975 lines
24 KiB
C#
975 lines
24 KiB
C#
//
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// assign.cs: Assignments.
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//
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// Author:
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// Miguel de Icaza (miguel@ximian.com)
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// Martin Baulig (martin@ximian.com)
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// Marek Safar (marek.safar@gmail.com)
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//
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// Dual licensed under the terms of the MIT X11 or GNU GPL
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//
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// Copyright 2001, 2002, 2003 Ximian, Inc.
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// Copyright 2004-2008 Novell, Inc
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// Copyright 2011 Xamarin Inc
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//
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using System;
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#if STATIC
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using IKVM.Reflection.Emit;
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#else
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using System.Reflection.Emit;
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#endif
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namespace Mono.CSharp {
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/// <summary>
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/// This interface is implemented by expressions that can be assigned to.
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/// </summary>
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/// <remarks>
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/// This interface is implemented by Expressions whose values can not
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/// store the result on the top of the stack.
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///
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/// Expressions implementing this (Properties, Indexers and Arrays) would
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/// perform an assignment of the Expression "source" into its final
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/// location.
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///
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/// No values on the top of the stack are expected to be left by
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/// invoking this method.
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/// </remarks>
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public interface IAssignMethod {
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//
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// This is an extra version of Emit. If leave_copy is `true'
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// A copy of the expression will be left on the stack at the
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// end of the code generated for EmitAssign
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//
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void Emit (EmitContext ec, bool leave_copy);
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//
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// This method does the assignment
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// `source' will be stored into the location specified by `this'
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// if `leave_copy' is true, a copy of `source' will be left on the stack
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// if `prepare_for_load' is true, when `source' is emitted, there will
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// be data on the stack that it can use to compuatate its value. This is
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// for expressions like a [f ()] ++, where you can't call `f ()' twice.
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//
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void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound);
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/*
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For simple assignments, this interface is very simple, EmitAssign is called with source
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as the source expression and leave_copy and prepare_for_load false.
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For compound assignments it gets complicated.
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EmitAssign will be called as before, however, prepare_for_load will be
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true. The @source expression will contain an expression
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which calls Emit. So, the calls look like:
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this.EmitAssign (ec, source, false, true) ->
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source.Emit (ec); ->
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[...] ->
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this.Emit (ec, false); ->
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end this.Emit (ec, false); ->
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end [...]
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end source.Emit (ec);
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end this.EmitAssign (ec, source, false, true)
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When prepare_for_load is true, EmitAssign emits a `token' on the stack that
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Emit will use for its state.
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Let's take FieldExpr as an example. assume we are emitting f ().y += 1;
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Here is the call tree again. This time, each call is annotated with the IL
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it produces:
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this.EmitAssign (ec, source, false, true)
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call f
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dup
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Binary.Emit ()
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this.Emit (ec, false);
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ldfld y
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end this.Emit (ec, false);
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IntConstant.Emit ()
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ldc.i4.1
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end IntConstant.Emit
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add
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end Binary.Emit ()
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stfld
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end this.EmitAssign (ec, source, false, true)
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Observe two things:
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1) EmitAssign left a token on the stack. It was the result of f ().
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2) This token was used by Emit
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leave_copy (in both EmitAssign and Emit) tells the compiler to leave a copy
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of the expression at that point in evaluation. This is used for pre/post inc/dec
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and for a = x += y. Let's do the above example with leave_copy true in EmitAssign
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this.EmitAssign (ec, source, true, true)
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call f
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dup
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Binary.Emit ()
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this.Emit (ec, false);
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ldfld y
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end this.Emit (ec, false);
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IntConstant.Emit ()
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ldc.i4.1
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end IntConstant.Emit
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add
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end Binary.Emit ()
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dup
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stloc temp
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stfld
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ldloc temp
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end this.EmitAssign (ec, source, true, true)
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And with it true in Emit
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this.EmitAssign (ec, source, false, true)
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call f
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dup
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Binary.Emit ()
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this.Emit (ec, true);
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ldfld y
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dup
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stloc temp
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end this.Emit (ec, true);
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IntConstant.Emit ()
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ldc.i4.1
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end IntConstant.Emit
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add
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end Binary.Emit ()
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stfld
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ldloc temp
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end this.EmitAssign (ec, source, false, true)
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Note that these two examples are what happens for ++x and x++, respectively.
