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 #if  NET_2_0
  40 using System.Collections.Generic;
  41 #endif
  42
  43 namespace System
  44 {
  45         internal class MonoCustomAttrs
  46         {
  47                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
  48                 internal static extern object[] GetCustomAttributesInternal (ICustomAttributeProvider obj, Type attributeType, bool pseudoAttrs);
  49
  50                 internal static object[] GetPseudoCustomAttributes (ICustomAttributeProvider obj, Type attributeType) {
  51 #if NET_2_0 || BOOTSTRAP_NET_2_0
  52                         object[] pseudoAttrs = null;
  53
  54                         /* FIXME: Add other types */
  55                         if (obj is MonoMethod)
  56                                 pseudoAttrs = ((MonoMethod)obj).GetPseudoCustomAttributes ();
  57                         else if (obj is FieldInfo)
  58                                 pseudoAttrs = ((FieldInfo)obj).GetPseudoCustomAttributes ();
  59                         else if (obj is ParameterInfo)
  60                                 pseudoAttrs = ((ParameterInfo)obj).GetPseudoCustomAttributes ();
  61                         else if (obj is Type)
  62                                 pseudoAttrs = ((Type)obj).GetPseudoCustomAttributes ();
  63
  64                         if ((attributeType != null) && (pseudoAttrs != null)) {
  65                                 for (int i = 0; i < pseudoAttrs.Length; ++i)
  66                                         if (attributeType.IsAssignableFrom (pseudoAttrs [i].GetType ()))
  67                                                 if (pseudoAttrs.Length == 1)
  68                                                         return pseudoAttrs;
  69                                                 else
  70                                                         return new object [] { pseudoAttrs [i] };
  71                                 return new object [0];
  72                         }
  73                         else
  74                                 return pseudoAttrs;
  75 #else
  76                         return null;
  77 #endif
  78                 }
  79
  80                 internal static object[] GetCustomAttributesBase (ICustomAttributeProvider obj, Type attributeType)
  81                 {
  82                         object[] attrs = GetCustomAttributesInternal (obj, attributeType, false);
  83
  84                         object[] pseudoAttrs = GetPseudoCustomAttributes (obj, attributeType);
  85                         if (pseudoAttrs != null) {
  86                                 object[] res = new object [attrs.Length + pseudoAttrs.Length];
  87                                 System.Array.Copy (attrs, res, attrs.Length);
  88                                 System.Array.Copy (pseudoAttrs, 0, res, attrs.Length, pseudoAttrs.Length);
  89                                 return res;
  90                         }
  91                         else
  92                                 return attrs;
  93                 }
  94
  95                 internal static Attribute GetCustomAttribute (ICustomAttributeProvider obj,
  96                                                                 Type attributeType,
  97                                                                 bool inherit)
  98                 {
  99                         object[] res = GetCustomAttributes (obj, attributeType, inherit);
 100                         if (res.Length == 0)
 101                         {
 102                                 return null;
 103                         }
 104                         else if (res.Length > 1)
 105                         {
 106                                 string msg = "'{0}' has more than one attribute of type '{1}";
 107                                 msg = String.Format (msg, obj, attributeType);
 108                                 throw new AmbiguousMatchException (msg);
 109                         }
 110
 111                         return (Attribute) res[0];
 112                 }
 113
 114                 internal static object[] GetCustomAttributes (ICustomAttributeProvider obj, Type attributeType, bool inherit)
 115                 {
 116                         if (obj == null)
 117                                 throw new ArgumentNullException ("obj");
 118
 119                         object[] r;
 120                         object[] res = GetCustomAttributesBase (obj, attributeType);
 121                         // shortcut
 122                         if (!inherit && res.Length == 1)
 123                         {
 124                                 if (attributeType != null)
 125                                 {
 126                                         if (attributeType.IsAssignableFrom (res[0].GetType ()))
 127                                         {
 128                                                 r = (object[]) Array.CreateInstance (attributeType, 1);
 129                                                 r[0] = res[0];
 130                                         }
 131                                         else
 132                                         {
 133                                                 r = (object[]) Array.CreateInstance (attributeType, 0);
 134                                         }
 135                                 }
 136                                 else
 137                                 {
 138                                         r = (object[]) Array.CreateInstance (res[0].GetType (), 1);
 139                                         r[0] = res[0];
 140                                 }
 141                                 return r;
 142                         }
 143
 144                         // if AttributeType is sealed, and Inherited is set to false, then
 145                         // there's no use in scanning base types
 146                         if ((attributeType != null && attributeType.IsSealed) && inherit)
 147                         {
 148                                 AttributeUsageAttribute usageAttribute = RetrieveAttributeUsage (
 149                                         attributeType);
