fix issue #161 doubling comment on empty value

3 files changed, 49 insertions, 1 deletions

diff --git a/_test/test_issues.py b/_test/test_issues.py
index e73dc06..1793edb 100644
--- a/_test/test_issues.py
+++ b/_test/test_issues.py
@@ -37,3 +37,26 @@ class TestIssues:
         """)
         x = round_trip(s, block_seq_indent=4, preserve_quotes=True)
         assert x['bar'] == 32
+
+    def test_issue_161(self):
+        yaml_str = dedent("""\
+        mapping-A:
+          key-A:{}
+        mapping-B:
+        """)
+        for comment in ['', ' # no-newline', '  # some comment\n', '\n', ]:
+            s = yaml_str.format(comment)
+            res = round_trip(s)
+
+    def test_issue_161a(self):
+        yaml_str = dedent("""\
+        mapping-A:
+          key-A:{}
+        mapping-B:
+        """)
+        for comment in ['\n# between']:
+            s = yaml_str.format(comment)
+            res = round_trip(s)
+            # print(s)
+            # print('------------')
+        # assert False
diff --git a/main.py b/main.py
index ce607bf..fa9db38 100644
--- a/main.py
+++ b/main.py
@@ -639,6 +639,27 @@ class YAML(object):
             self.constructor.add_constructor(tag, f_y)
         return cls
 
+
+    def parse(self, stream):
+        # type: (StreamTextType, Any) -> Any
+        """
+        Parse a YAML stream and produce parsing events.
+        """
+        _, parser = self.get_constructor_parser(stream)
+        try:
+            while parser.check_event():
+                yield parser.get_event()
+        finally:
+            parser.dispose()
+            try:
+                self._reader.reset_reader()  # type: ignore
+            except AttributeError:
+                pass
+            try:
+                self._scanner.reset_scanner()  # type: ignore
+            except AttributeError:
+                pass
+
     # ### context manager
 
     def __enter__(self):
diff --git a/parser.py b/parser.py
index 9c6041d..0707761 100644
--- a/parser.py
+++ b/parser.py
@@ -598,7 +598,11 @@ class Parser(object):
                 self.state = self.parse_block_mapping_key
                 comment = token.comment
                 if comment is None:
-                    comment = self.scanner.peek_token().comment
+                    token = self.scanner.peek_token()
+                    comment = token.comment
+                    if comment:
+                        token._comment = [None, comment[1]]
+                        comment = [comment[0], None]
                 return self.process_empty_scalar(token.end_mark, comment=comment)
         else:
             self.state = self.parse_block_mapping_key