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*/
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}
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/// <summary>
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/// An Expression to hold a temporary value.
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/// </summary>
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/// <remarks>
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/// The LocalTemporary class is used to hold temporary values of a given
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/// type to "simulate" the expression semantics. The local variable is
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/// never captured.
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///
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/// The local temporary is used to alter the normal flow of code generation
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/// basically it creates a local variable, and its emit instruction generates
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/// code to access this value, return its address or save its value.
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///
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/// If `is_address' is true, then the value that we store is the address to the
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/// real value, and not the value itself.
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///
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/// This is needed for a value type, because otherwise you just end up making a
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/// copy of the value on the stack and modifying it. You really need a pointer
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/// to the origional value so that you can modify it in that location. This
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/// Does not happen with a class because a class is a pointer -- so you always
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/// get the indirection.
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///
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/// </remarks>
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public class LocalTemporary : Expression, IMemoryLocation, IAssignMethod {
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LocalBuilder builder;
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public LocalTemporary (TypeSpec t)
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{
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type = t;
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eclass = ExprClass.Value;
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}
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public LocalTemporary (LocalBuilder b, TypeSpec t)
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: this (t)
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{
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builder = b;
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}
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public void Release (EmitContext ec)
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{
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ec.FreeTemporaryLocal (builder, type);
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builder = null;
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}
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public override bool ContainsEmitWithAwait ()
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{
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return false;
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}
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public override Expression CreateExpressionTree (ResolveContext ec)
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{
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Arguments args = new Arguments (1);
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args.Add (new Argument (this));
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return CreateExpressionFactoryCall (ec, "Constant", args);
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}
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protected override Expression DoResolve (ResolveContext ec)
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{
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return this;
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}
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public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
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{
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return this;
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}
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public override void Emit (EmitContext ec)
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{
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if (builder == null)
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throw new InternalErrorException ("Emit without Store, or after Release");
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ec.Emit (OpCodes.Ldloc, builder);
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}
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#region IAssignMethod Members
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public void Emit (EmitContext ec, bool leave_copy)
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{
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Emit (ec);
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if (leave_copy)
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Emit (ec);
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}
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public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
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{
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if (isCompound)
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throw new NotImplementedException ();
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source.Emit (ec);
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Store (ec);
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if (leave_copy)
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Emit (ec);
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}
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#endregion
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public LocalBuilder Builder {
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get { return builder; }
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}
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public void Store (EmitContext ec)
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{
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if (builder == null)
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builder = ec.GetTemporaryLocal (type);
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ec.Emit (OpCodes.Stloc, builder);
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}
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public void AddressOf (EmitContext ec, AddressOp mode)
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{
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if (builder == null)
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builder = ec.GetTemporaryLocal (type);
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if (builder.LocalType.IsByRef) {
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//
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// if is_address, than this is just the address anyways,
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// so we just return this.
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//
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ec.Emit (OpCodes.Ldloc, builder);
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} else {
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ec.Emit (OpCodes.Ldloca, builder);
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}
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}
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}
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/// <summary>
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/// The Assign node takes care of assigning the value of source into
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/// the expression represented by target.