 150                                 if (!usageAttribute.Inherited)
 151                                 {
 152                                         inherit = false;
 153                                 }
 154                         }
 155
 156                         int initialSize = res.Length < 16 ? res.Length : 16;
 157
 158                         Hashtable attributeInfos = new Hashtable (initialSize);
 159                         ArrayList a = new ArrayList (initialSize);
 160                         ICustomAttributeProvider btype = obj;
 161
 162                         int inheritanceLevel = 0;
 163
 164                         do
 165                         {
 166                                 foreach (object attr in res)
 167                                 {
 168                                         AttributeUsageAttribute usage;
 169
 170                                         Type attrType = attr.GetType ();
 171                                         if (attributeType != null)
 172                                         {
 173                                                 if (!attributeType.IsAssignableFrom (attrType))
 174                                                 {
 175                                                         continue;
 176                                                 }
 177                                         }
 178
 179                                         AttributeInfo firstAttribute = (AttributeInfo) attributeInfos[attrType];
 180                                         if (firstAttribute != null)
 181                                         {
 182                                                 usage = firstAttribute.Usage;
 183                                         }
 184                                         else
 185                                         {
 186                                                 usage = RetrieveAttributeUsage (attrType);
 187                                         }
 188
 189                                         // only add attribute to the list of attributes if
 190                                         // - we are on the first inheritance level, or the attribute can be inherited anyway
 191                                         // and (
 192                                         // - multiple attributes of the type are allowed
 193                                         // or (
 194                                         // - this is the first attribute we've discovered
 195                                         // or
 196                                         // - the attribute is on same inheritance level than the first
 197                                         //   attribute that was discovered for this attribute type ))
 198                                         if ((inheritanceLevel == 0 || usage.Inherited) && (usage.AllowMultiple ||
 199                                                 (firstAttribute == null || (firstAttribute != null
 200                                                         && firstAttribute.InheritanceLevel == inheritanceLevel))))
 201                                         {
 202                                                 a.Add (attr);
 203                                         }
 204
 205                                         if (firstAttribute == null)
 206                                         {
 207                                                 attributeInfos.Add (attrType, new AttributeInfo (usage, inheritanceLevel));
 208                                         }
 209                                 }
 210
 211                                 if ((btype = GetBase (btype)) != null)
 212                                 {
 213                                         inheritanceLevel++;
 214                                         res = GetCustomAttributesBase (btype, attributeType);
 215                                 }
 216                         } while (inherit && btype != null);
 217
 218                         object[] array = null;
 219                         if (attributeType == null || attributeType.IsValueType)
 220                         {
 221                                 array = (object[]) Array.CreateInstance (typeof(Attribute), a.Count);
 222                         }
 223                         else
 224                         {
 225                                 array = Array.CreateInstance (attributeType, a.Count) as object[];
 226                         }
 227
 228                         // copy attributes to array
 229                         a.CopyTo (array, 0);
 230
 231                         return array;
 232                 }
 233
 234                 internal static object[] GetCustomAttributes (ICustomAttributeProvider obj, bool inherit)
 235                 {
 236                         if (obj == null)
 237                                 throw new ArgumentNullException ("obj");
 238
 239                         if (!inherit)
 240                                 return (object[]) GetCustomAttributesBase (obj, null).Clone ();
 241
 242                         return GetCustomAttributes (obj, null, inherit);
 243                 }
 244
 245 #if NET_2_0
 246                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 247                 static extern CustomAttributeData [] GetCustomAttributesDataInternal (ICustomAttributeProvider obj);
 248
 249                 internal static IList<CustomAttributeData> GetCustomAttributesData (ICustomAttributeProvider obj)
 250                 {
 251                         if (obj == null)
 252                                 throw new ArgumentNullException ("obj");
 253
 254                         CustomAttributeData [] attrs = GetCustomAttributesDataInternal (obj);
 255                         return Array.AsReadOnly<CustomAttributeData> (attrs);
 256                 }
 257 #endif
 258
 259                 internal static bool IsDefined (ICustomAttributeProvider obj, Type attributeType, bool inherit)
 260                 {
 261                         if (obj.GetType ().Assembly != typeof (int).Assembly)
 262                                 // User types might overwrite GetCustomAttributes () but not
 263                                 // IsDefined ().
