ppapi/shared_impl/id_assignment.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef PPAPI_SHARED_IMPL_ID_ASSIGNMENT_H_
   6 #define PPAPI_SHARED_IMPL_ID_ASSIGNMENT_H_
   7
   8 #include <limits>
   9
  10 #include "base/basictypes.h"
  11 #include "ppapi/shared_impl/ppapi_shared_export.h"
  12
  13 namespace ppapi {
  14
  15 enum PPIdType {
  16   PP_ID_TYPE_MODULE,
  17   PP_ID_TYPE_INSTANCE,
  18   PP_ID_TYPE_RESOURCE,
  19   PP_ID_TYPE_VAR,
  20
  21   // Not a real type, must be last.
  22   PP_ID_TYPE_COUNT
  23 };
  24
  25 PPAPI_SHARED_EXPORT extern const unsigned int kPPIdTypeBits;
  26
  27 extern const int32 kMaxPPId;
  28
  29 // The most significant bits are the type, the rest are the value.
  30 template <typename T> inline T MakeTypedId(T value, PPIdType type) {
  31   return (value << kPPIdTypeBits) | static_cast<T>(type);
  32 }
  33
  34 template <typename T> inline bool CheckIdType(T id, PPIdType type) {
  35   // Say a resource of 0 is always valid, since that means "no resource."
  36   // You shouldn't be passing 0 var, instance, or module IDs around so those
  37   // are still invalid.
  38   if (type == PP_ID_TYPE_RESOURCE && !id)
  39     return true;
  40   const T mask = (static_cast<T>(1) << kPPIdTypeBits) - 1;
  41   return (id & mask) == type;
  42 }
  43
  44 }  // namespace ppapi
  45
  46 #endif  // PPAPI_SHARED_IMPL_ID_ASSIGNMENT_H_