mcs/mcs/linq.cs

   1 //
   2 // linq.cs: support for query expressions
   3 //
   4 // Authors: Marek Safar (marek.safar@gmail.com)
   5 //
   6 // Dual licensed under the terms of the MIT X11 or GNU GPL
   7 //
   8 // Copyright 2007-2008 Novell, Inc
   9 //
  10
  11 using System;
  12 using System.Reflection;
  13 using System.Collections.Generic;
  14
  15 namespace Mono.CSharp.Linq
  16 {
  17         public class QueryExpression : AQueryClause
  18         {
  19                 public QueryExpression (AQueryClause start)
  20                         : base (null, null, Location.Null)
  21                 {
  22                         this.next = start;
  23                 }
  24
  25                 public override Expression BuildQueryClause (ResolveContext ec, Expression lSide, Parameter parentParameter)
  26                 {
  27                         return next.BuildQueryClause (ec, lSide, parentParameter);
  28                 }
  29
  30                 protected override Expression DoResolve (ResolveContext ec)
  31                 {
  32                         int counter = QueryBlock.TransparentParameter.Counter;
  33
  34                         Expression e = BuildQueryClause (ec, null, null);
  35                         if (e != null)
  36                                 e = e.Resolve (ec);
  37
  38                         //
  39                         // Reset counter in probing mode to ensure that all transparent
  40                         // identifier anonymous types are created only once
  41                         //
  42                         if (ec.IsInProbingMode)
  43                                 QueryBlock.TransparentParameter.Counter = counter;
  44
  45                         return e;
  46                 }
  47
  48                 protected override string MethodName {
  49                         get { throw new NotSupportedException (); }
  50                 }
  51         }
  52
  53         public abstract class AQueryClause : ShimExpression
  54         {
  55                 protected class QueryExpressionAccess : MemberAccess
  56                 {
  57                         public QueryExpressionAccess (Expression expr, string methodName, Location loc)
  58                                 : base (expr, methodName, loc)
  59                         {
  60                         }
  61
  62                         public QueryExpressionAccess (Expression expr, string methodName, TypeArguments typeArguments, Location loc)
  63                                 : base (expr, methodName, typeArguments, loc)
  64                         {
  65                         }
  66
  67                         protected override void Error_TypeDoesNotContainDefinition (ResolveContext ec, TypeSpec type, string name)
  68                         {
  69                                 ec.Report.Error (1935, loc, "An implementation of `{0}' query expression pattern could not be found. " +
  70                                         "Are you missing `System.Linq' using directive or `System.Core.dll' assembly reference?",
  71                                         name);
  72                         }
  73                 }
  74
  75                 protected class QueryExpressionInvocation : Invocation, OverloadResolver.IErrorHandler
  76                 {
  77                         public QueryExpressionInvocation (QueryExpressionAccess expr, Arguments arguments)
  78                                 : base (expr, arguments)
  79                         {
  80                         }
  81
  82                         protected override MethodGroupExpr DoResolveOverload (ResolveContext ec)
  83                         {
  84                                 MethodGroupExpr rmg = mg.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.None);
  85                                 return rmg;
  86                         }
  87
  88                         #region IErrorHandler Members
  89
  90                         bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
  91                         {
  92                                 ec.Report.SymbolRelatedToPreviousError (best);
  93                                 ec.Report.SymbolRelatedToPreviousError (ambiguous);
  94                                 ec.Report.Error (1940, loc, "Ambiguous implementation of the query pattern `{0}' for source type `{1}'",
  95                                         best.Name, mg.InstanceExpression.GetSignatureForError ());
  96                                 return true;
  97                         }
  98
  99                         bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
 100                         {
 101                                 return false;
 102                         }
 103
 104                         bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
 105                         {
 106                                 return false;
 107                         }
 108
 109                         bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
 110                         {
 111                                 var ms = (MethodSpec) best;
 112                                 TypeSpec source_type = ms.Parameters.ExtensionMethodType;
 113                                 if (source_type != null) {