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/// </summary>
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public abstract class Assign : ExpressionStatement {
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protected Expression target, source;
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protected Assign (Expression target, Expression source, Location loc)
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{
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this.target = target;
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this.source = source;
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this.loc = loc;
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}
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public Expression Target {
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get { return target; }
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}
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public Expression Source {
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get {
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return source;
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}
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}
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public override Location StartLocation {
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get {
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return target.StartLocation;
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}
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}
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public override bool ContainsEmitWithAwait ()
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{
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return target.ContainsEmitWithAwait () || source.ContainsEmitWithAwait ();
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}
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public override Expression CreateExpressionTree (ResolveContext ec)
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{
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ec.Report.Error (832, loc, "An expression tree cannot contain an assignment operator");
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return null;
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}
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protected override Expression DoResolve (ResolveContext ec)
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{
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bool ok = true;
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source = source.Resolve (ec);
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if (source == null) {
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ok = false;
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source = ErrorExpression.Instance;
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}
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target = target.ResolveLValue (ec, source);
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if (target == null || !ok)
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return null;
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TypeSpec target_type = target.Type;
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TypeSpec source_type = source.Type;
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eclass = ExprClass.Value;
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type = target_type;
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if (!(target is IAssignMethod)) {
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target.Error_ValueAssignment (ec, source);
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return null;
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}
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if (target_type != source_type) {
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Expression resolved = ResolveConversions (ec);
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if (resolved != this)
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return resolved;
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}
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return this;
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}
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public override System.Linq.Expressions.Expression MakeExpression (BuilderContext ctx)
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{
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var tassign = target as IDynamicAssign;
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if (tassign == null)
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throw new InternalErrorException (target.GetType () + " does not support dynamic assignment");
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var target_object = tassign.MakeAssignExpression (ctx, source);
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//
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// Some hacking is needed as DLR does not support void type and requires
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// always have object convertible return type to support caching and chaining
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//
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// We do this by introducing an explicit block which returns RHS value when
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// available or null
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//
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if (target_object.NodeType == System.Linq.Expressions.ExpressionType.Block)
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return target_object;
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System.Linq.Expressions.UnaryExpression source_object;
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if (ctx.HasSet (BuilderContext.Options.CheckedScope)) {
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source_object = System.Linq.Expressions.Expression.ConvertChecked (source.MakeExpression (ctx), target_object.Type);
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} else {
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source_object = System.Linq.Expressions.Expression.Convert (source.MakeExpression (ctx), target_object.Type);
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}
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return System.Linq.Expressions.Expression.Assign (target_object, source_object);
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}
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protected virtual Expression ResolveConversions (ResolveContext rc)
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{
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var ttype = target.Type;
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var stackAlloc = source as StackAlloc;
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if (stackAlloc != null && ttype.Arity == 1 && ttype.GetDefinition () == rc.Module.PredefinedTypes.SpanGeneric.TypeSpec &&
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rc.Module.Compiler.Settings.Version >= LanguageVersion.V_7_2) {
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var etype = ttype.TypeArguments [0];
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var stype = ((PointerContainer)source.Type).Element;
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if (etype == stype && stackAlloc.ResolveSpanConversion (rc, ttype)) {
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return this;
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}
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}
