mcs/class/corlib/System/MonoCustomAttrs.cs

   1 // System.MonoCustomAttrs.cs
   2 // Hooks into the runtime to get custom attributes for reflection handles
   3 //
   4 // Authors:
   5 //      Paolo Molaro (lupus@ximian.com)
   6 //      Gonzalo Paniagua Javier (gonzalo@ximian.com)
   7 //
   8 // (c) 2002,2003 Ximian, Inc. (http://www.ximian.com)
   9 //
  10
  11 using System;
  12 using System.Reflection;
  13 using System.Collections;
  14 using System.Runtime.CompilerServices;
  15
  16 namespace System {
  17         internal class MonoCustomAttrs {
  18
  19                 static Hashtable handle_to_attrs = new Hashtable ();
  20
  21                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  22                 internal static extern object[] GetCustomAttributes (ICustomAttributeProvider obj);
  23
  24                 private static object[] from_cache (ICustomAttributeProvider obj)
  25                 {
  26                         object[] res = (object []) handle_to_attrs [obj];
  27                         if (res != null)
  28                                 return res;
  29                         res = GetCustomAttributes (obj);
  30                         handle_to_attrs.Add (obj, res);
  31                         return res;
  32                 }
  33
  34                 internal static object[] GetCustomAttributes (ICustomAttributeProvider obj, Type attributeType, bool inherit)
  35                 {
  36                         if (obj == null)
  37                                 return (object []) Array.CreateInstance (attributeType, 0);
  38
  39                         object[] r;
  40                         object[] res = from_cache (obj);
  41                         // shortcut
  42                         if (!inherit && res.Length == 1) {
  43                                 if (attributeType.IsAssignableFrom (res[0].GetType ())) {
  44                                         r = (object []) Array.CreateInstance (attributeType, 1);
  45                                         r [0] = res [0];
  46                                 } else {
  47                                         r = (object []) Array.CreateInstance (attributeType, 0);
  48                                 }
  49                                 return r;
  50                         }
  51
  52                         ArrayList a = new ArrayList ();
  53                         ICustomAttributeProvider btype = obj;
  54                         do {
  55                                 foreach (object attr in res)
  56                                         if (attributeType.IsAssignableFrom (attr.GetType ()))
  57                                                 a.Add (attr);
  58
  59                                 if ((btype = GetBase (btype)) != null)
  60                                         res = from_cache (btype);
  61                         } while (inherit && btype != null);
  62
  63                         return (object []) a.ToArray (attributeType);
  64                 }
  65
  66                 internal static object [] GetCustomAttributes (ICustomAttributeProvider obj, bool inherit)
  67                 {
  68                         if (obj == null)
  69                                 return new object [0]; //FIXME: Should i throw an exception here?
  70
  71                         if (!inherit)
  72                                 return (object []) from_cache (obj).Clone ();
  73
  74                         ArrayList a = new ArrayList ();
  75                         ICustomAttributeProvider btype = obj;
  76                         a.AddRange (from_cache (btype));
  77                         while ((btype = GetBase (btype)) != null)
  78                                 a.AddRange (from_cache (btype));
  79
  80                         return (object []) a.ToArray (typeof (Attribute));
  81                 }
  82
  83                 internal static bool IsDefined (ICustomAttributeProvider obj, Type attributeType, bool inherit)
  84                 {
  85                         object[] res = from_cache (obj);
  86                         foreach (object attr in res) {
  87                                 if (attributeType.Equals (attr.GetType ()))
  88                                         return true;
  89                         }
  90
  91                         ICustomAttributeProvider btype = GetBase (obj);
  92                         if (inherit && (btype != null))
  93                                 return IsDefined (btype, attributeType, inherit);
  94
  95                         return false;
  96                 }
  97
  98                 // Handles Type, MonoProperty and MonoMethod.
  99                 // The runtime has also cases for MonoEvent, MonoField, Assembly and ParameterInfo,
 100                 // but for those we return null here.
 101                 static ICustomAttributeProvider GetBase (ICustomAttributeProvider obj)
 102                 {
 103                         if (obj == null)
 104                                 return null;
 105
 106                         if (obj is Type)
 107                                 return ((Type) obj).BaseType;
 108
 109                         MethodInfo method = null;
 110                         if (obj is MonoProperty) {
 111                                 MonoProperty prop = (MonoProperty) obj;
 112                                 method = prop.GetGetMethod ();
 113                                 if (method == null)
 114                                         method = prop.GetSetMethod ();
 115                         } else if (obj is MonoMethod) {
 116                                 method = (MethodInfo) obj;
 117                         }
 118
 119                         /**
 120                          * ParameterInfo -> null
 121                          * Assembly -> null
 122                          * MonoEvent -> null
 123                          * MonoField -> null
 124                          */
 125                         if (method == null || !method.IsVirtual)
 126                                 return null;
 127
 128                         MethodInfo baseMethod = method.GetBaseDefinition ();
 129                         if (baseMethod == method)
 130                                 return null;
 131
 132                         return baseMethod;
 133                 }
 134         }
 135 }
 136