntLiteral) expr).Value);
+                               else if (expr is LongLiteral)
+                                       e = new LongLiteral (-((LongLiteral) expr).Value);
+                               else if (expr is FloatLiteral)
+                                       e = new FloatLiteral (-((FloatLiteral) expr).Value);
+                               else if (expr is DoubleLiteral)
+                                       e = new DoubleLiteral (-((DoubleLiteral) expr).Value);
+                               else if (expr is DecimalLiteral)
+                                       e = new DecimalLiteral (-((DecimalLiteral) expr).Value);
+                               
+                               if (e != null){
+                                       e = e.Resolve (tc);
+                                       return e;
+                               }
+
+                               //
+                               // Not a constant we can optimize, perform numeric 
+                               // promotions to int, long, double.
+                               //
+                               //
+                               // The following is inneficient, because we call
+                               // ConvertImplicit too many times.
+                               //
+                               // It is also not clear if we should convert to Float
+                               // or Double initially.
+                               //
+                               Location l = new Location (-1);
+                               
+                               if (expr_type == TypeManager.uint32_type){
+                                       //
+                                       // FIXME: handle exception to this rule that
+                                       // permits the int value -2147483648 (-2^31) to
+                                       // bt written as a decimal interger literal
+                                       //
+                                       type = TypeManager.int64_type;
+                                       expr = ConvertImplicit (tc, expr, type, l);
+                                       return this;
+                               }
+
+                               if (expr_type == TypeManager.uint64_type){
+                                       //
+                                       // FIXME: Handle exception of `long value'
+                                       // -92233720368547758087 (-2^63) to be written as
+                                       // decimal integer literal.
+                                       //
+                                       report23 (tc.RootContext.Report, expr_type);
+                                       return null;
+                               }
+
+                               e = ConvertImplicit (tc, expr, TypeManager.int32_type, l);
+                               if (e != null){
+                                       expr = e;
+                                       type = e.Type;
+                                       return this;
+                               } 
+
+                               e = ConvertImplicit (tc, expr, TypeManager.int64_type, l);
+                               if (e != null){
+                                       expr = e;
+                                       type = e.Type;
+                                       return this;
+                               }
+
+                               e = ConvertImplicit (tc, expr, TypeManager.double_type, l);
+                               if (e != null){
+                                       expr = e;
+                                       type = e.Type;
+                                       return this;
+                               }
+
+                               report23 (tc.RootContext.Report, expr_type);
+                               return null;
+                       }
+
+                       //
+                       // The operand of the prefix/postfix increment decrement operators
+                       // should be an expression that is classified as a variable,
+                       // a property access or an indexer access
+                       //
+                       if (oper == Operator.PreDecrement || oper == Operator.PreIncrement ||
+                           oper == Operator.PostDecrement || oper == Operator.PostIncrement){
+                               if (expr.ExprClass == ExprClass.Variable){
+                                       if (IsIncrementableNumber (expr_type) ||
+                                           expr_type == TypeManager.decimal_type){
+                                               type = expr_type;
+                                               return this;
+                                       }
+                               } else if (expr.ExprClass == ExprClass.IndexerAccess){
+                                       //
+                                       // FIXME: Verify that we have both get and set methods
+                                       //
+                                       throw new Exception ("Implement me");
+                               } else if (expr.ExprClass == ExprClass.PropertyAccess){
+                                       //
+                                       // FIXME: Verify that we have both get and set methods
+                                       //
+                                       throw new Exception ("Implement me");
+                               } else {
+                                       report118 (tc, location, expr,
+                                                  "variable, indexer or property access");
+                               }
+                       }
+
+                       if (oper == Operator.AddressOf){
+                               if (expr.ExprClass != ExprClass.Variable){
+                                       Error (tc, 211, "Cannot take the address of non-variables");
+                                       return null;
+                               }
+                               type = Type.GetType (expr.Type.ToString () + "*");
+                       }
+                       
+                       Error (tc, 187, "No such operator '" + OperName () + "' defined for type '" +
+                              TypeManager.CSharpName (expr_type) + "'");
+                       return null;
+
+               }
+
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       expr = expr.Resolve (tc);
+
+                       if (expr == null)
+                               return null;
+
+                       eclass = ExprClass.Value;
+                       return ResolveOperator (tc);
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       ILGenerator ig = ec.ig;
+                       Type expr_type = expr.Type;
+
+                       if (method != null) {
+
+                               // Note that operators are static anyway
+                               
+                               if (Arguments != null) 
+                                       Invocation.EmitArguments (ec, method, Arguments);
+
+                               //
+                               // Post increment/decrement operations need a copy at this
+                               // point.
+                               //
+                               if (oper == Operator.PostDecrement || oper == Operator.PostIncrement)
+                                       ig.Emit (OpCodes.Dup);
+                               
+
+                               ig.Emit (OpCodes.Call, (MethodInfo) method);
+
+                               //
+                               // Pre Increment and Decrement operators
+                               //
+                               if (oper == Operator.PreIncrement || oper == Operator.PreDecrement){
+                                       ig.Emit (OpCodes.Dup);
+                               }
+                               
+                               //
+                               // Increment and Decrement should store the result
+                               //
+                               if (oper == Operator.PreDecrement || oper == Operator.PreIncrement ||
+                                   oper == Operator.PostDecrement || oper == Operator.PostIncrement){
+                                       ((LValue) expr).Store (ec);
+                               }
+                               return;
+                       }
+                       
+                       switch (oper) {
+                       case Operator.Addition:
+                               throw new Exception ("This should be caught by Resolve");
+                               
+                       case Operator.Subtraction:
+                               expr.Emit (ec);
+                               ig.Emit (OpCodes.Neg);
+                               break;
+                               
+                       case Operator.Negate:
+                               expr.Emit (ec);
+                               ig.Emit (OpCodes.Ldc_I4_0);
+                               ig.Emit (OpCodes.Ceq);
+                               break;
+                               
+                       case Operator.BitComplement:
+                               expr.Emit (ec);
+                               ig.Emit (OpCodes.Not);
+                               break;
+                               
+                       case Operator.AddressOf:
+                               ((LValue)expr).AddressOf (ec);
+                               break;
+                               
+                       case Operator.Indirection:
+                               throw new Exception ("Not implemented yet");
+                               
+                       case Operator.PreIncrement:
+                       case Operator.PreDecrement:
+                               if (expr.ExprClass == ExprClass.Variable){
+                                       //
+                                       // Resolve already verified that it is an "incrementable"
+                                       // 
+                                       expr.Emit (ec);
+                                       ig.Emit (OpCodes.Ldc_I4_1);
+                                       
+                                       if (oper == Operator.PreDecrement)
+                                               ig.Emit (OpCodes.Sub);
+                                       else
+                                               ig.Emit (OpCodes.Add);
+                                       ig.Emit (OpCodes.Dup);
+                                       ((LValue) expr).Store (ec);
+                               } else {
+                                       throw new Exception ("Handle Indexers and Properties here");
+                               }
+                               break;
+                               
+                       case Operator.PostIncrement:
+                       case Operator.PostDecrement:
+                               if (expr.ExprClass == ExprClass.Variable){
+                                       //
+                                       // Resolve already verified that it is an "incrementable"
+                                       // 
+                                       expr.Emit (ec);
+                                       ig.Emit (OpCodes.Dup);
+                                       ig.Emit (OpCodes.Ldc_I4_1);
+                                       
+                                       if (oper == Operator.PostDecrement)
+                                               ig.Emit (OpCodes.Sub);
+                                       else
+                                               ig.Emit (OpCodes.Add);
+                                       ((LValue) expr).Store (ec);
+                               } else {
+                                       throw new Exception ("Handle Indexers and Properties here");
+                               }
+                               break;
+                               
+                       default:
+                               throw new Exception ("This should not happen: Operator = "
+                                                    + oper.ToString ());
+                       }
+               }
+               
+
+               public override void EmitStatement (EmitContext ec)
+               {
+                       //
+                       // FIXME: we should rewrite this code to generate
+                       // better code for ++ and -- as we know we wont need
+                       // the values on the stack
+                       //
+                       Emit (ec);
+                       ec.ig.Emit (OpCodes.Pop);
+               }
+       }
+       
+       public class Probe : Expression {
+               public readonly string ProbeType;
+               public readonly Operator Oper;
+               Expression expr;
+               Type probe_type;
+               
+               public enum Operator {
+                       Is, As
+               }
+               
+               public Probe (Operator oper, Expression expr, string probe_type)
+               {
+                       Oper = oper;
+                       ProbeType = probe_type;
+                       this.expr = expr;
+               }
+
+               public Expression Expr {
+                       get {
+                               return expr;
+                       }
+               }
+               
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       probe_type = tc.LookupType (ProbeType, false);
+
+                       if (probe_type == null)
+                               return null;
+
+                       expr = expr.Resolve (tc);
+                       
+                       type = TypeManager.bool_type;
+                       eclass = ExprClass.Value;
+
+                       return this;
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       ILGenerator ig = ec.ig;
+                       
+                       expr.Emit (ec);
+                       
+                       if (Oper == Operator.Is){
+                               ig.Emit (OpCodes.Isinst, probe_type);
+                               ig.Emit (OpCodes.Ldnull);
+                               ig.Emit (OpCodes.Cgt_Un);
+                       } else {
+                               ig.Emit (OpCodes.Isinst, probe_type);
+                       }
+               }
+       }
+
+       // <summary>
+       //   This represents a typecast in the source language.
+       //
+       //   FIXME: Cast expressions have an unusual set of parsing
+       //   rules, we need to figure those out.
+       // </summary>
+       public class Cast : Expression {
+               string target_type;
+               Expression expr;
+                       
+               public Cast (string cast_type, Expression expr)
+               {
+                       this.target_type = cast_type;
+                       this.expr = expr;
+               }
+
+               public string TargetType {
+                       get {
+                               return target_type;
+                       }
+               }
+
+               public Expression Expr {
+                       get {
+                               return expr;
+                       }
+                       set {
+                               expr = value;
+                       }
+               }
+               
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       expr = expr.Resolve (tc);
+                       if (expr == null)
+                               return null;
+                       
+                       type = tc.LookupType (target_type, false);
+                       eclass = ExprClass.Value;
+                       
+                       if (type == null)
+                               return null;
+
+                       expr = ConvertExplicit (tc, expr, type);
+
+                       return expr;
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       //
+                       // This one will never happen
+                       //
+                       throw new Exception ("Should not happen");
+               }
+       }
+
+       public class Binary : Expression {
+               public enum Operator {
+                       Multiply, Division, Modulus,
+                       Addition, Subtraction,
+                       LeftShift, RightShift,
+                       LessThan, GreaterThan, LessThanOrEqual, GreaterThanOrEqual, 
+                       Equality, Inequality,
+                       BitwiseAnd,
+                       ExclusiveOr,
+                       BitwiseOr,
+                       LogicalAnd,
+                       LogicalOr
+               }
+
+               Operator oper;
+               Expression left, right;
+               MethodBase method;
+               ArrayList  Arguments;
+               Location   location;
+               
+
+               public Binary (Operator oper, Expression left, Expression right, Location loc)
+               {
+                       this.oper = oper;
+                       this.left = left;
+                       this.right = right;
+                       this.location = loc;
+               }
+
+               public Operator Oper {
+                       get {
+                               return oper;
+                       }
+                       set {
+                               oper = value;
+                       }
+               }
+               
+               public Expression Left {
+                       get {
+                               return left;
+                       }
+                       set {
+                               left = value;
+                       }
+               }
+
+               public Expression Right {
+                       get {
+                               return right;
+                       }
+                       set {
+                               right = value;
+                       }
+               }
+
+
+               // <summary>
+               //   Returns a stringified representation of the Operator
+               // </summary>
+               string OperName ()
+               {
+                       switch (oper){
+                       case Operator.Multiply:
+                               return "*";
+                       case Operator.Division:
+                               return "/";
+                       case Operator.Modulus:
+                               return "%";
+                       case Operator.Addition:
+                               return "+";
+                       case Operator.Subtraction:
+                               return "-";
+                       case Operator.LeftShift:
+                               return "<<";
+                       case Operator.RightShift:
+                               return ">>";
+                       case Operator.LessThan:
