| // Copyright 2018 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef BASE_TOKEN_H_ |
| #define BASE_TOKEN_H_ |
| |
| #include <stdint.h> |
| |
| #include <iosfwd> |
| #include <tuple> |
| |
| #include "base/base_export.h" |
| #include "base/hash/hash.h" |
| #include "base/optional.h" |
| |
| namespace base { |
| |
| // A Token is a randomly chosen 128-bit integer. This class supports generation |
| // from a cryptographically strong random source, or constexpr construction over |
| // fixed values (e.g. to store a pre-generated constant value). Tokens are |
| // similar in spirit and purpose to UUIDs, without many of the constraints and |
| // expectations (such as byte layout and string representation) clasically |
| // associated with UUIDs. |
| class BASE_EXPORT Token { |
| public: |
| // Constructs a zero Token. |
| constexpr Token() : high_(0), low_(0) {} |
| |
| // Constructs a Token with |high| and |low| as its contents. |
| constexpr Token(uint64_t high, uint64_t low) : high_(high), low_(low) {} |
| |
| // Constructs a new Token with random |high| and |low| values taken from a |
| // cryptographically strong random source. |
| static Token CreateRandom(); |
| |
| // The high and low 64 bits of this Token. |
| uint64_t high() const { return high_; } |
| uint64_t low() const { return low_; } |
| |
| bool is_zero() const { return high_ == 0 && low_ == 0; } |
| |
| bool operator==(const Token& other) const { |
| return high_ == other.high_ && low_ == other.low_; |
| } |
| |
| bool operator!=(const Token& other) const { return !(*this == other); } |
| |
| bool operator<(const Token& other) const { |
| return std::tie(high_, low_) < std::tie(other.high_, other.low_); |
| } |
| |
| // Generates a string representation of this Token useful for e.g. logging. |
| std::string ToString() const; |
| |
| private: |
| // Note: Two uint64_t are used instead of uint8_t[16] in order to have a |
| // simpler implementation, paricularly for |ToString()|, |is_zero()|, and |
| // constexpr value construction. |
| uint64_t high_; |
| uint64_t low_; |
| }; |
| |
| // For use in std::unordered_map. |
| struct TokenHash { |
| size_t operator()(const base::Token& token) const { |
| return base::HashInts64(token.high(), token.low()); |
| } |
| }; |
| |
| class Pickle; |
| class PickleIterator; |
| |
| // For serializing and deserializing Token values. |
| BASE_EXPORT void WriteTokenToPickle(Pickle* pickle, const Token& token); |
| BASE_EXPORT Optional<Token> ReadTokenFromPickle( |
| PickleIterator* pickle_iterator); |
| |
| } // namespace base |
| |
| #endif // BASE_TOKEN_H_ |