mcs/mcs/expression.cs

   1 //
   2 // expression.cs: Expression representation for the IL tree.
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //
   7 // (C) 2001 Ximian, Inc.
   8 //
   9 //
  10 // Ideas:
  11 //   Maybe we should make Resolve be an instance method that just calls
  12 //   the virtual DoResolve function and checks conditions like the eclass
  13 //   and type being set if a non-null value is returned.  For robustness
  14 //   purposes.
  15 //
  16
  17 namespace CIR {
  18         using System.Collections;
  19         using System.Diagnostics;
  20         using System;
  21         using System.Reflection;
  22         using System.Reflection.Emit;
  23         using System.Text;
  24
  25         // <remarks>
  26         //   The ExprClass class contains the is used to pass the
  27         //   classification of an expression (value, variable, namespace,
  28         //   type, method group, property access, event access, indexer access,
  29         //   nothing).
  30         // </remarks>
  31         public enum ExprClass {
  32                 Invalid,
  33
  34                 Value,
  35                 Variable,   // Every Variable should implement LValue
  36                 Namespace,
  37                 Type,
  38                 MethodGroup,
  39                 PropertyAccess,
  40                 EventAccess,
  41                 IndexerAccess,
  42                 Nothing,
  43         }
  44
  45         // <remarks>
  46         //   Base class for expressions
  47         // </remarks>
  48         public abstract class Expression {
  49                 protected ExprClass eclass;
  50                 protected Type      type;
  51
  52                 public Type Type {
  53                         get {
  54                                 return type;
  55                         }
  56
  57                         set {
  58                                 type = value;
  59                         }
  60                 }
  61
  62                 public ExprClass ExprClass {
  63                         get {
  64                                 return eclass;
  65                         }
  66
  67                         set {
  68                                 eclass = value;
  69                         }
  70                 }
  71
  72                 // <summary>
  73                 //   Utility wrapper routine for Error, just to beautify the code
  74                 // </summary>
  75                 static protected void Error (TypeContainer tc, int error, string s)
  76                 {
  77                         tc.RootContext.Report.Error (error, s);
  78                 }
  79
  80                 static protected void Error (TypeContainer tc, int error, Location l, string s)
  81                 {
  82                         tc.RootContext.Report.Error (error, l, s);
  83                 }
  84
  85                 // <summary>
  86                 //   Utility wrapper routine for Warning, just to beautify the code
  87                 // </summary>
  88                 static protected void Warning (TypeContainer tc, int warning, string s)
  89                 {
  90                         tc.RootContext.Report.Warning (warning, s);
  91                 }
  92
  93                 // <summary>
  94                 //   Performs semantic analysis on the Expression
  95                 // </summary>
  96                 //
  97                 // <remarks>
  98                 //   The Resolve method is invoked to perform the semantic analysis
  99                 //   on the node.
 100                 //
 101                 //   The return value is an expression (it can be the
 102                 //   same expression in some cases) or a new
 103                 //   expression that better represents this node.
 104                 //
 105                 //   For example, optimizations of Unary (LiteralInt)
 106                 //   would return a new LiteralInt with a negated
 107                 //   value.
 108                 //
 109                 //   If there is an error during semantic analysis,
 110                 //   then an error should
 111                 //   be reported (using TypeContainer.RootContext.Report) and a null
 112                 //   value should be returned.
 113                 //
 114                 //   There are two side effects expected from calling
 115                 //   Resolve(): the the field variable "eclass" should
 116                 //   be set to any value of the enumeration
 117                 //   `ExprClass' and the type variable should be set
 118                 //   to a valid type (this is the type of the
 119                 //   expression).
 120                 // </remarks>
 121
 122                 public abstract Expression Resolve (TypeContainer tc);
 123
 124                 // <summary>
 125                 //   Emits the code for the expression
 126                 // </summary>
 127                 //
 128                 // <remarks>
 129                 //
 130                 //   The Emit method is invoked to generate the code
 131                 //   for the expression.
 132                 //
 133                 // </remarks>
 134                 public abstract void Emit (EmitContext ec);
 135
 136                 // <summary>
 137                 //   Protected constructor.  Only derivate types should
 138                 //   be able to be created
 139                 // </summary>
 140
 141                 protected Expression ()
 142                 {
 143                         eclass = ExprClass.Invalid;
 144                         type = null;
 145                 }
 146
 147                 //
 148                 // Returns a fully formed expression after a MemberLookup
 149                 //
 150                 static Expression ExprClassFromMemberInfo (MemberInfo mi)
 151                 {
 152                         if (mi is EventInfo){
 153                                 return new EventExpr ((EventInfo) mi);
 154                         } else if (mi is FieldInfo){
 155                                 return new FieldExpr ((FieldInfo) mi);
 156                         } else if (mi is PropertyInfo){
 157                                 return new PropertyExpr ((PropertyInfo) mi);
 158                         } else if (mi is Type)
 159                                 return new TypeExpr ((Type) mi);
 160
 161                         return null;
 162                 }
 163
 164                 //
 165                 // FIXME: Probably implement a cache for (t,name,current_access_set)?
 166                 //
 167                 // FIXME: We need to cope with access permissions here, or this wont
 168                 // work!
 169                 //
 170                 // This code could use some optimizations, but we need to do some
 171                 // measurements.  For example, we could use a delegate to `flag' when
 172                 // something can not any longer be a method-group (because it is something
 173                 // else).
 174                 //
 175                 // Return values:
 176                 //     If the return value is an Array, then it is an array of
 177                 //     MethodBases
 178                 //
 179                 //     If the return value is an MemberInfo, it is anything, but a Method
 180                 //
 181                 //     null on error.
 182                 //
 183                 // FIXME: When calling MemberLookup inside an `Invocation', we should pass
 184                 // the arguments here and have MemberLookup return only the methods that
 185                 // match the argument count/type, unlike we are doing now (we delay this
 186                 // decision).
 187                 //
 188                 // This is so we can catch correctly attempts to invoke instance methods
 189                 // from a static body (scan for error 120 in ResolveSimpleName).
 190                 //
 191                 public static Expression MemberLookup (TypeContainer tc, Type t, string name,
 192                                                        bool same_type, MemberTypes mt, BindingFlags bf)
 193                 {
 194                         if (same_type)
 195                                 bf |= BindingFlags.NonPublic;
 196
 197                         MemberInfo [] mi = tc.RootContext.TypeManager.FindMembers (
 198                                 t, mt, bf, Type.FilterName, name);
 199
 200                         if (mi == null)
 201                                 return null;
 202
 203                         if (mi.Length == 1 && !(mi [0] is MethodBase))
 204                                 return Expression.ExprClassFromMemberInfo (mi [0]);
 205
 206                         for (int i = 0; i < mi.Length; i++)
 207                                 if (!(mi [i] is MethodBase)){
 208                                         Error (tc,
 209                                                -5, "Do not know how to reproduce this case: " +
 210                                                "Methods and non-Method with the same name, " +
 211                                                "report this please");
 212
 213                                         for (i = 0; i < mi.Length; i++){
 214                                                 Type tt = mi [i].GetType ();
 215
 216                                                 Console.WriteLine (i + ": " + mi [i]);
 217                                                 while (tt != TypeManager.object_type){
 218                                                         Console.WriteLine (tt);
 219                                                         tt = tt.BaseType;
 220                                                 }
 221                                         }
 222                                 }
 223
 224                         return new MethodGroupExpr (mi);
 225                 }
 226
 227                 public const MemberTypes AllMemberTypes =
 228                         MemberTypes.Constructor |
 229                         MemberTypes.Event       |
 230                         MemberTypes.Field       |
 231                         MemberTypes.Method      |
 232                         MemberTypes.NestedType  |
 233                         MemberTypes.Property;
 234
 235                 public const BindingFlags AllBindingsFlags =
 236                         BindingFlags.Public |
 237                         BindingFlags.Static |
 238                         BindingFlags.Instance;
 239
 240                 public static Expression MemberLookup (TypeContainer tc, Type t, string name,
 241                                                        bool same_type)
 242                 {
 243                         return MemberLookup (tc, t, name, same_type, AllMemberTypes, AllBindingsFlags);
 244                 }
 245
 246                 //
 247                 // I am in general unhappy with this implementation.
 248                 //
 249                 // I need to revise this.
 250                 //
 251                 static public Expression ResolveMemberAccess (TypeContainer tc, string name)
 252                 {
 253                         Expression left_e = null;
 254                         int dot_pos = name.LastIndexOf (".");
 255                         string left = name.Substring (0, dot_pos);
 256                         string right = name.Substring (dot_pos + 1);
 257                         Type t;
 258
 259                         if ((t = tc.LookupType (left, false)) != null)
 260                                 left_e = new TypeExpr (t);
 261                         else {
 262                                 //
 263                                 // FIXME: IMplement:
 264
 265                                 // Handle here:
 266                                 //    T.P  Static property access (P) on Type T.
 267                                 //    e.P  instance property access on instance e for P.
 268                                 //    p
 269                                 //
 270                         }
 271
 272                         if (left_e == null){
 273                                 Error (tc, 246, "Can not find type or namespace `"+left+"'");
 274                                 return null;
 275                         }
 276
 277                         switch (left_e.ExprClass){
 278                         case ExprClass.Type:
 279                                 return  MemberLookup (tc,
 280                                                       left_e.Type, right,
 281                                                       left_e.Type == tc.TypeBuilder);
 282
 283                         case ExprClass.Namespace:
 284                         case ExprClass.PropertyAccess:
 285                         case ExprClass.IndexerAccess:
 286                         case ExprClass.Variable:
 287                         case ExprClass.Value:
 288                         case ExprClass.Nothing:
 289                         case ExprClass.EventAccess:
 290                         case ExprClass.MethodGroup:
 291                         case ExprClass.Invalid:
 292                                 throw new Exception ("Should have got the " + left_e.ExprClass +
 293                                                      " handled before");
 294                         }
 295
 296                         return null;
 297                 }
 298
 299                 static public Expression ImplicitReferenceConversion (Expression expr, Type target_type)
 300                 {
 301                         Type expr_type = expr.Type;
 302
 303                         if (target_type == TypeManager.object_type) {
 304                                 if (expr_type.IsClass)
 305                                         return new EmptyCast (expr, target_type);
 306                                 if (expr_type.IsValueType)
 307                                         return new BoxedCast (expr);
 308                         } else if (expr_type.IsSubclassOf (target_type))
 309                                 return new EmptyCast (expr, target_type);
 310                         else
 311                                 // FIXME: missing implicit reference conversions:
 312                                 //
 313                                 // from any class-type S to any interface-type T.
 314                                 // from any interface type S to interface-type T.
 315                                 // from an array-type S to an array-type of type T
 316                                 // from an array-type to System.Array
 317                                 // from any delegate type to System.Delegate
 318                                 // from any array-type or delegate type into System.ICloneable.
 319                                 // from the null type to any reference-type.
 320
 321                                 return null;
 322
 323                         return null;
 324                 }
 325
 326                 // <summary>
 327                 //   Handles expressions like this: decimal d; d = 1;
 328                 //   and changes them into: decimal d; d = new System.Decimal (1);
 329                 // </summary>
 330                 static Expression InternalTypeConstructor (TypeContainer tc, Expression expr, Type target)
 331                 {
 332                         ArrayList args = new ArrayList ();
 333
 334                         args.Add (new Argument (expr, Argument.AType.Expression));
 335
 336                         Expression ne = new New (target.FullName, args,
 337                                                  new Location ("FIXME", 1, 1));
 338
 339                         return ne.Resolve (tc);
 340                 }
 341
 342                 static int level = 0;
 343
 344                 // <summary>
 345                 //   Converts implicitly the resolved expression `expr' into the
 346                 //   `target_type'.  It returns a new expression that can be used
 347                 //   in a context that expects a `target_type'.
 348                 // </summary>
 349                 static public Expression ConvertImplicit (TypeContainer tc, Expression expr, Type target_type)
 350                 {
 351                         Type expr_type = expr.Type;
 352
 353                         Console.WriteLine ("ConvertImplicit " + expr_type + " => " + target_type);
 354                         if (level != 0)
 355                                 throw new Exception ("Lame Loop Detector Triggered");
 356
 357                         if (expr_type == target_type)
 358                                 return expr;
 359
 360                         //
 361                         // Step 1: Built-in conversions.
 362                         //
 363                         if (expr_type == TypeManager.sbyte_type){
 364                                 //
 365                                 // From sbyte to short, int, long, float, double.
 366                                 //
 367                                 if (target_type == TypeManager.int32_type)
 368                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 369                                 if (target_type == TypeManager.int64_type)
 370                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 371                                 if (target_type == TypeManager.double_type)
 372                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 373                                 if (target_type == TypeManager.float_type)
 374                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 375                                 if (target_type == TypeManager.short_type)
 376                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 377                                 if (target_type == TypeManager.decimal_type)
 378                                         return InternalTypeConstructor (tc, expr, target_type);
 379                         } else if (expr_type == TypeManager.byte_type){
 380                                 //
 381                                 // From byte to short, ushort, int, uint, long, ulong, float, double
 382                                 //
 383                                 if ((target_type == TypeManager.short_type) ||
 384                                     (target_type == TypeManager.ushort_type) ||
 385                                     (target_type == TypeManager.int32_type) ||
 386                                     (target_type == TypeManager.uint32_type))
 387                                         return new EmptyCast (expr, target_type);
 388
 389                                 if (target_type == TypeManager.uint64_type)
 390                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 391                                 if (target_type == TypeManager.int64_type)
 392                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 393
 394                                 if (target_type == TypeManager.float_type)
 395                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 396                                 if (target_type == TypeManager.double_type)
 397                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 398                                 if (target_type == TypeManager.decimal_type)
 399                                         return InternalTypeConstructor (tc, expr, target_type);
 400                         } else if (expr_type == TypeManager.short_type){
 401                                 //
 402                                 // From short to int, long, float, double
 403                                 //
 404                                 if (target_type == TypeManager.int32_type)
 405                                         return new EmptyCast (expr, target_type);
 406                                 if (target_type == TypeManager.int64_type)
 407                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 408                                 if (target_type == TypeManager.double_type)
 409                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 410                                 if (target_type == TypeManager.float_type)
 411                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 412                                 if (target_type == TypeManager.decimal_type)
 413                                         return InternalTypeConstructor (tc, expr, target_type);
 414                         } else if (expr_type == TypeManager.ushort_type){
 415                                 //
 416                                 // From ushort to int, uint, long, ulong, float, double
 417                                 //
 418                                 if ((target_type == TypeManager.uint32_type) ||
 419                                     (target_type == TypeManager.uint64_type))
 420                                         return new EmptyCast (expr, target_type);
 421
 422                                 if (target_type == TypeManager.int32_type)
 423                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 424                                 if (target_type == TypeManager.int64_type)
 425                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 426                                 if (target_type == TypeManager.double_type)
 427                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 428                                 if (target_type == TypeManager.float_type)
 429                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 430                                 if (target_type == TypeManager.decimal_type)
 431                                         return InternalTypeConstructor (tc, expr, target_type);
 432                         } else if (expr_type == TypeManager.int32_type){
 433                                 //
 434                                 // From int to long, float, double
 435                                 //
 436                                 if (target_type == TypeManager.int64_type)
 437                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 438                                 if (target_type == TypeManager.double_type)
 439                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 440                                 if (target_type == TypeManager.float_type)
 441                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 442                                 if (target_type == TypeManager.decimal_type)
 443                                         return InternalTypeConstructor (tc, expr, target_type);
 444                         } else if (expr_type == TypeManager.uint32_type){
 445                                 //
 446                                 // From uint to long, ulong, float, double
 447                                 //
 448                                 if (target_type == TypeManager.int64_type)
 449                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 450                                 if (target_type == TypeManager.uint64_type)
 451                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 452                                 if (target_type == TypeManager.double_type)
 453                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 454                                                                OpCodes.Conv_R8);
 455                                 if (target_type == TypeManager.float_type)
 456                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 457                                                                OpCodes.Conv_R4);
 458                                 if (target_type == TypeManager.decimal_type)
 459                                         return InternalTypeConstructor (tc, expr, target_type);
 460                         } else if ((expr_type == TypeManager.uint64_type) ||
 461                                    (expr_type == TypeManager.int64_type)){
 462                                 //
 463                                 // From long to float, double
 464                                 //
 465                                 if (target_type == TypeManager.double_type)
 466                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 467                                                                OpCodes.Conv_R8);
 468                                 if (target_type == TypeManager.float_type)
 469                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 470                                                                OpCodes.Conv_R4);
 471                                 if (target_type == TypeManager.decimal_type)
 472                                         return InternalTypeConstructor (tc, expr, target_type);
 473                         } else if (expr_type == TypeManager.char_type){
 474                                 //
 475                                 // From char to ushort, int, uint, long, ulong, float, double
 476                                 //
 477                                 if ((target_type == TypeManager.ushort_type) ||
 478                                     (target_type == TypeManager.int32_type) ||
 479                                     (target_type == TypeManager.uint32_type))
 480                                         return new EmptyCast (expr, target_type);
 481                                 if (target_type == TypeManager.uint64_type)
 482                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 483                                 if (target_type == TypeManager.int64_type)
 484                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 485                                 if (target_type == TypeManager.float_type)
 486                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 487                                 if (target_type == TypeManager.double_type)
 488                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 489                                 if (target_type == TypeManager.decimal_type)
 490                                         return InternalTypeConstructor (tc, expr, target_type);
 491                         }
 492
 493                         Expression e;
 494
 495                         e = ImplicitReferenceConversion (expr, target_type);
 496                         if (e != null){
 497                                 return e;
 498                         }
 499
 500                         level++;
 501                         e = UserImplicitCast.CanConvert (tc, expr, target_type);
 502                         level--;
 503                         if (e != null)
 504                                 return e;
 505
 506                         //
 507                         //  Could not find an implicit cast.