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source = Convert.ImplicitConversionRequired (rc, source, ttype, source.Location);
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if (source == null)
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return null;
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return this;
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}
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void Emit (EmitContext ec, bool is_statement)
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{
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IAssignMethod t = (IAssignMethod) target;
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t.EmitAssign (ec, source, !is_statement, this is CompoundAssign);
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}
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public override void Emit (EmitContext ec)
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{
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Emit (ec, false);
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}
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public override void EmitStatement (EmitContext ec)
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{
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Emit (ec, true);
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}
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public override void FlowAnalysis (FlowAnalysisContext fc)
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{
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source.FlowAnalysis (fc);
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if (target is ArrayAccess || target is IndexerExpr) {
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target.FlowAnalysis (fc);
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return;
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}
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var pe = target as PropertyExpr;
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if (pe != null && !pe.IsAutoPropertyAccess)
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target.FlowAnalysis (fc);
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}
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protected override void CloneTo (CloneContext clonectx, Expression t)
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{
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Assign _target = (Assign) t;
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_target.target = target.Clone (clonectx);
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_target.source = source.Clone (clonectx);
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}
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public override object Accept (StructuralVisitor visitor)
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{
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return visitor.Visit (this);
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}
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}
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public class SimpleAssign : Assign
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{
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public SimpleAssign (Expression target, Expression source)
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: this (target, source, target.Location)
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{
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}
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public SimpleAssign (Expression target, Expression source, Location loc)
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: base (target, source, loc)
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{
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}
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bool CheckEqualAssign (Expression t)
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{
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if (source is Assign) {
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Assign a = (Assign) source;
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if (t.Equals (a.Target))
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return true;
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return a is SimpleAssign && ((SimpleAssign) a).CheckEqualAssign (t);
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}
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return t.Equals (source);
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}
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protected override Expression DoResolve (ResolveContext ec)
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{
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Expression e = base.DoResolve (ec);
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if (e == null || e != this)
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return e;
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if (CheckEqualAssign (target))
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ec.Report.Warning (1717, 3, loc, "Assignment made to same variable; did you mean to assign something else?");
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return this;
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}
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public override void FlowAnalysis (FlowAnalysisContext fc)
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{
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base.FlowAnalysis (fc);
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var vr = target as VariableReference;
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if (vr != null) {
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if (vr.VariableInfo != null)
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fc.SetVariableAssigned (vr.VariableInfo);
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return;
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}
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var fe = target as FieldExpr;
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if (fe != null) {
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fe.SetFieldAssigned (fc);
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return;
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}
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var pe = target as PropertyExpr;
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if (pe != null) {
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pe.SetBackingFieldAssigned (fc);
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return;
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}
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var td = target as TupleDeconstruct;
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if (td != null) {
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td.SetGeneratedFieldAssigned (fc);
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return;
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}
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}
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public override Reachability MarkReachable (Reachability rc)
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{
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return source.MarkReachable (rc);
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}
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}
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public class RuntimeExplicitAssign : Assign
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{