+                               return "<";
+                       case Operator.GreaterThan:
+                               return ">";
+                       case Operator.LessThanOrEqual:
+                               return "<=";
+                       case Operator.GreaterThanOrEqual:
+                               return ">=";
+                       case Operator.Equality:
+                               return "==";
+                       case Operator.Inequality:
+                               return "!=";
+                       case Operator.BitwiseAnd:
+                               return "&";
+                       case Operator.BitwiseOr:
+                               return "|";
+                       case Operator.ExclusiveOr:
+                               return "^";
+                       case Operator.LogicalOr:
+                               return "||";
+                       case Operator.LogicalAnd:
+                               return "&&";
+                       }
+
+                       return oper.ToString ();
+               }
+
+               Expression ForceConversion (TypeContainer tc, Expression expr, Type target_type)
+               {
+                       if (expr.Type == target_type)
+                               return expr;
+
+                       return ConvertImplicit (tc, expr, target_type, new Location (-1));
+               }
+               
+               //
+               // Note that handling the case l == Decimal || r == Decimal
+               // is taken care of by the Step 1 Operator Overload resolution.
+               //
+               void DoNumericPromotions (TypeContainer tc, Type l, Type r)
+               {
+                       if (l == TypeManager.double_type || r == TypeManager.double_type){
+                               //
+                               // If either operand is of type double, the other operand is
+                               // conveted to type double.
+                               //
+                               if (r != TypeManager.double_type)
+                                       right = ConvertImplicit (tc, right, TypeManager.double_type, location);
+                               if (l != TypeManager.double_type)
+                                       left = ConvertImplicit (tc, left, TypeManager.double_type, location);
+                               
+                               type = TypeManager.double_type;
+                       } else if (l == TypeManager.float_type || r == TypeManager.float_type){
+                               //
+                               // if either operand is of type float, th eother operand is
+                               // converd to type float.
+                               //
+                               if (r != TypeManager.double_type)
+                                       right = ConvertImplicit (tc, right, TypeManager.float_type, location);
+                               if (l != TypeManager.double_type)
+                                       left = ConvertImplicit (tc, left, TypeManager.float_type, location);
+                               type = TypeManager.float_type;
+                       } else if (l == TypeManager.uint64_type || r == TypeManager.uint64_type){
+                               Expression e;
+                               Type other;
+                               //
+                               // If either operand is of type ulong, the other operand is
+                               // converted to type ulong.  or an error ocurrs if the other
+                               // operand is of type sbyte, short, int or long
+                               //
+                               
+                               if (l == TypeManager.uint64_type){
+                                       if (r != TypeManager.uint64_type && right is IntLiteral){
+                                               e = TryImplicitIntConversion (l, (IntLiteral) right);
+                                               if (e != null)
+                                                       right = e;
+                                       }
+                                       other = right.Type;
+                               } else {
+                                       if (left is IntLiteral){
+                                               e = TryImplicitIntConversion (r, (IntLiteral) left);
+                                               if (e != null)
+                                                       left = e;
+                                       }
+                                       other = left.Type;
+                               }
+
+                               if ((other == TypeManager.sbyte_type) ||
+                                   (other == TypeManager.short_type) ||
+                                   (other == TypeManager.int32_type) ||
+                                   (other == TypeManager.int64_type)){
+                                       string oper = OperName ();
+                                       
+                                       Error (tc, 34, location, "Operator `" + OperName ()
+                                              + "' is ambiguous on operands of type `"
+                                              + TypeManager.CSharpName (l) + "' "
+                                              + "and `" + TypeManager.CSharpName (r)
+                                              + "'");
+                               }
+                               type = TypeManager.uint64_type;
+                       } else if (l == TypeManager.int64_type || r == TypeManager.int64_type){
+                               //
+                               // If either operand is of type long, the other operand is converted
+                               // to type long.
+                               //
+                               if (l != TypeManager.int64_type)
+                                       left = ConvertImplicit (tc, left, TypeManager.int64_type, location);
+                               if (r != TypeManager.int64_type)
+                                       right = ConvertImplicit (tc, right, TypeManager.int64_type, location);
+
+                               type = TypeManager.int64_type;
+                       } else if (l == TypeManager.uint32_type || r == TypeManager.uint32_type){
+                               //
+                               // If either operand is of type uint, and the other
+                               // operand is of type sbyte, short or int, othe operands are
+                               // converted to type long.
+                               //
+                               Type other = null;
+                               
+                               if (l == TypeManager.uint32_type)
+                                       other = r;
+                               else if (r == TypeManager.uint32_type)
+                                       other = l;
+
+                               if ((other == TypeManager.sbyte_type) ||
+                                   (other == TypeManager.short_type) ||
+                                   (other == TypeManager.int32_type)){
+                                       left = ForceConversion (tc, left, TypeManager.int64_type);
+                                       right = ForceConversion (tc, right, TypeManager.int64_type);
+                                       type = TypeManager.int64_type;
+                               } else {
+                                       //
+                                       // if either operand is of type uint, the other
+                                       // operand is converd to type uint
+                                       //
+                                       left = ForceConversion (tc, left, TypeManager.uint32_type);
+                                       right = ForceConversion (tc, right, TypeManager.uint32_type);
+                                       type = TypeManager.uint32_type;
+                               } 
+                       } else if (l == TypeManager.decimal_type || r == TypeManager.decimal_type){
+                               if (l != TypeManager.decimal_type)
+                                       left = ConvertImplicit (tc, left, TypeManager.decimal_type, location);
+                               if (r != TypeManager.decimal_type)
+                                       right = ConvertImplicit (tc, right, TypeManager.decimal_type, location);
+
+                               type = TypeManager.decimal_type;
+                       } else {
+                               left = ForceConversion (tc, left, TypeManager.int32_type);
+                               right = ForceConversion (tc, right, TypeManager.int32_type);
+                               type = TypeManager.int32_type;
+                       }
+               }
+
+               void error19 (TypeContainer tc)
+               {
+                       Error (tc, 19,
+                              "Operator " + OperName () + " cannot be applied to operands of type `" +
+                              TypeManager.CSharpName (left.Type) + "' and `" +
+                              TypeManager.CSharpName (right.Type) + "'");
+                                                    
+               }
+               
+               Expression CheckShiftArguments (TypeContainer tc)
+               {
+                       Expression e;
+                       Type l = left.Type;
+                       Type r = right.Type;
+
+                       e = ForceConversion (tc, right, TypeManager.int32_type);
+                       if (e == null){
+                               error19 (tc);
+                               return null;
+                       }
+                       right = e;
+
+                       Location loc = location;
+                       
+                       if (((e = ConvertImplicit (tc, left, TypeManager.int32_type, loc)) != null) ||
+                           ((e = ConvertImplicit (tc, left, TypeManager.uint32_type, loc)) != null) ||
+                           ((e = ConvertImplicit (tc, left, TypeManager.int64_type, loc)) != null) ||
+                           ((e = ConvertImplicit (tc, left, TypeManager.uint64_type, loc)) != null)){
+                               left = e;
+                               type = e.Type;
+
+                               return this;
+                       }
+                       error19 (tc);
+                       return null;
+               }
+               
+               Expression ResolveOperator (TypeContainer tc)
+               {
+                       Type l = left.Type;
+                       Type r = right.Type;
+
+                       //
+                       // Step 1: Perform Operator Overload location
+                       //
+                       Expression left_expr, right_expr;
+                       
+                       string op = "op_" + oper;
+
+                       left_expr = MemberLookup (tc, l, op, false);
+
+                       if (left_expr == null && l != TypeManager.object_type)
+                               left_expr = MemberLookup (tc, l.BaseType, op, false);
+                       
+                       right_expr = MemberLookup (tc, r, op, false);
+                       if (right_expr != null && r != TypeManager.object_type)
+                               right_expr = MemberLookup (tc, r.BaseType, op, false);
+                       
+
+                       MethodGroupExpr union = Invocation.MakeUnionSet (left_expr, right_expr);
+
+                       if (union != null) {
+                               Arguments = new ArrayList ();
+                               Arguments.Add (new Argument (left, Argument.AType.Expression));
+                               Arguments.Add (new Argument (right, Argument.AType.Expression));
+                       
+                               method = Invocation.OverloadResolve (tc, union, Arguments, location);
+                               if (method != null) {
+                                       MethodInfo mi = (MethodInfo) method;
+                                       
+                                       type = mi.ReturnType;
+                                       return this;
+                               }
+                       }       
+                       
+                       //
+                       // Step 2: Default operations on CLI native types.
+                       //
+                       
+                       // Only perform numeric promotions on:
+                       // +, -, *, /, %, &, |, ^, ==, !=, <, >, <=, >=
+                       //
+                       if (oper == Operator.Addition){
+                               //
+                               // If any of the arguments is a string, cast to string
+                               //
+                               if (l == TypeManager.string_type){
+                                       if (r == TypeManager.string_type){
+                                               // string + string
+                                               method = TypeManager.string_concat_string_string;
+                                       } else {
+                                               // string + object
+                                               method = TypeManager.string_concat_object_object;
+                                               right = ConvertImplicit (tc, right,
+                                                                        TypeManager.object_type, location);
+                                       }
+                                       type = TypeManager.string_type;
+
+                                       Arguments = new ArrayList ();
+                                       Arguments.Add (new Argument (left, Argument.AType.Expression));
+                                       Arguments.Add (new Argument (right, Argument.AType.Expression));
+
+                                       return this;
+                                       
+                               } else if (r == TypeManager.string_type){
+                                       // object + string
+                                       method = TypeManager.string_concat_object_object;
+                                       Arguments = new ArrayList ();
+                                       Arguments.Add (new Argument (left, Argument.AType.Expression));
+                                       Arguments.Add (new Argument (right, Argument.AType.Expression));
+
+                                       left = ConvertImplicit (tc, left, TypeManager.object_type, location);
+                                       type = TypeManager.string_type;
+
+                                       return this;
+                               }
+
+                               //
+                               // FIXME: is Delegate operator + (D x, D y) handled?
+                               //
+                       }
+                       
+                       if (oper == Operator.LeftShift || oper == Operator.RightShift)
+                               return CheckShiftArguments (tc);
+
+                       if (oper == Operator.LogicalOr || oper == Operator.LogicalAnd){
+                               if (l != TypeManager.bool_type || r != TypeManager.bool_type)
+                                       error19 (tc);
+
+                               type = TypeManager.bool_type;
+                               return this;
+                       } 
+
+                       //
+                       // We are dealing with numbers
+                       //
+
+                       DoNumericPromotions (tc, l, r);
+
+                       if (left == null || right == null)
+                               return null;
+
+                       if (oper == Operator.BitwiseAnd ||
+                           oper == Operator.BitwiseOr ||
+                           oper == Operator.ExclusiveOr){
+                               if (!((l == TypeManager.int32_type) ||
+                                     (l == TypeManager.uint32_type) ||
+                                     (l == TypeManager.int64_type) ||
+                                     (l == TypeManager.uint64_type))){
+                                       error19 (tc);
+                                       return null;
+                               }
+                               type = l;
+                       }
+
+                       if (oper == Operator.Equality ||
+                           oper == Operator.Inequality ||
+                           oper == Operator.LessThanOrEqual ||
+                           oper == Operator.LessThan ||
+                           oper == Operator.GreaterThanOrEqual ||
+                           oper == Operator.GreaterThan){
+                               type = TypeManager.bool_type;
+                       }
+                       
+                       return this;
+               }
+               
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       left = left.Resolve (tc);
+                       right = right.Resolve (tc);
+
+                       if (left == null || right == null)
+                               return null;
+
+                       if (left.Type == null)
+                               throw new Exception (
+                                       "Resolve returned non null, but did not set the type! (" +
+                                       left + ")");
+                       if (right.Type == null)
+                               throw new Exception (
+                                       "Resolve returned non null, but did not set the type! (" +
+                                       right + ")");
+
+                       eclass = ExprClass.Value;
+
+                       return ResolveOperator (tc);
+               }
+
+               public bool IsBranchable ()
+               {
+                       if (oper == Operator.Equality ||
+                           oper == Operator.Inequality ||
+                           oper == Operator.LessThan ||
+                           oper == Operator.GreaterThan ||
+                           oper == Operator.LessThanOrEqual ||
+                           oper == Operator.GreaterThanOrEqual){
+                               return true;
+                       } else
+                               return false;
+               }
+
+               // <summary>
+               //   This entry point is used by routines that might want
+               //   to emit a brfalse/brtrue after an expression, and instead
+               //   they could use a more compact notation.
+               //
+               //   Typically the code would generate l.emit/r.emit, followed
+               //   by the comparission and then a brtrue/brfalse.  The comparissions
+               //   are sometimes inneficient (there are not as complete as the branches
+               //   look for the hacks in Emit using double ceqs).