 114                                         Argument a = arguments[0];
 115
 116                                         if (TypeManager.IsGenericType (source_type) && TypeManager.ContainsGenericParameters (source_type)) {
 117                                                 TypeInferenceContext tic = new TypeInferenceContext (source_type.TypeArguments);
 118                                                 tic.OutputTypeInference (rc, a.Expr, source_type);
 119                                                 if (tic.FixAllTypes (rc)) {
 120                                                         source_type = source_type.GetDefinition ().MakeGenericType (tic.InferredTypeArguments);
 121                                                 }
 122                                         }
 123
 124                                         if (!Convert.ImplicitConversionExists (rc, a.Expr, source_type)) {
 125                                                 rc.Report.Error (1936, loc, "An implementation of `{0}' query expression pattern for source type `{1}' could not be found",
 126                                                         best.Name, TypeManager.CSharpName (a.Type));
 127                                                 return true;
 128                                         }
 129                                 }
 130
 131                                 if (best.Name == "SelectMany") {
 132                                         rc.Report.Error (1943, loc,
 133                                                 "An expression type is incorrect in a subsequent `from' clause in a query expression with source type `{0}'",
 134                                                 arguments[0].GetSignatureForError ());
 135                                 } else {
 136                                         rc.Report.Error (1942, loc,
 137                                                 "An expression type in `{0}' clause is incorrect. Type inference failed in the call to `{1}'",
 138                                                 best.Name.ToLowerInvariant (), best.Name);
 139                                 }
 140
 141                                 return true;
 142                         }
 143
 144                         #endregion
 145                 }
 146
 147                 public AQueryClause next;
 148                 public QueryBlock block;
 149
 150                 protected AQueryClause (QueryBlock block, Expression expr, Location loc)
 151                          : base (expr)
 152                 {
 153                         this.block = block;
 154                         this.loc = loc;
 155                 }
 156
 157                 protected override void CloneTo (CloneContext clonectx, Expression target)
 158                 {
 159                         base.CloneTo (clonectx, target);
 160
 161                         AQueryClause t = (AQueryClause) target;
 162
 163                         if (block != null)
 164                                 t.block = (QueryBlock) clonectx.LookupBlock (block);
 165
 166                         if (next != null)
 167                                 t.next = (AQueryClause) next.Clone (clonectx);
 168                 }
 169
 170                 protected override Expression DoResolve (ResolveContext ec)
 171                 {
 172                         return expr.Resolve (ec);
 173                 }
 174
 175                 public virtual Expression BuildQueryClause (ResolveContext ec, Expression lSide, Parameter parameter)
 176                 {
 177                         Arguments args = null;
 178                         CreateArguments (ec, parameter, ref args);
 179                         lSide = CreateQueryExpression (lSide, args);
 180                         if (next != null) {
 181                                 parameter = CreateChildrenParameters (parameter);
 182
 183                                 Select s = next as Select;
 184                                 if (s == null || s.IsRequired (parameter))
 185                                         return next.BuildQueryClause (ec, lSide, parameter);
 186
 187                                 // Skip transparent select clause if any clause follows
 188                                 if (next.next != null)
 189                                         return next.next.BuildQueryClause (ec, lSide, parameter);
 190                         }
 191
 192                         return lSide;
 193                 }
 194
 195                 protected virtual Parameter CreateChildrenParameters (Parameter parameter)
 196                 {
 197                         // Have to clone the parameter for any children use, it carries block sensitive data
 198                         return parameter.Clone ();
 199                 }
 200
 201                 protected virtual void CreateArguments (ResolveContext ec, Parameter parameter, ref Arguments args)
 202                 {
 203                         args = new Arguments (2);
 204
 205                         LambdaExpression selector = new LambdaExpression (loc);
 206
 207                         block.SetParameter (parameter);
 208                         selector.Block = block;
 209                         selector.Block.AddStatement (new ContextualReturn (expr));
 210
 211                         args.Add (new Argument (selector));