 508                         //
 509                         return null;
 510                 }
 511
 512                 // <summary>
 513                 //   Attemps to perform an implict constant conversion of the IntLiteral
 514                 //   into a different data type using casts (See Implicit Constant
 515                 //   Expression Conversions)
 516                 // </summary>
 517                 static protected Expression TryImplicitIntConversion (Type target_type, IntLiteral il)
 518                 {
 519                         int value = il.Value;
 520
 521                         if (target_type == TypeManager.sbyte_type){
 522                                 if (value >= SByte.MinValue && value <= SByte.MaxValue)
 523                                         return il;
 524                         } else if (target_type == TypeManager.byte_type){
 525                                 if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
 526                                         return il;
 527                         } else if (target_type == TypeManager.short_type){
 528                                 if (value >= Int16.MinValue && value <= Int16.MaxValue)
 529                                         return il;
 530                         } else if (target_type == TypeManager.ushort_type){
 531                                 if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
 532                                         return il;
 533                         } else if (target_type == TypeManager.uint32_type){
 534                                 //
 535                                 // we can optimize this case: a positive int32
 536                                 // always fits on a uint32
 537                                 //
 538                                 if (value >= 0)
 539                                         return il;
 540                         } else if (target_type == TypeManager.uint64_type){
 541                                 //
 542                                 // we can optimize this case: a positive int32
 543                                 // always fits on a uint64.  But we need an opcode
 544                                 // to do it.
 545                                 //
 546                                 if (value >= 0)
 547                                         return new OpcodeCast (il, target_type, OpCodes.Conv_I8);
 548                         }
 549
 550                         return null;
 551                 }
 552
 553                 // <summary>
 554                 //   Attemptes to implicityly convert `target' into `type', using
 555                 //   ConvertImplicit.  If there is no implicit conversion, then
 556                 //   an error is signaled
 557                 // </summary>
 558                 static public Expression ConvertImplicitRequired (TypeContainer tc, Expression target,
 559                                                                   Type type, Location l)
 560                 {
 561                         Expression e;
 562
 563                         e = ConvertImplicit (tc, target, type);
 564                         if (e != null)
 565                                 return e;
 566
 567                         //
 568                         // Attempt to do the implicit constant expression conversions
 569
 570                         if (target is IntLiteral){
 571                                 e = TryImplicitIntConversion (type, (IntLiteral) target);
 572                                 if (e != null)
 573                                         return e;
 574                         } else if (target is LongLiteral){
 575                                 //
 576                                 // Try the implicit constant expression conversion
 577                                 // from long to ulong, instead of a nice routine,
 578                                 // we just inline it
 579                                 //
 580                                 if (((LongLiteral) target).Value > 0)
 581                                         return target;
 582                         }
 583
 584                         string msg = "Can not convert implicitly from `"+
 585                                 TypeManager.CSharpName (target.Type) + "' to `" +
 586                                 TypeManager.CSharpName (type) + "'";
 587
 588                         Error (tc, 29, l, msg);
 589
 590                         return null;
 591                 }
 592
 593                 // <summary>
 594                 //   Performs the explicit numeric conversions
 595                 // </summary>
 596                 static Expression ConvertNumericExplicit (TypeContainer tc, Expression expr,
 597                                                           Type target_type)
 598                 {
 599                         Type expr_type = expr.Type;
 600
 601                         if (expr_type == TypeManager.sbyte_type){
 602                                 //
 603                                 // From sbyte to byte, ushort, uint, ulong, char
 604                                 //
 605                                 if (target_type == TypeManager.byte_type)
 606                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
 607                                 if (target_type == TypeManager.ushort_type)
 608                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 609                                 if (target_type == TypeManager.uint32_type)
 610                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
 611                                 if (target_type == TypeManager.uint64_type)
 612                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 613                                 if (target_type == TypeManager.char_type)
 614                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 615                         } else if (expr_type == TypeManager.byte_type){
 616                                 //
 617                                 // From byte to sbyte and char
 618                                 //
 619                                 if (target_type == TypeManager.sbyte_type)
 620                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
 621                                 if (target_type == TypeManager.char_type)
 622                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 623                         } else if (expr_type == TypeManager.short_type){
 624                                 //
 625                                 // From short to sbyte, byte, ushort, uint, ulong, char
 626                                 //
 627                                 if (target_type == TypeManager.sbyte_type)
 628                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
 629                                 if (target_type == TypeManager.byte_type)
 630                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
 631                                 if (target_type == TypeManager.ushort_type)
 632                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 633                                 if (target_type == TypeManager.uint32_type)
 634                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
 635                                 if (target_type == TypeManager.uint64_type)
 636                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 637                                 if (target_type == TypeManager.char_type)
 638                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 639                         } else if (expr_type == TypeManager.ushort_type){
 640                                 //
 641                                 // From ushort to sbyte, byte, short, char
 642                                 //
 643                                 if (target_type == TypeManager.sbyte_type)
 644                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
 645                                 if (target_type == TypeManager.byte_type)
 646                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
 647                                 if (target_type == TypeManager.short_type)
 648                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 649                                 if (target_type == TypeManager.char_type)
 650                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 651                         } else if (expr_type == TypeManager.int32_type){
 652                                 //
 653                                 // From int to sbyte, byte, short, ushort, uint, ulong, char
 654                                 //
 655                                 if (target_type == TypeManager.sbyte_type)
 656                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
 657                                 if (target_type == TypeManager.byte_type)
 658                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
 659                                 if (target_type == TypeManager.short_type)
 660                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 661                                 if (target_type == TypeManager.ushort_type)
 662                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 663                                 if (target_type == TypeManager.uint32_type)
 664                                         return new EmptyCast (expr, target_type);
 665                                 if (target_type == TypeManager.uint64_type)
 666                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 667                                 if (target_type == TypeManager.char_type)
 668                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 669                         } else if (expr_type == TypeManager.uint32_type){
 670                                 //
 671                                 // From uint to sbyte, byte, short, ushort, int, char
 672                                 //
 673                                 if (target_type == TypeManager.sbyte_type)
 674                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
 675                                 if (target_type == TypeManager.byte_type)
 676                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
 677                                 if (target_type == TypeManager.short_type)
 678                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 679                                 if (target_type == TypeManager.ushort_type)
 680                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 681                                 if (target_type == TypeManager.int32_type)
 682                                         return new EmptyCast (expr, target_type);
 683                                 if (target_type == TypeManager.char_type)
 684                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 685                         } else if (expr_type == TypeManager.int64_type){
 686                                 //
 687                                 // From long to sbyte, byte, short, ushort, int, uint, ulong, char
 688                                 //
 689                                 if (target_type == TypeManager.sbyte_type)
 690                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
 691                                 if (target_type == TypeManager.byte_type)
 692                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
 693                                 if (target_type == TypeManager.short_type)
 694                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 695                                 if (target_type == TypeManager.ushort_type)
 696                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 697                                 if (target_type == TypeManager.int32_type)
 698                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 699                                 if (target_type == TypeManager.uint32_type)
 700                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
 701                                 if (target_type == TypeManager.uint64_type)
 702                                         return new EmptyCast (expr, target_type);
 703                                 if (target_type == TypeManager.char_type)
 704                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 705                         } else if (expr_type == TypeManager.uint64_type){
 706                                 //
 707                                 // From ulong to sbyte, byte, short, ushort, int, uint, long, char
 708                                 //
 709                                 if (target_type == TypeManager.sbyte_type)
 710                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
 711                                 if (target_type == TypeManager.byte_type)
 712                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
 713                                 if (target_type == TypeManager.short_type)
 714                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 715                                 if (target_type == TypeManager.ushort_type)
 716                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 717                                 if (target_type == TypeManager.int32_type)
 718                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 719                                 if (target_type == TypeManager.uint32_type)
 720                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
 721                                 if (target_type == TypeManager.int64_type)
 722                                         return new EmptyCast (expr, target_type);
 723                                 if (target_type == TypeManager.char_type)
 724                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 725                         } else if (expr_type == TypeManager.char_type){
 726                                 //
 727                                 // From char to sbyte, byte, short
 728                                 //
 729                                 if (target_type == TypeManager.sbyte_type)
 730                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
 731                                 if (target_type == TypeManager.byte_type)
 732                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
 733                                 if (target_type == TypeManager.short_type)
 734                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 735                         } else if (expr_type == TypeManager.float_type){
 736                                 //
 737                                 // From float to sbyte, byte, short,
 738                                 // ushort, int, uint, long, ulong, char
 739                                 // or decimal
 740                                 //
 741                                 if (target_type == TypeManager.sbyte_type)
 742                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
 743                                 if (target_type == TypeManager.byte_type)
 744                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
 745                                 if (target_type == TypeManager.short_type)
 746                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 747                                 if (target_type == TypeManager.ushort_type)
 748                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 749                                 if (target_type == TypeManager.int32_type)
 750                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 751                                 if (target_type == TypeManager.uint32_type)
 752                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
 753                                 if (target_type == TypeManager.int64_type)
 754                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 755                                 if (target_type == TypeManager.uint64_type)
 756                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 757                                 if (target_type == TypeManager.char_type)
 758                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 759                                 if (target_type == TypeManager.decimal_type)
 760                                         return InternalTypeConstructor (tc, expr, target_type);
 761                         } else if (expr_type == TypeManager.double_type){
 762                                 //
 763                                 // From double to byte, byte, short,
 764                                 // ushort, int, uint, long, ulong,
 765                                 // char, float or decimal
 766                                 //
 767                                 if (target_type == TypeManager.sbyte_type)
 768                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
 769                                 if (target_type == TypeManager.byte_type)
 770                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
 771                                 if (target_type == TypeManager.short_type)
 772                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 773                                 if (target_type == TypeManager.ushort_type)
 774                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 775                                 if (target_type == TypeManager.int32_type)
 776                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 777                                 if (target_type == TypeManager.uint32_type)
 778                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
 779                                 if (target_type == TypeManager.int64_type)
 780                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 781                                 if (target_type == TypeManager.uint64_type)
 782                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 783                                 if (target_type == TypeManager.char_type)
 784                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
 785                                 if (target_type == TypeManager.float_type)
 786                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 787                                 if (target_type == TypeManager.decimal_type)
 788                                         return InternalTypeConstructor (tc, expr, target_type);
 789                         }
 790
 791                         // decimal is taken care of by the op_Explicit methods.
 792
 793                         return null;
 794                 }
 795
 796                 // <summary>
 797                 //   Performs an explicit conversion of the expression `expr' whose
 798                 //   type is expr.Type to `target_type'.
 799                 // </summary>
 800                 static public Expression ConvertExplicit (TypeContainer tc, Expression expr,
 801                                                           Type target_type)
 802                 {
 803                         Expression ne = ConvertImplicit (tc, expr, target_type);
 804
 805                         if (ne != null)
 806                                 return ne;
 807
 808                         ne = ConvertNumericExplicit (tc, expr, target_type);
 809                         if (ne != null)
 810                                 return ne;
 811
 812
 813                         return expr;
 814                 }
 815
 816                 static string ExprClassName (ExprClass c)
 817                 {
 818                         switch (c){
 819                         case ExprClass.Invalid:
 820                                 return "Invalid";
 821                         case ExprClass.Value:
 822                                 return "value";
 823                         case ExprClass.Variable:
 824                                 return "variable";
 825                         case ExprClass.Namespace:
 826                                 return "namespace";
 827                         case ExprClass.Type:
 828                                 return "type";
 829                         case ExprClass.MethodGroup:
 830                                 return "method group";
 831                         case ExprClass.PropertyAccess:
 832                                 return "property access";
 833                         case ExprClass.EventAccess:
 834                                 return "event access";
 835                         case ExprClass.IndexerAccess:
 836                                 return "indexer access";
 837                         case ExprClass.Nothing:
 838                                 return "null";
 839                         }
 840                         throw new Exception ("Should not happen");
 841                 }
 842
 843                 // <summary>
 844                 //   Reports that we were expecting `expr' to be of class `expected'
 845                 // </summary>
 846                 protected void report118 (TypeContainer tc, Expression expr, string expected)
 847                 {
 848                         Error (tc, 118, "Expression denotes a '" + ExprClassName (expr.ExprClass) +
 849                                "' where an " + expected + " was expected");
 850                 }
 851         }
 852
 853         // <summary>
 854         //   This is just a base class for expressions that can
 855         //   appear on statements (invocations, object creation,
 856         //   assignments, post/pre increment and decrement).  The idea
 857         //   being that they would support an extra Emition interface that
 858         //   does not leave a result on the stack.
 859         // </summary>
 860
 861         public abstract class ExpressionStatement : Expression {
 862
 863                 // <summary>
 864                 //   Requests the expression to be emitted in a `statement'
 865                 //   context.  This means that no new value is left on the
 866                 //   stack after invoking this method (constrasted with
 867                 //   Emit that will always leave a value on the stack).
 868                 // </summary>
 869                 public abstract void EmitStatement (EmitContext ec);
 870         }
 871
 872         // <summary>
 873         //   This kind of cast is used to encapsulate the child
 874         //   whose type is child.Type into an expression that is
 875         //   reported to return "return_type".  This is used to encapsulate
 876         //   expressions which have compatible types, but need to be dealt
 877         //   at higher levels with.