+               //
+               //   So for those cases we provide EmitBranchable that can emit the
+               //   branch with the test
+               // </summary>
+               public void EmitBranchable (EmitContext ec, int target)
+               {
+                       OpCode opcode;
+                       bool close_target = false;
+                       
+                       left.Emit (ec);
+                       right.Emit (ec);
+                       
+                       switch (oper){
+                       case Operator.Equality:
+                               if (close_target)
+                                       opcode = OpCodes.Beq_S;
+                               else
+                                       opcode = OpCodes.Beq;
+                               break;
+
+                       case Operator.Inequality:
+                               if (close_target)
+                                       opcode = OpCodes.Bne_Un_S;
+                               else
+                                       opcode = OpCodes.Bne_Un;
+                               break;
+
+                       case Operator.LessThan:
+                               if (close_target)
+                                       opcode = OpCodes.Blt_S;
+                               else
+                                       opcode = OpCodes.Blt;
+                               break;
+
+                       case Operator.GreaterThan:
+                               if (close_target)
+                                       opcode = OpCodes.Bgt_S;
+                               else
+                                       opcode = OpCodes.Bgt;
+                               break;
+
+                       case Operator.LessThanOrEqual:
+                               if (close_target)
+                                       opcode = OpCodes.Ble_S;
+                               else
+                                       opcode = OpCodes.Ble;
+                               break;
+
+                       case Operator.GreaterThanOrEqual:
+                               if (close_target)
+                                       opcode = OpCodes.Bge_S;
+                               else
+                                       opcode = OpCodes.Ble;
+                               break;
+
+                       default:
+                               throw new Exception ("EmitBranchable called on non-EmitBranchable operator: "
+                                                    + oper.ToString ());
+                       }
+
+                       ec.ig.Emit (opcode, target);
+               }
+               
+               public override void Emit (EmitContext ec)
+               {
+                       ILGenerator ig = ec.ig;
+                       Type l = left.Type;
+                       Type r = right.Type;
+                       OpCode opcode;
+
+                       if (method != null) {
+
+                               // Note that operators are static anyway
+                               
+                               if (Arguments != null) 
+                                       Invocation.EmitArguments (ec, method, Arguments);
+                               
+                               if (method is MethodInfo)
+                                       ig.Emit (OpCodes.Call, (MethodInfo) method);
+                               else
+                                       ig.Emit (OpCodes.Call, (ConstructorInfo) method);
+
+                               return;
+                       }
+                       
+                       left.Emit (ec);
+                       right.Emit (ec);
+
+                       switch (oper){
+                       case Operator.Multiply:
+                               if (ec.CheckState){
+                                       if (l == TypeManager.int32_type || l == TypeManager.int64_type)
+                                               opcode = OpCodes.Mul_Ovf;
+                                       else if (l==TypeManager.uint32_type || l==TypeManager.uint64_type)
+                                               opcode = OpCodes.Mul_Ovf_Un;
+                                       else
+                                               opcode = OpCodes.Mul;
+                               } else
+                                       opcode = OpCodes.Mul;
+
+                               break;
+
+                       case Operator.Division:
+                               if (l == TypeManager.uint32_type || l == TypeManager.uint64_type)
+                                       opcode = OpCodes.Div_Un;
+                               else
+                                       opcode = OpCodes.Div;
+                               break;
+
+                       case Operator.Modulus:
+                               if (l == TypeManager.uint32_type || l == TypeManager.uint64_type)
+                                       opcode = OpCodes.Rem_Un;
+                               else
+                                       opcode = OpCodes.Rem;
+                               break;
+
+                       case Operator.Addition:
+                               if (ec.CheckState){
+                                       if (l == TypeManager.int32_type || l == TypeManager.int64_type)
+                                               opcode = OpCodes.Add_Ovf;
+                                       else if (l==TypeManager.uint32_type || l==TypeManager.uint64_type)
+                                               opcode = OpCodes.Add_Ovf_Un;
+                                       else
+                                               opcode = OpCodes.Mul;
+                               } else
+                                       opcode = OpCodes.Add;
+                               break;
+
+                       case Operator.Subtraction:
+                               if (ec.CheckState){
+                                       if (l == TypeManager.int32_type || l == TypeManager.int64_type)
+                                               opcode = OpCodes.Sub_Ovf;
+                                       else if (l==TypeManager.uint32_type || l==TypeManager.uint64_type)
+                                               opcode = OpCodes.Sub_Ovf_Un;
+                                       else
+                                               opcode = OpCodes.Sub;
+                               } else
+                                       opcode = OpCodes.Sub;
+                               break;
+
+                       case Operator.RightShift:
+                               opcode = OpCodes.Shr;
+                               break;
+                               
+                       case Operator.LeftShift:
+                               opcode = OpCodes.Shl;
+                               break;
+
+                       case Operator.Equality:
+                               opcode = OpCodes.Ceq;
+                               break;
+
+                       case Operator.Inequality:
+                               ec.ig.Emit (OpCodes.Ceq);
+                               ec.ig.Emit (OpCodes.Ldc_I4_0);
+                               
+                               opcode = OpCodes.Ceq;
+                               break;
+
+                       case Operator.LessThan:
+                               opcode = OpCodes.Clt;
+                               break;
+
+                       case Operator.GreaterThan:
+                               opcode = OpCodes.Cgt;
+                               break;
+
+                       case Operator.LessThanOrEqual:
+                               ec.ig.Emit (OpCodes.Cgt);
+                               ec.ig.Emit (OpCodes.Ldc_I4_0);
+                               
+                               opcode = OpCodes.Ceq;
+                               break;
+
+                       case Operator.GreaterThanOrEqual:
+                               ec.ig.Emit (OpCodes.Clt);
+                               ec.ig.Emit (OpCodes.Ldc_I4_1);
+                               
+                               opcode = OpCodes.Sub;
+                               break;
+
+                       case Operator.LogicalOr:
+                       case Operator.BitwiseOr:
+                               opcode = OpCodes.Or;
+                               break;
+
+                       case Operator.LogicalAnd:
+                       case Operator.BitwiseAnd:
+                               opcode = OpCodes.And;
+                               break;
+
+                       case Operator.ExclusiveOr:
+                               opcode = OpCodes.Xor;
+                               break;
+
+                       default:
+                               throw new Exception ("This should not happen: Operator = "
+                                                    + oper.ToString ());
+                       }
+
+                       ig.Emit (opcode);
+               }
+       }
+
+       public class Conditional : Expression {
+               Expression expr, trueExpr, falseExpr;
+               Location l;
+               
+               public Conditional (Expression expr, Expression trueExpr, Expression falseExpr, Location l)
+               {
+                       this.expr = expr;
+                       this.trueExpr = trueExpr;
+                       this.falseExpr = falseExpr;
+                       this.l = l;
+               }
+
+               public Expression Expr {
+                       get {
+                               return expr;
+                       }
+               }
+
+               public Expression TrueExpr {
+                       get {
+                               return trueExpr;
+                       }
+               }
+
+               public Expression FalseExpr {
+                       get {
+                               return falseExpr;
+                       }
+               }
+
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       expr = expr.Resolve (tc);
+
+                       if (expr.Type != TypeManager.bool_type)
+                               expr = Expression.ConvertImplicitRequired (
+                                       tc, expr, TypeManager.bool_type, l);
+                       
+                       trueExpr = trueExpr.Resolve (tc);
+                       falseExpr = falseExpr.Resolve (tc);
+
+                       if (expr == null || trueExpr == null || falseExpr == null)
+                               return null;
+                       
+                       if (trueExpr.Type == falseExpr.Type)
+                               type = trueExpr.Type;
+                       else {
+                               Expression conv;
+
+                               //
+                               // First, if an implicit conversion exists from trueExpr
+                               // to falseExpr, then the result type is of type falseExpr.Type
+                               //
+                               conv = ConvertImplicit (tc, trueExpr, falseExpr.Type, l);
+                               if (conv != null){
+                                       type = falseExpr.Type;
+                                       trueExpr = conv;
+                               } else if ((conv = ConvertImplicit (tc,falseExpr,trueExpr.Type,l)) != null){
+                                       type = trueExpr.Type;
+                                       falseExpr = conv;
+                               } else {
+                                       Error (tc, 173, l, "The type of the conditional expression can " +
+                                              "not be computed because there is no implicit conversion" +
+                                              " from `" + TypeManager.CSharpName (trueExpr.Type) + "'" +
+                                              " and `" + TypeManager.CSharpName (falseExpr.Type) + "'");
+                                       return null;
+                               }
+                       }
+
+                       eclass = ExprClass.Value;
+                       return this;
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       ILGenerator ig = ec.ig;
+                       Label false_target = ig.DefineLabel ();
+                       Label end_target = ig.DefineLabel ();
+
+                       expr.Emit (ec);
+                       ig.Emit (OpCodes.Brfalse, false_target);
+                       trueExpr.Emit (ec);
+                       ig.Emit (OpCodes.Br, end_target);
+                       ig.MarkLabel (false_target);
+                       falseExpr.Emit (ec);
+                       ig.MarkLabel (end_target);
+               }
+       }
+
+       public class SimpleName : Expression {
+               public readonly string Name;
+               public readonly Location Location;
+               
+               public SimpleName (string name, Location l)
+               {
+                       Name = name;
+                       Location = l;
+               }
+
+               //
+               // Checks whether we are trying to access an instance
+               // property, method or field from a static body.
+               //
+               Expression MemberStaticCheck (Report r, Expression e)
+               {
+                       if (e is FieldExpr){
+                               FieldInfo fi = ((FieldExpr) e).FieldInfo;
+                               
+                               if (!fi.IsStatic){
+                                       r.Error (120,
+                                                "An object reference is required " +
+                                                "for the non-static field `"+Name+"'");
+                                       return null;
+                               }
+                       } else if (e is MethodGroupExpr){
+                               // FIXME: Pending reorganization of MemberLookup
+                               // Basically at this point we should have the
+                               // best match already selected for us, and
+                               // we should only have to check a *single*
+                               // Method for its static on/off bit.
+                               return e;
+                       } else if (e is PropertyExpr){
+                               if (!((PropertyExpr) e).IsStatic){
+                                       r.Error (120,
+                                                "An object reference is required " +
+                                                "for the non-static property access `"+
+                                                Name+"'");
+                                       return null;
+                               }
+                       }
+
+                       return e;
+               }
+               
+               //
+               // 7.5.2: Simple Names. 
+               //
+               // Local Variables and Parameters are handled at
+               // parse time, so they never occur as SimpleNames.
+               //
+               Expression ResolveSimpleName (TypeContainer tc)
+               {
+                       Expression e;
+                       Report r = tc.RootContext.Report;
+
+                       e = MemberLookup (tc, tc.TypeBuilder, Name, true);
+                       if (e != null){
+                               if (e is TypeExpr)
+                                       return e;
+                               else if (e is FieldExpr){
+                                       FieldExpr fe = (FieldExpr) e;
+
+                                       if (!fe.FieldInfo.IsStatic)
+                                               fe.Instance = new This ();
+                               }
+                               
+                               if ((tc.ModFlags & Modifiers.STATIC) != 0)
+                                       return MemberStaticCheck (r, e);
+                               else
+                                       return e;
+                       }
+
+                       //
+                       // Do step 3 of the Simple Name resolution.
+                       //
+                       // FIXME: implement me.
+
+                       Error (tc, 103, Location, "The name `" + Name + "' does not exist in the class `" +
+                              tc.Name + "'");
+
+                       return null;
+               }
+               
+               //
+               // SimpleName needs to handle a multitude of cases:
+               //
+               // simple_names and qualified_identifiers are placed on
+               // the tree equally.
+               //
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       if (Name.IndexOf (".") != -1)
+                               return ResolveMemberAccess (tc, Name);
+                       else
+                               return ResolveSimpleName (tc);
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       throw new Exception ("SimpleNames should be gone from the tree");
+               }
+       }
+
+       // <summary>
+       //   A simple interface that should be implemeneted by LValues
+       // </summary>
+       public interface LValue {
+
+               // <summary>
+               //   The Store method should store the contents of the top
+               //   of the stack into the storage that is implemented by
+               //   the particular implementation of LValue
+               // </summary>
+               void Store     (EmitContext ec);
+
+               // <summary>
+               //   The AddressOf method should generate code that loads
+               //   the address of the LValue and leaves it on the stack
+               // </summary>
+               void AddressOf (EmitContext ec);
+       }
+       
+       public class LocalVariableReference : Expression, LValue {
+               public readonly string Name;
+               public readonly Block Block;
+               
+               public LocalVariableReference (Block block, string name)
+               {
+                       Block = block;
+                       Name = name;
+                       eclass = ExprClass.Variable;
+               }
+
+               public VariableInfo VariableInfo {
+                       get {
+                               return Block.GetVariableInfo (Name);
+                       }
+               }
+               
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       VariableInfo vi = Block.GetVariableInfo (Name);
+
+                       type = vi.VariableType;
+                       return this;
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       VariableInfo vi = VariableInfo;
+                       ILGenerator ig = ec.ig;
+                       int idx = vi.Idx;
+
+                       vi.Used = true;
+                       
+                       switch (idx){
+                       case 0:
+                               ig.Emit (OpCodes.Ldloc_0);
