X-Git-Url: http://wien.tomnetworks.com/gitweb/?a=blobdiff_plain;f=mcs%2Fmcs%2Fconstant.cs;h=c04ad0246df1417ee4d111d3245a9f5e4e2370c1;hb=7674f7142c1f8e30c32d8559d56f3bfc91387ea0;hp=536b0878583e23d133042df6bb34efebf41ba5fc;hpb=e2fdf31a2a565184dabf235a75dc8ab184fea4f2;p=mono.git

diff --git a/mcs/mcs/constant.cs b/mcs/mcs/constant.cs
old mode 100755
new mode 100644
index 536b0878583..c04ad0246df
--- a/mcs/mcs/constant.cs
+++ b/mcs/mcs/constant.cs
@@ -1,139 +1,2130 @@
 //
-// constant.cs: Constant expressions and constant folding.
+// constant.cs: Constants.
 //
 // Author:
 //   Miguel de Icaza (miguel@ximian.com)
+//   Marek Safar (marek.safar@seznam.cz)
 //
-// (C) 2001 Ximian, Inc.
-//
+// Copyright 2001-2003 Ximian, Inc.
+// Copyright 2003-2008 Novell, Inc.
 //
 
-namespace Mono.CSharp {
+using System;
+using System.Reflection.Emit;
+
+namespace Mono.CSharp {
+
+	/// <summary>
+	///   Base class for constants and literals.
+	/// </summary>
+	public abstract class Constant : Expression {
+
+		protected Constant (Location loc)
+		{
+			this.loc = loc;
+		}
+
+		/// <remarks>
+		///   This is different from ToString in that ToString
+		///   is supposed to be there for debugging purposes,
+		///   and is not guaranteed to be useful for anything else,
+		///   AsString() will provide something that can be used
+		///   for round-tripping C# code.  Maybe it can be used
+		///   for IL assembly as well.
+		/// </remarks>
+		public abstract string AsString ();
+
+		override public string ToString ()
+		{
+			return this.GetType ().Name + " (" + AsString () + ")";
+		}
+
+		/// <summary>
+		///  This is used to obtain the actual value of the literal
+		///  cast into an object.
+		/// </summary>
+		public abstract object GetValue ();
+
+		public virtual object GetTypedValue ()
+		{
+			return GetValue ();
+		}
+
+		public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
+		{
+			if (!expl && IsLiteral && 
+				(TypeManager.IsPrimitiveType (target) || type == TypeManager.decimal_type) &&
+				(TypeManager.IsPrimitiveType (type) || type == TypeManager.decimal_type)) {
+				ec.Report.Error (31, loc, "Constant value `{0}' cannot be converted to a `{1}'",
+					AsString (), TypeManager.CSharpName (target));
+			} else {
+				base.Error_ValueCannotBeConverted (ec, loc, target, expl);
+			}
+		}
+
+		public Constant ImplicitConversionRequired (ResolveContext ec, TypeSpec type, Location loc)
+		{
+			Constant c = ConvertImplicitly (ec, type);
+			if (c == null)
+				Error_ValueCannotBeConverted (ec, loc, type, false);
+
+			return c;
+		}
+
+		public virtual Constant ConvertImplicitly (ResolveContext rc, TypeSpec type)
+		{
+			if (this.type == type)
+				return this;
+
+			if (Convert.ImplicitNumericConversion (this, type) == null) 
+				return null;
+
+			bool fail;			
+			object constant_value = TypeManager.ChangeType (GetValue (), type, out fail);
+			if (fail){
+				//
+				// We should always catch the error before this is ever
+				// reached, by calling Convert.ImplicitStandardConversionExists
+				//
+				throw new InternalErrorException ("Missing constant conversion between `{0}' and `{1}'",
+				  TypeManager.CSharpName (Type), TypeManager.CSharpName (type));
+			}
+
+			return CreateConstant (rc, type, constant_value, loc);
+		}
+
+		//
+		//  Returns a constant instance based on Type
+		//
+		public static Constant CreateConstant (ResolveContext rc, TypeSpec t, object v, Location loc)
+		{
+			return CreateConstantFromValue (t, v, loc).Resolve (rc);
+		}
+
+		public static Constant CreateConstantFromValue (TypeSpec t, object v, Location loc)
+		{
+			if (t == TypeManager.int32_type)
+				return new IntConstant ((int) v, loc);
+			if (t == TypeManager.string_type)
+				return new StringConstant ((string) v, loc);
+			if (t == TypeManager.uint32_type)
+				return new UIntConstant ((uint) v, loc);
+			if (t == TypeManager.int64_type)
+				return new LongConstant ((long) v, loc);
+			if (t == TypeManager.uint64_type)
+				return new ULongConstant ((ulong) v, loc);
+			if (t == TypeManager.float_type)
+				return new FloatConstant ((float) v, loc);
+			if (t == TypeManager.double_type)
+				return new DoubleConstant ((double) v, loc);
+			if (t == TypeManager.short_type)
+				return new ShortConstant ((short)v, loc);
+			if (t == TypeManager.ushort_type)
+				return new UShortConstant ((ushort)v, loc);
+			if (t == TypeManager.sbyte_type)
+				return new SByteConstant ((sbyte)v, loc);
+			if (t == TypeManager.byte_type)
+				return new ByteConstant ((byte)v, loc);
+			if (t == TypeManager.char_type)
+				return new CharConstant ((char)v, loc);
+			if (t == TypeManager.bool_type)
+				return new BoolConstant ((bool) v, loc);
+			if (t == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) v, loc);
+			if (TypeManager.IsEnumType (t)) {
+				var real_type = EnumSpec.GetUnderlyingType (t);
+				return new EnumConstant (CreateConstantFromValue (real_type, v, loc).Resolve (null), t);
+			}
+			if (v == null) {
+				if (TypeManager.IsNullableType (t))
+					return Nullable.LiftedNull.Create (t, loc);
+
+				if (TypeManager.IsReferenceType (t))
+					return new NullConstant (t, loc);
+			}
+
+			throw new InternalErrorException ("Constant value `{0}' has unexpected underlying type `{1}'",
+				v, TypeManager.CSharpName (t));
+		}
+
+		public override Expression CreateExpressionTree (ResolveContext ec)
+		{
+			Arguments args = new Arguments (2);
+			args.Add (new Argument (this));
+			args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
+
+			return CreateExpressionFactoryCall (ec, "Constant", args);
+		}
+
+
+		/// <summary>
+		/// Maybe ConvertTo name is better. It tries to convert `this' constant to target_type.
+		/// It throws OverflowException 
+		/// </summary>
+		// DON'T CALL THIS METHOD DIRECTLY AS IT DOES NOT HANDLE ENUMS
+		public abstract Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type);
+
+		/// <summary>
+		///   Attempts to do a compile-time folding of a constant cast.
+		/// </summary>
+		public Constant TryReduce (ResolveContext ec, TypeSpec target_type, Location loc)
+		{
+			try {
+				return TryReduce (ec, target_type);
+			}
+			catch (OverflowException) {
+				if (ec.ConstantCheckState) {				
+					ec.Report.Error (221, loc, "Constant value `{0}' cannot be converted to a `{1}' (use `unchecked' syntax to override)",
+						GetValue ().ToString (), TypeManager.CSharpName (target_type));
+				} else {
+					Error_ValueCannotBeConverted (ec, loc, target_type, false);
+				}
+
+				return New.Constantify (target_type).Resolve (ec);
+			}
+		}
+
+		Constant TryReduce (ResolveContext ec, TypeSpec target_type)
+		{
+			if (Type == target_type)
+				return this;
+
+			Constant c;
+			if (TypeManager.IsEnumType (target_type)) {
+				c = TryReduce (ec, EnumSpec.GetUnderlyingType (target_type));
+				if (c == null)
+					return null;
+
+				return new EnumConstant (c, target_type).Resolve (ec);
+			}
+
+			c = ConvertExplicitly (ec.ConstantCheckState, target_type);
+			if (c != null)
+				c = c.Resolve (ec);
+
+			return c;
+		}
+
+		/// <summary>
+		/// Need to pass type as the constant can require a boxing
+		/// and in such case no optimization is possible
+		/// </summary>
+		public bool IsDefaultInitializer (TypeSpec type)
+		{
+			if (type == Type)
+				return IsDefaultValue;
+
+			return this is NullLiteral;
+		}
+
+		public abstract bool IsDefaultValue {
+			get;
+		}
+
+		public abstract bool IsNegative {
