Overhaul transform logic

-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.
This commit is contained in:
Joscha 2021-06-09 17:42:38 +02:00
parent 8ab462fb87
commit 61d902d715
2 changed files with 298 additions and 245 deletions

View File

@ -24,8 +24,11 @@ ambiguous situations.
### Added
- `skip` option for crawlers
- Rules with `>>` instead of `>` as arrow head
- `-exact-re->` arrow (behaves like `-re->` did previously)
### Changed
- The `-re->` arrow can now rename directories (like `-->`)
- Use `/` instead of `\` as path separator for (regex) rules on Windows
- Use the label to the left for exercises instead of the button name to
determine the folder name

View File

@ -1,151 +1,159 @@
# I'm sorry that this code has become a bit dense and unreadable. While
# reading, it is important to remember what True and False mean. I'd love to
# have some proper sum-types for the inputs and outputs, they'd make this code
# a lot easier to understand.
import ast
import re
from abc import ABC, abstractmethod
from dataclasses import dataclass
from enum import Enum
from pathlib import PurePath
from typing import Dict, Optional, Sequence, Union
from typing import Callable, Dict, List, Optional, Sequence, TypeVar, Union
from .logging import log
from .utils import fmt_path, str_path
class Rule(ABC):
@abstractmethod
def transform(self, path: PurePath) -> Union[PurePath, bool]:
"""
Try to apply this rule to the path. Returns another path if the rule
was successfully applied, True if the rule matched but resulted in an
exclamation mark, and False if the rule didn't match at all.
"""
class ArrowHead(Enum):
NORMAL = 0
SEQUENCE = 1
class Ignore:
pass
# These rules all use a Union[T, bool] for their right side. They are passed a
# T if the arrow's right side was a normal string, True if it was an
# exclamation mark and False if it was missing entirely.
class Empty:
pass
class NormalRule(Rule):
def __init__(self, left: PurePath, right: Union[PurePath, bool]):
self._left = left
self._right = right
RightSide = Union[str, Ignore, Empty]
def _match_prefix(self, path: PurePath) -> Optional[PurePath]:
left_parts = list(reversed(self._left.parts))
path_parts = list(reversed(path.parts))
if len(left_parts) > len(path_parts):
@dataclass
class Transformed:
path: PurePath
class Ignored:
pass
TransformResult = Optional[Union[Transformed, Ignored]]
@dataclass
class Rule:
left: str
name: str
head: ArrowHead
right: RightSide
def right_result(self, path: PurePath) -> Union[str, Transformed, Ignored]:
if isinstance(self.right, str):
return self.right
elif isinstance(self.right, Ignore):
return Ignored()
elif isinstance(self.right, Empty):
return Transformed(path)
else:
raise RuntimeError(f"Right side has invalid type {type(self.right)}")
class Transformation(ABC):
def __init__(self, rule: Rule):
self.rule = rule
@abstractmethod
def transform(self, path: PurePath) -> TransformResult:
pass
class ExactTf(Transformation):
def transform(self, path: PurePath) -> TransformResult:
if path != PurePath(self.rule.left):
return None
while left_parts and path_parts:
left_part = left_parts.pop()
path_part = path_parts.pop()
right = self.rule.right_result(path)
if not isinstance(right, str):
return right
if left_part != path_part:
return Transformed(PurePath(right))
class ExactReTf(Transformation):
def transform(self, path: PurePath) -> TransformResult:
match = re.fullmatch(self.rule.left, str_path(path))
if not match:
return None
if left_parts:
return None
right = self.rule.right_result(path)
if not isinstance(right, str):
return right
path_parts.reverse()
return PurePath(*path_parts)
def transform(self, path: PurePath) -> Union[PurePath, bool]:
if rest := self._match_prefix(path):
if isinstance(self._right, bool):
return self._right or path
else:
return self._right / rest
return False
class ExactRule(Rule):
def __init__(self, left: PurePath, right: Union[PurePath, bool]):
self._left = left
self._right = right
def transform(self, path: PurePath) -> Union[PurePath, bool]:
if path == self._left:
if isinstance(self._right, bool):
return self._right or path
else:
return self._right
return False
class NameRule(Rule):
def __init__(self, subrule: Rule):
self._subrule = subrule
def transform(self, path: PurePath) -> Union[PurePath, bool]:
matched = False
result = PurePath()
for part in path.parts:
part_result = self._subrule.transform(PurePath(part))
if isinstance(part_result, PurePath):
matched = True
result /= part_result
elif part_result:
# If any subrule call ignores its path segment, the entire path
# should be ignored
return True
else:
# The subrule doesn't modify this segment, but maybe other
# segments
result /= part
if matched:
return result
else:
# The subrule has modified no segments, so this name version of it
# doesn't match
return False
class ReRule(Rule):
def __init__(self, left: str, right: Union[str, bool]):
self._left = left
self._right = right
def transform(self, path: PurePath) -> Union[PurePath, bool]:
if match := re.fullmatch(self._left, str_path(path)):
if isinstance(self._right, bool):
