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// Copyright 2014 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 COMPONENTS_SESSIONS_CORE_SESSION_ID_H_
#define COMPONENTS_SESSIONS_CORE_SESSION_ID_H_
#include <stdint.h>
#include <functional>
#include <iosfwd>
#include "components/sessions/core/sessions_export.h"
// Uniquely identifies a tab or window for the duration of a session. Pass by
// value.
class SESSIONS_EXPORT SessionID {
public:
typedef int32_t id_type;
// Creates a new instance representing an ID that has never been used before
// locally (even across browser restarts).
static SessionID NewUnique();
// Special value representing a null-like, invalid ID. It's the only value
// that returns false for is_valid().
static constexpr SessionID InvalidValue() { return SessionID(-1); }
// Should be used rarely because it can lead to collisions.
static constexpr SessionID FromSerializedValue(id_type value) {
return IsValidValue(value) ? SessionID(value) : InvalidValue();
}
// Returns whether a certain underlying ID value would represent a valid
// SessionID instance. Note that zero is also considered invalid.
static constexpr bool IsValidValue(id_type value) { return value > 0; }
// All IDs are valid except InvalidValue() above.
bool is_valid() const { return IsValidValue(id_); }
// Returns the underlying id.
id_type id() const { return id_; }
struct Hasher {
inline std::size_t operator()(SessionID id) const { return id.id(); }
};
private:
explicit constexpr SessionID(id_type id) : id_(id) {}
id_type id_;
};
inline bool operator==(SessionID lhs, SessionID rhs) {
return lhs.id() == rhs.id();
}
inline bool operator!=(SessionID lhs, SessionID rhs) {
return lhs.id() != rhs.id();
}
inline bool operator<(SessionID lhs, SessionID rhs) {
return lhs.id() < rhs.id();
}
// For use in gtest-based unit tests.
SESSIONS_EXPORT std::ostream& operator<<(std::ostream& out, SessionID id);
#endif // COMPONENTS_SESSIONS_CORE_SESSION_ID_H_
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