fix issue743: handle the empty content of flow sep/map correctly during emitting. (#921)

* fix issue743: handle the empty content of flow sep/map correctly during emitting.

* handle the empty Tag/Anchor properly.

* delete comment

src/emitter.cpp

@@ -205,6 +205,7 @@ void Emitter::EmitBeginSeq() {
 void Emitter::EmitEndSeq() {
   if (!good())
     return;
+  FlowType::value originalType = m_pState->CurGroupFlowType();
 
   if (m_pState->CurGroupChildCount() == 0)
     m_pState->ForceFlow();
@@ -213,8 +214,12 @@ void Emitter::EmitEndSeq() {
     if (m_stream.comment())
       m_stream << "\n";
     m_stream << IndentTo(m_pState->CurIndent());
-    if (m_pState->CurGroupChildCount() == 0)
+    if (originalType == FlowType::Block) {
       m_stream << "[";
+    } else {
+      if (m_pState->CurGroupChildCount() == 0 && !m_pState->HasBegunNode())
+        m_stream << "[";
+    }
     m_stream << "]";
   }
 
@@ -235,6 +240,7 @@ void Emitter::EmitBeginMap() {
 void Emitter::EmitEndMap() {
   if (!good())
     return;
+  FlowType::value originalType = m_pState->CurGroupFlowType();
 
   if (m_pState->CurGroupChildCount() == 0)
     m_pState->ForceFlow();
@@ -243,8 +249,12 @@ void Emitter::EmitEndMap() {
     if (m_stream.comment())
       m_stream << "\n";
     m_stream << IndentTo(m_pState->CurIndent());
-    if (m_pState->CurGroupChildCount() == 0)
+    if (originalType == FlowType::Block) {
       m_stream << "{";
+    } else {
+      if (m_pState->CurGroupChildCount() == 0 && !m_pState->HasBegunNode())
+        m_stream << "{";
+    }
     m_stream << "}";
   }
 

src/emitterstate.cpp

@@ -160,6 +160,13 @@ void EmitterState::EndedGroup(GroupType::value type) {
     return SetError(ErrorMsg::UNEXPECTED_END_MAP);
   }
 
+  if (m_hasTag) {
+    SetError(ErrorMsg::INVALID_TAG);
+  }
+  if (m_hasAnchor) {
+    SetError(ErrorMsg::INVALID_ANCHOR);
+  }
+
   // get rid of the current group
   {
     std::unique_ptr<Group> pFinishedGroup = std::move(m_groups.back());

test/integration/emitter_test.cpp

@@ -138,6 +138,56 @@ TEST_F(EmitterTest, EmptyFlowSeq) {
   ExpectEmit("[]");
 }
 
+TEST_F(EmitterTest, EmptyBlockSeqWithBegunContent) {
+  out << BeginSeq;
+  out << BeginSeq << Comment("comment") << EndSeq;
+  out << BeginSeq << Newline << EndSeq;
+  out << EndSeq;
+
+  ExpectEmit(R"(-
+# comment
+  []
+-
+
+  [])");
+}
+
+TEST_F(EmitterTest, EmptyBlockMapWithBegunContent) {
+  out << BeginSeq;
+  out << BeginMap << Comment("comment") << EndMap;
+  out << BeginMap << Newline << EndMap;
+  out << EndSeq;
+
+  ExpectEmit(R"(-  # comment
+  {}
+-
+  {})");
+}
+
+TEST_F(EmitterTest, EmptyFlowSeqWithBegunContent) {
+  out << Flow;
+  out << BeginSeq;
+  out << BeginSeq << Comment("comment") << EndSeq;
+  out << BeginSeq << Newline << EndSeq;
+  out << EndSeq;
+
+  ExpectEmit(R"([[  # comment
+  ], [
+  ]])");
+}
+
+TEST_F(EmitterTest, EmptyFlowMapWithBegunContent) {
+  out << Flow;
+  out << BeginSeq;
+  out << BeginMap << Comment("comment") << EndMap;
+  out << BeginMap << Newline << EndMap;
+  out << EndSeq;
+
+  ExpectEmit(R"([{  # comment
+  }, {
+  }])");
+}
+
 TEST_F(EmitterTest, NestedBlockSeq) {
   out << BeginSeq;
   out << "item 1";
@@ -1553,6 +1603,26 @@ TEST_F(EmitterErrorTest, BadLocalTag) {
   ExpectEmitError("invalid tag");
 }
 
+TEST_F(EmitterErrorTest, BadTagAndTag) {
+  out << VerbatimTag("!far") << VerbatimTag("!foo") << "bar";
+  ExpectEmitError(ErrorMsg::INVALID_TAG);
+}
+
+TEST_F(EmitterErrorTest, BadAnchorAndAnchor) {
+  out << Anchor("far") << Anchor("foo") << "bar";
+  ExpectEmitError(ErrorMsg::INVALID_ANCHOR);
+}
+
+TEST_F(EmitterErrorTest, BadEmptyAnchorOnGroup) {
+  out << BeginSeq << "bar" << Anchor("foo") << EndSeq;
+  ExpectEmitError(ErrorMsg::INVALID_ANCHOR);
+}
+
+TEST_F(EmitterErrorTest, BadEmptyTagOnGroup) {
+  out << BeginSeq << "bar" << VerbatimTag("!foo") << EndSeq;
+  ExpectEmitError(ErrorMsg::INVALID_TAG);
+}
+
 TEST_F(EmitterErrorTest, ExtraEndSeq) {
   out << BeginSeq;
   out << "Hello";