343 lines
10 KiB
Python
343 lines
10 KiB
Python
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"""Builds on top of nodes.py to track brackets."""
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import sys
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from dataclasses import dataclass, field
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from typing import Dict, Iterable, List, Optional, Tuple, Union
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if sys.version_info < (3, 8):
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from typing_extensions import Final
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else:
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from typing import Final
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from black.nodes import (
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BRACKET,
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CLOSING_BRACKETS,
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COMPARATORS,
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LOGIC_OPERATORS,
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MATH_OPERATORS,
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OPENING_BRACKETS,
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UNPACKING_PARENTS,
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VARARGS_PARENTS,
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is_vararg,
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syms,
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)
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from blib2to3.pgen2 import token
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from blib2to3.pytree import Leaf, Node
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# types
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LN = Union[Leaf, Node]
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Depth = int
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LeafID = int
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NodeType = int
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Priority = int
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COMPREHENSION_PRIORITY: Final = 20
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COMMA_PRIORITY: Final = 18
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TERNARY_PRIORITY: Final = 16
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LOGIC_PRIORITY: Final = 14
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STRING_PRIORITY: Final = 12
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COMPARATOR_PRIORITY: Final = 10
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MATH_PRIORITIES: Final = {
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token.VBAR: 9,
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token.CIRCUMFLEX: 8,
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token.AMPER: 7,
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token.LEFTSHIFT: 6,
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token.RIGHTSHIFT: 6,
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token.PLUS: 5,
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token.MINUS: 5,
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token.STAR: 4,
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token.SLASH: 4,
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token.DOUBLESLASH: 4,
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token.PERCENT: 4,
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token.AT: 4,
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token.TILDE: 3,
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token.DOUBLESTAR: 2,
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}
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DOT_PRIORITY: Final = 1
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class BracketMatchError(Exception):
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"""Raised when an opening bracket is unable to be matched to a closing bracket."""
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@dataclass
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class BracketTracker:
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"""Keeps track of brackets on a line."""
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depth: int = 0
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bracket_match: Dict[Tuple[Depth, NodeType], Leaf] = field(default_factory=dict)
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delimiters: Dict[LeafID, Priority] = field(default_factory=dict)
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previous: Optional[Leaf] = None
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_for_loop_depths: List[int] = field(default_factory=list)
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_lambda_argument_depths: List[int] = field(default_factory=list)
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invisible: List[Leaf] = field(default_factory=list)
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def mark(self, leaf: Leaf) -> None:
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"""Mark `leaf` with bracket-related metadata. Keep track of delimiters.
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All leaves receive an int `bracket_depth` field that stores how deep
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within brackets a given leaf is. 0 means there are no enclosing brackets
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that started on this line.
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If a leaf is itself a closing bracket, it receives an `opening_bracket`
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field that it forms a pair with. This is a one-directional link to
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avoid reference cycles.
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If a leaf is a delimiter (a token on which Black can split the line if
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needed) and it's on depth 0, its `id()` is stored in the tracker's
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`delimiters` field.
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"""
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if leaf.type == token.COMMENT:
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return
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self.maybe_decrement_after_for_loop_variable(leaf)
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self.maybe_decrement_after_lambda_arguments(leaf)
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if leaf.type in CLOSING_BRACKETS:
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self.depth -= 1
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try:
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opening_bracket = self.bracket_match.pop((self.depth, leaf.type))
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except KeyError as e:
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raise BracketMatchError(
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"Unable to match a closing bracket to the following opening"
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f" bracket: {leaf}"
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) from e
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leaf.opening_bracket = opening_bracket
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if not leaf.value:
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self.invisible.append(leaf)
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leaf.bracket_depth = self.depth
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if self.depth == 0:
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delim = is_split_before_delimiter(leaf, self.previous)
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if delim and self.previous is not None:
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self.delimiters[id(self.previous)] = delim
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else:
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delim = is_split_after_delimiter(leaf, self.previous)
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if delim:
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self.delimiters[id(leaf)] = delim
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if leaf.type in OPENING_BRACKETS:
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self.bracket_match[self.depth, BRACKET[leaf.type]] = leaf
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self.depth += 1
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if not leaf.value:
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self.invisible.append(leaf)
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self.previous = leaf
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self.maybe_increment_lambda_arguments(leaf)
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self.maybe_increment_for_loop_variable(leaf)
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def any_open_brackets(self) -> bool:
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"""Return True if there is an yet unmatched open bracket on the line."""
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return bool(self.bracket_match)
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def max_delimiter_priority(self, exclude: Iterable[LeafID] = ()) -> Priority:
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"""Return the highest priority of a delimiter found on the line.
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Values are consistent with what `is_split_*_delimiter()` return.
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Raises ValueError on no delimiters.
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"""
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return max(v for k, v in self.delimiters.items() if k not in exclude)
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def delimiter_count_with_priority(self, priority: Priority = 0) -> int:
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"""Return the number of delimiters with the given `priority`.
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If no `priority` is passed, defaults to max priority on the line.
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"""
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if not self.delimiters:
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return 0
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priority = priority or self.max_delimiter_priority()
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return sum(1 for p in self.delimiters.values() if p == priority)
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def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool:
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"""In a for loop, or comprehension, the variables are often unpacks.
