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                         else if (obj is ParameterInfo)
  61                                 pseudoAttrs = ((ParameterInfo)obj).GetPseudoCustomAttributes ();
  62
  63                         if (pseudoAttrs != null) {
  64                                 object[] res = new object [attrs.Length + pseudoAttrs.Length];
  65                                 System.Array.Copy (attrs, res, attrs.Length);
  66                                 System.Array.Copy (pseudoAttrs, 0, res, attrs.Length, pseudoAttrs.Length);
  67                                 return res;
  68                         }
  69                         else
  70                                 return attrs;
  71 #else
  72                         return attrs;
  73 #endif
  74                 }
  75
  76                 internal static Attribute GetCustomAttribute (ICustomAttributeProvider obj,
  77                                                                 Type attributeType,
  78                                                                 bool inherit)
  79                 {
  80                         object[] res = GetCustomAttributes (obj, attributeType, inherit);
  81                         if (res.Length == 0)
  82                         {
  83                                 return null;
  84                         }
  85                         else if (res.Length > 1)
  86                         {
  87                                 string msg = "'{0}' has more than one attribute of type '{1}";
  88                                 msg = String.Format (msg, obj, attributeType);
  89                                 throw new AmbiguousMatchException (msg);
  90                         }
  91
  92                         return (Attribute) res[0];
  93                 }
  94
  95                 internal static object[] GetCustomAttributes (ICustomAttributeProvider obj, Type attributeType, bool inherit)
  96                 {
  97                         if (obj == null)
  98                                 throw new ArgumentNullException ("obj");
  99
 100                         object[] r;
 101                         object[] res = GetCustomAttributesBase (obj);
 102                         // shortcut
 103                         if (!inherit && res.Length == 1)
 104                         {
 105                                 if (attributeType != null)
 106                                 {
 107                                         if (attributeType.IsAssignableFrom (res[0].GetType ()))
 108                                         {
 109                                                 r = (object[]) Array.CreateInstance (attributeType, 1);
 110                                                 r[0] = res[0];
 111                                         }
 112                                         else
 113                                         {
 114                                                 r = (object[]) Array.CreateInstance (attributeType, 0);
 115                                         }
 116                                 }
 117                                 else
 118                                 {
 119                                         r = (object[]) Array.CreateInstance (res[0].GetType (), 1);
 120                                         r[0] = res[0];
 121                                 }
 122                                 return r;
 123                         }
 124
 125                         // if AttributeType is sealed, and Inherited is set to false, then
 126                         // there's no use in scanning base types
 127                         if ((attributeType != null && attributeType.IsSealed) && inherit)
 128                         {
 129                                 AttributeUsageAttribute usageAttribute = RetrieveAttributeUsage (
 130                                         attributeType);
 131                                 if (!usageAttribute.Inherited)
 132                                 {
 133                                         inherit = false;
 134                                 }
 135                         }
 136
 137                         int initialSize = res.Length < 16 ? res.Length : 16;
 138
 139                         Hashtable attributeInfos = new Hashtable (initialSize);
 140                         ArrayList a = new ArrayList (initialSize);
 141                         ICustomAttributeProvider btype = obj;
 142
 143                         int inheritanceLevel = 0;
 144
 145                         do
 146                         {
 147                                 foreach (object attr in res)
 148                                 {
 149                                         AttributeUsageAttribute usage;
 150
 151                                         Type attrType = attr.GetType ();
 152                                         if (attributeType != null)
 153                                         {
 154                                                 if (!attributeType.IsAssignableFrom (attrType))
 155                                                 {
 156                                                         continue;
 157                                                 }
 158                                         }
 159
 160                                         AttributeInfo firstAttribute = (AttributeInfo) attributeInfos[attrType];
 161                                         if (firstAttribute != null)
 162                                         {
 163                                                 usage = firstAttribute.Usage;
 164                                         }
 165                                         else
 166                                         {
 167                                                 usage = RetrieveAttributeUsage (attrType);
 168                                         }
 169
 170                                         // only add attribute to the list of attributes if
 171                                         // - we are on the first inheritance level, or the attribute can be inherited anyway
 172                                         // and (
 173                                         // - multiple attributes of the type are allowed
 174                                         // or (
 175                                         // - this is the first attribute we've discovered
 176                                         // or
 177                                         // - the attribute is on same inheritance level than the first
 178                                         //   attribute that was discovered for this attribute type ))
 179                                         if ((inheritanceLevel == 0 || usage.Inherited) && (usage.AllowMultiple ||
 180                                                 (firstAttribute == null || (firstAttribute != null
 181                                                         && firstAttribute.InheritanceLevel == inheritanceLevel))))
 182                                         {
 183                                                 a.Add (attr);
 184                                         }
 185
 186                                         if (firstAttribute == null)
 187                                         {
 188                                                 attributeInfos.Add (attrType, new AttributeInfo (usage, inheritanceLevel));
 189                                         }
 190                                 }
 191
 192                                 if ((btype = GetBase (btype)) != null)
 193                                 {
 194                                         inheritanceLevel++;
 195                                         res = GetCustomAttributesBase (btype);
 196                                 }
 197                         } while (inherit && btype != null);
 198
 199                         object[] array = null;
 200                         if (attributeType == null || attributeType.IsValueType)
 201                         {
 202                                 array = (object[]) Array.CreateInstance (typeof(Attribute), a.Count);
 203                         }
 204                         else
 205                         {
 206                                 array = Array.CreateInstance (attributeType, a.Count) as object[];
 207                         }
 208
 209                         // copy attributes to array
 210                         a.CopyTo (array, 0);
 211
 212                         return array;
 213                 }
 214
 215                 internal static object[] GetCustomAttributes (ICustomAttributeProvider obj, bool inherit)
 216                 {
 217                         if (obj == null)
 218                                 throw new ArgumentNullException ("obj");
 219
 220                         if (!inherit)
 221                                 return (object[]) GetCustomAttributesBase (obj).Clone ();
 222
 223                         return GetCustomAttributes (obj, null, inherit);
 224                 }
 225
 226                 internal static bool IsDefined (ICustomAttributeProvider obj, Type attributeType, bool inherit)
 227                 {
 228                         object [] res = GetCustomAttributesBase (obj);
 229                         foreach (object attr in res)
 230                                 if (attributeType.Equals (attr.GetType ()))
 231                                         return true;
 232
 233                         ICustomAttributeProvider btype;
 234                         if (inherit && ((btype = GetBase (obj)) != null))
 235                                 return IsDefined (btype, attributeType, inherit);
 236
 237                         return false;
 238                 }
 239
 240                 // Handles Type, MonoProperty and MonoMethod.