+			get;
+		}
+
+		//
+		// When constant is declared as literal
+		//
+		public virtual bool IsLiteral {
+			get { return false; }
+		}
+		
+		public virtual bool IsOneInteger {
+			get { return false; }
+		}		
+
+		//
+		// Returns true iff 1) the stack type of this is one of Object, 
+		// int32, int64 and 2) this == 0 or this == null.
+		//
+		public virtual bool IsZeroInteger {
+			get { return false; }
+		}
+
+		public override void EmitSideEffect (EmitContext ec)
+		{
+			// do nothing
+		}
+
+		protected override void CloneTo (CloneContext clonectx, Expression target)
+		{
+			// CloneTo: Nothing, we do not keep any state on this expression
+		}
+
+		public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
+		{
+			return System.Linq.Expressions.Expression.Constant (GetTypedValue (), type.GetMetaInfo ());
+		}
+
+		public new Constant Resolve (ResolveContext rc)
+		{
+			if (eclass != ExprClass.Unresolved)
+				return this;
+
+			// Resolved constant has to be still a constant
+			Constant c = (Constant) DoResolve (rc);
+			if (c == null)
+				return null;
+
+			if ((c.eclass & ExprClass.Value) == 0) {
+				c.Error_UnexpectedKind (rc, ResolveFlags.VariableOrValue, loc);
+				return null;
+			}
+
+			if (c.type == null)
+				throw new InternalErrorException ("Expression `{0}' did not set its type after Resolve", c.GetType ());
+
+			return c;
+		}
+	}
+
+	public abstract class IntegralConstant : Constant {
+		protected IntegralConstant (Location loc) :
+			base (loc)
+		{
+		}
+
+		public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
+		{
+			try {
+				ConvertExplicitly (true, target);
+				base.Error_ValueCannotBeConverted (ec, loc, target, expl);
+			}
+			catch
+			{
+				ec.Report.Error (31, loc, "Constant value `{0}' cannot be converted to a `{1}'",
+					GetValue ().ToString (), TypeManager.CSharpName (target));
+			}
+		}
+		
+		public abstract Constant Increment ();
+	}
+	
+	public class BoolConstant : Constant {
+		public readonly bool Value;
+		
+		public BoolConstant (bool val, Location loc):
+			base (loc)
+		{
+			Value = val;
+		}
+
+		override public string AsString ()
+		{
+			return Value ? "true" : "false";
+		}
+
+		protected override Expression DoResolve (ResolveContext ec)
+		{
+			type = TypeManager.bool_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override object GetValue ()
+		{
+			return (object) Value;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write (Value);
+		}
+		
+		public override void Emit (EmitContext ec)
+		{
+			if (Value)
+				ec.Emit (OpCodes.Ldc_I4_1);
+			else
+				ec.Emit (OpCodes.Ldc_I4_0);
+		}
+
+		public override bool IsDefaultValue {
+			get {
+				return !Value;
+			}
+		}
+
+		public override bool IsNegative {
+			get {
+				return false;
+			}
+		}
+	
+		public override bool IsZeroInteger {
+			get { return Value == false; }
+		}
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			return null;
+		}
+
+	}
+
+	public class ByteConstant : IntegralConstant {
+		public readonly byte Value;
+
+		public ByteConstant (byte v, Location loc):
+			base (loc)
+		{
+			Value = v;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write (Value);
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			ec.EmitInt (Value);
+		}
+
+		public override string AsString ()
+		{
+			return Value.ToString ();
+		}
+
+		protected override Expression DoResolve (ResolveContext ec)
+		{
+			type = TypeManager.byte_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override object GetValue ()
+		{
+			return Value;
+		}
+
+		public override Constant Increment ()
+		{
+			return new ByteConstant (checked ((byte)(Value + 1)), loc);
+		}
+
+		public override bool IsDefaultValue {
+			get {
+				return Value == 0;
+			}
+		}
+
+		public override bool IsOneInteger {
+			get {
+				return Value == 1;
+			}
+		}		
+
+		public override bool IsNegative {
+			get {
+				return false;
+			}
+		}
+
+		public override bool IsZeroInteger {
+			get { return Value == 0; }
+		}
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.sbyte_type) {
+				if (in_checked_context){
+					if (Value > SByte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new SByteConstant ((sbyte) Value, Location);
+			}
+			if (target_type == TypeManager.short_type)
+				return new ShortConstant ((short) Value, Location);
+			if (target_type == TypeManager.ushort_type)
+				return new UShortConstant ((ushort) Value, Location);
+			if (target_type == TypeManager.int32_type)
+				return new IntConstant ((int) Value, Location);
+			if (target_type == TypeManager.uint32_type)
+				return new UIntConstant ((uint) Value, Location);
+			if (target_type == TypeManager.int64_type)
+				return new LongConstant ((long) Value, Location);
+			if (target_type == TypeManager.uint64_type)
+				return new ULongConstant ((ulong) Value, Location);
+			if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float) Value, Location);
+			if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double) Value, Location);
+			if (target_type == TypeManager.char_type)
+				return new CharConstant ((char) Value, Location);
+			if (target_type == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) Value, Location);
+
+			return null;
+		}
+
+	}
+
+	public class CharConstant : Constant {
+		public readonly char Value;
+
+		public CharConstant (char v, Location loc):
+			base (loc)
+		{
+			Value = v;
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			type = TypeManager.char_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write ((ushort) Value);
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			ec.EmitInt (Value);
+		}
+
+		static string descape (char c)
+		{
+			switch (c){
+			case '\a':
+				return "\\a"; 
+			case '\b':
+				return "\\b"; 
+			case '\n':
+				return "\\n"; 
+			case '\t':
+				return "\\t"; 
+			case '\v':
+				return "\\v"; 
+			case '\r':
+				return "\\r"; 
+			case '\\':
+				return "\\\\";
+			case '\f':
+				return "\\f"; 
+			case '\0':
+				return "\\0"; 
+			case '"':
+				return "\\\""; 
+			case '\'':
+				return "\\\'"; 
+			}
+			return c.ToString ();
+		}
+
+		public override string AsString ()
+		{
+			return "\"" + descape (Value) + "\"";
+		}
+
+		public override object GetValue ()
+		{
+			return Value;
+		}
+
+		public override bool IsDefaultValue {
+			get {
+				return Value == 0;
+			}
+		}
+
+		public override bool IsNegative {
+			get {
+				return false;
+			}
+		}
+
+		public override bool IsZeroInteger {
+			get { return Value == '\0'; }
+		}
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.byte_type) {
+				if (in_checked_context){
+					if (Value < Byte.MinValue || Value > Byte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new ByteConstant ((byte) Value, Location);
+			}
+			if (target_type == TypeManager.sbyte_type) {
+				if (in_checked_context){
+					if (Value > SByte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new SByteConstant ((sbyte) Value, Location);
+			}
+			if (target_type == TypeManager.short_type) {
+				if (in_checked_context){
+					if (Value > Int16.MaxValue)
+						throw new OverflowException ();
+				}					
+				return new ShortConstant ((short) Value, Location);
+			}
+			if (target_type == TypeManager.int32_type)
+				return new IntConstant ((int) Value, Location);
+			if (target_type == TypeManager.uint32_type)
+				return new UIntConstant ((uint) Value, Location);
+			if (target_type == TypeManager.int64_type)
