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from __future__ import annotations
import dataclasses
import re
from typing import (
Any,
Callable,
Generic,
IO,
Iterable,
Optional,
overload,
TypeVar,
TYPE_CHECKING,
)
_T = TypeVar('_T')
if TYPE_CHECKING:
from dataclasses import _DataclassT
else:
# We can only get to _DataclassT during type checking, use a generic type during runtime
_DataclassT = _T
__all__ = [
'field_deb822',
'read_deb822',
'write_deb822',
'Deb822DecodeError',
]
class Deb822Field(Generic[_T]):
key: str
load: Optional[Callable[[str], _T]]
dump: Optional[Callable[[_T], str]]
def __init__(
self, *,
key: str,
load: Optional[Callable[[str], _T]],
dump: Optional[Callable[[_T], str]],
) -> None:
self.key = key
self.load = load
self.dump = dump
# The return type _T is technically wrong, but it allows checking if during
# runtime we get the correct type.
@overload
def field_deb822(
deb822_key: str,
/, *,
deb822_load: Optional[Callable[[str], _T]] = None,
deb822_dump: Optional[Callable[[_T], str]] = str,
default: _T,
) -> _T:
...
@overload
def field_deb822(
deb822_key: str,
/, *,
deb822_load: Optional[Callable[[str], _T]] = None,
deb822_dump: Optional[Callable[[_T], str]] = str,
default_factory: Callable[[], _T],
) -> _T:
...
@overload
def field_deb822(
deb822_key: str,
/, *,
deb822_load: Optional[Callable[[str], _T]] = None,
deb822_dump: Optional[Callable[[_T], str]] = str,
) -> _T:
...
def field_deb822(
deb822_key: str,
/, *,
deb822_load: Optional[Callable[[str], _T]] = None,
deb822_dump: Optional[Callable[[_T], str]] = str,
default: Any = dataclasses.MISSING,
default_factory: Any = dataclasses.MISSING,
) -> Any:
metadata: dict[str, Any] = {
'deb822': Deb822Field(
key=deb822_key,
load=deb822_load,
dump=deb822_dump,
),
}
if default is not dataclasses.MISSING:
return dataclasses.field(
default=default,
metadata=metadata,
)
else:
return dataclasses.field(
default_factory=default_factory,
metadata=metadata,
)
class Deb822DecodeError(ValueError):
pass
class Deb822DecodeState(Generic[_DataclassT]):
cls: type[_DataclassT]
fields: dict[str, dataclasses.Field]
ignore_unknown: bool
data: dict[Optional[dataclasses.Field], str]
current: Optional[dataclasses.Field]
_line_re = re.compile(r'''
^
(
[ \t](?P<cont>.*)
|
(?P<key>[^: \t\n\r\f\v]+)\s*:\s*(?P<value>.*)
)
$
''', re.VERBOSE)
def __init__(
self,
cls: type[_DataclassT],
ignore_unknown: bool,
) -> None:
self.reset()
self.cls = cls
self.fields = {}
self.ignore_unknown = True
for i in dataclasses.fields(cls):
if i.init and (deb822_field := i.metadata.get('deb822')):
self.fields[deb822_field.key] = i
def reset(self) -> None:
self.data = {}
self.current = None
def line(self, linenr: int, line: str) -> None:
m = self._line_re.match(line)
if not m:
raise Deb822DecodeError(
f'Not a header, not a continuation at line {linenr + 1}')
elif cont := m.group('cont'):
self.data[self.current] += '\n' + cont
elif deb822_key := m.group('key'):
field = self.fields.get(deb822_key)
if not field and not self.ignore_unknown:
raise Deb822DecodeError(
f'Unknown field "{deb822_key}" at line {linenr + 1}')
self.current = field
self.data[field] = m.group('value')
else:
raise NotImplementedError
def generate(self) -> _DataclassT | None:
if not self.data:
return None
r: dict[str, Any] = {}
for field, value in self.data.items():
field_factory: Optional[Callable[[str], Any]] = None
if field is None:
continue
elif (deb822_field := field.metadata.get('deb822')) and (load := deb822_field.load):
field_factory = load
elif isinstance(field.default_factory, type):
field_factory = field.default_factory
elif field.type in ('str', 'Optional[str]'):
field_factory = str
else:
raise RuntimeError(f'Unable to parse type {field.type}')
if field_factory is not None:
r[field.name] = field_factory(value)
self.reset()
return self.cls(**r)
def read_deb822(
cls: type[_DataclassT],
file: IO[str],
/,
ignore_unknown: bool = False,
) -> Iterable[_DataclassT]:
state = Deb822DecodeState(cls, ignore_unknown)
for linenr, line in enumerate(file):
line = line.rstrip('\n')
# Empty line, end of record
if line == '':
if (obj := state.generate()):
yield obj
# Strip comments rather than trying to preserve them
elif line[0] == '#':
continue
else:
state.line(linenr, line)
if (obj := state.generate()):
yield obj
def write_deb822(
objs: Iterable[_DataclassT],
file: IO[str],
/,
) -> None:
for obj in objs:
for field in dataclasses.fields(obj):
if (
(value := getattr(obj, field.name, None))
and (deb822_field := field.metadata.get('deb822'))
and (dump := deb822_field.dump) is not None
):
folded = '\n '.join(dump(value).strip().split('\n'))
file.write(f'{deb822_field.key}: {folded}\n')
file.write('\n')
|