return self._right or path
vars: Dict[str, Union[str, int, float]] = {}
# For some reason, mypy thinks that "groups" has type List[str].
# But since elements of "match.groups()" can be None, mypy is
# wrong.
# For some reason, mypy thinks that "groups" has type List[str]. But
# since elements of "match.groups()" can be None, mypy is wrong.
groups: Sequence[Optional[str]] = [match[0]] + list(match.groups())
locals_dir: Dict[str, Union[str, int, float]] = {}
for i, group in enumerate(groups):
if group is None:
continue
vars[f"g{i}"] = group
locals_dir[f"g{i}"] = group
try:
vars[f"i{i}"] = int(group)
locals_dir[f"i{i}"] = int(group)
except ValueError:
pass
try:
vars[f"f{i}"] = float(group)
locals_dir[f"f{i}"] = float(group)
except ValueError:
pass
result = eval(f"f{self._right!r}", vars)
return PurePath(result)
result = eval(f"f{right!r}", {}, locals_dir)
return Transformed(PurePath(result))
return False
class RenamingParentsTf(Transformation):
def __init__(self, sub_tf: Transformation):
super().__init__(sub_tf.rule)
self.sub_tf = sub_tf
def transform(self, path: PurePath) -> TransformResult:
for i in range(len(path.parts), -1, -1):
parent = PurePath(*path.parts[:i])
child = PurePath(*path.parts[i:])
transformed = self.sub_tf.transform(parent)
if not transformed:
continue
elif isinstance(transformed, Transformed):
return Transformed(transformed.path / child)
elif isinstance(transformed, Ignored):
return transformed
else:
raise RuntimeError(f"Invalid transform result of type {type(transformed)}: {transformed}")
return None
class RenamingPartsTf(Transformation):
def __init__(self, sub_tf: Transformation):
super().__init__(sub_tf.rule)
self.sub_tf = sub_tf
def transform(self, path: PurePath) -> TransformResult:
result = PurePath()
for part in path.parts:
transformed = self.sub_tf.transform(PurePath(part))
if not transformed:
result /= part
elif isinstance(transformed, Transformed):
result /= transformed.path
elif isinstance(transformed, Ignored):
return transformed
else:
raise RuntimeError(f"Invalid transform result of type {type(transformed)}: {transformed}")
return None
class RuleParseError(Exception):
@ -162,18 +170,15 @@ class RuleParseError(Exception):
log.error_contd(f"{spaces}^--- {self.reason}")
T = TypeVar("T")
class Line:
def __init__(self, line: str, line_nr: int):
self._line = line
self._line_nr = line_nr
self._index = 0
def get(self) -> Optional[str]:
if self._index < len(self._line):
return self._line[self._index]
return None
@property
def line(self) -> str:
return self._line
@ -190,155 +195,192 @@ class Line:
def index(self, index: int) -> None:
self._index = index
def advance(self) -> None:
self._index += 1
@property
def rest(self) -> str:
return self.line[self.index:]
def expect(self, string: str) -> None:
for char in string:
if self.get() == char:
self.advance()
def peek(self, amount: int = 1) -> str:
return self.rest[:amount]
def take(self, amount: int = 1) -> str:
string = self.peek(amount)
self.index += len(string)
return string
def expect(self, string: str) -> str:
if self.peek(len(string)) == string:
return self.take(len(string))
else:
raise RuleParseError(self, f"Expected {char!r}")
raise RuleParseError(self, f"Expected {string!r}")
def expect_with(self, string: str, value: T) -> T:
self.expect(string)
return value
def one_of(self, parsers: List[Callable[[], T]], description: str) -> T:
for parser in parsers:
index = self.index
try:
return parser()
except RuleParseError:
self.index = index
raise RuleParseError(self, description)