 212                 }
 213
 214                 protected Invocation CreateQueryExpression (Expression lSide, Arguments arguments)
 215                 {
 216                         return new QueryExpressionInvocation (
 217                                 new QueryExpressionAccess (lSide, MethodName, loc), arguments);
 218                 }
 219
 220                 protected abstract string MethodName { get; }
 221
 222                 public AQueryClause Next {
 223                         set {
 224                                 next = value;
 225                         }
 226                 }
 227
 228                 public AQueryClause Tail {
 229                         get {
 230                                 return next == null ? this : next.Tail;
 231                         }
 232                 }
 233         }
 234
 235         //
 236         // A query clause with an identifier (range variable)
 237         //
 238         public abstract class ARangeVariableQueryClause : AQueryClause
 239         {
 240                 sealed class RangeAnonymousTypeParameter : AnonymousTypeParameter
 241                 {
 242                         public RangeAnonymousTypeParameter (Expression initializer, RangeVariable parameter)
 243                                 : base (initializer, parameter.Name, parameter.Location)
 244                         {
 245                         }
 246
 247                         protected override void Error_InvalidInitializer (ResolveContext ec, string initializer)
 248                         {
 249                                 ec.Report.Error (1932, loc, "A range variable `{0}' cannot be initialized with `{1}'",
 250                                         Name, initializer);
 251                         }
 252                 }
 253
 254                 class RangeParameterReference : ParameterReference
 255                 {
 256                         Parameter parameter;
 257
 258                         public RangeParameterReference (Parameter p)
 259                                 : base (null, p.Location)
 260                         {
 261                                 this.parameter = p;
 262                         }
 263
 264                         protected override Expression DoResolve (ResolveContext ec)
 265                         {
 266                                 pi = ec.CurrentBlock.ParametersBlock.GetParameterInfo (parameter);
 267                                 return base.DoResolve (ec);
 268                         }
 269                 }
 270
 271                 protected RangeVariable identifier;
 272
 273                 protected ARangeVariableQueryClause (QueryBlock block, RangeVariable identifier, Expression expr, Location loc)
 274                         : base (block, expr, loc)
 275                 {
 276                         this.identifier = identifier;
 277                 }
 278
 279                 public FullNamedExpression IdentifierType { get; set; }
 280
 281                 protected Invocation CreateCastExpression (Expression lSide)
 282                 {
 283                         return new QueryExpressionInvocation (
 284                                 new QueryExpressionAccess (lSide, "Cast", new TypeArguments (IdentifierType), loc), null);
 285                 }
 286
 287                 protected override Parameter CreateChildrenParameters (Parameter parameter)
 288                 {
 289                         return new QueryBlock.TransparentParameter (parameter.Clone (), GetIntoVariable ());
 290                 }
 291
 292                 protected static Expression CreateRangeVariableType (ResolveContext rc, Parameter parameter, RangeVariable name, Expression init)
 293                 {
 294                         var args = new List<AnonymousTypeParameter> (2);
 295
 296                         //
 297                         // The first argument is the reference to the parameter
 298                         //
 299                         args.Add (new AnonymousTypeParameter (new RangeParameterReference (parameter), parameter.Name, parameter.Location));
 300
 301                         //
 302                         // The second argument is the linq expression
 303                         //
 304                         args.Add (new RangeAnonymousTypeParameter (init, name));
 305
 306                         //
 307                         // Create unique anonymous type
 308                         //
 309                         return new NewAnonymousType (args, rc.MemberContext.CurrentMemberDefinition.Parent, name.Location);
 310                 }
 311
 312                 protected virtual RangeVariable GetIntoVariable ()
 313                 {
 314                         return identifier;
 315                 }
 316         }
 317
 318         public sealed class RangeVariable : INamedBlockVariable
 319         {
 320                 Block block;
 321
 322                 public RangeVariable (string name, Location loc)
 323                 {
 324                         Name = name;
 325                         Location = loc;
 326                 }
 327
 328                 #region Properties
 329
 330                 public Block Block {
 331                         get {
 332                                 return block;
