2 // assign.cs: Assignments.
5 // Miguel de Icaza (miguel@ximian.com)
6 // Martin Baulig (martin@ximian.com)
7 // Marek Safar (marek.safar@gmail.com)
9 // Dual licensed under the terms of the MIT X11 or GNU GPL
11 // Copyright 2001, 2002, 2003 Ximian, Inc.
12 // Copyright 2004-2008 Novell, Inc
17 using IKVM
.Reflection
.Emit
;
19 using System
.Reflection
.Emit
;
22 namespace Mono
.CSharp
{
25 /// This interface is implemented by expressions that can be assigned to.
28 /// This interface is implemented by Expressions whose values can not
29 /// store the result on the top of the stack.
31 /// Expressions implementing this (Properties, Indexers and Arrays) would
32 /// perform an assignment of the Expression "source" into its final
35 /// No values on the top of the stack are expected to be left by
36 /// invoking this method.
38 public interface IAssignMethod
{
40 // This is an extra version of Emit. If leave_copy is `true'
41 // A copy of the expression will be left on the stack at the
42 // end of the code generated for EmitAssign
44 void Emit (EmitContext ec
, bool leave_copy
);
47 // This method does the assignment
48 // `source' will be stored into the location specified by `this'
49 // if `leave_copy' is true, a copy of `source' will be left on the stack
50 // if `prepare_for_load' is true, when `source' is emitted, there will
51 // be data on the stack that it can use to compuatate its value. This is
52 // for expressions like a [f ()] ++, where you can't call `f ()' twice.
54 void EmitAssign (EmitContext ec
, Expression source
, bool leave_copy
, bool isCompound
);
57 For simple assignments, this interface is very simple, EmitAssign is called with source
58 as the source expression and leave_copy and prepare_for_load false.
60 For compound assignments it gets complicated.
62 EmitAssign will be called as before, however, prepare_for_load will be
63 true. The @source expression will contain an expression
64 which calls Emit. So, the calls look like:
66 this.EmitAssign (ec, source, false, true) ->
69 this.Emit (ec, false); ->
70 end this.Emit (ec, false); ->
73 end this.EmitAssign (ec, source, false, true)
76 When prepare_for_load is true, EmitAssign emits a `token' on the stack that
77 Emit will use for its state.
79 Let's take FieldExpr as an example. assume we are emitting f ().y += 1;
81 Here is the call tree again. This time, each call is annotated with the IL
84 this.EmitAssign (ec, source, false, true)
89 this.Emit (ec, false);
91 end this.Emit (ec, false);
101 end this.EmitAssign (ec, source, false, true)
104 1) EmitAssign left a token on the stack. It was the result of f ().
105 2) This token was used by Emit
107 leave_copy (in both EmitAssign and Emit) tells the compiler to leave a copy
108 of the expression at that point in evaluation. This is used for pre/post inc/dec
109 and for a = x += y. Let's do the above example with leave_copy true in EmitAssign
111 this.EmitAssign (ec, source, true, true)
116 this.Emit (ec, false);
118 end this.Emit (ec, false);
131 end this.EmitAssign (ec, source, true, true)
133 And with it true in Emit
135 this.EmitAssign (ec, source, false, true)
140 this.Emit (ec, true);
144 end this.Emit (ec, true);
155 end this.EmitAssign (ec, source, false, true)
157 Note that these two examples are what happens for ++x and x++, respectively.
162 /// An Expression to hold a temporary value.
165 /// The LocalTemporary class is used to hold temporary values of a given
166 /// type to "simulate" the expression semantics. The local variable is
169 /// The local temporary is used to alter the normal flow of code generation
170 /// basically it creates a local variable, and its emit instruction generates
171 /// code to access this value, return its address or save its value.
173 /// If `is_address' is true, then the value that we store is the address to the
174 /// real value, and not the value itself.
176 /// This is needed for a value type, because otherwise you just end up making a
177 /// copy of the value on the stack and modifying it. You really need a pointer
178 /// to the origional value so that you can modify it in that location. This
179 /// Does not happen with a class because a class is a pointer -- so you always
180 /// get the indirection.
