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                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
  44                 internal static extern object[] GetCustomAttributesInternal (ICustomAttributeProvider obj, bool pseudoAttrs);
  45
  46                 internal static object[] GetCustomAttributesBase (ICustomAttributeProvider obj)
  47                 {
  48                         object[] attrs = GetCustomAttributesInternal (obj, false);
  49
  50 #if NET_2_0 || BOOTSTRAP_NET_2_0
  51                         object[] pseudoAttrs = null;
  52
  53                         /* FIXME: Add other types */
  54                         if (obj is Type)
  55                                 pseudoAttrs = ((Type)obj).GetPseudoCustomAttributes ();
  56                         else if (obj is MonoMethod)
  57                                 pseudoAttrs = ((MonoMethod)obj).GetPseudoCustomAttributes ();
  58                         else if (obj is FieldInfo)
  59                                 pseudoAttrs = ((FieldInfo)obj).GetPseudoCustomAttributes ();
  60
  61                         if (pseudoAttrs != null) {
  62                                 object[] res = new object [attrs.Length + pseudoAttrs.Length];
  63                                 System.Array.Copy (attrs, res, attrs.Length);
  64                                 System.Array.Copy (pseudoAttrs, 0, res, attrs.Length, pseudoAttrs.Length);
  65                                 return res;
  66                         }
  67                         else
  68                                 return attrs;
  69 #else
  70                         return attrs;
  71 #endif
  72                 }
  73
  74                 internal static Attribute GetCustomAttribute (ICustomAttributeProvider obj,
  75                                                                 Type attributeType,
  76                                                                 bool inherit)
  77                 {
  78                         object[] res = GetCustomAttributes (obj, attributeType, inherit);
  79                         if (res.Length == 0)
  80                         {
  81                                 return null;
  82                         }
  83                         else if (res.Length > 1)
  84                         {
  85                                 string msg = "'{0}' has more than one attribute of type '{1}";
  86                                 msg = String.Format (msg, obj, attributeType);
  87                                 throw new AmbiguousMatchException (msg);
  88                         }
  89
  90                         return (Attribute) res[0];
  91                 }
  92
  93                 internal static object[] GetCustomAttributes (ICustomAttributeProvider obj, Type attributeType, bool inherit)
  94                 {
  95                         if (obj == null)
  96                                 throw new ArgumentNullException ("obj");
  97
  98                         object[] r;
  99                         object[] res = GetCustomAttributesBase (obj);
 100                         // shortcut
 101                         if (!inherit && res.Length == 1)
 102                         {
 103                                 if (attributeType != null)
 104                                 {
 105                                         if (attributeType.IsAssignableFrom (res[0].GetType ()))
 106                                         {
 107                                                 r = (object[]) Array.CreateInstance (attributeType, 1);
 108                                                 r[0] = res[0];
 109                                         }
 110                                         else
 111                                         {
 112                                                 r = (object[]) Array.CreateInstance (attributeType, 0);
 113                                         }
 114                                 }
 115                                 else
 116                                 {
 117                                         r = (object[]) Array.CreateInstance (res[0].GetType (), 1);
 118                                         r[0] = res[0];
 119                                 }
 120                                 return r;
 121                         }
 122
 123                         // if AttributeType is sealed, and Inherited is set to false, then
 124                         // there's no use in scanning base types
 125                         if ((attributeType != null && attributeType.IsSealed) && inherit)
 126                         {
 127                                 AttributeUsageAttribute usageAttribute = RetrieveAttributeUsage (
 128                                         attributeType);
 129                                 if (!usageAttribute.Inherited)
 130                                 {
 131                                         inherit = false;
 132                                 }
 133                         }
 134
 135                         int initialSize = res.Length < 16 ? res.Length : 16;
 136
 137                         Hashtable attributeInfos = new Hashtable (initialSize);
 138                         ArrayList a = new ArrayList (initialSize);
 139                         ICustomAttributeProvider btype = obj;
 140
 141                         int inheritanceLevel = 0;
 142
 143                         do
 144                         {
 145                                 foreach (object attr in res)
 146                                 {
 147                                         AttributeUsageAttribute usage;
 148
 149                                         Type attrType = attr.GetType ();
 150                                         if (attributeType != null)
 151                                         {
 152                                                 if (!attributeType.IsAssignableFrom (attrType))
 153                                                 {
 154                                                         continue;
 155                                                 }
 156                                         }
 157
 158                                         AttributeInfo firstAttribute = (AttributeInfo) attributeInfos[attrType];
 159                                         if (firstAttribute != null)
 160                                         {
 161                                                 usage = firstAttribute.Usage;
 162                                         }
 163                                         else
 164                                         {
 165                                                 usage = RetrieveAttributeUsage (attrType);
 166                                         }
 167
 168                                         // only add attribute to the list of attributes if
 169                                         // - we are on the first inheritance level, or the attribute can be inherited anyway
 170                                         // and (
 171                                         // - multiple attributes of the type are allowed
 172                                         // or (
 173                                         // - this is the first attribute we've discovered
 174                                         // or
 175                                         // - the attribute is on same inheritance level than the first
 176                                         //   attribute that was discovered for this attribute type ))
 177                                         if ((inheritanceLevel == 0 || usage.Inherited) && (usage.AllowMultiple ||
 178                                                 (firstAttribute == null || (firstAttribute != null
 179                                                         && firstAttribute.InheritanceLevel == inheritanceLevel))))
 180                                         {
 181                                                 a.Add (attr);
 182                                         }
 183
 184                                         if (firstAttribute == null)
 185                                         {
