source: stable/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Parser/mcs/anonymous.cs @ 11937

//
// anonymous.cs: Support for anonymous methods and types
//
// Author:
//   Miguel de Icaza (miguel@ximain.com)
//   Marek Safar (marek.safar@gmail.com)
//
// Dual licensed under the terms of the MIT X11 or GNU GPL
// Copyright 2003-2011 Novell, Inc.
// Copyright 2011 Xamarin Inc
//

using System;
using System.Collections.Generic;
using Mono.CompilerServices.SymbolWriter;
using System.Diagnostics;

#if STATIC
using IKVM.Reflection;
using IKVM.Reflection.Emit;
using System.Diagnostics;
#else
using System.Reflection;
using System.Reflection.Emit;
#endif

namespace Mono.CSharp {

  public abstract class CompilerGeneratedContainer : ClassOrStruct
  {
    protected CompilerGeneratedContainer (TypeContainer parent, MemberName name, Modifiers mod)
      : this (parent, name, mod, MemberKind.Class)
    {
    }

    protected CompilerGeneratedContainer (TypeContainer parent, MemberName name, Modifiers mod, MemberKind kind)
      : base (parent, name, null, kind)
    {
      Debug.Assert ((mod & Modifiers.AccessibilityMask) != 0);

      ModFlags = mod | Modifiers.COMPILER_GENERATED | Modifiers.SEALED;
      spec = new TypeSpec (Kind, null, this, null, ModFlags);
    }

    protected void CheckMembersDefined ()
    {
      if (HasMembersDefined)
        throw new InternalErrorException ("Helper class already defined!");
    }

    protected override bool DoDefineMembers ()
    {
      if (Kind == MemberKind.Class && !IsStatic && !PartialContainer.HasInstanceConstructor) {
        DefineDefaultConstructor (false);
      }

      return base.DoDefineMembers ();
    }

    protected static MemberName MakeMemberName (MemberBase host, string name, int unique_id, TypeParameters tparams, Location loc)
    {
      string host_name = host == null ? null : host is InterfaceMemberBase ? ((InterfaceMemberBase)host).GetFullName (host.MemberName) : host.MemberName.Name;
      string tname = MakeName (host_name, "c", name, unique_id);
      TypeParameters args = null;
      if (tparams != null) {
        args = new TypeParameters (tparams.Count);

        // Type parameters will be filled later when we have TypeContainer
        // instance, for now we need only correct arity to create valid name
        for (int i = 0; i < tparams.Count; ++i)
          args.Add ((TypeParameter) null);
      }

      return new MemberName (tname, args, loc);
    }

    public static string MakeName (string host, string typePrefix, string name, int id)
    {
      return "<" + host + ">" + typePrefix + "__" + name + id.ToString ("X");
    }

    protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
    {
      base_type = Compiler.BuiltinTypes.Object;

      base_class = null;
      return null;
    }
  }

  public class HoistedStoreyClass : CompilerGeneratedContainer
  {
    public sealed class HoistedField : Field
    {
      public HoistedField (HoistedStoreyClass parent, FullNamedExpression type, Modifiers mod, string name,
          Attributes attrs, Location loc)
        : base (parent, type, mod, new MemberName (name, loc), attrs)
      {
      }

      protected override bool ResolveMemberType ()
      {
        if (!base.ResolveMemberType ())
          return false;

        HoistedStoreyClass parent = ((HoistedStoreyClass) Parent).GetGenericStorey ();
        if (parent != null && parent.Mutator != null)
          member_type = parent.Mutator.Mutate (MemberType);

        return true;
      }
    }

    protected TypeParameterMutator mutator;

    public HoistedStoreyClass (TypeDefinition parent, MemberName name, TypeParameters tparams, Modifiers mods, MemberKind kind)
      : base (parent, name, mods | Modifiers.PRIVATE, kind)
    {

      if (tparams != null) {
        var type_params = name.TypeParameters;
        var src = new TypeParameterSpec[tparams.Count];
        var dst = new TypeParameterSpec[tparams.Count];

        for (int i = 0; i < tparams.Count; ++i) {
          type_params[i] = tparams[i].CreateHoistedCopy (spec);

          src[i] = tparams[i].Type;
          dst[i] = type_params[i].Type;
        }

        // A copy is not enough, inflate any type parameter constraints
        // using a new type parameters
        var inflator = new TypeParameterInflator (this, null, src, dst);
        for (int i = 0; i < tparams.Count; ++i) {
          src[i].InflateConstraints (inflator, dst[i]);
        }

        mutator = new TypeParameterMutator (tparams, type_params);
      }
    }

    #region Properties

    public TypeParameterMutator Mutator {
      get {
        return mutator;
      }
      set {
        mutator = value;
      }
    }

    #endregion

    public HoistedStoreyClass GetGenericStorey ()
    {
      TypeContainer storey = this;
      while (storey != null && storey.CurrentTypeParameters == null)
        storey = storey.Parent;

      return storey as HoistedStoreyClass;
    }
  }


  //
  // Anonymous method storey is created when an anonymous method uses
  // variable or parameter from outer scope. They are then hoisted to
  // anonymous method storey (captured)
  //
  public class AnonymousMethodStorey : HoistedStoreyClass
  {
    struct StoreyFieldPair
    {
      public readonly AnonymousMethodStorey Storey;
      public readonly Field Field;

      public StoreyFieldPair (AnonymousMethodStorey storey, Field field)
      {
        this.Storey = storey;
        this.Field = field;
      }
    }

    //
    // Needed to delay hoisted _this_ initialization. When an anonymous
    // method is used inside ctor and _this_ is hoisted, base ctor has to
    // be called first, otherwise _this_ will be initialized with 
    // uninitialized value.
    //
    sealed class ThisInitializer : Statement
    {
      readonly HoistedThis hoisted_this;
      readonly AnonymousMethodStorey parent;

      public ThisInitializer (HoistedThis hoisted_this, AnonymousMethodStorey parent)
      {
        this.hoisted_this = hoisted_this;
        this.parent = parent;
      }

      protected override void DoEmit (EmitContext ec)
      {
        Expression source;

        if (parent == null)
          source = new CompilerGeneratedThis (ec.CurrentType, loc);
        else {
          source = new FieldExpr (parent.HoistedThis.Field, Location.Null) {
            InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, Location.Null)
          };
        }

        hoisted_this.EmitAssign (ec, source, false, false);
      }

      protected override bool DoFlowAnalysis (FlowAnalysisContext fc)
      {
        return false;
      }

      protected override void CloneTo (CloneContext clonectx, Statement target)
      {
        // Nothing to clone
      }
    }

    // Unique storey ID
    public readonly int ID;

    public readonly ExplicitBlock OriginalSourceBlock;

    // A list of StoreyFieldPair with local field keeping parent storey instance
    List<StoreyFieldPair> used_parent_storeys;
    List<ExplicitBlock> children_references;

    // A list of hoisted parameters
    protected List<HoistedParameter> hoisted_params;
    List<HoistedParameter> hoisted_local_params;
    protected List<HoistedVariable> hoisted_locals;

    // Hoisted this
    protected HoistedThis hoisted_this;

    // Local variable which holds this storey instance
    public Expression Instance;

    bool initialize_hoisted_this;
    AnonymousMethodStorey hoisted_this_parent;

    public AnonymousMethodStorey (ExplicitBlock block, TypeDefinition parent, MemberBase host, TypeParameters tparams, string name, MemberKind kind)
      : base (parent, MakeMemberName (host, name, parent.PartialContainer.CounterAnonymousContainers, tparams, block.StartLocation),
        tparams, 0, kind)
    {
      OriginalSourceBlock = block;
      ID = parent.PartialContainer.CounterAnonymousContainers++;
    }

    public void AddCapturedThisField (EmitContext ec, AnonymousMethodStorey parent)
    {
      TypeExpr type_expr = new TypeExpression (ec.CurrentType, Location);
      Field f = AddCompilerGeneratedField ("$this", type_expr);
      hoisted_this = new HoistedThis (this, f);

      initialize_hoisted_this = true;
      hoisted_this_parent = parent;
    }

    public Field AddCapturedVariable (string name, TypeSpec type)
    {
      CheckMembersDefined ();

      FullNamedExpression field_type = new TypeExpression (type, Location);
      if (!spec.IsGenericOrParentIsGeneric)
        return AddCompilerGeneratedField (name, field_type);

      const Modifiers mod = Modifiers.INTERNAL | Modifiers.COMPILER_GENERATED;
      Field f = new HoistedField (this, field_type, mod, name, null, Location);
      AddField (f);
      return f;
    }

    protected Field AddCompilerGeneratedField (string name, FullNamedExpression type)
    {
      return AddCompilerGeneratedField (name, type, false);
    }

    protected Field AddCompilerGeneratedField (string name, FullNamedExpression type, bool privateAccess)
    {
      Modifiers mod = Modifiers.COMPILER_GENERATED | (privateAccess ? Modifiers.PRIVATE : Modifiers.INTERNAL);
      Field f = new Field (this, type, mod, new MemberName (name, Location), null);
      AddField (f);
      return f;
    }

