2 * Copyright 2016 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
19 #include <folly/Conv.h>
20 #include <folly/Optional.h>
25 * Given a map and a key, return the value corresponding to the key in the map,
26 * or a given default value if the key doesn't exist in the map.
29 typename Map::mapped_type get_default(
30 const Map& map, const typename Map::key_type& key,
31 const typename Map::mapped_type& dflt =
32 typename Map::mapped_type()) {
33 auto pos = map.find(key);
34 return (pos != map.end() ? pos->second : dflt);
38 * Given a map and a key, return the value corresponding to the key in the map,
39 * or throw an exception of the specified type.
41 template <class E = std::out_of_range, class Map>
42 typename Map::mapped_type get_or_throw(
43 const Map& map, const typename Map::key_type& key,
44 const std::string& exceptionStrPrefix = std::string()) {
45 auto pos = map.find(key);
46 if (pos != map.end()) {
49 throw E(folly::to<std::string>(exceptionStrPrefix, key));
53 * Given a map and a key, return a Optional<V> if the key exists and None if the
54 * key does not exist in the map.
57 folly::Optional<typename Map::mapped_type> get_optional(
58 const Map& map, const typename Map::key_type& key) {
59 auto pos = map.find(key);
60 if (pos != map.end()) {
61 return folly::Optional<typename Map::mapped_type>(pos->second);
68 * Given a map and a key, return a reference to the value corresponding to the
69 * key in the map, or the given default reference if the key doesn't exist in
73 const typename Map::mapped_type& get_ref_default(
74 const Map& map, const typename Map::key_type& key,
75 const typename Map::mapped_type& dflt) {
76 auto pos = map.find(key);
77 return (pos != map.end() ? pos->second : dflt);
81 * Given a map and a key, return a pointer to the value corresponding to the
82 * key in the map, or nullptr if the key doesn't exist in the map.
85 const typename Map::mapped_type* get_ptr(
86 const Map& map, const typename Map::key_type& key) {
87 auto pos = map.find(key);
88 return (pos != map.end() ? &pos->second : nullptr);
92 * Non-const overload of the above.
95 typename Map::mapped_type* get_ptr(
96 Map& map, const typename Map::key_type& key) {
97 auto pos = map.find(key);
98 return (pos != map.end() ? &pos->second : nullptr);