Split get_default() into two for deferred default construction and added forwarding...

[folly.git] / folly / test / MapUtilTest.cpp

diff --git a/folly/test/MapUtilTest.cpp b/folly/test/MapUtilTest.cpp
index 1fa91df0f054d004d9743de460243ab99d143375..7ef13f718fcf757e50fc2e7a202bcbb118cabc01 100644 (file)
--- a/folly/test/MapUtilTest.cpp
+++ b/folly/test/MapUtilTest.cpp
@@ -16,9 +16,11 @@
 
 #include <folly/MapUtil.h>
 
+#include <cstddef>
 #include <map>
 #include <unordered_map>
 
+#include <folly/Traits.h>
 #include <folly/portability/GTest.h>
 
 using namespace folly;
@@ -138,3 +140,159 @@ TEST(MapUtil, get_ptr_path_mixed) {
   EXPECT_TRUE(get_ptr(cm, "a", 1, "b"));
   EXPECT_FALSE(get_ptr(cm, "b", 1, "b"));
 }
+
+namespace {
+template <typename T>
+struct element_type {
+  using type = typename std::decay<T>::type;
+};
+
+template <typename T>
+struct element_type<T()> {
+  using type = T;
+};
+
+template <typename T>
+using element_type_t = typename element_type<T>::type;
+
+template <typename T, typename = void>
+struct Compiles : std::false_type {};
+
+template <typename T>
+struct Compiles<
+    T,
+    void_t<decltype(get_ref_default(
+        std::declval<std::map<int, element_type_t<T>>>(),
+        std::declval<int>(),
+        std::declval<T>()))>> : std::true_type {};
+} // namespace
+
+TEST(MapUtil, get_default_temporary) {
+  EXPECT_TRUE(Compiles<const int&>::value);
+  EXPECT_TRUE(Compiles<int&>::value);
+  EXPECT_FALSE(Compiles<const int&&>::value);
+  EXPECT_FALSE(Compiles<int&&>::value);
+
+  EXPECT_TRUE(Compiles<const int&()>::value);
+  EXPECT_TRUE(Compiles<int&()>::value);
+  EXPECT_FALSE(Compiles<int()>::value);
+}
+
+TEST(MapUtil, get_default_path) {
+  using std::map;
+  map<int, map<int, int>> m;
+  m[4][2] = 42;
+  EXPECT_EQ(42, get_default(m, 4, 2, 42));
+  EXPECT_EQ(42, get_default(m, 1, 3, 42));
+}
+
+TEST(MapUtil, get_default_path_mixed) {
+  using std::map;
+  using std::unordered_map;
+  using std::string;
+  map<int, unordered_map<string, StringPiece>> m;
+  int key1 = 42;
+  const string key2 = "hello";
+  constexpr StringPiece value = "world";
+  constexpr StringPiece dflt = "default";
+  m[key1][key2] = value;
+  EXPECT_EQ(value, get_default(m, 42, key2, dflt));
+  EXPECT_EQ(value, get_default(m, key1, "hello", dflt));
+  EXPECT_EQ(dflt, get_default(m, 0, key2, dflt));
+  EXPECT_EQ(dflt, get_default(m, key1, "bad", "default"));
+}
+
+TEST(MapUtil, get_ref_default_path) {
+  using std::map;
+  map<int, map<int, int>> m;
+  m[4][2] = 42;
+  const int dflt = 13;
+  EXPECT_EQ(42, get_ref_default(m, 4, 2, dflt));
+  EXPECT_EQ(dflt, get_ref_default(m, 1, 3, dflt));
+}
+
+TEST(MapUtil, get_ref_default_path_mixed) {
+  using std::map;
+  using std::unordered_map;
+  using std::string;
+  map<int, unordered_map<string, StringPiece>> m;
+  int key1 = 42;
+  const string key2 = "hello";
+  constexpr StringPiece value = "world";
+  constexpr StringPiece dflt = "default";
+  m[key1][key2] = value;
+  EXPECT_EQ(value, get_ref_default(m, 42, key2, dflt));
+  EXPECT_EQ(value, get_ref_default(m, key1, "hello", dflt));
+  EXPECT_EQ(dflt, get_ref_default(m, 0, key2, dflt));
+  EXPECT_EQ(dflt, get_ref_default(m, key1, "bad", dflt));
+}
+
+namespace {
+template <typename T, typename = void>
+struct GetRefDefaultPathCompiles : std::false_type {};
+
+template <typename T>
+struct GetRefDefaultPathCompiles<
+    T,
+    void_t<decltype(get_ref_default(
+        std::declval<std::map<int, std::map<int, element_type_t<T>>>>(),
+        std::declval<int>(),
+        std::declval<int>(),
+        std::declval<T>()))>> : std::true_type {};
+} // namespace
+
+TEST(MapUtil, get_ref_default_path_temporary) {
+  EXPECT_TRUE(GetRefDefaultPathCompiles<const int&>::value);
+  EXPECT_TRUE(GetRefDefaultPathCompiles<int&>::value);
+  EXPECT_FALSE(GetRefDefaultPathCompiles<const int&&>::value);
+  EXPECT_FALSE(GetRefDefaultPathCompiles<int&&>::value);
+}
+
+namespace {
+
+class TestConstruction {
+ public:
+  TestConstruction() {
+    EXPECT_TRUE(false);
+  }
+  TestConstruction(TestConstruction&&) {
+    EXPECT_TRUE(false);
+  }
+  TestConstruction(const TestConstruction&) {
+    EXPECT_TRUE(false);
+  }
+
+  explicit TestConstruction(std::string&& string)
+      : string_{std::move(string)} {}
+  explicit TestConstruction(int&& integer) : integer_{integer} {}
+
+  TestConstruction& operator=(const TestConstruction&) = delete;
+  TestConstruction& operator=(TestConstruction&&) = delete;
+
+  int integer_{};
+  std::string string_{};
+};
+
+} // namespace
+
+TEST(MapUtil, test_get_default_deferred_construction) {
+  auto map = std::unordered_map<int, TestConstruction>{};
+  map.emplace(
+      std::piecewise_construct,
+      std::forward_as_tuple(1),
+      std::forward_as_tuple(1));
+
+  EXPECT_EQ(map.at(1).integer_, 1);
+
+  {
+    auto val = get_default(map, 0, 1);
+    EXPECT_EQ(val.integer_, 1);
+    EXPECT_EQ(val.string_, "");
+  }
+
+  {
+    auto val = get_default(map, 0, "something");
+    EXPECT_EQ(val.integer_, 0);
+    EXPECT_EQ(val.string_, "something");
+  }
+}