+                               break;
+                               
+                       case 1:
+                               ig.Emit (OpCodes.Ldloc_1);
+                               break;
+
+                       case 2:
+                               ig.Emit (OpCodes.Ldloc_2);
+                               break;
+
+                       case 3:
+                               ig.Emit (OpCodes.Ldloc_3);
+                               break;
+
+                       default:
+                               if (idx <= 255)
+                                       ig.Emit (OpCodes.Ldloc_S, (byte) idx);
+                               else
+                                       ig.Emit (OpCodes.Ldloc, idx);
+                               break;
+                       }
+               }
+
+               public void Store (EmitContext ec)
+               {
+                       ILGenerator ig = ec.ig;
+                       VariableInfo vi = VariableInfo;
+                       int idx = vi.Idx;
+
+                       vi.Assigned = true;
+                       switch (idx){
+                       case 0:
+                               ig.Emit (OpCodes.Stloc_0);
+                               break;
+                               
+                       case 1:
+                               ig.Emit (OpCodes.Stloc_1);
+                               break;
+                               
+                       case 2:
+                               ig.Emit (OpCodes.Stloc_2);
+                               break;
+                               
+                       case 3:
+                               ig.Emit (OpCodes.Stloc_3);
+                               break;
+                               
+                       default:
+                               if (idx <= 255)
+                                       ig.Emit (OpCodes.Stloc_S, (byte) idx);
+                               else
+                                       ig.Emit (OpCodes.Stloc, idx);
+                               break;
+                       }
+               }
+
+               public void AddressOf (EmitContext ec)
+               {
+                       VariableInfo vi = VariableInfo;
+                       int idx = vi.Idx;
+
+                       vi.Used = true;
+                       vi.Assigned = true;
+                       
+                       if (idx <= 255)
+                               ec.ig.Emit (OpCodes.Ldloca_S, (byte) idx);
+                       else
+                               ec.ig.Emit (OpCodes.Ldloca, idx);
+               }
+       }
+
+       public class ParameterReference : Expression, LValue {
+               public readonly Parameters Pars;
+               public readonly String Name;
+               public readonly int Idx;
+               
+               public ParameterReference (Parameters pars, int idx, string name)
+               {
+                       Pars = pars;
+                       Idx  = idx;
+                       Name = name;
+                       eclass = ExprClass.Variable;
+               }
+
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       Type [] types = Pars.GetParameterInfo (tc);
+
+                       type = types [Idx];
+
+                       return this;
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       if (Idx <= 255)
+                               ec.ig.Emit (OpCodes.Ldarg_S, (byte) Idx);
+                       else
+                               ec.ig.Emit (OpCodes.Ldarg, Idx);
+               }
+
+               public void Store (EmitContext ec)
+               {
+                       if (Idx <= 255)
+                               ec.ig.Emit (OpCodes.Starg_S, (byte) Idx);
+                       else
+                               ec.ig.Emit (OpCodes.Starg, Idx);
+                       
+               }
+
+               public void AddressOf (EmitContext ec)
+               {
+                       if (Idx <= 255)
+                               ec.ig.Emit (OpCodes.Ldarga_S, (byte) Idx);
+                       else
+                               ec.ig.Emit (OpCodes.Ldarga, Idx);
+               }
+       }
+       
+       // <summary>
+       //   Used for arguments to New(), Invocation()
+       // </summary>
+       public class Argument {
+               public enum AType {
+                       Expression,
+                       Ref,
+                       Out
+               };
+
+               public readonly AType Type;
+               Expression expr;
+
+               public Argument (Expression expr, AType type)
+               {
+                       this.expr = expr;
+                       this.Type = type;
+               }
+
+               public Expression Expr {
+                       get {
+                               return expr;
+                       }
+
+                       set {
+                               expr = value;
+                       }
+               }
+
+               public bool Resolve (TypeContainer tc)
+               {
+                       expr = expr.Resolve (tc);
+
+                       return expr != null;
+               }
+
+               public void Emit (EmitContext ec)
+               {
+                       expr.Emit (ec);
+               }
+       }
+
+       // <summary>
+       //   Invocation of methods or delegates.
+       // </summary>
+       public class Invocation : ExpressionStatement {
+               public readonly ArrayList Arguments;
+               public readonly Location Location;
+               
+               Expression expr;
+               MethodBase method = null;
+                       
+               static Hashtable method_parameter_cache;
+
+               static Invocation ()
+               {
+                       method_parameter_cache = new Hashtable ();
+               }
+                       
+               //
+               // arguments is an ArrayList, but we do not want to typecast,
+               // as it might be null.
+               //
+               // FIXME: only allow expr to be a method invocation or a
+               // delegate invocation (7.5.5)
+               //
+               public Invocation (Expression expr, ArrayList arguments, Location l)
+               {
+                       this.expr = expr;
+                       Arguments = arguments;
+                       Location = l;
+               }
+
+               public Expression Expr {
+                       get {
+                               return expr;
+                       }
+               }
+
+               // <summary>
+               //   Returns the Parameters (a ParameterData interface) for the
+               //   Method `mb'
+               // </summary>
+               static ParameterData GetParameterData (MethodBase mb)
+               {
+                       object pd = method_parameter_cache [mb];
+
+                       if (pd != null)
+                               return (ParameterData) pd;
+
+                       if (mb is MethodBuilder || mb is ConstructorBuilder){
+                               MethodCore mc = TypeContainer.LookupMethodByBuilder (mb);
+
+                               InternalParameters ip = mc.ParameterInfo;
+                               method_parameter_cache [mb] = ip;
+
+                               return (ParameterData) ip;
+                       } else {
+                               ParameterInfo [] pi = mb.GetParameters ();
+                               ReflectionParameters rp = new ReflectionParameters (pi);
+                               method_parameter_cache [mb] = rp;
+
+                               return (ParameterData) rp;
+                       }
+               }
+
+               // <summary>
+               //   Tells whether a user defined conversion from Type `from' to
+               //   Type `to' exists.
+               //
+               //   FIXME: we could implement a cache here. 
+               // </summary>
+               static bool ConversionExists (TypeContainer tc, Type from, Type to)
+               {
+                       // Locate user-defined implicit operators
+
+                       Expression mg;
+                       
+                       mg = MemberLookup (tc, to, "op_Implicit", false);
+
+                       if (mg != null) {
+                               MethodGroupExpr me = (MethodGroupExpr) mg;
+                               
+                               for (int i = me.Methods.Length; i > 0;) {
+                                       i--;
+                                       MethodBase mb = me.Methods [i];
+                                       ParameterData pd = GetParameterData (mb);
+                                       
+                                       if (from == pd.ParameterType (0))
+                                               return true;
+                               }
+                       }
+
+                       mg = MemberLookup (tc, from, "op_Implicit", false);
+
+                       if (mg != null) {
+                               MethodGroupExpr me = (MethodGroupExpr) mg;
+
+                               for (int i = me.Methods.Length; i > 0;) {
+                                       i--;
+                                       MethodBase mb = me.Methods [i];
+                                       MethodInfo mi = (MethodInfo) mb;
+                                       
+                                       if (mi.ReturnType == to)
+                                               return true;
+                               }
+                       }
+                       
+                       return false;
+               }
+               
+               // <summary>
+               //  Determines "better conversion" as specified in 7.4.2.3
+               //  Returns : 1 if a->p is better
+               //            0 if a->q or neither is better 
+               // </summary>
+               static int BetterConversion (TypeContainer tc, Argument a, Type p, Type q, bool use_standard)
+               {
+                       
+                       Type argument_type = a.Expr.Type;
+                       Expression argument_expr = a.Expr;
+
+                       if (argument_type == null)
+                               throw new Exception ("Expression of type " + a.Expr + " does not resolve its type");
+
+                       if (p == q)
+                               return 0;
+                       
+                       if (argument_type == p)
+                               return 1;
+
+                       if (argument_type == q)
+                               return 0;
+
+                       //
+                       // Now probe whether an implicit constant expression conversion
+                       // can be used.
+                       //
+                       // An implicit constant expression conversion permits the following
+                       // conversions:
+                       //
+                       //    * A constant-expression of type `int' can be converted to type
+                       //      sbyte, byute, short, ushort, uint, ulong provided the value of
+                       //      of the expression is withing the range of the destination type.
+                       //
+                       //    * A constant-expression of type long can be converted to type
+                       //      ulong, provided the value of the constant expression is not negative
+                       //
+                       // FIXME: Note that this assumes that constant folding has
+                       // taken place.  We dont do constant folding yet.
+                       //
+
+                       if (argument_expr is IntLiteral){
+                               IntLiteral ei = (IntLiteral) argument_expr;
+                               int value = ei.Value;
+                               
+                               if (p == TypeManager.sbyte_type){
+                                       if (value >= SByte.MinValue && value <= SByte.MaxValue)
+                                               return 1;
+                               } else if (p == TypeManager.byte_type){
+                                       if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
+                                               return 1;
+                               } else if (p == TypeManager.short_type){
+                                       if (value >= Int16.MinValue && value <= Int16.MaxValue)
+                                               return 1;
+                               } else if (p == TypeManager.ushort_type){
+                                       if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
+                                               return 1;
+                               } else if (p == TypeManager.uint32_type){
+                                       //
+                                       // we can optimize this case: a positive int32
+                                       // always fits on a uint32
+                                       //
+                                       if (value >= 0)
+                                               return 1;
+                               } else if (p == TypeManager.uint64_type){
+                                       //
+                                       // we can optimize this case: a positive int32
+                                       // always fits on a uint64
+                                       //
+                                       if (value >= 0)
+                                               return 1;
+                               }
+                       } else if (argument_type == TypeManager.int64_type && argument_expr is LongLiteral){
+                               LongLiteral ll = (LongLiteral) argument_expr;
+                               
+                               if (p == TypeManager.uint64_type){
+                                       if (ll.Value > 0)
+                                               return 1;
+                               }
+                       }
+
+                       if (q == null) {
+
+                               Expression tmp;
+
+                               if (use_standard)
+                                       tmp = ConvertImplicitStandard (tc, argument_expr, p, Location.Null);
+                               else
+                                       tmp = ConvertImplicit (tc, argument_expr, p, Location.Null);
+
+                               if (tmp != null)
+                                       return 1;
+                               else
+                                       return 0;
+
+                       }
+
+                       if (ConversionExists (tc, p, q) == true &&
+                           ConversionExists (tc, q, p) == false)
+                               return 1;
+
+                       if (p == TypeManager.sbyte_type)
+                               if (q == TypeManager.byte_type || q == TypeManager.ushort_type ||
+                                   q == TypeManager.uint32_type || q == TypeManager.uint64_type)
+                                       return 1;
+
+                       if (p == TypeManager.short_type)
+                               if (q == TypeManager.ushort_type || q == TypeManager.uint32_type ||
+                                   q == TypeManager.uint64_type)
+                                       return 1;
+
+                       if (p == TypeManager.int32_type)
+                               if (q == TypeManager.uint32_type || q == TypeManager.uint64_type)
+                                       return 1;
+
+                       if (p == TypeManager.int64_type)
+                               if (q == TypeManager.uint64_type)
+                                       return 1;
+
+                       return 0;
+               }
+               
+               // <summary>
+               //  Determines "Better function" and returns an integer indicating :
+               //  0 if candidate ain't better
+               //  1 if candidate is better than the current best match
+               // </summary>
+               static int BetterFunction (TypeContainer tc, ArrayList args,
+                                          MethodBase candidate, MethodBase best,
+                                          bool use_standard)
+               {
+                       ParameterData candidate_pd = GetParameterData (candidate);
+                       ParameterData best_pd;
+                       int argument_count;
+
+                       if (args == null)
+                               argument_count = 0;
+                       else
+                               argument_count = args.Count;
+
+                       if (candidate_pd.Count == 0 && argument_count == 0)
+                               return 1;
+
+                       if (best == null) {
+                               if (candidate_pd.Count == argument_count) {
+                                       int x = 0;
+                                       for (int j = argument_count; j > 0;) {
+                                               j--;
+                                               
+                                               Argument a = (Argument) args [j];
+                                               
+                                               x = BetterConversion (
+                                                       tc, a, candidate_pd.ParameterType (j), null,
+                                                       use_standard);
+                                               
+                                               if (x <= 0)
+                                                       break;
+                                       }
+                                       
+                                       if (x > 0)
+                                               return 1;
+                                       else
+                                               return 0;
+                                       
+                               } else
+                                       return 0;
+                       }
+
+                       best_pd = GetParameterData (best);
+
+                       if (candidate_pd.Count == argument_count && best_pd.Count == argument_count) {
+                               int rating1 = 0, rating2 = 0;
+                               
+                               for (int j = argument_count; j > 0;) {
+                                       j--;
+                                       int x, y;
+                                       
+                                       Argument a = (Argument) args [j];
+
+                                       x = BetterConversion (tc, a, candidate_pd.ParameterType (j),
+                                                             best_pd.ParameterType (j), use_standard);
+                                       y = BetterConversion (tc, a, best_pd.ParameterType (j),