 878         //
 879         //   For example, a "byte" expression could be encapsulated in one
 880         //   of these as an "unsigned int".  The type for the expression
 881         //   would be "unsigned int".
 882         //
 883         // </summary>
 884
 885         public class EmptyCast : Expression {
 886                 protected Expression child;
 887
 888                 public EmptyCast (Expression child, Type return_type)
 889                 {
 890                         ExprClass = child.ExprClass;
 891                         type = return_type;
 892                         this.child = child;
 893                 }
 894
 895                 public override Expression Resolve (TypeContainer tc)
 896                 {
 897                         // This should never be invoked, we are born in fully
 898                         // initialized state.
 899
 900                         return this;
 901                 }
 902
 903                 public override void Emit (EmitContext ec)
 904                 {
 905                         child.Emit (ec);
 906                 }
 907         }
 908
 909         // <summary>
 910         //   This kind of cast is used to encapsulate Value Types in objects.
 911         //
 912         //   The effect of it is to box the value type emitted by the previous
 913         //   operation.
 914         // </summary>
 915         public class BoxedCast : EmptyCast {
 916
 917                 public BoxedCast (Expression expr)
 918                         : base (expr, TypeManager.object_type)
 919                 {
 920                 }
 921
 922                 public override Expression Resolve (TypeContainer tc)
 923                 {
 924                         // This should never be invoked, we are born in fully
 925                         // initialized state.
 926
 927                         return this;
 928                 }
 929
 930                 public override void Emit (EmitContext ec)
 931                 {
 932                         base.Emit (ec);
 933                         ec.ig.Emit (OpCodes.Box, child.Type);
 934                 }
 935         }
 936
 937         // <summary>
 938         //   This kind of cast is used to encapsulate a child expression
 939         //   that can be trivially converted to a target type using one or
 940         //   two opcodes.  The opcodes are passed as arguments.
 941         // </summary>
 942         public class OpcodeCast : EmptyCast {
 943                 OpCode op, op2;
 944                 bool second_valid;
 945
 946                 public OpcodeCast (Expression child, Type return_type, OpCode op)
 947                         : base (child, return_type)
 948
 949                 {
 950                         this.op = op;
 951                         second_valid = false;
 952                 }
 953
 954                 public OpcodeCast (Expression child, Type return_type, OpCode op, OpCode op2)
 955                         : base (child, return_type)
 956
 957                 {
 958                         this.op = op;
 959                         this.op2 = op2;
 960                         second_valid = true;
 961                 }
 962
 963                 public override Expression Resolve (TypeContainer tc)
 964                 {
 965                         // This should never be invoked, we are born in fully
 966                         // initialized state.
 967
 968                         return this;
 969                 }
 970
 971                 public override void Emit (EmitContext ec)
 972                 {
 973                         base.Emit (ec);
 974                         ec.ig.Emit (op);
 975
 976                         if (second_valid)
 977                                 ec.ig.Emit (op2);
 978                 }
 979
 980         }
 981
 982         // <summary>
 983         //   Unary expressions.
 984         // </summary>
 985         //
 986         // <remarks>
 987         //   Unary implements unary expressions.   It derives from
 988         //   ExpressionStatement becuase the pre/post increment/decrement
 989         //   operators can be used in a statement context.
 990         // </remarks>
 991         public class Unary : ExpressionStatement {
 992                 public enum Operator {
 993                         Addition, Subtraction, Negate, BitComplement,
 994                         Indirection, AddressOf, PreIncrement,
 995                         PreDecrement, PostIncrement, PostDecrement
 996                 }
 997
 998                 Operator   oper;
 999                 Expression expr;
1000                 ArrayList  Arguments;
1001                 MethodBase method;
1002                 Location   location;
1003
1004                 public Unary (Operator op, Expression expr, Location loc)
1005                 {
1006                         this.oper = op;
1007                         this.expr = expr;
1008                         this.location = loc;
1009                 }
1010
1011                 public Expression Expr {
1012                         get {
1013                                 return expr;
1014                         }
1015
1016                         set {
1017                                 expr = value;
1018                         }
1019                 }
1020
1021                 public Operator Oper {
1022                         get {
1023                                 return oper;
1024                         }
1025
1026                         set {
1027                                 oper = value;
1028                         }
1029                 }
1030
1031                 // <summary>
1032                 //   Returns a stringified representation of the Operator
1033                 // </summary>
1034                 string OperName ()
1035                 {
1036                         switch (oper){
1037                         case Operator.Addition:
1038                                 return "+";
1039                         case Operator.Subtraction:
1040                                 return "-";
1041                         case Operator.Negate:
1042                                 return "!";
1043                         case Operator.BitComplement:
1044                                 return "~";
1045                         case Operator.AddressOf:
1046                                 return "&";
1047                         case Operator.Indirection:
1048                                 return "*";
1049                         case Operator.PreIncrement : case Operator.PostIncrement :
1050                                 return "++";
1051                         case Operator.PreDecrement : case Operator.PostDecrement :
1052                                 return "--";
1053                         }
1054
1055                         return oper.ToString ();
1056                 }
1057
1058                 Expression ForceConversion (TypeContainer tc, Expression expr, Type target_type)
1059                 {
1060                         if (expr.Type == target_type)
1061                                 return expr;
1062
1063                         return ConvertImplicit (tc, expr, target_type);
1064                 }
1065
1066                 void report23 (Report r, Type t)
1067                 {
1068                         r.Error (23, "Operator " + OperName () + " cannot be applied to operand of type `" +
1069                                  TypeManager.CSharpName (t) + "'");
1070                 }
1071
1072                 // <summary>
1073                 //   Returns whether an object of type `t' can be incremented
1074                 //   or decremented with add/sub (ie, basically whether we can
1075                 //   use pre-post incr-decr operations on it, but it is not a
1076                 //   System.Decimal, which we test elsewhere)
1077                 // </summary>
1078                 static bool IsIncrementableNumber (Type t)
1079                 {
1080                         return (t == TypeManager.sbyte_type) ||
1081                                 (t == TypeManager.byte_type) ||
1082                                 (t == TypeManager.short_type) ||
1083                                 (t == TypeManager.ushort_type) ||
1084                                 (t == TypeManager.int32_type) ||
1085                                 (t == TypeManager.uint32_type) ||
1086                                 (t == TypeManager.int64_type) ||
1087                                 (t == TypeManager.uint64_type) ||
1088                                 (t == TypeManager.char_type) ||
1089                                 (t.IsSubclassOf (TypeManager.enum_type)) ||
1090                                 (t == TypeManager.float_type) ||
1091                                 (t == TypeManager.double_type);
1092                 }
1093
1094                 Expression ResolveOperator (TypeContainer tc)
1095                 {
1096                         Type expr_type = expr.Type;
1097
1098                         //
1099                         // Step 1: Perform Operator Overload location
1100                         //
1101                         Expression mg;
1102                         string op_name;
1103
1104                         if (oper == Operator.PostIncrement || oper == Operator.PreIncrement)
1105                                 op_name = "op_Increment";
1106                         else if (oper == Operator.PostDecrement || oper == Operator.PreDecrement)
1107                                 op_name = "op_Decrement";
1108                         else
1109                                 op_name = "op_" + oper;
1110
1111                         mg = MemberLookup (tc, expr_type, op_name, false);
1112
1113                         if (mg != null) {
1114                                 Arguments = new ArrayList ();
1115                                 Arguments.Add (new Argument (expr, Argument.AType.Expression));
1116
1117                                 method = Invocation.OverloadResolve (tc, (MethodGroupExpr) mg, Arguments, location);
1118                                 if (method != null) {
1119                                         MethodInfo mi = (MethodInfo) method;
1120
1121                                         type = mi.ReturnType;
1122                                         return this;
1123                                 }
1124                         }
1125
1126                         //
1127                         // Step 2: Default operations on CLI native types.
1128                         //
1129
1130                         // Only perform numeric promotions on:
1131                         // +, -, ++, --
1132
1133                         if (expr_type == null)
1134                                 return null;
1135
1136                         if (oper == Operator.Negate){
1137                                 if (expr_type != TypeManager.bool_type) {
1138                                         report23 (tc.RootContext.Report, expr.Type);
1139                                         return null;
1140                                 }
1141
1142                                 type = TypeManager.bool_type;
1143                                 return this;
1144                         }
1145
1146                         if (oper == Operator.BitComplement) {
1147                                 if (!((expr_type == TypeManager.int32_type) ||
1148                                       (expr_type == TypeManager.uint32_type) ||
1149                                       (expr_type == TypeManager.int64_type) ||
1150                                       (expr_type == TypeManager.uint64_type) ||
1151                                       (expr_type.IsSubclassOf (TypeManager.enum_type)))){
1152                                         report23 (tc.RootContext.Report, expr.Type);
1153                                         return null;
1154                                 }
1155                                 type = expr_type;
1156                                 return this;
1157                         }
1158
1159                         if (oper == Operator.Addition) {
1160                                 //
1161                                 // A plus in front of something is just a no-op, so return the child.
1162                                 //
1163                                 return expr;
1164                         }
1165
1166                         //
1167                         // Deals with -literals
1168                         // int     operator- (int x)
1169                         // long    operator- (long x)
1170                         // float   operator- (float f)
1171                         // double  operator- (double d)
1172                         // decimal operator- (decimal d)
1173                         //
1174                         if (oper == Operator.Subtraction){
1175                                 //
1176                                 // Fold a "- Constant" into a negative constant
1177                                 //
1178
1179                                 Expression e = null;
1180
1181                                 //
1182                                 // Is this a constant?
1183                                 //
1184                                 if (expr is IntLiteral)
1185                                         e = new IntLiteral (-((IntLiteral) expr).Value);
1186                                 else if (expr is LongLiteral)
1187                                         e = new LongLiteral (-((LongLiteral) expr).Value);
1188                                 else if (expr is FloatLiteral)
1189                                         e = new FloatLiteral (-((FloatLiteral) expr).Value);
1190                                 else if (expr is DoubleLiteral)
1191                                         e = new DoubleLiteral (-((DoubleLiteral) expr).Value);
1192                                 else if (expr is DecimalLiteral)
1193                                         e = new DecimalLiteral (-((DecimalLiteral) expr).Value);
1194
1195                                 if (e != null){
1196                                         e = e.Resolve (tc);
1197                                         return e;
1198                                 }
1199
1200                                 //
1201                                 // Not a constant we can optimize, perform numeric
1202                                 // promotions to int, long, double.
1203                                 //
1204                                 //
1205                                 // The following is inneficient, because we call
1206                                 // ConvertImplicit too many times.
1207                                 //
1208                                 // It is also not clear if we should convert to Float
1209                                 // or Double initially.
1210                                 //
1211                                 if (expr_type == TypeManager.uint32_type){
1212                                         //
1213                                         // FIXME: handle exception to this rule that
1214                                         // permits the int value -2147483648 (-2^31) to
1215                                         // bt written as a decimal interger literal
1216                                         //
1217                                         type = TypeManager.int64_type;
1218                                         expr = ConvertImplicit (tc, expr, type);
1219                                         return this;
1220                                 }
1221
1222                                 if (expr_type == TypeManager.uint64_type){
1223                                         //
1224                                         // FIXME: Handle exception of `long value'
1225                                         // -92233720368547758087 (-2^63) to be written as
1226                                         // decimal integer literal.
1227                                         //
1228                                         report23 (tc.RootContext.Report, expr_type);
1229                                         return null;
1230                                 }
1231
1232                                 e = ConvertImplicit (tc, expr, TypeManager.int32_type);
1233                                 if (e != null){
1234                                         expr = e;
1235                                         type = e.Type;
1236                                         return this;
1237                                 }
1238
1239                                 e = ConvertImplicit (tc, expr, TypeManager.int64_type);
1240                                 if (e != null){
1241                                         expr = e;
1242                                         type = e.Type;
1243                                         return this;
1244                                 }
1245
1246                                 e = ConvertImplicit (tc, expr, TypeManager.double_type);
1247                                 if (e != null){
1248                                         expr = e;
1249                                         type = e.Type;
1250                                         return this;
1251                                 }
1252
1253                                 report23 (tc.RootContext.Report, expr_type);
1254                                 return null;
1255                         }
1256
1257                         //
1258                         // The operand of the prefix/postfix increment decrement operators
1259                         // should be an expression that is classified as a variable,
1260                         // a property access or an indexer access
1261                         //
1262                         if (oper == Operator.PreDecrement || oper == Operator.PreIncrement ||
1263                             oper == Operator.PostDecrement || oper == Operator.PostIncrement){
1264                                 if (expr.ExprClass == ExprClass.Variable){
1265                                         if (IsIncrementableNumber (expr_type) ||
1266                                             expr_type == TypeManager.decimal_type){
1267                                                 type = expr_type;
1268                                                 return this;
1269                                         }
1270                                 } else if (expr.ExprClass == ExprClass.IndexerAccess){
1271                                         //
1272                                         // FIXME: Verify that we have both get and set methods
1273                                         //
1274                                         throw new Exception ("Implement me");
1275                                 } else if (expr.ExprClass == ExprClass.PropertyAccess){
1276                                         //
1277                                         // FIXME: Verify that we have both get and set methods
1278                                         //
1279                                         throw new Exception ("Implement me");
1280                                 } else {
1281                                         report118 (tc, expr, "variable, indexer or property access");
1282                                 }
1283                         }
1284
1285                         if (oper == Operator.AddressOf){
1286                                 if (expr.ExprClass != ExprClass.Variable){
1287                                         Error (tc, 211, "Cannot take the address of non-variables");
1288                                         return null;
1289                                 }
1290                                 type = Type.GetType (expr.Type.ToString () + "*");
1291                         }
1292
1293                         Error (tc, 187, "No such operator '" + OperName () + "' defined for type '" +
1294                                TypeManager.CSharpName (expr_type) + "'");
1295                         return null;
1296
1297                 }
1298
1299                 public override Expression Resolve (TypeContainer tc)
1300                 {
1301                         expr = expr.Resolve (tc);
1302
1303                         if (expr == null)
1304                                 return null;
1305
1306                         return ResolveOperator (tc);
1307                 }
1308
1309                 public override void Emit (EmitContext ec)
1310                 {
1311                         ILGenerator ig = ec.ig;
1312                         Type expr_type = expr.Type;
1313
1314                         if (method != null) {
1315
1316                                 // Note that operators are static anyway
1317
1318                                 if (Arguments != null)
1319                                         Invocation.EmitArguments (ec, method, Arguments);
1320
1321                                 //
1322                                 // Post increment/decrement operations need a copy at this
1323                                 // point.
