class/corlib/System.Reflection/EventInfo.cs

   1 //
   2 // System.Reflection/EventInfo.cs
   3 //
   4 // Author:
   5 //   Paolo Molaro (lupus@ximian.com)
   6 //
   7 // (C) 2001 Ximian, Inc.  http://www.ximian.com
   8 // Copyright (C) 2004-2005 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.Diagnostics;
  31 using System.Runtime.InteropServices;
  32
  33 namespace System.Reflection {
  34
  35         [ComVisible (true)]
  36         [ComDefaultInterfaceAttribute (typeof (_EventInfo))]
  37         [Serializable]
  38         [ClassInterface(ClassInterfaceType.None)]
  39         public abstract class EventInfo : MemberInfo, _EventInfo {
  40                 AddEventAdapter cached_add_event;
  41
  42                 public abstract EventAttributes Attributes {get;}
  43
  44                 public
  45 #if NET_4_0
  46                 virtual
  47 #endif
  48                 Type EventHandlerType {
  49                         get {
  50                                 ParameterInfo[] p;
  51                                 MethodInfo add = GetAddMethod (true);
  52                                 p = add.GetParameters ();
  53                                 if (p.Length > 0) {
  54                                         Type t = p [0].ParameterType;
  55                                         /* is it alwasys the first arg?
  56                                         if (!t.IsSubclassOf (typeof (System.Delegate)))
  57                                                 throw new Exception ("no delegate in event");*/
  58                                         return t;
  59                                 } else
  60                                         return null;
  61                         }
  62                 }
  63
  64                 public
  65 #if NET_4_0
  66                 virtual
  67 #endif
  68                 bool IsMulticast {get {return true;}}
  69                 public bool IsSpecialName {get {return (Attributes & EventAttributes.SpecialName ) != 0;}}
  70                 public override MemberTypes MemberType {
  71                         get {return MemberTypes.Event;}
  72                 }
  73
  74                 protected EventInfo() {
  75                 }
  76
  77
  78                 [DebuggerHidden]
  79                 [DebuggerStepThrough]
  80                 public
  81 #if NET_4_0
  82                 virtual
  83 #endif
  84                 void AddEventHandler (object target, Delegate handler)
  85                 {
  86                         if (cached_add_event == null) {
  87                                 MethodInfo add = GetAddMethod ();
  88                                 if (add == null)
  89                                         throw new InvalidOperationException ("Cannot add a handler to an event that doesn't have a visible add method");
  90                                 if (add.DeclaringType.IsValueType) {
  91                                         if (target == null && !add.IsStatic)
  92                                                 throw new TargetException ("Cannot add a handler to a non static event with a null target");
  93                                         add.Invoke (target, new object [] {handler});
  94                                         return;
  95                                 }
  96                                 cached_add_event = CreateAddEventDelegate (add);
  97                         }
  98                         //if (target == null && is_instance)
  99                         //      throw new TargetException ("Cannot add a handler to a non static event with a null target");
 100                         cached_add_event (target, handler);
 101                 }
 102
 103                 public MethodInfo GetAddMethod() {
 104                         return GetAddMethod (false);
 105                 }
 106                 public abstract MethodInfo GetAddMethod(bool nonPublic);
 107                 public MethodInfo GetRaiseMethod() {
 108                         return GetRaiseMethod (false);
 109                 }
 110                 public abstract MethodInfo GetRaiseMethod( bool nonPublic);
 111                 public MethodInfo GetRemoveMethod() {
 112                         return GetRemoveMethod (false);
 113                 }
 114                 public abstract MethodInfo GetRemoveMethod( bool nonPublic);
 115
 116                 public virtual MethodInfo[] GetOtherMethods (bool nonPublic) {
 117                         // implemented by the derived class
 118                         return new MethodInfo [0];
 119                 }
 120
 121                 public MethodInfo[] GetOtherMethods () {
 122                         return GetOtherMethods (false);
 123                 }
 124
 125                 [DebuggerHidden]
 126                 [DebuggerStepThrough]
 127                 public
 128 #if NET_4_0
 129                 virtual
 130 #endif
 131                 void RemoveEventHandler (object target, Delegate handler)
 132                 {
 133                         MethodInfo remove = GetRemoveMethod ();
 134                         if (remove == null)
 135                                 throw new InvalidOperationException ("Cannot remove a handler to an event that doesn't have a visible remove method");
 136
 137                         remove.Invoke (target, new object [] {handler});
 138                 }
 139
 140 #if NET_4_0
 141                 public override bool Equals (object obj)
 142                 {
 143                         return obj == this;
 144                 }
 145
 146                 public override int GetHashCode ()
