source: stable/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Parser/mcs/linq.cs

//
// linq.cs: support for query expressions
//
// Authors: Marek Safar (marek.safar@gmail.com)
//
// Dual licensed under the terms of the MIT X11 or GNU GPL
//
// Copyright 2007-2008 Novell, Inc
// Copyright 2011 Xamarin Inc
//

using System;
using System.Collections.Generic;

namespace Mono.CSharp.Linq
{
  public class QueryExpression : AQueryClause
  {
    public QueryExpression (AQueryClause start)
      : base (null, null, start.Location)
    {
      this.next = start;
    }

    public override Expression BuildQueryClause (ResolveContext ec, Expression lSide, Parameter parentParameter)
    {
      return next.BuildQueryClause (ec, lSide, parentParameter);
    }

    protected override Expression DoResolve (ResolveContext ec)
    {
      int counter = QueryBlock.TransparentParameter.Counter;

      Expression e = BuildQueryClause (ec, null, null);
      if (e != null)
        e = e.Resolve (ec);

      //
      // Reset counter in probing mode to ensure that all transparent
      // identifier anonymous types are created only once
      //
      if (ec.IsInProbingMode)
        QueryBlock.TransparentParameter.Counter = counter;

      return e;
    }

    protected override string MethodName {
      get { throw new NotSupportedException (); }
    }
    
    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  public abstract class AQueryClause : ShimExpression
  {
    protected class QueryExpressionAccess : MemberAccess
    {
      public QueryExpressionAccess (Expression expr, string methodName, Location loc)
        : base (expr, methodName, loc)
      {
      }

      public QueryExpressionAccess (Expression expr, string methodName, TypeArguments typeArguments, Location loc)
        : base (expr, methodName, typeArguments, loc)
      {
      }

      protected override void Error_TypeDoesNotContainDefinition (ResolveContext ec, TypeSpec type, string name)
      {
        ec.Report.Error (1935, loc, "An implementation of `{0}' query expression pattern could not be found. " +
          "Are you missing `System.Linq' using directive or `System.Core.dll' assembly reference?",
          name);
      }
    }

    protected class QueryExpressionInvocation : Invocation, OverloadResolver.IErrorHandler
    {
      public QueryExpressionInvocation (QueryExpressionAccess expr, Arguments arguments)
        : base (expr, arguments)
      {
      }

      protected override MethodGroupExpr DoResolveOverload (ResolveContext ec)
      {
        MethodGroupExpr rmg = mg.OverloadResolve (ec, ref arguments, this, OverloadResolver.Restrictions.None);
        return rmg;
      }

      protected override Expression DoResolveDynamic (ResolveContext ec, Expression memberExpr)
      {
        ec.Report.Error (1979, loc,
          "Query expressions with a source or join sequence of type `dynamic' are not allowed");
        return null;
      }

      #region IErrorHandler Members

      bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
      {
        ec.Report.SymbolRelatedToPreviousError (best);
        ec.Report.SymbolRelatedToPreviousError (ambiguous);
        ec.Report.Error (1940, loc, "Ambiguous implementation of the query pattern `{0}' for source type `{1}'",
          best.Name, mg.InstanceExpression.GetSignatureForError ());
        return true;
      }

      bool OverloadResolver.IErrorHandler.ArgumentMismatch (ResolveContext rc, MemberSpec best, Argument arg, int index)
      {
        return false;
      }

      bool OverloadResolver.IErrorHandler.NoArgumentMatch (ResolveContext rc, MemberSpec best)
      {
        return false;
      }

      bool OverloadResolver.IErrorHandler.TypeInferenceFailed (ResolveContext rc, MemberSpec best)
      {
        var ms = (MethodSpec) best;
        TypeSpec source_type = ms.Parameters.ExtensionMethodType;
        if (source_type != null) {
          Argument a = arguments[0];

          if (TypeManager.IsGenericType (source_type) && InflatedTypeSpec.ContainsTypeParameter (source_type)) {
            TypeInferenceContext tic = new TypeInferenceContext (source_type.TypeArguments);
            tic.OutputTypeInference (rc, a.Expr, source_type);
            if (tic.FixAllTypes (rc)) {
              source_type = source_type.GetDefinition ().MakeGenericType (rc, tic.InferredTypeArguments);
            }
          }

          if (!Convert.ImplicitConversionExists (rc, a.Expr, source_type)) {
            rc.Report.Error (1936, loc, "An implementation of `{0}' query expression pattern for source type `{1}' could not be found",
              best.Name, a.Type.GetSignatureForError ());
            return true;
          }
        }