 333                         }
 334                         set {
 335                                 block = value;
 336                         }
 337                 }
 338
 339                 public bool IsDeclared {
 340                         get {
 341                                 return true;
 342                         }
 343                 }
 344
 345                 public Location Location { get; private set; }
 346
 347                 public string Name { get; private set; }
 348
 349                 #endregion
 350
 351                 public Expression CreateReferenceExpression (ResolveContext rc, Location loc)
 352                 {
 353                         Expression expr = null;
 354
 355                         //
 356                         // We know the variable name is somewhere in the scope. This generates
 357                         // an access expression from current block
 358                         //
 359                         var pb = rc.CurrentBlock.ParametersBlock;
 360                         while (true) {
 361                                 if (pb is QueryBlock) {
 362                                         for (int i = pb.Parameters.Count - 1; i >= 0; --i) {
 363                                                 var p = pb.Parameters[i];
 364                                                 if (p.Name == Name)
 365                                                         return pb.GetParameterReference (i, loc);
 366
 367                                                 var tp = p as QueryBlock.TransparentParameter;
 368                                                 while (tp != null) {
 369                                                         if (expr == null)
 370                                                                 expr = pb.GetParameterReference (i, loc);
 371                                                         else
 372                                                                 expr = new TransparentMemberAccess (expr, tp.Name);
 373
 374                                                         if (tp.Identifier == Name)
 375                                                                 return new TransparentMemberAccess (expr, Name);
 376
 377                                                         if (tp.Parent.Name == Name)
 378                                                                 return new TransparentMemberAccess (expr, Name);
 379
 380                                                         tp = tp.Parent as QueryBlock.TransparentParameter;
 381                                                 }
 382                                         }
 383
 384                                         expr = null;
 385                                 }
 386
 387                                 if (pb == block)
 388                                         return null;
 389
 390                                 pb = pb.Parent.ParametersBlock;
 391                         }
 392                 }
 393         }
 394
 395         class QueryStartClause : ARangeVariableQueryClause
 396         {
 397                 public QueryStartClause (QueryBlock block, Expression expr, RangeVariable identifier, Location loc)
 398                         : base (block, identifier, expr, loc)
 399                 {
 400                         block.AddRangeVariable (identifier);
 401                 }
 402
 403                 public override Expression BuildQueryClause (ResolveContext ec, Expression lSide, Parameter parameter)
 404                 {
 405 /*
 406                         expr = expr.Resolve (ec);
 407                         if (expr == null)
 408                                 return null;
 409
 410                         if (expr.Type == InternalType.Dynamic || expr.Type == TypeManager.void_type) {
 411                                 ec.Report.Error (1979, expr.Location,
 412                                         "Query expression with a source or join sequence of type `{0}' is not allowed",
 413                                         TypeManager.CSharpName (expr.Type));
 414                                 return null;
 415                         }
 416 */
 417
 418                         if (IdentifierType != null)
 419                                 expr = CreateCastExpression (expr);
 420
 421                         if (parameter == null)
 422                                 lSide = expr;
 423
 424                         return next.BuildQueryClause (ec, lSide, new ImplicitLambdaParameter (identifier.Name, identifier.Location));
 425                 }
 426
 427                 protected override Expression DoResolve (ResolveContext ec)
 428                 {
 429                         Expression e = BuildQueryClause (ec, null, null);
 430                         return e.Resolve (ec);
 431                 }
 432
 433                 protected override string MethodName {
 434                         get { throw new NotSupportedException (); }
 435                 }
 436         }
 437
 438         public class GroupBy : AQueryClause
 439         {
 440                 Expression element_selector;
 441                 QueryBlock element_block;
 442
 443                 public GroupBy (QueryBlock block, Expression elementSelector, QueryBlock elementBlock, Expression keySelector, Location loc)