+                                                             candidate_pd.ParameterType (j), use_standard);
+                                       
+                                       rating1 += x;
+                                       rating2 += y;
+                               }
+
+                               if (rating1 > rating2)
+                                       return 1;
+                               else
+                                       return 0;
+                       } else
+                               return 0;
+                       
+               }
+
+               public static string FullMethodDesc (MethodBase mb)
+               {
+                       StringBuilder sb = new StringBuilder (mb.Name);
+                       ParameterData pd = GetParameterData (mb);
+                       
+                       sb.Append (" (");
+                       for (int i = pd.Count; i > 0;) {
+                               i--;
+                               sb.Append (TypeManager.CSharpName (pd.ParameterType (i)));
+                               if (i != 0)
+                                       sb.Append (",");
+                       }
+                       
+                       sb.Append (")");
+                       return sb.ToString ();
+               }
+
+               public static MethodGroupExpr MakeUnionSet (Expression mg1, Expression mg2)
+               {
+
+                       if (mg1 != null || mg2 != null) {
+                                       
+                               MethodGroupExpr left_set = null, right_set = null;
+                               int length1 = 0, length2 = 0;
+                               
+                               if (mg1 != null) {
+                                       left_set = (MethodGroupExpr) mg1;
+                                       length1 = left_set.Methods.Length;
+                               }
+                               
+                               if (mg2 != null) {
+                                       right_set = (MethodGroupExpr) mg2;
+                                       length2 = right_set.Methods.Length;
+                               }
+                               
+                               MemberInfo [] miset = new MemberInfo [length1 + length2];
+                               if (left_set != null)
+                                       left_set.Methods.CopyTo (miset, 0);
+                               if (right_set != null)
+                                       right_set.Methods.CopyTo (miset, length1);
+                               
+                               MethodGroupExpr union = new MethodGroupExpr (miset);
+
+                               return union;
+                               
+                       }
+
+                       return null;
+
+               }
+
+               // <summary>
+               //   Find the Applicable Function Members (7.4.2.1)
+               //
+               //   me: Method Group expression with the members to select.
+               //       it might contain constructors or methods (or anything
+               //       that maps to a method).
+               //
+               //   Arguments: ArrayList containing resolved Argument objects.
+               //
+               //   loc: The location if we want an error to be reported, or a Null
+               //        location for "probing" purposes.
+               //
+               //   inside_user_defined: controls whether OverloadResolve should use the 
+               //   ConvertImplicit or ConvertImplicitStandard during overload resolution.
+               //
+               //   Returns: The MethodBase (either a ConstructorInfo or a MethodInfo)
+               //            that is the best match of me on Arguments.
+               //
+               // </summary>
+               public static MethodBase OverloadResolve (TypeContainer tc, MethodGroupExpr me,
+                                                         ArrayList Arguments, Location loc,
+                                                         bool use_standard)
+               {
+                       ArrayList afm = new ArrayList ();
+                       int best_match_idx = -1;
+                       MethodBase method = null;
+                       int argument_count;
+                       
+                       for (int i = me.Methods.Length; i > 0; ){
+                               i--;
+                               MethodBase candidate  = me.Methods [i];
+                               int x;
+
+                               x = BetterFunction (tc, Arguments, candidate, method, use_standard);
+                               
+                               if (x == 0)
+                                       continue;
+                               else {
+                                       best_match_idx = i;
+                                       method = me.Methods [best_match_idx];
+                               }
+                       }
+
+                       if (Arguments == null)
+                               argument_count = 0;
+                       else
+                               argument_count = Arguments.Count;
+                       
+                       ParameterData pd;
+                       
+                       // Now we see if we can at least find a method with the same number of arguments
+                       // and then try doing implicit conversion on the arguments
+                       if (best_match_idx == -1) {
+                               
+                               for (int i = me.Methods.Length; i > 0;) {
+                                       i--;
+                                       MethodBase mb = me.Methods [i];
+                                       pd = GetParameterData (mb);
+                                       
+                                       if (pd.Count == argument_count) {
+                                               best_match_idx = i;
+                                               method = me.Methods [best_match_idx];
+                                               break;
+                                       } else
+                                               continue;
+                               }
+
+                       }
+
+                       if (method == null)
+                               return null;
+
+                       // And now convert implicitly, each argument to the required type
+                       
+                       pd = GetParameterData (method);
+
+                       for (int j = argument_count; j > 0;) {
+                               j--;
+                               Argument a = (Argument) Arguments [j];
+                               Expression a_expr = a.Expr;
+                               Type parameter_type = pd.ParameterType (j);
+                               
+                               if (a_expr.Type != parameter_type){
+                                       Expression conv;
+
+                                       if (use_standard)
+                                               conv = ConvertImplicitStandard (tc, a_expr, parameter_type,
+                                                                               Location.Null);
+                                       else
+                                               conv = ConvertImplicit (tc, a_expr, parameter_type,
+                                                                       Location.Null);
+
+                                       if (conv == null){
+                                               if (!Location.IsNull (loc)) {
+                                                       Error (tc, 1502, loc,
+                                                              "The best overloaded match for method '" + FullMethodDesc (method) +
+                                                              "' has some invalid arguments");
+                                                       Error (tc, 1503, loc,
+                                                              "Argument " + (j+1) +
+                                                              ": Cannot convert from '" + TypeManager.CSharpName (a_expr.Type)
+                                                              + "' to '" + TypeManager.CSharpName (pd.ParameterType (j)) + "'");
+                                               }
+                                               return null;
+                                       }
+                                       //
+                                       // Update the argument with the implicit conversion
+                                       //
+                                       if (a_expr != conv)
+                                               a.Expr = conv;
+                               }
+                       }
+                       
+                       return method;
+               }
+
+               public static MethodBase OverloadResolve (TypeContainer tc, MethodGroupExpr me,
+                                                         ArrayList Arguments, Location loc)
+               {
+                       return OverloadResolve (tc, me, Arguments, loc, false);
+               }
+                       
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       //
+                       // First, resolve the expression that is used to
+                       // trigger the invocation
+                       //
+                       this.expr = expr.Resolve (tc);
+                       if (this.expr == null)
+                               return null;
+
+                       if (!(this.expr is MethodGroupExpr)){
+                               report118 (tc, Location, this.expr, "method group");
+                               return null;
+                       }
+
+                       //
+                       // Next, evaluate all the expressions in the argument list
+                       //
+                       if (Arguments != null){
+                               for (int i = Arguments.Count; i > 0;){
+                                       --i;
+                                       Argument a = (Argument) Arguments [i];
+
+                                       if (!a.Resolve (tc))
+                                               return null;
+                               }
+                       }
+
+                       method = OverloadResolve (tc, (MethodGroupExpr) this.expr, Arguments,
+                                                 Location);
+
+                       if (method == null){
+                               Error (tc, -6, Location,
+                                      "Could not find any applicable function for this argument list");
+                               return null;
+                       }
+
+                       if (method is MethodInfo)
+                               type = ((MethodInfo)method).ReturnType;
+
+                       eclass = ExprClass.Value;
+                       return this;
+               }
+
+               public static void EmitArguments (EmitContext ec, MethodBase method, ArrayList Arguments)
+               {
+                       int top;
+
+                       if (Arguments != null)
+                               top = Arguments.Count;
+                       else
+                               top = 0;
+
+                       for (int i = 0; i < top; i++){
+                               Argument a = (Argument) Arguments [i];
+
+                               a.Emit (ec);
+                       }
+               }
+               
+               public override void Emit (EmitContext ec)
+               {
+                       bool is_static = method.IsStatic;
+
+                       if (!is_static){
+                               MethodGroupExpr mg = (MethodGroupExpr) this.expr;
+
+                               //
+                               // If this is ourselves, push "this"
+                               //
+                               if (mg.InstanceExpression == null){
+                                       ec.ig.Emit (OpCodes.Ldarg_0);
+                               } else {
+                                       //
+                                       // Push the instance expression
+                                       //
+                                       mg.InstanceExpression.Emit (ec);
+                               }
+                       }
+
+                       if (Arguments != null)
+                               EmitArguments (ec, method, Arguments);
+
+                       if (is_static){
+                               if (method is MethodInfo)
+                                       ec.ig.Emit (OpCodes.Call, (MethodInfo) method);
+                               else
+                                       ec.ig.Emit (OpCodes.Call, (ConstructorInfo) method);
+                       } else {
+                               if (method is MethodInfo)
+                                       ec.ig.Emit (OpCodes.Callvirt, (MethodInfo) method);
+                               else
+                                       ec.ig.Emit (OpCodes.Callvirt, (ConstructorInfo) method);
+                       }
+               }
+
+               public override void EmitStatement (EmitContext ec)
+               {
+                       Emit (ec);
+
+                       // 
+                       // Pop the return value if there is one
+                       //
+                       if (method is MethodInfo){
+                               if (((MethodInfo)method).ReturnType != TypeManager.void_type)
+                                       ec.ig.Emit (OpCodes.Pop);
+                       }
+               }
+       }
+
+       public class New : ExpressionStatement {
+
+               public enum NType {
+                       Object,
+                       Array
+               };
+
+               public readonly NType     NewType;
+               public readonly ArrayList Arguments;
+               public readonly string    RequestedType;
+               // These are for the case when we have an array
+               public readonly string    Rank;
+               public readonly ArrayList Indices;
+               public readonly ArrayList Initializers;
+
+               Location Location;
+               MethodBase method = null;
+
+               public New (string requested_type, ArrayList arguments, Location loc)
+               {
+                       RequestedType = requested_type;
+                       Arguments = arguments;
+                       NewType = NType.Object;
+                       Location = loc;
+               }
+
+               public New (string requested_type, ArrayList exprs, string rank, ArrayList initializers, Location loc)
+               {
+                       RequestedType = requested_type;
+                       Indices       = exprs;
+                       Rank          = rank;
+                       Initializers  = initializers;
+                       NewType       = NType.Array;
+                       Location      = loc;
+               }
+               
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       type = tc.LookupType (RequestedType, false);
+
+                       if (type == null)
+                               return null;
+
+                       Expression ml;
+
+                       ml = MemberLookup (tc, type, ".ctor", false,
+                                          MemberTypes.Constructor, AllBindingsFlags);
+
+                       if (! (ml is MethodGroupExpr)){
+                               //
+                               // FIXME: Find proper error
+                               //
+                               report118 (tc, Location, ml, "method group");
+                               return null;
+                       }
+                       
+                       if (Arguments != null){
+                               for (int i = Arguments.Count; i > 0;){
+                                       --i;
+                                       Argument a = (Argument) Arguments [i];
+
+                                       if (!a.Resolve (tc))
+                                               return null;
+                               }
+                       }
+
+                       method = Invocation.OverloadResolve (tc, (MethodGroupExpr) ml, Arguments,
+                                                            Location);
+
+                       if (method == null) {
+                               Error (tc, -6, Location,
+                                      "New invocation: Can not find a constructor for this argument list");
+                               return null;
+                       }
+
+                       eclass = ExprClass.Value;
+                       return this;
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       Invocation.EmitArguments (ec, method, Arguments);
+                       ec.ig.Emit (OpCodes.Newobj, (ConstructorInfo) method);
+               }
+
+               public override void EmitStatement (EmitContext ec)
+               {
+                       Emit (ec);
+                       ec.ig.Emit (OpCodes.Pop);
+               }
+       }
+
+       //
+       // Represents the `this' construct
+       //
+       public class This : Expression, LValue {
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       eclass = ExprClass.Variable;
+                       type = tc.TypeBuilder;
+
+                       //
+                       // FIXME: Verify that this is only used in instance contexts.
+                       //
+                       return this;
+               }
+
+               public override void Emit (EmitContext ec)
+               {
+                       ec.ig.Emit (OpCodes.Ldarg_0);
+               }
+
+               public void Store (EmitContext ec)
+               {
+                       //
+                       // Assignment to the "this" variable.
+                       //
+                       // FIXME: Apparently this is a bug that we
+                       // must catch as `this' seems to be readonly ;-)
+                       //
+                       ec.ig.Emit (OpCodes.Starg, 0);
+               }
+
+               public void AddressOf (EmitContext ec)
+               {
+                       ec.ig.Emit (OpCodes.Ldarga_S, (byte) 0);
+               }
+       }
+
+       // <summary>
+       //   Implements the typeof operator
+       // </summary>
+       public class TypeOf : Expression {
+               public readonly string QueriedType;
+               Type typearg;
+               
+               public TypeOf (string queried_type)
+               {
+                       QueriedType = queried_type;
+               }
+
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       typearg = tc.LookupType (QueriedType, false);
+
+                       if (typearg == null)
+                               return null;
 
