You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
89 lines
2.3 KiB
89 lines
2.3 KiB
import re
|
|
from abc import ABCMeta
|
|
from typing import Iterator, Mapping, Optional, Pattern
|
|
|
|
_posix_variable = re.compile(
|
|
r"""
|
|
\$\{
|
|
(?P<name>[^\}:]*)
|
|
(?::-
|
|
(?P<default>[^\}]*)
|
|
)?
|
|
\}
|
|
""",
|
|
re.VERBOSE,
|
|
) # type: Pattern[str]
|
|
|
|
|
|
class Atom():
|
|
__metaclass__ = ABCMeta
|
|
|
|
def __ne__(self, other: object) -> bool:
|
|
result = self.__eq__(other)
|
|
if result is NotImplemented:
|
|
return NotImplemented
|
|
return not result
|
|
|
|
def resolve(self, env: Mapping[str, Optional[str]]) -> str:
|
|
raise NotImplementedError
|
|
|
|
|
|
class Literal(Atom):
|
|
def __init__(self, value: str) -> None:
|
|
self.value = value
|
|
|
|
def __repr__(self) -> str:
|
|
return "Literal(value={})".format(self.value)
|
|
|
|
def __eq__(self, other: object) -> bool:
|
|
if not isinstance(other, self.__class__):
|
|
return NotImplemented
|
|
return self.value == other.value
|
|
|
|
def __hash__(self) -> int:
|
|
return hash((self.__class__, self.value))
|
|
|
|
def resolve(self, env: Mapping[str, Optional[str]]) -> str:
|
|
return self.value
|
|
|
|
|
|
class Variable(Atom):
|
|
def __init__(self, name: str, default: Optional[str]) -> None:
|
|
self.name = name
|
|
self.default = default
|
|
|
|
def __repr__(self) -> str:
|
|
return "Variable(name={}, default={})".format(self.name, self.default)
|
|
|
|
def __eq__(self, other: object) -> bool:
|
|
if not isinstance(other, self.__class__):
|
|
return NotImplemented
|
|
return (self.name, self.default) == (other.name, other.default)
|
|
|
|
def __hash__(self) -> int:
|
|
return hash((self.__class__, self.name, self.default))
|
|
|
|
def resolve(self, env: Mapping[str, Optional[str]]) -> str:
|
|
default = self.default if self.default is not None else ""
|
|
result = env.get(self.name, default)
|
|
return result if result is not None else ""
|
|
|
|
|
|
def parse_variables(value: str) -> Iterator[Atom]:
|
|
cursor = 0
|
|
|
|
for match in _posix_variable.finditer(value):
|
|
(start, end) = match.span()
|
|
name = match.groupdict()["name"]
|
|
default = match.groupdict()["default"]
|
|
|
|
if start > cursor:
|
|
yield Literal(value=value[cursor:start])
|
|
|
|
yield Variable(name=name, default=default)
|
|
cursor = end
|
|
|
|
length = len(value)
|
|
if cursor < length:
|
|
yield Literal(value=value[cursor:length])
|