 444                         : base (block, keySelector, loc)
 445                 {
 446                         //
 447                         // Optimizes clauses like `group A by A'
 448                         //
 449                         if (!elementSelector.Equals (keySelector)) {
 450                                 this.element_selector = elementSelector;
 451                                 this.element_block = elementBlock;
 452                         }
 453                 }
 454
 455                 protected override void CreateArguments (ResolveContext ec, Parameter parameter, ref Arguments args)
 456                 {
 457                         base.CreateArguments (ec, parameter, ref args);
 458
 459                         if (element_selector != null) {
 460                                 LambdaExpression lambda = new LambdaExpression (element_selector.Location);
 461
 462                                 element_block.SetParameter (parameter.Clone ());
 463                                 lambda.Block = element_block;
 464                                 lambda.Block.AddStatement (new ContextualReturn (element_selector));
 465                                 args.Add (new Argument (lambda));
 466                         }
 467                 }
 468
 469                 protected override void CloneTo (CloneContext clonectx, Expression target)
 470                 {
 471                         GroupBy t = (GroupBy) target;
 472                         if (element_selector != null) {
 473                                 t.element_selector = element_selector.Clone (clonectx);
 474                                 t.element_block = (QueryBlock) element_block.Clone (clonectx);
 475                         }
 476
 477                         base.CloneTo (clonectx, t);
 478                 }
 479
 480                 protected override string MethodName {
 481                         get { return "GroupBy"; }
 482                 }
 483         }
 484
 485         public class Join : SelectMany
 486         {
 487                 QueryBlock inner_selector, outer_selector;
 488
 489                 public Join (QueryBlock block, RangeVariable lt, Expression inner, QueryBlock outerSelector, QueryBlock innerSelector, Location loc)
 490                         : base (block, lt, inner, loc)
 491                 {
 492                         this.outer_selector = outerSelector;
 493                         this.inner_selector = innerSelector;
 494                 }
 495
 496                 protected override void CreateArguments (ResolveContext ec, Parameter parameter, ref Arguments args)
 497                 {
 498                         args = new Arguments (4);
 499
 500                         if (IdentifierType != null)
 501                                 expr = CreateCastExpression (expr);
 502
 503                         args.Add (new Argument (expr));
 504
 505                         outer_selector.SetParameter (parameter.Clone ());
 506                         var lambda = new LambdaExpression (outer_selector.StartLocation);
 507                         lambda.Block = outer_selector;
 508                         args.Add (new Argument (lambda));
 509
 510                         inner_selector.SetParameter (new ImplicitLambdaParameter (identifier.Name, identifier.Location));
 511                         lambda = new LambdaExpression (inner_selector.StartLocation);
 512                         lambda.Block = inner_selector;
 513                         args.Add (new Argument (lambda));
 514
 515                         base.CreateArguments (ec, parameter, ref args);
 516                 }
 517
 518                 protected override void CloneTo (CloneContext clonectx, Expression target)
 519                 {
 520                         Join t = (Join) target;
 521                         t.inner_selector = (QueryBlock) inner_selector.Clone (clonectx);
 522                         t.outer_selector = (QueryBlock) outer_selector.Clone (clonectx);
 523                         base.CloneTo (clonectx, t);
 524                 }
 525
 526                 protected override string MethodName {
 527                         get { return "Join"; }
 528                 }
 529         }
 530
 531         public class GroupJoin : Join
 532         {
 533                 readonly RangeVariable into;
 534
 535                 public GroupJoin (QueryBlock block, RangeVariable lt, Expression inner,
 536                         QueryBlock outerSelector, QueryBlock innerSelector, RangeVariable into, Location loc)
 537                         : base (block, lt, inner, outerSelector, innerSelector, loc)
 538                 {
 539                         this.into = into;
 540                 }
 541
 542                 protected override RangeVariable GetIntoVariable ()
 543                 {
 544                         return into;
 545                 }
 546
 547                 protected override string MethodName {
 548                         get { return "GroupJoin"; }
 549                 }
 550         }
 551
 552         public class Let : ARangeVariableQueryClause
 553         {
 554                 public Let (QueryBlock block, RangeVariable identifier, Expression expr, Location loc)
 555                         : base (block, identifier, expr, loc)