1324                                 //
1325                                 if (oper == Operator.PostDecrement || oper == Operator.PostIncrement)
1326                                         ig.Emit (OpCodes.Dup);
1327
1328
1329                                 ig.Emit (OpCodes.Call, (MethodInfo) method);
1330
1331                                 //
1332                                 // Pre Increment and Decrement operators
1333                                 //
1334                                 if (oper == Operator.PreIncrement || oper == Operator.PreDecrement){
1335                                         ig.Emit (OpCodes.Dup);
1336                                 }
1337
1338                                 //
1339                                 // Increment and Decrement should store the result
1340                                 //
1341                                 if (oper == Operator.PreDecrement || oper == Operator.PreIncrement ||
1342                                     oper == Operator.PostDecrement || oper == Operator.PostIncrement){
1343                                         ((LValue) expr).Store (ec);
1344                                 }
1345                                 return;
1346                         }
1347
1348                         switch (oper) {
1349                         case Operator.Addition:
1350                                 throw new Exception ("This should be caught by Resolve");
1351
1352                         case Operator.Subtraction:
1353                                 expr.Emit (ec);
1354                                 ig.Emit (OpCodes.Neg);
1355                                 break;
1356
1357                         case Operator.Negate:
1358                                 expr.Emit (ec);
1359                                 ig.Emit (OpCodes.Ldc_I4_0);
1360                                 ig.Emit (OpCodes.Ceq);
1361                                 break;
1362
1363                         case Operator.BitComplement:
1364                                 expr.Emit (ec);
1365                                 ig.Emit (OpCodes.Not);
1366                                 break;
1367
1368                         case Operator.AddressOf:
1369                                 ((LValue)expr).AddressOf (ec);
1370                                 break;
1371
1372                         case Operator.Indirection:
1373                                 throw new Exception ("Not implemented yet");
1374
1375                         case Operator.PreIncrement:
1376                         case Operator.PreDecrement:
1377                                 if (expr.ExprClass == ExprClass.Variable){
1378                                         //
1379                                         // Resolve already verified that it is an "incrementable"
1380                                         //
1381                                         expr.Emit (ec);
1382                                         ig.Emit (OpCodes.Ldc_I4_1);
1383
1384                                         if (oper == Operator.PreDecrement)
1385                                                 ig.Emit (OpCodes.Sub);
1386                                         else
1387                                                 ig.Emit (OpCodes.Add);
1388                                         ig.Emit (OpCodes.Dup);
1389                                         ((LValue) expr).Store (ec);
1390                                 } else {
1391                                         throw new Exception ("Handle Indexers and Properties here");
1392                                 }
1393                                 break;
1394
1395                         case Operator.PostIncrement:
1396                         case Operator.PostDecrement:
1397                                 if (expr.ExprClass == ExprClass.Variable){
1398                                         //
1399                                         // Resolve already verified that it is an "incrementable"
1400                                         //
1401                                         expr.Emit (ec);
1402                                         ig.Emit (OpCodes.Dup);
1403                                         ig.Emit (OpCodes.Ldc_I4_1);
1404
1405                                         if (oper == Operator.PostDecrement)
1406                                                 ig.Emit (OpCodes.Sub);
1407                                         else
1408                                                 ig.Emit (OpCodes.Add);
1409                                         ((LValue) expr).Store (ec);
1410                                 } else {
1411                                         throw new Exception ("Handle Indexers and Properties here");
1412                                 }
1413                                 break;
1414
1415                         default:
1416                                 throw new Exception ("This should not happen: Operator = "
1417                                                      + oper.ToString ());
1418                         }
1419                 }
1420
1421
1422                 public override void EmitStatement (EmitContext ec)
1423                 {
1424                         //
1425                         // FIXME: we should rewrite this code to generate
1426                         // better code for ++ and -- as we know we wont need
1427                         // the values on the stack
1428                         //
1429                         Emit (ec);
1430                         ec.ig.Emit (OpCodes.Pop);
1431                 }
1432         }
1433
1434         public class Probe : Expression {
1435                 public readonly string ProbeType;
1436                 public readonly Operator Oper;
1437                 Expression expr;
1438                 Type probe_type;
1439
1440                 public enum Operator {
1441                         Is, As
1442                 }
1443
1444                 public Probe (Operator oper, Expression expr, string probe_type)
1445                 {
1446                         Oper = oper;
1447                         ProbeType = probe_type;
1448                         this.expr = expr;
1449                 }
1450
1451                 public Expression Expr {
1452                         get {
1453                                 return expr;
1454                         }
1455                 }
1456
1457                 public override Expression Resolve (TypeContainer tc)
1458                 {
1459                         probe_type = tc.LookupType (ProbeType, false);
1460
1461                         if (probe_type == null)
1462                                 return null;
1463
1464                         expr = expr.Resolve (tc);
1465
1466                         type = TypeManager.bool_type;
1467                         eclass = ExprClass.Value;
1468
1469                         return this;
1470                 }
1471
1472                 public override void Emit (EmitContext ec)
1473                 {
1474                         expr.Emit (ec);
1475
1476                         if (Oper == Operator.Is){
1477                                 ec.ig.Emit (OpCodes.Isinst, probe_type);
1478                         } else {
1479                                 throw new Exception ("Implement as");
1480                         }
1481                 }
1482         }
1483
1484         // <summary>
1485         //   This represents a typecast in the source language.
1486         //
1487         //   FIXME: Cast expressions have an unusual set of parsing
1488         //   rules, we need to figure those out.
1489         // </summary>
1490         public class Cast : Expression {
1491                 string target_type;
1492                 Expression expr;
1493
1494                 public Cast (string cast_type, Expression expr)
1495                 {
1496                         this.target_type = cast_type;
1497                         this.expr = expr;
1498                 }
1499
1500                 public string TargetType {
1501                         get {
1502                                 return target_type;
1503                         }
1504                 }
1505
1506                 public Expression Expr {
1507                         get {
1508                                 return expr;
1509                         }
1510                         set {
1511                                 expr = value;
1512                         }
1513                 }
1514
1515                 public override Expression Resolve (TypeContainer tc)
1516                 {
1517                         expr = expr.Resolve (tc);
1518                         if (expr == null)
1519                                 return null;
1520
1521                         type = tc.LookupType (target_type, false);
1522                         eclass = ExprClass.Value;
1523
1524                         if (type == null)
1525                                 return null;
1526
1527                         expr = ConvertExplicit (tc, expr, type);
1528
1529                         return expr;
1530                 }
1531
1532                 public override void Emit (EmitContext ec)
1533                 {
1534                         //
1535                         // This one will never happen
1536                         //
1537                         throw new Exception ("Should not happen");
1538                 }
1539         }
1540
1541         public class Binary : Expression {
1542                 public enum Operator {
1543                         Multiply, Division, Modulus,
1544                         Addition, Subtraction,
1545                         LeftShift, RightShift,
1546                         LessThan, GreaterThan, LessThanOrEqual, GreaterThanOrEqual,
1547                         Equality, Inequality,
1548                         BitwiseAnd,
1549                         ExclusiveOr,
1550                         BitwiseOr,
1551                         LogicalAnd,
1552                         LogicalOr
1553                 }
1554
1555                 Operator oper;
1556                 Expression left, right;
1557                 MethodBase method;
1558                 ArrayList  Arguments;
1559                 Location   location;
1560
1561
1562                 public Binary (Operator oper, Expression left, Expression right, Location loc)
1563                 {
1564                         this.oper = oper;
1565                         this.left = left;
1566                         this.right = right;
1567                         this.location = loc;
1568                 }
1569
1570                 public Operator Oper {
1571                         get {
1572                                 return oper;
1573                         }
1574                         set {
1575                                 oper = value;
1576                         }
1577                 }
1578
1579                 public Expression Left {
1580                         get {
1581                                 return left;
1582                         }
1583                         set {
1584                                 left = value;
1585                         }
1586                 }
1587
1588                 public Expression Right {
1589                         get {
1590                                 return right;
1591                         }
1592                         set {
1593                                 right = value;
1594                         }
1595                 }
1596
1597
1598                 // <summary>
1599                 //   Returns a stringified representation of the Operator
1600                 // </summary>
1601                 string OperName ()
1602                 {
1603                         switch (oper){
1604                         case Operator.Multiply:
1605                                 return "*";
1606                         case Operator.Division:
1607                                 return "/";
1608                         case Operator.Modulus:
1609                                 return "%";
1610                         case Operator.Addition:
1611                                 return "+";
1612                         case Operator.Subtraction:
1613                                 return "-";
1614                         case Operator.LeftShift:
1615                                 return "<<";
1616                         case Operator.RightShift:
1617                                 return ">>";
1618                         case Operator.LessThan:
1619                                 return "<";
1620                         case Operator.GreaterThan:
1621                                 return ">";
1622                         case Operator.LessThanOrEqual:
1623                                 return "<=";
1624                         case Operator.GreaterThanOrEqual:
1625                                 return ">=";
1626                         case Operator.Equality:
1627                                 return "==";
1628                         case Operator.Inequality:
1629                                 return "!=";
1630                         case Operator.BitwiseAnd:
1631                                 return "&";
1632                         case Operator.BitwiseOr:
1633                                 return "|";
1634                         case Operator.ExclusiveOr:
1635                                 return "^";
1636                         case Operator.LogicalOr:
1637                                 return "||";
1638                         case Operator.LogicalAnd:
1639                                 return "&&";
1640                         }
1641
1642                         return oper.ToString ();
1643                 }
1644
1645                 Expression ForceConversion (TypeContainer tc, Expression expr, Type target_type)
1646                 {
1647                         if (expr.Type == target_type)
1648                                 return expr;
1649
1650                         return ConvertImplicit (tc, expr, target_type);
1651                 }
1652
1653                 //
1654                 // Note that handling the case l == Decimal || r == Decimal
1655                 // is taken care of by the Step 1 Operator Overload resolution.
1656                 //
1657                 void DoNumericPromotions (TypeContainer tc, Type l, Type r)
1658                 {
1659                         if (l == TypeManager.double_type || r == TypeManager.double_type){
1660                                 //
1661                                 // If either operand is of type double, the other operand is
1662                                 // conveted to type double.
1663                                 //
1664                                 if (r != TypeManager.double_type)
1665                                         right = ConvertImplicit (tc, right, TypeManager.double_type);
1666                                 if (l != TypeManager.double_type)
1667                                         left = ConvertImplicit (tc, left, TypeManager.double_type);
1668
1669                                 type = TypeManager.double_type;
1670                         } else if (l == TypeManager.float_type || r == TypeManager.float_type){
1671                                 //
1672                                 // if either operand is of type float, th eother operand is
1673                                 // converd to type float.
1674                                 //
1675                                 if (r != TypeManager.double_type)
1676                                         right = ConvertImplicit (tc, right, TypeManager.float_type);
1677                                 if (l != TypeManager.double_type)
1678                                         left = ConvertImplicit (tc, left, TypeManager.float_type);
1679                                 type = TypeManager.float_type;
1680                         } else if (l == TypeManager.uint64_type || r == TypeManager.uint64_type){
1681                                 //
1682                                 // If either operand is of type ulong, the other operand is
1683                                 // converted to type ulong.  or an error ocurrs if the other
1684                                 // operand is of type sbyte, short, int or long
1685                                 //
1686                                 Type other = null;
1687
1688                                 if (l == TypeManager.uint64_type)
1689                                         other = r;
1690                                 else if (r == TypeManager.uint64_type)
1691                                         other = l;
1692
1693                                 if ((other == TypeManager.sbyte_type) ||
1694                                     (other == TypeManager.short_type) ||
1695                                     (other == TypeManager.int32_type) ||
1696                                     (other == TypeManager.int64_type)){
1697                                         string oper = OperName ();
1698
1699                                         Error (tc, 34, "Operator `" + OperName ()
1700                                                + "' is ambiguous on operands of type `"
1701                                                + TypeManager.CSharpName (l) + "' "
1702                                                + "and `" + TypeManager.CSharpName (r)
1703                                                + "'");
1704                                 }
1705                                 type = TypeManager.uint64_type;
1706                         } else if (l == TypeManager.int64_type || r == TypeManager.int64_type){
1707                                 //
1708                                 // If either operand is of type long, the other operand is converted
1709                                 // to type long.
1710                                 //
1711                                 if (l != TypeManager.int64_type)
1712                                         left = ConvertImplicit (tc, left, TypeManager.int64_type);
1713                                 if (r != TypeManager.int64_type)
1714                                         right = ConvertImplicit (tc, right, TypeManager.int64_type);
1715
1716                                 type = TypeManager.int64_type;
1717                         } else if (l == TypeManager.uint32_type || r == TypeManager.uint32_type){
1718                                 //
1719                                 // If either operand is of type uint, and the other
1720                                 // operand is of type sbyte, short or int, othe operands are
1721                                 // converted to type long.
1722                                 //
1723                                 Type other = null;
1724
1725                                 if (l == TypeManager.uint32_type)
1726                                         other = r;
1727                                 else if (r == TypeManager.uint32_type)
1728                                         other = l;
1729
1730                                 if ((other == TypeManager.sbyte_type) ||
1731                                     (other == TypeManager.short_type) ||
1732                                     (other == TypeManager.int32_type)){
1733                                         left = ForceConversion (tc, left, TypeManager.int64_type);
1734                                         right = ForceConversion (tc, right, TypeManager.int64_type);
1735                                         type = TypeManager.int64_type;
1736                                 } else {
1737                                         //
1738                                         // if either operand is of type uint, the other
1739                                         // operand is converd to type uint
1740                                         //
1741                                         left = ForceConversion (tc, left, TypeManager.uint32_type);
1742                                         right = ForceConversion (tc, left, TypeManager.uint32_type);
1743                                         type = TypeManager.uint32_type;
1744                                 }
1745                         } else if (l == TypeManager.decimal_type || r == TypeManager.decimal_type){
1746                                 if (l != TypeManager.decimal_type)
1747                                         left = ConvertImplicit (tc, left, TypeManager.decimal_type);
1748                                 if (r != TypeManager.decimal_type)
1749                                         right = ConvertImplicit (tc, right, TypeManager.decimal_type);
1750
1751                                 type = TypeManager.decimal_type;
1752                         } else {
1753                                 left = ForceConversion (tc, left, TypeManager.int32_type);
1754                                 right = ForceConversion (tc, right, TypeManager.int32_type);
1755                                 type = TypeManager.int32_type;
1756                         }
1757                 }
1758
1759                 void error19 (TypeContainer tc)
1760                 {
1761                         Error (tc, 19,
1762                                "Operator " + OperName () + " cannot be applied to operands of type `" +
1763                                TypeManager.CSharpName (left.Type) + "' and `" +
1764                                TypeManager.CSharpName (right.Type) + "'");
1765
1766                 }
1767
1768                 Expression CheckShiftArguments (TypeContainer tc)
1769                 {
1770                         Expression e;
1771                         Type l = left.Type;
1772                         Type r = right.Type;
1773
1774                         e = ForceConversion (tc, right, TypeManager.int32_type);
1775                         if (e == null){
1776                                 error19 (tc);
1777                                 return null;
1778                         }
1779                         right = e;
1780
1781                         if (((e = ConvertImplicit (tc, left, TypeManager.int32_type)) != null) ||
1782                             ((e = ConvertImplicit (tc, left, TypeManager.uint32_type)) != null) ||
1783                             ((e = ConvertImplicit (tc, left, TypeManager.int64_type)) != null) ||
1784                             ((e = ConvertImplicit (tc, left, TypeManager.uint64_type)) != null)){
1785                                 left = e;
1786
1787                                 return this;
1788                         }
1789                         error19 (tc);
1790                         return null;
1791                 }
1792
1793                 Expression ResolveOperator (TypeContainer tc)
1794                 {
1795                         Type l = left.Type;
1796                         Type r = right.Type;
1797
1798                         //
1799                         // Step 1: Perform Operator Overload location
1800                         //
1801                         Expression left_expr, right_expr;
1802
1803                         string op = "op_" + oper;
1804
1805                         left_expr = MemberLookup (tc, l, op, false);
1806
1807                         right_expr = MemberLookup (tc, r, op, false);
1808
1809                         MethodGroupExpr union = Invocation.MakeUnionSet (left_expr, right_expr);
1810
1811                         Arguments = new ArrayList ();
1812                         Arguments.Add (new Argument (left, Argument.AType.Expression));
1813                         Arguments.Add (new Argument (right, Argument.AType.Expression));
1814
1815                         if (union != null) {
1816                                 method = Invocation.OverloadResolve (tc, union, Arguments, location);
1817                                 if (method != null) {
1818                                         MethodInfo mi = (MethodInfo) method;
1819
1820                                         type = mi.ReturnType;
1821                                         return this;
1822                                 }
1823                         }
1824
1825                         //
1826                         // Step 2: Default operations on CLI native types.