+				return new LongConstant ((long) Value, Location);
+			if (target_type == TypeManager.uint64_type)
+				return new ULongConstant ((ulong) Value, Location);
+			if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float) Value, Location);
+			if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double) Value, Location);
+			if (target_type == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) Value, Location);
+
+			return null;
+		}
+
+	}
+
+	public class SByteConstant : IntegralConstant {
+		public readonly sbyte Value;
+
+		public SByteConstant (sbyte v, Location loc):
+			base (loc)
+		{
+			Value = v;
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			type = TypeManager.sbyte_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write (Value);
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			ec.EmitInt (Value);
+		}
+
+		public override string AsString ()
+		{
+			return Value.ToString ();
+		}
+
+		public override object GetValue ()
+		{
+			return Value;
+		}
+
+		public override Constant Increment ()
+		{
+		    return new SByteConstant (checked((sbyte)(Value + 1)), loc);
+		}
+
+		public override bool IsDefaultValue {
+			get {
+				return Value == 0;
+			}
+		}
+
+		public override bool IsNegative {
+			get {
+				return Value < 0;
+			}
+		}
+		
+		public override bool IsOneInteger {
+			get {
+				return Value == 1;
+			}
+		}		
+		
+		public override bool IsZeroInteger {
+			get { return Value == 0; }
+		}
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.byte_type) {
+				if (in_checked_context && Value < 0)
+					throw new OverflowException ();
+				return new ByteConstant ((byte) Value, Location);
+			}
+			if (target_type == TypeManager.short_type)
+				return new ShortConstant ((short) Value, Location);
+			if (target_type == TypeManager.ushort_type) {
+				if (in_checked_context && Value < 0)
+					throw new OverflowException ();
+				return new UShortConstant ((ushort) Value, Location);
+			} if (target_type == TypeManager.int32_type)
+				  return new IntConstant ((int) Value, Location);
+			if (target_type == TypeManager.uint32_type) {
+				if (in_checked_context && Value < 0)
+					throw new OverflowException ();
+				return new UIntConstant ((uint) Value, Location);
+			} if (target_type == TypeManager.int64_type)
+				  return new LongConstant ((long) Value, Location);
+			if (target_type == TypeManager.uint64_type) {
+				if (in_checked_context && Value < 0)
+					throw new OverflowException ();
+				return new ULongConstant ((ulong) Value, Location);
+			}
+			if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float) Value, Location);
+			if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double) Value, Location);
+			if (target_type == TypeManager.char_type) {
+				if (in_checked_context && Value < 0)
+					throw new OverflowException ();
+				return new CharConstant ((char) Value, Location);
+			}
+			if (target_type == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) Value, Location);
+
+			return null;
+		}
+
+	}
+
+	public class ShortConstant : IntegralConstant {
+		public readonly short Value;
+
+		public ShortConstant (short v, Location loc):
+			base (loc)
+		{
+			Value = v;
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			type = TypeManager.short_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write (Value);
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			ec.EmitInt (Value);
+		}
+
+		public override string AsString ()
+		{
+			return Value.ToString ();
+		}
+
+		public override object GetValue ()
+		{
+			return Value;
+		}
+
+		public override Constant Increment ()
+		{
+			return new ShortConstant (checked((short)(Value + 1)), loc);
+		}
+
+		public override bool IsDefaultValue {
+			get {
+				return Value == 0;
+			}
+		}
+		
+		public override bool IsZeroInteger {
+			get { return Value == 0; }
+		}
+
+		public override bool IsNegative {
+			get {
+				return Value < 0;
+			}
+		}
+		
+		public override bool IsOneInteger {
+			get {
+				return Value == 1;
+			}
+		}		
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.byte_type) {
+				if (in_checked_context){
+					if (Value < Byte.MinValue || Value > Byte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new ByteConstant ((byte) Value, Location);
+			}
+			if (target_type == TypeManager.sbyte_type) {
+				if (in_checked_context){
+					if (Value < SByte.MinValue || Value > SByte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new SByteConstant ((sbyte) Value, Location);
+			}
+			if (target_type == TypeManager.ushort_type) {
+				if (in_checked_context && Value < 0)
+					throw new OverflowException ();
+				
+				return new UShortConstant ((ushort) Value, Location);
+			}
+			if (target_type == TypeManager.int32_type)
+				return new IntConstant ((int) Value, Location);
+			if (target_type == TypeManager.uint32_type) {
+				if (in_checked_context && Value < 0)
+					throw new OverflowException ();
+				return new UIntConstant ((uint) Value, Location);
+			}
+			if (target_type == TypeManager.int64_type)
+				return new LongConstant ((long) Value, Location);
+			if (target_type == TypeManager.uint64_type) {
+				if (in_checked_context && Value < 0)
+					throw new OverflowException ();
+				return new ULongConstant ((ulong) Value, Location);
+			}
+			if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float) Value, Location);
+			if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double) Value, Location);
+			if (target_type == TypeManager.char_type) {
+				if (in_checked_context){
+					if (Value < Char.MinValue)
+						throw new OverflowException ();
+				}
+				return new CharConstant ((char) Value, Location);
+			}
+			if (target_type == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) Value, Location);
+
+			return null;
+		}
+
+	}
+
+	public class UShortConstant : IntegralConstant {
+		public readonly ushort Value;
+
+		public UShortConstant (ushort v, Location loc):
+			base (loc)
+		{
+			Value = v;
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			type = TypeManager.ushort_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write (Value);
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			ec.EmitInt (Value);
+		}
+
+		public override string AsString ()
+		{
+			return Value.ToString ();
+		}
+
+		public override object GetValue ()
+		{
+			return Value;
+		}
+	
+		public override Constant Increment ()
+		{
+			return new UShortConstant (checked((ushort)(Value + 1)), loc);
+		}
+
+		public override bool IsDefaultValue {
+			get {
+				return Value == 0;
+			}
+		}
+
+		public override bool IsNegative {
+			get {
+				return false;
+			}
+		}
+		
+		public override bool IsOneInteger {
+			get {
+				return Value == 1;
+			}
+		}		
+	
+		public override bool IsZeroInteger {
+			get { return Value == 0; }
+		}
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.byte_type) {
+				if (in_checked_context){
+					if (Value > Byte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new ByteConstant ((byte) Value, Location);
+			}
+			if (target_type == TypeManager.sbyte_type) {
+				if (in_checked_context){
+					if (Value > SByte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new SByteConstant ((sbyte) Value, Location);
+			}
+			if (target_type == TypeManager.short_type) {
+				if (in_checked_context){
+					if (Value > Int16.MaxValue)
+						throw new OverflowException ();
+				}
+				return new ShortConstant ((short) Value, Location);
+			}
