mcs/class/System.Core/System.Linq.Expressions/LambdaExpression.cs

   1 //
   2 // LambdaExpression.cs
   3 //
   4 // Author:
   5 //   Jb Evain (jbevain@novell.com)
   6 //   Miguel de Icaza (miguel@novell.com)
   7 //
   8 // (C) 2008 Novell, Inc. (http://www.novell.com)
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29
  30 using System;
  31 using System.Collections.ObjectModel;
  32 using System.Collections.Generic;
  33 using System.Reflection;
  34 using System.Reflection.Emit;
  35 using System.Threading;
  36
  37 namespace System.Linq.Expressions {
  38
  39         internal class EmitContext {
  40                 internal LambdaExpression Owner;
  41                 internal Type [] ParamTypes;
  42                 internal DynamicMethod Method;
  43                 internal ILGenerator ig;
  44
  45                 static object mlock = new object ();
  46                 internal static int method_count;
  47                 static string GenName ()
  48                 {
  49                         lock (mlock){
  50                                 return "<LINQ-" + method_count++ + ">";
  51                         }
  52                 }
  53
  54                 public EmitContext (LambdaExpression owner)
  55                 {
  56                         Owner = owner;
  57
  58                         ParamTypes = new Type [Owner.parameters.Count];
  59                         for (int i = 0; i < Owner.parameters.Count; i++)
  60                                 ParamTypes [i] = Owner.parameters [i].Type;
  61
  62                         //
  63                         // We probably want to use the 3.5 new API calls to associate
  64                         // the method with the "sandboxed" Assembly, instead am currently
  65                         // dumping these types in this class
  66                         //
  67                         Type owner_of_code = typeof (EmitContext);
  68
  69
  70                         //
  71                         // FIXME: Need to force this to be verifiable, see:
  72                         // https://bugzilla.novell.com/show_bug.cgi?id=355005
  73                         //
  74                         string name = GenName ();
  75                         Method = new DynamicMethod (name, Owner.Type, ParamTypes, owner_of_code);
  76
  77                         ig = Method.GetILGenerator ();
  78                 }
  79
  80                 internal Delegate CreateDelegate ()
  81                 {
  82                         return Method.CreateDelegate (Owner.delegate_type);
  83                 }
  84
  85                 internal int GetParameterPosition (ParameterExpression p)
  86                 {
  87                         ReadOnlyCollection<ParameterExpression> pars = Owner.Parameters;
  88
  89                         for (int i = 0; i < pars.Count; i++){
  90                                 if (pars [i] == p)
  91                                         return i;
  92                         }
  93                         throw new InvalidOperationException ("Parameter not in scope");
  94                 }
  95         }
  96
  97         public class LambdaExpression : Expression {
  98
  99                 //
 100                 // LambdaExpression parameters
 101                 //
 102                 Expression body;
 103                 internal ReadOnlyCollection<ParameterExpression> parameters;
 104                 internal Type delegate_type;
 105
 106                 // This is set during compilation
 107                 Delegate lambda_delegate;
 108
 109                 static bool CanAssign (Type target, Type source)
 110                 {
 111                         // This catches object and value type mixage, type compatibility is handled later
 112                         if (target.IsValueType ^ source.IsValueType)
 113                                 return false;
 114
 115                         return target.IsAssignableFrom (source);
 116                 }
 117
 118                 internal LambdaExpression (Type delegateType, Expression body, ReadOnlyCollection<ParameterExpression> parameters)
 119                         : base (ExpressionType.Lambda, body.Type)
 120                 {
 121                         if (!delegateType.IsSubclassOf (typeof (System.Delegate))){
 122                                 throw new ArgumentException ("delegateType");
 123                         }
 124
 125                         MethodInfo [] invokes = delegateType.GetMethods (BindingFlags.Instance | BindingFlags.Public);
 126                         MethodInfo invoke = null;
 127                         foreach (MethodInfo m in invokes){
 128                                 if (m.Name == "Invoke"){
 129                                         invoke = m;
 130                                         break;
 131                                 }
 132                         }
 133                         if (invoke == null)
 134                                 throw new ArgumentException ("delegate must contain an Invoke method", "delegateType");
 135
 136                         ParameterInfo [] invoke_parameters = invoke.GetParameters ();
 137                         if (invoke_parameters.Length != parameters.Count)
 138                                 throw new ArgumentException ("Different number of arguments in delegate {0}", "delegateType");
 139
 140                         for (int i = 0; i < invoke_parameters.Length; i++){
 141                                 if (!CanAssign (parameters [i].Type, invoke_parameters [i].ParameterType))
 142                                         throw new ArgumentException (String.Format ("Can not assign a {0} to a {1}", invoke_parameters [i].ParameterType, parameters [i].Type));
 143                         }
 144
 145                         if (!CanAssign (invoke.ReturnType, body.Type))
 146                                 throw new ArgumentException (String.Format ("body type {0} can not be assigned to {1}", body.Type, invoke.ReturnType));
 147
 148                         this.body = body;
 149                         this.parameters = parameters;
 150                         delegate_type = delegateType;
 151                 }
 152
 153                 public Expression Body {
 154                         get { return body; }
 155                 }
 156
 157                 public ReadOnlyCollection<ParameterExpression> Parameters {
 158                         get { return parameters; }
 159                 }
 160
 161                 internal override void Emit (EmitContext ec)
 162                 {
 163                         throw new NotImplementedException ();
 164                 }
 165
 166                 public Delegate Compile ()
 167                 {
 168                         if (lambda_delegate == null){
 169                                 EmitContext ec = new EmitContext (this);
 170
 171                                 body.Emit (ec);
 172                                 ec.ig.Emit (OpCodes.Ret);
 173
 174                                 if (Environment.GetEnvironmentVariable ("LINQ_DBG") != null){
 175                                         string fname = "linq" + (EmitContext.method_count-1) + ".dll";
 176                                         AssemblyBuilder ab = Thread.GetDomain ().DefineDynamicAssembly (
 177                                                 new AssemblyName (fname), AssemblyBuilderAccess.RunAndSave, "/tmp");
 178
 179                                         ModuleBuilder b = ab.DefineDynamicModule (fname, fname);
 180                                         TypeBuilder tb = b.DefineType ("LINQ", TypeAttributes.Public);
 181                                         MethodBuilder mb = tb.DefineMethod ("GeneratedMethod", MethodAttributes.Static, Type, ec.ParamTypes);
 182                                         ec.ig = mb.GetILGenerator ();
 183
 184                                         body.Emit (ec);
 185                                         ec.ig.Emit (OpCodes.Ret);
 186
 187                                         tb.CreateType ();
 188                                         ab.Save (fname);
 189                                 }
 190
 191                                 lambda_delegate = ec.CreateDelegate ();
 192                         }
 193                         return lambda_delegate;
 194                 }
 195         }
 196 }