1827                         //
1828
1829                         // Only perform numeric promotions on:
1830                         // +, -, *, /, %, &, |, ^, ==, !=, <, >, <=, >=
1831                         //
1832                         if (oper == Operator.LeftShift || oper == Operator.RightShift){
1833                                 return CheckShiftArguments (tc);
1834                         } else if (oper == Operator.LogicalOr || oper == Operator.LogicalAnd){
1835
1836                                 if (l != TypeManager.bool_type || r != TypeManager.bool_type)
1837                                         error19 (tc);
1838                         } else
1839                                 DoNumericPromotions (tc, l, r);
1840
1841                         if (left == null || right == null)
1842                                 return null;
1843
1844                         if (oper == Operator.BitwiseAnd ||
1845                             oper == Operator.BitwiseOr ||
1846                             oper == Operator.ExclusiveOr){
1847                                 if (!((l == TypeManager.int32_type) ||
1848                                       (l == TypeManager.uint32_type) ||
1849                                       (l == TypeManager.int64_type) ||
1850                                       (l == TypeManager.uint64_type))){
1851                                         error19 (tc);
1852                                         return null;
1853                                 }
1854                         }
1855
1856                         if (oper == Operator.Equality ||
1857                             oper == Operator.Inequality ||
1858                             oper == Operator.LessThanOrEqual ||
1859                             oper == Operator.LessThan ||
1860                             oper == Operator.GreaterThanOrEqual ||
1861                             oper == Operator.GreaterThan){
1862                                 type = TypeManager.bool_type;
1863                         }
1864
1865                         return this;
1866                 }
1867
1868                 public override Expression Resolve (TypeContainer tc)
1869                 {
1870                         left = left.Resolve (tc);
1871                         right = right.Resolve (tc);
1872
1873                         if (left == null || right == null)
1874                                 return null;
1875
1876                         return ResolveOperator (tc);
1877                 }
1878
1879                 public bool IsBranchable ()
1880                 {
1881                         if (oper == Operator.Equality ||
1882                             oper == Operator.Inequality ||
1883                             oper == Operator.LessThan ||
1884                             oper == Operator.GreaterThan ||
1885                             oper == Operator.LessThanOrEqual ||
1886                             oper == Operator.GreaterThanOrEqual){
1887                                 return true;
1888                         } else
1889                                 return false;
1890                 }
1891
1892                 // <summary>
1893                 //   This entry point is used by routines that might want
1894                 //   to emit a brfalse/brtrue after an expression, and instead
1895                 //   they could use a more compact notation.
1896                 //
1897                 //   Typically the code would generate l.emit/r.emit, followed
1898                 //   by the comparission and then a brtrue/brfalse.  The comparissions
1899                 //   are sometimes inneficient (there are not as complete as the branches
1900                 //   look for the hacks in Emit using double ceqs).
1901                 //
1902                 //   So for those cases we provide EmitBranchable that can emit the
1903                 //   branch with the test
1904                 // </summary>
1905                 public void EmitBranchable (EmitContext ec, int target)
1906                 {
1907                         OpCode opcode;
1908                         bool close_target = false;
1909
1910                         left.Emit (ec);
1911                         right.Emit (ec);
1912
1913                         switch (oper){
1914                         case Operator.Equality:
1915                                 if (close_target)
1916                                         opcode = OpCodes.Beq_S;
1917                                 else
1918                                         opcode = OpCodes.Beq;
1919                                 break;
1920
1921                         case Operator.Inequality:
1922                                 if (close_target)
1923                                         opcode = OpCodes.Bne_Un_S;
1924                                 else
1925                                         opcode = OpCodes.Bne_Un;
1926                                 break;
1927
1928                         case Operator.LessThan:
1929                                 if (close_target)
1930                                         opcode = OpCodes.Blt_S;
1931                                 else
1932                                         opcode = OpCodes.Blt;
1933                                 break;
1934
1935                         case Operator.GreaterThan:
1936                                 if (close_target)
1937                                         opcode = OpCodes.Bgt_S;
1938                                 else
1939                                         opcode = OpCodes.Bgt;
1940                                 break;
1941
1942                         case Operator.LessThanOrEqual:
1943                                 if (close_target)
1944                                         opcode = OpCodes.Ble_S;
1945                                 else
1946                                         opcode = OpCodes.Ble;
1947                                 break;
1948
1949                         case Operator.GreaterThanOrEqual:
1950                                 if (close_target)
1951                                         opcode = OpCodes.Bge_S;
1952                                 else
1953                                         opcode = OpCodes.Ble;
1954                                 break;
1955
1956                         default:
1957                                 throw new Exception ("EmitBranchable called on non-EmitBranchable operator: "
1958                                                      + oper.ToString ());
1959                         }
1960
1961                         ec.ig.Emit (opcode, target);
1962                 }
1963
1964                 public override void Emit (EmitContext ec)
1965                 {
1966                         ILGenerator ig = ec.ig;
1967                         Type l = left.Type;
1968                         Type r = right.Type;
1969                         OpCode opcode;
1970
1971                         if (method != null) {
1972
1973                                 // Note that operators are static anyway
1974
1975                                 if (Arguments != null)
1976                                         Invocation.EmitArguments (ec, method, Arguments);
1977
1978                                 if (method is MethodInfo)
1979                                         ig.Emit (OpCodes.Call, (MethodInfo) method);
1980                                 else
1981                                         ig.Emit (OpCodes.Call, (ConstructorInfo) method);
1982
1983                                 return;
1984                         }
1985
1986                         left.Emit (ec);
1987                         right.Emit (ec);
1988
1989                         switch (oper){
1990                         case Operator.Multiply:
1991                                 if (ec.CheckState){
1992                                         if (l == TypeManager.int32_type || l == TypeManager.int64_type)
1993                                                 opcode = OpCodes.Mul_Ovf;
1994                                         else if (l==TypeManager.uint32_type || l==TypeManager.uint64_type)
1995                                                 opcode = OpCodes.Mul_Ovf_Un;
1996                                         else
1997                                                 opcode = OpCodes.Mul;
1998                                 } else
1999                                         opcode = OpCodes.Mul;
2000
2001                                 break;
2002
2003                         case Operator.Division:
2004                                 if (l == TypeManager.uint32_type || l == TypeManager.uint64_type)
2005                                         opcode = OpCodes.Div_Un;
2006                                 else
2007                                         opcode = OpCodes.Div;
2008                                 break;
2009
2010                         case Operator.Modulus:
2011                                 if (l == TypeManager.uint32_type || l == TypeManager.uint64_type)
2012                                         opcode = OpCodes.Rem_Un;
2013                                 else
2014                                         opcode = OpCodes.Rem;
2015                                 break;
2016
2017                         case Operator.Addition:
2018                                 if (ec.CheckState){
2019                                         if (l == TypeManager.int32_type || l == TypeManager.int64_type)
2020                                                 opcode = OpCodes.Add_Ovf;
2021                                         else if (l==TypeManager.uint32_type || l==TypeManager.uint64_type)
2022                                                 opcode = OpCodes.Add_Ovf_Un;
2023                                         else
2024                                                 opcode = OpCodes.Mul;
2025                                 } else
2026                                         opcode = OpCodes.Add;
2027                                 break;
2028
2029                         case Operator.Subtraction:
2030                                 if (ec.CheckState){
2031                                         if (l == TypeManager.int32_type || l == TypeManager.int64_type)
2032                                                 opcode = OpCodes.Sub_Ovf;
2033                                         else if (l==TypeManager.uint32_type || l==TypeManager.uint64_type)
2034                                                 opcode = OpCodes.Sub_Ovf_Un;
2035                                         else
2036                                                 opcode = OpCodes.Sub;
2037                                 } else
2038                                         opcode = OpCodes.Sub;
2039                                 break;
2040
2041                         case Operator.RightShift:
2042                                 opcode = OpCodes.Shr;
2043                                 break;
2044
2045                         case Operator.LeftShift:
2046                                 opcode = OpCodes.Shl;
2047                                 break;
2048
2049                         case Operator.Equality:
2050                                 opcode = OpCodes.Ceq;
2051                                 break;
2052
2053                         case Operator.Inequality:
2054                                 ec.ig.Emit (OpCodes.Ceq);
2055                                 ec.ig.Emit (OpCodes.Ldc_I4_0);
2056
2057                                 opcode = OpCodes.Ceq;
2058                                 break;
2059
2060                         case Operator.LessThan:
2061                                 opcode = OpCodes.Clt;
2062                                 break;
2063
2064                         case Operator.GreaterThan:
2065                                 opcode = OpCodes.Cgt;
2066                                 break;
2067
2068                         case Operator.LessThanOrEqual:
2069                                 ec.ig.Emit (OpCodes.Cgt);
2070                                 ec.ig.Emit (OpCodes.Ldc_I4_0);
2071
2072                                 opcode = OpCodes.Ceq;
2073                                 break;
2074
2075                         case Operator.GreaterThanOrEqual:
2076                                 ec.ig.Emit (OpCodes.Clt);
2077                                 ec.ig.Emit (OpCodes.Ldc_I4_1);
2078
2079                                 opcode = OpCodes.Sub;
2080                                 break;
2081
2082                         case Operator.LogicalOr:
2083                         case Operator.BitwiseOr:
2084                                 opcode = OpCodes.Or;
2085                                 break;
2086
2087                         case Operator.LogicalAnd:
2088                         case Operator.BitwiseAnd:
2089                                 opcode = OpCodes.And;
2090                                 break;
2091
2092                         case Operator.ExclusiveOr:
2093                                 opcode = OpCodes.Xor;
2094                                 break;
2095
2096                         default:
2097                                 throw new Exception ("This should not happen: Operator = "
2098                                                      + oper.ToString ());
2099                         }
2100
2101                         ig.Emit (opcode);
2102                 }
2103         }
2104
2105         public class Conditional : Expression {
2106                 Expression expr, trueExpr, falseExpr;
2107
2108                 public Conditional (Expression expr, Expression trueExpr, Expression falseExpr)
2109                 {
2110                         this.expr = expr;
2111                         this.trueExpr = trueExpr;
2112                         this.falseExpr = falseExpr;
2113                 }
2114
2115                 public Expression Expr {
2116                         get {
2117                                 return expr;
2118                         }
2119                 }
2120
2121                 public Expression TrueExpr {
2122                         get {
2123                                 return trueExpr;
2124                         }
2125                 }
2126
2127                 public Expression FalseExpr {
2128                         get {
2129                                 return falseExpr;
2130                         }
2131                 }
2132
2133                 public override Expression Resolve (TypeContainer tc)
2134                 {
2135                         // FIXME: Implement;
2136                         throw new Exception ("Unimplemented");
2137                         // return this;
2138                 }
2139
2140                 public override void Emit (EmitContext ec)
2141                 {
2142                 }
2143         }
2144
2145         public class SimpleName : Expression {
2146                 public readonly string Name;
2147                 public readonly Location Location;
2148
2149                 public SimpleName (string name, Location l)
2150                 {
2151                         Name = name;
2152                         Location = l;
2153                 }
2154
2155                 //
2156                 // Checks whether we are trying to access an instance
2157                 // property, method or field from a static body.
2158                 //
2159                 Expression MemberStaticCheck (Report r, Expression e)
2160                 {
2161                         if (e is FieldExpr){
2162                                 FieldInfo fi = ((FieldExpr) e).FieldInfo;
2163
2164                                 if (!fi.IsStatic){
2165                                         r.Error (120,
2166                                                  "An object reference is required " +
2167                                                  "for the non-static field `"+Name+"'");
2168                                         return null;
2169                                 }
2170                         } else if (e is MethodGroupExpr){
2171                                 // FIXME: Pending reorganization of MemberLookup
2172                                 // Basically at this point we should have the
2173                                 // best match already selected for us, and
2174                                 // we should only have to check a *single*
2175                                 // Method for its static on/off bit.
2176                                 return e;
2177                         } else if (e is PropertyExpr){
2178                                 if (!((PropertyExpr) e).IsStatic){
2179                                         r.Error (120,
2180                                                  "An object reference is required " +
2181                                                  "for the non-static property access `"+
2182                                                  Name+"'");
2183                                         return null;
2184                                 }
2185                         }
2186
2187                         return e;
2188                 }
2189
2190                 //
2191                 // 7.5.2: Simple Names.
2192                 //
2193                 // Local Variables and Parameters are handled at
2194                 // parse time, so they never occur as SimpleNames.
2195                 //
2196                 Expression ResolveSimpleName (TypeContainer tc)
2197                 {
2198                         Expression e;
2199                         Report r = tc.RootContext.Report;
2200
2201                         e = MemberLookup (tc, tc.TypeBuilder, Name, true);
2202                         if (e != null){
2203                                 if (e is TypeExpr)
2204                                         return e;
2205                                 else if (e is FieldExpr){
2206                                         FieldExpr fe = (FieldExpr) e;
2207
2208                                         if (!fe.FieldInfo.IsStatic)
2209                                                 fe.Instance = new This ();
2210                                 }
2211
2212                                 if ((tc.ModFlags & Modifiers.STATIC) != 0)
2213                                         return MemberStaticCheck (r, e);
2214                                 else
2215                                         return e;
2216                         }
2217
2218                         //
2219                         // Do step 3 of the Simple Name resolution.
2220                         //
2221                         // FIXME: implement me.
2222
2223                         Error (tc, 103, Location, "The name `" + Name + "' does not exist in the class `" +
2224                                tc.Name + "'");
2225
2226                         return null;
2227                 }
2228
2229                 //
2230                 // SimpleName needs to handle a multitude of cases:
2231                 //
2232                 // simple_names and qualified_identifiers are placed on
2233                 // the tree equally.