+			if (target_type == TypeManager.int32_type)
+				return new IntConstant ((int) Value, Location);
+			if (target_type == TypeManager.uint32_type)
+				return new UIntConstant ((uint) Value, Location);
+			if (target_type == TypeManager.int64_type)
+				return new LongConstant ((long) Value, Location);
+			if (target_type == TypeManager.uint64_type)
+				return new ULongConstant ((ulong) Value, Location);
+			if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float) Value, Location);
+			if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double) Value, Location);
+			if (target_type == TypeManager.char_type) {
+				if (in_checked_context){
+					if (Value > Char.MaxValue)
+						throw new OverflowException ();
+				}
+				return new CharConstant ((char) Value, Location);
+			}
+			if (target_type == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) Value, Location);
+
+			return null;
+		}
+	}
+
+	public class IntConstant : IntegralConstant {
+		public readonly int Value;
+
+		public IntConstant (int v, Location loc):
+			base (loc)
+		{
+			Value = v;
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			type = TypeManager.int32_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write (Value);
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			ec.EmitInt (Value);
+		}
+
+		public override string AsString ()
+		{
+			return Value.ToString ();
+		}
+
+		public override object GetValue ()
+		{
+			return Value;
+		}
+
+		public override Constant Increment ()
+		{
+			return new IntConstant (checked(Value + 1), loc);
+		}
+
+		public override bool IsDefaultValue {
+			get {
+				return Value == 0;
+			}
+		}
+		
+		public override bool IsNegative {
+			get {
+				return Value < 0;
+			}
+		}
+		
+		public override bool IsOneInteger {
+			get {
+				return Value == 1;
+			}
+		}		
+
+		public override bool IsZeroInteger {
+			get { return Value == 0; }
+		}
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.byte_type) {
+				if (in_checked_context){
+					if (Value < Byte.MinValue || Value > Byte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new ByteConstant ((byte) Value, Location);
+			}
+			if (target_type == TypeManager.sbyte_type) {
+				if (in_checked_context){
+					if (Value < SByte.MinValue || Value > SByte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new SByteConstant ((sbyte) Value, Location);
+			}
+			if (target_type == TypeManager.short_type) {
+				if (in_checked_context){
+					if (Value < Int16.MinValue || Value > Int16.MaxValue)
+						throw new OverflowException ();
+				}
+				return new ShortConstant ((short) Value, Location);
+			}
+			if (target_type == TypeManager.ushort_type) {
+				if (in_checked_context){
+					if (Value < UInt16.MinValue || Value > UInt16.MaxValue)
+						throw new OverflowException ();
+				}
+				return new UShortConstant ((ushort) Value, Location);
+			}
+			if (target_type == TypeManager.uint32_type) {
+				if (in_checked_context){
+					if (Value < UInt32.MinValue)
+						throw new OverflowException ();
+				}
+				return new UIntConstant ((uint) Value, Location);
+			}
+			if (target_type == TypeManager.int64_type)
+				return new LongConstant ((long) Value, Location);
+			if (target_type == TypeManager.uint64_type) {
+				if (in_checked_context && Value < 0)
+					throw new OverflowException ();
+				return new ULongConstant ((ulong) Value, Location);
+			}
+			if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float) Value, Location);
+			if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double) Value, Location);
+			if (target_type == TypeManager.char_type) {
+				if (in_checked_context){
+					if (Value < Char.MinValue || Value > Char.MaxValue)
+						throw new OverflowException ();
+				}
+				return new CharConstant ((char) Value, Location);
+			}
+			if (target_type == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) Value, Location);
+
+			return null;
+		}
+
+		public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec type)
+		{
+			if (this.type == type)
+				return this;
+
+			Constant c = TryImplicitIntConversion (type);
+			if (c != null)
+				return c.Resolve (rc);
+
+			return base.ConvertImplicitly (rc, type);
+		}
+
+		/// <summary>
+		///   Attempts to perform an implicit constant conversion of the IntConstant
+		///   into a different data type using casts (See Implicit Constant
+		///   Expression Conversions)
+		/// </summary>
+		Constant TryImplicitIntConversion (TypeSpec target_type)
+		{
+			if (target_type == TypeManager.sbyte_type) {
+				if (Value >= SByte.MinValue && Value <= SByte.MaxValue)
+					return new SByteConstant ((sbyte) Value, loc);
+			} 
+			else if (target_type == TypeManager.byte_type) {
+				if (Value >= Byte.MinValue && Value <= Byte.MaxValue)
+					return new ByteConstant ((byte) Value, loc);
+			} 
+			else if (target_type == TypeManager.short_type) {
+				if (Value >= Int16.MinValue && Value <= Int16.MaxValue)
+					return new ShortConstant ((short) Value, loc);
+			} 
+			else if (target_type == TypeManager.ushort_type) {
+				if (Value >= UInt16.MinValue && Value <= UInt16.MaxValue)
+					return new UShortConstant ((ushort) Value, loc);
+			} 
+			else if (target_type == TypeManager.uint32_type) {
+				if (Value >= 0)
+					return new UIntConstant ((uint) Value, loc);
+			} 
+			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 ULongConstant ((ulong) Value, loc);
+			} 
+			else if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double) Value, loc);
+			else if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float) Value, loc);
+
+			return null;
+		}
+	}
+
+	public class UIntConstant : IntegralConstant {
+		public readonly uint Value;
+
+		public UIntConstant (uint v, Location loc):
+			base (loc)
+		{
+			Value = v;
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			type = TypeManager.uint32_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write (Value);
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			ec.EmitInt (unchecked ((int) Value));
+		}
+
+		public override string AsString ()
+		{
+			return Value.ToString ();
+		}
+
+		public override object GetValue ()
+		{
+			return Value;
+		}
+
+		public override Constant Increment ()
+		{
+			return new UIntConstant (checked(Value + 1), loc);
+		}
+	
+		public override bool IsDefaultValue {
+			get {
+				return Value == 0;
+			}
+		}
+
+		public override bool IsNegative {
+			get {
+				return false;
+			}
+		}
+		
+		public override bool IsOneInteger {
+			get {
+				return Value == 1;
+			}
+		}		
+
+		public override bool IsZeroInteger {
+			get { return Value == 0; }
+		}
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.byte_type) {
+				if (in_checked_context){
+					if (Value < Char.MinValue || Value > Char.MaxValue)
+						throw new OverflowException ();
+				}
+				return new ByteConstant ((byte) Value, Location);
+			}
+			if (target_type == TypeManager.sbyte_type) {
+				if (in_checked_context){
+					if (Value > SByte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new SByteConstant ((sbyte) Value, Location);
+			}
+			if (target_type == TypeManager.short_type) {
+				if (in_checked_context){
+					if (Value > Int16.MaxValue)
+						throw new OverflowException ();
+				}
+				return new ShortConstant ((short) Value, Location);
+			}
+			if (target_type == TypeManager.ushort_type) {
+				if (in_checked_context){
+					if (Value < UInt16.MinValue || Value > UInt16.MaxValue)
+						throw new OverflowException ();