 147                 {
 148                         return base.GetHashCode ();
 149                 }
 150
 151                 public static bool operator == (EventInfo left, EventInfo right)
 152                 {
 153                         if ((object)left == (object)right)
 154                                 return true;
 155                         if ((object)left == null ^ (object)right == null)
 156                                 return false;
 157                         return left.Equals (right);
 158                 }
 159
 160                 public static bool operator != (EventInfo left, EventInfo right)
 161                 {
 162                         if ((object)left == (object)right)
 163                                 return false;
 164                         if ((object)left == null ^ (object)right == null)
 165                                 return true;
 166                         return !left.Equals (right);
 167                 }
 168 #endif
 169
 170                 void _EventInfo.GetIDsOfNames ([In] ref Guid riid, IntPtr rgszNames, uint cNames, uint lcid, IntPtr rgDispId)
 171                 {
 172                         throw new NotImplementedException ();
 173                 }
 174
 175                 void _EventInfo.GetTypeInfo (uint iTInfo, uint lcid, IntPtr ppTInfo)
 176                 {
 177                         throw new NotImplementedException ();
 178                 }
 179
 180                 void _EventInfo.GetTypeInfoCount (out uint pcTInfo)
 181                 {
 182                         throw new NotImplementedException ();
 183                 }
 184
 185                 void _EventInfo.Invoke (uint dispIdMember, [In] ref Guid riid, uint lcid, short wFlags, IntPtr pDispParams, IntPtr pVarResult, IntPtr pExcepInfo, IntPtr puArgErr)
 186                 {
 187                         throw new NotImplementedException ();
 188                 }
 189                 delegate void AddEventAdapter (object _this, Delegate dele);
 190                 delegate void AddEvent<T, D> (T _this, D dele);
 191                 delegate void StaticAddEvent<D> (D dele);
 192
 193 #pragma warning disable 169
 194                 // Used via reflection
 195                 static void AddEventFrame<T,D> (AddEvent<T,D> addEvent, object obj, object dele)
 196                 {
 197                         if (obj == null)
 198                                 throw new TargetException ("Cannot add a handler to a non static event with a null target");
 199                         if (!(obj is T))
 200                                 throw new TargetException ("Object doesn't match target");
 201                         addEvent ((T)obj, (D)dele);
 202                 }
 203
 204                 static void StaticAddEventAdapterFrame<D> (StaticAddEvent<D> addEvent, object obj, object dele)
 205                 {
 206                         addEvent ((D)dele);
 207                 }
 208 #pragma warning restore 169
 209
 210                 /*
 211                  * The idea behing this optimization is to use a pair of delegates to simulate the same effect of doing a reflection call.
 212                  * The first delegate performs casting and boxing, the second dispatch to the add_... method.
 213                  */
 214                 static AddEventAdapter CreateAddEventDelegate (MethodInfo method)
 215                 {
 216                         Type[] typeVector;
 217                         Type addHandlerType;
 218                         object addHandlerDelegate;
 219                         MethodInfo adapterFrame;
 220                         Type addHandlerDelegateType;
 221                         string frameName;
 222
 223                         if (method.IsStatic) {
 224                                 typeVector = new Type[] { method.GetParameters () [0].ParameterType };
 225                                 addHandlerDelegateType = typeof (StaticAddEvent<>);
 226                                 frameName = "StaticAddEventAdapterFrame";
 227                         } else {
 228                                 typeVector = new Type[] { method.DeclaringType, method.GetParameters () [0].ParameterType };
 229                                 addHandlerDelegateType = typeof (AddEvent<,>);
 230                                 frameName = "AddEventFrame";
 231                         }
 232
 233                         addHandlerType = addHandlerDelegateType.MakeGenericType (typeVector);
 234 #if NET_2_1
 235                         // with Silverlight a coreclr failure (e.g. Transparent caller creating a delegate on a Critical method)
 236                         // would normally throw an ArgumentException, so we set throwOnBindFailure to false and check for a null
 237                         // delegate that we can transform into a MethodAccessException
 238                         addHandlerDelegate = Delegate.CreateDelegate (addHandlerType, method, false);
 239                         if (addHandlerDelegate == null)
 240                                 throw new MethodAccessException ();
 241 #else
 242                         addHandlerDelegate = Delegate.CreateDelegate (addHandlerType, method);
 243 #endif
 244                         adapterFrame = typeof (EventInfo).GetMethod (frameName, BindingFlags.Static | BindingFlags.NonPublic);
 245                         adapterFrame = adapterFrame.MakeGenericMethod (typeVector);
 246                         return (AddEventAdapter)Delegate.CreateDelegate (typeof (AddEventAdapter), addHandlerDelegate, adapterFrame, true);
 247                 }
 248         }
 249 }