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