        if (best.Name == "SelectMany") {
          rc.Report.Error (1943, loc,
            "An expression type is incorrect in a subsequent `from' clause in a query expression with source type `{0}'",
            arguments[0].GetSignatureForError ());
        } else {
          rc.Report.Error (1942, loc,
            "An expression type in `{0}' clause is incorrect. Type inference failed in the call to `{1}'",
            best.Name.ToLowerInvariant (), best.Name);
        }

        return true;
      }

      #endregion
    }

    public AQueryClause next;
    public QueryBlock block;

    protected AQueryClause (QueryBlock block, Expression expr, Location loc)
       : base (expr)
    {
      this.block = block;
      this.loc = loc;
    }
    
    protected override void CloneTo (CloneContext clonectx, Expression target)
    {
      base.CloneTo (clonectx, target);

      AQueryClause t = (AQueryClause) target;

      if (block != null)
        t.block = (QueryBlock) clonectx.LookupBlock (block);

      if (next != null)
        t.next = (AQueryClause) next.Clone (clonectx);
    }

    protected override Expression DoResolve (ResolveContext ec)
    {
      return expr.Resolve (ec);
    }

    public virtual Expression BuildQueryClause (ResolveContext ec, Expression lSide, Parameter parameter)
    {
      Arguments args = null;
      CreateArguments (ec, parameter, ref args);
      lSide = CreateQueryExpression (lSide, args);
      if (next != null) {
        parameter = CreateChildrenParameters (parameter);

        Select s = next as Select;
        if (s == null || s.IsRequired (parameter))
          return next.BuildQueryClause (ec, lSide, parameter);
          
        // Skip transparent select clause if any clause follows
        if (next.next != null)
          return next.next.BuildQueryClause (ec, lSide, parameter);
      }

      return lSide;
    }

    protected virtual Parameter CreateChildrenParameters (Parameter parameter)
    {
      // Have to clone the parameter for any children use, it carries block sensitive data
      return parameter.Clone ();
    }

    protected virtual void CreateArguments (ResolveContext ec, Parameter parameter, ref Arguments args)
    {
      args = new Arguments (2);

      LambdaExpression selector = new LambdaExpression (loc);

      block.SetParameter (parameter);
      selector.Block = block;
      selector.Block.AddStatement (new ContextualReturn (expr));

      args.Add (new Argument (selector));
    }

    protected Invocation CreateQueryExpression (Expression lSide, Arguments arguments)
    {
      return new QueryExpressionInvocation (
        new QueryExpressionAccess (lSide, MethodName, loc), arguments);
    }

    protected abstract string MethodName { get; }

    public AQueryClause Next {
      set {
        next = value;
      }
    }

    public AQueryClause Tail {
      get {
        return next == null ? this : next.Tail;
      }
    }
  }

  //
  // A query clause with an identifier (range variable)
  //
  public abstract class ARangeVariableQueryClause : AQueryClause
  {
    sealed class RangeAnonymousTypeParameter : AnonymousTypeParameter
    {
      public RangeAnonymousTypeParameter (Expression initializer, RangeVariable parameter)
        : base (initializer, parameter.Name, parameter.Location)
      {
      }

      protected override void Error_InvalidInitializer (ResolveContext ec, string initializer)
      {
        ec.Report.Error (1932, loc, "A range variable `{0}' cannot be initialized with `{1}'",
          Name, initializer);
      }
    }

    class RangeParameterReference : ParameterReference
    {
      Parameter parameter;

      public RangeParameterReference (Parameter p)
        : base (null, p.Location)
      {
        this.parameter = p;
      }

      protected override Expression DoResolve (ResolveContext ec)
      {
        pi = ec.CurrentBlock.ParametersBlock.GetParameterInfo (parameter);
        return base.DoResolve (ec);
      }
    }

    protected RangeVariable identifier;
    
    public RangeVariable  IntoVariable {
      get {
        return identifier;
      }
    }
    
    protected ARangeVariableQueryClause (QueryBlock block, RangeVariable identifier, Expression expr, Location loc)
      : base (block, expr, loc)
    {
      this.identifier = identifier;
    }

    public RangeVariable Identifier {
      get {
        return identifier;
      }
    }

    public FullNamedExpression IdentifierType { get; set; }

    protected Invocation CreateCastExpression (Expression lSide)
    {
      return new QueryExpressionInvocation (
        new QueryExpressionAccess (lSide, "Cast", new TypeArguments (IdentifierType), loc), null);
    }

    protected override Parameter CreateChildrenParameters (Parameter parameter)
    {
      return new QueryBlock.TransparentParameter (parameter.Clone (), GetIntoVariable ());
    }

    protected static Expression CreateRangeVariableType (ResolveContext rc, Parameter parameter, RangeVariable name, Expression init)
    {
      var args = new List<AnonymousTypeParameter> (2);

