Elaborate on Python support policy (#2819)

[etc/vim.git] / src / black / linegen.py

diff --git a/src/black/linegen.py b/src/black/linegen.py
index fafaf1032ca55e002d49a5c3b7a8789f57f522e4..b572ed0b52fdbe6d546365ffbce2876466b568d0 100644 (file)
--- a/src/black/linegen.py
+++ b/src/black/linegen.py
@@ -5,12 +5,11 @@ from functools import partial, wraps
 import sys
 from typing import Collection, Iterator, List, Optional, Set, Union
 
 import sys
 from typing import Collection, Iterator, List, Optional, Set, Union
 

-from dataclasses import dataclass, field
-

 from black.nodes import WHITESPACE, RARROW, STATEMENT, STANDALONE_COMMENT
 from black.nodes import ASSIGNMENTS, OPENING_BRACKETS, CLOSING_BRACKETS
 from black.nodes import Visitor, syms, first_child_is_arith, ensure_visible
 from black.nodes import is_docstring, is_empty_tuple, is_one_tuple, is_one_tuple_between
 from black.nodes import WHITESPACE, RARROW, STATEMENT, STANDALONE_COMMENT
 from black.nodes import ASSIGNMENTS, OPENING_BRACKETS, CLOSING_BRACKETS
 from black.nodes import Visitor, syms, first_child_is_arith, ensure_visible
 from black.nodes import is_docstring, is_empty_tuple, is_one_tuple, is_one_tuple_between

+from black.nodes import is_name_token, is_lpar_token, is_rpar_token

 from black.nodes import is_walrus_assignment, is_yield, is_vararg, is_multiline_string
 from black.nodes import is_stub_suite, is_stub_body, is_atom_with_invisible_parens
 from black.nodes import wrap_in_parentheses
 from black.nodes import is_walrus_assignment, is_yield, is_vararg, is_multiline_string
 from black.nodes import is_stub_suite, is_stub_body, is_atom_with_invisible_parens
 from black.nodes import wrap_in_parentheses


@@ -22,10 +21,9 @@ from black.comments import generate_comments, list_comments, FMT_OFF
 from black.numerics import normalize_numeric_literal
 from black.strings import get_string_prefix, fix_docstring
 from black.strings import normalize_string_prefix, normalize_string_quotes
 from black.numerics import normalize_numeric_literal
 from black.strings import get_string_prefix, fix_docstring
 from black.strings import normalize_string_prefix, normalize_string_quotes

-from black.trans import Transformer, CannotTransform, StringMerger
-from black.trans import StringSplitter, StringParenWrapper, StringParenStripper
-from black.mode import Mode
-from black.mode import Feature
+from black.trans import Transformer, CannotTransform, StringMerger, StringSplitter
+from black.trans import StringParenWrapper, StringParenStripper, hug_power_op
+from black.mode import Mode, Feature, Preview

 
 from blib2to3.pytree import Node, Leaf
 from blib2to3.pgen2 import token
 
 from blib2to3.pytree import Node, Leaf
 from blib2to3.pgen2 import token


@@ -40,7 +38,8 @@ class CannotSplit(CannotTransform):
     """A readable split that fits the allotted line length is impossible."""
 
 
     """A readable split that fits the allotted line length is impossible."""
 
 

-@dataclass
+# This isn't a dataclass because @dataclass + Generic breaks mypyc.
+# See also https://github.com/mypyc/mypyc/issues/827.

 class LineGenerator(Visitor[Line]):
     """Generates reformatted Line objects.  Empty lines are not emitted.
 
 class LineGenerator(Visitor[Line]):
     """Generates reformatted Line objects.  Empty lines are not emitted.
 


@@ -48,9 +47,10 @@ class LineGenerator(Visitor[Line]):
     in ways that will no longer stringify to valid Python code on the tree.
     """
 
     in ways that will no longer stringify to valid Python code on the tree.
     """
 

-    mode: Mode
-    remove_u_prefix: bool = False
-    current_line: Line = field(init=False)
+    def __init__(self, mode: Mode) -> None:
+        self.mode = mode
+        self.current_line: Line
+        self.__post_init__()

 
     def line(self, indent: int = 0) -> Iterator[Line]:
         """Generate a line.
 
     def line(self, indent: int = 0) -> Iterator[Line]:
         """Generate a line.