183 public class LocalTemporary
: Expression
, IMemoryLocation
, IAssignMethod
{
184 LocalBuilder builder
;
186 public LocalTemporary (TypeSpec t
)
189 eclass
= ExprClass
.Value
;
192 public LocalTemporary (LocalBuilder b
, TypeSpec t
)
198 public void Release (EmitContext ec
)
200 ec
.FreeTemporaryLocal (builder
, type
);
204 public override bool ContainsEmitWithAwait ()
209 public override Expression
CreateExpressionTree (ResolveContext ec
)
211 Arguments args
= new Arguments (1);
212 args
.Add (new Argument (this));
213 return CreateExpressionFactoryCall (ec
, "Constant", args
);
216 protected override Expression
DoResolve (ResolveContext ec
)
221 public override Expression
DoResolveLValue (ResolveContext ec
, Expression right_side
)
226 public override void Emit (EmitContext ec
)
229 throw new InternalErrorException ("Emit without Store, or after Release");
231 ec
.Emit (OpCodes
.Ldloc
, builder
);
234 #region IAssignMethod Members
236 public void Emit (EmitContext ec
, bool leave_copy
)
244 public void EmitAssign (EmitContext ec
, Expression source
, bool leave_copy
, bool isCompound
)
247 throw new NotImplementedException ();
259 public LocalBuilder Builder
{
260 get { return builder; }
263 public void Store (EmitContext ec
)
266 builder
= ec
.GetTemporaryLocal (type
);
268 ec
.Emit (OpCodes
.Stloc
, builder
);
271 public void AddressOf (EmitContext ec
, AddressOp mode
)
274 builder
= ec
.GetTemporaryLocal (type
);
276 if (builder
.LocalType
.IsByRef
) {
278 // if is_address, than this is just the address anyways,
279 // so we just return this.
281 ec
.Emit (OpCodes
.Ldloc
, builder
);
283 ec
.Emit (OpCodes
.Ldloca
, builder
);
289 /// The Assign node takes care of assigning the value of source into
290 /// the expression represented by target.
292 public abstract class Assign
: ExpressionStatement
{
293 protected Expression target
, source
;
295 protected Assign (Expression target
, Expression source
, Location loc
)
297 this.target
= target
;
298 this.source
= source
;
302 public Expression Target
{
303 get { return target; }
306 public Expression Source
{
312 public override bool ContainsEmitWithAwait ()
314 return target
.ContainsEmitWithAwait () || source
.ContainsEmitWithAwait ();
317 public override Expression
CreateExpressionTree (ResolveContext ec
)
319 ec
.Report
.Error (832, loc
, "An expression tree cannot contain an assignment operator");
323 protected override Expression
DoResolve (ResolveContext ec
)
326 source
= source
.Resolve (ec
);
328 if (source
== null) {
330 source
= EmptyExpression
.Null
;
333 target
= target
.ResolveLValue (ec
, source
);
335 if (target
== null || !ok
)
338 TypeSpec target_type
= target
.Type
;
339 TypeSpec source_type
= source
.Type
;
341 eclass
= ExprClass
.Value
;
344 if (!(target
is IAssignMethod
)) {
345 Error_ValueAssignment (ec
, loc
);
349 if (target_type
!= source_type
) {
350 Expression resolved
= ResolveConversions (ec
);
352 if (resolved
!= this)
360 public override System
.Linq
.Expressions
.Expression
MakeExpression (BuilderContext ctx
)
362 var tassign
= target
as IDynamicAssign
;
364 throw new InternalErrorException (target
.GetType () + " does not support dynamic assignment");
366 var target_object
= tassign
.MakeAssignExpression (ctx
, source
);
369 // Some hacking is needed as DLR does not support void type and requires
370 // always have object convertible return type to support caching and chaining
372 // We do this by introducing an explicit block which returns RHS value when
375 if (target_object
.NodeType
== System
.Linq
.Expressions
.ExpressionType
.Block
)
376 return target_object
;
378 System
.Linq
.Expressions
.UnaryExpression source_object
;
379 if (ctx
.HasSet (BuilderContext
.Options
.CheckedScope
)) {
380 source_object
= System
.Linq
.Expressions
.Expression
.ConvertChecked (source
.MakeExpression (ctx
), target_object
.Type
);
382 source_object
= System
.Linq
.Expressions
.Expression
.Convert (source
.MakeExpression (ctx
), target_object
.Type
);
385 return System
.Linq
.Expressions
.Expression
.Assign (target_object
, source_object
);
388 protected virtual Expression
ResolveConversions (ResolveContext ec
)
390 source
= Convert
.ImplicitConversionRequired (ec
, source
, target
.Type
, source
.Location
);
397 void Emit (EmitContext ec
, bool is_statement
)
399 IAssignMethod t
= (IAssignMethod
) target
;
400 t
.EmitAssign (ec
, source
, !is_statement
, this is CompoundAssign
);
403 public override void Emit (EmitContext ec
)
408 public override void EmitStatement (EmitContext ec