-               public enum Operator {
-                       Is, As
+                       type = TypeManager.type_type;
+                       eclass = ExprClass.Type;
+                       return this;
                }
-               
-               public Probe (Operator oper, Expression expr, string type)
+
+               public override void Emit (EmitContext ec)
                {
-                       this.oper = oper;
-                       this.type = type;
-                       this.expr = expr;
+                       ec.ig.Emit (OpCodes.Ldtoken, typearg);
+                       ec.ig.Emit (OpCodes.Call, TypeManager.system_type_get_type_from_handle);
                }
+       }
 
-               public Operator Oper {
-                       get {
-                               return oper;
-                       }
+       public class SizeOf : Expression {
+               public readonly string QueriedType;
+               
+               public SizeOf (string queried_type)
+               {
+                       this.QueriedType = queried_type;
                }
 
-               public Expression Expr {
-                       get {
-                               return expr;
-                       }
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       // FIXME: Implement;
+                       throw new Exception ("Unimplemented");
+                       // return this;
                }
 
-               public string ProbeType {
-                       get {
-                               return type;
-                       }
+               public override void Emit (EmitContext ec)
+               {
+                       throw new Exception ("Implement me");
                }
-                              
        }
-       
-       public class Cast : Expression {
-               string type;
+
+       public class MemberAccess : Expression {
+               public readonly string Identifier;
                Expression expr;
+               Expression member_lookup;
                