 241                 // The runtime has also cases for MonoEvent, MonoField, Assembly and ParameterInfo,
 242                 // but for those we return null here.
 243                 static ICustomAttributeProvider GetBase (ICustomAttributeProvider obj)
 244                 {
 245                         if (obj == null)
 246                                 return null;
 247
 248                         if (obj is Type)
 249                                 return ((Type) obj).BaseType;
 250
 251                         MethodInfo method = null;
 252                         if (obj is MonoProperty)
 253                         {
 254                                 MonoProperty prop = (MonoProperty) obj;
 255                                 method = prop.GetGetMethod (true);
 256                                 if (method == null)
 257                                         method = prop.GetSetMethod (true);
 258                         }
 259                         else if (obj is MonoMethod)
 260                         {
 261                                 method = (MethodInfo) obj;
 262                         }
 263
 264                         /**
 265                          * ParameterInfo -> null
 266                          * Assembly -> null
 267                          * MonoEvent -> null
 268                          * MonoField -> null
 269                          */
 270                         if (method == null || !method.IsVirtual)
 271                                 return null;
 272
 273                         MethodInfo baseMethod = method.GetBaseDefinition ();
 274                         if (baseMethod == method)
 275                                 return null;
 276
 277                         return baseMethod;
 278                 }
 279
 280                 private static AttributeUsageAttribute RetrieveAttributeUsage (Type attributeType)
 281                 {
 282                         if (attributeType == typeof (AttributeUsageAttribute))
 283                                 /* Avoid endless recursion */
 284                                 return new AttributeUsageAttribute (AttributeTargets.Class);
 285
 286                         AttributeUsageAttribute usageAttribute = null;
 287                         object[] attribs = GetCustomAttributes (attributeType,
 288                                 MonoCustomAttrs.AttributeUsageType, false);
 289                         if (attribs.Length == 0)
 290                         {
 291                                 // if no AttributeUsage was defined on the attribute level, then
 292                                 // try to retrieve if from its base type
 293                                 if (attributeType.BaseType != null)
 294                                 {
 295                                         usageAttribute = RetrieveAttributeUsage (attributeType.BaseType);
 296
 297                                 }
 298                                 if (usageAttribute != null)
 299                                 {
 300                                         // return AttributeUsage of base class
 301                                         return usageAttribute;
 302
 303                                 }
 304                                 // return default AttributeUsageAttribute if no AttributeUsage
 305                                 // was defined on attribute, or its base class
 306                                 return DefaultAttributeUsage;
 307                         }
 308                         // check if more than one AttributeUsageAttribute has been specified
 309                         // on the type
 310                         // NOTE: compilers should prevent this, but that doesn't prevent
 311                         // anyone from using IL ofcourse
 312                         if (attribs.Length > 1)
 313                         {
 314                                 throw new FormatException ("Duplicate AttributeUsageAttribute cannot be specified on an attribute type.");
 315                         }
 316
 317                         return ((AttributeUsageAttribute) attribs[0]);
 318                 }
 319
 320                 private static readonly Type AttributeUsageType = typeof(AttributeUsageAttribute);
 321                 private static readonly AttributeUsageAttribute DefaultAttributeUsage =
 322                         new AttributeUsageAttribute (AttributeTargets.All);
 323
 324                 private class AttributeInfo
 325                 {
 326                         private AttributeUsageAttribute _usage;
 327                         private int _inheritanceLevel;
 328
 329                         public AttributeInfo (AttributeUsageAttribute usage, int inheritanceLevel)
 330                         {
 331                                 _usage = usage;
 332                                 _inheritanceLevel = inheritanceLevel;
 333                         }
 334
 335                         public AttributeUsageAttribute Usage
 336                         {
 337                                 get
 338                                 {
 339                                         return _usage;
 340                                 }
 341                         }
 342
 343                         public int InheritanceLevel
 344                         {
 345                                 get
 346                                 {
 347                                         return _inheritanceLevel;
 348                                 }
 349                         }
 350                 }
 351         }
 352 }
 353