    //
    // Creates a link between hoisted variable block and the anonymous method storey
    //
    // An anonymous method can reference variables from any outer block, but they are
    // hoisted in their own ExplicitBlock. When more than one block is referenced we
    // need to create another link between those variable storeys
    //
    public void AddReferenceFromChildrenBlock (ExplicitBlock block)
    {
      if (children_references == null)
        children_references = new List<ExplicitBlock> ();

      if (!children_references.Contains (block))
        children_references.Add (block);
    }

    public void AddParentStoreyReference (EmitContext ec, AnonymousMethodStorey storey)
    {
      CheckMembersDefined ();

      if (used_parent_storeys == null)
        used_parent_storeys = new List<StoreyFieldPair> ();
      else if (used_parent_storeys.Exists (i => i.Storey == storey))
        return;

      TypeExpr type_expr = storey.CreateStoreyTypeExpression (ec);
      Field f = AddCompilerGeneratedField ("<>f__ref$" + storey.ID, type_expr);
      used_parent_storeys.Add (new StoreyFieldPair (storey, f));
    }

    public void CaptureLocalVariable (ResolveContext ec, LocalVariable localVariable)
    {
      if (this is StateMachine) {
        if (ec.CurrentBlock.ParametersBlock != localVariable.Block.ParametersBlock)
          ec.CurrentBlock.Explicit.HasCapturedVariable = true;
      } else {
        ec.CurrentBlock.Explicit.HasCapturedVariable = true;
      }

      var hoisted = localVariable.HoistedVariant;
      if (hoisted != null && hoisted.Storey != this && hoisted.Storey is StateMachine) {
        //
        // Variable is already hoisted but we need it in storey which can be shared
        //
        hoisted.Storey.hoisted_locals.Remove (hoisted);
        hoisted.Storey.Members.Remove (hoisted.Field);
        hoisted = null;
      }

      if (hoisted == null) {
        hoisted = new HoistedLocalVariable (this, localVariable, GetVariableMangledName (localVariable));
        localVariable.HoistedVariant = hoisted;

        if (hoisted_locals == null)
          hoisted_locals = new List<HoistedVariable> ();

        hoisted_locals.Add (hoisted);
      }

      if (ec.CurrentBlock.Explicit != localVariable.Block.Explicit && !(hoisted.Storey is StateMachine))
        hoisted.Storey.AddReferenceFromChildrenBlock (ec.CurrentBlock.Explicit);
    }

    public void CaptureParameter (ResolveContext ec, ParametersBlock.ParameterInfo parameterInfo, ParameterReference parameterReference)
    {
      if (!(this is StateMachine)) {
        ec.CurrentBlock.Explicit.HasCapturedVariable = true;
      }

      var hoisted = parameterInfo.Parameter.HoistedVariant;

      if (parameterInfo.Block.StateMachine != null) {
        //
        // Another storey in same block exists but state machine does not
        // have parameter captured. We need to add it there as well to
        // proxy parameter value correctly.
        //
        if (hoisted == null && parameterInfo.Block.StateMachine != this) {
          var storey = parameterInfo.Block.StateMachine;

          hoisted = new HoistedParameter (storey, parameterReference);
          parameterInfo.Parameter.HoistedVariant = hoisted;

          if (storey.hoisted_params == null)
            storey.hoisted_params = new List<HoistedParameter> ();

          storey.hoisted_params.Add (hoisted);
        }

        //
        // Lift captured parameter from value type storey to reference type one. Otherwise
        // any side effects would be done on a copy
        //
        if (hoisted != null && hoisted.Storey != this && hoisted.Storey is StateMachine) {
          if (hoisted_local_params == null)
            hoisted_local_params = new List<HoistedParameter> ();

          hoisted_local_params.Add (hoisted);
          hoisted = null;
        }
      }

      if (hoisted == null) {
        hoisted = new HoistedParameter (this, parameterReference);
        parameterInfo.Parameter.HoistedVariant = hoisted;

        if (hoisted_params == null)
          hoisted_params = new List<HoistedParameter> ();

        hoisted_params.Add (hoisted);
      }

      //
      // Register link between current block and parameter storey. It will
      // be used when setting up storey definition to deploy storey reference
      // when parameters are used from multiple blocks
      //
      if (ec.CurrentBlock.Explicit != parameterInfo.Block) {
        hoisted.Storey.AddReferenceFromChildrenBlock (ec.CurrentBlock.Explicit);
      }
    }

    TypeExpr CreateStoreyTypeExpression (EmitContext ec)
    {
      //
      // Create an instance of storey type
      //
      TypeExpr storey_type_expr;
      if (CurrentTypeParameters != null) {
        //
        // Use current method type parameter (MVAR) for top level storey only. All
        // nested storeys use class type parameter (VAR)
        //
        var tparams = ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.Storey != null ?
          ec.CurrentAnonymousMethod.Storey.CurrentTypeParameters :
          ec.CurrentTypeParameters;

        TypeArguments targs = new TypeArguments ();

        //
        // Use type parameter name instead of resolved type parameter
        // specification to resolve to correctly nested type parameters
        //
        for (int i = 0; i < tparams.Count; ++i)
          targs.Add (new SimpleName (tparams [i].Name, Location)); //  new TypeParameterExpr (tparams[i], Location));

        storey_type_expr = new GenericTypeExpr (Definition, targs, Location);
      } else {
        storey_type_expr = new TypeExpression (CurrentType, Location);
      }

      return storey_type_expr;
    }

    public void SetNestedStoryParent (AnonymousMethodStorey parentStorey)
    {
      Parent = parentStorey;
      spec.IsGeneric = false;
      spec.DeclaringType = parentStorey.CurrentType;
      MemberName.TypeParameters = null;
    }

    protected override bool DoResolveTypeParameters ()
    {
      // Although any storey can have type parameters they are all clones of method type
      // parameters therefore have to mutate MVAR references in any of cloned constraints
      if (CurrentTypeParameters != null) {
        for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
          var spec = CurrentTypeParameters[i].Type;
          spec.BaseType = mutator.Mutate (spec.BaseType);
          if (spec.InterfacesDefined != null) {
            var mutated = new TypeSpec[spec.InterfacesDefined.Length];
            for (int ii = 0; ii < mutated.Length; ++ii) {
              mutated[ii] = mutator.Mutate (spec.InterfacesDefined[ii]);
            }

            spec.InterfacesDefined = mutated;
          }

          if (spec.TypeArguments != null) {
            spec.TypeArguments = mutator.Mutate (spec.TypeArguments);
          }
        }
      }

      //
      // Update parent cache as we most likely passed the point
      // where the cache was constructed
      //
      Parent.CurrentType.MemberCache.AddMember (this.spec);

      return true;
    }

    //
    // Initializes all hoisted variables
    //
    public void EmitStoreyInstantiation (EmitContext ec, ExplicitBlock block)
    {
      // There can be only one instance variable for each storey type
      if (Instance != null)
        throw new InternalErrorException ();

      //
      // Create an instance of this storey
      //
      ResolveContext rc = new ResolveContext (ec.MemberContext);
      rc.CurrentBlock = block;

      var storey_type_expr = CreateStoreyTypeExpression (ec);
      var source = new New (storey_type_expr, null, Location).Resolve (rc);

      //
      // When the current context is async (or iterator) lift local storey
      // instantiation to the currect storey
      //
      if (ec.CurrentAnonymousMethod is StateMachineInitializer && (block.HasYield || block.HasAwait)) {
        //
        // Unfortunately, normal capture mechanism could not be used because we are
        // too late in the pipeline and standart assign cannot be used either due to
        // recursive nature of GetStoreyInstanceExpression
        //
        var field = ec.CurrentAnonymousMethod.Storey.AddCompilerGeneratedField (
          LocalVariable.GetCompilerGeneratedName (block), storey_type_expr, true);

        field.Define ();
        field.Emit ();

        var fexpr = new FieldExpr (field, Location);
        fexpr.InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, Location);
        fexpr.EmitAssign (ec, source, false, false);
        Instance = fexpr;
      } else {
        var local = TemporaryVariableReference.Create (source.Type, block, Location);
        if (source.Type.IsStruct) {
          local.LocalInfo.CreateBuilder (ec);
        } else {
          local.EmitAssign (ec, source);
        }

        Instance = local;
      }

      EmitHoistedFieldsInitialization (rc, ec);

      // TODO: Implement properly
      //SymbolWriter.DefineScopeVariable (ID, Instance.Builder);
    }

    void EmitHoistedFieldsInitialization (ResolveContext rc, EmitContext ec)
    {
      //
      // Initialize all storey reference fields by using local or hoisted variables
      //
      if (used_parent_storeys != null) {
        foreach (StoreyFieldPair sf in used_parent_storeys) {
          //
          // Get instance expression of storey field
          //
          Expression instace_expr = GetStoreyInstanceExpression (ec);
          var fs = sf.Field.Spec;
          if (TypeManager.IsGenericType (instace_expr.Type))
            fs = MemberCache.GetMember (instace_expr.Type, fs);