-               public Cast (string type, Expression expr)
+               public MemberAccess (Expression expr, string id)
                {
-                       this.type = type;
                        this.expr = expr;
-               }
-
-               public string TargetType {
-                       get {
-                               return type;
-                       }
+                       Identifier = id;
                }
 
                public Expression Expr {
                        get {
                                return expr;
                        }
-                       set {
-                               expr = value;
-                       }
                }
-       }
+               
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       Expression new_expression = expr.Resolve (tc);
 
-       public class Binary : Expression {
-               public enum Operator {
-                       Multiply, Divide, Modulo,
-                       Add, Substract,
-                       ShiftLeft, ShiftRight,
-                       LessThan, GreatherThan, LessOrEqual, GreatherOrEqual, 
-                       Equal, NotEqual,
-                       BitwiseAnd,
-                       ExclusiveOr,
-                       BitwiseOr,
-                       LogicalAnd,
-                       LogicalOr
+                       if (new_expression == null)
+                               return null;
+
+                       member_lookup = MemberLookup (tc, expr.Type, Identifier, false);
+
+                       if (member_lookup is MethodGroupExpr){
+                               MethodGroupExpr mg = (MethodGroupExpr) member_lookup;
+
+                               //
+                               // Bind the instance expression to it
+                               //
+                               // FIXME: This is a horrible way of detecting if it is
+                               // an instance expression.  Figure out how to fix this.
+                               //
+
+                               if (expr is LocalVariableReference ||
+                                   expr is ParameterReference ||
+                                   expr is FieldExpr)
+                                       mg.InstanceExpression = expr;
+                                       
+                               return member_lookup;
+                       } else if (member_lookup is FieldExpr){
+                               FieldExpr fe = (FieldExpr) member_lookup;
+
+                               fe.Instance = expr;
+
+                               return member_lookup;
+                       } else
+                               //
+                               // FIXME: This should generate the proper node
+                               // ie, for a Property Access, it should like call it
+                               // and stuff.
+
+                               return member_lookup;
                }
 
-               Operator oper;
-               Expression left, right;
-               
-               public Binary (Operator oper, Expression left, Expression right)
+               public override void Emit (EmitContext ec)
                {
-                       this.oper = oper;
-                       this.left = left;
-                       this.right = right;
+                       throw new Exception ("Should not happen I think");
                }
 
-               public Operator Oper {
-                       get {
-                               return oper;
-                       }
-                       set {
-                               oper = value;
-                       }
-               }
+       }
+
+       // <summary>
+       //   Nodes of type Namespace are created during the semantic
+       //   analysis to resolve member_access/qualified_identifier/simple_name
+       //   accesses.
+       //
+       //   They are born `resolved'. 
+       // </summary>
+       public class NamespaceExpr : Expression {
+               public readonly string Name;
                
-               public Expression Left {
-                       get {
-                               return left;
-                       }
-                       set {
-                               left = value;
-                       }
+               public NamespaceExpr (string name)
+               {
+                       Name = name;
+                       eclass = ExprClass.Namespace;
                }
 
-               public Expression Right {
-                       get {
-                               return right;
-                       }
-                       set {
-                               right = value;
-                       }
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       return this;
                }
-       }
 
-       public class Conditional : Expression {
-               Expression expr, trueExpr, falseExpr;
-               
-               public Conditional (Expression expr, Expression trueExpr, Expression falseExpr)
+               public override void Emit (EmitContext ec)
                {
-                       this.expr = expr;
-                       this.trueExpr = trueExpr;
-                       this.falseExpr = falseExpr;
+                       throw new Exception ("Namespace expressions should never be emitted");
                }
+       }
 
-               public Expression Expr {
-                       get {
-                               return expr;
-                       }
+       // <summary>
+       //   Fully resolved expression that evaluates to a type
+       // </summary>
+       public class TypeExpr : Expression {
+               public TypeExpr (Type t)
+               {
+                       Type = t;
+                       eclass = ExprClass.Type;
                }
 
-               public Expression TrueExpr {
-                       get {
-                               return trueExpr;
-                       }
+               override public Expression DoResolve (TypeContainer tc)
+               {
+                       return this;
                }
 
-               public Expression FalseExpr {
-                       get {
-                               return falseExpr;
-                       }
+               override public void Emit (EmitContext ec)
+               {
+                       throw new Exception ("Implement me");
                }
        }
 
-       public class SimpleName : Expression {
-               string name;
+       // <summary>
+       //   MethodGroup Expression.
+       //  
+       //   This is a fully resolved expression that evaluates to a type
+       // </summary>
+       public class MethodGroupExpr : Expression {
+               public readonly MethodBase [] Methods;
+               Expression instance_expression = null;
                
-               public SimpleName (string name)
+               public MethodGroupExpr (MemberInfo [] mi)
                {
-                       this.name = name;
+                       Methods = new MethodBase [mi.Length];
+                       mi.CopyTo (Methods, 0);
+                       eclass = ExprClass.MethodGroup;
                }
 
-               public string Name {
+               //
+               // `A method group may have associated an instance expression' 
+               // 
+               public Expression InstanceExpression {
                        get {
-                               return name;
+                               return instance_expression;
+                       }
+
+                       set {
+                               instance_expression = value;
                        }
                }
+               
+               override public Expression DoResolve (TypeContainer tc)
+               {
+                       return this;
+               }
+
+               override public void Emit (EmitContext ec)
+               {
+                       throw new Exception ("This should never be reached");
+               }
        }
        