+				}
+				return new UShortConstant ((ushort) Value, Location);
+			}
+			if (target_type == TypeManager.int32_type) {
+				if (in_checked_context){
+					if (Value > Int32.MaxValue)
+						throw new OverflowException ();
+				}
+				return new IntConstant ((int) Value, Location);
+			}
+			if (target_type == TypeManager.int64_type)
+				return new LongConstant ((long) Value, Location);
+			if (target_type == TypeManager.uint64_type)
+				return new ULongConstant ((ulong) Value, Location);
+			if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float) Value, Location);
+			if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double) Value, Location);
+			if (target_type == TypeManager.char_type) {
+				if (in_checked_context){
+					if (Value < Char.MinValue || Value > Char.MaxValue)
+						throw new OverflowException ();
+				}
+				return new CharConstant ((char) Value, Location);
+			}
+			if (target_type == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) Value, Location);
+
+			return null;
+		}
+
+	}
+
+	public class LongConstant : IntegralConstant {
+		public readonly long Value;
+
+		public LongConstant (long v, Location loc):
+			base (loc)
+		{
+			Value = v;
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			type = TypeManager.int64_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write (Value);
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			ec.EmitLong (Value);
+		}
+
+		public override string AsString ()
+		{
+			return Value.ToString ();
+		}
+
+		public override object GetValue ()
+		{
+			return Value;
+		}
+
+		public override Constant Increment ()
+		{
+			return new LongConstant (checked(Value + 1), loc);
+		}
+		
+		public override bool IsDefaultValue {
+			get {
+				return Value == 0;
+			}
+		}
+
+		public override bool IsNegative {
+			get {
+				return Value < 0;
+			}
+		}
+		
+		public override bool IsOneInteger {
+			get {
+				return Value == 1;
+			}
+		}		
+
+		public override bool IsZeroInteger {
+			get { return Value == 0; }
+		}
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.byte_type) {
+				if (in_checked_context){
+					if (Value < Byte.MinValue || Value > Byte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new ByteConstant ((byte) Value, Location);
+			}
+			if (target_type == TypeManager.sbyte_type) {
+				if (in_checked_context){
+					if (Value < SByte.MinValue || Value > SByte.MaxValue)
+						throw new OverflowException ();
+				}
+				return new SByteConstant ((sbyte) Value, Location);
+			}
+			if (target_type == TypeManager.short_type) {
+				if (in_checked_context){
+					if (Value < Int16.MinValue || Value > Int16.MaxValue)
+						throw new OverflowException ();
+				}
+				return new ShortConstant ((short) Value, Location);
+			}
+			if (target_type == TypeManager.ushort_type) {
+				if (in_checked_context){
+					if (Value < UInt16.MinValue || Value > UInt16.MaxValue)
+						throw new OverflowException ();
+				}
+				return new UShortConstant ((ushort) Value, Location);
+			}
+			if (target_type == TypeManager.int32_type) {
+				if (in_checked_context){
+					if (Value < Int32.MinValue || Value > Int32.MaxValue)
+						throw new OverflowException ();
+				}
+				return new IntConstant ((int) Value, Location);
+			}
+			if (target_type == TypeManager.uint32_type) {
+				if (in_checked_context){
+					if (Value < UInt32.MinValue || Value > UInt32.MaxValue)
+						throw new OverflowException ();
+				}
+				return new UIntConstant ((uint) Value, Location);
+			}
+			if (target_type == TypeManager.uint64_type) {
+				if (in_checked_context && Value < 0)
+					throw new OverflowException ();
+				return new ULongConstant ((ulong) Value, Location);
+			}
+			if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float) Value, Location);
+			if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double) Value, Location);
+			if (target_type == TypeManager.char_type) {
+				if (in_checked_context){
+					if (Value < Char.MinValue || Value > Char.MaxValue)
+						throw new OverflowException ();
+				}
+				return new CharConstant ((char) Value, Location);
+			}
+			if (target_type == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) Value, Location);
+
+			return null;
+		}
+
+		public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec type)
+		{
+			if (Value >= 0 && type == TypeManager.uint64_type) {
+				return new ULongConstant ((ulong) Value, loc).Resolve (rc);
+			}
+
+			return base.ConvertImplicitly (rc, type);
+		}
+	}
+
+	public class ULongConstant : IntegralConstant {
+		public readonly ulong Value;
+
+		public ULongConstant (ulong v, Location loc):
+			base (loc)
+		{
+			Value = v;
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			type = TypeManager.uint64_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write (Value);
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			ec.EmitLong (unchecked ((long) Value));
+		}
+
+		public override string AsString ()
+		{
+			return Value.ToString ();
+		}
+
+		public override object GetValue ()
+		{
+			return Value;
+		}
+
+		public override Constant Increment ()
+		{
+			return new ULongConstant (checked(Value + 1), loc);
+		}
+
+		public override bool IsDefaultValue {
+			get {
+				return Value == 0;
+			}
+		}
+
+		public override bool IsNegative {
+			get {
+				return false;
+			}
+		}
+		
+		public override bool IsOneInteger {
+			get {
+				return Value == 1;
+			}
+		}		
+
+		public override bool IsZeroInteger {
+			get { return Value == 0; }
+		}
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.byte_type) {
+				if (in_checked_context && Value > Byte.MaxValue)
+					throw new OverflowException ();
+				return new ByteConstant ((byte) Value, Location);
+			}
+			if (target_type == TypeManager.sbyte_type) {
+				if (in_checked_context && Value > ((ulong) SByte.MaxValue))
+					throw new OverflowException ();
+				return new SByteConstant ((sbyte) Value, Location);
+			}
+			if (target_type == TypeManager.short_type) {
+				if (in_checked_context && Value > ((ulong) Int16.MaxValue))
+					throw new OverflowException ();
+				return new ShortConstant ((short) Value, Location);
+			}
+			if (target_type == TypeManager.ushort_type) {
+				if (in_checked_context && Value > UInt16.MaxValue)
+					throw new OverflowException ();
+				return new UShortConstant ((ushort) Value, Location);
+			}
+			if (target_type == TypeManager.int32_type) {
+				if (in_checked_context && Value > UInt32.MaxValue)
+					throw new OverflowException ();
+				return new IntConstant ((int) Value, Location);
+			}
+			if (target_type == TypeManager.uint32_type) {
+				if  (in_checked_context && Value > UInt32.MaxValue)
+					throw new OverflowException ();
+				return new UIntConstant ((uint) Value, Location);
+			}
+			if (target_type == TypeManager.int64_type) {
+				if (in_checked_context && Value > Int64.MaxValue)
+					throw new OverflowException ();
+				return new LongConstant ((long) Value, Location);
+			}
+			if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float) Value, Location);
+			if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double) Value, Location);
+			if (target_type == TypeManager.char_type) {
+				if (in_checked_context && Value > Char.MaxValue)
+					throw new OverflowException ();
+				return new CharConstant ((char) Value, Location);
+			}
+			if (target_type == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) Value, Location);
 