2234                 //
2235                 public override Expression Resolve (TypeContainer tc)
2236                 {
2237                         if (Name.IndexOf (".") != -1)
2238                                 return ResolveMemberAccess (tc, Name);
2239                         else
2240                                 return ResolveSimpleName (tc);
2241                 }
2242
2243                 public override void Emit (EmitContext ec)
2244                 {
2245                         throw new Exception ("SimpleNames should be gone from the tree");
2246                 }
2247         }
2248
2249         // <summary>
2250         //   A simple interface that should be implemeneted by LValues
2251         // </summary>
2252         public interface LValue {
2253
2254                 // <summary>
2255                 //   The Store method should store the contents of the top
2256                 //   of the stack into the storage that is implemented by
2257                 //   the particular implementation of LValue
2258                 // </summary>
2259                 void Store     (EmitContext ec);
2260
2261                 // <summary>
2262                 //   The AddressOf method should generate code that loads
2263                 //   the address of the LValue and leaves it on the stack
2264                 // </summary>
2265                 void AddressOf (EmitContext ec);
2266         }
2267
2268         public class LocalVariableReference : Expression, LValue {
2269                 public readonly string Name;
2270                 public readonly Block Block;
2271
2272                 public LocalVariableReference (Block block, string name)
2273                 {
2274                         Block = block;
2275                         Name = name;
2276                         eclass = ExprClass.Variable;
2277                 }
2278
2279                 public VariableInfo VariableInfo {
2280                         get {
2281                                 return Block.GetVariableInfo (Name);
2282                         }
2283                 }
2284
2285                 public override Expression Resolve (TypeContainer tc)
2286                 {
2287                         VariableInfo vi = Block.GetVariableInfo (Name);
2288
2289                         type = vi.VariableType;
2290                         return this;
2291                 }
2292
2293                 public override void Emit (EmitContext ec)
2294                 {
2295                         VariableInfo vi = VariableInfo;
2296                         ILGenerator ig = ec.ig;
2297                         int idx = vi.Idx;
2298
2299                         switch (idx){
2300                         case 0:
2301                                 ig.Emit (OpCodes.Ldloc_0);
2302                                 break;
2303
2304                         case 1:
2305                                 ig.Emit (OpCodes.Ldloc_1);
2306                                 break;
2307
2308                         case 2:
2309                                 ig.Emit (OpCodes.Ldloc_2);
2310                                 break;
2311
2312                         case 3:
2313                                 ig.Emit (OpCodes.Ldloc_3);
2314                                 break;
2315
2316                         default:
2317                                 if (idx <= 255)
2318                                         ig.Emit (OpCodes.Ldloc_S, (byte) idx);
2319                                 else
2320                                         ig.Emit (OpCodes.Ldloc, idx);
2321                                 break;
2322                         }
2323                 }
2324
2325                 public void Store (EmitContext ec)
2326                 {
2327                         ILGenerator ig = ec.ig;
2328                         VariableInfo vi = VariableInfo;
2329                         int idx = vi.Idx;
2330
2331                         switch (idx){
2332                         case 0:
2333                                 ig.Emit (OpCodes.Stloc_0);
2334                                 break;
2335
2336                         case 1:
2337                                 ig.Emit (OpCodes.Stloc_1);
2338                                 break;
2339
2340                         case 2:
2341                                 ig.Emit (OpCodes.Stloc_2);
2342                                 break;
2343
2344                         case 3:
2345                                 ig.Emit (OpCodes.Stloc_3);
2346                                 break;
2347
2348                         default:
2349                                 if (idx <= 255)
2350                                         ig.Emit (OpCodes.Stloc_S, (byte) idx);
2351                                 else
2352                                         ig.Emit (OpCodes.Stloc, idx);
2353                                 break;
2354                         }
2355                 }
2356
2357                 public void AddressOf (EmitContext ec)
2358                 {
2359                         VariableInfo vi = VariableInfo;
2360                         int idx = vi.Idx;
2361
2362                         if (idx <= 255)
2363                                 ec.ig.Emit (OpCodes.Ldloca_S, (byte) idx);
2364                         else
2365                                 ec.ig.Emit (OpCodes.Ldloca, idx);
2366                 }
2367         }
2368
2369         public class ParameterReference : Expression, LValue {
2370                 public readonly Parameters Pars;
2371                 public readonly String Name;
2372                 public readonly int Idx;
2373
2374                 public ParameterReference (Parameters pars, int idx, string name)
2375                 {
2376                         Pars = pars;
2377                         Idx  = idx;
2378                         Name = name;
2379                         eclass = ExprClass.Variable;
2380                 }
2381
2382                 public override Expression Resolve (TypeContainer tc)
2383                 {
2384                         Type [] types = Pars.GetParameterInfo (tc);
2385
2386                         type = types [Idx];
2387
2388                         return this;
2389                 }
2390
2391                 public override void Emit (EmitContext ec)
2392                 {
2393                         if (Idx <= 255)
2394                                 ec.ig.Emit (OpCodes.Ldarg_S, (byte) Idx);
2395                         else
2396                                 ec.ig.Emit (OpCodes.Ldarg, Idx);
2397                 }
2398
2399                 public void Store (EmitContext ec)
2400                 {
2401                         if (Idx <= 255)
2402                                 ec.ig.Emit (OpCodes.Starg_S, (byte) Idx);
2403                         else
2404                                 ec.ig.Emit (OpCodes.Starg, Idx);
2405
2406                 }
2407
2408                 public void AddressOf (EmitContext ec)
2409                 {
2410                         if (Idx <= 255)
2411                                 ec.ig.Emit (OpCodes.Ldarga_S, (byte) Idx);
2412                         else
2413                                 ec.ig.Emit (OpCodes.Ldarga, Idx);
2414                 }
2415         }
2416
2417         // <summary>
2418         //   Used for arguments to New(), Invocation()
2419         // </summary>
2420         public class Argument {
2421                 public enum AType {
2422                         Expression,
2423                         Ref,
2424                         Out
2425                 };
2426
2427                 public readonly AType Type;
2428                 Expression expr;
2429
2430                 public Argument (Expression expr, AType type)
2431                 {
2432                         this.expr = expr;
2433                         this.Type = type;
2434                 }
2435
2436                 public Expression Expr {
2437                         get {
2438                                 return expr;
2439                         }
2440
2441                         set {
2442                                 expr = value;
2443                         }
2444                 }
2445
2446                 public bool Resolve (TypeContainer tc)
2447                 {
2448                         expr = expr.Resolve (tc);
2449
2450                         return expr != null;
2451                 }
2452
2453                 public void Emit (EmitContext ec)
2454                 {
2455                         expr.Emit (ec);
2456                 }
2457         }
2458
2459         // <summary>
2460         //   Invocation of methods or delegates.
2461         // </summary>
2462         public class Invocation : ExpressionStatement {
2463                 public readonly ArrayList Arguments;
2464                 public readonly Location Location;
2465
2466                 Expression expr;
2467                 MethodBase method = null;
2468
2469                 static Hashtable method_parameter_cache;
2470
2471                 static Invocation ()
2472                 {
2473                         method_parameter_cache = new Hashtable ();
2474                 }
2475
2476                 //
2477                 // arguments is an ArrayList, but we do not want to typecast,
2478                 // as it might be null.
2479                 //
2480                 // FIXME: only allow expr to be a method invocation or a
2481                 // delegate invocation (7.5.5)
2482                 //
2483                 public Invocation (Expression expr, ArrayList arguments, Location l)
2484                 {
2485                         this.expr = expr;
2486                         Arguments = arguments;
2487                         Location = l;
2488                 }
2489
2490                 public Expression Expr {
2491                         get {
2492                                 return expr;
2493                         }
2494                 }
2495
2496                 /// <summary>
2497                 ///   Computes whether Argument `a' and the Type t of the  ParameterInfo `pi' are
2498                 ///   compatible, and if so, how good is the match (in terms of
2499                 ///   "better conversions" (7.4.2.3).
2500                 ///
2501                 ///   0   is the best possible match.
2502                 ///   -1  represents a type mismatch.
2503                 ///   -2  represents a ref/out mismatch.
2504                 /// </summary>
2505                 static int Badness (Argument a, Type t)
2506                 {
2507                         Expression argument_expr = a.Expr;
2508                         Type argument_type = argument_expr.Type;
2509
2510                         if (argument_type == null){
2511                                 throw new Exception ("Expression of type " + a.Expr + " does not resolve its type");
2512                         }
2513
2514                         if (t == argument_type)
2515                                 return 0;
2516
2517                         //
2518                         // Now probe whether an implicit constant expression conversion
2519                         // can be used.
2520                         //
2521                         // An implicit constant expression conversion permits the following
2522                         // conversions:
2523                         //
2524                         //    * A constant-expression of type `int' can be converted to type
2525                         //      sbyte, byute, short, ushort, uint, ulong provided the value of
2526                         //      of the expression is withing the range of the destination type.
2527                         //
2528                         //    * A constant-expression of type long can be converted to type
2529                         //      ulong, provided the value of the constant expression is not negative
2530                         //
2531                         // FIXME: Note that this assumes that constant folding has
2532                         // taken place.  We dont do constant folding yet.
2533                         //
2534
2535                         if (argument_type == TypeManager.int32_type && argument_expr is IntLiteral){
2536                                 IntLiteral ei = (IntLiteral) argument_expr;
2537                                 int value = ei.Value;
2538
2539                                 if (t == TypeManager.sbyte_type){
2540                                         if (value >= SByte.MinValue && value <= SByte.MaxValue)
2541                                                 return 1;
2542                                 } else if (t == TypeManager.byte_type){
2543                                         if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
2544                                                 return 1;
2545                                 } else if (t == TypeManager.short_type){
2546                                         if (value >= Int16.MinValue && value <= Int16.MaxValue)
2547                                                 return 1;
2548                                 } else if (t == TypeManager.ushort_type){
2549                                         if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
2550                                                 return 1;
2551                                 } else if (t == TypeManager.uint32_type){
2552                                         //
2553                                         // we can optimize this case: a positive int32
2554                                         // always fits on a uint32
2555                                         //
2556                                         if (value >= 0)
2557                                                 return 1;
2558                                 } else if (t == TypeManager.uint64_type){
2559                                         //
2560                                         // we can optimize this case: a positive int32
2561                                         // always fits on a uint64
2562                                         //
2563                                         if (value >= 0)
2564                                                 return 1;
2565                                 }
2566                         } else if (argument_type == TypeManager.int64_type && argument_expr is LongLiteral){
2567                                 LongLiteral ll = (LongLiteral) argument_expr;
2568
2569                                 if (t == TypeManager.uint64_type)
2570                                         if (ll.Value > 0)
2571                                                 return 1;
2572                         }
2573
2574                         // FIXME: Implement user-defined implicit conversions here.
2575                         // FIXME: Implement better conversion here.
2576
2577                         return -1;
2578                 }
2579
2580                 // <summary>
2581                 //   Returns the Parameters (a ParameterData interface) for the
2582                 //   Method `mb'
2583                 // </summary>
2584                 static ParameterData GetParameterData (MethodBase mb)
2585                 {
2586                         object pd = method_parameter_cache [mb];
2587
2588                         if (pd != null)
2589                                 return (ParameterData) pd;
2590
2591                         if (mb is MethodBuilder || mb is ConstructorBuilder){
2592                                 MethodCore mc = TypeContainer.LookupMethodByBuilder (mb);
2593
2594                                 InternalParameters ip = mc.ParameterInfo;
2595                                 method_parameter_cache [mb] = ip;
2596
2597                                 return (ParameterData) ip;
2598                         } else {
2599                                 ParameterInfo [] pi = mb.GetParameters ();
2600                                 ReflectionParameters rp = new ReflectionParameters (pi);
2601                                 method_parameter_cache [mb] = rp;
2602
2603                                 return (ParameterData) rp;
2604                         }
2605                 }
2606
2607                 static bool ConversionExists (TypeContainer tc, Type from, Type to)
2608                 {
2609                         // Locate user-defined implicit operators
2610
2611                         Expression mg;
2612
2613                         mg = MemberLookup (tc, to, "op_Implicit", false);
2614
2615                         if (mg != null) {
2616                                 MethodGroupExpr me = (MethodGroupExpr) mg;
2617
2618                                 for (int i = me.Methods.Length; i > 0;) {
2619                                         i--;
2620                                         MethodBase mb = me.Methods [i];
2621                                         ParameterData pd = GetParameterData (mb);
2622
2623                                         if (from == pd.ParameterType (0))
2624                                                 return true;
2625                                 }
2626                         }
2627
2628                         mg = MemberLookup (tc, from, "op_Implicit", false);
2629
2630                         if (mg != null) {
2631                                 MethodGroupExpr me = (MethodGroupExpr) mg;
2632
2633                                 for (int i = me.Methods.Length; i > 0;) {
2634                                         i--;
2635                                         MethodBase mb = me.Methods [i];
2636                                         MethodInfo mi = (MethodInfo) mb;
2637
2638                                         if (mi.ReturnType == to)
2639                                                 return true;
2640                                 }
2641                         }
2642
2643                         return false;
2644                 }
2645
2646                 // <summary>
2647                 //  Determines "better conversion" as specified in 7.4.2.3
2648                 //  Returns : 1 if a->p is better
2649                 //            0 if a->q or neither is better
2650                 // </summary>
2651                 static int BetterConversion (TypeContainer tc, Argument a, Type p, Type q)
2652                 {
2653
2654                         Type argument_type = a.Expr.Type;
2655                         Expression argument_expr = a.Expr;
2656
2657                         if (argument_type == null)
2658                                 throw new Exception ("Expression of type " + a.Expr + " does not resolve its type");
2659
2660                         if (p == q)
2661                                 return 0;
2662
2663                         if (argument_type == p)
2664                                 return 1;
2665
2666                         if (argument_type == q)
2667                                 return 0;
2668
2669                         //
2670                         // Now probe whether an implicit constant expression conversion
2671                         // can be used.
2672                         //
2673                         // An implicit constant expression conversion permits the following
2674                         // conversions:
2675                         //
2676                         //    * A constant-expression of type `int' can be converted to type
2677                         //      sbyte, byute, short, ushort, uint, ulong provided the value of
2678                         //      of the expression is withing the range of the destination type.
2679                         //
2680                         //    * A constant-expression of type long can be converted to type
2681                         //      ulong, provided the value of the constant expression is not negative
2682                         //
2683                         // FIXME: Note that this assumes that constant folding has
2684                         // taken place.  We dont do constant folding yet.
