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bbc2Saurabh Kumar
bbc2
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Saurabh Kumar
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Refactor parser to fix inconsistencies (theskumar#180)
* Move parser to separate module * Add tests * Use unicode strings for unit tests in Python 2 Using `str` (e.g. `bytes`) is inconsistent with the types and the implementation. * Refactor parser This fixes inconsistencies reported after the release of version 0.10.0: * Valid escapes were interpreted as control characters even when in single-quoted strings. * `#` was interpreted as the start of a comment even if there was no whitespace preceding it. However, we are keeping the interpretation of escapes in double-quoted strings as they didn't make sense in versions before 0.10.0. The single large regular expression is replaced with a handwritten top-down parser using smaller regular expressions. The reason for this change is that it would have been very difficult or impossible to satisfy the parsing requirements with a single regex.
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‎README.md‎

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@@ -299,8 +299,9 @@ Changelog
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Unreleased
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-----
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- ...
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- Refactor parser to fix parsing inconsistencies ([@bbc2])([#170]).
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- Interpret escapes as control characters only in double-quoted strings.
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- Interpret `#` as start of comment only if preceded by whitespace.
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0.10.2
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-----
@@ -428,6 +429,7 @@ Unreleased
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[#172]: https://github.com/theskumar/python-dotenv/issues/172
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[#121]: https://github.com/theskumar/python-dotenv/issues/121
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[#176]: https://github.com/theskumar/python-dotenv/issues/176
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[#170]: https://github.com/theskumar/python-dotenv/issues/170
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[@asyncee]: https://github.com/asyncee
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[@greyli]: https://github.com/greyli

‎setup.cfg‎

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@@ -5,6 +5,9 @@ universal = 1
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max-line-length = 120
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exclude = .tox,.git,docs,venv,.venv
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[mypy]
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ignore_missing_imports = true
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[metadata]
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description-file = README.rst
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‎src/dotenv/compat.py‎

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@@ -1,8 +1,23 @@
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import sys
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from typing import Text
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if sys.version_info >= (3, 0):
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from io import StringIO # noqa
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else:
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from StringIO import StringIO # noqa
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PY2 = sys.version_info[0] == 2 # type: bool
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def to_text(string):
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# type: (str) -> Text
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"""
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Make a string Unicode if it isn't already.
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This is useful for defining raw unicode strings because `ur"foo"` isn't valid in
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Python 3.
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"""
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if PY2:
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return string.decode("utf-8")
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else:
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return string

‎src/dotenv/main.py‎

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@@ -1,21 +1,21 @@
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# -*- coding: utf-8 -*-
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from __future__ import absolute_import, print_function, unicode_literals
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4-
import codecs
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import io
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import os
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import re
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import shutil
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import sys
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from subprocess import Popen
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import tempfile
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from typing import (Any, Dict, Iterator, List, Match, NamedTuple, Optional, # noqa
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Pattern, Union, TYPE_CHECKING, Text, IO, Tuple) # noqa
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from typing import (Dict, Iterator, List, Match, Optional, # noqa
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Pattern, Union, TYPE_CHECKING, Text, IO, Tuple)
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import warnings
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from collections import OrderedDict
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from contextlib import contextmanager
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from .compat import StringIO, PY2
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from .parser import parse_stream
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if TYPE_CHECKING: # pragma: no cover
2121
if sys.version_info >= (3, 6):
@@ -30,84 +30,6 @@
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__posix_variable = re.compile(r'\$\{[^\}]*\}') # type: Pattern[Text]
3232

33-
_binding = re.compile(
34-
r"""
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(
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\s* # leading whitespace
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(?:export{0}+)? # export
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( '[^']+' # single-quoted key
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| [^=\#\s]+ # or unquoted key
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)?
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(?:
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(?:{0}*={0}*) # equal sign
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( '(?:\\'|[^'])*' # single-quoted value
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| "(?:\\"|[^"])*" # or double-quoted value
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| [^\#\r\n]* # or unquoted value
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)
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)?
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\s* # trailing whitespace
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(?:\#[^\r\n]*)? # comment
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(?:\r|\n|\r\n)? # newline
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)
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""".format(r'[^\S\r\n]'),
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re.MULTILINE | re.VERBOSE,
58-
) # type: Pattern[Text]
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_escape_sequence = re.compile(r"\\[\\'\"abfnrtv]") # type: Pattern[Text]
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Binding = NamedTuple("Binding", [("key", Optional[Text]),
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("value", Optional[Text]),
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("original", Text)])
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def decode_escapes(string):
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# type: (Text) -> Text
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def decode_match(match):
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# type: (Match[Text]) -> Text
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return codecs.decode(match.group(0), 'unicode-escape') # type: ignore
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return _escape_sequence.sub(decode_match, string)
75-
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def is_surrounded_by(string, char):
78-
# type: (Text, Text) -> bool
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return (
80-
len(string) > 1
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and string[0] == string[-1] == char
82-
)
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84-
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def parse_binding(string, position):
86-
# type: (Text, int) -> Tuple[Binding, int]
87-
match = _binding.match(string, position)
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assert match is not None
89-
(matched, key, value) = match.groups()
90-
if key is None or value is None:
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key = None
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value = None
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else:
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value_quoted = is_surrounded_by(value, "'") or is_surrounded_by(value, '"')
95-
if value_quoted:
96-
value = decode_escapes(value[1:-1])
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else:
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value = value.strip()
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return (Binding(key=key, value=value, original=matched), match.end())
100-
101-
102-
def parse_stream(stream):
103-
# type:(IO[Text]) -> Iterator[Binding]
104-
string = stream.read()
105-
position = 0
106-
length = len(string)
107-
while position < length:
108-
(binding, position) = parse_binding(string, position)
109-
yield binding
110-
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11234
def to_env(text):
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# type: (Text) -> str

