CXX-2096 Add BSON UDL for from_json()

src/bsoncxx/json.cpp

@@ -89,5 +89,9 @@ document::value BSONCXX_CALL from_json(stdx::string_view json) {
     return document::value{buf, length, bson_free_deleter};
 }
 
+document::value BSONCXX_CALL operator"" _bson(const char* str, size_t len) {
+    return from_json(stdx::string_view{str, len});
+}
+
 BSONCXX_INLINE_NAMESPACE_END
 }  // namespace bsoncxx

src/bsoncxx/json.hpp

@@ -57,17 +57,33 @@ BSONCXX_API std::string BSONCXX_CALL to_json(document::view view,
                                              ExtendedJsonMode mode = ExtendedJsonMode::k_legacy);
 
 ///
-/// Constructs a new document::value from the provided JSON text
+/// Constructs a new document::value from the provided JSON text.
 ///
 /// @param 'json'
-///  A string_view into a JSON document
+///  A string_view into a JSON document.
 ///
 /// @returns A document::value if conversion worked.
 ///
 /// @throws bsoncxx::exception with error details if the conversion failed.
 ///
 BSONCXX_API document::value BSONCXX_CALL from_json(stdx::string_view json);
 
+///
+/// Constructs a new document::value from the provided JSON text. This is the UDL version of
+/// from_json().
+///
+/// @param 'json'
+///  A string into a JSON document.
+///
+/// @param 'len'
+///  The length of the JSON string. This is calculated automatically upon use of the UDL.
+///
+/// @returns A document::value if conversion worked.
+///
+/// @throws bsoncxx::exception with error details if the conversion failed.
+///
+BSONCXX_API document::value BSONCXX_CALL operator"" _bson(const char* json, size_t len);
+
 BSONCXX_INLINE_NAMESPACE_END
 }  // namespace bsoncxx
 

src/bsoncxx/test/json.cpp

@@ -112,4 +112,27 @@ TEST_CASE("CXX-1246: Canonical Extended JSON") {
         output ==
         R"({ "number" : { "$numberInt" : "42" }, "bin" : { "$binary" : { "base64": "ZGVhZGJlZWY=", "subType" : "04" } } })");
 }
+
+TEST_CASE("UDL _bson works like from_json()") {
+    using namespace bsoncxx;
+
+    SECTION("_bson and from_json() return the same value") {
+        auto expected_value = from_json(k_valid_json);
+        auto actual_value = R"({ "a" : 1, "b" : 2.0 })"_bson;
+
+        REQUIRE(actual_value == expected_value);
+        REQUIRE("[1, 2, 3]"_bson == from_json("[1, 2, 3]"));
+    }
+
+    SECTION("_bson returns an empty document") {
+        REQUIRE("{}"_bson == from_json("{  }"));
+        REQUIRE("{}"_bson.view().empty());
+    }
+
+    SECTION("_bson throws an exception with invalid json") {
+        REQUIRE_THROWS_AS(R"({])"_bson, bsoncxx::exception);
+        REQUIRE_THROWS_AS(""_bson, bsoncxx::exception);
+    }
+}
+
 }  // namespace