 264                                 return obj.GetCustomAttributes (attributeType, inherit).Length > 0;
 265
 266                         if (IsDefinedInternal (obj, attributeType))
 267                                 return true;
 268
 269                         object[] pseudoAttrs = GetPseudoCustomAttributes (obj, attributeType);
 270                         if (pseudoAttrs != null) {
 271                                 for (int i = 0; i < pseudoAttrs.Length; ++i)
 272                                         if (attributeType.IsAssignableFrom (pseudoAttrs [i].GetType ()))
 273                                                 return true;
 274                         }
 275
 276                         ICustomAttributeProvider btype;
 277                         if (inherit && ((btype = GetBase (obj)) != null))
 278                                 return IsDefined (btype, attributeType, inherit);
 279
 280                         return false;
 281                 }
 282
 283                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
 284                 internal static extern bool IsDefinedInternal (ICustomAttributeProvider obj, Type AttributeType);
 285
 286                 // Handles Type, MonoProperty and MonoMethod.
 287                 // The runtime has also cases for MonoEvent, MonoField, Assembly and ParameterInfo,
 288                 // but for those we return null here.
 289                 static ICustomAttributeProvider GetBase (ICustomAttributeProvider obj)
 290                 {
 291                         if (obj == null)
 292                                 return null;
 293
 294                         if (obj is Type)
 295                                 return ((Type) obj).BaseType;
 296
 297                         MethodInfo method = null;
 298                         if (obj is MonoProperty)
 299                         {
 300                                 MonoProperty prop = (MonoProperty) obj;
 301                                 method = prop.GetGetMethod (true);
 302                                 if (method == null)
 303                                         method = prop.GetSetMethod (true);
 304                         }
 305                         else if (obj is MonoMethod)
 306                         {
 307                                 method = (MethodInfo) obj;
 308                         }
 309
 310                         /**
 311                          * ParameterInfo -> null
 312                          * Assembly -> null
 313                          * MonoEvent -> null
 314                          * MonoField -> null
 315                          */
 316                         if (method == null || !method.IsVirtual)
 317                                 return null;
 318
 319                         MethodInfo baseMethod = method.GetBaseDefinition ();
 320                         if (baseMethod == method)
 321                                 return null;
 322
 323                         return baseMethod;
 324                 }
 325
 326                 private static AttributeUsageAttribute RetrieveAttributeUsage (Type attributeType)
 327                 {
 328                         if (attributeType == typeof (AttributeUsageAttribute))
 329                                 /* Avoid endless recursion */
 330                                 return new AttributeUsageAttribute (AttributeTargets.Class);
 331
 332                         AttributeUsageAttribute usageAttribute = null;
 333                         object[] attribs = GetCustomAttributes (attributeType,
 334                                 MonoCustomAttrs.AttributeUsageType, false);
 335                         if (attribs.Length == 0)
 336                         {
 337                                 // if no AttributeUsage was defined on the attribute level, then
 338                                 // try to retrieve if from its base type
 339                                 if (attributeType.BaseType != null)
 340                                 {
 341                                         usageAttribute = RetrieveAttributeUsage (attributeType.BaseType);
 342
 343                                 }
 344                                 if (usageAttribute != null)
 345                                 {
 346                                         // return AttributeUsage of base class
 347                                         return usageAttribute;
 348
 349                                 }
 350                                 // return default AttributeUsageAttribute if no AttributeUsage
 351                                 // was defined on attribute, or its base class
 352                                 return DefaultAttributeUsage;
 353                         }
 354                         // check if more than one AttributeUsageAttribute has been specified
 355                         // on the type
 356                         // NOTE: compilers should prevent this, but that doesn't prevent
 357                         // anyone from using IL ofcourse
 358                         if (attribs.Length > 1)
 359                         {
 360                                 throw new FormatException ("Duplicate AttributeUsageAttribute cannot be specified on an attribute type.");
 361                         }
 362
 363                         return ((AttributeUsageAttribute) attribs[0]);
 364                 }
 365
 366                 private static readonly Type AttributeUsageType = typeof(AttributeUsageAttribute);
 367                 private static readonly AttributeUsageAttribute DefaultAttributeUsage =
 368                         new AttributeUsageAttribute (AttributeTargets.All);
 369
 370                 private class AttributeInfo
 371                 {
 372                         private AttributeUsageAttribute _usage;
 373                         private int _inheritanceLevel;
 374
 375                         public AttributeInfo (AttributeUsageAttribute usage, int inheritanceLevel)
 376                         {
 377                                 _usage = usage;
 378                                 _inheritanceLevel = inheritanceLevel;
 379                         }
 380
 381                         public AttributeUsageAttribute Usage
 382                         {
 383                                 get
 384                                 {
 385                                         return _usage;
 386                                 }
 387                         }
 388
 389                         public int InheritanceLevel
 390                         {
 391                                 get
 392                                 {
 393                                         return _inheritanceLevel;
 394                                 }
 395                         }
 396                 }
 397         }
 398 }
 399