Add a new knob to allow logical operators to split

This comes from the issue
google#844
where logical operators are bin-packed if the line is too long instead
of wrapping nicely one to each line

yapf/yapflib/format_decision_state.py

@@ -544,6 +544,37 @@ def SurroundedByParens(token):
         if not self._FitsOnLine(previous, previous.matching_bracket):
           return True
 
+    ###########################################################################
+    # Logical Operator Splitting
+    if style.Get('SPLIT_ALL_LOGICAL_OPERATORS_IF_ANY_SPLIT'):
+      split_before = style.Get("SPLIT_BEFORE_LOGICAL_OPERATOR")
+      check_token = current if split_before else current.previous_token
+      if (check_token and check_token.name == "NAME" and check_token.value in logical_line._LOGICAL_OPERATORS):
+        opening = _GetOpeningBracket(check_token)
+        if opening:
+          ending = opening.matching_bracket
+          length = ending.total_length - opening.total_length
+          length += self.stack[-1].indent
+          # If we're keeping it on a single line, but the next token is also
+          # a logical operator then we have to consider that as part of the
+          # length because we might wrap after it
+          next_token = ending.next_token
+          prev_token = opening.previous_token
+          if split_before:
+             if prev_token:
+               clause_start = _PrevLogicalClause(prev_token)
+               length += opening.total_length - clause_start.total_length
+          else:
+            if next_token:
+              clause_end = _NextLogicalClause(next_token)
+              length += clause_end.total_length - ending.total_length
+        else:
+          end_token = _LastTokenInLine(check_token)
+          length = end_token.total_length + self.stack[-1].indent
+
+        if length >= self.column_limit:
+          return True
+
     ###########################################################################
     # Original Formatting Splitting
     # These checks rely upon the original formatting. This is in order to
@@ -1159,6 +1190,26 @@ def _LastTokenInLine(current):
   return current
 
 
+def _NextLogicalClause(token):
+  """ Get the start of the next logical clause or the last token in the line"""
+  while token:
+    if token in logical_line._LOGICAL_OPERATORS:
+      return token
+    if not token.next_token:
+      return token
+    token = token.next_token
+
+
+def _PrevLogicalClause(token):
+  """ Get the start of the previous logical clause or the first token"""
+  while token:
+    if token.value in logical_line._LOGICAL_OPERATORS:
+      return token
+    if not token.previous_token:
+      return token
+    token = token.previous_token
+
+
 def _IsFunctionDefinition(current):
   prev = current.previous_token
   return current.value == '(' and prev and subtypes.FUNC_DEF in prev.subtypes

yapf/yapflib/logical_line.py

@@ -610,21 +610,40 @@ def _SplitPenalty(prev_token, cur_token):
   if pval == 'not':
     return split_penalty.UNBREAKABLE
 
-  if cur_token.node_split_penalty > 0:
-    return cur_token.node_split_penalty
-
-  if style.Get('SPLIT_BEFORE_LOGICAL_OPERATOR'):
-    # Prefer to split before 'and' and 'or'.
-    if pval in _LOGICAL_OPERATORS:
-      return style.Get('SPLIT_PENALTY_LOGICAL_OPERATOR')
-    if cval in _LOGICAL_OPERATORS:
-      return 0
-  else:
-    # Prefer to split after 'and' and 'or'.
-    if pval in _LOGICAL_OPERATORS:
-      return 0
-    if cval in _LOGICAL_OPERATORS:
-      return style.Get('SPLIT_PENALTY_LOGICAL_OPERATOR')
+  node_split_penalty = cur_token.node_split_penalty
+
+  logical_splitting = style.Get('SPLIT_ALL_LOGICAL_OPERATORS_IF_ANY_SPLIT')
+
+  if logical_splitting:
+    if style.Get('SPLIT_BEFORE_LOGICAL_OPERATOR'):
+        # Prefer to split before 'and' and 'or'.
+        if pval in _LOGICAL_OPERATORS:
+          return max(node_split_penalty, style.Get('SPLIT_PENALTY_LOGICAL_OPERATOR'))
+        if cval in _LOGICAL_OPERATORS:
+          return max(node_split_penalty, 0)
+    else:
+      # Prefer to split after 'and' and 'or'.
+      if pval in _LOGICAL_OPERATORS:
+        return max(node_split_penalty, 0)
+      if cval in _LOGICAL_OPERATORS:
+        return max(node_split_penalty, style.Get('SPLIT_PENALTY_LOGICAL_OPERATOR'))
+
+  if node_split_penalty > 0:
+    return node_split_penalty
+
+  if not logical_splitting:
+    if style.Get('SPLIT_BEFORE_LOGICAL_OPERATOR'):
+      # Prefer to split before 'and' and 'or'.
+      if pval in _LOGICAL_OPERATORS:
+        return style.Get('SPLIT_PENALTY_LOGICAL_OPERATOR')
+      if cval in _LOGICAL_OPERATORS:
+        return 0
+    else:
+      # Prefer to split after 'and' and 'or'.
+      if pval in _LOGICAL_OPERATORS:
+        return 0
+      if cval in _LOGICAL_OPERATORS:
+        return style.Get('SPLIT_PENALTY_LOGICAL_OPERATOR')
 
   if style.Get('SPLIT_BEFORE_BITWISE_OPERATOR'):
     # Prefer to split before '&', '|', and '^'.

yapf/yapflib/style.py

@@ -339,6 +339,12 @@ def method():
     SPLIT_ALL_COMMA_SEPARATED_VALUES=textwrap.dedent("""\
       Split before arguments.
     """),
+    SPLIT_ALL_LOGICAL_OPERATORS_IF_ANY_SPLIT=textwrap.dedent("""\
+      If a line that contains logical operators needs to be split, split on all
+      the logical operators in that line. This will treat logical operators
+      in sub-clauses defined by parentheses as a discrete element that will
+      ignore wrapping unless the entire clause is longer than the column width.
+    """),
     SPLIT_ALL_TOP_LEVEL_COMMA_SEPARATED_VALUES=textwrap.dedent("""\
       Split before arguments, but do not split all subexpressions recursively
       (unless needed).
@@ -497,6 +503,7 @@ def CreatePEP8Style():
       SPACES_AROUND_TUPLE_DELIMITERS=False,
       SPACES_BEFORE_COMMENT=2,
       SPLIT_ALL_COMMA_SEPARATED_VALUES=False,
+      SPLIT_ALL_LOGICAL_OPERATORS_IF_ANY_SPLIT=False,
       SPLIT_ALL_TOP_LEVEL_COMMA_SEPARATED_VALUES=False,
       SPLIT_ARGUMENTS_WHEN_COMMA_TERMINATED=False,
       SPLIT_BEFORE_ARITHMETIC_OPERATOR=False,
@@ -685,6 +692,7 @@ def _IntOrIntListConverter(s):
     SPACES_AROUND_TUPLE_DELIMITERS=_BoolConverter,
     SPACES_BEFORE_COMMENT=_IntOrIntListConverter,
     SPLIT_ALL_COMMA_SEPARATED_VALUES=_BoolConverter,
+    SPLIT_ALL_LOGICAL_OPERATORS_IF_ANY_SPLIT=_BoolConverter,
     SPLIT_ALL_TOP_LEVEL_COMMA_SEPARATED_VALUES=_BoolConverter,
     SPLIT_ARGUMENTS_WHEN_COMMA_TERMINATED=_BoolConverter,
     SPLIT_BEFORE_ARITHMETIC_OPERATOR=_BoolConverter,