@@ -90,9 +90,7 @@ class LineGenerator(Visitor[Line]):
 
             normalize_prefix(node, inside_brackets=any_open_brackets)
             if self.mode.string_normalization and node.type == token.STRING:
 
             normalize_prefix(node, inside_brackets=any_open_brackets)
             if self.mode.string_normalization and node.type == token.STRING:

-                node.value = normalize_string_prefix(
-                    node.value, remove_u_prefix=self.remove_u_prefix
-                )
+                node.value = normalize_string_prefix(node.value)

                 node.value = normalize_string_quotes(node.value)
             if node.type == token.NUMBER:
                 normalize_numeric_literal(node)
                 node.value = normalize_string_quotes(node.value)
             if node.type == token.NUMBER:
                 normalize_numeric_literal(node)


@@ -126,7 +124,7 @@ class LineGenerator(Visitor[Line]):
         """Visit a statement.
 
         This implementation is shared for `if`, `while`, `for`, `try`, `except`,
         """Visit a statement.
 
         This implementation is shared for `if`, `while`, `for`, `try`, `except`,

-        `def`, `with`, `class`, `assert` and assignments.
+        `def`, `with`, `class`, `assert`, and assignments.

 
         The relevant Python language `keywords` for a given statement will be
         NAME leaves within it. This methods puts those on a separate line.
 
         The relevant Python language `keywords` for a given statement will be
         NAME leaves within it. This methods puts those on a separate line.


@@ -136,11 +134,19 @@ class LineGenerator(Visitor[Line]):
         """
         normalize_invisible_parens(node, parens_after=parens)
         for child in node.children:
         """
         normalize_invisible_parens(node, parens_after=parens)
         for child in node.children:

-            if child.type == token.NAME and child.value in keywords:  # type: ignore
+            if is_name_token(child) and child.value in keywords:

                 yield from self.line()
 
             yield from self.visit(child)
 
                 yield from self.line()
 
             yield from self.visit(child)
 

+    def visit_match_case(self, node: Node) -> Iterator[Line]:
+        """Visit either a match or case statement."""
+        normalize_invisible_parens(node, parens_after=set())
+
+        yield from self.line()
+        for child in node.children:
+            yield from self.visit(child)
+

     def visit_suite(self, node: Node) -> Iterator[Line]:
         """Visit a suite."""
         if self.mode.is_pyi and is_stub_suite(node):
     def visit_suite(self, node: Node) -> Iterator[Line]:
         """Visit a suite."""
         if self.mode.is_pyi and is_stub_suite(node):


@@ -191,6 +197,28 @@ class LineGenerator(Visitor[Line]):
             yield from self.line()
             yield from self.visit(child)
 
             yield from self.line()
             yield from self.visit(child)
 

+    def visit_power(self, node: Node) -> Iterator[Line]:
+        for idx, leaf in enumerate(node.children[:-1]):
+            next_leaf = node.children[idx + 1]
+
+            if not isinstance(leaf, Leaf):
+                continue
+
+            value = leaf.value.lower()
+            if (
+                leaf.type == token.NUMBER
+                and next_leaf.type == syms.trailer
+                # Ensure that we are in an attribute trailer
+                and next_leaf.children[0].type == token.DOT
+                # It shouldn't wrap hexadecimal, binary and octal literals
+                and not value.startswith(("0x", "0b", "0o"))
+                # It shouldn't wrap complex literals
+                and "j" not in value
+            ):
+                wrap_in_parentheses(node, leaf)
+
+        yield from self.visit_default(node)
+

     def visit_SEMI(self, leaf: Leaf) -> Iterator[Line]:
         """Remove a semicolon and put the other statement on a separate line."""
         yield from self.line()
     def visit_SEMI(self, leaf: Leaf) -> Iterator[Line]:
         """Remove a semicolon and put the other statement on a separate line."""
         yield from self.line()


@@ -226,7 +254,7 @@ class LineGenerator(Visitor[Line]):
         if is_docstring(leaf) and "\\\n" not in leaf.value:
             # We're ignoring docstrings with backslash newline escapes because changing
             # indentation of those changes the AST representation of the code.
         if is_docstring(leaf) and "\\\n" not in leaf.value:
             # We're ignoring docstrings with backslash newline escapes because changing
             # indentation of those changes the AST representation of the code.