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public RuntimeExplicitAssign (Expression target, Expression source)
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: base (target, source, target.Location)
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{
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}
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protected override Expression ResolveConversions (ResolveContext ec)
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{
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source = EmptyCast.Create (source, target.Type);
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return this;
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}
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}
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//
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// Compiler generated assign
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//
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class CompilerAssign : Assign
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{
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public CompilerAssign (Expression target, Expression source, Location loc)
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: base (target, source, loc)
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{
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if (target.Type != null) {
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type = target.Type;
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eclass = ExprClass.Value;
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}
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}
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protected override Expression DoResolve (ResolveContext ec)
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{
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var expr = base.DoResolve (ec);
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var vr = target as VariableReference;
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if (vr != null && vr.VariableInfo != null)
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vr.VariableInfo.IsEverAssigned = false;
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return expr;
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}
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public void UpdateSource (Expression source)
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{
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base.source = source;
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}
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}
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//
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// Implements fields and events class initializers
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//
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public class FieldInitializer : Assign
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{
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//
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// Field initializers are tricky for partial classes. They have to
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// share same constructor (block) for expression trees resolve but
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// they have they own resolve scope
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//
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sealed class FieldInitializerContext : BlockContext
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{
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readonly ExplicitBlock ctor_block;
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public FieldInitializerContext (IMemberContext mc, BlockContext constructorContext)
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: base (mc, null, constructorContext.ReturnType)
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{
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flags |= Options.FieldInitializerScope | Options.ConstructorScope;
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this.ctor_block = constructorContext.CurrentBlock.Explicit;
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if (ctor_block.IsCompilerGenerated)
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CurrentBlock = ctor_block;
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}
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public override ExplicitBlock ConstructorBlock {
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get {
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return ctor_block;
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}
|
|
}
|
|
}
|
|
|
|
//
|
|
// Keep resolved value because field initializers have their own rules
|
|
//
|
|
ExpressionStatement resolved;
|
|
FieldBase mc;
|
|
|
|
public FieldInitializer (FieldBase mc, Expression expression, Location loc)
|
|
: base (new FieldExpr (mc.Spec, expression.Location), expression, loc)
|
|
{
|
|
this.mc = mc;
|
|
if (!mc.IsStatic)
|
|
((FieldExpr)target).InstanceExpression = new CompilerGeneratedThis (mc.CurrentType, expression.Location);
|
|
}
|
|
|
|
public int AssignmentOffset { get; private set; }
|
|
|
|
public FieldBase Field {
|
|
get {
|
|
return mc;
|
|
}
|
|
}
|
|
|
|
public override Location StartLocation {
|
|
get {
|
|
return loc;
|
|
}
|
|
}
|
|
|
|
protected override Expression DoResolve (ResolveContext rc)
|
|
{
|
|
// Field initializer can be resolved (fail) many times
|
|
if (source == null)
|
|
return null;
|
|
|
|
if (resolved == null) {
|
|
var bc = (BlockContext) rc;
|
|
var ctx = new FieldInitializerContext (mc, bc);
|
|
resolved = base.DoResolve (ctx) as ExpressionStatement;
|
|
AssignmentOffset = ctx.AssignmentInfoOffset - bc.AssignmentInfoOffset;
|
|
}
|
|
|
|
return resolved;
|
|
}
|
|
|
|
public override void EmitStatement (EmitContext ec)
|
|
{
|
|
if (resolved == null)
|
|
return;
|
|
|
|
//
|
|
// Emit sequence symbol info even if we are in compiler generated
|
|
// block to allow debugging field initializers when constructor is
|
|
// compiler generated
|
|
//
|
|
if (ec.HasSet (BuilderContext.Options.OmitDebugInfo) && ec.HasMethodSymbolBuilder) {
|
|
using (ec.With (BuilderContext.Options.OmitDebugInfo, false)) {
|
|
ec.Mark (loc);
|
|
}
|
|
}
|
|
|
|
if (resolved != this)
|
|
resolved.EmitStatement (ec);
|
|
else
|
|
base.EmitStatement (ec);
|
|
}
|
|
|
|
public override void FlowAnalysis (FlowAnalysisContext fc)
|
|
{
|
|
source.FlowAnalysis (fc);
|
|
((FieldExpr) target).SetFieldAssigned (fc);
|
|
}
|
|
|
|
public bool IsDefaultInitializer {
|
|
get {
|
|
Constant c = source as Constant;
|
|
if (c == null)
|
|
return false;
|
|
|
|
FieldExpr fe = (FieldExpr)target;
|
|
return c.IsDefaultInitializer (fe.Type);
|
|
}
|
|
}
|
|
|
|
public override bool IsSideEffectFree {
|
|
get {
|
|
return source.IsSideEffectFree;
|
|
}
|
|
}
|
|
}
|
|
|
|
class PrimaryConstructorAssign : SimpleAssign
|
|
{
|
|
readonly Field field;
|
|
readonly Parameter parameter;
|
|
|
|
public PrimaryConstructorAssign (Field field, Parameter parameter)
|
|
: base (null, null, parameter.Location)
|
|
{
|
|
this.field = field;
|
|
this.parameter = parameter;
|
|
}
|
|
|
|
protected override Expression DoResolve (ResolveContext rc)
|
|
{
|
|
target = new FieldExpr (field, loc);
|
|
source = rc.CurrentBlock.ParametersBlock.GetParameterInfo (parameter).CreateReferenceExpression (rc, loc);
|
|
return base.DoResolve (rc);
|
|
}
|
|
|
|
public override void EmitStatement (EmitContext ec)
|
|
{
|
|
using (ec.With (BuilderContext.Options.OmitDebugInfo, true)) {
|
|
base.EmitStatement (ec);
|
|
}
|
|
}
|
|
}
|
|
|
|
//
|
|
// This class is used for compound assignments.
