tag_null (#897)

src/singledocparser.cpp

@@ -90,16 +90,17 @@ void SingleDocParser::HandleNode(EventHandler& eventHandler) {
 
   const Token& token = m_scanner.peek();
 
-  if (token.type == Token::PLAIN_SCALAR && IsNullString(token.value)) {
+  // add non-specific tags
+  if (tag.empty())
+    tag = (token.type == Token::NON_PLAIN_SCALAR ? "!" : "?");
+  
+  if (token.type == Token::PLAIN_SCALAR 
+      && tag.compare("?") == 0 && IsNullString(token.value)) {
     eventHandler.OnNull(mark, anchor);
     m_scanner.pop();
     return;
   }
 
-  // add non-specific tags
-  if (tag.empty())
-    tag = (token.type == Token::NON_PLAIN_SCALAR ? "!" : "?");
-
   // now split based on what kind of node we should be
   switch (token.type) {
     case Token::PLAIN_SCALAR:

test/integration/load_node_test.cpp

@@ -269,7 +269,18 @@ TEST(NodeTest, LoadTildeAsNull) {
   Node node = Load("~");
   ASSERT_TRUE(node.IsNull());
 }
-    
+
+TEST(NodeTest, LoadNullWithStrTag) {
+  Node node = Load("!!str null");
+  EXPECT_EQ(node.Tag(), "tag:yaml.org,2002:str");
+  EXPECT_EQ(node.as<std::string>(), "null");
+}
+
+TEST(NodeTest, LoadQuotedNull) {
+  Node node = Load("\"null\"");
+  EXPECT_EQ(node.as<std::string>(), "null");
+}
+
 TEST(NodeTest, LoadTagWithParenthesis) {
     Node node = Load("!Complex(Tag) foo");
     EXPECT_EQ(node.Tag(), "!Complex(Tag)");