          FieldExpr f_set_expr = new FieldExpr (fs, Location);
          f_set_expr.InstanceExpression = instace_expr;

          // TODO: CompilerAssign expression
          SimpleAssign a = new SimpleAssign (f_set_expr, sf.Storey.GetStoreyInstanceExpression (ec));
          if (a.Resolve (rc) != null)
            a.EmitStatement (ec);
        }
      }

      //
      // Initialize hoisted `this' only once, everywhere else will be
      // referenced indirectly
      //
      if (initialize_hoisted_this) {
        rc.CurrentBlock.AddScopeStatement (new ThisInitializer (hoisted_this, hoisted_this_parent));
      }

      //
      // Setting currect anonymous method to null blocks any further variable hoisting
      //
      AnonymousExpression ae = ec.CurrentAnonymousMethod;
      ec.CurrentAnonymousMethod = null;

      if (hoisted_params != null) {
        EmitHoistedParameters (ec, hoisted_params);
      }

      ec.CurrentAnonymousMethod = ae;
    }

    protected virtual void EmitHoistedParameters (EmitContext ec, List<HoistedParameter> hoisted)
    {
      foreach (HoistedParameter hp in hoisted) {
        if (hp == null)
          continue;

        //
        // Parameters could be proxied via local fields for value type storey
        //
        if (hoisted_local_params != null) {
          var local_param = hoisted_local_params.Find (l => l.Parameter.Parameter == hp.Parameter.Parameter);
          var source = new FieldExpr (local_param.Field, Location);
          source.InstanceExpression = new CompilerGeneratedThis (CurrentType, Location);
          hp.EmitAssign (ec, source, false, false);
          continue;
        }

        hp.EmitHoistingAssignment (ec);
      }
    }

    //
    // Returns a field which holds referenced storey instance
    //
    Field GetReferencedStoreyField (AnonymousMethodStorey storey)
    {
      if (used_parent_storeys == null)
        return null;

      foreach (StoreyFieldPair sf in used_parent_storeys) {
        if (sf.Storey == storey)
          return sf.Field;
      }

      return null;
    }

    //
    // Creates storey instance expression regardless of currect IP
    //
    public Expression GetStoreyInstanceExpression (EmitContext ec)
    {
      AnonymousExpression am = ec.CurrentAnonymousMethod;

      //
      // Access from original block -> storey
      //
      if (am == null)
        return Instance;

      //
      // Access from anonymous method implemented as a static -> storey
      //
      if (am.Storey == null)
        return Instance;

      Field f = am.Storey.GetReferencedStoreyField (this);
      if (f == null) {
        if (am.Storey == this) {
          //
          // Access from inside of same storey (S -> S)
          //
          return new CompilerGeneratedThis (CurrentType, Location);
        }

        //
        // External field access
        //
        return Instance;
      }

      //
      // Storey was cached to local field
      //
      FieldExpr f_ind = new FieldExpr (f, Location);
      f_ind.InstanceExpression = new CompilerGeneratedThis (CurrentType, Location);
      return f_ind;
    }

    protected virtual string GetVariableMangledName (LocalVariable local_info)
    {
      //
      // No need to mangle anonymous method hoisted variables cause they
      // are hoisted in their own scopes
      //
      return local_info.Name;
    }

    public HoistedThis HoistedThis {
      get {
        return hoisted_this;
      }
      set {
        hoisted_this = value;
      }
    }

    public IList<ExplicitBlock> ReferencesFromChildrenBlock {
      get { return children_references; }
    }
  }

  public abstract class HoistedVariable
  {
    //
    // Hoisted version of variable references used in expression
    // tree has to be delayed until we know its location. The variable
    // doesn't know its location until all stories are calculated
    //
    class ExpressionTreeVariableReference : Expression
    {
      readonly HoistedVariable hv;

      public ExpressionTreeVariableReference (HoistedVariable hv)
      {
        this.hv = hv;
      }

      public override bool ContainsEmitWithAwait ()
      {
        return false;
      }

      public override Expression CreateExpressionTree (ResolveContext ec)
      {
        return hv.CreateExpressionTree ();
      }

      protected override Expression DoResolve (ResolveContext ec)
      {
        eclass = ExprClass.Value;
        type = ec.Module.PredefinedTypes.Expression.Resolve ();
        return this;
      }

      public override void Emit (EmitContext ec)
      {
        ResolveContext rc = new ResolveContext (ec.MemberContext);
        Expression e = hv.GetFieldExpression (ec).CreateExpressionTree (rc, false);
        // This should never fail
        e = e.Resolve (rc);
        if (e != null)
          e.Emit (ec);
      }
    }
  
    protected readonly AnonymousMethodStorey storey;
    protected Field field;
    Dictionary<AnonymousExpression, FieldExpr> cached_inner_access; // TODO: Hashtable is too heavyweight
    FieldExpr cached_outer_access;

    protected HoistedVariable (AnonymousMethodStorey storey, string name, TypeSpec type)
      : this (storey, storey.AddCapturedVariable (name, type))
    {
    }

    protected HoistedVariable (AnonymousMethodStorey storey, Field field)
    {
      this.storey = storey;
      this.field = field;
    }

    public Field Field {
      get {
        return field;
      }
    }

    public AnonymousMethodStorey Storey {
      get {
        return storey;
      }
    }

    public void AddressOf (EmitContext ec, AddressOp mode)
    {
      GetFieldExpression (ec).AddressOf (ec, mode);
    }

    public Expression CreateExpressionTree ()
    {
      return new ExpressionTreeVariableReference (this);
    }

    public void Emit (EmitContext ec)
    {
      GetFieldExpression (ec).Emit (ec);
    }

    public Expression EmitToField (EmitContext ec)
    {
      return GetFieldExpression (ec);
    }

    //
    // Creates field access expression for hoisted variable
    //
    protected virtual FieldExpr GetFieldExpression (EmitContext ec)
    {
      if (ec.CurrentAnonymousMethod == null || ec.CurrentAnonymousMethod.Storey == null) {
        if (cached_outer_access != null)
          return cached_outer_access;

        //
        // When setting top-level hoisted variable in generic storey
        // change storey generic types to method generic types (VAR -> MVAR)
        //
        if (storey.Instance.Type.IsGenericOrParentIsGeneric) {
          var fs = MemberCache.GetMember (storey.Instance.Type, field.Spec);
          cached_outer_access = new FieldExpr (fs, field.Location);
        } else {
          cached_outer_access = new FieldExpr (field, field.Location);
        }

        cached_outer_access.InstanceExpression = storey.GetStoreyInstanceExpression (ec);
        return cached_outer_access;
      }

      FieldExpr inner_access;
      if (cached_inner_access != null) {
        if (!cached_inner_access.TryGetValue (ec.CurrentAnonymousMethod, out inner_access))
          inner_access = null;
      } else {
        inner_access = null;
        cached_inner_access = new Dictionary<AnonymousExpression, FieldExpr> (4);
      }

      if (inner_access == null) {
        if (field.Parent.IsGenericOrParentIsGeneric) {
          var fs = MemberCache.GetMember (field.Parent.CurrentType, field.Spec);
          inner_access = new FieldExpr (fs, field.Location);
        } else {
          inner_access = new FieldExpr (field, field.Location);
        }

        inner_access.InstanceExpression = storey.GetStoreyInstanceExpression (ec);
        cached_inner_access.Add (ec.CurrentAnonymousMethod, inner_access);
      }

      return inner_access;
    }

    public void Emit (EmitContext ec, bool leave_copy)
    {
      GetFieldExpression (ec).Emit (ec, leave_copy);
    }

    public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
    {
      GetFieldExpression (ec).EmitAssign (ec, source, leave_copy, false);
    }
  }

  public class HoistedParameter : HoistedVariable
  {
    sealed class HoistedFieldAssign : CompilerAssign
    {
      public HoistedFieldAssign (Expression target, Expression source)
        : base (target, source, target.Location)
      {
      }

      protected override Expression ResolveConversions (ResolveContext ec)
      {
        //
        // Implicit conversion check fails for hoisted type arguments
        // as they are of different types (!!0 x !0)
        //
        return this;
      }
    }

    readonly ParameterReference parameter;

    public HoistedParameter (AnonymousMethodStorey scope, ParameterReference par)
      : base (scope, par.Name, par.Type)
    {
      this.parameter = par;
    }

    public HoistedParameter (HoistedParameter hp, string name)
      : base (hp.storey, name, hp.parameter.Type)
    {
      this.parameter = hp.parameter;
    }

    #region Properties

    public bool IsAssigned { get; set; }

    public ParameterReference Parameter {
      get {
        return parameter;
      }
    }