|
|
//
|
|
public class CompoundAssign : Assign
|
|
{
|
|
// This is just a hack implemented for arrays only
|
|
public sealed class TargetExpression : Expression
|
|
{
|
|
readonly Expression child;
|
|
|
|
public TargetExpression (Expression child)
|
|
{
|
|
this.child = child;
|
|
this.loc = child.Location;
|
|
}
|
|
|
|
public bool RequiresEmitWithAwait { get; set; }
|
|
|
|
public override bool ContainsEmitWithAwait ()
|
|
{
|
|
return RequiresEmitWithAwait || child.ContainsEmitWithAwait ();
|
|
}
|
|
|
|
public override Expression CreateExpressionTree (ResolveContext ec)
|
|
{
|
|
throw new NotSupportedException ("ET");
|
|
}
|
|
|
|
protected override Expression DoResolve (ResolveContext ec)
|
|
{
|
|
type = child.Type;
|
|
eclass = ExprClass.Value;
|
|
return this;
|
|
}
|
|
|
|
public override void Emit (EmitContext ec)
|
|
{
|
|
child.Emit (ec);
|
|
}
|
|
|
|
public override Expression EmitToField (EmitContext ec)
|
|
{
|
|
return child.EmitToField (ec);
|
|
}
|
|
}
|
|
|
|
// Used for underlying binary operator
|
|
readonly Binary.Operator op;
|
|
Expression right;
|
|
Expression left;
|
|
|
|
public CompoundAssign (Binary.Operator op, Expression target, Expression source)
|
|
: base (target, source, target.Location)
|
|
{
|
|
right = source;
|
|
this.op = op;
|
|
}
|
|
|
|
public CompoundAssign (Binary.Operator op, Expression target, Expression source, Expression left)
|
|
: this (op, target, source)
|
|
{
|
|
this.left = left;
|
|
}
|
|
|
|
public Binary.Operator Operator {
|
|
get {
|
|
return op;
|
|
}
|
|
}
|
|
|
|
protected override Expression DoResolve (ResolveContext ec)
|
|
{
|
|
right = right.Resolve (ec);
|
|
if (right == null)
|
|
return null;
|
|
|
|
MemberAccess ma = target as MemberAccess;
|
|
using (ec.Set (ResolveContext.Options.CompoundAssignmentScope)) {
|
|
target = target.Resolve (ec);
|
|
}
|
|
|
|
if (target == null)
|
|
return null;
|
|
|
|
if (target is MethodGroupExpr){
|
|
ec.Report.Error (1656, loc,
|
|
"Cannot assign to `{0}' because it is a `{1}'",
|
|
((MethodGroupExpr)target).Name, target.ExprClassName);
|
|
return null;
|
|
}
|
|
|
|
var event_expr = target as EventExpr;
|
|
if (event_expr != null) {
|
|
source = Convert.ImplicitConversionRequired (ec, right, target.Type, loc);
|
|
if (source == null)
|
|
return null;
|
|
|
|
Expression rside;
|
|
if (op == Binary.Operator.Addition)
|
|
rside = EmptyExpression.EventAddition;
|
|
else if (op == Binary.Operator.Subtraction)
|
|
rside = EmptyExpression.EventSubtraction;
|
|
else
|
|
rside = null;
|
|
|
|
target = target.ResolveLValue (ec, rside);
|
|
if (target == null)
|
|
return null;
|
|
|
|
eclass = ExprClass.Value;
|
|
type = event_expr.Operator.ReturnType;
|
|
return this;
|
|
}
|
|
|
|
//
|
|
// Only now we can decouple the original source/target
|
|
// into a tree, to guarantee that we do not have side
|
|
// effects.
|
|
//
|
|
if (left == null)
|
|
left = new TargetExpression (target);
|
|
|
|
source = new Binary (op, left, right, true);
|
|
|
|
if (target is DynamicMemberAssignable) {
|
|
Arguments targs = ((DynamicMemberAssignable) target).Arguments;
|
|
source = source.Resolve (ec);
|
|
|
|
Arguments args = new Arguments (targs.Count + 1);
|
|
args.AddRange (targs);
|
|
args.Add (new Argument (source));
|
|
|
|
var binder_flags = CSharpBinderFlags.ValueFromCompoundAssignment;
|
|
|
|
//
|
|
// Compound assignment does target conversion using additional method
|
|
// call, set checked context as the binary operation can overflow
|
|
//
|
|
if (ec.HasSet (ResolveContext.Options.CheckedScope))
|
|
binder_flags |= CSharpBinderFlags.CheckedContext;
|
|
|
|
if (target is DynamicMemberBinder) {
|
|
source = new DynamicMemberBinder (ma.Name, binder_flags, args, loc).Resolve (ec);
|
|
|
|
// Handles possible event addition/subtraction
|
|
if (op == Binary.Operator.Addition || op == Binary.Operator.Subtraction) {
|
|
args = new Arguments (targs.Count + 1);
|
|
args.AddRange (targs);
|
|
args.Add (new Argument (right));
|
|
string method_prefix = op == Binary.Operator.Addition ?
