Create a new contains() method

Summary: Right now, there exists a `count()` method, which seems to be doing what a `contains()` method is supposed to be doing. The name `contains()` seems more appropriate.

Reviewed By: ilvokhin

Differential Revision: D78802461

fbshipit-source-id: a323266303aff51d28b8c02f7f6a2063ff0c0ad9

Author: Akheel Kariat

folly/json/dynamic-inl.h

@@ -829,6 +829,16 @@ inline std::size_t dynamic::count(StringPiece key) const {
   return find(key) != items().end() ? 1u : 0u;
 }
 
+template <typename K>
+dynamic::IfIsNonStringDynamicConvertible<K, bool> dynamic::contains(
+    K&& key) const {
+  return count(key);
+}
+
+inline bool dynamic::contains(StringPiece key) const {
+  return count(key);
+}
+
 template <class K, class V>
 inline dynamic::IfNotIterator<K, void> dynamic::insert(K&& key, V&& val) {
   auto& obj = get<ObjectImpl>();

folly/json/dynamic.h

@@ -650,6 +650,18 @@ struct dynamic {
   IfIsNonStringDynamicConvertible<K, std::size_t> count(K&&) const;
   std::size_t count(StringPiece) const;
 
+  /**
+   * Check if key exists.
+   *
+   * If this is an object, returns whether it contains a field with
+   * the given name.  Otherwise throws TypeError.
+   *
+   * @methodset Object
+   */
+  template <typename K>
+  IfIsNonStringDynamicConvertible<K, bool> contains(K&&) const;
+  bool contains(StringPiece) const;
+
  private:
   dynamic const& atImpl(dynamic const&) const&;
 

folly/json/test/DynamicTest.cpp

@@ -414,6 +414,26 @@ TEST(Dynamic, ObjectHeterogeneousAccess) {
   EXPECT_EQ(obj.count(StringPiece{b}), 0);
   EXPECT_EQ(obj.count(StaticStrings::kBar), 0);
 
+  // contains()
+  EXPECT_TRUE(obj.contains(empty));
+  EXPECT_TRUE(obj.contains(nullptr));
+  EXPECT_TRUE(obj.contains(foo));
+
+  EXPECT_TRUE(obj.contains(a));
+  EXPECT_TRUE(obj.contains(StaticStrings::kA));
+  EXPECT_TRUE(obj.contains("a"));
+
+  EXPECT_TRUE(obj.contains(sp));
+  EXPECT_TRUE(obj.contains(StringPiece{"a"}));
+  EXPECT_TRUE(obj.contains(StaticStrings::kFoo));
+
+  EXPECT_TRUE(obj.contains(std::string{"a"}));
+  EXPECT_TRUE(obj.contains(str));
+
+  EXPECT_FALSE(obj.contains(b));
+  EXPECT_FALSE(obj.contains(StringPiece{b}));
+  EXPECT_FALSE(obj.contains(StaticStrings::kBar));
+
   // operator[]
   EXPECT_EQ(obj[empty], 456);
   EXPECT_EQ(obj[nullptr], 456);