    #endregion

    public void EmitHoistingAssignment (EmitContext ec)
    {
      //
      // Remove hoisted redirection to emit assignment from original parameter
      //
      var temp = parameter.Parameter.HoistedVariant;
      parameter.Parameter.HoistedVariant = null;

      var a = new HoistedFieldAssign (GetFieldExpression (ec), parameter);
      a.EmitStatement (ec);

      parameter.Parameter.HoistedVariant = temp;
    }
  }

  class HoistedLocalVariable : HoistedVariable
  {
    public HoistedLocalVariable (AnonymousMethodStorey storey, LocalVariable local, string name)
      : base (storey, name, local.Type)
    {
    }
  }

  public class HoistedThis : HoistedVariable
  {
    public HoistedThis (AnonymousMethodStorey storey, Field field)
      : base (storey, field)
    {
    }
  }

  //
  // Anonymous method expression as created by parser
  //
  public class AnonymousMethodExpression : Expression
  {
    //
    // Special conversion for nested expression tree lambdas
    //
    class Quote : ShimExpression
    {
      public Quote (Expression expr)
        : base (expr)
      {
      }

      public override Expression CreateExpressionTree (ResolveContext ec)
      {
        var args = new Arguments (1);
        args.Add (new Argument (expr.CreateExpressionTree (ec)));
        return CreateExpressionFactoryCall (ec, "Quote", args);
      }

      protected override Expression DoResolve (ResolveContext rc)
      {
        expr = expr.Resolve (rc);
        if (expr == null)
          return null;

        eclass = expr.eclass;
        type = expr.Type;
        return this;
      }
    }

    readonly Dictionary<TypeSpec, Expression> compatibles;

    public ParametersBlock Block;

    public AnonymousMethodExpression (Location loc)
    {
      this.loc = loc;
      this.compatibles = new Dictionary<TypeSpec, Expression> ();
    }

    #region Properties

    public override string ExprClassName {
      get {
        return "anonymous method";
      }
    }

    public virtual bool HasExplicitParameters {
      get {
        return Parameters != ParametersCompiled.Undefined;
      }
    }

    public override bool IsSideEffectFree {
      get {
        return true;
      }
    }

    public ParametersCompiled Parameters {
      get {
        return Block.Parameters;
      }
    }

    public bool IsAsync {
      get;
      internal set;
    }

    public ReportPrinter TypeInferenceReportPrinter {
      get; set;
    }

    #endregion

    //
    // Returns true if the body of lambda expression can be implicitly
    // converted to the delegate of type `delegate_type'
    //
    public bool ImplicitStandardConversionExists (ResolveContext ec, TypeSpec delegate_type)
    {
      using (ec.With (ResolveContext.Options.InferReturnType, false)) {
        using (ec.Set (ResolveContext.Options.ProbingMode)) {
          var prev = ec.Report.SetPrinter (TypeInferenceReportPrinter ?? new NullReportPrinter ());

          var res = Compatible (ec, delegate_type) != null;

          ec.Report.SetPrinter (prev);

          return res;
        }
      }
    }

    TypeSpec CompatibleChecks (ResolveContext ec, TypeSpec delegate_type)
    {
      if (delegate_type.IsDelegate)
        return delegate_type;

      if (delegate_type.IsExpressionTreeType) {
        delegate_type = delegate_type.TypeArguments [0];
        if (delegate_type.IsDelegate)
          return delegate_type;

        ec.Report.Error (835, loc, "Cannot convert `{0}' to an expression tree of non-delegate type `{1}'",
          GetSignatureForError (), delegate_type.GetSignatureForError ());
        return null;
      }

      ec.Report.Error (1660, loc, "Cannot convert `{0}' to non-delegate type `{1}'",
              GetSignatureForError (), delegate_type.GetSignatureForError ());
      return null;
    }

    protected bool VerifyExplicitParameters (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegate_type, AParametersCollection parameters)
    {
      if (VerifyParameterCompatibility (ec, tic, delegate_type, parameters, ec.IsInProbingMode))
        return true;

      if (!ec.IsInProbingMode)
        ec.Report.Error (1661, loc,
          "Cannot convert `{0}' to delegate type `{1}' since there is a parameter mismatch",
          GetSignatureForError (), delegate_type.GetSignatureForError ());

      return false;
    }

    protected bool VerifyParameterCompatibility (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegate_type, AParametersCollection invoke_pd, bool ignore_errors)
    {
      if (Parameters.Count != invoke_pd.Count) {
        if (ignore_errors)
          return false;
        
        ec.Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
                delegate_type.GetSignatureForError (), Parameters.Count.ToString ());
        return false;
      }

      bool has_implicit_parameters = !HasExplicitParameters;
      bool error = false;

      for (int i = 0; i < Parameters.Count; ++i) {
        Parameter.Modifier p_mod = invoke_pd.FixedParameters [i].ModFlags;
        if (Parameters.FixedParameters [i].ModFlags != p_mod && p_mod != Parameter.Modifier.PARAMS) {
          if (ignore_errors)
            return false;
          
          if (p_mod == Parameter.Modifier.NONE)
            ec.Report.Error (1677, Parameters[i].Location, "Parameter `{0}' should not be declared with the `{1}' keyword",
                    (i + 1).ToString (), Parameter.GetModifierSignature (Parameters [i].ModFlags));
          else
            ec.Report.Error (1676, Parameters[i].Location, "Parameter `{0}' must be declared with the `{1}' keyword",
                    (i+1).ToString (), Parameter.GetModifierSignature (p_mod));
          error = true;
        }

        if (has_implicit_parameters)
          continue;

        TypeSpec type = invoke_pd.Types [i];

        if (tic != null)
          type = tic.InflateGenericArgument (ec, type);
        
        if (!TypeSpecComparer.IsEqual (type, Parameters.Types [i])) {
          if (ignore_errors)
            return false;
          
          ec.Report.Error (1678, Parameters [i].Location, "Parameter `{0}' is declared as type `{1}' but should be `{2}'",
                  (i+1).ToString (),
                  Parameters.Types [i].GetSignatureForError (),
                  invoke_pd.Types [i].GetSignatureForError ());
          error = true;
        }
      }

      return !error;
    }

    //
    // Infers type arguments based on explicit arguments
    //
    public bool ExplicitTypeInference (TypeInferenceContext type_inference, TypeSpec delegate_type)
    {
      if (!HasExplicitParameters)
        return false;

      if (!delegate_type.IsDelegate) {
        if (!delegate_type.IsExpressionTreeType)
          return false;

        delegate_type = TypeManager.GetTypeArguments (delegate_type) [0];
        if (!delegate_type.IsDelegate)
          return false;
      }
      
      AParametersCollection d_params = Delegate.GetParameters (delegate_type);
      if (d_params.Count != Parameters.Count)
        return false;

      var ptypes = Parameters.Types;
      var dtypes = d_params.Types;
      for (int i = 0; i < Parameters.Count; ++i) {
        if (type_inference.ExactInference (ptypes[i], dtypes[i]) == 0) {
          //
          // Continue when 0 (quick path) does not mean inference failure. Checking for
          // same type handles cases like int -> int
          //
          if (ptypes[i] == dtypes[i])
            continue;

          return false;
        }
      }

      return true;
    }

    public TypeSpec InferReturnType (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegate_type)
    {
      Expression expr;
      AnonymousExpression am;

      if (compatibles.TryGetValue (delegate_type, out expr)) {
        am = expr as AnonymousExpression;
        return am == null ? null : am.ReturnType;
      }

      using (ec.Set (ResolveContext.Options.ProbingMode | ResolveContext.Options.InferReturnType)) {
        ReportPrinter prev;
        if (TypeInferenceReportPrinter != null) {
          prev = ec.Report.SetPrinter (TypeInferenceReportPrinter);
        } else {
          prev = null;
        }

        var body = CompatibleMethodBody (ec, tic, null, delegate_type);
        if (body != null) {
          am = body.Compatible (ec, body);
        } else {
          am = null;
        }

        if (TypeInferenceReportPrinter != null) {
          ec.Report.SetPrinter (prev);
        }
      }

      if (am == null)
        return null;

//      compatibles.Add (delegate_type, am);
      return am.ReturnType;
    }

    public override bool ContainsEmitWithAwait ()
    {
      return false;
    }

    //
    // Returns AnonymousMethod container if this anonymous method
    // expression can be implicitly converted to the delegate type `delegate_type'
    //
    public Expression Compatible (ResolveContext ec, TypeSpec type)
    {
      Expression am;
      if (compatibles.TryGetValue (type, out am))
        return am;

      TypeSpec delegate_type = CompatibleChecks (ec, type);
      if (delegate_type == null)
        return null;

      //
      // At this point its the first time we know the return type that is 
      // needed for the anonymous method.  We create the method here.
      //

      var invoke_mb = Delegate.GetInvokeMethod (delegate_type);
      TypeSpec return_type = invoke_mb.ReturnType;

