2 // lambda.cs: support for lambda expressions
4 // Authors: Miguel de Icaza (miguel@gnu.org)
6 // Licensed under the terms of the GNU GPL
8 // (C) 2007 Novell, Inc
12 using System.Collections;
13 using System.Reflection;
14 using System.Reflection.Emit;
16 namespace Mono.CSharp {
17 public class LambdaExpression : AnonymousMethodExpression {
18 bool explicit_parameters;
21 // The parameter list can either be:
22 // null: no parameters
23 // arraylist of Parameter (explicitly typed parameters)
24 // arraylist of strings (implicitly typed parameters)
26 public LambdaExpression (AnonymousMethodExpression parent,
27 GenericMethod generic, TypeContainer host,
28 Parameters parameters, Block container,
30 : base (parent, generic, host, parameters, container, loc)
32 explicit_parameters = (parameters != null && parameters.Count > 0 && parameters [0].TypeName != null);
33 if (parameters == null)
34 Parameters = new Parameters (new Parameter [0]);
37 public override Expression DoResolve (EmitContext ec)
39 eclass = ExprClass.Value;
40 type = TypeManager.anonymous_method_type;
42 if (explicit_parameters){
43 if (!Parameters.Resolve (ec))
47 // We will resolve parameters later, we do not
48 // have information at this point.
53 public override void Emit (EmitContext ec)
58 public override bool ImplicitStandardConversionExists (Type delegate_type)
60 EmitContext ec = EmitContext.TempEc;
65 Report.DisableErrors ();
66 result = DoCompatibleTest (ec, delegate_type, true) != null;
68 Console.WriteLine ("INFO: Lambda.Compatible Passed for {0}", delegate_type);
70 Console.WriteLine ("INFO: Lambda.Compatible Failed for {0}", delegate_type);
72 Report.EnableErrors ();
82 // Returns true if this anonymous method can be implicitly
83 // converted to the delegate type `delegate_type'
85 public override Expression Compatible (EmitContext ec, Type delegate_type)
87 return DoCompatibleTest (ec, delegate_type, false);
90 Expression DoCompatibleTest (EmitContext ec, Type delegate_type, bool clone)
92 if (anonymous != null)
93 return anonymous.AnonymousDelegate;
95 if (CompatibleChecks (ec, delegate_type) == null)
98 MethodGroupExpr invoke_mg = Delegate.GetInvokeMethod (
99 ec.ContainerType, delegate_type, loc);
100 MethodInfo invoke_mb = (MethodInfo) invoke_mg.Methods [0];
101 ParameterData invoke_pd = TypeManager.GetParameterData (invoke_mb);
104 // The lambda expression is compatible with the delegate type,
109 // D and L have the same number of arguments.
110 if (Parameters.Count != invoke_pd.Count)
113 if (explicit_parameters){
115 // If L has an explicitly typed parameter list, each parameter
116 // in D has the same type and modifiers as the corresponding
119 if (!VerifyExplicitParameterCompatibility (delegate_type, invoke_pd))
123 // If L has an implicitly typed parameter list, D has no ref or
126 // Note: We currently do nothing, because the preview does not
127 // follow the above rule.
130 // each parameter of L is given the type of the corresponding parameter in D
133 for (int i = 0; i < invoke_pd.Count; i++)
134 Parameters [i].TypeName = new TypeExpression (
135 invoke_pd.ParameterType (i),
136 Parameters [i].Location);
140 // The return type of the delegate must be compatible with
141 // the anonymous type. Instead of doing a pass to examine the block
142 // we satisfy the rule by setting the return type on the EmitContext
143 // to be the delegate type return type.
146 ToplevelBlock b = clone ? (ToplevelBlock) Block.PerformClone () : Block;
148 anonymous = new AnonymousMethod (
149 Parent != null ? Parent.AnonymousMethod : null, RootScope, Host,
150 GenericMethod, Parameters, Container, b, invoke_mb.ReturnType,
153 if (!anonymous.Resolve (ec))
156 return anonymous.AnonymousDelegate;
161 // This is a return statement that is prepended lambda expression bodies that happen
162 // to be expressions. Depending on the return type of the delegate this will behave
163 // as either { expr (); return (); } or { return expr (); }
165 public class ContextualReturn : Statement {
166 public Expression Expr;
168 public ContextualReturn (Expression e)
176 public override bool Resolve (EmitContext ec)
178 AnonymousContainer am = ec.CurrentAnonymousMethod;
179 if ((am != null) && am.IsIterator && ec.InIterator) {
180 Report.Error (1622, loc, "Cannot return a value from iterators. Use the yield return " +
181 "statement to return a value, or yield break to end the iteration");
185 Expr = Expr.Resolve (ec);
189 if (ec.ReturnType == null){
190 if (!(Expr is ExpressionStatement)){
191 Expression.Error_InvalidExpressionStatement (Expr.Location);
195 if (Expr.Type != ec.ReturnType) {
196 Expr = Convert.ImplicitConversionRequired (
197 ec, Expr, ec.ReturnType, loc);
203 int errors = Report.Errors;
204 unwind_protect = ec.CurrentBranching.AddReturnOrigin (ec.CurrentBranching.CurrentUsageVector, loc);
206 ec.NeedReturnLabel ();
207 ec.CurrentBranching.CurrentUsageVector.Return ();
208 return errors == Report.Errors;
211 protected override void DoEmit (EmitContext ec)
216 ec.ig.Emit (OpCodes.Stloc, ec.TemporaryReturn ());
217 ec.ig.Emit (OpCodes.Leave, ec.ReturnLabel);
219 ec.ig.Emit (OpCodes.Ret);
222 protected override void CloneTo (CloneContext clonectx, Statement t)
224 ContextualReturn cr = (ContextualReturn) t;
226 cr.Expr = Expr.Clone (clonectx);