# RULE = LEFT SPACE '-' NAME '-' HEAD (SPACE RIGHT)?
# SPACE = ' '+
# NAME = '' | 'exact' | 'name' | 're' | 'exact-re' | 'name-re'
# HEAD = '>' | '>>'
# LEFT = STR | QUOTED_STR
# RIGHT = STR | QUOTED_STR | '!'
def parse_zero_or_more_spaces(line: Line) -> None:
while line.peek() == " ":
line.take()
def parse_one_or_more_spaces(line: Line) -> None:
line.expect(" ")
parse_zero_or_more_spaces(line)
def parse_str(line: Line) -> str:
result = []
while c := line.peek():
if c == " ":
break
else:
line.take()
result.append(c)
if result:
return "".join(result)
else:
raise RuleParseError(line, "Expected non-space character")
QUOTATION_MARKS = {'"', "'"}
def parse_string_literal(line: Line) -> str:
def parse_quoted_str(line: Line) -> str:
escaped = False
# Points to first character of string literal
start_index = line.index
quotation_mark = line.get()
quotation_mark = line.peek()
if quotation_mark not in QUOTATION_MARKS:
# This should never happen as long as this function is only called from
# parse_string.
raise RuleParseError(line, "Invalid quotation mark")
line.advance()
raise RuleParseError(line, "Expected quotation mark")
line.take()
while c := line.get():
while c := line.peek():
if escaped:
escaped = False
line.advance()
line.take()
elif c == quotation_mark:
line.advance()
line.take()
stop_index = line.index
literal = line.line[start_index:stop_index]
try:
return ast.literal_eval(literal)
except SyntaxError as e:
line.index = start_index
raise RuleParseError(line, str(e)) from e
elif c == "\\":
escaped = True
line.advance()
line.take()
else:
line.advance()
line.take()
raise RuleParseError(line, "Expected end of string literal")
def parse_until_space_or_eol(line: Line) -> str:
result = []
while c := line.get():
if c == " ":
break
result.append(c)
line.advance()
return "".join(result)
def parse_string(line: Line) -> Union[str, bool]:
if line.get() in QUOTATION_MARKS:
return parse_string_literal(line)
def parse_left(line: Line) -> str:
if line.peek() in QUOTATION_MARKS:
return parse_quoted_str(line)
else:
string = parse_until_space_or_eol(line)
return parse_str(line)
def parse_right(line: Line) -> Union[str, Ignore]:
c = line.peek()
if c in QUOTATION_MARKS:
return parse_quoted_str(line)
else:
string = parse_str(line)
if string == "!":
return True
return Ignore()
return string
def parse_arrow(line: Line) -> str:
line.expect("-")
name = []
while True:
c = line.get()
if not c:
raise RuleParseError(line, "Expected rest of arrow")
elif c == "-":
line.advance()
c = line.get()
if not c:
raise RuleParseError(line, "Expected rest of arrow")
elif c == ">":
line.advance()
break # End of arrow
else:
name.append("-")
continue
else:
name.append(c)
line.advance()
return "".join(name)
def parse_arrow_name(line: Line) -> str:
return line.one_of([
lambda: line.expect("exact-re"),
lambda: line.expect("exact"),
lambda: line.expect("name-re"),
lambda: line.expect("name"),
lambda: line.expect("re"),
lambda: line.expect(""),
], "Expected arrow name")
def parse_whitespace(line: Line) -> None:
line.expect(" ")
while line.get() == " ":
line.advance()
def parse_arrow_head(line: Line) -> ArrowHead:
return line.one_of([
lambda: line.expect_with(">>", ArrowHead.SEQUENCE),
lambda: line.expect_with(">", ArrowHead.NORMAL),
], "Expected arrow head")
def parse_eol(line: Line) -> None:
if line.get() is not None:
if line.peek():
raise RuleParseError(line, "Expected end of line")
def parse_rule(line: Line) -> Rule:
# Parse left side
leftindex = line.index
left = parse_string(line)
if isinstance(left, bool):
line.index = leftindex
raise RuleParseError(line, "Left side can't be '!'")
