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 //
  12 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  13 //
  14 // Permission is hereby granted, free of charge, to any person obtaining
  15 // a copy of this software and associated documentation files (the
  16 // "Software"), to deal in the Software without restriction, including
  17 // without limitation the rights to use, copy, modify, merge, publish,
  18 // distribute, sublicense, and/or sell copies of the Software, and to
  19 // permit persons to whom the Software is furnished to do so, subject to
  20 // the following conditions:
  21 //
  22 // The above copyright notice and this permission notice shall be
  23 // included in all copies or substantial portions of the Software.
  24 //
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32 //
  33
  34 using System;
  35 using System.Reflection;
  36 using System.Collections;
  37 using System.Runtime.CompilerServices;
  38
  39 namespace System
  40 {
  41         internal class MonoCustomAttrs
  42         {
  43 #if NET_2_0 || BOOTSTRAP_NET_2_0
  44                 internal static readonly bool pseudoAttrs = true;
  45 #else
  46                 internal static readonly bool pseudoAttrs = false;
  47 #endif
  48
  49                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
  50                 internal static extern object[] GetCustomAttributesInternal (ICustomAttributeProvider obj, bool pseudoAttrs);
  51
  52                 internal static Attribute GetCustomAttribute (ICustomAttributeProvider obj,
  53                                                                 Type attributeType,
  54                                                                 bool inherit)
  55                 {
  56                         object[] res = GetCustomAttributes (obj, attributeType, inherit);
  57                         if (res.Length == 0)
  58                         {
  59                                 return null;
  60                         }
  61                         else if (res.Length > 1)
  62                         {
  63                                 string msg = "'{0}' has more than one attribute of type '{1}";
  64                                 msg = String.Format (msg, obj, attributeType);
  65                                 throw new AmbiguousMatchException (msg);
  66                         }
  67
  68                         return (Attribute) res[0];
  69                 }
  70
  71                 internal static object[] GetCustomAttributes (ICustomAttributeProvider obj, Type attributeType, bool inherit)
  72                 {
  73                         if (obj == null)
  74                                 throw new ArgumentNullException ("obj");
  75
  76                         object[] r;
  77                         object[] res = GetCustomAttributesInternal (obj, pseudoAttrs);
  78                         // shortcut
  79                         if (!inherit && res.Length == 1)
  80                         {
  81                                 if (attributeType != null)
  82                                 {
  83                                         if (attributeType.IsAssignableFrom (res[0].GetType ()))
  84                                         {
  85                                                 r = (object[]) Array.CreateInstance (attributeType, 1);
  86                                                 r[0] = res[0];
  87                                         }
  88                                         else
  89                                         {
  90                                                 r = (object[]) Array.CreateInstance (attributeType, 0);
  91                                         }
  92                                 }
  93                                 else
  94                                 {
  95                                         r = (object[]) Array.CreateInstance (res[0].GetType (), 1);
  96                                         r[0] = res[0];
  97                                 }
  98                                 return r;
  99                         }
 100
 101                         // if AttributeType is sealed, and Inherited is set to false, then
 102                         // there's no use in scanning base types
 103                         if ((attributeType != null && attributeType.IsSealed) && !inherit)
 104                         {
 105                                 AttributeUsageAttribute usageAttribute = RetrieveAttributeUsage (
 106                                         attributeType);
 107                                 if (!usageAttribute.Inherited)
 108                                 {
 109                                         inherit = false;
 110                                 }
 111                         }
 112
 113                         int initialSize = res.Length < 16 ? res.Length : 16;
 114
 115                         Hashtable attributeInfos = new Hashtable (initialSize);
 116                         ArrayList a = new ArrayList (initialSize);
 117                         ICustomAttributeProvider btype = obj;
 118
 119                         int inheritanceLevel = 0;
 120
 121                         do
 122                         {
 123                                 foreach (object attr in res)
 124                                 {
 125                                         AttributeUsageAttribute usage;
 126
 127                                         Type attrType = attr.GetType ();
 128                                         if (attributeType != null)
 129                                         {
 130                                                 if (!attributeType.IsAssignableFrom (attrType))
 131                                                 {
 132                                                         continue;
 133                                                 }
 134                                         }
 135
 136                                         AttributeInfo firstAttribute = (AttributeInfo) attributeInfos[attrType];
 137                                         if (firstAttribute != null)
 138                                         {
 139                                                 usage = firstAttribute.Usage;
 140                                         }
 141                                         else
 142                                         {
 143                                                 usage = RetrieveAttributeUsage (attrType);
 144                                         }
 145
 146                                         // only add attribute to the list of attributes if
 147                                         // - we are on the first inheritance level, or the attribute can be inherited anyway
 148                                         // and (
 149                                         // - multiple attributes of the type are allowed
 150                                         // or (
 151                                         // - this is the first attribute we've discovered
 152                                         // or
 153                                         // - the attribute is on same inheritance level than the first
 154                                         //   attribute that was discovered for this attribute type ))
 155                                         if ((inheritanceLevel == 0 || usage.Inherited) && (usage.AllowMultiple ||
 156                                                 (firstAttribute == null || (firstAttribute != null
 157                                                         && firstAttribute.InheritanceLevel == inheritanceLevel))))
 158                                         {
 159                                                 a.Add (attr);
 160                                         }
 161
 162                                         if (firstAttribute == null)
 163                                         {
