mirror of
https://github.com/Garmelon/PFERD.git
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61d902d715
-re-> arrows now rename their parent directories (like -->) and don't require a full match (like -exact->). Their old behaviour is available as -exact-re->. Also, this change adds the ">>" arrow head, which modifies the current path and continues to the next rule when it matches.
429 lines
11 KiB
Python
429 lines
11 KiB
Python
import ast
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import re
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from abc import ABC, abstractmethod
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from dataclasses import dataclass
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from enum import Enum
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from pathlib import PurePath
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from typing import Callable, Dict, List, Optional, Sequence, TypeVar, Union
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from .logging import log
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from .utils import fmt_path, str_path
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class ArrowHead(Enum):
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NORMAL = 0
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SEQUENCE = 1
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class Ignore:
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pass
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class Empty:
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pass
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RightSide = Union[str, Ignore, Empty]
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@dataclass
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class Transformed:
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path: PurePath
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class Ignored:
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pass
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TransformResult = Optional[Union[Transformed, Ignored]]
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@dataclass
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class Rule:
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left: str
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name: str
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head: ArrowHead
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right: RightSide
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def right_result(self, path: PurePath) -> Union[str, Transformed, Ignored]:
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if isinstance(self.right, str):
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return self.right
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elif isinstance(self.right, Ignore):
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return Ignored()
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elif isinstance(self.right, Empty):
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return Transformed(path)
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else:
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raise RuntimeError(f"Right side has invalid type {type(self.right)}")
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class Transformation(ABC):
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def __init__(self, rule: Rule):
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self.rule = rule
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@abstractmethod
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def transform(self, path: PurePath) -> TransformResult:
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pass
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class ExactTf(Transformation):
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def transform(self, path: PurePath) -> TransformResult:
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if path != PurePath(self.rule.left):
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return None
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right = self.rule.right_result(path)
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if not isinstance(right, str):
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return right
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return Transformed(PurePath(right))
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class ExactReTf(Transformation):
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def transform(self, path: PurePath) -> TransformResult:
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match = re.fullmatch(self.rule.left, str_path(path))
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if not match:
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return None
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right = self.rule.right_result(path)
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if not isinstance(right, str):
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return right
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# For some reason, mypy thinks that "groups" has type List[str]. But
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# since elements of "match.groups()" can be None, mypy is wrong.
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groups: Sequence[Optional[str]] = [match[0]] + list(match.groups())
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locals_dir: Dict[str, Union[str, int, float]] = {}
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for i, group in enumerate(groups):
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if group is None:
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continue
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locals_dir[f"g{i}"] = group
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try:
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locals_dir[f"i{i}"] = int(group)
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except ValueError:
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pass
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try:
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locals_dir[f"f{i}"] = float(group)
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except ValueError:
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pass
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result = eval(f"f{right!r}", {}, locals_dir)
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return Transformed(PurePath(result))
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class RenamingParentsTf(Transformation):
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def __init__(self, sub_tf: Transformation):
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super().__init__(sub_tf.rule)
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self.sub_tf = sub_tf
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def transform(self, path: PurePath) -> TransformResult:
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for i in range(len(path.parts), -1, -1):
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parent = PurePath(*path.parts[:i])
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child = PurePath(*path.parts[i:])
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transformed = self.sub_tf.transform(parent)
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if not transformed:
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continue
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elif isinstance(transformed, Transformed):
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return Transformed(transformed.path / child)
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elif isinstance(transformed, Ignored):
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return transformed
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else:
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raise RuntimeError(f"Invalid transform result of type {type(transformed)}: {transformed}")
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return None
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class RenamingPartsTf(Transformation):
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def __init__(self, sub_tf: Transformation):
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super().__init__(sub_tf.rule)
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self.sub_tf = sub_tf
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def transform(self, path: PurePath) -> TransformResult:
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result = PurePath()
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for part in path.parts:
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transformed = self.sub_tf.transform(PurePath(part))
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if not transformed:
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result /= part
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elif isinstance(transformed, Transformed):
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result /= transformed.path
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elif isinstance(transformed, Ignored):
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return transformed
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else:
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raise RuntimeError(f"Invalid transform result of type {type(transformed)}: {transformed}")
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return None
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class RuleParseError(Exception):
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def __init__(self, line: "Line", reason: str):
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super().__init__(f"Error in rule on line {line.line_nr}, column {line.index}: {reason}")
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self.line = line
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self.reason = reason
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def pretty_print(self) -> None:
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log.error(f"Error parsing rule on line {self.line.line_nr}:")
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log.error_contd(self.line.line)
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spaces = " " * self.line.index
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log.error_contd(f"{spaces}^--- {self.reason}")
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T = TypeVar("T")
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class Line:
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def __init__(self, line: str, line_nr: int):
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self._line = line
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self._line_nr = line_nr
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self._index = 0
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@property
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def line(self) -> str:
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return self._line
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@property
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def line_nr(self) -> int:
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return self._line_nr
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@property
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def index(self) -> int:
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return self._index
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@index.setter
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def index(self, index: int) -> None:
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self._index = index
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@property
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def rest(self) -> str:
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return self.line[self.index:]
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def peek(self, amount: int = 1) -> str:
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return self.rest[:amount]
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def take(self, amount: int = 1) -> str:
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string = self.peek(amount)
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self.index += len(string)
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return string
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def expect(self, string: str) -> str:
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if self.peek(len(string)) == string:
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return self.take(len(string))
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else:
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raise RuleParseError(self, f"Expected {string!r}")
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def expect_with(self, string: str, value: T) -> T:
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self.expect(string)
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return value
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def one_of(self, parsers: List[Callable[[], T]], description: str) -> T:
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for parser in parsers:
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index = self.index
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try:
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return parser()
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except RuleParseError:
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self.index = index
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raise RuleParseError(self, description)
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# RULE = LEFT SPACE '-' NAME '-' HEAD (SPACE RIGHT)?