 186                                                 attributeInfos.Add (attrType, new AttributeInfo (usage, inheritanceLevel));
 187                                         }
 188                                 }
 189
 190                                 if ((btype = GetBase (btype)) != null)
 191                                 {
 192                                         inheritanceLevel++;
 193                                         res = GetCustomAttributesBase (btype);
 194                                 }
 195                         } while (inherit && btype != null);
 196
 197                         object[] array = null;
 198                         if (attributeType == null || attributeType.IsValueType)
 199                         {
 200                                 array = (object[]) Array.CreateInstance (typeof(Attribute), a.Count);
 201                         }
 202                         else
 203                         {
 204                                 array = Array.CreateInstance (attributeType, a.Count) as object[];
 205                         }
 206
 207                         // copy attributes to array
 208                         a.CopyTo (array, 0);
 209
 210                         return array;
 211                 }
 212
 213                 internal static object[] GetCustomAttributes (ICustomAttributeProvider obj, bool inherit)
 214                 {
 215                         if (obj == null)
 216                                 throw new ArgumentNullException ("obj");
 217
 218                         if (!inherit)
 219                                 return (object[]) GetCustomAttributesBase (obj).Clone ();
 220
 221                         return GetCustomAttributes (obj, null, inherit);
 222                 }
 223
 224                 internal static bool IsDefined (ICustomAttributeProvider obj, Type attributeType, bool inherit)
 225                 {
 226                         object [] res = GetCustomAttributesBase (obj);
 227                         foreach (object attr in res)
 228                                 if (attributeType.Equals (attr.GetType ()))
 229                                         return true;
 230
 231                         ICustomAttributeProvider btype;
 232                         if (inherit && ((btype = GetBase (obj)) != null))
 233                                 return IsDefined (btype, attributeType, inherit);
 234
 235                         return false;
 236                 }
 237
 238                 // Handles Type, MonoProperty and MonoMethod.
 239                 // The runtime has also cases for MonoEvent, MonoField, Assembly and ParameterInfo,
 240                 // but for those we return null here.
 241                 static ICustomAttributeProvider GetBase (ICustomAttributeProvider obj)
 242                 {
 243                         if (obj == null)
 244                                 return null;
 245
 246                         if (obj is Type)
 247                                 return ((Type) obj).BaseType;
 248
 249                         MethodInfo method = null;
 250                         if (obj is MonoProperty)
 251                         {
 252                                 MonoProperty prop = (MonoProperty) obj;
 253                                 method = prop.GetGetMethod (true);
 254                                 if (method == null)
 255                                         method = prop.GetSetMethod (true);
 256                         }
 257                         else if (obj is MonoMethod)
 258                         {
 259                                 method = (MethodInfo) obj;
 260                         }
 261
 262                         /**
 263                          * ParameterInfo -> null
 264                          * Assembly -> null
 265                          * MonoEvent -> null
 266                          * MonoField -> null
 267                          */
 268                         if (method == null || !method.IsVirtual)
 269                                 return null;
 270
 271                         MethodInfo baseMethod = method.GetBaseDefinition ();
 272                         if (baseMethod == method)
 273                                 return null;
 274
 275                         return baseMethod;
 276                 }
 277
 278                 private static AttributeUsageAttribute RetrieveAttributeUsage (Type attributeType)
 279                 {
 280                         if (attributeType == typeof (AttributeUsageAttribute))
 281                                 /* Avoid endless recursion */
 282                                 return new AttributeUsageAttribute (AttributeTargets.Class);
 283
 284                         AttributeUsageAttribute usageAttribute = null;
 285                         object[] attribs = GetCustomAttributes (attributeType,
 286                                 MonoCustomAttrs.AttributeUsageType, false);
 287                         if (attribs.Length == 0)
 288                         {
 289                                 // if no AttributeUsage was defined on the attribute level, then
 290                                 // try to retrieve if from its base type
 291                                 if (attributeType.BaseType != null)
 292                                 {
 293                                         usageAttribute = RetrieveAttributeUsage (attributeType.BaseType);
 294
 295                                 }
 296                                 if (usageAttribute != null)
 297                                 {
 298                                         // return AttributeUsage of base class
 299                                         return usageAttribute;
 300
 301                                 }
 302                                 // return default AttributeUsageAttribute if no AttributeUsage
 303                                 // was defined on attribute, or its base class
 304                                 return DefaultAttributeUsage;
 305                         }
 306                         // check if more than one AttributeUsageAttribute has been specified
 307                         // on the type
 308                         // NOTE: compilers should prevent this, but that doesn't prevent
 309                         // anyone from using IL ofcourse
 310                         if (attribs.Length > 1)
 311                         {
 312                                 throw new FormatException ("Duplicate AttributeUsageAttribute cannot be specified on an attribute type.");
 313                         }
 314
 315                         return ((AttributeUsageAttribute) attribs[0]);
 316                 }
 317
 318                 private static readonly Type AttributeUsageType = typeof(AttributeUsageAttribute);
 319                 private static readonly AttributeUsageAttribute DefaultAttributeUsage =
 320                         new AttributeUsageAttribute (AttributeTargets.All);
 321
 322                 private class AttributeInfo
 323                 {
 324                         private AttributeUsageAttribute _usage;
 325                         private int _inheritanceLevel;
 326
 327                         public AttributeInfo (AttributeUsageAttribute usage, int inheritanceLevel)
 328                         {
 329                                 _usage = usage;
 330                                 _inheritanceLevel = inheritanceLevel;
 331                         }
 332
 333                         public AttributeUsageAttribute Usage
 334                         {
 335                                 get
 336                                 {
 337                                         return _usage;
 338                                 }
 339                         }
 340
 341                         public int InheritanceLevel
 342                         {
 343                                 get
 344                                 {
 345                                         return _inheritanceLevel;
 346                                 }
 347                         }
 348                 }
 349         }
 350 }
 351