      //
      // The first argument is the reference to the parameter
      //
      args.Add (new AnonymousTypeParameter (new RangeParameterReference (parameter), parameter.Name, parameter.Location));

      //
      // The second argument is the linq expression
      //
      args.Add (new RangeAnonymousTypeParameter (init, name));

      //
      // Create unique anonymous type
      //
      return new NewAnonymousType (args, rc.MemberContext.CurrentMemberDefinition.Parent, name.Location);
    }

    protected virtual RangeVariable GetIntoVariable ()
    {
      return identifier;
    }
  }

  public sealed class RangeVariable : INamedBlockVariable
  {
    Block block;

    public RangeVariable (string name, Location loc)
    {
      Name = name;
      Location = loc;
    }

    #region Properties

    public Block Block {
      get {
        return block;
      }
      set {
        block = value;
      }
    }

    public bool IsDeclared {
      get {
        return true;
      }
    }

    public bool IsParameter {
      get {
        return false;
      }
    }

    public Location Location { get; private set; }

    public string Name { get; private set; }

    #endregion

    public Expression CreateReferenceExpression (ResolveContext rc, Location loc)
    {
      // 
      // We know the variable name is somewhere in the scope. This generates
      // an access expression from current block
      //
      var pb = rc.CurrentBlock.ParametersBlock;
      while (true) {
        if (pb is QueryBlock) {
          for (int i = pb.Parameters.Count - 1; i >= 0; --i) {
            var p = pb.Parameters[i];
            if (p.Name == Name)
              return pb.GetParameterReference (i, loc);

            Expression expr = null;
            var tp = p as QueryBlock.TransparentParameter;
            while (tp != null) {
              if (expr == null)
                expr = pb.GetParameterReference (i, loc);
              else
                expr = new TransparentMemberAccess (expr, tp.Name);

              if (tp.Identifier == Name)
                return new TransparentMemberAccess (expr, Name);

              if (tp.Parent.Name == Name)
                return new TransparentMemberAccess (expr, Name);

              tp = tp.Parent as QueryBlock.TransparentParameter;
            }
          }
        }

        if (pb == block)
          return null;

        pb = pb.Parent.ParametersBlock;
      }
    }
  }

  public class QueryStartClause : ARangeVariableQueryClause
  {
    public QueryStartClause (QueryBlock block, Expression expr, RangeVariable identifier, Location loc)
      : base (block, identifier, expr, loc)
    {
      block.AddRangeVariable (identifier);
    }

    public override Expression BuildQueryClause (ResolveContext ec, Expression lSide, Parameter parameter)
    {
      if (IdentifierType != null)
        expr = CreateCastExpression (expr);

      if (parameter == null)
        lSide = expr;

      return next.BuildQueryClause (ec, lSide, new ImplicitLambdaParameter (identifier.Name, identifier.Location));
    }

    protected override Expression DoResolve (ResolveContext ec)
    {
      Expression e = BuildQueryClause (ec, null, null);
      return e.Resolve (ec);
    }

    protected override string MethodName {
      get { throw new NotSupportedException (); }
    }
    
    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }


  public class GroupBy : AQueryClause
  {
    Expression element_selector;
    QueryBlock element_block;

    public Expression ElementSelector {
      get { return this.element_selector; }
    }

    public GroupBy (QueryBlock block, Expression elementSelector, QueryBlock elementBlock, Expression keySelector, Location loc)
      : base (block, keySelector, loc)
    {
      //
      // Optimizes clauses like `group A by A'
      //
      if (!elementSelector.Equals (keySelector)) {
        this.element_selector = elementSelector;
        this.element_block = elementBlock;
      }
    }

    public Expression SelectorExpression {
      get {
        return element_selector;
      }
    }

    protected override void CreateArguments (ResolveContext ec, Parameter parameter, ref Arguments args)
    {
      base.CreateArguments (ec, parameter, ref args);

      if (element_selector != null) {
        LambdaExpression lambda = new LambdaExpression (element_selector.Location);

        element_block.SetParameter (parameter.Clone ());
        lambda.Block = element_block;
        lambda.Block.AddStatement (new ContextualReturn (element_selector));
        args.Add (new Argument (lambda));
      }
    }