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# SPACE = ' '+
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# NAME = '' | 'exact' | 'name' | 're' | 'exact-re' | 'name-re'
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# HEAD = '>' | '>>'
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# LEFT = STR | QUOTED_STR
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# RIGHT = STR | QUOTED_STR | '!'
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def parse_zero_or_more_spaces(line: Line) -> None:
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while line.peek() == " ":
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line.take()
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def parse_one_or_more_spaces(line: Line) -> None:
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line.expect(" ")
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parse_zero_or_more_spaces(line)
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def parse_str(line: Line) -> str:
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result = []
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while c := line.peek():
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if c == " ":
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break
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else:
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line.take()
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result.append(c)
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if result:
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return "".join(result)
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else:
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raise RuleParseError(line, "Expected non-space character")
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QUOTATION_MARKS = {'"', "'"}
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def parse_quoted_str(line: Line) -> str:
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escaped = False
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# Points to first character of string literal
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start_index = line.index
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quotation_mark = line.peek()
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if quotation_mark not in QUOTATION_MARKS:
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raise RuleParseError(line, "Expected quotation mark")
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line.take()
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while c := line.peek():
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if escaped:
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escaped = False
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line.take()
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elif c == quotation_mark:
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line.take()
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stop_index = line.index
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literal = line.line[start_index:stop_index]
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try:
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return ast.literal_eval(literal)
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except SyntaxError as e:
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line.index = start_index
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raise RuleParseError(line, str(e)) from e
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elif c == "\\":
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escaped = True
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line.take()
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else:
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line.take()
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raise RuleParseError(line, "Expected end of string literal")
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def parse_left(line: Line) -> str:
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if line.peek() in QUOTATION_MARKS:
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return parse_quoted_str(line)
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else:
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return parse_str(line)
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def parse_right(line: Line) -> Union[str, Ignore]:
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c = line.peek()
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if c in QUOTATION_MARKS:
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return parse_quoted_str(line)
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else:
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string = parse_str(line)
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if string == "!":
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return Ignore()
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return string
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def parse_arrow_name(line: Line) -> str:
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return line.one_of([
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lambda: line.expect("exact-re"),
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lambda: line.expect("exact"),
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lambda: line.expect("name-re"),
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lambda: line.expect("name"),
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lambda: line.expect("re"),
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lambda: line.expect(""),
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], "Expected arrow name")
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def parse_arrow_head(line: Line) -> ArrowHead:
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return line.one_of([
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lambda: line.expect_with(">>", ArrowHead.SEQUENCE),
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lambda: line.expect_with(">", ArrowHead.NORMAL),
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], "Expected arrow head")
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def parse_eol(line: Line) -> None:
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if line.peek():
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raise RuleParseError(line, "Expected end of line")
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def parse_rule(line: Line) -> Rule:
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parse_zero_or_more_spaces(line)
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left = parse_left(line)
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parse_one_or_more_spaces(line)
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line.expect("-")
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name = parse_arrow_name(line)
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line.expect("-")
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head = parse_arrow_head(line)
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index = line.index
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right: RightSide
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try:
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parse_zero_or_more_spaces(line)
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parse_eol(line)
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right = Empty()
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except RuleParseError:
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line.index = index
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parse_one_or_more_spaces(line)
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right = parse_right(line)
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parse_eol(line)
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return Rule(left, name, head, right)
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def parse_transformation(line: Line) -> Transformation:
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rule = parse_rule(line)
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if rule.name == "":
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return RenamingParentsTf(ExactTf(rule))
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elif rule.name == "exact":
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return ExactTf(rule)
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elif rule.name == "name":
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return RenamingPartsTf(ExactTf(rule))
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elif rule.name == "re":
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return RenamingParentsTf(ExactReTf(rule))
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elif rule.name == "exact-re":
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return ExactReTf(rule)
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elif rule.name == "name-re":
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return RenamingPartsTf(ExactReTf(rule))
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else:
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raise RuntimeError(f"Invalid arrow name {rule.name!r}")
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class Transformer:
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def __init__(self, rules: str):
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"""
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May throw a RuleParseException.
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"""
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self._tfs = []
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for i, line in enumerate(rules.split("\n")):
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line = line.strip()
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if line:
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tf = parse_transformation(Line(line, i))
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self._tfs.append((line, tf))
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def transform(self, path: PurePath) -> Optional[PurePath]:
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for i, (line, tf) in enumerate(self._tfs):
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log.explain(f"Testing rule {i+1}: {line}")
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try:
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result = tf.transform(path)
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except Exception as e:
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log.warn(f"Error while testing rule {i+1}: {line}")
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log.warn_contd(str(e))
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continue
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if not result:
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continue
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if isinstance(result, Ignored):
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log.explain("Match found, path ignored")
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return None
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if tf.rule.head == ArrowHead.NORMAL:
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log.explain(f"Match found, transformed path to {fmt_path(result.path)}")
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path = result.path
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break
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elif tf.rule.head == ArrowHead.SEQUENCE:
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log.explain(f"Match found, updated path to {fmt_path(result.path)}")
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path = result.path
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else:
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raise RuntimeError(f"Invalid transform result of type {type(result)}: {result}")
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log.explain(f"Final result: {fmt_path(path)}")
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return path
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