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Fix docstrings of visit_stmt and normalize_invisible_parens
[etc/vim.git] / black.py
index f235afe60c7aa3545a16fd96c0e8d7a9459fa72b..eb99a41b04217f3cdc0cc551be97014eee7fe62f 100644 (file)
--- a/black.py
+++ b/black.py
@@ -41,7 +41,7 @@ from blib2to3 import pygram, pytree
 from blib2to3.pgen2 import driver, token
 from blib2to3.pgen2.parse import ParseError
 
-__version__ = "18.4a4"
+__version__ = "18.4a6"
 DEFAULT_LINE_LENGTH = 88
 
 # types
@@ -553,19 +553,20 @@ COMPARATORS = {
     token.GREATEREQUAL,
 }
 MATH_OPERATORS = {
+    token.VBAR,
+    token.CIRCUMFLEX,
+    token.AMPER,
+    token.LEFTSHIFT,
+    token.RIGHTSHIFT,
     token.PLUS,
     token.MINUS,
     token.STAR,
     token.SLASH,
-    token.VBAR,
-    token.AMPER,
+    token.DOUBLESLASH,
     token.PERCENT,
-    token.CIRCUMFLEX,
+    token.AT,
     token.TILDE,
-    token.LEFTSHIFT,
-    token.RIGHTSHIFT,
     token.DOUBLESTAR,
-    token.DOUBLESLASH,
 }
 STARS = {token.STAR, token.DOUBLESTAR}
 VARARGS_PARENTS = {
@@ -599,12 +600,27 @@ TEST_DESCENDANTS = {
     syms.power,
 }
 COMPREHENSION_PRIORITY = 20
-COMMA_PRIORITY = 10
-TERNARY_PRIORITY = 7
-LOGIC_PRIORITY = 5
-STRING_PRIORITY = 4
-COMPARATOR_PRIORITY = 3
-MATH_PRIORITY = 1
+COMMA_PRIORITY = 18
+TERNARY_PRIORITY = 16
+LOGIC_PRIORITY = 14
+STRING_PRIORITY = 12
+COMPARATOR_PRIORITY = 10
+MATH_PRIORITIES = {
+    token.VBAR: 8,
+    token.CIRCUMFLEX: 7,
+    token.AMPER: 6,
+    token.LEFTSHIFT: 5,
+    token.RIGHTSHIFT: 5,
+    token.PLUS: 4,
+    token.MINUS: 4,
+    token.STAR: 3,
+    token.SLASH: 3,
+    token.DOUBLESLASH: 3,
+    token.PERCENT: 3,
+    token.AT: 3,
+    token.TILDE: 2,
+    token.DOUBLESTAR: 1,
+}
 
 
 @dataclass
@@ -743,6 +759,8 @@ class Line:
         if not has_value:
             return
 
+        if token.COLON == leaf.type and self.is_class_paren_empty:
+            del self.leaves[-2:]
         if self.leaves and not preformatted:
             # Note: at this point leaf.prefix should be empty except for
             # imports, for which we only preserve newlines.
@@ -752,7 +770,6 @@ class Line:
         if self.inside_brackets or not preformatted:
             self.bracket_tracker.mark(leaf)
             self.maybe_remove_trailing_comma(leaf)
-
         if not self.append_comment(leaf):
             self.leaves.append(leaf)
 
@@ -840,6 +857,22 @@ class Line:
             and self.leaves[0].value == "yield"
         )
 
+    @property
+    def is_class_paren_empty(self) -> bool:
+        """Is this a class with no base classes but using parentheses?
+
+        Those are unnecessary and should be removed.
+        """
+        return (
+            bool(self)
+            and len(self.leaves) == 4
+            and self.is_class
+            and self.leaves[2].type == token.LPAR
+            and self.leaves[2].value == "("
+            and self.leaves[3].type == token.RPAR
+            and self.leaves[3].value == ")"
+        )
+
     def contains_standalone_comments(self, depth_limit: int = sys.maxsize) -> bool:
         """If so, needs to be split before emitting."""
         for leaf in self.leaves:
@@ -868,9 +901,14 @@ class Line:
                 self.remove_trailing_comma()
                 return True
 
-        # For parens let's check if it's safe to remove the comma.  If the
-        # trailing one is the only one, we might mistakenly change a tuple
-        # into a different type by removing the comma.
+        # For parens let's check if it's safe to remove the comma.
+        # Imports are always safe.
+        if self.is_import:
+            self.remove_trailing_comma()
+            return True
+
+        # Otheriwsse, if the trailing one is the only one, we might mistakenly
+        # change a tuple into a different type by removing the comma.
         depth = closing.bracket_depth + 1
         commas = 0
         opening = closing.opening_bracket
@@ -1219,9 +1257,8 @@ class LineGenerator(Visitor[Line]):
         The relevant Python language `keywords` for a given statement will be
         NAME leaves within it. This methods puts those on a separate line.
 
-        `parens` holds pairs of nodes where invisible parentheses should be put.
-        Keys hold nodes after which opening parentheses should be put, values
-        hold nodes before which closing parentheses should be put.
+        `parens` holds a set of string leaf values immeditely after which
+        invisible parens should be put.
         """
         normalize_invisible_parens(node, parens_after=parens)
         for child in node.children:
@@ -1627,7 +1664,7 @@ def is_split_before_delimiter(leaf: Leaf, previous: Leaf = None) -> int:
         and leaf.parent
         and leaf.parent.type not in {syms.factor, syms.star_expr}
     ):
-        return MATH_PRIORITY
+        return MATH_PRIORITIES[leaf.type]
 
     if leaf.type in COMPARATORS:
         return COMPARATOR_PRIORITY
@@ -1808,7 +1845,8 @@ def left_hand_split(line: Line, py36: bool = False) -> Iterator[Line]:
     """Split line into many lines, starting with the first matching bracket pair.
 