|
|
Event.AEventAccessor.AddPrefix : Event.AEventAccessor.RemovePrefix;
|
|
|
|
var invoke = DynamicInvocation.CreateSpecialNameInvoke (
|
|
new MemberAccess (right, method_prefix + ma.Name, loc), args, loc).Resolve (ec);
|
|
|
|
args = new Arguments (targs.Count);
|
|
args.AddRange (targs);
|
|
source = new DynamicEventCompoundAssign (ma.Name, args,
|
|
(ExpressionStatement) source, (ExpressionStatement) invoke, loc).Resolve (ec);
|
|
}
|
|
} else {
|
|
source = new DynamicIndexBinder (binder_flags, args, loc).Resolve (ec);
|
|
}
|
|
|
|
return source;
|
|
}
|
|
|
|
return base.DoResolve (ec);
|
|
}
|
|
|
|
public override void FlowAnalysis (FlowAnalysisContext fc)
|
|
{
|
|
target.FlowAnalysis (fc);
|
|
source.FlowAnalysis (fc);
|
|
}
|
|
|
|
protected override Expression ResolveConversions (ResolveContext ec)
|
|
{
|
|
//
|
|
// LAMESPEC: Under dynamic context no target conversion is happening
|
|
// This allows more natual dynamic behaviour but breaks compatibility
|
|
// with static binding
|
|
//
|
|
if (target is RuntimeValueExpression)
|
|
return this;
|
|
|
|
TypeSpec target_type = target.Type;
|
|
|
|
//
|
|
// 1. the return type is implicitly convertible to the type of target
|
|
//
|
|
if (Convert.ImplicitConversionExists (ec, source, target_type)) {
|
|
source = Convert.ImplicitConversion (ec, source, target_type, loc);
|
|
return this;
|
|
}
|
|
|
|
//
|
|
// Otherwise, if the selected operator is a predefined operator
|
|
//
|
|
Binary b = source as Binary;
|
|
if (b == null) {
|
|
if (source is ReducedExpression)
|
|
b = ((ReducedExpression) source).OriginalExpression as Binary;
|
|
else if (source is ReducedExpression.ReducedConstantExpression) {
|
|
b = ((ReducedExpression.ReducedConstantExpression) source).OriginalExpression as Binary;
|
|
} else if (source is Nullable.LiftedBinaryOperator) {
|
|
var po = ((Nullable.LiftedBinaryOperator) source);
|
|
if (po.UserOperator == null)
|
|
b = po.Binary;
|
|
} else if (source is TypeCast) {
|
|
b = ((TypeCast) source).Child as Binary;
|
|
}
|
|
}
|
|
|
|
if (b != null) {
|
|
//
|
|
// 2a. the operator is a shift operator
|
|
//
|
|
// 2b. the return type is explicitly convertible to the type of x, and
|
|
// y is implicitly convertible to the type of x
|
|
//
|
|
if ((b.Oper & Binary.Operator.ShiftMask) != 0 ||
|
|
Convert.ImplicitConversionExists (ec, right, target_type)) {
|
|
source = Convert.ExplicitConversion (ec, source, target_type, loc);
|
|
return this;
|
|
}
|
|
}
|
|
|
|
if (source.Type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
|
|
Arguments arg = new Arguments (1);
|
|
arg.Add (new Argument (source));
|
|
return new SimpleAssign (target, new DynamicConversion (target_type, CSharpBinderFlags.ConvertExplicit, arg, loc), loc).Resolve (ec);
|
|
}
|
|
|
|
right.Error_ValueCannotBeConverted (ec, target_type, false);
|
|
return null;
|
|
}
|
|
|
|
protected override void CloneTo (CloneContext clonectx, Expression t)
|
|
{
|
|
CompoundAssign ctarget = (CompoundAssign) t;
|
|
|
|
ctarget.right = ctarget.source = source.Clone (clonectx);
|
|
ctarget.target = target.Clone (clonectx);
|
|
}
|
|
|
|
public override object Accept (StructuralVisitor visitor)
|
|
{
|
|
return visitor.Visit (this);
|
|
}
|
|
}
|
|
}
|