2685                         //
2686
2687                         if (argument_type == TypeManager.int32_type && argument_expr is IntLiteral){
2688                                 IntLiteral ei = (IntLiteral) argument_expr;
2689                                 int value = ei.Value;
2690
2691                                 if (p == TypeManager.sbyte_type){
2692                                         if (value >= SByte.MinValue && value <= SByte.MaxValue)
2693                                                 return 1;
2694                                 } else if (p == TypeManager.byte_type){
2695                                         if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
2696                                                 return 1;
2697                                 } else if (p == TypeManager.short_type){
2698                                         if (value >= Int16.MinValue && value <= Int16.MaxValue)
2699                                                 return 1;
2700                                 } else if (p == TypeManager.ushort_type){
2701                                         if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
2702                                                 return 1;
2703                                 } else if (p == TypeManager.uint32_type){
2704                                         //
2705                                         // we can optimize this case: a positive int32
2706                                         // always fits on a uint32
2707                                         //
2708                                         if (value >= 0)
2709                                                 return 1;
2710                                 } else if (p == TypeManager.uint64_type){
2711                                         //
2712                                         // we can optimize this case: a positive int32
2713                                         // always fits on a uint64
2714                                         //
2715                                         if (value >= 0)
2716                                                 return 1;
2717                                 }
2718                         } else if (argument_type == TypeManager.int64_type && argument_expr is LongLiteral){
2719                                 LongLiteral ll = (LongLiteral) argument_expr;
2720
2721                                 if (p == TypeManager.uint64_type){
2722                                         if (ll.Value > 0)
2723                                                 return 1;
2724                                 }
2725                         }
2726
2727                         if (q == null) {
2728
2729                                 Expression tmp;
2730
2731                                 tmp = ConvertImplicit (tc, argument_expr, p);
2732
2733                                 if (tmp != null)
2734                                         return 1;
2735                                 else
2736                                         return 0;
2737
2738                         }
2739
2740                         if (ConversionExists (tc, p, q) == true &&
2741                             ConversionExists (tc, q, p) == false)
2742                                 return 1;
2743
2744                         if (p == TypeManager.sbyte_type)
2745                                 if (q == TypeManager.byte_type || q == TypeManager.ushort_type ||
2746                                     q == TypeManager.uint32_type || q == TypeManager.uint64_type)
2747                                         return 1;
2748
2749                         if (p == TypeManager.short_type)
2750                                 if (q == TypeManager.ushort_type || q == TypeManager.uint32_type ||
2751                                     q == TypeManager.uint64_type)
2752                                         return 1;
2753
2754                         if (p == TypeManager.int32_type)
2755                                 if (q == TypeManager.uint32_type || q == TypeManager.uint64_type)
2756                                         return 1;
2757
2758                         if (p == TypeManager.int64_type)
2759                                 if (q == TypeManager.uint64_type)
2760                                         return 1;
2761
2762                         return 0;
2763                 }
2764
2765                 // <summary>
2766                 //  Determines "Better function" and returns an integer indicating :
2767                 //  0 if candidate ain't better
2768                 //  1 if candidate is better than the current best match
2769                 // </summary>
2770                 static int BetterFunction (TypeContainer tc, ArrayList args, MethodBase candidate, MethodBase best)
2771                 {
2772                         ParameterData candidate_pd = GetParameterData (candidate);
2773                         ParameterData best_pd;
2774                         int argument_count;
2775
2776                         if (args == null)
2777                                 argument_count = 0;
2778                         else
2779                                 argument_count = args.Count;
2780
2781                         if (candidate_pd.Count == 0 && argument_count == 0)
2782                                 return 1;
2783
2784                         if (best == null) {
2785                                 if (candidate_pd.Count == argument_count) {
2786                                         int x = 0;
2787                                         for (int j = argument_count; j > 0;) {
2788                                                 j--;
2789
2790                                                 Argument a = (Argument) args [j];
2791
2792                                                 x = BetterConversion (tc, a, candidate_pd.ParameterType (j), null);
2793
2794                                                 if (x > 0)
2795                                                         continue;
2796                                                 else
2797                                                         break;
2798                                         }
2799
2800                                         if (x > 0)
2801                                                 return 1;
2802                                         else
2803                                                 return 0;
2804
2805                                 } else
2806                                         return 0;
2807                         }
2808
2809                         best_pd = GetParameterData (best);
2810
2811                         if (candidate_pd.Count == argument_count && best_pd.Count == argument_count) {
2812                                 int rating1 = 0, rating2 = 0;
2813
2814                                 for (int j = argument_count; j > 0;) {
2815                                         j--;
2816                                         int x, y;
2817
2818                                         Argument a = (Argument) args [j];
2819
2820                                         x = BetterConversion (tc, a, candidate_pd.ParameterType (j),
2821                                                               best_pd.ParameterType (j));
2822                                         y = BetterConversion (tc, a, best_pd.ParameterType (j),
2823                                                               candidate_pd.ParameterType (j));
2824
2825                                         rating1 += x;
2826                                         rating2 += y;
2827                                 }
2828
2829                                 if (rating1 > rating2)
2830                                         return 1;
2831                                 else
2832                                         return 0;
2833                         } else
2834                                 return 0;
2835
2836                 }
2837
2838                 public static string FullMethodDesc (MethodBase mb)
2839                 {
2840                         StringBuilder sb = new StringBuilder (mb.Name);
2841                         ParameterData pd = GetParameterData (mb);
2842
2843                         sb.Append (" (");
2844                         for (int i = pd.Count; i > 0;) {
2845                                 i--;
2846                                 sb.Append (TypeManager.CSharpName (pd.ParameterType (i)));
2847                                 if (i != 0)
2848                                         sb.Append (",");
2849                         }
2850
2851                         sb.Append (")");
2852                         return sb.ToString ();
2853                 }
2854
2855                 public static MethodGroupExpr MakeUnionSet (Expression mg1, Expression mg2)
2856                 {
2857
2858                         if (mg1 != null || mg2 != null) {
2859
2860                                 MethodGroupExpr left_set = null, right_set = null;
2861                                 int length1 = 0, length2 = 0;
2862
2863                                 if (mg1 != null) {
2864                                         left_set = (MethodGroupExpr) mg1;
2865                                         length1 = left_set.Methods.Length;
2866                                 }
2867
2868                                 if (mg2 != null) {
2869                                         right_set = (MethodGroupExpr) mg2;
2870                                         length2 = right_set.Methods.Length;
2871                                 }
2872
2873                                 MemberInfo [] miset = new MemberInfo [length1 + length2];
2874                                 if (left_set != null)
2875                                         left_set.Methods.CopyTo (miset, 0);
2876                                 if (right_set != null)
2877                                         right_set.Methods.CopyTo (miset, length1);
2878
2879                                 MethodGroupExpr union = new MethodGroupExpr (miset);
2880
2881                                 return union;
2882
2883                         }
2884
2885                         return null;
2886
2887                 }
2888
2889                 // <summary>
2890                 //   Find the Applicable Function Members (7.4.2.1)
2891                 //
2892                 //   me: Method Group expression with the members to select.
2893                 //       it might contain constructors or methods (or anything
2894                 //       that maps to a method).
2895                 //
2896                 //   Arguments: ArrayList containing resolved Argument objects.
2897                 //
2898                 //   Returns: The MethodBase (either a ConstructorInfo or a MethodInfo)
2899                 //            that is the best match of me on Arguments.
2900                 //
2901                 // </summary>
2902                 public static MethodBase OverloadResolve (TypeContainer tc, MethodGroupExpr me,
2903                                                           ArrayList Arguments, Location loc)
2904                 {
2905                         ArrayList afm = new ArrayList ();
2906                         int best_match_idx = -1;
2907                         MethodBase method = null;
2908                         int argument_count;
2909
2910                         for (int i = me.Methods.Length; i > 0; ){
2911                                 i--;
2912                                 MethodBase candidate  = me.Methods [i];
2913                                 int x;
2914
2915                                 x = BetterFunction (tc, Arguments, candidate, method);
2916
2917                                 if (x == 0)
2918                                         continue;
2919                                 else {
2920                                         best_match_idx = i;
2921                                         method = me.Methods [best_match_idx];
2922                                 }
2923                         }
2924
2925                         if (Arguments == null)
2926                                 argument_count = 0;
2927                         else
2928                                 argument_count = Arguments.Count;
2929
2930                         ParameterData pd;
2931
2932                         // Now we see if we can at least find a method with the same number of arguments
2933                         // and then try doing implicit conversion on the arguments
2934                         if (best_match_idx == -1) {
2935
2936                                 for (int i = me.Methods.Length; i > 0;) {
2937                                         i--;
2938                                         MethodBase mb = me.Methods [i];
2939                                         pd = GetParameterData (mb);
2940
2941                                         if (pd.Count == argument_count) {
2942                                                 best_match_idx = i;
2943                                                 method = me.Methods [best_match_idx];
2944                                                 break;
2945                                         } else
2946                                                 continue;
2947                                 }
2948
2949                         }
2950
2951                         if (method == null)
2952                                 return null;
2953
2954                         // And now convert implicitly, each argument to the required type
2955
2956                         pd = GetParameterData (method);
2957
2958                         for (int j = argument_count; j > 0;) {
2959                                 j--;
2960                                 Argument a = (Argument) Arguments [j];
2961                                 Expression a_expr = a.Expr;
2962
2963                                 Expression conv = ConvertImplicit (tc, a_expr, pd.ParameterType (j));
2964
2965                                 if (conv == null) {
2966                                         Error (tc, 1502, loc,
2967                                                "The best overloaded match for method '" + FullMethodDesc (method) +
2968                                                "' has some invalid arguments");
2969                                         Error (tc, 1503, loc,
2970                                                "Argument " + (j+1) +
2971                                                " : Cannot convert from '" + TypeManager.CSharpName (a_expr.Type)
2972                                                + "' to '" + TypeManager.CSharpName (pd.ParameterType (j)) + "'");
2973                                         return null;
2974                                 }
2975
2976                                 //
2977                                 // Update the argument with the implicit conversion
2978                                 //
2979                                 if (a_expr != conv)
2980                                         a.Expr = conv;
2981                         }
2982
2983                         return method;
2984                 }
2985
2986
2987                 public override Expression Resolve (TypeContainer tc)
2988                 {
2989                         //
2990                         // First, resolve the expression that is used to
2991                         // trigger the invocation
2992                         //
2993                         this.expr = expr.Resolve (tc);
2994                         if (this.expr == null)
2995                                 return null;
2996
2997                         if (!(this.expr is MethodGroupExpr)){
2998                                 report118 (tc, this.expr, "method group");
2999                                 return null;
3000                         }
3001
3002                         //
3003                         // Next, evaluate all the expressions in the argument list
3004                         //
3005                         if (Arguments != null){
3006                                 for (int i = Arguments.Count; i > 0;){
3007                                         --i;
3008                                         Argument a = (Argument) Arguments [i];
3009
3010                                         if (!a.Resolve (tc))
3011                                                 return null;
3012                                 }
3013                         }
3014
3015                         method = OverloadResolve (tc, (MethodGroupExpr) this.expr, Arguments, Location);
3016
3017                         if (method == null){
3018                                 Error (tc, -6, Location,
3019                                        "Could not find any applicable function for this argument list");
3020                                 return null;
3021                         }
3022
3023                         if (method is MethodInfo)
3024                                 type = ((MethodInfo)method).ReturnType;
3025
3026                         return this;
3027                 }
3028
3029                 public static void EmitArguments (EmitContext ec, MethodBase method, ArrayList Arguments)
3030                 {
3031                         int top;
3032
3033                         if (Arguments != null)
3034                                 top = Arguments.Count;
3035                         else
3036                                 top = 0;
3037
3038                         for (int i = 0; i < top; i++){
3039                                 Argument a = (Argument) Arguments [i];
3040
3041                                 a.Emit (ec);
3042                         }
3043                 }
3044
3045                 public override void Emit (EmitContext ec)
3046                 {
3047                         bool is_static = method.IsStatic;
3048
3049                         if (!is_static){
3050                                 MethodGroupExpr mg = (MethodGroupExpr) this.expr;
3051
3052                                 //
3053                                 // If this is ourselves, push "this"
3054                                 //
3055                                 if (mg.InstanceExpression == null){
3056                                         ec.ig.Emit (OpCodes.Ldarg_0);
3057                                 } else {
3058                                         //
3059                                         // Push the instance expression
3060                                         //
3061                                         mg.InstanceExpression.Emit (ec);
3062                                 }
3063                         }
3064
3065                         if (Arguments != null)
3066                                 EmitArguments (ec, method, Arguments);
3067
3068                         if (is_static){
3069                                 if (method is MethodInfo)
3070                                         ec.ig.Emit (OpCodes.Call, (MethodInfo) method);
3071                                 else
3072                                         ec.ig.Emit (OpCodes.Call, (ConstructorInfo) method);
3073                         } else {
3074                                 if (method is MethodInfo)
3075                                         ec.ig.Emit (OpCodes.Callvirt, (MethodInfo) method);
3076                                 else
3077                                         ec.ig.Emit (OpCodes.Callvirt, (ConstructorInfo) method);
3078                         }
3079                 }
3080
3081                 public override void EmitStatement (EmitContext ec)
3082                 {
3083                         Emit (ec);
3084
3085                         //
3086                         // Pop the return value if there is one
3087                         //
3088                         if (method is MethodInfo){
3089                                 if (((MethodInfo)method).ReturnType != TypeManager.void_type)
3090                                         ec.ig.Emit (OpCodes.Pop);
3091                         }
3092                 }
3093         }
3094
3095         public class New : ExpressionStatement {
3096
3097                 public enum NType {
3098                         Object,
3099                         Array
3100                 };
3101
3102                 public readonly NType     NewType;
3103                 public readonly ArrayList Arguments;
3104                 public readonly string    RequestedType;
3105                 // These are for the case when we have an array
3106                 public readonly string    Rank;
3107                 public readonly ArrayList Indices;
3108                 public readonly ArrayList Initializers;
3109
3110                 Location Location;
3111                 MethodBase method = null;
3112
3113                 public New (string requested_type, ArrayList arguments, Location loc)
3114                 {
3115                         RequestedType = requested_type;
3116                         Arguments = arguments;
3117                         NewType = NType.Object;
3118                         Location = loc;
3119                 }
3120
3121                 public New (string requested_type, ArrayList exprs, string rank, ArrayList initializers, Location loc)
3122                 {
3123                         RequestedType = requested_type;
3124                         Indices       = exprs;
3125                         Rank          = rank;
3126                         Initializers  = initializers;
3127                         NewType       = NType.Array;
3128                         Location      = loc;
3129                 }
3130
3131                 public override Expression Resolve (TypeContainer tc)
3132                 {
3133                         type = tc.LookupType (RequestedType, false);
3134
3135                         if (type == null)
3136                                 return null;
3137
3138                         Expression ml;
3139
3140                         ml = MemberLookup (tc, type, ".ctor", false,
3141                                            MemberTypes.Constructor, AllBindingsFlags);
3142
3143                         if (! (ml is MethodGroupExpr)){
3144                                 //
3145                                 // FIXME: Find proper error
3146                                 //
3147                                 report118 (tc, ml, "method group");
3148                                 return null;
3149                         }
3150
3151                         if (Arguments != null){
3152                                 for (int i = Arguments.Count; i > 0;){
3153                                         --i;
3154                                         Argument a = (Argument) Arguments [i];
3155
3156                                         if (!a.Resolve (tc))
3157                                                 return null;
3158                                 }
3159                         }
3160
3161                         method = Invocation.OverloadResolve (tc, (MethodGroupExpr) ml, Arguments, Location);
3162
3163                         if (method == null) {
3164                                 Error (tc, -6, Location,
3165                                        "New invocation: Can not find a constructor for this argument list");
3166                                 return null;
3167                         }
3168
3169                         return this;
3170                 }
3171
3172                 public override void Emit (EmitContext ec)
3173                 {
3174                         Invocation.EmitArguments (ec, method, Arguments);
3175                         ec.ig.Emit (OpCodes.Newobj, (ConstructorInfo) method);
3176                 }
3177
3178                 public override void EmitStatement (EmitContext ec)
3179                 {
3180                         Emit (ec);
3181                         ec.ig.Emit (OpCodes.Pop);
3182                 }
3183         }
3184
3185         //
3186         // Represents the `this' construct
3187         //
3188         public class This : Expression, LValue {
3189                 public override Expression Resolve (TypeContainer tc)
3190                 {
3191                         eclass = ExprClass.Variable;
3192                         type = tc.TypeBuilder;
3193
3194                         //
3195                         // FIXME: Verify that this is only used in instance contexts.
3196                         //
3197                         return this;
3198                 }
3199
3200                 public override void Emit (EmitContext ec)
3201                 {
3202                         ec.ig.Emit (OpCodes.Ldarg_0);
3203                 }
3204
3205                 public void Store (EmitContext ec)
3206                 {
3207                         //
3208                         // Assignment to the "this" variable.
3209                         //
3210                         // FIXME: Apparently this is a bug that we
3211                         // must catch as `this' seems to be readonly ;-)
3212                         //
3213                         ec.ig.Emit (OpCodes.Starg, 0);
3214                 }
3215
3216                 public void AddressOf (EmitContext ec)
3217                 {
3218                         ec.ig.Emit (OpCodes.Ldarga_S, (byte) 0);
3219                 }
3220         }
3221
3222         public class TypeOf : Expression {
3223                 public readonly string QueriedType;
3224
3225                 public TypeOf (string queried_type)
3226                 {
3227                         QueriedType = queried_type;
3228                 }
3229
3230                 public override Expression Resolve (TypeContainer tc)
3231                 {
3232                         type = tc.LookupType (QueriedType, false);
3233
3234                         if (type == null)
3235                                 return null;
3236
3237                         eclass = ExprClass.Type;
3238                         return this;
3239                 }
3240
3241                 public override void Emit (EmitContext ec)
3242                 {
3243                         throw new Exception ("Implement me");
3244                         // FIXME: Implement.