-            docstring = normalize_string_prefix(leaf.value, self.remove_u_prefix)
+            docstring = normalize_string_prefix(leaf.value)

             prefix = get_string_prefix(docstring)
             docstring = docstring[len(prefix) :]  # Remove the prefix
             quote_char = docstring[0]
             prefix = get_string_prefix(docstring)
             docstring = docstring[len(prefix) :]  # Remove the prefix
             quote_char = docstring[0]


@@ -292,6 +320,10 @@ class LineGenerator(Visitor[Line]):
         self.visit_async_funcdef = self.visit_async_stmt
         self.visit_decorated = self.visit_decorators
 
         self.visit_async_funcdef = self.visit_async_stmt
         self.visit_decorated = self.visit_decorators
 

+        # PEP 634
+        self.visit_match_stmt = self.visit_match_case
+        self.visit_case_block = self.visit_match_case
+

 
 def transform_line(
     line: Line, mode: Mode, features: Collection[Feature] = ()
 
 def transform_line(
     line: Line, mode: Mode, features: Collection[Feature] = ()


@@ -327,7 +359,7 @@ def transform_line(
         and not (line.inside_brackets and line.contains_standalone_comments())
     ):
         # Only apply basic string preprocessing, since lines shouldn't be split here.
         and not (line.inside_brackets and line.contains_standalone_comments())
     ):
         # Only apply basic string preprocessing, since lines shouldn't be split here.

-        if mode.experimental_string_processing:
+        if Preview.string_processing in mode:

             transformers = [string_merge, string_paren_strip]
         else:
             transformers = []
             transformers = [string_merge, string_paren_strip]
         else:
             transformers = []


@@ -335,7 +367,9 @@ def transform_line(
         transformers = [left_hand_split]
     else:
 
         transformers = [left_hand_split]
     else:
 

-        def rhs(line: Line, features: Collection[Feature]) -> Iterator[Line]:
+        def _rhs(
+            self: object, line: Line, features: Collection[Feature]
+        ) -> Iterator[Line]:

             """Wraps calls to `right_hand_split`.
 
             The calls increasingly `omit` right-hand trailers (bracket pairs with
             """Wraps calls to `right_hand_split`.
 
             The calls increasingly `omit` right-hand trailers (bracket pairs with


@@ -362,7 +396,13 @@ def transform_line(
                 line, line_length=mode.line_length, features=features
             )
 
                 line, line_length=mode.line_length, features=features
             )
 

-        if mode.experimental_string_processing:
+        # HACK: nested functions (like _rhs) compiled by mypyc don't retain their
+        # __name__ attribute which is needed in `run_transformer` further down.
+        # Unfortunately a nested class breaks mypyc too. So a class must be created
+        # via type ... https://github.com/mypyc/mypyc/issues/884
+        rhs = type("rhs", (), {"__call__": _rhs})()
+
+        if Preview.string_processing in mode:

             if line.inside_brackets:
                 transformers = [
                     string_merge,
             if line.inside_brackets:
                 transformers = [
                     string_merge,


@@ -386,6 +426,9 @@ def transform_line(
                 transformers = [delimiter_split, standalone_comment_split, rhs]
             else:
                 transformers = [rhs]
                 transformers = [delimiter_split, standalone_comment_split, rhs]
             else:
                 transformers = [rhs]

+    # It's always safe to attempt hugging of power operations and pretty much every line
+    # could match.
+    transformers.append(hug_power_op)

 
     for transform in transformers:
         # We are accumulating lines in `result` because we might want to abort
 
     for transform in transformers:
         # We are accumulating lines in `result` because we might want to abort


@@ -503,14 +546,14 @@ def right_hand_split(
             yield from right_hand_split(line, line_length, features=features, omit=omit)
             return
 
             yield from right_hand_split(line, line_length, features=features, omit=omit)
             return
 

-        except CannotSplit:
+        except CannotSplit as e:

             if not (
                 can_be_split(body)
                 or is_line_short_enough(body, line_length=line_length)
             ):
                 raise CannotSplit(
                     "Splitting failed, body is still too long and can't be split."
             if not (
                 can_be_split(body)
                 or is_line_short_enough(body, line_length=line_length)
             ):
                 raise CannotSplit(
                     "Splitting failed, body is still too long and can't be split."

-                )
+                ) from e

 
             elif head.contains_multiline_strings() or tail.contains_multiline_strings():
                 raise CannotSplit(
 
             elif head.contains_multiline_strings() or tail.contains_multiline_strings():
                 raise CannotSplit(


@@ -518,7 +561,7 @@ def right_hand_split(
                     " satisfy the splitting algorithm because the head or the tail"
                     " contains multiline strings which by definition never fit one"
                     " line."
                     " satisfy the splitting algorithm because the head or the tail"
                     " contains multiline strings which by definition never fit one"
                     " line."