)
413 protected override void CloneTo (CloneContext clonectx
, Expression t
)
415 Assign _target
= (Assign
) t
;
417 _target
.target
= target
.Clone (clonectx
);
418 _target
.source
= source
.Clone (clonectx
);
422 public class SimpleAssign
: Assign
424 public SimpleAssign (Expression target
, Expression source
)
425 : this (target
, source
, target
.Location
)
429 public SimpleAssign (Expression target
, Expression source
, Location loc
)
430 : base (target
, source
, loc
)
434 bool CheckEqualAssign (Expression t
)
436 if (source
is Assign
) {
437 Assign a
= (Assign
) source
;
438 if (t
.Equals (a
.Target
))
440 return a
is SimpleAssign
&& ((SimpleAssign
) a
).CheckEqualAssign (t
);
442 return t
.Equals (source
);
445 protected override Expression
DoResolve (ResolveContext ec
)
447 Expression e
= base.DoResolve (ec
);
448 if (e
== null || e
!= this)
451 if (CheckEqualAssign (target
))
452 ec
.Report
.Warning (1717, 3, loc
, "Assignment made to same variable; did you mean to assign something else?");
458 public class RuntimeExplicitAssign
: Assign
460 public RuntimeExplicitAssign (Expression target
, Expression source
)
461 : base (target
, source
, target
.Location
)
465 protected override Expression
ResolveConversions (ResolveContext ec
)
467 source
= EmptyCast
.Create (source
, target
.Type
);
473 // Compiler generated assign
475 class CompilerAssign
: Assign
477 public CompilerAssign (Expression target
, Expression source
, Location loc
)
478 : base (target
, source
, loc
)
482 public void UpdateSource (Expression source
)
484 base.source
= source
;
489 // Implements fields and events class initializers
491 public class FieldInitializer
: Assign
494 // Field initializers are tricky for partial classes. They have to
495 // share same constructor (block) for expression trees resolve but
496 // they have they own resolve scope
498 sealed class FieldInitializerContext
: ResolveContext
500 ExplicitBlock ctor_block
;
502 public FieldInitializerContext (IMemberContext mc
, ResolveContext constructorContext
)
503 : base (mc
, Options
.FieldInitializerScope
| Options
.ConstructorScope
)
505 this.ctor_block
= constructorContext
.CurrentBlock
.Explicit
;
508 public override ExplicitBlock ConstructorBlock
{
516 // Keep resolved value because field initializers have their own rules
518 ExpressionStatement resolved
;
521 public FieldInitializer (FieldSpec spec
, Expression expression
, IMemberContext mc
)
522 : base (new FieldExpr (spec
, expression
.Location
), expression
, expression
.Location
)
526 ((FieldExpr
)target
).InstanceExpression
= new CompilerGeneratedThis (mc
.CurrentType
, expression
.Location
);
529 protected override Expression
DoResolve (ResolveContext ec
)
531 // Field initializer can be resolved (fail) many times
535 if (resolved
== null) {
536 var ctx
= new FieldInitializerContext (mc
, ec
);
537 resolved
= base.DoResolve (ctx
) as ExpressionStatement
;
543 public override void EmitStatement (EmitContext ec
)
545 if (resolved
== null)
548 if (resolved
!= this)
549 resolved
.EmitStatement (ec
);
551 base.EmitStatement (ec
);
554 public bool IsDefaultInitializer
{
556 Constant c
= source
as Constant
;
560 FieldExpr fe
= (FieldExpr
)target
;
561 return c
.IsDefaultInitializer (fe
.Type
);
565 public override bool IsSideEffectFree
{
567 return source
.IsSideEffectFree
;
573 // This class is used for compound assignments.
575 public class CompoundAssign
: Assign
577 // This is just a hack implemented for arrays only
578 public sealed class TargetExpression
: Expression
580 readonly Expression child
;
582 public TargetExpression (Expression child
)
585 this.loc
= child
.Location
;
588 public override bool ContainsEmitWithAwait ()
590 return child
.ContainsEmitWithAwait ();
593 public override Expression
CreateExpressionTree (ResolveContext ec
)
595 throw new NotSupportedException ("ET");
598 protected override Expression
DoResolve (ResolveContext ec
)
601 eclass
= ExprClass
.Value
;
605 public override void Emit (EmitContext ec
)
610 public override Expression
EmitToField (EmitContext ec
)
612 return child
.EmitToField (ec
);
616 // Used for underlying binary operator
617 readonly Binary
.Operator op
;
621 public CompoundAssign (Binary
.Operator op
, Expression target
, Expression source
, Location loc
)
622 : base (target
, source
, loc
)
628 public CompoundAssign (Binary
.Operator op
, Expression target
, Expression source
, Expression left
, Location loc
)
629 : this (op
, target
, source
, loc
)