3245                 }
3246         }
3247
3248         public class SizeOf : Expression {
3249                 public readonly string QueriedType;
3250
3251                 public SizeOf (string queried_type)
3252                 {
3253                         this.QueriedType = queried_type;
3254                 }
3255
3256                 public override Expression Resolve (TypeContainer tc)
3257                 {
3258                         // FIXME: Implement;
3259                         throw new Exception ("Unimplemented");
3260                         // return this;
3261                 }
3262
3263                 public override void Emit (EmitContext ec)
3264                 {
3265                         throw new Exception ("Implement me");
3266                 }
3267         }
3268
3269         public class MemberAccess : Expression {
3270                 public readonly string Identifier;
3271                 Expression expr;
3272                 Expression member_lookup;
3273
3274                 public MemberAccess (Expression expr, string id)
3275                 {
3276                         this.expr = expr;
3277                         Identifier = id;
3278                 }
3279
3280                 public Expression Expr {
3281                         get {
3282                                 return expr;
3283                         }
3284                 }
3285
3286                 public override Expression Resolve (TypeContainer tc)
3287                 {
3288                         Expression new_expression = expr.Resolve (tc);
3289
3290                         if (new_expression == null)
3291                                 return null;
3292
3293                         member_lookup = MemberLookup (tc, expr.Type, Identifier, false);
3294
3295                         if (member_lookup is MethodGroupExpr){
3296                                 MethodGroupExpr mg = (MethodGroupExpr) member_lookup;
3297
3298                                 //
3299                                 // Bind the instance expression to it
3300                                 //
3301                                 // FIXME: This is a horrible way of detecting if it is
3302                                 // an instance expression.  Figure out how to fix this.
3303                                 //
3304
3305                                 if (expr is LocalVariableReference ||
3306                                     expr is ParameterReference ||
3307                                     expr is FieldExpr)
3308                                         mg.InstanceExpression = expr;
3309
3310                                 return member_lookup;
3311                         } else if (member_lookup is FieldExpr){
3312                                 FieldExpr fe = (FieldExpr) member_lookup;
3313
3314                                 fe.Instance = expr;
3315
3316                                 return member_lookup;
3317                         } else
3318                                 //
3319                                 // FIXME: This should generate the proper node
3320                                 // ie, for a Property Access, it should like call it
3321                                 // and stuff.
3322
3323                                 return member_lookup;
3324                 }
3325
3326                 public override void Emit (EmitContext ec)
3327                 {
3328                         throw new Exception ("Implement me");
3329                 }
3330
3331         }
3332
3333         // <summary>
3334         //   Nodes of type Namespace are created during the semantic
3335         //   analysis to resolve member_access/qualified_identifier/simple_name
3336         //   accesses.
3337         //
3338         //   They are born `resolved'.
3339         // </summary>
3340         public class NamespaceExpr : Expression {
3341                 public readonly string Name;
3342
3343                 public NamespaceExpr (string name)
3344                 {
3345                         Name = name;
3346                         eclass = ExprClass.Namespace;
3347                 }
3348
3349                 public override Expression Resolve (TypeContainer tc)
3350                 {
3351                         return this;
3352                 }
3353
3354                 public override void Emit (EmitContext ec)
3355                 {
3356                         throw new Exception ("Namespace expressions should never be emitted");
3357                 }
3358         }
3359
3360         // <summary>
3361         //   Fully resolved expression that evaluates to a type
3362         // </summary>
3363         public class TypeExpr : Expression {
3364                 public TypeExpr (Type t)
3365                 {
3366                         Type = t;
3367                         eclass = ExprClass.Type;
3368                 }
3369
3370                 override public Expression Resolve (TypeContainer tc)
3371                 {
3372                         return this;
3373                 }
3374
3375                 override public void Emit (EmitContext ec)
3376                 {
3377                         throw new Exception ("Implement me");
3378                 }
3379         }
3380
3381         // <summary>
3382         //   MethodGroup Expression.
3383         //
3384         //   This is a fully resolved expression that evaluates to a type
3385         // </summary>
3386         public class MethodGroupExpr : Expression {
3387                 public readonly MethodBase [] Methods;
3388                 Expression instance_expression = null;
3389
3390                 public MethodGroupExpr (MemberInfo [] mi)
3391                 {
3392                         Methods = new MethodBase [mi.Length];
3393                         mi.CopyTo (Methods, 0);
3394                         eclass = ExprClass.MethodGroup;
3395                 }
3396
3397                 //
3398                 // `A method group may have associated an instance expression'
3399                 //
3400                 public Expression InstanceExpression {
3401                         get {
3402                                 return instance_expression;
3403                         }
3404
3405                         set {
3406                                 instance_expression = value;
3407                         }
3408                 }
3409
3410                 override public Expression Resolve (TypeContainer tc)
3411                 {
3412                         return this;
3413                 }
3414
3415                 override public void Emit (EmitContext ec)
3416                 {
3417                         throw new Exception ("This should never be reached");
3418                 }
3419         }
3420
3421         //   Fully resolved expression that evaluates to a Field
3422         // </summary>
3423         public class FieldExpr : Expression, LValue {
3424                 public readonly FieldInfo FieldInfo;
3425                 public Expression Instance;
3426
3427                 public FieldExpr (FieldInfo fi)
3428                 {
3429                         FieldInfo = fi;
3430                         eclass = ExprClass.Variable;
3431                         type = fi.FieldType;
3432                 }
3433
3434                 override public Expression Resolve (TypeContainer tc)
3435                 {
3436                         if (!FieldInfo.IsStatic){
3437                                 if (Instance == null){
3438                                         throw new Exception ("non-static FieldExpr without instance var\n" +
3439                                                              "You have to assign the Instance variable\n" +
3440                                                              "Of the FieldExpr to set this\n");
3441                                 }
3442
3443                                 Instance = Instance.Resolve (tc);
3444                                 if (Instance == null)
3445                                         return null;
3446
3447                         }
3448                         return this;
3449                 }
3450
3451                 override public void Emit (EmitContext ec)
3452                 {
3453                         ILGenerator ig = ec.ig;
3454
3455                         if (FieldInfo.IsStatic)
3456                                 ig.Emit (OpCodes.Ldsfld, FieldInfo);
3457                         else {
3458                                 Instance.Emit (ec);
3459
3460                                 ig.Emit (OpCodes.Ldfld, FieldInfo);
3461                         }
3462                 }
3463
3464                 public void Store (EmitContext ec)
3465                 {
3466                         if (FieldInfo.IsStatic)
3467                                 ec.ig.Emit (OpCodes.Stsfld, FieldInfo);
3468                         else
3469                                 ec.ig.Emit (OpCodes.Stfld, FieldInfo);
3470                 }
3471
3472                 public void AddressOf (EmitContext ec)
3473                 {
3474                         if (FieldInfo.IsStatic)
3475                                 ec.ig.Emit (OpCodes.Ldsflda, FieldInfo);
3476                         else {
3477                                 Instance.Emit (ec);
3478                                 ec.ig.Emit (OpCodes.Ldflda, FieldInfo);
3479                         }
3480                 }
3481         }
3482
3483         // <summary>
3484         //   Fully resolved expression that evaluates to a Property
3485         // </summary>
3486         public class PropertyExpr : Expression {
3487                 public readonly PropertyInfo PropertyInfo;
3488                 public readonly bool IsStatic;
3489
3490                 public PropertyExpr (PropertyInfo pi)
3491                 {
3492                         PropertyInfo = pi;
3493                         eclass = ExprClass.PropertyAccess;
3494                         IsStatic = false;
3495
3496                         MethodBase [] acc = pi.GetAccessors ();
3497
3498                         for (int i = 0; i < acc.Length; i++)
3499                                 if (acc [i].IsStatic)
3500                                         IsStatic = true;
3501
3502                         type = pi.PropertyType;
3503                 }
3504
3505                 override public Expression Resolve (TypeContainer tc)
3506                 {
3507                         // We are born in resolved state.
3508                         return this;
3509                 }
3510
3511                 override public void Emit (EmitContext ec)
3512                 {
3513                         // FIXME: Implement;
3514                         throw new Exception ("Unimplemented");
3515                 }
3516         }
3517
3518         // <summary>
3519         //   Fully resolved expression that evaluates to a Expression
3520         // </summary>
3521         public class EventExpr : Expression {
3522                 public readonly EventInfo EventInfo;
3523
3524                 public EventExpr (EventInfo ei)
3525                 {
3526                         EventInfo = ei;
3527                         eclass = ExprClass.EventAccess;
3528                 }
3529
3530                 override public Expression Resolve (TypeContainer tc)
3531                 {
3532                         // We are born in resolved state.
3533                         return this;
3534                 }
3535
3536                 override public void Emit (EmitContext ec)
3537                 {
3538                         throw new Exception ("Implement me");
3539                         // FIXME: Implement.
3540                 }
3541         }
3542
3543         public class CheckedExpr : Expression {
3544
3545                 public Expression Expr;
3546
3547                 public CheckedExpr (Expression e)
3548                 {
3549                         Expr = e;
3550                 }
3551
3552                 public override Expression Resolve (TypeContainer tc)
3553                 {
3554                         Expr = Expr.Resolve (tc);
3555
3556                         if (Expr == null)
3557                                 return null;
3558
3559                         eclass = Expr.ExprClass;
3560                         type = Expr.Type;
3561                         return this;
3562                 }
3563
3564                 public override void Emit (EmitContext ec)
3565                 {
3566                         bool last_check = ec.CheckState;
3567
3568                         ec.CheckState = true;
3569                         Expr.Emit (ec);
3570                         ec.CheckState = last_check;
3571                 }
3572
3573         }
3574
3575         public class UnCheckedExpr : Expression {
3576
3577                 public Expression Expr;
3578
3579                 public UnCheckedExpr (Expression e)
3580                 {
3581                         Expr = e;
3582                 }
3583
3584                 public override Expression Resolve (TypeContainer tc)
3585                 {
3586                         Expr = Expr.Resolve (tc);
3587
3588                         if (Expr == null)
3589                                 return null;
3590
3591                         eclass = Expr.ExprClass;
3592                         type = Expr.Type;
3593                         return this;
3594                 }
3595
3596                 public override void Emit (EmitContext ec)
3597                 {
3598                         bool last_check = ec.CheckState;
3599
3600                         ec.CheckState = false;
3601                         Expr.Emit (ec);
3602                         ec.CheckState = last_check;
3603                 }
3604
3605         }
3606
3607         public class ElementAccess : Expression {
3608
3609                 public readonly ArrayList  Arguments;
3610                 public readonly Expression Expr;
3611
3612                 public ElementAccess (Expression e, ArrayList e_list)
3613                 {
3614                         Expr = e;
3615                         Arguments = e_list;
3616                 }
3617
3618                 public override Expression Resolve (TypeContainer tc)
3619                 {
3620                         // FIXME: Implement;
3621                         throw new Exception ("Unimplemented");
3622                         // return this;
3623                 }
3624
3625                 public override void Emit (EmitContext ec)
3626                 {
3627                         // FIXME : Implement !
3628                         throw new Exception ("Unimplemented");
3629                 }
3630
3631         }
3632
3633         public class BaseAccess : Expression {
3634
3635                 public enum BaseAccessType {
3636                         Member,
3637                         Indexer
3638                 };
3639
3640                 public readonly BaseAccessType BAType;
3641                 public readonly string         Member;
3642                 public readonly ArrayList      Arguments;
3643
3644                 public BaseAccess (BaseAccessType t, string member, ArrayList args)
3645                 {
3646                         BAType = t;
3647                         Member = member;
3648                         Arguments = args;
3649
3650                 }
3651
3652                 public override Expression Resolve (TypeContainer tc)
3653                 {
3654                         // FIXME: Implement;
3655                         throw new Exception ("Unimplemented");
3656                         // return this;
3657                 }
3658
3659                 public override void Emit (EmitContext ec)
3660                 {
3661                         throw new Exception ("Unimplemented");
3662                 }
3663         }
3664
3665         public class UserImplicitCast : Expression {
3666                 MethodBase method;
3667                 ArrayList  arguments;
3668
3669                 public UserImplicitCast (MethodInfo method, ArrayList arguments)
3670                 {
3671                         this.method = method;
3672                         this.arguments = arguments;
3673                         type = method.ReturnType;
3674                         eclass = ExprClass.Value;
3675                 }
3676
3677                 public override Expression Resolve (TypeContainer tc)
3678                 {
3679                         //
3680                         // We are born in a fully resolved state
3681                         //
3682                         return this;
3683                 }
3684
3685                 public static Expression CanConvert (TypeContainer tc, Expression source, Type target)
3686                 {
3687                         Expression mg1, mg2;
3688                         MethodBase method;
3689                         ArrayList arguments;
3690
3691                         mg1 = MemberLookup (tc, source.Type, "op_Implicit", false);
3692                         mg2 = MemberLookup (tc, target, "op_Implicit", false);
3693
3694                         MethodGroupExpr union = Invocation.MakeUnionSet (mg1, mg2);
3695
3696                         if (union != null) {
3697                                 arguments = new ArrayList ();
3698                                 arguments.Add (new Argument (source, Argument.AType.Expression));
3699
3700                                 method = Invocation.OverloadResolve (tc, union, arguments,
3701                                                                      new Location ("FIXME", 1, 1));
3702
3703                                 if (method != null) {
3704                                         MethodInfo mi = (MethodInfo) method;
3705
3706                                         if (mi.ReturnType == target)
3707                                                 return new UserImplicitCast (mi, arguments);
3708                                 }
3709                         }
3710
3711                         // If we have a boolean type, we need to check for the True
3712                         // and False operators too.
3713
3714                         if (target == TypeManager.bool_type) {
3715
3716                                 mg1 = MemberLookup (tc, source.Type, "op_True", false);
3717                                 mg2 = MemberLookup (tc, target, "op_True", false);
3718
3719                                 union = Invocation.MakeUnionSet (mg1, mg2);
3720
3721                                 if (union == null)
3722                                         return null;
3723
3724                                 arguments = new ArrayList ();
3725                                 arguments.Add (new Argument (source, Argument.AType.Expression));
3726
3727                                 method = Invocation.OverloadResolve (tc, union, arguments,
3728                                                                      new Location ("FIXME", 1, 1));
3729                                 if (method != null) {
3730                                         MethodInfo mi = (MethodInfo) method;
3731
3732                                         if (mi.ReturnType == target)
3733                                                 return new UserImplicitCast (mi, arguments);
3734                                 }
3735                         }
3736
3737                         return null;
3738                 }
3739
3740                 public override void Emit (EmitContext ec)
3741                 {
3742                         ILGenerator ig = ec.ig;
3743
3744                         if (method != null) {
3745
3746                                 // Note that operators are static anyway
3747
3748                                 if (arguments != null)
3749                                         Invocation.EmitArguments (ec, method, arguments);
3750
3751                                 if (method is MethodInfo)
3752                                         ig.Emit (OpCodes.Call, (MethodInfo) method);
3753                                 else
3754                                         ig.Emit (OpCodes.Call, (ConstructorInfo) method);
3755
3756                                 return;
3757                         }
3758
3759                         throw new Exception ("Implement me");
3760                 }
3761
3762         }
3763 }