      //
      // Second: the return type of the delegate must be compatible with 
      // the anonymous type.   Instead of doing a pass to examine the block
      // we satisfy the rule by setting the return type on the EmitContext
      // to be the delegate type return type.
      //

      var body = CompatibleMethodBody (ec, null, return_type, delegate_type);
      if (body == null)
        return null;

      bool etree_conversion = delegate_type != type;

      try {
        if (etree_conversion) {
          if (ec.HasSet (ResolveContext.Options.ExpressionTreeConversion)) {
            //
            // Nested expression tree lambda use same scope as parent
            // lambda, this also means no variable capturing between this
            // and parent scope
            //
            am = body.Compatible (ec, ec.CurrentAnonymousMethod);

            //
            // Quote nested expression tree
            //
            if (am != null)
              am = new Quote (am);
          } else {
            int errors = ec.Report.Errors;

            if (Block.IsAsync) {
              ec.Report.Error (1989, loc, "Async lambda expressions cannot be converted to expression trees");
            }

            using (ec.Set (ResolveContext.Options.ExpressionTreeConversion)) {
              am = body.Compatible (ec);
            }

            //
            // Rewrite expressions into expression tree when targeting Expression<T>
            //
            if (am != null && errors == ec.Report.Errors)
              am = CreateExpressionTree (ec, delegate_type);
          }
        } else {
          am = body.Compatible (ec);

          if (body.DirectMethodGroupConversion != null) {
            var errors_printer = new SessionReportPrinter ();
            var old = ec.Report.SetPrinter (errors_printer);
            var expr = new ImplicitDelegateCreation (delegate_type, body.DirectMethodGroupConversion, loc) {
              AllowSpecialMethodsInvocation = true
            }.Resolve (ec);
            ec.Report.SetPrinter (old);
            if (expr != null && errors_printer.ErrorsCount == 0)
              am = expr;
          }
        }
      } catch (CompletionResult) {
        throw;
      } catch (FatalException) {
        throw;
      } catch (Exception e) {
        throw new InternalErrorException (e, loc);
      }

      if (!ec.IsInProbingMode && !etree_conversion) {
        compatibles.Add (type, am ?? EmptyExpression.Null);
      }

      return am;
    }

    protected virtual Expression CreateExpressionTree (ResolveContext ec, TypeSpec delegate_type)
    {
      return CreateExpressionTree (ec);
    }

    public override Expression CreateExpressionTree (ResolveContext ec)
    {
      ec.Report.Error (1946, loc, "An anonymous method cannot be converted to an expression tree");
      return null;
    }

    protected virtual ParametersCompiled ResolveParameters (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegate_type)
    {
      var delegate_parameters = Delegate.GetParameters (delegate_type);

      if (Parameters == ParametersCompiled.Undefined) {
        //
        // We provide a set of inaccessible parameters
        //
        Parameter[] fixedpars = new Parameter[delegate_parameters.Count];

        for (int i = 0; i < delegate_parameters.Count; i++) {
          Parameter.Modifier i_mod = delegate_parameters.FixedParameters [i].ModFlags;
          if ((i_mod & Parameter.Modifier.OUT) != 0) {
            if (!ec.IsInProbingMode) {
              ec.Report.Error (1688, loc,
                "Cannot convert anonymous method block without a parameter list to delegate type `{0}' because it has one or more `out' parameters",
                delegate_type.GetSignatureForError ());
            }

            return null;
          }
          fixedpars[i] = new Parameter (
            new TypeExpression (delegate_parameters.Types [i], loc), null,
            delegate_parameters.FixedParameters [i].ModFlags, null, loc);
        }

        return ParametersCompiled.CreateFullyResolved (fixedpars, delegate_parameters.Types);
      }

      if (!VerifyExplicitParameters (ec, tic, delegate_type, delegate_parameters)) {
        return null;
      }

      return Parameters;
    }

    protected override Expression DoResolve (ResolveContext rc)
    {
      if (rc.HasSet (ResolveContext.Options.ConstantScope)) {
        rc.Report.Error (1706, loc, "Anonymous methods and lambda expressions cannot be used in the current context");
        return null;
      }

      //
      // Update top-level block generated duting parsing with actual top-level block
      //
      if (rc.HasAny (ResolveContext.Options.FieldInitializerScope | ResolveContext.Options.BaseInitializer) && rc.CurrentMemberDefinition.Parent.PartialContainer.PrimaryConstructorParameters != null) {
        var tb = rc.ConstructorBlock.ParametersBlock.TopBlock;
        if (Block.TopBlock != tb) {
          Block b = Block;
          while (b.Parent != Block.TopBlock && b != Block.TopBlock)
            b = b.Parent;

          b.Parent = tb;
          tb.IncludeBlock (Block, Block.TopBlock);
          b.ParametersBlock.TopBlock = tb;
        }
      }

      eclass = ExprClass.Value;

      //
      // This hack means `The type is not accessible
      // anywhere', we depend on special conversion
      // rules.
      // 
      type = InternalType.AnonymousMethod;

      if (!DoResolveParameters (rc))
        return null;

      return this;
    }

    protected virtual bool DoResolveParameters (ResolveContext rc)
    {
      return Parameters.Resolve (rc);
    }

    public override void Emit (EmitContext ec)
    {
      // nothing, as we only exist to not do anything.
    }

    public static void Error_AddressOfCapturedVar (ResolveContext rc, IVariableReference var, Location loc)
    {
      if (rc.CurrentAnonymousMethod is AsyncInitializer)
        return;

      rc.Report.Error (1686, loc,
        "Local variable or parameter `{0}' cannot have their address taken and be used inside an anonymous method, lambda expression or query expression",
        var.Name);
    }

    public override string GetSignatureForError ()
    {
      return ExprClassName;
    }

    AnonymousMethodBody CompatibleMethodBody (ResolveContext ec, TypeInferenceContext tic, TypeSpec return_type, TypeSpec delegate_type)
    {
      ParametersCompiled p = ResolveParameters (ec, tic, delegate_type);
      if (p == null)
        return null;

      ParametersBlock b = ec.IsInProbingMode ? (ParametersBlock) Block.PerformClone () : Block;

      if (b.IsAsync) {
        var rt = return_type;
        if (rt != null && rt.Kind != MemberKind.Void && rt != ec.Module.PredefinedTypes.Task.TypeSpec && !rt.IsGenericTask) {
          ec.Report.Error (4010, loc, "Cannot convert async {0} to delegate type `{1}'",
            GetSignatureForError (), delegate_type.GetSignatureForError ());

          return null;
        }

        b = b.ConvertToAsyncTask (ec, ec.CurrentMemberDefinition.Parent.PartialContainer, p, return_type, delegate_type, loc);
      }

      return CompatibleMethodFactory (return_type ?? InternalType.ErrorType, delegate_type, p, b);
    }

    protected virtual AnonymousMethodBody CompatibleMethodFactory (TypeSpec return_type, TypeSpec delegate_type, ParametersCompiled p, ParametersBlock b)
    {
      return new AnonymousMethodBody (p, b, return_type, delegate_type, loc);
    }

    protected override void CloneTo (CloneContext clonectx, Expression t)
    {
      AnonymousMethodExpression target = (AnonymousMethodExpression) t;

      target.Block = (ParametersBlock) clonectx.LookupBlock (Block);
    }
    
    public override object Accept (StructuralVisitor visitor)
    {
      return visitor.Visit (this);
    }
  }

  //
  // Abstract expression for any block which requires variables hoisting
  //
  public abstract class AnonymousExpression : ExpressionStatement
  {
    protected class AnonymousMethodMethod : Method
    {
      public readonly AnonymousExpression AnonymousMethod;
      public readonly AnonymousMethodStorey Storey;

      public AnonymousMethodMethod (TypeDefinition parent, AnonymousExpression am, AnonymousMethodStorey storey,
                TypeExpr return_type,
                Modifiers mod, MemberName name,
                ParametersCompiled parameters)
        : base (parent, return_type, mod | Modifiers.COMPILER_GENERATED,
            name, parameters, null)
      {
        this.AnonymousMethod = am;
        this.Storey = storey;

        Parent.PartialContainer.Members.Add (this);
        Block = new ToplevelBlock (am.block, parameters);
      }

      public override EmitContext CreateEmitContext (ILGenerator ig, SourceMethodBuilder sourceMethod)
      {
        EmitContext ec = new EmitContext (this, ig, ReturnType, sourceMethod);
        ec.CurrentAnonymousMethod = AnonymousMethod;
        return ec;
      }

      protected override void DefineTypeParameters ()
      {
        // Type parameters were cloned
      }

      protected override bool ResolveMemberType ()
      {
        if (!base.ResolveMemberType ())
          return false;

        if (Storey != null && Storey.Mutator != null) {
          if (!parameters.IsEmpty) {
            var mutated = Storey.Mutator.Mutate (parameters.Types);
            if (mutated != parameters.Types)
              parameters = ParametersCompiled.CreateFullyResolved ((Parameter[]) parameters.FixedParameters, mutated);
          }

          member_type = Storey.Mutator.Mutate (member_type);
        }

        return true;
      }

      public override void Emit ()
      {
        if (MethodBuilder == null) {
          Define ();
        }

        base.Emit ();
      }
    }

    protected readonly ParametersBlock block;

    public TypeSpec ReturnType;

    protected AnonymousExpression (ParametersBlock block, TypeSpec return_type, Location loc)
    {
      this.ReturnType = return_type;
      this.block = block;
      this.loc = loc;
    }

    public abstract string ContainerType { get; }
    public abstract bool IsIterator { get; }
    public abstract AnonymousMethodStorey Storey { get; }

