#include <folly/Conv.h>
#include <folly/Optional.h>
+#include <folly/functional/Invoke.h>
+#include <tuple>
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()) {
+template <typename Map, typename Key>
+typename Map::mapped_type get_default(const Map& map, const Key& key) {
auto pos = map.find(key);
- return (pos != map.end() ? pos->second : dflt);
+ return (pos != map.end()) ? (pos->second) : (typename Map::mapped_type{});
+}
+template <
+ class Map,
+ typename Key = typename Map::key_type,
+ typename Value = typename Map::mapped_type,
+ typename std::enable_if<!is_invocable<Value>::value>::type* = nullptr>
+typename Map::mapped_type
+get_default(const Map& map, const Key& key, Value&& dflt) {
+ using M = typename Map::mapped_type;
+ auto pos = map.find(key);
+ return (pos != map.end()) ? (pos->second) : M(std::forward<Value>(dflt));
}
/**
*/
template <
class Map,
+ typename Key = typename Map::key_type,
typename Func,
typename = typename std::enable_if<std::is_convertible<
typename std::result_of<Func()>::type,
typename Map::mapped_type>::value>::type>
typename Map::mapped_type
-get_default(const Map& map, const typename Map::key_type& key, Func&& dflt) {
+get_default(const Map& map, const Key& key, Func&& dflt) {
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>
+template <
+ class E = std::out_of_range,
+ class Map,
+ typename Key = typename Map::key_type>
const typename Map::mapped_type& get_or_throw(
const Map& map,
- const typename Map::key_type& key,
+ const Key& key,
const std::string& exceptionStrPrefix = std::string()) {
auto pos = map.find(key);
if (pos != map.end()) {
throw E(folly::to<std::string>(exceptionStrPrefix, key));
}
-template <class E = std::out_of_range, class Map>
+template <
+ class E = std::out_of_range,
+ class Map,
+ typename Key = typename Map::key_type>
typename Map::mapped_type& get_or_throw(
Map& map,
- const typename Map::key_type& key,
+ const Key& key,
const std::string& exceptionStrPrefix = std::string()) {
auto pos = map.find(key);
if (pos != map.end()) {
* 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>
+template <class Map, typename Key = typename Map::key_type>
folly::Optional<typename Map::mapped_type> get_optional(
- const Map& map, const typename Map::key_type& key) {
+ const Map& map,
+ const Key& key) {
auto pos = map.find(key);
if (pos != map.end()) {
return folly::Optional<typename Map::mapped_type>(pos->second);
* key in the map, or the given default reference if the key doesn't exist in
* the map.
*/
-template <class Map>
+template <class Map, typename Key = typename Map::key_type>
const typename Map::mapped_type& get_ref_default(
- const Map& map, const typename Map::key_type& key,
+ const Map& map,
+ const Key& key,
const typename Map::mapped_type& dflt) {
auto pos = map.find(key);
return (pos != map.end() ? pos->second : dflt);
* The caller must ensure that the default value outlives the reference returned
* by get_ref_default().
*/
-template <class Map>
+template <class Map, typename Key = typename Map::key_type>
const typename Map::mapped_type& get_ref_default(
const Map& map,
- const typename Map::key_type& key,
+ const Key& key,
typename Map::mapped_type&& dflt) = delete;
-template <class Map>
+template <class Map, typename Key = typename Map::key_type>
const typename Map::mapped_type& get_ref_default(
const Map& map,
- const typename Map::key_type& key,
+ const Key& key,
const typename Map::mapped_type&& dflt) = delete;
/**
*/
template <
class Map,
+ typename Key = typename Map::key_type,
typename Func,
typename = typename std::enable_if<std::is_convertible<
typename std::result_of<Func()>::type,
const typename Map::mapped_type&>::value>::type,
typename = typename std::enable_if<
std::is_reference<typename std::result_of<Func()>::type>::value>::type>
-const typename Map::mapped_type& get_ref_default(
- const Map& map,
- const typename Map::key_type& key,
- Func&& dflt) {
+const typename Map::mapped_type&
+get_ref_default(const Map& map, const Key& key, Func&& 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) {
+template <class Map, typename Key = typename Map::key_type>
+const typename Map::mapped_type* get_ptr(const Map& map, const Key& 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) {
+template <class Map, typename Key = typename Map::key_type>
+typename Map::mapped_type* get_ptr(Map& map, const Key& key) {
auto pos = map.find(key);
return (pos != map.end() ? &pos->second : nullptr);
}
+// TODO: Remove the return type computations when clang 3.5 and gcc 5.1 are
+// the minimum supported versions.
namespace detail {
template <
class T,
struct NestedMapType<T, 1> {
using type = typename T::mapped_type;
};
+
+template <typename... KeysDefault>
+struct DefaultType;
+
+template <typename Default>
+struct DefaultType<Default> {
+ using type = Default;
+};
+
+template <typename Key, typename... KeysDefault>
+struct DefaultType<Key, KeysDefault...> {
+ using type = typename DefaultType<KeysDefault...>::type;
+};
+
+template <class... KeysDefault>
+auto extract_default(const KeysDefault&... keysDefault) ->
+ typename DefaultType<KeysDefault...>::type const& {
+ return std::get<sizeof...(KeysDefault)-1>(std::tie(keysDefault...));
}
+} // namespace detail
/**
* Given a map of maps and a path of keys, return a pointer to the nested value,
return pos != map.end() ? get_ptr(pos->second, key2, keys...) : nullptr;
}
-} // namespace folly
+/**
+ * Given a map and a path of keys, return the value corresponding to the nested
+ * value, or a given default value if the path doesn't exist in the map.
+ * The default value is the last parameter, and is copied when returned.
+ */
+template <
+ class Map,
+ class Key1,
+ class Key2,
+ class... KeysDefault,
+ typename = typename std::enable_if<sizeof...(KeysDefault) != 0>::type>
+auto get_default(
+ const Map& map,
+ const Key1& key1,
+ const Key2& key2,
+ const KeysDefault&... keysDefault) ->
+ typename detail::NestedMapType<Map, 1 + sizeof...(KeysDefault)>::type {
+ if (const auto* ptr = get_ptr(map, key1)) {
+ return get_default(*ptr, key2, keysDefault...);
+ }
+ return detail::extract_default(keysDefault...);
+}
+
+/**
+ * Given a map and a path of keys, return a reference to the value corresponding
+ * to the nested value, or the given default reference if the path doesn't exist
+ * in the map.
+ * The default value is the last parameter, and must be a lvalue reference.
+ */
+template <
+ class Map,
+ class Key1,
+ class Key2,
+ class... KeysDefault,
+ typename = typename std::enable_if<sizeof...(KeysDefault) != 0>::type,
+ typename = typename std::enable_if<std::is_lvalue_reference<
+ typename detail::DefaultType<KeysDefault...>::type>::value>::type>
+auto get_ref_default(
+ const Map& map,
+ const Key1& key1,
+ const Key2& key2,
+ KeysDefault&&... keysDefault) ->
+ typename detail::NestedMapType<Map, 1 + sizeof...(KeysDefault)>::type
+ const& {
+ if (const auto* ptr = get_ptr(map, key1)) {
+ return get_ref_default(*ptr, key2, keysDefault...);
+ }
+ return detail::extract_default(keysDefault...);
+}
+} // namespace folly
projects / folly.git / blobdiff