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