 556                 {
 557                 }
 558
 559                 protected override void CreateArguments (ResolveContext ec, Parameter parameter, ref Arguments args)
 560                 {
 561                         expr = CreateRangeVariableType (ec, parameter, identifier, expr);
 562                         base.CreateArguments (ec, parameter, ref args);
 563                 }
 564
 565                 protected override string MethodName {
 566                         get { return "Select"; }
 567                 }
 568         }
 569
 570         public class Select : AQueryClause
 571         {
 572                 public Select (QueryBlock block, Expression expr, Location loc)
 573                         : base (block, expr, loc)
 574                 {
 575                 }
 576
 577                 //
 578                 // For queries like `from a orderby a select a'
 579                 // the projection is transparent and select clause can be safely removed
 580                 //
 581                 public bool IsRequired (Parameter parameter)
 582                 {
 583                         SimpleName sn = expr as SimpleName;
 584                         if (sn == null)
 585                                 return true;
 586
 587                         return sn.Name != parameter.Name;
 588                 }
 589
 590                 protected override string MethodName {
 591                         get { return "Select"; }
 592                 }
 593         }
 594
 595         public class SelectMany : ARangeVariableQueryClause
 596         {
 597                 public SelectMany (QueryBlock block, RangeVariable identifier, Expression expr, Location loc)
 598                         : base (block, identifier, expr, loc)
 599                 {
 600                 }
 601
 602                 protected override void CreateArguments (ResolveContext ec, Parameter parameter, ref Arguments args)
 603                 {
 604                         if (args == null) {
 605                                 if (IdentifierType != null)
 606                                         expr = CreateCastExpression (expr);
 607
 608                                 base.CreateArguments (ec, parameter, ref args);
 609                         }
 610
 611                         Expression result_selector_expr;
 612                         QueryBlock result_block;
 613
 614                         var target = GetIntoVariable ();
 615                         var target_param = new ImplicitLambdaParameter (target.Name, target.Location);
 616
 617                         //
 618                         // When select follows use it as a result selector
 619                         //
 620                         if (next is Select) {
 621                                 result_selector_expr = next.Expr;
 622
 623                                 result_block = next.block;
 624                                 result_block.SetParameters (parameter, target_param);
 625
 626                                 next = next.next;
 627                         } else {
 628                                 result_selector_expr = CreateRangeVariableType (ec, parameter, target, new SimpleName (target.Name, target.Location));
 629
 630                                 result_block = new QueryBlock (ec.Compiler, block.Parent, block.StartLocation);
 631                                 result_block.SetParameters (parameter, target_param);
 632                         }
 633
 634                         LambdaExpression result_selector = new LambdaExpression (Location);
 635                         result_selector.Block = result_block;
 636                         result_selector.Block.AddStatement (new ContextualReturn (result_selector_expr));
 637
 638                         args.Add (new Argument (result_selector));
 639                 }
 640
 641                 protected override string MethodName {
 642                         get { return "SelectMany"; }
 643                 }
 644         }
 645
 646         public class Where : AQueryClause
 647         {
 648                 public Where (QueryBlock block, BooleanExpression expr, Location loc)
 649                         : base (block, expr, loc)
 650                 {
 651                 }
 652
 653                 protected override string MethodName {
 654                         get { return "Where"; }
 655                 }
 656         }
 657
 658         public class OrderByAscending : AQueryClause
 659         {
 660                 public OrderByAscending (QueryBlock block, Expression expr)
 661                         : base (block, expr, expr.Location)
 662                 {
 663                 }
 664
 665                 protected override string MethodName {
 666                         get { return "OrderBy"; }
 667                 }
 668         }
 669
 670         public class OrderByDescending : AQueryClause
 671         {
 672                 public OrderByDescending (QueryBlock block, Expression expr)
 673                         : base (block, expr, expr.Location)
 674                 {
 675                 }
 676
 677                 protected override string MethodName {
 678                         get { return "OrderByDescending"; }
 679                 }
 680         }
 681
