Encompass the dictionary value in pseudo parens

If a dictionary's value has a comment before it, then we want to include the
value within the pseudo parens. Otherwise only the comment is seen as being
part of the dictionary's value.

Author: bwendling

CHANGELOG

@@ -5,6 +5,9 @@
 ## [0.13.3] UNRELEASED
 ### Fixed
 - "not in" and "is not" should be subtyped as binary operators.
+- A non-Node dictionary value may have a comment before it. In those cases, we
+  want to avoid encompassing only the comment in pseudo parens. So we include
+  the actual value as well.
 
 ## [0.13.2] 2016-10-22
 ### Fixed

yapf/yapflib/comment_splicer.py

@@ -176,16 +176,17 @@ def _VisitNodeRec(node):
                 if comment_lineno == prev_leaf[0].lineno:
                   comment_lines = comment_prefix.splitlines()
                   value = comment_lines[0].lstrip()
-                  comment_column = prev_leaf[0].column + len(prev_leaf[0].value)
-                  comment_column += (
-                      len(comment_lines[0]) - len(comment_lines[0].lstrip()))
-                  comment_leaf = pytree.Leaf(
-                      type=token.COMMENT,
-                      value=value.rstrip('\n'),
-                      context=('', (comment_lineno, comment_column)))
-                  pytree_utils.InsertNodesAfter([comment_leaf], prev_leaf[0])
-                  comment_prefix = '\n'.join(comment_lines[1:])
-                  comment_lineno += 1
+                  if value.rstrip('\n'):
+                    comment_column = prev_leaf[0].column + len(prev_leaf[0].value)
+                    comment_column += (
+                        len(comment_lines[0]) - len(comment_lines[0].lstrip()))
+                    comment_leaf = pytree.Leaf(
+                        type=token.COMMENT,
+                        value=value.rstrip('\n'),
+                        context=('', (comment_lineno, comment_column)))
+                    pytree_utils.InsertNodesAfter([comment_leaf], prev_leaf[0])
+                    comment_prefix = '\n'.join(comment_lines[1:])
+                    comment_lineno += 1
 
                 rindex = (0 if '\n' not in comment_prefix.rstrip() else
                           comment_prefix.rstrip().rindex('\n') + 1)

yapf/yapflib/subtype_assigner.py

@@ -347,6 +347,18 @@ def _InsertPseudoParentheses(node):
   first = _GetFirstLeafNode(node)
   last = _GetLastLeafNode(node)
 
+  if first == last and first.type == token.COMMENT:
+    # A comment was inserted before the value, which is a pytree.Leaf.
+    # Encompass the dictionary's value into an ATOM node.
+    last = first.next_sibling
+    new_node = pytree.Node(syms.atom, [first.clone(), last.clone()])
+    node.replace(new_node)
+    node = new_node
+    last.remove()
+
+    first = _GetFirstLeafNode(node)
+    last = _GetLastLeafNode(node)
+
   lparen = pytree.Leaf(
       token.LPAR, u'(', context=('', (first.get_lineno(), first.column - 1)))
   last_lineno = last.get_lineno()

yapftests/reformatter_buganizer_test.py

@@ -28,6 +28,23 @@ class BuganizerFixes(yapf_test_helper.YAPFTest):
   def setUpClass(cls):
     style.SetGlobalStyle(style.CreateChromiumStyle())
 
+  def testB32737279(self):
+    unformatted_code = textwrap.dedent("""\
+        here_is_a_dict = {
+            'key': 
+            # Comment.
+            'value'
+        }
+        """)
+    expected_formatted_code = textwrap.dedent("""\
+        here_is_a_dict = {
+            'key':  # Comment.
+                'value'
+        }
+        """)
+    uwlines = yapf_test_helper.ParseAndUnwrap(unformatted_code)
+    self.assertCodeEqual(expected_formatted_code, reformatter.Reformat(uwlines))
+
   def testB32570937(self):
     code = textwrap.dedent("""\
       def _():