chromium/third_party/openscreen/src/util/flat_map.h

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UTIL_FLAT_MAP_H_
#define UTIL_FLAT_MAP_H_

#include <algorithm>
#include <initializer_list>
#include <map>
#include <utility>
#include <vector>

#include "util/osp_logging.h"

namespace openscreen {

// For small numbers of elements, a vector is much more efficient than a
// map or unordered_map due to not needing hashing. FlatMap allows for
// using map-like syntax but is backed by a std::vector, combining all the
// performance of a vector with the convenience of a map.
//
// NOTE: this class allows usage of const char* as Key or Value types, but
// it is generally recommended that you use std::string, or std::string_view
// for literals. string_view is similarly efficient to a raw char* pointer,
// but gives sizing and equality operators, among other features.
template <class Key, class Value>
class FlatMap final : public std::vector<std::pair<Key, Value>> { … };

}  // namespace openscreen

#endif  // UTIL_FLAT_MAP_H_