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- // Copyright 2020 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_TYPES_TOKEN_TYPE_H_
- #define BASE_TYPES_TOKEN_TYPE_H_
- #include <type_traits>
- #include "base/check.h"
- #include "base/types/strong_alias.h"
- #include "base/unguessable_token.h"
- namespace base {
- // A specialization of StrongAlias for UnguessableToken. Unlike
- // UnguessableToken, a TokenType<...> does not default to null and does not
- // expose the concept of null tokens. If you need to indicate a null token,
- // please use absl::optional<TokenType<...>>.
- template <typename TypeMarker>
- class TokenType : public StrongAlias<TypeMarker, UnguessableToken> {
- private:
- using Super = StrongAlias<TypeMarker, UnguessableToken>;
- public:
- TokenType() : Super(UnguessableToken::Create()) {}
- explicit TokenType(const UnguessableToken& token) : Super(token) {
- // Disallow attempts to force a null UnguessableToken into a strongly-typed
- // token. Allowing in-place nullability of UnguessableToken was a design
- // mistake; do not propagate that mistake here as well.
- CHECK(!token.is_empty());
- }
- TokenType(const TokenType& token) : Super(token.value()) {}
- TokenType(TokenType&& token) noexcept : Super(token.value()) {}
- TokenType& operator=(const TokenType& token) = default;
- TokenType& operator=(TokenType&& token) noexcept = default;
- // This object allows default assignment operators for compatibility with
- // STL containers.
- // Hash functor for use in unordered containers.
- struct Hasher {
- using argument_type = TokenType;
- using result_type = size_t;
- result_type operator()(const argument_type& token) const {
- return UnguessableTokenHash()(token.value());
- }
- };
- // Mimic the UnguessableToken API for ease and familiarity of use.
- std::string ToString() const { return this->value().ToString(); }
- };
- } // namespace base
- #endif // BASE_TYPES_TOKEN_TYPE_H_
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