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parser.py
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147 lines (118 loc) · 4.31 KB
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import codecs
import re
from typing import (IO, Iterator, Match, NamedTuple, Optional, Pattern, # noqa
Sequence, Text)
from .compat import to_text
def make_regex(string, extra_flags=0):
# type: (str, int) -> Pattern[Text]
return re.compile(to_text(string), re.UNICODE | extra_flags)
_whitespace = make_regex(r"\s*", extra_flags=re.MULTILINE)
_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]*=[^\S\r\n]*")
_single_quoted_value = make_regex(r"'((?:\\'|[^'])*)'")
_double_quoted_value = make_regex(r'"((?:\\"|[^"])*)"')
_unquoted_value_part = make_regex(r"([^ \r\n]*)")
_comment = make_regex(r"(?:\s*#[^\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"\\[\\']")
Binding = NamedTuple("Binding", [("key", Optional[Text]),
("value", Optional[Text]),
("original", Text)])
class Error(Exception):
pass
class Reader:
def __init__(self, stream):
# type: (IO[Text]) -> None
self.string = stream.read()
self.position = 0
self.mark = 0
def has_next(self):
# type: () -> bool
return self.position < len(self.string)
def set_mark(self):
# type: () -> None
self.mark = self.position
def get_marked(self):
# type: () -> Text
return self.string[self.mark:self.position]
def peek(self, count):
# type: (int) -> Text
return self.string[self.position:self.position + count]
def read(self, count):
# type: (int) -> Text
result = self.string[self.position:self.position + count]
if len(result) < count:
raise Error("read: End of string")
self.position += count
return result
def read_regex(self, regex):
# type: (Pattern[Text]) -> Sequence[Text]
match = regex.match(self.string, self.position)
if match is None:
raise Error("read_regex: Pattern not found")
self.position = match.end()
return match.groups()
def decode_escapes(regex, string):
# type: (Pattern[Text], Text) -> Text
def decode_match(match):
# type: (Match[Text]) -> Text
return codecs.decode(match.group(0), 'unicode-escape') # type: ignore
return regex.sub(decode_match, string)
def parse_key(reader):
# type: (Reader) -> Text
char = reader.peek(1)
if char == "'":
(key,) = reader.read_regex(_single_quoted_key)
else:
(key,) = reader.read_regex(_unquoted_key)
return key
def parse_unquoted_value(reader):
# type: (Reader) -> Text
value = u""
while True:
(part,) = reader.read_regex(_unquoted_value_part)
value += part
after = reader.peek(2)
if len(after) < 2 or after[0] in u"\r\n" or after[1] in u" #\r\n":
return value
value += reader.read(2)
def parse_value(reader):
# type: (Reader) -> Text
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):
# type: (Reader) -> Binding
reader.set_mark()
try:
reader.read_regex(_whitespace)
reader.read_regex(_export)
key = parse_key(reader)
reader.read_regex(_equal_sign)
value = parse_value(reader)
reader.read_regex(_comment)
reader.read_regex(_end_of_line)
return Binding(key=key, value=value, original=reader.get_marked())
except Error:
reader.read_regex(_rest_of_line)
return Binding(key=None, value=None, original=reader.get_marked())
def parse_stream(stream):
# type:(IO[Text]) -> Iterator[Binding]
reader = Reader(stream)
while reader.has_next():
try:
yield parse_binding(reader)
except Error:
return