 164                                                 attributeInfos.Add (attrType, new AttributeInfo (usage, inheritanceLevel));
 165                                         }
 166                                 }
 167
 168                                 if ((btype = GetBase (btype)) != null)
 169                                 {
 170                                         inheritanceLevel++;
 171                                         res = GetCustomAttributesInternal (btype, pseudoAttrs);
 172                                 }
 173                         } while (inherit && btype != null);
 174
 175                         object[] array = null;
 176                         if (attributeType == null || attributeType.IsValueType)
 177                         {
 178                                 array = (object[]) Array.CreateInstance (typeof(Attribute), a.Count);
 179                         }
 180                         else
 181                         {
 182                                 array = Array.CreateInstance (attributeType, a.Count) as object[];
 183                         }
 184
 185                         // copy attributes to array
 186                         a.CopyTo (array, 0);
 187
 188                         return array;
 189                 }
 190
 191                 internal static object[] GetCustomAttributes (ICustomAttributeProvider obj, bool inherit)
 192                 {
 193                         if (obj == null)
 194                                 throw new ArgumentNullException ("obj");
 195
 196                         if (!inherit)
 197                                 return (object[]) GetCustomAttributesInternal (obj, pseudoAttrs).Clone ();
 198
 199                         return GetCustomAttributes (obj, null, inherit);
 200                 }
 201
 202                 internal static bool IsDefined (ICustomAttributeProvider obj, Type attributeType, bool inherit)
 203                 {
 204                         object [] res = GetCustomAttributesInternal (obj, pseudoAttrs);
 205                         foreach (object attr in res)
 206                                 if (attributeType.Equals (attr.GetType ()))
 207                                         return true;
 208
 209                         ICustomAttributeProvider btype;
 210                         if (inherit && ((btype = GetBase (obj)) != null))
 211                                 return IsDefined (btype, attributeType, inherit);
 212
 213                         return false;
 214                 }
 215
 216                 // Handles Type, MonoProperty and MonoMethod.
 217                 // The runtime has also cases for MonoEvent, MonoField, Assembly and ParameterInfo,
 218                 // but for those we return null here.
 219                 static ICustomAttributeProvider GetBase (ICustomAttributeProvider obj)
 220                 {
 221                         if (obj == null)
 222                                 return null;
 223
 224                         if (obj is Type)
 225                                 return ((Type) obj).BaseType;
 226
 227                         MethodInfo method = null;
 228                         if (obj is MonoProperty)
 229                         {
 230                                 MonoProperty prop = (MonoProperty) obj;
 231                                 method = prop.GetGetMethod (true);
 232                                 if (method == null)
 233                                         method = prop.GetSetMethod (true);
 234                         }
 235                         else if (obj is MonoMethod)
 236                         {
 237                                 method = (MethodInfo) obj;
 238                         }
 239
 240                         /**
 241                          * ParameterInfo -> null
 242                          * Assembly -> null
 243                          * MonoEvent -> null
 244                          * MonoField -> null
 245                          */
 246                         if (method == null || !method.IsVirtual)
 247                                 return null;
 248
 249                         MethodInfo baseMethod = method.GetBaseDefinition ();
 250                         if (baseMethod == method)
 251                                 return null;
 252
 253                         return baseMethod;
 254                 }
 255
 256                 private static AttributeUsageAttribute RetrieveAttributeUsage (Type attributeType)
 257                 {
 258                         AttributeUsageAttribute usageAttribute = null;
 259                         object[] attribs = GetCustomAttributes (attributeType,
 260                                 MonoCustomAttrs.AttributeUsageType, false);
 261                         if (attribs.Length == 0)
 262                         {
 263                                 // if no AttributeUsage was defined on the attribute level, then
 264                                 // try to retrieve if from its base type
 265                                 if (attributeType.BaseType != null)
 266                                 {
 267                                         usageAttribute = RetrieveAttributeUsage (attributeType.BaseType);
 268
 269                                 }
 270                                 if (usageAttribute != null)
 271                                 {
 272                                         // return AttributeUsage of base class
 273                                         return usageAttribute;
 274
 275                                 }
 276                                 // return default AttributeUsageAttribute if no AttributeUsage
 277                                 // was defined on attribute, or its base class
 278                                 return DefaultAttributeUsage;
 279                         }
 280                         // check if more than one AttributeUsageAttribute has been specified
 281                         // on the type
 282                         // NOTE: compilers should prevent this, but that doesn't prevent
 283                         // anyone from using IL ofcourse
 284                         if (attribs.Length > 1)
 285                         {
 286                                 throw new FormatException ("Duplicate AttributeUsageAttribute cannot be specified on an attribute type.");
 287                         }
 288
 289                         return ((AttributeUsageAttribute) attribs[0]);
 290                 }
 291
 292                 private static readonly Type AttributeUsageType = typeof(AttributeUsageAttribute);
 293                 private static readonly AttributeUsageAttribute DefaultAttributeUsage =
 294                         new AttributeUsageAttribute (AttributeTargets.All);
 295
 296                 private class AttributeInfo
 297                 {
 298                         private AttributeUsageAttribute _usage;
 299                         private int _inheritanceLevel;
 300
 301                         public AttributeInfo (AttributeUsageAttribute usage, int inheritanceLevel)
 302                         {
 303                                 _usage = usage;
 304                                 _inheritanceLevel = inheritanceLevel;
 305                         }
 306
 307                         public AttributeUsageAttribute Usage
 308                         {
 309                                 get
 310                                 {
 311                                         return _usage;
 312                                 }
 313                         }
 314
 315                         public int InheritanceLevel
 316                         {
 317                                 get
 318                                 {
 319                                         return _inheritanceLevel;
 320                                 }
 321                         }
 322                 }
 323         }
 324 }
 325