The fast parser splitting now also checks for parentheses levels, because without that, sometimes we split in very strange positions, while ignoring others.

jedi/parser/fast.py

@@ -278,6 +278,7 @@ class FastParser(use_metaclass(CachedFastParser)):
         # Use -1, because that indent is always smaller than any other.
         indent_list = [-1, 0]
         new_indent = False
+        parentheses_level = 0
         flow_indent = None
         # All things within flows are simply being ignored.
         for i, l in enumerate(self._lines):
@@ -299,8 +300,7 @@ class FastParser(use_metaclass(CachedFastParser)):
                 # This automatically resets the flow_indent if there was a
                 # dedent or a flow just on one line (with one simple_stmt).
                 new_indent = False
-                if flow_indent is None:
+                if flow_indent is None and current_lines and not parentheses_level:
-                    if current_lines:
                     yield gen_part()
                 flow_indent = None
 
@@ -310,18 +310,23 @@ class FastParser(use_metaclass(CachedFastParser)):
                 if m:
                     # Strip whitespace and colon from flows as a check.
                     if m.group(1).strip(' \t\r\n:') in FLOWS:
+                        if not parentheses_level:
                             flow_indent = indent
                     else:
                         if not is_decorator and not just_newlines(current_lines):
                             yield gen_part()
                     is_decorator = '@' == m.group(1)
                     if not is_decorator:
+                        parentheses_level = 0
                         # The new indent needs to be higher
                         indent_list.append(indent + 1)
                         new_indent = True
                 elif is_decorator:
                     is_decorator = False
 
+            parentheses_level += (l.count('(') + l.count('[') + l.count('{')
+                                  - l.count(')') - l.count(']') - l.count('}'))
+
             current_lines.append(l)
         if current_lines:
             yield gen_part()

test/test_parser/test_fast_parser.py

@@ -334,7 +334,39 @@ def test_open_parentheses():
     # however that would require to also break properly at flow level. That is
     # not possible because of ternary statements and would lead to strange
     # behavior without much more knowledge. So we just keep it this way.
-    assert p.number_parsers_used == 1
+    assert p.number_parsers_used == 2
+
+
+def test_strange_parentheses():
+    src = dedent("""
+    class X():
+        a = (1
+    if 1 else 2)
+        def x():
+            pass
+    """)
+    check_fp(src, 2)
+
+
+def test_backslash():
+    src = dedent("""\
+    a = 1\
+        if 1 else 2
+    def x():
+        pass
+    """)
+    check_fp(src, 2)
+
+    src = dedent("""\
+    if 2:
+        a = 1\
+    if 1 else 2
+        def y():
+            pass
+    """)
+    # The dangling if leads to not splitting where we theoretically could
+    # split.
+    check_fp(src, 1)
 
 
 def test_incomplete_function():