-       public class LocalVariableReference : Expression {
-               string name;
-               Block block;
-               
-               public LocalVariableReference (Block block, string name)
+       //   Fully resolved expression that evaluates to a Field
+       // </summary>
+       public class FieldExpr : Expression, LValue {
+               public readonly FieldInfo FieldInfo;
+               public Expression Instance;
+                       
+               public FieldExpr (FieldInfo fi)
                {
-                       this.block = block;
-                       this.name = name;
+                       FieldInfo = fi;
+                       eclass = ExprClass.Variable;
+                       type = fi.FieldType;
                }
 
-               public Block Block {
-                       get {
-                               return block;
+               override public Expression DoResolve (TypeContainer tc)
+               {
+                       if (!FieldInfo.IsStatic){
+                               if (Instance == null){
+                                       throw new Exception ("non-static FieldExpr without instance var\n" +
+                                                            "You have to assign the Instance variable\n" +
+                                                            "Of the FieldExpr to set this\n");
+                               }
+
+                               Instance = Instance.Resolve (tc);
+                               if (Instance == null)
+                                       return null;
+                               
                        }
+                       return this;
                }
 
-               public string Name {
-                       get {
-                               return name;
+               override public void Emit (EmitContext ec)
+               {
+                       ILGenerator ig = ec.ig;
+
+                       if (FieldInfo.IsStatic)
+                               ig.Emit (OpCodes.Ldsfld, FieldInfo);
+                       else {
+                               Instance.Emit (ec);
+                               
+                               ig.Emit (OpCodes.Ldfld, FieldInfo);
                        }
                }
-       }
 
-       public class ParameterReference : Expression {
-               Parameters pars;
-               string name;
-               
-               public ParameterReference (Parameters pars, string name)
+               public void Store (EmitContext ec)
                {
-                       this.pars = pars;
-                       this.name = name;
+                       if (FieldInfo.IsStatic)
+                               ec.ig.Emit (OpCodes.Stsfld, FieldInfo);
+                       else
+                               ec.ig.Emit (OpCodes.Stfld, FieldInfo);
                }
 
-               public string Name {
-                       get {
-                               return name;
+               public void AddressOf (EmitContext ec)
+               {
+                       if (FieldInfo.IsStatic)
+                               ec.ig.Emit (OpCodes.Ldsflda, FieldInfo);
+                       else {
+                               Instance.Emit (ec);
+                               ec.ig.Emit (OpCodes.Ldflda, FieldInfo);
                        }
                }
        }
        
        // <summary>
-       //   Used for arguments to New(), Invocation()
+       //   Fully resolved expression that evaluates to a Property
        // </summary>
-       public class Argument {
-               public enum AType {
-                       Expression,
-                       Ref,
-                       Out
-               };
+       public class PropertyExpr : Expression {
+               public readonly PropertyInfo PropertyInfo;
+               public readonly bool IsStatic;
+               
+               public PropertyExpr (PropertyInfo pi)
+               {
+                       PropertyInfo = pi;
+                       eclass = ExprClass.PropertyAccess;
+                       IsStatic = false;
+                               
+                       MethodBase [] acc = pi.GetAccessors ();
 
-               AType type;
-               Expression expr;
+                       for (int i = 0; i < acc.Length; i++)
+                               if (acc [i].IsStatic)
+                                       IsStatic = true;
 
-               public Argument (Expression expr, AType type)
-               {
-                       this.expr = expr;
-                       this.type = type;
+                       type = pi.PropertyType;
                }
 
-               public Expression Expr {
-                       get {
-                               return expr;
-                       }
+               override public Expression DoResolve (TypeContainer tc)
+               {
+                       // We are born in resolved state. 
+                       return this;
                }
 
-               public AType Type {
-                       get {
-                               return type;
-                       }
+               override public void Emit (EmitContext ec)
+               {
+                       // FIXME: Implement;
+                       throw new Exception ("Unimplemented");
                }
        }
 
        // <summary>
-       //   Invocation of methods or delegates.
+       //   Fully resolved expression that evaluates to a Expression
        // </summary>
-       public class Invocation : Expression {
-               ArrayList arguments;
-               Expression expr;
-
-               //
-               // arguments is an ArrayList, but we do not want to typecast,
-               // as it might be null.
-               //
-               // FIXME: only allow expr to be a method invocation or a
-               // delegate invocation (7.5.5)
-               //
-               public Invocation (Expression expr, ArrayList arguments)
+       public class EventExpr : Expression {
+               public readonly EventInfo EventInfo;
+               
+               public EventExpr (EventInfo ei)
                {
-                       this.expr = expr;
-                       this.arguments = arguments;
+                       EventInfo = ei;
+                       eclass = ExprClass.EventAccess;
                }
 
-               public Expression Expr {
-                       get {
-                               return expr;
-                       }
+               override public Expression DoResolve (TypeContainer tc)
+               {
+                       // We are born in resolved state. 
+                       return this;
                }
 
-               public ArrayList Arguments {
-                       get {
-                               return arguments;
-                       }
+               override public void Emit (EmitContext ec)
+               {
+                       throw new Exception ("Implement me");
+                       // FIXME: Implement.
                }
        }
+       
+       public class CheckedExpr : Expression {
 
-       public class New : Expression {
-               ArrayList arguments;
-               string requested_type;
+               public Expression Expr;
 
-               public New (string requested_type, ArrayList arguments)
+               public CheckedExpr (Expression e)
                {
-                       this.requested_type = requested_type;
-                       this.arguments = arguments;
+                       Expr = e;
                }
-               
-               public ArrayList Arguments{
-                       get {
-                               return arguments;
-                       }
+
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       Expr = Expr.Resolve (tc);
+
+                       if (Expr == null)
+                               return null;
+
+                       eclass = Expr.ExprClass;
+                       type = Expr.Type;
+                       return this;
                }
-               
-               public string RequestedType {
-                       get {
-                               return requested_type;
-                       }
+
+               public override void Emit (EmitContext ec)
+               {
+                       bool last_check = ec.CheckState;
+                       
+                       ec.CheckState = true;
+                       Expr.Emit (ec);
+                       ec.CheckState = last_check;
                }
+               
        }
 
-       public class This : Expression {
-       }
+       public class UnCheckedExpr : Expression {
 
-       public class TypeOf : Expression {
-               string queried_type;
-               
-               public TypeOf (string queried_type)
+               public Expression Expr;
+
+               public UnCheckedExpr (Expression e)
                {
-                       this.queried_type = queried_type;
+                       Expr = e;
                }
 
-               public string QueriedType {
-                       get {
-                               return queried_type;
-                       }
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       Expr = Expr.Resolve (tc);
+
+                       if (Expr == null)
+                               return null;
+
+                       eclass = Expr.ExprClass;
+                       type = Expr.Type;
+                       return this;
                }
-       }
 
-       public class SizeOf : Expression {
-               string queried_type;
+               public override void Emit (EmitContext ec)
+               {
+                       bool last_check = ec.CheckState;
+                       
+                       ec.CheckState = false;
+                       Expr.Emit (ec);
+                       ec.CheckState = last_check;
+               }
                
-               public SizeOf (string queried_type)
+       }
+       
+       public class ElementAccess : Expression {
+               
+               public readonly ArrayList  Arguments;
+               public readonly Expression Expr;
+               
+               public ElementAccess (Expression e, ArrayList e_list)
                {
-                       this.queried_type = queried_type;
+                       Expr = e;
+                       Arguments = e_list;
                }
 
-               public string QueriedType {
-                       get {
-                               return queried_type;
-                       }
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       // FIXME: Implement;
+                       throw new Exception ("Unimplemented");
+                       // return this;
                }
+               
+               public override void Emit (EmitContext ec)
+               {
+                       // FIXME : Implement !
+                       throw new Exception ("Unimplemented");
+               }
+               
        }
+       
+       public class BaseAccess : Expression {
 
-       public class MemberAccess : Expression {
-               Expression expr;
-               string id;
+               public enum BaseAccessType {
+                       Member,
+                       Indexer
+               };
                
-               public MemberAccess (Expression expr, string id)
+               public readonly BaseAccessType BAType;
+               public readonly string         Member;
+               public readonly ArrayList      Arguments;
+
+               public BaseAccess (BaseAccessType t, string member, ArrayList args)
                {
-                       this.expr = expr;
-                       this.id = id;
+                       BAType = t;
+                       Member = member;
+                       Arguments = args;
+                       
                }
 
-               public Expression Expr {
-                       get {
-                               return expr;
-                       }
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       // FIXME: Implement;
+                       throw new Exception ("Unimplemented");
+                       // return this;
                }
 
-               public string Identifier {
-                       get {
-                               return id;
-                       }
+               public override void Emit (EmitContext ec)
+               {
+                       throw new Exception ("Unimplemented");
                }
        }
 
-       public class BuiltinTypeAccess : Expression {
-               string access_base;
-               string method;
+       public class UserImplicitCast : Expression {
+               MethodBase method;
+               ArrayList  arguments;
                
-               public BuiltinTypeAccess (string type, string method)
+               public UserImplicitCast (MethodInfo method, ArrayList arguments)
                {
-                       System.Console.WriteLine ("DUDE! This type should be fully resolved!");
-                       this.access_base = access_base;
                        this.method = method;
+                       this.arguments = arguments;
+                       type = method.ReturnType;
+                       eclass = ExprClass.Value;
                }
 
-               public string AccessBase {
-                       get {
-                               return access_base;
-                       }
+               public override Expression DoResolve (TypeContainer tc)
+               {
+                       //
+                       // We are born in a fully resolved state
+                       //
+                       return this;
                }
 
-               public string Method {
-                       get {
-                               return method;
-                       }
+               public override void Emit (EmitContext ec)
+               {
+                       ILGenerator ig = ec.ig;
+                       
+                       // Note that operators are static anyway
+                               
+                       if (arguments != null) 
+                               Invocation.EmitArguments (ec, method, arguments);
+                       
+                       if (method is MethodInfo)
+                               ig.Emit (OpCodes.Call, (MethodInfo) method);
+                       else
+                               ig.Emit (OpCodes.Call, (ConstructorInfo) method);
                }
+
        }
 }
-
-
-
-
-