mcs/mcs/lambda.cs

   1 //
   2 // lambda.cs: support for lambda expressions
   3 //
   4 // Authors: Miguel de Icaza (miguel@gnu.org)
   5 //          Marek Safar (marek.safar@gmail.com)
   6 //
   7 // Dual licensed under the terms of the MIT X11 or GNU GPL
   8 //
   9 // Copyright 2007-2008 Novell, Inc
  10 //
  11
  12 #if STATIC
  13 using IKVM.Reflection.Emit;
  14 #else
  15 using System.Reflection.Emit;
  16 #endif
  17
  18 namespace Mono.CSharp {
  19         public class LambdaExpression : AnonymousMethodExpression
  20         {
  21                 //
  22                 // The parameters can either be:
  23                 //    A list of Parameters (explicitly typed parameters)
  24                 //    An ImplicitLambdaParameter
  25                 //
  26                 public LambdaExpression (Location loc)
  27                         : base (loc)
  28                 {
  29                 }
  30
  31                 protected override Expression CreateExpressionTree (ResolveContext ec, TypeSpec delegate_type)
  32                 {
  33                         if (ec.IsInProbingMode)
  34                                 return this;
  35
  36                         BlockContext bc = new BlockContext (ec.MemberContext, ec.ConstructorBlock, ec.BuiltinTypes.Void) {
  37                                 CurrentAnonymousMethod = ec.CurrentAnonymousMethod
  38                         };
  39
  40                         Expression args = Parameters.CreateExpressionTree (bc, loc);
  41                         Expression expr = Block.CreateExpressionTree (ec);
  42                         if (expr == null)
  43                                 return null;
  44
  45                         Arguments arguments = new Arguments (2);
  46                         arguments.Add (new Argument (expr));
  47                         arguments.Add (new Argument (args));
  48                         return CreateExpressionFactoryCall (ec, "Lambda",
  49                                 new TypeArguments (new TypeExpression (delegate_type, loc)),
  50                                 arguments);
  51                 }
  52
  53                 public override bool HasExplicitParameters {
  54                         get {
  55                                 return Parameters.Count > 0 && !(Parameters.FixedParameters [0] is ImplicitLambdaParameter);
  56                         }
  57                 }
  58
  59                 protected override ParametersCompiled ResolveParameters (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegateType)
  60                 {
  61                         if (!delegateType.IsDelegate)
  62                                 return null;
  63
  64                         AParametersCollection d_params = Delegate.GetParameters (delegateType);
  65
  66                         if (HasExplicitParameters) {
  67                                 if (!VerifyExplicitParameters (ec, delegateType, d_params))
  68                                         return null;
  69
  70                                 return Parameters;
  71                         }
  72
  73                         //
  74                         // If L has an implicitly typed parameter list we make implicit parameters explicit
  75                         // Set each parameter of L is given the type of the corresponding parameter in D
  76                         //
  77                         if (!VerifyParameterCompatibility (ec, delegateType, d_params, ec.IsInProbingMode))
  78                                 return null;
  79
  80                         TypeSpec [] ptypes = new TypeSpec [Parameters.Count];
  81                         for (int i = 0; i < d_params.Count; i++) {
  82                                 // D has no ref or out parameters
  83                                 if ((d_params.FixedParameters [i].ModFlags & Parameter.Modifier.ISBYREF) != 0)
  84                                         return null;
  85
  86                                 TypeSpec d_param = d_params.Types [i];
  87
  88                                 //
  89                                 // When type inference context exists try to apply inferred type arguments
  90                                 //
  91                                 if (tic != null) {
  92                                         d_param = tic.InflateGenericArgument (ec, d_param);
  93                                 }
  94
  95                                 ptypes [i] = d_param;
  96                                 ImplicitLambdaParameter ilp = (ImplicitLambdaParameter) Parameters.FixedParameters [i];
  97                                 ilp.SetParameterType (d_param);
  98                                 ilp.Resolve (null, i);
  99                         }
 100
 101                         Parameters.Types = ptypes;
 102                         return Parameters;
 103                 }
 104