     Note: this usually looks weird, only use this for function definitions.
-    Prefer RHS otherwise.
+    Prefer RHS otherwise.  This is why this function is not symmetrical with
+    :func:`right_hand_split` which also handles optional parentheses.
     """
     head = Line(depth=line.depth)
     body = Line(depth=line.depth + 1, inside_brackets=True)
@@ -1848,7 +1886,10 @@ def left_hand_split(line: Line, py36: bool = False) -> Iterator[Line]:
 def right_hand_split(
     line: Line, py36: bool = False, omit: Collection[LeafID] = ()
 ) -> Iterator[Line]:
-    """Split line into many lines, starting with the last matching bracket pair."""
+    """Split line into many lines, starting with the last matching bracket pair.
+
+    If the split was by optional parentheses, attempt splitting without them, too.
+    """
     head = Line(depth=line.depth)
     body = Line(depth=line.depth + 1, inside_brackets=True)
     tail = Line(depth=line.depth)
@@ -1887,20 +1928,25 @@ def right_hand_split(
     bracket_split_succeeded_or_raise(head, body, tail)
     assert opening_bracket and closing_bracket
     if (
+        # the opening bracket is an optional paren
         opening_bracket.type == token.LPAR
         and not opening_bracket.value
+        # the closing bracket is an optional paren
         and closing_bracket.type == token.RPAR
         and not closing_bracket.value
+        # there are no delimiters or standalone comments in the body
+        and not body.bracket_tracker.delimiters
+        and not line.contains_standalone_comments(0)
+        # and it's not an import (optional parens are the only thing we can split
+        # on in this case; attempting a split without them is a waste of time)
+        and not line.is_import
     ):
-        # These parens were optional. If there aren't any delimiters or standalone
-        # comments in the body, they were unnecessary and another split without
-        # them should be attempted.
-        if not (
-            body.bracket_tracker.delimiters or line.contains_standalone_comments(0)
-        ):
-            omit = {id(closing_bracket), *omit}
+        omit = {id(closing_bracket), *omit}
+        try:
             yield from right_hand_split(line, py36=py36, omit=omit)
             return
+        except CannotSplit:
+            pass
 
     ensure_visible(opening_bracket)
     ensure_visible(closing_bracket)
@@ -2158,6 +2204,9 @@ def normalize_string_quotes(leaf: Leaf) -> None:
 def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None:
     """Make existing optional parentheses invisible or create new ones.
 
+    `parens_after` is a set of string leaf values immeditely after which parens
+    should be put.
+
     Standardizes on visible parentheses for single-element tuples, and keeps
     existing visible parentheses for other tuples and generator expressions.
     """
@@ -2165,17 +2214,7 @@ def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None:
     for child in list(node.children):
         if check_lpar:
             if child.type == syms.atom:
-                if not (
-                    is_empty_tuple(child)
-                    or is_one_tuple(child)
-                    or max_delimiter_priority_in_atom(child) >= COMMA_PRIORITY
-                ):
-                    first = child.children[0]
-                    last = child.children[-1]
-                    if first.type == token.LPAR and last.type == token.RPAR:
-                        # make parentheses invisible
-                        first.value = ""  # type: ignore
-                        last.value = ""  # type: ignore
+                maybe_make_parens_invisible_in_atom(child)
             elif is_one_tuple(child):
                 # wrap child in visible parentheses
                 lpar = Leaf(token.LPAR, "(")
@@ -2192,6 +2231,29 @@ def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None:
         check_lpar = isinstance(child, Leaf) and child.value in parens_after
 
 
+def maybe_make_parens_invisible_in_atom(node: LN) -> bool:
+    """If it's safe, make the parens in the atom `node` invisible, recusively."""
+    if (
+        node.type != syms.atom
+        or is_empty_tuple(node)
+        or is_one_tuple(node)
+        or max_delimiter_priority_in_atom(node) >= COMMA_PRIORITY
+    ):
+        return False
+
+    first = node.children[0]
+    last = node.children[-1]
+    if first.type == token.LPAR and last.type == token.RPAR:
+        # make parentheses invisible
+        first.value = ""  # type: ignore
+        last.value = ""  # type: ignore
+        if len(node.children) > 1:
+            maybe_make_parens_invisible_in_atom(node.children[1])
+        return True
+
+    return False
+
+
 def is_empty_tuple(node: LN) -> bool:
     """Return True if `node` holds an empty tuple."""
     return (
@@ -2293,7 +2355,7 @@ def is_python36(node: Node) -> bool:
 
     Currently looking for:
     - f-strings; and
-    - trailing commas after * or ** in function signatures.
+    - trailing commas after * or ** in function signatures and calls.
     """
     for n in node.pre_order():
         if n.type == token.STRING:
@@ -2302,7 +2364,7 @@ def is_python36(node: Node) -> bool:
                 return True
 
         elif (
-            n.type == syms.typedargslist
+            n.type in {syms.typedargslist, syms.arglist}
             and n.children
             and n.children[-1].type == token.COMMA
         ):
@@ -2310,6 +2372,11 @@ def is_python36(node: Node) -> bool:
                 if ch.type in STARS:
                     return True
 
+                if ch.type == syms.argument:
+                    for argch in ch.children:
+                        if argch.type in STARS:
+                            return True
+
     return False