    //
    // The block that makes up the body for the anonymous method
    //
    public ParametersBlock Block {
      get {
        return block;
      }
    }

    public AnonymousExpression Compatible (ResolveContext ec)
    {
      return Compatible (ec, this);
    }

    public AnonymousExpression Compatible (ResolveContext ec, AnonymousExpression ae)
    {
      if (block.Resolved)
        return this;

      // TODO: Implement clone
      BlockContext aec = new BlockContext (ec, block, ReturnType);
      aec.CurrentAnonymousMethod = ae;

      var am = this as AnonymousMethodBody;

      if (ec.HasSet (ResolveContext.Options.InferReturnType) && am != null) {
        am.ReturnTypeInference = new TypeInferenceContext ();
      }

      var bc = ec as BlockContext;

      if (bc != null) {
        aec.AssignmentInfoOffset = bc.AssignmentInfoOffset;
        aec.EnclosingLoop = bc.EnclosingLoop;
        aec.EnclosingLoopOrSwitch = bc.EnclosingLoopOrSwitch;
        aec.Switch = bc.Switch;
      }

      var errors = ec.Report.Errors;

      bool res = Block.Resolve (aec);

      if (res && errors == ec.Report.Errors) {
        MarkReachable (new Reachability ());

        if (!CheckReachableExit (ec.Report)) {
          return null;
        }

        if (bc != null)
          bc.AssignmentInfoOffset = aec.AssignmentInfoOffset;
      }

      if (am != null && am.ReturnTypeInference != null) {
        am.ReturnTypeInference.FixAllTypes (ec);
        ReturnType = am.ReturnTypeInference.InferredTypeArguments [0];
        am.ReturnTypeInference = null;

        //
        // If e is synchronous the inferred return type is T
        // If e is asynchronous and the body of F is either an expression classified as nothing
        // or a statement block where no return statements have expressions, the inferred return type is Task
        // If e is async and has an inferred result type T, the inferred return type is Task<T>
        //
        if (block.IsAsync && ReturnType != null) {
          ReturnType = ReturnType.Kind == MemberKind.Void ?
            ec.Module.PredefinedTypes.Task.TypeSpec :
            ec.Module.PredefinedTypes.TaskGeneric.TypeSpec.MakeGenericType (ec, new [] { ReturnType });
        }
      }

      if (res && errors != ec.Report.Errors)
        return null;

      return res ? this : null;
    }

    public override bool ContainsEmitWithAwait ()
    {
      return false;
    }

    bool CheckReachableExit (Report report)
    {
      if (block.HasReachableClosingBrace && ReturnType.Kind != MemberKind.Void) {
        // FIXME: Flow-analysis on MoveNext generated code
        if (!IsIterator) {
          report.Error (1643, StartLocation,
              "Not all code paths return a value in anonymous method of type `{0}'", GetSignatureForError ());

          return false;
        }
      }

      return true;
    }

    public override void FlowAnalysis (FlowAnalysisContext fc)
    {
      // We are reachable, mark block body reachable too
      MarkReachable (new Reachability ());

      CheckReachableExit (fc.Report);

      var das = fc.BranchDefiniteAssignment ();
      var prev_pb = fc.ParametersBlock;
      fc.ParametersBlock = Block;
      var da_ontrue = fc.DefiniteAssignmentOnTrue;
      var da_onfalse = fc.DefiniteAssignmentOnFalse;

      fc.DefiniteAssignmentOnTrue = fc.DefiniteAssignmentOnFalse = null;
      block.FlowAnalysis (fc);

      fc.ParametersBlock = prev_pb;
      fc.DefiniteAssignment = das;
      fc.DefiniteAssignmentOnTrue = da_ontrue;
      fc.DefiniteAssignmentOnFalse = da_onfalse;
    }

    public override void MarkReachable (Reachability rc)
    {
      block.MarkReachable (rc);
    }

    public void SetHasThisAccess ()
    {
      ExplicitBlock b = block;
      do {
        if (b.HasCapturedThis)
          return;

        b.HasCapturedThis = true;
        b = b.Parent == null ? null : b.Parent.Explicit;
      } while (b != null);
    }
  }

  public class AnonymousMethodBody : AnonymousExpression
  {
    protected readonly ParametersCompiled parameters;
    AnonymousMethodStorey storey;

    AnonymousMethodMethod method;
    Field am_cache;
    string block_name;
    TypeInferenceContext return_inference;

    public AnonymousMethodBody (ParametersCompiled parameters,
          ParametersBlock block, TypeSpec return_type, TypeSpec delegate_type,
          Location loc)
      : base (block, return_type, loc)
    {
      this.type = delegate_type;
      this.parameters = parameters;
    }

    #region Properties

    public override string ContainerType {
      get { return "anonymous method"; }
    }

    //
    // Method-group instance for lambdas which can be replaced with
    // simple method group call
    //
    public MethodGroupExpr DirectMethodGroupConversion {
      get; set;
    }

    public override bool IsIterator {
      get {
        return false;
      }
    }

    public ParametersCompiled Parameters {
      get {
        return parameters;
      }
    }

    public TypeInferenceContext ReturnTypeInference {
      get {
        return return_inference;
      }
      set {
        return_inference = value;
      }
    }

    public override AnonymousMethodStorey Storey {
      get {
        return storey;
      }
    }

    #endregion

    public override Expression CreateExpressionTree (ResolveContext ec)
    {
      ec.Report.Error (1945, loc, "An expression tree cannot contain an anonymous method expression");
      return null;
    }

    bool Define (ResolveContext ec)
    {
      if (!Block.Resolved && Compatible (ec) == null)
        return false;

      if (block_name == null) {
        MemberCore mc = (MemberCore) ec.MemberContext;
        block_name = mc.MemberName.Basename;
      }

      return true;
    }

    //
    // Creates a host for the anonymous method
    //
    AnonymousMethodMethod DoCreateMethodHost (EmitContext ec)
    {
      //
      // Anonymous method body can be converted to
      //
      // 1, an instance method in current scope when only `this' is hoisted
      // 2, a static method in current scope when neither `this' nor any variable is hoisted
      // 3, an instance method in compiler generated storey when any hoisted variable exists
      //

      Modifiers modifiers;
      TypeDefinition parent = null;
      TypeParameters hoisted_tparams = null;
      ParametersCompiled method_parameters = parameters;

      var src_block = Block.Original.Explicit;
      if (src_block.HasCapturedVariable || src_block.HasCapturedThis) {
        parent = storey = FindBestMethodStorey ();

        if (storey == null) {
          var top_block = src_block.ParametersBlock.TopBlock;
          var sm = top_block.StateMachine;

          if (src_block.HasCapturedThis) {
            //
            // Remove hoisted 'this' request when simple instance method is
            // enough. No hoisted variables only 'this' and don't need to
            // propagate this to value type state machine.
            //
            StateMachine sm_parent;
            var pb = src_block.ParametersBlock;
            do {
              sm_parent = pb.StateMachine;
              pb = pb.Parent == null ? null : pb.Parent.ParametersBlock;
            } while (sm_parent == null && pb != null);

            if (sm_parent == null) {
              top_block.RemoveThisReferenceFromChildrenBlock (src_block);
            } else if (sm_parent.Kind == MemberKind.Struct) {
              //
              // Special case where parent class is used to emit instance method
              // because currect storey is of value type (async host) and we cannot
              // use ldftn on non-boxed instances either to share mutated state
              //
              parent = sm_parent.Parent.PartialContainer;
              hoisted_tparams = sm_parent.OriginalTypeParameters;
            } else if (sm is IteratorStorey) {
              //
              // For iterators we can host everything in one class
              //
              parent = storey = sm;
            }
          }
        }

        modifiers = storey != null ? Modifiers.INTERNAL : Modifiers.PRIVATE;
      } else {
        if (ec.CurrentAnonymousMethod != null)
          parent = storey = ec.CurrentAnonymousMethod.Storey;

        modifiers = Modifiers.STATIC | Modifiers.PRIVATE;

        //
        // Convert generated method to closed delegate method where unused
        // this argument is generated during compilation which speeds up dispatch
        // by about 25%
        //
        method_parameters = ParametersCompiled.Prefix (method_parameters,
          new Parameter (null, null, 0, null, loc), ec.Module.Compiler.BuiltinTypes.Object);
      }

      if (storey == null && hoisted_tparams == null)
        hoisted_tparams = ec.CurrentTypeParameters;

      if (parent == null)
        parent = ec.CurrentTypeDefinition.Parent.PartialContainer;

      string name = CompilerGeneratedContainer.MakeName (parent != storey ? block_name : null,
        "m", null, parent.PartialContainer.CounterAnonymousMethods++);