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To avoid splitting on the comma in this situation, increase the depth of
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tokens between `for` and `in`.
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"""
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if leaf.type == token.NAME and leaf.value == "for":
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self.depth += 1
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self._for_loop_depths.append(self.depth)
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return True
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return False
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def maybe_decrement_after_for_loop_variable(self, leaf: Leaf) -> bool:
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"""See `maybe_increment_for_loop_variable` above for explanation."""
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if (
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self._for_loop_depths
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and self._for_loop_depths[-1] == self.depth
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and leaf.type == token.NAME
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and leaf.value == "in"
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):
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self.depth -= 1
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self._for_loop_depths.pop()
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return True
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return False
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def maybe_increment_lambda_arguments(self, leaf: Leaf) -> bool:
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"""In a lambda expression, there might be more than one argument.
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To avoid splitting on the comma in this situation, increase the depth of
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tokens between `lambda` and `:`.
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"""
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if leaf.type == token.NAME and leaf.value == "lambda":
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self.depth += 1
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self._lambda_argument_depths.append(self.depth)
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return True
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return False
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def maybe_decrement_after_lambda_arguments(self, leaf: Leaf) -> bool:
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"""See `maybe_increment_lambda_arguments` above for explanation."""
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if (
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self._lambda_argument_depths
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and self._lambda_argument_depths[-1] == self.depth
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and leaf.type == token.COLON
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):
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self.depth -= 1
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self._lambda_argument_depths.pop()
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return True
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return False
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def get_open_lsqb(self) -> Optional[Leaf]:
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"""Return the most recent opening square bracket (if any)."""
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return self.bracket_match.get((self.depth - 1, token.RSQB))
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def is_split_after_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority:
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"""Return the priority of the `leaf` delimiter, given a line break after it.
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The delimiter priorities returned here are from those delimiters that would
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cause a line break after themselves.
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Higher numbers are higher priority.
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"""
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if leaf.type == token.COMMA:
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return COMMA_PRIORITY
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return 0
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def is_split_before_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority:
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"""Return the priority of the `leaf` delimiter, given a line break before it.
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The delimiter priorities returned here are from those delimiters that would
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cause a line break before themselves.
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Higher numbers are higher priority.
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"""
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if is_vararg(leaf, within=VARARGS_PARENTS | UNPACKING_PARENTS):
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# * and ** might also be MATH_OPERATORS but in this case they are not.
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# Don't treat them as a delimiter.
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return 0
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if (
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leaf.type == token.DOT
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and leaf.parent
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and leaf.parent.type not in {syms.import_from, syms.dotted_name}
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and (previous is None or previous.type in CLOSING_BRACKETS)
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):
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return DOT_PRIORITY
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if (
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leaf.type in MATH_OPERATORS
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and leaf.parent
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and leaf.parent.type not in {syms.factor, syms.star_expr}
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):
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return MATH_PRIORITIES[leaf.type]
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if leaf.type in COMPARATORS:
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return COMPARATOR_PRIORITY
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if (
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leaf.type == token.STRING
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and previous is not None
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and previous.type == token.STRING
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):
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return STRING_PRIORITY
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if leaf.type not in {token.NAME, token.ASYNC}:
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return 0
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if (
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leaf.value == "for"
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and leaf.parent
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and leaf.parent.type in {syms.comp_for, syms.old_comp_for}
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or leaf.type == token.ASYNC
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):
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if (
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not isinstance(leaf.prev_sibling, Leaf)
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or leaf.prev_sibling.value != "async"
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):
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return COMPREHENSION_PRIORITY
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if (
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leaf.value == "if"
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and leaf.parent
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and leaf.parent.type in {syms.comp_if, syms.old_comp_if}
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):
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return COMPREHENSION_PRIORITY
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if leaf.value in {"if", "else"} and leaf.parent and leaf.parent.type == syms.test:
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return TERNARY_PRIORITY
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if leaf.value == "is":
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return COMPARATOR_PRIORITY
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if (
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leaf.value == "in"
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and leaf.parent
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and leaf.parent.type in {syms.comp_op, syms.comparison}
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and not (
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previous is not None
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and previous.type == token.NAME
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and previous.value == "not"
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)
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):
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return COMPARATOR_PRIORITY
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if (
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leaf.value == "not"
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and leaf.parent
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and leaf.parent.type == syms.comp_op
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and not (
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previous is not None
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and previous.type == token.NAME
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and previous.value == "is"
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)
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):
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return COMPARATOR_PRIORITY
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if leaf.value in LOGIC_OPERATORS and leaf.parent:
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return LOGIC_PRIORITY
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return 0
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def max_delimiter_priority_in_atom(node: LN) -> Priority:
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"""Return maximum delimiter priority inside `node`.
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This is specific to atoms with contents contained in a pair of parentheses.
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If `node` isn't an atom or there are no enclosing parentheses, returns 0.
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"""
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if node.type != syms.atom:
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return 0
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first = node.children[0]
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last = node.children[-1]
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if not (first.type == token.LPAR and last.type == token.RPAR):
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return 0
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bt = BracketTracker()
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for c in node.children[1:-1]:
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if isinstance(c, Leaf):
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bt.mark(c)
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else:
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for leaf in c.leaves():
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bt.mark(leaf)
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try:
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return bt.max_delimiter_priority()
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except ValueError:
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return 0
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