#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 <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) : (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) {
+template <class Map, typename Key = typename Map::key_type>
+typename Map::mapped_type get_default(
+ const Map& map,
+ const Key& key,
+ const typename Map::mapped_type& dflt = typename Map::mapped_type()) {
auto pos = map.find(key);
- if (pos != map.end()) {
- return pos->second;
- } else {
- // if elision from function parameters was allowed, then we could make the
- // third parameter a value parameter and just elide that into the return
- // value, but sadly that is not allowed (yet)
- return std::forward<Value>(dflt);
- }
+ return (pos != map.end() ? pos->second : dflt);
}
/**
#include <folly/MapUtil.h>
-#include <cstddef>
#include <map>
#include <unordered_map>
std::declval<int>(),
std::declval<int>(),
std::declval<T>()))>> : std::true_type {};
-
} // namespace
TEST(MapUtil, get_ref_default_path_temporary) {
EXPECT_FALSE(GetRefDefaultPathCompiles<const int&&>::value);
EXPECT_FALSE(GetRefDefaultPathCompiles<int&&>::value);
}
-
-namespace {
-
-class TestConstruction {
- public:
- static std::size_t numberDefaultConstructs;
- TestConstruction() {
- ++numberDefaultConstructs;
- }
- TestConstruction(TestConstruction&&) = default;
- TestConstruction(const TestConstruction&) = default;
-
- TestConstruction& operator=(const TestConstruction&) = delete;
- TestConstruction& operator=(TestConstruction&&) = delete;
-};
-
-std::size_t TestConstruction::numberDefaultConstructs = 0;
-
-} // namespace
-
-TEST(MapUtil, test_get_default_deferred_construction) {
- auto map = std::unordered_map<int, TestConstruction>{};
- map.insert({1, TestConstruction{}});
-
- EXPECT_EQ(TestConstruction::numberDefaultConstructs, 1);
-
- {
- auto val = get_default(map, 1);
- EXPECT_EQ(TestConstruction::numberDefaultConstructs, 1);
- static_cast<void>(val);
- }
-
- {
- auto val = get_default(map, 1, TestConstruction{});
- EXPECT_EQ(TestConstruction::numberDefaultConstructs, 2);
- static_cast<void>(val);
- }
-}