 682         public class ThenByAscending : OrderByAscending
 683         {
 684                 public ThenByAscending (QueryBlock block, Expression expr)
 685                         : base (block, expr)
 686                 {
 687                 }
 688
 689                 protected override string MethodName {
 690                         get { return "ThenBy"; }
 691                 }
 692         }
 693
 694         public class ThenByDescending : OrderByDescending
 695         {
 696                 public ThenByDescending (QueryBlock block, Expression expr)
 697                         : base (block, expr)
 698                 {
 699                 }
 700
 701                 protected override string MethodName {
 702                         get { return "ThenByDescending"; }
 703                 }
 704         }
 705
 706         //
 707         // Implicit query block
 708         //
 709         public class QueryBlock : ParametersBlock
 710         {
 711                 //
 712                 // Transparent parameters are used to package up the intermediate results
 713                 // and pass them onto next clause
 714                 //
 715                 public sealed class TransparentParameter : ImplicitLambdaParameter
 716                 {
 717                         public static int Counter;
 718                         const string ParameterNamePrefix = "<>__TranspIdent";
 719
 720                         public readonly Parameter Parent;
 721                         public readonly string Identifier;
 722
 723                         public TransparentParameter (Parameter parent, RangeVariable identifier)
 724                                 : base (ParameterNamePrefix + Counter++, identifier.Location)
 725                         {
 726                                 Parent = parent;
 727                                 Identifier = identifier.Name;
 728                         }
 729
 730                         public new static void Reset ()
 731                         {
 732                                 Counter = 0;
 733                         }
 734                 }
 735
 736                 public QueryBlock (CompilerContext ctx, Block parent, Location start)
 737                         : base (parent, ParametersCompiled.EmptyReadOnlyParameters, start)
 738                 {
 739                         flags |= Flags.CompilerGenerated;
 740                 }
 741
 742                 public void AddRangeVariable (RangeVariable variable)
 743                 {
 744                         variable.Block = this;
 745                         AddLocalName (variable.Name, variable);
 746                 }
 747
 748                 public override void Error_AlreadyDeclared (string name, INamedBlockVariable variable, string reason)
 749                 {
 750                         TopBlock.Report.Error (1931, variable.Location,
 751                                 "A range variable `{0}' conflicts with a previous declaration of `{0}'",
 752                                 name);
 753                 }
 754
 755                 public override void Error_AlreadyDeclared (string name, INamedBlockVariable variable)
 756                 {
 757                         TopBlock.Report.Error (1930, variable.Location,
 758                                 "A range variable `{0}' has already been declared in this scope",
 759                                 name);
 760                 }
 761
 762                 public override void Error_AlreadyDeclaredTypeParameter (string name, Location loc)
 763                 {
 764                         TopBlock.Report.Error (1948, loc,
 765                                 "A range variable `{0}' conflicts with a method type parameter",
 766                                 name);
 767                 }
 768
 769                 public void SetParameter (Parameter parameter)
 770                 {
 771                         base.parameters = new ParametersCompiled (parameter);
 772                         base.parameter_info = new ParameterInfo[] {
 773                                 new ParameterInfo (this, 0)
 774                         };
 775                 }
 776
 777                 public void SetParameters (Parameter first, Parameter second)
 778                 {
 779                         base.parameters = new ParametersCompiled (first, second);
 780                         base.parameter_info = new ParameterInfo[] {
 781                                 new ParameterInfo (this, 0),
 782                                 new ParameterInfo (this, 1)
 783                         };
 784                 }
 785         }
 786
 787         sealed class TransparentMemberAccess : MemberAccess
 788         {
 789                 public TransparentMemberAccess (Expression expr, string name)
 790                         : base (expr, name)
 791                 {
 792                 }
 793
 794                 public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
 795                 {
 796                         rc.Report.Error (1947, loc,
 797                                 "A range variable `{0}' cannot be assigned to. Consider using `let' clause to store the value",
 798                                 Name);
 799
 800                         return null;
 801                 }
 802         }
 803 }