-
Notifications
You must be signed in to change notification settings - Fork 240
/
_parser.py
228 lines (189 loc) · 6.49 KB
/
_parser.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
# The docstring for each parse function contains the grammar for the rule.
# The grammar uses a simple EBNF-inspired syntax:
#
# - Uppercase names are tokens
# - Lowercase names are rules (parsed with a parse_* function)
# - Parentheses are used for grouping
# - A | means either-or
# - A * means 0 or more
# - A + means 1 or more
# - A ? means 0 or 1
from ast import literal_eval
from typing import Any, List, NamedTuple, Tuple, Union
from ._tokenizer import Tokenizer
class Node:
def __init__(self, value: str) -> None:
self.value = value
def __str__(self) -> str:
return self.value
def __repr__(self) -> str:
return f"<{self.__class__.__name__}('{self}')>"
def serialize(self) -> str:
raise NotImplementedError
class Variable(Node):
def serialize(self) -> str:
return str(self)
class Value(Node):
def serialize(self) -> str:
return f'"{self}"'
class Op(Node):
def serialize(self) -> str:
return str(self)
MarkerVar = Union[Variable, Value]
MarkerItem = Tuple[MarkerVar, Op, MarkerVar]
# MarkerAtom = Union[MarkerItem, List["MarkerAtom"]]
# MarkerList = List[Union["MarkerList", MarkerAtom, str]]
# mypy does not suport recursive type definition
# https://github.com/python/mypy/issues/731
MarkerAtom = