Repo created

TMessagesProj/jni/voip/webrtc/base/token.h

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+// 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_