-                )
+                ) from e

 
     ensure_visible(opening_bracket)
     ensure_visible(closing_bracket)
 
     ensure_visible(opening_bracket)
     ensure_visible(closing_bracket)


@@ -635,13 +678,13 @@ def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[
     try:
         last_leaf = line.leaves[-1]
     except IndexError:
     try:
         last_leaf = line.leaves[-1]
     except IndexError:

-        raise CannotSplit("Line empty")
+        raise CannotSplit("Line empty") from None

 
     bt = line.bracket_tracker
     try:
         delimiter_priority = bt.max_delimiter_priority(exclude={id(last_leaf)})
     except ValueError:
 
     bt = line.bracket_tracker
     try:
         delimiter_priority = bt.max_delimiter_priority(exclude={id(last_leaf)})
     except ValueError:

-        raise CannotSplit("No delimiters found")
+        raise CannotSplit("No delimiters found") from None

 
     if delimiter_priority == DOT_PRIORITY:
         if bt.delimiter_count_with_priority(delimiter_priority) == 1:
 
     if delimiter_priority == DOT_PRIORITY:
         if bt.delimiter_count_with_priority(delimiter_priority) == 1:


@@ -792,10 +835,11 @@ def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None:
             elif node.type == syms.import_from:
                 # "import from" nodes store parentheses directly as part of
                 # the statement
             elif node.type == syms.import_from:
                 # "import from" nodes store parentheses directly as part of
                 # the statement

-                if child.type == token.LPAR:
+                if is_lpar_token(child):
+                    assert is_rpar_token(node.children[-1])

                     # make parentheses invisible
                     # make parentheses invisible

-                    child.value = ""  # type: ignore
-                    node.children[-1].value = ""  # type: ignore
+                    child.value = ""
+                    node.children[-1].value = ""

                 elif child.type != token.STAR:
                     # insert invisible parentheses
                     node.insert_child(index, Leaf(token.LPAR, ""))
                 elif child.type != token.STAR:
                     # insert invisible parentheses
                     node.insert_child(index, Leaf(token.LPAR, ""))


@@ -840,11 +884,11 @@ def maybe_make_parens_invisible_in_atom(node: LN, parent: LN) -> bool:
 
     first = node.children[0]
     last = node.children[-1]
 
     first = node.children[0]
     last = node.children[-1]

-    if first.type == token.LPAR and last.type == token.RPAR:
+    if is_lpar_token(first) and is_rpar_token(last):

         middle = node.children[1]
         # make parentheses invisible
         middle = node.children[1]
         # make parentheses invisible

-        first.value = ""  # type: ignore
-        last.value = ""  # type: ignore
+        first.value = ""
+        last.value = ""

         maybe_make_parens_invisible_in_atom(middle, parent=parent)
 
         if is_atom_with_invisible_parens(middle):
         maybe_make_parens_invisible_in_atom(middle, parent=parent)
 
         if is_atom_with_invisible_parens(middle):


@@ -920,6 +964,7 @@ def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[Leaf
                 if (
                     prev
                     and prev.type == token.COMMA
                 if (
                     prev
                     and prev.type == token.COMMA

+                    and leaf.opening_bracket is not None

                     and not is_one_tuple_between(
                         leaf.opening_bracket, leaf, line.leaves
                     )
                     and not is_one_tuple_between(
                         leaf.opening_bracket, leaf, line.leaves
                     )


@@ -947,6 +992,7 @@ def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[Leaf
             if (
                 prev
                 and prev.type == token.COMMA
             if (
                 prev
                 and prev.type == token.COMMA

+                and leaf.opening_bracket is not None

                 and not is_one_tuple_between(leaf.opening_bracket, leaf, line.leaves)
             ):
                 # Never omit bracket pairs with trailing commas.
                 and not is_one_tuple_between(leaf.opening_bracket, leaf, line.leaves)
             ):
                 # Never omit bracket pairs with trailing commas.


@@ -976,7 +1022,7 @@ def run_transformer(
         result.extend(transform_line(transformed_line, mode=mode, features=features))
 
     if (
         result.extend(transform_line(transformed_line, mode=mode, features=features))
 
     if (

-        transform.__name__ != "rhs"
+        transform.__class__.__name__ != "rhs"

         or not line.bracket_tracker.invisible
         or any(bracket.value for bracket in line.bracket_tracker.invisible)
         or line.contains_multiline_strings()
         or not line.bracket_tracker.invisible
         or any(bracket.value for bracket in line.bracket_tracker.invisible)
         or line.contains_multiline_strings()