-	using System;
-	using System.Reflection;
-	using System.Reflection.Emit;
-	using System.Collections;
+			return null;
+		}
 
+	}
 
-	public class Constant : Expression {
+	public class FloatConstant : Constant {
+		public float Value;
 
-		public readonly string     Name;
-		public readonly string     ConstantType;
-		public Expression Expr;
-		public Attributes  OptAttributes;
-		
-		int mod_flags;
-		Location Location;
-		public FieldBuilder FieldBuilder;
+		public FloatConstant (float v, Location loc):
+			base (loc)
+		{
+			Value = v;
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			type = TypeManager.float_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write (Value);
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			ec.Emit (OpCodes.Ldc_R4, Value);
+		}
 
-		public const int AllowedModifiers =
-			Modifiers.NEW |
-			Modifiers.PUBLIC |
-			Modifiers.PROTECTED |
-			Modifiers.INTERNAL |
-			Modifiers.PRIVATE;
+		public override string AsString ()
+		{
+			return Value.ToString ();
+		}
 
-		public Constant (string constant_type, string name, Expression expr, int mod_flags,
-				 Attributes attrs, Location loc)
+		public override object GetValue ()
 		{
-			this.ConstantType = constant_type;
-			this.Name = name;
-			this.Expr = expr;
-			this.mod_flags = Modifiers.Check (AllowedModifiers, mod_flags, Modifiers.PRIVATE);
-			this.Location = loc;
-			OptAttributes = attrs;
+			return Value;
 		}
 
-		public FieldAttributes FieldAttr {
+		public override bool IsDefaultValue {
 			get {
-				return FieldAttributes.Literal | FieldAttributes.Static |
-					Modifiers.FieldAttr (mod_flags) ;
+				return Value == 0;
 			}
 		}
 
-		public int ModFlags {
+		public override bool IsNegative {
 			get {
-				return mod_flags;
+				return Value < 0;
+			}
+		}
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.byte_type) {
+				if (in_checked_context){
+					if (Value < byte.MinValue || Value > byte.MaxValue || float.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new ByteConstant ((byte) Value, Location);
+			}
+			if (target_type == TypeManager.sbyte_type) {
+				if (in_checked_context){
+					if (Value < sbyte.MinValue || Value > sbyte.MaxValue || float.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new SByteConstant ((sbyte) Value, Location);
+			}
+			if (target_type == TypeManager.short_type) {
+				if (in_checked_context){
+					if (Value < short.MinValue || Value > short.MaxValue || float.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new ShortConstant ((short) Value, Location);
+			}
+			if (target_type == TypeManager.ushort_type) {
+				if (in_checked_context){
+					if (Value < ushort.MinValue || Value > ushort.MaxValue || float.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new UShortConstant ((ushort) Value, Location);
+			}
+			if (target_type == TypeManager.int32_type) {
+				if (in_checked_context){
+					if (Value < int.MinValue || Value > int.MaxValue || float.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new IntConstant ((int) Value, Location);
+			}
+			if (target_type == TypeManager.uint32_type) {
+				if (in_checked_context){
+					if (Value < uint.MinValue || Value > uint.MaxValue || float.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new UIntConstant ((uint) Value, Location);
 			}
+			if (target_type == TypeManager.int64_type) {
+				if (in_checked_context){
+					if (Value < long.MinValue || Value > long.MaxValue || float.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new LongConstant ((long) Value, Location);
+			}
+			if (target_type == TypeManager.uint64_type) {
+				if (in_checked_context){
+					if (Value < ulong.MinValue || Value > ulong.MaxValue || float.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new ULongConstant ((ulong) Value, Location);
+			}
+			if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double) Value, Location);
+			if (target_type == TypeManager.char_type) {
+				if (in_checked_context){
+					if (Value < (float) char.MinValue || Value > (float) char.MaxValue || float.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new CharConstant ((char) Value, Location);
+			}
+			if (target_type == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) Value, Location);
+
+			return null;
+		}
+
+	}
+
+	public class DoubleConstant : Constant {
+		public double Value;
+
+		public DoubleConstant (double v, Location loc):
+			base (loc)
+		{
+			Value = v;
 		}
 
-		public override Expression DoResolve (EmitContext ec)
+		protected override Expression DoResolve (ResolveContext rc)
 		{
-			// FIXME: implement
+			type = TypeManager.double_type;
+			eclass = ExprClass.Value;
 			return this;
 		}
 
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			enc.Stream.Write (Value);
+		}
+
 		public override void Emit (EmitContext ec)
 		{
-			throw new Exception ("Unimplemented");
+			ec.Emit (OpCodes.Ldc_R8, Value);
 		}
 
-		void WarningNotHiding (TypeContainer parent)
+		public override string AsString ()
 		{
-			Report.Warning (
-				109, Location,
-				"The member `" + parent.Name + "." + Name + "' does not hide an " +
-				"inherited member.  The keyword new is not required");
+			return Value.ToString ();
 		}
-		
-		/// <summary>
-		///   Defines the constant in the @parent
-		/// </summary>
-		public void Define (TypeContainer parent)
+
+		public override object GetValue ()
 		{
-			type = parent.LookupType (ConstantType, true);
+			return Value;
+		}
 
-			if (type == null)
-				return;
-			
-			if (!TypeManager.IsBuiltinType (type) && (!type.IsSubclassOf (TypeManager.enum_type))) {
-				Report.Error (-3, Location, "Constant type is not valid (only system types are allowed)");
-				return;
+		public override bool IsDefaultValue {
+			get {
+				return Value == 0;
 			}
+		}
 
-			Type ptype = parent.TypeBuilder.BaseType;
+		public override bool IsNegative {
+			get {
+				return Value < 0;
+			}
+		}
 
