Viewing file:  parser.py (5.17 KB) -rw-r--r--
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import codecs
import re
from typing import (IO, Iterator, Match, NamedTuple, Optional, # noqa:F401
Pattern, Sequence, Tuple)
def make_regex(string: str, extra_flags: int = 0) -> Pattern[str]:
return re.compile(string, re.UNICODE | extra_flags)
_newline = make_regex(r"(\r\n|\n|\r)")
_multiline_whitespace = make_regex(r"\s*", extra_flags=re.MULTILINE)
_whitespace = make_regex(r"[^\S\r\n]*")
_export = make_regex(r"(?:export[^\S\r\n]+)?")
_single_quoted_key = make_regex(r"'([^']+)'")
_unquoted_key = make_regex(r"([^=\#\s]+)")
_equal_sign = make_regex(r"(=[^\S\r\n]*)")
_single_quoted_value = make_regex(r"'((?:\\'|[^'])*)'")
_double_quoted_value = make_regex(r'"((?:\\"|[^"])*)"')
_unquoted_value = make_regex(r"([^\r\n]*)")
_comment = make_regex(r"(?:[^\S\r\n]*#[^\r\n]*)?")
_end_of_line = make_regex(r"[^\S\r\n]*(?:\r\n|\n|\r|$)")
_rest_of_line = make_regex(r"[^\r\n]*(?:\r|\n|\r\n)?")
_double_quote_escapes = make_regex(r"\\[\\'\"abfnrtv]")
_single_quote_escapes = make_regex(r"\\[\\']")
Original = NamedTuple(
"Original",
[
("string", str),
("line", int),
],
)
Binding = NamedTuple(
"Binding",
[
("key", Optional[str]),
("value", Optional[str]),
("original", Original),
("error", bool),
],
)
class Position:
def __init__(self, chars: int, line: int) -> None:
self.chars = chars
self.line = line
@classmethod
def start(cls) -> "Position":
return cls(chars=0, line=1)
def set(self, other: "Position") -> None:
self.chars = other.chars
self.line = other.line
def advance(self, string: str) -> None:
self.chars += len(string)
self.line += len(re.findall(_newline, string))
class Error(Exception):
pass
class Reader:
def __init__(self, stream: IO[str]) -> None:
self.string = stream.read()
self.position = Position.start()
self.mark = Position.start()
def has_next(self) -> bool:
return self.position.chars < len(self.string)
def set_mark(self) -> None:
self.mark.set(self.position)
def get_marked(self) -> Original:
return Original(
string=self.string[self.mark.chars:self.position.chars],
line=self.mark.line,
)
def peek(self, count: int) -> str:
return self.string[self.position.chars:self.position.chars + count]
def read(self, count: int) -> str:
result = self.string[self.position.chars:self.position.chars + count]
if len(result) < count:
raise Error("read: End of string")
self.position.advance(result)
return result
def read_regex(self, regex: Pattern[str]) -> Sequence[str]:
match = regex.match(self.string, self.position.chars)
if match is None:
raise Error("read_regex: Pattern not found")
self.position.advance(self.string[match.start():match.end()])
return match.groups()
def decode_escapes(regex: Pattern[str], string: str) -> str:
def decode_match(match: Match[str]) -> str:
return codecs.decode(match.group(0), 'unicode-escape') # type: ignore
return regex.sub(decode_match, string)
def parse_key(reader: Reader) -> Optional[str]:
char = reader.peek(1)
if char == "#":
return None
elif char == "'":
(key,) = reader.read_regex(_single_quoted_key)
else:
(key,) = reader.read_regex(_unquoted_key)
return key
def parse_unquoted_value(reader: Reader) -> str:
(part,) = reader.read_regex(_unquoted_value)
return re.sub(r"\s+#.*", "", part).rstrip()
def parse_value(reader: Reader) -> str:
char = reader.peek(1)
if char == u"'":
(value,) = reader.read_regex(_single_quoted_value)
return decode_escapes(_single_quote_escapes, value)
elif char == u'"':
(value,) = reader.read_regex(_double_quoted_value)
return decode_escapes(_double_quote_escapes, value)
elif char in (u"", u"\n", u"\r"):
return u""
else:
return parse_unquoted_value(reader)
def parse_binding(reader: Reader) -> Binding:
reader.set_mark()
try:
reader.read_regex(_multiline_whitespace)
if not reader.has_next():
return Binding(
key=None,
value=None,
original=reader.get_marked(),
error=False,
)
reader.read_regex(_export)
key = parse_key(reader)
reader.read_regex(_whitespace)
if reader.peek(1) == "=":
reader.read_regex(_equal_sign)
value = parse_value(reader) # type: Optional[str]
else:
value = None
reader.read_regex(_comment)
reader.read_regex(_end_of_line)
return Binding(
key=key,
value=value,
original=reader.get_marked(),
error=False,
)
except Error:
reader.read_regex(_rest_of_line)
return Binding(
key=None,
value=None,
original=reader.get_marked(),
error=True,
)
def parse_stream(stream: IO[str]) -> Iterator[Binding]:
reader = Reader(stream)
while reader.has_next():
yield parse_binding(reader)
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