      MemberName member_name;
      if (hoisted_tparams != null) {
        var type_params = new TypeParameters (hoisted_tparams.Count);
        for (int i = 0; i < hoisted_tparams.Count; ++i) {
            type_params.Add (hoisted_tparams[i].CreateHoistedCopy (null));
        }

        member_name = new MemberName (name, type_params, Location);
      } else {
        member_name = new MemberName (name, Location);
      }

      return new AnonymousMethodMethod (parent,
        this, storey, new TypeExpression (ReturnType, Location), modifiers,
        member_name, method_parameters);
    }

    protected override Expression DoResolve (ResolveContext ec)
    {
      if (!Define (ec))
        return null;

      eclass = ExprClass.Value;
      return this;
    }

    public override void Emit (EmitContext ec)
    {
      //
      // Use same anonymous method implementation for scenarios where same
      // code is used from multiple blocks, e.g. field initializers
      //
      if (method == null) {
        //
        // Delay an anonymous method definition to avoid emitting unused code
        // for unreachable blocks or expression trees
        //
        method = DoCreateMethodHost (ec);
        method.Define ();
        method.PrepareEmit ();
      }

      bool is_static = (method.ModFlags & Modifiers.STATIC) != 0;
      if (is_static && am_cache == null && !ec.IsStaticConstructor) {
        //
        // Creates a field cache to store delegate instance if it's not generic
        //
        if (!method.MemberName.IsGeneric) {
          var parent = method.Parent.PartialContainer;
          int id = parent.AnonymousMethodsCounter++;
          var cache_type = storey != null && storey.Mutator != null ? storey.Mutator.Mutate (type) : type;

          am_cache = new Field (parent, new TypeExpression (cache_type, loc),
            Modifiers.STATIC | Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED,
            new MemberName (CompilerGeneratedContainer.MakeName (null, "f", "am$cache", id), loc), null);
          am_cache.Define ();
          parent.AddField (am_cache);
        } else {
          // TODO: Implement caching of generated generic static methods
          //
          // Idea:
          //
          // Some extra class is needed to capture variable generic type
          // arguments. Maybe we could re-use anonymous types, with a unique
          // anonymous method id, but they are quite heavy.
          //
          // Consider : "() => typeof(T);"
          //
          // We need something like
          // static class Wrap<Tn, Tm, DelegateType> {
          //    public static DelegateType cache;
          // }
          //
          // We then specialize local variable to capture all generic parameters
          // and delegate type, e.g. "Wrap<Ta, Tb, DelegateTypeInst> cache;"
          //
        }
      }

      Label l_initialized = ec.DefineLabel ();

      if (am_cache != null) {
        ec.Emit (OpCodes.Ldsfld, am_cache.Spec);
        ec.Emit (OpCodes.Brtrue_S, l_initialized);
      }

      //
      // Load method delegate implementation
      //

      if (is_static) {
        ec.EmitNull ();
      } else if (storey != null) {
        Expression e = storey.GetStoreyInstanceExpression (ec).Resolve (new ResolveContext (ec.MemberContext));
        if (e != null) {
          e.Emit (ec);
        }
      } else {
        ec.EmitThis ();

        //
        // Special case for value type storey where this is not lifted but
        // droped off to parent class
        //
        if (ec.CurrentAnonymousMethod != null && ec.AsyncTaskStorey != null)
          ec.Emit (OpCodes.Ldfld, ec.AsyncTaskStorey.HoistedThis.Field.Spec);
      }

      var delegate_method = method.Spec;
      if (storey != null && storey.MemberName.IsGeneric) {
        TypeSpec t = storey.Instance.Type;

        //
        // Mutate anonymous method instance type if we are in nested
        // hoisted generic anonymous method storey
        //
        if (ec.IsAnonymousStoreyMutateRequired) {
          t = storey.Mutator.Mutate (t);
        }

        ec.Emit (OpCodes.Ldftn, TypeBuilder.GetMethod (t.GetMetaInfo (), (MethodInfo) delegate_method.GetMetaInfo ()));
      } else {
        if (delegate_method.IsGeneric) {
          TypeParameterSpec[] tparams;
          var sm = ec.CurrentAnonymousMethod == null ? null : ec.CurrentAnonymousMethod.Storey as StateMachine;
          if (sm != null && sm.OriginalTypeParameters != null) {
            tparams = sm.CurrentTypeParameters.Types;
          } else {
            tparams = method.TypeParameters;
          }

          delegate_method = delegate_method.MakeGenericMethod (ec.MemberContext, tparams);
        }

        ec.Emit (OpCodes.Ldftn, delegate_method);
      }

      var constructor_method = Delegate.GetConstructor (type);
      ec.Emit (OpCodes.Newobj, constructor_method);

      if (am_cache != null) {
        ec.Emit (OpCodes.Stsfld, am_cache.Spec);
        ec.MarkLabel (l_initialized);
        ec.Emit (OpCodes.Ldsfld, am_cache.Spec);
      }
    }

    public override void EmitStatement (EmitContext ec)
    {
      throw new NotImplementedException ();
    }

    //
    // Look for the best storey for this anonymous method
    //
    AnonymousMethodStorey FindBestMethodStorey ()
    {
      //
      // Use the nearest parent block which has a storey
      //
      for (Block b = Block.Parent; b != null; b = b.Parent) {
        AnonymousMethodStorey s = b.Explicit.AnonymousMethodStorey;
        if (s != null)
          return s;
      }
          
      return null;
    }

    public override string GetSignatureForError ()
    {
      return type.GetSignatureForError ();
    }
  }

  //
  // Anonymous type container
  //
  public class AnonymousTypeClass : CompilerGeneratedContainer
  {
    public const string ClassNamePrefix = "<>__AnonType";
    public const string SignatureForError = "anonymous type";
    
    readonly IList<AnonymousTypeParameter> parameters;

    private AnonymousTypeClass (ModuleContainer parent, MemberName name, IList<AnonymousTypeParameter> parameters, Location loc)
      : base (parent, name, parent.Evaluator != null ? Modifiers.PUBLIC : Modifiers.INTERNAL)
    {
      this.parameters = parameters;
    }

    public static AnonymousTypeClass Create (TypeContainer parent, IList<AnonymousTypeParameter> parameters, Location loc)
    {
      string name = ClassNamePrefix + parent.Module.CounterAnonymousTypes++;

      ParametersCompiled all_parameters;
      TypeParameters tparams = null;
      SimpleName[] t_args;

      if (parameters.Count == 0) {
        all_parameters = ParametersCompiled.EmptyReadOnlyParameters;
        t_args = null;
      } else {
        t_args = new SimpleName[parameters.Count];
        tparams = new TypeParameters ();
        Parameter[] ctor_params = new Parameter[parameters.Count];
        for (int i = 0; i < parameters.Count; ++i) {
          AnonymousTypeParameter p = parameters[i];
          for (int ii = 0; ii < i; ++ii) {
            if (parameters[ii].Name == p.Name) {
              parent.Compiler.Report.Error (833, parameters[ii].Location,
                "`{0}': An anonymous type cannot have multiple properties with the same name",
                  p.Name);

              p = new AnonymousTypeParameter (null, "$" + i.ToString (), p.Location);
              parameters[i] = p;
              break;
            }
          }

          t_args[i] = new SimpleName ("<" + p.Name + ">__T", p.Location);
          tparams.Add (new TypeParameter (i, new MemberName (t_args[i].Name, p.Location), null, null, Variance.None));
          ctor_params[i] = new Parameter (t_args[i], p.Name, Parameter.Modifier.NONE, null, p.Location);
        }

        all_parameters = new ParametersCompiled (ctor_params);
      }

      //
      // Create generic anonymous type host with generic arguments
      // named upon properties names
      //
      AnonymousTypeClass a_type = new AnonymousTypeClass (parent.Module, new MemberName (name, tparams, loc), parameters, loc);

      Constructor c = new Constructor (a_type, name, Modifiers.PUBLIC | Modifiers.DEBUGGER_HIDDEN,
        null, all_parameters, loc);
      c.Block = new ToplevelBlock (parent.Module.Compiler, c.ParameterInfo, loc);

      // 
      // Create fields and constructor body with field initialization
      //
      bool error = false;
      for (int i = 0; i < parameters.Count; ++i) {
        AnonymousTypeParameter p = parameters [i];

        Field f = new Field (a_type, t_args [i], Modifiers.PRIVATE | Modifiers.READONLY | Modifiers.DEBUGGER_HIDDEN,
          new MemberName ("<" + p.Name + ">", p.Location), null);

        if (!a_type.AddField (f)) {
          error = true;
          continue;
        }

        c.Block.AddStatement (new StatementExpression (
          new SimpleAssign (new MemberAccess (new This (p.Location), f.Name),
            c.Block.GetParameterReference (i, p.Location))));

        ToplevelBlock get_block = new ToplevelBlock (parent.Module.Compiler, p.Location);
        get_block.AddStatement (new Return (
          new MemberAccess (new This (p.Location), f.Name), p.Location));

