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| 1 // Copyright 2014 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 MOJO_EDK_SYSTEM_UNIQUE_IDENTIFIER_H_ | |
| 6 #define MOJO_EDK_SYSTEM_UNIQUE_IDENTIFIER_H_ | |
| 7 | |
| 8 #include <stdint.h> | |
| 9 #include <string.h> | |
| 10 | |
| 11 #include <iosfwd> | |
| 12 | |
| 13 #include "base/compiler_specific.h" | |
| 14 #include "base/containers/hash_tables.h" | |
| 15 #include "mojo/edk/system/system_impl_export.h" | |
| 16 | |
| 17 namespace mojo { | |
| 18 namespace system { | |
| 19 | |
| 20 class UniqueIdentifier; | |
| 21 | |
| 22 } // namespace system | |
| 23 } // namespace mojo | |
| 24 | |
| 25 namespace BASE_HASH_NAMESPACE { | |
| 26 | |
| 27 // Declare this before |UniqueIdentifier|, so that it can be friended. | |
| 28 template <> | |
| 29 struct hash<mojo::system::UniqueIdentifier>; | |
| 30 | |
| 31 } // BASE_HASH_NAMESPACE | |
| 32 | |
| 33 namespace mojo { | |
| 34 namespace system { | |
| 35 | |
| 36 // Declare this before |UniqueIdentifier|, so that it can be friended. | |
| 37 MOJO_SYSTEM_IMPL_EXPORT std::ostream& operator<<( | |
| 38 std::ostream& out, | |
| 39 const UniqueIdentifier& unique_identifier); | |
| 40 | |
| 41 // |UniqueIdentifier| is a POD class whose value is used to uniquely identify | |
| 42 // things. | |
| 43 class MOJO_SYSTEM_IMPL_EXPORT UniqueIdentifier { | |
| 44 public: | |
| 45 // This generates a new identifier. Uniqueness is "guaranteed" (i.e., | |
| 46 // probabilistically) for identifiers. | |
| 47 static UniqueIdentifier Generate(); | |
| 48 | |
| 49 bool operator==(const UniqueIdentifier& other) const { | |
| 50 return memcmp(data_, other.data_, sizeof(data_)) == 0; | |
| 51 } | |
| 52 bool operator!=(const UniqueIdentifier& other) const { | |
| 53 return !operator==(other); | |
| 54 } | |
| 55 bool operator<(const UniqueIdentifier& other) const { | |
| 56 return memcmp(data_, other.data_, sizeof(data_)) < 0; | |
| 57 } | |
| 58 | |
| 59 private: | |
| 60 friend BASE_HASH_NAMESPACE::hash<mojo::system::UniqueIdentifier>; | |
| 61 friend std::ostream& operator<<(std::ostream&, const UniqueIdentifier&); | |
| 62 | |
| 63 explicit UniqueIdentifier() {} | |
| 64 | |
| 65 char data_[16]; | |
| 66 | |
| 67 // Copying and assignment allowed. | |
| 68 }; | |
| 69 static_assert(sizeof(UniqueIdentifier) == 16, | |
| 70 "UniqueIdentifier has wrong size."); | |
| 71 // We want to be able to take any buffer and cast it to a |UniqueIdentifier|. | |
| 72 static_assert(ALIGNOF(UniqueIdentifier) == 1, | |
| 73 "UniqueIdentifier requires nontrivial alignment."); | |
| 74 | |
| 75 } // namespace system | |
| 76 } // namespace mojo | |
| 77 | |
| 78 namespace BASE_HASH_NAMESPACE { | |
| 79 | |
| 80 template <> | |
| 81 struct hash<mojo::system::UniqueIdentifier> { | |
| 82 size_t operator()(mojo::system::UniqueIdentifier unique_identifier) const { | |
| 83 return base::HashInts64( | |
| 84 *reinterpret_cast<uint64_t*>(unique_identifier.data_), | |
| 85 *reinterpret_cast<uint64_t*>(unique_identifier.data_ + | |
| 86 sizeof(uint64_t))); | |
| 87 } | |
| 88 }; | |
| 89 | |
| 90 } // BASE_HASH_NAMESPACE | |
| 91 | |
| 92 #endif // MOJO_EDK_SYSTEM_UNIQUE_IDENTIFIER_H_ | |
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