    protected override void CloneTo (CloneContext clonectx, Expression target)
    {
      GroupBy t = (GroupBy) target;
      if (element_selector != null) {
        t.element_selector = element_selector.Clone (clonectx);
        t.element_block = (QueryBlock) element_block.Clone (clonectx);
      }

      base.CloneTo (clonectx, t);
    }

    protected override string MethodName {
      get { return "GroupBy"; }
    }
    
    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  public class Join : SelectMany
  {
    QueryBlock inner_selector, outer_selector;

    public RangeVariable JoinVariable {
      get { return this.GetIntoVariable (); }
    }
    
    public Join (QueryBlock block, RangeVariable lt, Expression inner, QueryBlock outerSelector, QueryBlock innerSelector, Location loc)
      : base (block, lt, inner, loc)
    {
      this.outer_selector = outerSelector;
      this.inner_selector = innerSelector;
    }

    public QueryBlock InnerSelector {
      get {
        return inner_selector;
      }
    }
    
    public QueryBlock OuterSelector {
      get {
        return outer_selector;
      }
    }

    protected override void CreateArguments (ResolveContext ec, Parameter parameter, ref Arguments args)
    {
      args = new Arguments (4);

      if (IdentifierType != null)
        expr = CreateCastExpression (expr);

      args.Add (new Argument (expr));

      outer_selector.SetParameter (parameter.Clone ());
      var lambda = new LambdaExpression (outer_selector.StartLocation);
      lambda.Block = outer_selector;
      args.Add (new Argument (lambda));

      inner_selector.SetParameter (new ImplicitLambdaParameter (identifier.Name, identifier.Location));
      lambda = new LambdaExpression (inner_selector.StartLocation);
      lambda.Block = inner_selector;
      args.Add (new Argument (lambda));

      base.CreateArguments (ec, parameter, ref args);
    }

    protected override void CloneTo (CloneContext clonectx, Expression target)
    {
      Join t = (Join) target;
      t.inner_selector = (QueryBlock) inner_selector.Clone (clonectx);
      t.outer_selector = (QueryBlock) outer_selector.Clone (clonectx);
      base.CloneTo (clonectx, t);
    } 

    protected override string MethodName {
      get { return "Join"; }
    }
    
    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  public class GroupJoin : Join
  {
    readonly RangeVariable into;

    public GroupJoin (QueryBlock block, RangeVariable lt, Expression inner,
      QueryBlock outerSelector, QueryBlock innerSelector, RangeVariable into, Location loc)
      : base (block, lt, inner, outerSelector, innerSelector, loc)
    {
      this.into = into;
    }

    protected override RangeVariable GetIntoVariable ()
    {
      return into;
    }

    protected override string MethodName {
      get { return "GroupJoin"; }
    }
    
    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  public class Let : ARangeVariableQueryClause
  {
    public Let (QueryBlock block, RangeVariable identifier, Expression expr, Location loc)
      : base (block, identifier, expr, loc)
    {
    }

    protected override void CreateArguments (ResolveContext ec, Parameter parameter, ref Arguments args)
    {
      expr = CreateRangeVariableType (ec, parameter, identifier, expr);
      base.CreateArguments (ec, parameter, ref args);
    }

    protected override string MethodName {
      get { return "Select"; }
    }
    
    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  public class Select : AQueryClause
  {
    public Select (QueryBlock block, Expression expr, Location loc)
      : base (block, expr, loc)
    {
    }
    
    //
    // For queries like `from a orderby a select a'
    // the projection is transparent and select clause can be safely removed 
    //
    public bool IsRequired (Parameter parameter)
    {
      SimpleName sn = expr as SimpleName;
      if (sn == null)
        return true;

      return sn.Name != parameter.Name;
    }

    protected override string MethodName {
      get { return "Select"; }
    }
    
    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }

  }

  public class SelectMany : ARangeVariableQueryClause
  {
    public SelectMany (QueryBlock block, RangeVariable identifier, Expression expr, Location loc)
      : base (block, identifier, expr, loc)
    {
    }

    protected override void CreateArguments (ResolveContext ec, Parameter parameter, ref Arguments args)
    {
      if (args == null) {
        if (IdentifierType != null)
          expr = CreateCastExpression (expr);

        base.CreateArguments (ec, parameter.Clone (), ref args);
      }

      Expression result_selector_expr;
      QueryBlock result_block;

      var target = GetIntoVariable ();
      var target_param = new ImplicitLambdaParameter (target.Name, target.Location);