        Property prop = new Property (a_type, t_args [i], Modifiers.PUBLIC,
          new MemberName (p.Name, p.Location), null);
        prop.Get = new Property.GetMethod (prop, 0, null, p.Location);
        prop.Get.Block = get_block;
        a_type.AddMember (prop);
      }

      if (error)
        return null;

      a_type.AddConstructor (c);
      return a_type;
    }
    
    protected override bool DoDefineMembers ()
    {
      if (!base.DoDefineMembers ())
        return false;

      Location loc = Location;

      var equals_parameters = ParametersCompiled.CreateFullyResolved (
        new Parameter (new TypeExpression (Compiler.BuiltinTypes.Object, loc), "obj", 0, null, loc), Compiler.BuiltinTypes.Object);

      Method equals = new Method (this, new TypeExpression (Compiler.BuiltinTypes.Bool, loc),
        Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN, new MemberName ("Equals", loc),
        equals_parameters, null);

      equals_parameters[0].Resolve (equals, 0);

      Method tostring = new Method (this, new TypeExpression (Compiler.BuiltinTypes.String, loc),
        Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN, new MemberName ("ToString", loc),
        ParametersCompiled.EmptyReadOnlyParameters, null);

      ToplevelBlock equals_block = new ToplevelBlock (Compiler, equals.ParameterInfo, loc);

      TypeExpr current_type;
      if (CurrentTypeParameters != null) {
        var targs = new TypeArguments ();
        for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
          targs.Add (new TypeParameterExpr (CurrentTypeParameters[i], Location));
        }

        current_type = new GenericTypeExpr (Definition, targs, loc);
      } else {
        current_type = new TypeExpression (Definition, loc);
      }

      var li_other = LocalVariable.CreateCompilerGenerated (CurrentType, equals_block, loc);
      equals_block.AddStatement (new BlockVariable (new TypeExpression (li_other.Type, loc), li_other));
      var other_variable = new LocalVariableReference (li_other, loc);

      MemberAccess system_collections_generic = new MemberAccess (new MemberAccess (
        new QualifiedAliasMember ("global", "System", loc), "Collections", loc), "Generic", loc);

      Expression rs_equals = null;
      Expression string_concat = new StringConstant (Compiler.BuiltinTypes, "{", loc);
      Expression rs_hashcode = new IntConstant (Compiler.BuiltinTypes, -2128831035, loc);
      for (int i = 0; i < parameters.Count; ++i) {
        var p = parameters [i];
        var f = (Field) Members [i * 2];

        MemberAccess equality_comparer = new MemberAccess (new MemberAccess (
          system_collections_generic, "EqualityComparer",
            new TypeArguments (new SimpleName (CurrentTypeParameters [i].Name, loc)), loc),
            "Default", loc);

        Arguments arguments_equal = new Arguments (2);
        arguments_equal.Add (new Argument (new MemberAccess (new This (f.Location), f.Name)));
        arguments_equal.Add (new Argument (new MemberAccess (other_variable, f.Name)));

        Expression field_equal = new Invocation (new MemberAccess (equality_comparer,
          "Equals", loc), arguments_equal);

        Arguments arguments_hashcode = new Arguments (1);
        arguments_hashcode.Add (new Argument (new MemberAccess (new This (f.Location), f.Name)));
        Expression field_hashcode = new Invocation (new MemberAccess (equality_comparer,
          "GetHashCode", loc), arguments_hashcode);

        IntConstant FNV_prime = new IntConstant (Compiler.BuiltinTypes, 16777619, loc);       
        rs_hashcode = new Binary (Binary.Operator.Multiply,
          new Binary (Binary.Operator.ExclusiveOr, rs_hashcode, field_hashcode),
          FNV_prime);

        Expression field_to_string = new Conditional (new BooleanExpression (new Binary (Binary.Operator.Inequality,
          new MemberAccess (new This (f.Location), f.Name), new NullLiteral (loc))),
          new Invocation (new MemberAccess (
            new MemberAccess (new This (f.Location), f.Name), "ToString"), null),
          new StringConstant (Compiler.BuiltinTypes, string.Empty, loc), loc);

        if (rs_equals == null) {
          rs_equals = field_equal;
          string_concat = new Binary (Binary.Operator.Addition,
            string_concat,
            new Binary (Binary.Operator.Addition,
              new StringConstant (Compiler.BuiltinTypes, " " + p.Name + " = ", loc),
              field_to_string));
          continue;
        }

        //
        // Implementation of ToString () body using string concatenation
        //        
        string_concat = new Binary (Binary.Operator.Addition,
          new Binary (Binary.Operator.Addition,
            string_concat,
            new StringConstant (Compiler.BuiltinTypes, ", " + p.Name + " = ", loc)),
          field_to_string);

        rs_equals = new Binary (Binary.Operator.LogicalAnd, rs_equals, field_equal);
      }

      string_concat = new Binary (Binary.Operator.Addition,
        string_concat,
        new StringConstant (Compiler.BuiltinTypes, " }", loc));

      //
      // Equals (object obj) override
      //    
      var other_variable_assign = new TemporaryVariableReference (li_other, loc);
      equals_block.AddStatement (new StatementExpression (
        new SimpleAssign (other_variable_assign,
          new As (equals_block.GetParameterReference (0, loc),
            current_type, loc), loc)));

      Expression equals_test = new Binary (Binary.Operator.Inequality, other_variable, new NullLiteral (loc));
      if (rs_equals != null)
        equals_test = new Binary (Binary.Operator.LogicalAnd, equals_test, rs_equals);
      equals_block.AddStatement (new Return (equals_test, loc));

      equals.Block = equals_block;
      equals.Define ();
      Members.Add (equals);

      //
      // GetHashCode () override
      //
      Method hashcode = new Method (this, new TypeExpression (Compiler.BuiltinTypes.Int, loc),
        Modifiers.PUBLIC | Modifiers.OVERRIDE | Modifiers.DEBUGGER_HIDDEN,
        new MemberName ("GetHashCode", loc),
        ParametersCompiled.EmptyReadOnlyParameters, null);

      //
      // Modified FNV with good avalanche behavior and uniform
      // distribution with larger hash sizes.
      //
      // const int FNV_prime = 16777619;
      // int hash = (int) 2166136261;
      // foreach (int d in data)
      //     hash = (hash ^ d) * FNV_prime;
      // hash += hash << 13;
      // hash ^= hash >> 7;
      // hash += hash << 3;
      // hash ^= hash >> 17;
      // hash += hash << 5;

      ToplevelBlock hashcode_top = new ToplevelBlock (Compiler, loc);
      Block hashcode_block = new Block (hashcode_top, loc, loc);
      hashcode_top.AddStatement (new Unchecked (hashcode_block, loc));

      var li_hash = LocalVariable.CreateCompilerGenerated (Compiler.BuiltinTypes.Int, hashcode_top, loc);
      hashcode_block.AddStatement (new BlockVariable (new TypeExpression (li_hash.Type, loc), li_hash));
      LocalVariableReference hash_variable_assign = new LocalVariableReference (li_hash, loc);
      hashcode_block.AddStatement (new StatementExpression (
        new SimpleAssign (hash_variable_assign, rs_hashcode)));

      var hash_variable = new LocalVariableReference (li_hash, loc);
      hashcode_block.AddStatement (new StatementExpression (
        new CompoundAssign (Binary.Operator.Addition, hash_variable,
          new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 13, loc)))));
      hashcode_block.AddStatement (new StatementExpression (
        new CompoundAssign (Binary.Operator.ExclusiveOr, hash_variable,
          new Binary (Binary.Operator.RightShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 7, loc)))));
      hashcode_block.AddStatement (new StatementExpression (
        new CompoundAssign (Binary.Operator.Addition, hash_variable,
          new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 3, loc)))));
      hashcode_block.AddStatement (new StatementExpression (
        new CompoundAssign (Binary.Operator.ExclusiveOr, hash_variable,
          new Binary (Binary.Operator.RightShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 17, loc)))));
      hashcode_block.AddStatement (new StatementExpression (
        new CompoundAssign (Binary.Operator.Addition, hash_variable,
          new Binary (Binary.Operator.LeftShift, hash_variable, new IntConstant (Compiler.BuiltinTypes, 5, loc)))));

      hashcode_block.AddStatement (new Return (hash_variable, loc));
      hashcode.Block = hashcode_top;
      hashcode.Define ();
      Members.Add (hashcode);

      //
      // ToString () override
      //

      ToplevelBlock tostring_block = new ToplevelBlock (Compiler, loc);
      tostring_block.AddStatement (new Return (string_concat, loc));
      tostring.Block = tostring_block;
      tostring.Define ();
      Members.Add (tostring);

      return true;
    }

    public override string GetSignatureForError ()
    {
      return SignatureForError;
    }

    public override CompilationSourceFile GetCompilationSourceFile ()
    {
      return null;
    }

    public IList<AnonymousTypeParameter> Parameters {
      get {
        return parameters;
      }
    }
  }
}