chromium/third_party/abseil-cpp/absl/container/internal/common.h

// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef ABSL_CONTAINER_INTERNAL_COMMON_H_
#define ABSL_CONTAINER_INTERNAL_COMMON_H_

#include <cassert>
#include <type_traits>

#include "absl/meta/type_traits.h"
#include "absl/types/optional.h"

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace container_internal {

template <class, class = void>
struct IsTransparent : std::false_type { … };
IsTransparent<T, absl::void_t<typename T::is_transparent>>;

template <bool is_transparent>
struct KeyArg { … };

template <>
struct KeyArg<false> { … };

// The node_handle concept from C++17.
// We specialize node_handle for sets and maps. node_handle_base holds the
// common API of both.
template <typename PolicyTraits, typename Alloc>
class node_handle_base { … };

// For sets.
template <typename Policy, typename PolicyTraits, typename Alloc,
          typename = void>
class node_handle : public node_handle_base<PolicyTraits, Alloc> { … };

// For maps.
node_handle<Policy, PolicyTraits, Alloc, absl::void_t<typename Policy::mapped_type>>;

// Provide access to non-public node-handle functions.
struct CommonAccess { … };

// Implement the insert_return_type<> concept of C++17.
template <class Iterator, class NodeType>
struct InsertReturnType { … };

}  // namespace container_internal
ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_CONTAINER_INTERNAL_COMMON_H_