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/*
* Copyright 2015 Facebook, Inc.
*
* 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
*
* http://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 FOLLY_MAPUTIL_H_
#define FOLLY_MAPUTIL_H_
#include <folly/Conv.h>
#include <folly/Optional.h>
namespace folly {
/**
* Given a map and a key, return the value corresponding to the key in the map,
* or a given default value if the key doesn't exist in the map.
*/
template <class Map>
typename Map::mapped_type get_default(
const Map& map, const typename Map::key_type& key,
const typename Map::mapped_type& dflt =
typename Map::mapped_type()) {
auto pos = map.find(key);
return (pos != map.end() ? pos->second : dflt);
}
/**
* Given a map and a key, return the value corresponding to the key in the map,
* or throw an exception of the specified type.
*/
template <class E = std::out_of_range, class Map>
typename Map::mapped_type get_or_throw(
const Map& map, const typename Map::key_type& key,
const std::string& exceptionStrPrefix = std::string()) {
auto pos = map.find(key);
if (pos != map.end()) {
return pos->second;
}
throw E(folly::to<std::string>(exceptionStrPrefix, key));
}
/**
* Given a map and a key, return a Optional<V> if the key exists and None if the
* key does not exist in the map.
*/
template <class Map>
folly::Optional<typename Map::mapped_type> get_optional(
const Map& map, const typename Map::key_type& key) {
auto pos = map.find(key);
if (pos != map.end()) {
return folly::Optional<typename Map::mapped_type>(pos->second);
} else {
return folly::none;
}
}
/**
* Given a map and a key, return a reference to the value corresponding to the
* key in the map, or the given default reference if the key doesn't exist in
* the map.
*/
template <class Map>
const typename Map::mapped_type& get_ref_default(
const Map& map, const typename Map::key_type& key,
const typename Map::mapped_type& dflt) {
auto pos = map.find(key);
return (pos != map.end() ? pos->second : dflt);
}
/**
* Given a map and a key, return a pointer to the value corresponding to the
* key in the map, or nullptr if the key doesn't exist in the map.
*/
template <class Map>
const typename Map::mapped_type* get_ptr(
const Map& map, const typename Map::key_type& key) {
auto pos = map.find(key);
return (pos != map.end() ? &pos->second : nullptr);
}
/**
* Non-const overload of the above.
*/
template <class Map>
typename Map::mapped_type* get_ptr(
Map& map, const typename Map::key_type& key) {
auto pos = map.find(key);
return (pos != map.end() ? &pos->second : nullptr);
}
} // namespace folly
#endif /* FOLLY_MAPUTIL_H_ */