 105                 protected override AnonymousMethodBody CompatibleMethodFactory (TypeSpec returnType, TypeSpec delegateType, ParametersCompiled p, ParametersBlock b)
 106                 {
 107                         return new LambdaMethod (p, b, returnType, delegateType, loc);
 108                 }
 109
 110                 protected override bool DoResolveParameters (ResolveContext rc)
 111                 {
 112                         //
 113                         // Only explicit parameters can be resolved at this point
 114                         //
 115                         if (HasExplicitParameters) {
 116                                 return Parameters.Resolve (rc);
 117                         }
 118
 119                         return true;
 120                 }
 121
 122                 public override string GetSignatureForError ()
 123                 {
 124                         return "lambda expression";
 125                 }
 126         }
 127
 128         class LambdaMethod : AnonymousMethodBody
 129         {
 130                 public LambdaMethod (ParametersCompiled parameters,
 131                                         ParametersBlock block, TypeSpec return_type, TypeSpec delegate_type,
 132                                         Location loc)
 133                         : base (parameters, block, return_type, delegate_type, loc)
 134                 {
 135                 }
 136
 137                 #region Properties
 138
 139                 public override string ContainerType {
 140                         get {
 141                                 return "lambda expression";
 142                         }
 143                 }
 144
 145                 #endregion
 146
 147                 protected override void CloneTo (CloneContext clonectx, Expression target)
 148                 {
 149                         // TODO: nothing ??
 150                 }
 151
 152                 public override Expression CreateExpressionTree (ResolveContext ec)
 153                 {
 154                         BlockContext bc = new BlockContext (ec.MemberContext, Block, ReturnType);
 155                         Expression args = parameters.CreateExpressionTree (bc, loc);
 156                         Expression expr = Block.CreateExpressionTree (ec);
 157                         if (expr == null)
 158                                 return null;
 159
 160                         Arguments arguments = new Arguments (2);
 161                         arguments.Add (new Argument (expr));
 162                         arguments.Add (new Argument (args));
 163                         return CreateExpressionFactoryCall (ec, "Lambda",
 164                                 new TypeArguments (new TypeExpression (type, loc)),
 165                                 arguments);
 166                 }
 167         }
 168
 169         //
 170         // This is a return statement that is prepended lambda expression bodies that happen
 171         // to be expressions.  Depending on the return type of the delegate this will behave
 172         // as either { expr (); return (); } or { return expr (); }
 173         //
 174         public class ContextualReturn : Return
 175         {
 176                 ExpressionStatement statement;
 177
 178                 public ContextualReturn (Expression expr)
 179                         : base (expr, expr.Location)
 180                 {
 181                 }
 182
 183                 public override Expression CreateExpressionTree (ResolveContext ec)
 184                 {
 185                         return Expr.CreateExpressionTree (ec);
 186                 }
 187
 188                 public override void Emit (EmitContext ec)
 189                 {
 190                         if (statement != null) {
 191                                 statement.EmitStatement (ec);
 192                                 ec.Emit (OpCodes.Ret);
 193                                 return;
 194                         }
 195
 196                         base.Emit (ec);
 197                 }
 198
 199                 protected override bool DoResolve (BlockContext ec)
 200                 {
 201                         //
 202                         // When delegate returns void, only expression statements can be used
 203                         //
 204                         if (ec.ReturnType.Kind == MemberKind.Void) {
 205                                 Expr = Expr.Resolve (ec);
 206                                 if (Expr == null)
 207                                         return false;
 208
 209                                 statement = Expr as ExpressionStatement;
 210                                 if (statement == null)
 211                                         Expr.Error_InvalidExpressionStatement (ec);
 212
 213                                 return true;
 214                         }
 215
 216                         return base.DoResolve (ec);
 217                 }
 218         }
 219 }