leftpath = PurePath(left)
parse_zero_or_more_spaces(line)
left = parse_left(line)
# Parse arrow
parse_whitespace(line)
arrowindex = line.index
arrowname = parse_arrow(line)
parse_one_or_more_spaces(line)
# Parse right side
if line.get():
parse_whitespace(line)
right = parse_string(line)
else:
right = False
rightpath: Union[PurePath, bool]
if isinstance(right, bool):
rightpath = right
else:
rightpath = PurePath(right)
line.expect("-")
name = parse_arrow_name(line)
line.expect("-")
head = parse_arrow_head(line)
index = line.index
right: RightSide
try:
parse_zero_or_more_spaces(line)
parse_eol(line)
right = Empty()
except RuleParseError:
line.index = index
parse_one_or_more_spaces(line)
right = parse_right(line)
parse_eol(line)
# Dispatch
if arrowname == "":
return NormalRule(leftpath, rightpath)
elif arrowname == "name":
if len(leftpath.parts) > 1:
line.index = leftindex
raise RuleParseError(line, "SOURCE must be a single name, not multiple segments")
return NameRule(ExactRule(leftpath, rightpath))
elif arrowname == "exact":
return ExactRule(leftpath, rightpath)
elif arrowname == "re":
return ReRule(left, right)
elif arrowname == "name-re":
return NameRule(ReRule(left, right))
return Rule(left, name, head, right)
def parse_transformation(line: Line) -> Transformation:
rule = parse_rule(line)
if rule.name == "":
return RenamingParentsTf(ExactTf(rule))
elif rule.name == "exact":
return ExactTf(rule)
elif rule.name == "name":
return RenamingPartsTf(ExactTf(rule))
elif rule.name == "re":
return RenamingParentsTf(ExactReTf(rule))
elif rule.name == "exact-re":
return ExactReTf(rule)
elif rule.name == "name-re":
return RenamingPartsTf(ExactReTf(rule))
else:
line.index = arrowindex + 1 # For nicer error message
raise RuleParseError(line, f"Invalid arrow name {arrowname!r}")
raise RuntimeError(f"Invalid arrow name {rule.name!r}")
class Transformer:
@ -347,32 +389,40 @@ class Transformer:
May throw a RuleParseException.
"""
self._rules = []
self._tfs = []
for i, line in enumerate(rules.split("\n")):
line = line.strip()
if line:
rule = parse_rule(Line(line, i))
self._rules.append((line, rule))
tf = parse_transformation(Line(line, i))
self._tfs.append((line, tf))
def transform(self, path: PurePath) -> Optional[PurePath]:
for i, (line, rule) in enumerate(self._rules):
for i, (line, tf) in enumerate(self._tfs):
log.explain(f"Testing rule {i+1}: {line}")
try:
result = rule.transform(path)
result = tf.transform(path)
except Exception as e:
log.warn(f"Error while testing rule {i+1}: {line}")
log.warn_contd(str(e))
continue
if isinstance(result, PurePath):
log.explain(f"Match found, transformed path to {fmt_path(result)}")
return result
elif result: # Exclamation mark
log.explain("Match found, path ignored")
return None
else:
if not result:
continue
log.explain("No rule matched, path is unchanged")
if isinstance(result, Ignored):
log.explain("Match found, path ignored")
return None
if tf.rule.head == ArrowHead.NORMAL:
log.explain(f"Match found, transformed path to {fmt_path(result.path)}")
path = result.path
break
elif tf.rule.head == ArrowHead.SEQUENCE:
log.explain(f"Match found, updated path to {fmt_path(result.path)}")
path = result.path
else:
raise RuntimeError(f"Invalid transform result of type {type(result)}: {result}")
log.explain(f"Final result: {fmt_path(path)}")
return path