-			if (ptype != null) {
-				MemberInfo [] mi = TypeContainer.FindMembers (ptype, MemberTypes.Field, BindingFlags.Public,
-									   Type.FilterName, Name);
-				
-				if (mi == null || mi.Length == 0)
-					if ((ModFlags & Modifiers.NEW) != 0)
-						WarningNotHiding (parent);
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.byte_type) {
+				if (in_checked_context){
+					if (Value < Byte.MinValue || Value > Byte.MaxValue || double.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new ByteConstant ((byte) Value, Location);
+			}
+			if (target_type == TypeManager.sbyte_type) {
+				if (in_checked_context){
+					if (Value < SByte.MinValue || Value > SByte.MaxValue || double.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new SByteConstant ((sbyte) Value, Location);
+			}
+			if (target_type == TypeManager.short_type) {
+				if (in_checked_context){
+					if (Value < short.MinValue || Value > short.MaxValue || double.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new ShortConstant ((short) Value, Location);
+			}
+			if (target_type == TypeManager.ushort_type) {
+				if (in_checked_context){
+					if (Value < ushort.MinValue || Value > ushort.MaxValue || double.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new UShortConstant ((ushort) Value, Location);
+			}
+			if (target_type == TypeManager.int32_type) {
+				if (in_checked_context){
+					if (Value < int.MinValue || Value > int.MaxValue || double.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new IntConstant ((int) Value, Location);
+			}
+			if (target_type == TypeManager.uint32_type) {
+				if (in_checked_context){
+					if (Value < uint.MinValue || Value > uint.MaxValue || double.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new UIntConstant ((uint) Value, Location);
+			}
+			if (target_type == TypeManager.int64_type) {
+				if (in_checked_context){
+					if (Value < long.MinValue || Value > long.MaxValue || double.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new LongConstant ((long) Value, Location);
+			}
+			if (target_type == TypeManager.uint64_type) {
+				if (in_checked_context){
+					if (Value < ulong.MinValue || Value > ulong.MaxValue || double.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new ULongConstant ((ulong) Value, Location);
+			}
+			if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float) Value, Location);
+			if (target_type == TypeManager.char_type) {
+				if (in_checked_context){
+					if (Value < (double) char.MinValue || Value > (double) char.MaxValue || double.IsNaN (Value))
+						throw new OverflowException ();
+				}
+				return new CharConstant ((char) Value, Location);
+			}
+			if (target_type == TypeManager.decimal_type)
+				return new DecimalConstant ((decimal) Value, Location);
+
+			return null;
+		}
+
+	}
+
+	public class DecimalConstant : Constant {
+		public readonly decimal Value;
+
+		public DecimalConstant (decimal d, Location loc):
+			base (loc)
+		{
+			Value = d;
+		}
+
+		override public string AsString ()
+		{
+			return Value.ToString () + "M";
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			type = TypeManager.decimal_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override object GetValue ()
+		{
+			return (object) Value;
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			int [] words = decimal.GetBits (Value);
+			int power = (words [3] >> 16) & 0xff;
+
+			if (power == 0) {
+				if (Value <= int.MaxValue && Value >= int.MinValue) {
+					if (TypeManager.void_decimal_ctor_int_arg == null) {
+						TypeManager.void_decimal_ctor_int_arg = TypeManager.GetPredefinedConstructor (
+							TypeManager.decimal_type, loc, TypeManager.int32_type);
+
+						if (TypeManager.void_decimal_ctor_int_arg == null)
+							return;
+					}
+
+					ec.EmitInt ((int) Value);
+					ec.Emit (OpCodes.Newobj, TypeManager.void_decimal_ctor_int_arg);
+					return;
+				}
+
+				if (Value <= long.MaxValue && Value >= long.MinValue) {
+					if (TypeManager.void_decimal_ctor_long_arg == null) {
+						TypeManager.void_decimal_ctor_long_arg = TypeManager.GetPredefinedConstructor (
+							TypeManager.decimal_type, loc, TypeManager.int64_type);
+
+						if (TypeManager.void_decimal_ctor_long_arg == null)
+							return;
+					}
+
+					ec.EmitLong ((long) Value);
+					ec.Emit (OpCodes.Newobj, TypeManager.void_decimal_ctor_long_arg);
+					return;
+				}
+			}
+
+			ec.EmitInt (words [0]);
+			ec.EmitInt (words [1]);
+			ec.EmitInt (words [2]);
+
+			// sign
+			ec.EmitInt (words [3] >> 31);
+
+			// power
+			ec.EmitInt (power);
+
+			if (TypeManager.void_decimal_ctor_five_args == null) {
+				TypeManager.void_decimal_ctor_five_args = TypeManager.GetPredefinedConstructor (
+					TypeManager.decimal_type, loc, TypeManager.int32_type, TypeManager.int32_type,
+					TypeManager.int32_type, TypeManager.bool_type, TypeManager.byte_type);
+
+				if (TypeManager.void_decimal_ctor_five_args == null)
+					return;
+			}
+
+			ec.Emit (OpCodes.Newobj, TypeManager.void_decimal_ctor_five_args);
+		}
+
+		public override bool IsDefaultValue {
+			get {
+				return Value == 0;
+			}
+		}
+
+		public override bool IsNegative {
+			get {
+				return Value < 0;
+			}
+		}
 
-			} else if ((ModFlags & Modifiers.NEW) != 0)
-				WarningNotHiding (parent);
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			if (target_type == TypeManager.sbyte_type)
+				return new SByteConstant ((sbyte)Value, loc);
+			if (target_type == TypeManager.byte_type)
+				return new ByteConstant ((byte)Value, loc);
+			if (target_type == TypeManager.short_type)
+				return new ShortConstant ((short)Value, loc);
+			if (target_type == TypeManager.ushort_type)
+				return new UShortConstant ((ushort)Value, loc);
+			if (target_type == TypeManager.int32_type)
+				return new IntConstant ((int)Value, loc);
+			if (target_type == TypeManager.uint32_type)
+				return new UIntConstant ((uint)Value, loc);
+			if (target_type == TypeManager.int64_type)
+				return new LongConstant ((long)Value, loc);
+			if (target_type == TypeManager.uint64_type)
+				return new ULongConstant ((ulong)Value, loc);
+			if (target_type == TypeManager.char_type)
+				return new CharConstant ((char)Value, loc);
+			if (target_type == TypeManager.float_type)
+				return new FloatConstant ((float)Value, loc);
+			if (target_type == TypeManager.double_type)
+				return new DoubleConstant ((double)Value, loc);
+
+			return null;
+		}
+
+	}
+
+	public class StringConstant : Constant {
+		public readonly string Value;
+
+		public StringConstant (string s, Location loc):
+			base (loc)
+		{
+			Value = s;
+		}
+
+		// FIXME: Escape the string.
+		override public string AsString ()
+		{
+			return "\"" + Value + "\"";
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			type = TypeManager.string_type;
+			eclass = ExprClass.Value;
+			return this;
+		}
 