      //
      // When select follows use it as a result selector
      //
      if (next is Select) {
        result_selector_expr = next.Expr;

        result_block = next.block;
        result_block.SetParameters (parameter, target_param);

        next = next.next;
      } else {
        result_selector_expr = CreateRangeVariableType (ec, parameter, target, new SimpleName (target.Name, target.Location));

        result_block = new QueryBlock (block.Parent, block.StartLocation);
        result_block.SetParameters (parameter, target_param);
      }

      LambdaExpression result_selector = new LambdaExpression (Location);
      result_selector.Block = result_block;
      result_selector.Block.AddStatement (new ContextualReturn (result_selector_expr));

      args.Add (new Argument (result_selector));
    }

    protected override string MethodName {
      get { return "SelectMany"; }
    }

    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  public class Where : AQueryClause
  {
    public Where (QueryBlock block, Expression expr, Location loc)
      : base (block, expr, loc)
    {
    }

    protected override string MethodName {
      get { return "Where"; }
    }

    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  public class OrderByAscending : AQueryClause
  {
    public OrderByAscending (QueryBlock block, Expression expr)
      : base (block, expr, expr.Location)
    {
    }

    protected override string MethodName {
      get { return "OrderBy"; }
    }

    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  public class OrderByDescending : AQueryClause
  {
    public OrderByDescending (QueryBlock block, Expression expr)
      : base (block, expr, expr.Location)
    {
    }

    protected override string MethodName {
      get { return "OrderByDescending"; }
    }

    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  public class ThenByAscending : OrderByAscending
  {
    public ThenByAscending (QueryBlock block, Expression expr)
      : base (block, expr)
    {
    }

    protected override string MethodName {
      get { return "ThenBy"; }
    }

    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  public class ThenByDescending : OrderByDescending
  {
    public ThenByDescending (QueryBlock block, Expression expr)
      : base (block, expr)
    {
    }

    protected override string MethodName {
      get { return "ThenByDescending"; }
    }

    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  //
  // Implicit query block
  //
  public class QueryBlock : ParametersBlock
  {
    //
    // Transparent parameters are used to package up the intermediate results
    // and pass them onto next clause
    //
    public sealed class TransparentParameter : ImplicitLambdaParameter
    {
      public static int Counter;
      const string ParameterNamePrefix = "<>__TranspIdent";

      public readonly Parameter Parent;
      public readonly string Identifier;

      public TransparentParameter (Parameter parent, RangeVariable identifier)
        : base (ParameterNamePrefix + Counter++, identifier.Location)
      {
        Parent = parent;
        Identifier = identifier.Name;
      }

      public static void Reset ()
      {
        Counter = 0;
      }
    }

    public QueryBlock (Block parent, Location start)
      : base (parent, ParametersCompiled.EmptyReadOnlyParameters, start, Flags.CompilerGenerated)
    {
    }

    public void AddRangeVariable (RangeVariable variable)
    {
      variable.Block = this;
      TopBlock.AddLocalName (variable.Name, variable, true);
    }

    public override void Error_AlreadyDeclared (string name, INamedBlockVariable variable, string reason)
    {
      TopBlock.Report.Error (1931, variable.Location,
        "A range variable `{0}' conflicts with a previous declaration of `{0}'",
        name);
    }

    public override void Error_AlreadyDeclared (string name, INamedBlockVariable variable)
    {
      TopBlock.Report.Error (1930, variable.Location,
        "A range variable `{0}' has already been declared in this scope",
        name);    
    }

    public override void Error_AlreadyDeclaredTypeParameter (string name, Location loc)
    {
      TopBlock.Report.Error (1948, loc,
        "A range variable `{0}' conflicts with a method type parameter",
        name);
    }

    public void SetParameter (Parameter parameter)
    {
      base.parameters = new ParametersCompiled (parameter);
      base.parameter_info = new ParameterInfo[] {
        new ParameterInfo (this, 0)
      };
    }

    public void SetParameters (Parameter first, Parameter second)
    {
      base.parameters = new ParametersCompiled (first, second);
      base.parameter_info = new ParameterInfo[] {
        new ParameterInfo (this, 0),
        new ParameterInfo (this, 1)
      };
    }
  }

  sealed class TransparentMemberAccess : MemberAccess
  {
    public TransparentMemberAccess (Expression expr, string name)
      : base (expr, name)
    {
    }

    public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
    {
      rc.Report.Error (1947, loc,
        "A range variable `{0}' cannot be assigned to. Consider using `let' clause to store the value",
        Name);

      return null;
    }
  }
}