‎src/dotenv/parser.py‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,147 @@
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import codecs
2+
import re
3+
from typing import (IO, Iterator, Match, NamedTuple, Optional, Pattern, # noqa
4+
Sequence, Text)
5+
6+
from .compat import to_text
7+
8+
9+
def make_regex(string, extra_flags=0):
10+
# type: (str, int) -> Pattern[Text]
11+
return re.compile(to_text(string), re.UNICODE | extra_flags)
12+
13+
14+
_whitespace = make_regex(r"\s*", extra_flags=re.MULTILINE)
15+
_export = make_regex(r"(?:export[^\S\r\n]+)?")
16+
_single_quoted_key = make_regex(r"'([^']+)'")
17+
_unquoted_key = make_regex(r"([^=\#\s]+)")
18+
_equal_sign = make_regex(r"[^\S\r\n]*=[^\S\r\n]*")
19+
_single_quoted_value = make_regex(r"'((?:\\'|[^'])*)'")
20+
_double_quoted_value = make_regex(r'"((?:\\"|[^"])*)"')
21+
_unquoted_value_part = make_regex(r"([^ \r\n]*)")
22+
_comment = make_regex(r"(?:\s*#[^\r\n]*)?")
23+
_end_of_line = make_regex(r"[^\S\r\n]*(?:\r\n|\n|\r)?")
24+
_rest_of_line = make_regex(r"[^\r\n]*(?:\r|\n|\r\n)?")
25+
_double_quote_escapes = make_regex(r"\\[\\'\"abfnrtv]")
26+
_single_quote_escapes = make_regex(r"\\[\\']")
27+
28+
Binding = NamedTuple("Binding", [("key", Optional[Text]),
29+
("value", Optional[Text]),
30+
("original", Text)])
31+
32+
33+
class Error(Exception):
34+
pass
35+
36+
37+
class Reader:
38+
def __init__(self, stream):
39+
# type: (IO[Text]) -> None
40+
self.string = stream.read()
41+
self.position = 0
42+
self.mark = 0
43+
44+
def has_next(self):
45+
# type: () -> bool
46+
return self.position < len(self.string)
47+
48+
def set_mark(self):
49+
# type: () -> None
50+
self.mark = self.position
51+
52+
def get_marked(self):
53+
# type: () -> Text
54+
return self.string[self.mark:self.position]
55+
56+
def peek(self, count):
57+
# type: (int) -> Text
58+
return self.string[self.position:self.position + count]
59+
60+
def read(self, count):
61+
# type: (int) -> Text
62+
result = self.string[self.position:self.position + count]
63+
if len(result) < count:
64+
raise Error("read: End of string")
65+
self.position += count
66+
return result
67+
68+
def read_regex(self, regex):
69+
# type: (Pattern[Text]) -> Sequence[Text]
70+
match = regex.match(self.string, self.position)
71+
if match is None:
72+
raise Error("read_regex: Pattern not found")
73+
self.position = match.end()
74+
return match.groups()
75+
76+
77+
def decode_escapes(regex, string):
78+
# type: (Pattern[Text], Text) -> Text
79+
def decode_match(match):
80+
# type: (Match[Text]) -> Text
81+
return codecs.decode(match.group(0), 'unicode-escape') # type: ignore
82+
83+
return regex.sub(decode_match, string)
84+
85+
86+
def parse_key(reader):
87+
# type: (Reader) -> Text
88+
char = reader.peek(1)
89+
if char == "'":
90+
(key,) = reader.read_regex(_single_quoted_key)
91+
else:
92+
(key,) = reader.read_regex(_unquoted_key)
93+
return key
94+
95+
96+
def parse_unquoted_value(reader):
97+
# type: (Reader) -> Text
98+
value = u""
99+
while True:
100+
(part,) = reader.read_regex(_unquoted_value_part)
101+
value += part
102+
after = reader.peek(2)
103+
if len(after) < 2 or after[0] in u"\r\n" or after[1] in u" #\r\n":
104+
return value
105+
value += reader.read(2)
106+
107+
108+
def parse_value(reader):
109+
# type: (Reader) -> Text
110+
char = reader.peek(1)
111+
if char == u"'":
112+
(value,) = reader.read_regex(_single_quoted_value)
113+
return decode_escapes(_single_quote_escapes, value)
114+
elif char == u'"':
115+
(value,) = reader.read_regex(_double_quoted_value)
116+
return decode_escapes(_double_quote_escapes, value)
117+
elif char in (u"", u"\n", u"\r"):
118+
return u""
119+
else:
120+
return parse_unquoted_value(reader)
121+
122+
123+
def parse_binding(reader):
124+
# type: (Reader) -> Binding
125+
reader.set_mark()
126+
try:
127+
reader.read_regex(_whitespace)
128+
reader.read_regex(_export)
129+
key = parse_key(reader)
130+
reader.read_regex(_equal_sign)
131+
value = parse_value(reader)
132+
reader.read_regex(_comment)
133+
reader.read_regex(_end_of_line)
134+
return Binding(key=key, value=value, original=reader.get_marked())
135+
except Error:
136+
reader.read_regex(_rest_of_line)
137+
return Binding(key=None, value=None, original=reader.get_marked())
138+
139+
140+
def parse_stream(stream):
141+
# type:(IO[Text]) -> Iterator[Binding]
142+
reader = Reader(stream)
143+
while reader.has_next():
144+
try:
145+
yield parse_binding(reader)
146+
except Error:
147+
return

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