-			FieldBuilder = parent.TypeBuilder.DefineField (Name, type, FieldAttr);
+		public override object GetValue ()
+		{
+			return Value;
 		}
 		
-		/// <summary>
-		///  Emits the field value by evaluating the expression
-		/// </summary>
-		public void EmitConstant (TypeContainer parent)
+		public override void Emit (EmitContext ec)
 		{
-			if (FieldBuilder == null)
+			if (Value == null) {
+				ec.Emit (OpCodes.Ldnull);
 				return;
-			
-			EmitContext ec = new EmitContext (parent, Location, null, type, ModFlags);
+			}
 
-			Expr = Expression.Reduce (ec, Expr);
+			//
+			// Use string.Empty for both literals and constants even if
+			// it's not allowed at language level
+			//
+			if (Value.Length == 0 && RootContext.Optimize && !TypeManager.IsEqual (ec.CurrentType, TypeManager.string_type)) {
+				if (TypeManager.string_empty == null)
+					TypeManager.string_empty = TypeManager.GetPredefinedField (TypeManager.string_type, "Empty", loc, TypeManager.string_type);
 
-			if (!(Expr is Literal)) {
-				Report.Error (150, Location, "A constant value is expected");
-				return;
+				if (TypeManager.string_empty != null) {
+					ec.Emit (OpCodes.Ldsfld, TypeManager.string_empty);
+					return;
+				}
+			}
+
+			ec.Emit (OpCodes.Ldstr, Value);
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			// cast to object
+			if (type != targetType)
+				enc.Encode (type);
+
+			enc.Encode (Value);
+		}
+
+		public override bool IsDefaultValue {
+			get {
+				return Value == null;
 			}
+		}
 
-			object val = ((Literal) Expr).GetValue ();
+		public override bool IsNegative {
+			get {
+				return false;
+			}
+		}
 
-			FieldBuilder.SetConstant (val);
+		public override bool IsNull {
+			get {
+				return IsDefaultValue;
+			}
+		}
 
-			TypeManager.RegisterField (FieldBuilder, val);
-			
-			return;
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			return null;
 		}
 	}
-}
 
+	//
+	// Null constant can have its own type, think of `default (Foo)'
+	//
+	public class NullConstant : Constant
+	{
+		public NullConstant (TypeSpec type, Location loc)
+			: base (loc)
+		{
+			eclass = ExprClass.Value;
+			this.type = type;
+		}
+
+		public override string AsString ()
+		{
+			return GetSignatureForError ();
+		}
+
+		public override Expression CreateExpressionTree (ResolveContext ec)
+		{
+			if (type == InternalType.Null || type == TypeManager.object_type) {
+				// Optimized version, also avoids referencing literal internal type
+				Arguments args = new Arguments (1);
+				args.Add (new Argument (this));
+				return CreateExpressionFactoryCall (ec, "Constant", args);
+			}
+
+			return base.CreateExpressionTree (ec);
+		}
+
+		protected override Expression DoResolve (ResolveContext ec)
+		{
+			return this;
+		}
+
+		public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+		{
+			// Type it as string cast
+			if (targetType == TypeManager.object_type || targetType == TypeManager.null_type)
+				enc.Encode (TypeManager.string_type);
+
+			var ac = targetType as ArrayContainer;
+			if (ac != null) {
+				if (ac.Rank != 1)
+					base.EncodeAttributeValue (rc, enc, targetType);
+				else
+					enc.Stream.Write (uint.MaxValue);
+			} else {
+				enc.Stream.Write (byte.MaxValue);
+			}
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			ec.Emit (OpCodes.Ldnull);
+
+			// Only to make verifier happy
+			if (TypeManager.IsGenericParameter (type))
+				ec.Emit (OpCodes.Unbox_Any, type);
+		}
+
+		public override string ExprClassName {
+			get {
+				return GetSignatureForError ();
+			}
+		}
+
+		public override string GetSignatureForError ()
+		{
+			return "null";
+		}
+
+		public override Constant ConvertExplicitly (bool inCheckedContext, TypeSpec targetType)
+		{
+			if (targetType.IsPointer) {
+				if (IsLiteral || this is NullPointer)
+					return new EmptyConstantCast (new NullPointer (loc), targetType);
+
+				return null;
+			}
+
+			// Exlude internal compiler types
+			if (targetType == InternalType.AnonymousMethod)
+				return null;
+
+			if (!IsLiteral && !Convert.ImplicitStandardConversionExists (this, targetType))
+				return null;
+
+			if (TypeManager.IsReferenceType (targetType))
+				return new NullConstant (targetType, loc);
+
+			if (TypeManager.IsNullableType (targetType))
+				return Nullable.LiftedNull.Create (targetType, loc);
+
+			return null;
+		}
+
+		public override Constant ConvertImplicitly (ResolveContext rc, TypeSpec targetType)
+		{
+			return ConvertExplicitly (false, targetType);
+		}
+
+		public override object GetValue ()
+		{
+			return null;
+		}
+
+		public override bool IsDefaultValue {
+			get { return true; }
+		}
+
+		public override bool IsNegative {
+			get { return false; }
+		}
+
+		public override bool IsNull {
+			get { return true; }
+		}
+
+		public override bool IsZeroInteger {
+			get { return true; }
+		}
+	}
+
+	/// <summary>
+	///   The value is constant, but when emitted has a side effect.  This is
+	///   used by BitwiseAnd to ensure that the second expression is invoked
+	///   regardless of the value of the left side.  
+	/// </summary>
+	public class SideEffectConstant : Constant {
+		public Constant value;
+		Expression side_effect;
+		
+		public SideEffectConstant (Constant value, Expression side_effect, Location loc) : base (loc)
+		{
+			this.value = value;
+			while (side_effect is SideEffectConstant)
+				side_effect = ((SideEffectConstant) side_effect).side_effect;
+			this.side_effect = side_effect;
+		}
+
+		public override string AsString ()
+		{
+			return value.AsString ();
+		}
+
+		protected override Expression DoResolve (ResolveContext rc)
+		{
+			value = value.Resolve (rc);
+
+			type = value.Type;
+			eclass = ExprClass.Value;
+			return this;
+		}
+
+		public override object GetValue ()
+		{
+			return value.GetValue ();
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			side_effect.EmitSideEffect (ec);
+			value.Emit (ec);
+		}
+
+		public override void EmitSideEffect (EmitContext ec)
+		{
+			side_effect.EmitSideEffect (ec);
+			value.EmitSideEffect (ec);
+		}
+
+		public override bool IsDefaultValue {
+			get { return value.IsDefaultValue; }
+		}
 
+		public override bool IsNegative {
+			get { return value.IsNegative; }
+		}
+
+		public override bool IsZeroInteger {
+			get { return value.IsZeroInteger; }
+		}
+
+		public override Constant ConvertExplicitly (bool in_checked_context, TypeSpec target_type)
+		{
+			Constant new_value = value.ConvertExplicitly (in_checked_context, target_type);
+			return new_value == null ? null : new SideEffectConstant (new_value, side_effect, new_value.Location);
+		}
+	}
+}