634 protected override Expression
DoResolve (ResolveContext ec
)
636 right
= right
.Resolve (ec
);
640 MemberAccess ma
= target
as MemberAccess
;
641 using (ec
.Set (ResolveContext
.Options
.CompoundAssignmentScope
)) {
642 target
= target
.Resolve (ec
);
648 if (target
is MethodGroupExpr
){
649 ec
.Report
.Error (1656, loc
,
650 "Cannot assign to `{0}' because it is a `{1}'",
651 ((MethodGroupExpr
)target
).Name
, target
.ExprClassName
);
655 var event_expr
= target
as EventExpr
;
656 if (event_expr
!= null) {
657 source
= Convert
.ImplicitConversionRequired (ec
, right
, target
.Type
, loc
);
662 if (op
== Binary
.Operator
.Addition
)
663 rside
= EmptyExpression
.EventAddition
;
664 else if (op
== Binary
.Operator
.Subtraction
)
665 rside
= EmptyExpression
.EventSubtraction
;
669 target
= target
.ResolveLValue (ec
, rside
);
673 eclass
= ExprClass
.Value
;
674 type
= event_expr
.Operator
.ReturnType
;
679 // Only now we can decouple the original source/target
680 // into a tree, to guarantee that we do not have side
684 left
= new TargetExpression (target
);
686 source
= new Binary (op
, left
, right
, true, loc
);
688 if (target
is DynamicMemberAssignable
) {
689 Arguments targs
= ((DynamicMemberAssignable
) target
).Arguments
;
690 source
= source
.Resolve (ec
);
692 Arguments args
= new Arguments (targs
.Count
+ 1);
693 args
.AddRange (targs
);
694 args
.Add (new Argument (source
));
696 var binder_flags
= CSharpBinderFlags
.ValueFromCompoundAssignment
;
699 // Compound assignment does target conversion using additional method
700 // call, set checked context as the binary operation can overflow
702 if (ec
.HasSet (ResolveContext
.Options
.CheckedScope
))
703 binder_flags
|= CSharpBinderFlags
.CheckedContext
;
705 if (target
is DynamicMemberBinder
) {
706 source
= new DynamicMemberBinder (ma
.Name
, binder_flags
, args
, loc
).Resolve (ec
);
708 // Handles possible event addition/subtraction
709 if (op
== Binary
.Operator
.Addition
|| op
== Binary
.Operator
.Subtraction
) {
710 args
= new Arguments (targs
.Count
+ 1);
711 args
.AddRange (targs
);
712 args
.Add (new Argument (right
));
713 string method_prefix
= op
== Binary
.Operator
.Addition
?
714 Event
.AEventAccessor
.AddPrefix
: Event
.AEventAccessor
.RemovePrefix
;
716 var invoke
= DynamicInvocation
.CreateSpecialNameInvoke (
717 new MemberAccess (right
, method_prefix
+ ma
.Name
, loc
), args
, loc
).Resolve (ec
);
719 args
= new Arguments (targs
.Count
);
720 args
.AddRange (targs
);
721 source
= new DynamicEventCompoundAssign (ma
.Name
, args
,
722 (ExpressionStatement
) source
, (ExpressionStatement
) invoke
, loc
).Resolve (ec
);
725 source
= new DynamicIndexBinder (binder_flags
, args
, loc
).Resolve (ec
);
731 return base.DoResolve (ec
);
734 protected override Expression
ResolveConversions (ResolveContext ec
)
737 // LAMESPEC: Under dynamic context no target conversion is happening
738 // This allows more natual dynamic behaviour but breaks compatibility
739 // with static binding
741 if (target
is RuntimeValueExpression
)
744 TypeSpec target_type
= target
.Type
;
747 // 1. the return type is implicitly convertible to the type of target
749 if (Convert
.ImplicitConversionExists (ec
, source
, target_type
)) {
750 source
= Convert
.ImplicitConversion (ec
, source
, target_type
, loc
);
755 // Otherwise, if the selected operator is a predefined operator
757 Binary b
= source
as Binary
;
758 if (b
== null && source
is ReducedExpression
)
759 b
= ((ReducedExpression
) source
).OriginalExpression
as Binary
;
763 // 2a. the operator is a shift operator
765 // 2b. the return type is explicitly convertible to the type of x, and
766 // y is implicitly convertible to the type of x
768 if ((b
.Oper
& Binary
.Operator
.ShiftMask
) != 0 ||
769 Convert
.ImplicitConversionExists (ec
, right
, target_type
)) {
770 source
= Convert
.ExplicitConversion (ec
, source
, target_type
, loc
);
775 if (source
.Type
.BuiltinType
== BuiltinTypeSpec
.Type
.Dynamic
) {
776 Arguments arg
= new Arguments (1);
777 arg
.Add (new Argument (source
));
778 return new SimpleAssign (target
, new DynamicConversion (target_type
, CSharpBinderFlags
.ConvertExplicit
, arg
, loc
), loc
).Resolve (ec
);
781 right
.Error_ValueCannotBeConverted (ec
, loc
, target_type
, false);
785 protected override void CloneTo (CloneContext clonectx
, Expression t
)
787 CompoundAssign ctarget
= (CompoundAssign
) t
;
789 ctarget
.right
= ctarget
.source
= source
.Clone (clonectx
);
790 ctarget
.target
= target
.Clone (clonectx
);