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 (bool isAsync, Location loc)
  27                         : base (isAsync, loc)
  28                 {
  29                 }
  30
  31                 public LambdaExpression (Location loc)
  32                         : this (false, loc)
  33                 {
  34                 }
  35
  36                 protected override Expression CreateExpressionTree (ResolveContext ec, TypeSpec delegate_type)
  37                 {
  38                         if (ec.IsInProbingMode)
  39                                 return this;
  40
  41                         BlockContext bc = new BlockContext (ec.MemberContext, ec.ConstructorBlock, ec.BuiltinTypes.Void) {
  42                                 CurrentAnonymousMethod = ec.CurrentAnonymousMethod
  43                         };
  44
  45                         Expression args = Parameters.CreateExpressionTree (bc, loc);
  46                         Expression expr = Block.CreateExpressionTree (ec);
  47                         if (expr == null)
  48                                 return null;
  49
  50                         Arguments arguments = new Arguments (2);
  51                         arguments.Add (new Argument (expr));
  52                         arguments.Add (new Argument (args));
  53                         return CreateExpressionFactoryCall (ec, "Lambda",
  54                                 new TypeArguments (new TypeExpression (delegate_type, loc)),
  55                                 arguments);
  56                 }
  57
  58                 public override bool HasExplicitParameters {
  59                         get {
  60                                 return Parameters.Count > 0 && !(Parameters.FixedParameters [0] is ImplicitLambdaParameter);
  61                         }
  62                 }
  63
  64                 protected override ParametersCompiled ResolveParameters (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegateType)
  65                 {
  66                         if (!delegateType.IsDelegate)
  67                                 return null;
  68
  69                         AParametersCollection d_params = Delegate.GetParameters (delegateType);
  70
  71                         if (HasExplicitParameters) {
  72                                 if (!VerifyExplicitParameters (ec, delegateType, d_params))
  73                                         return null;
  74
  75                                 return Parameters;
  76                         }
  77
  78                         //
  79                         // If L has an implicitly typed parameter list we make implicit parameters explicit
  80                         // Set each parameter of L is given the type of the corresponding parameter in D
  81                         //
  82                         if (!VerifyParameterCompatibility (ec, delegateType, d_params, ec.IsInProbingMode))
  83                                 return null;
  84
  85                         TypeSpec [] ptypes = new TypeSpec [Parameters.Count];
  86                         for (int i = 0; i < d_params.Count; i++) {
  87                                 // D has no ref or out parameters
  88                                 if ((d_params.FixedParameters [i].ModFlags & Parameter.Modifier.ISBYREF) != 0)
  89                                         return null;
  90
  91                                 TypeSpec d_param = d_params.Types [i];
  92
  93                                 //
  94                                 // When type inference context exists try to apply inferred type arguments
  95                                 //
  96                                 if (tic != null) {
  97                                         d_param = tic.InflateGenericArgument (ec, d_param);
  98                                 }
  99
 100                                 ptypes [i] = d_param;
 101                                 ImplicitLambdaParameter ilp = (ImplicitLambdaParameter) Parameters.FixedParameters [i];
 102                                 ilp.SetParameterType (d_param);
 103                                 ilp.Resolve (null, i);
 104                         }
 105
 106                         Parameters.Types = ptypes;
 107                         return Parameters;
 108                 }
 109
 110                 protected override AnonymousMethodBody CompatibleMethodFactory (TypeSpec returnType, TypeSpec delegateType, ParametersCompiled p, ParametersBlock b)
 111                 {
 112                         return new LambdaMethod (p, b, returnType, delegateType, loc);
 113                 }
 114
 115                 protected override bool DoResolveParameters (ResolveContext rc)
 116                 {
 117                         //
 118                         // Only explicit parameters can be resolved at this point
 119                         //
 120                         if (HasExplicitParameters) {
 121                                 return Parameters.Resolve (rc);
 122                         }
 123
 124                         return true;
 125                 }
 126
 127                 public override string GetSignatureForError ()
 128                 {
 129                         return "lambda expression";
 130                 }
 131         }
 132
 133         class LambdaMethod : AnonymousMethodBody
 134         {
 135                 public LambdaMethod (ParametersCompiled parameters,
 136                                         ParametersBlock block, TypeSpec return_type, TypeSpec delegate_type,
 137                                         Location loc)
 138                         : base (parameters, block, return_type, delegate_type, loc)
 139                 {
 140                 }
 141
 142                 #region Properties
 143
 144                 public override string ContainerType {
 145                         get {
 146                                 return "lambda expression";
 147                         }
 148                 }
 149
 150                 #endregion
 151
 152                 protected override void CloneTo (CloneContext clonectx, Expression target)
 153                 {
 154                         // TODO: nothing ??
 155                 }
 156
 157                 public override Expression CreateExpressionTree (ResolveContext ec)
 158                 {
 159                         BlockContext bc = new BlockContext (ec.MemberContext, Block, ReturnType);
 160                         Expression args = parameters.CreateExpressionTree (bc, loc);
 161                         Expression expr = Block.CreateExpressionTree (ec);
 162                         if (expr == null)
 163                                 return null;
 164
 165                         Arguments arguments = new Arguments (2);
 166                         arguments.Add (new Argument (expr));
 167                         arguments.Add (new Argument (args));
 168                         return CreateExpressionFactoryCall (ec, "Lambda",
 169                                 new TypeArguments (new TypeExpression (type, loc)),
 170                                 arguments);
 171                 }
 172         }
 173
 174         //
 175         // This is a return statement that is prepended lambda expression bodies that happen
 176         // to be expressions.  Depending on the return type of the delegate this will behave
 177         // as either { expr (); return (); } or { return expr (); }
 178         //
 179         public class ContextualReturn : Return
 180         {
 181                 ExpressionStatement statement;
 182
 183                 public ContextualReturn (Expression expr)
 184                         : base (expr, expr.Location)
 185                 {
 186                 }
 187
 188                 public override Expression CreateExpressionTree (ResolveContext ec)
 189                 {
 190                         return Expr.CreateExpressionTree (ec);
 191                 }
 192
 193                 public override void Emit (EmitContext ec)
 194                 {
 195                         if (statement != null) {
 196                                 statement.EmitStatement (ec);
 197                                 if (unwind_protect)
 198                                         ec.Emit (OpCodes.Leave, ec.CreateReturnLabel ());
 199                                 else {
 200                                         ec.Emit (OpCodes.Ret);
 201                                 }
 202                                 return;
 203                         }
 204
 205                         base.Emit (ec);
 206                 }
 207
 208                 protected override bool DoResolve (BlockContext ec)
 209                 {
 210                         //
 211                         // When delegate returns void, only expression statements can be used
 212                         //
 213                         if (ec.ReturnType.Kind == MemberKind.Void) {
 214                                 Expr = Expr.Resolve (ec);
 215                                 if (Expr == null)
 216                                         return false;
 217
 218                                 statement = Expr as ExpressionStatement;
 219                                 if (statement == null)
 220                                         Expr.Error_InvalidExpressionStatement (ec);
 221
 222                                 return true;
 223                         }
 224
 225                         return base.DoResolve (ec);
 226                 }
 227         }
 228 }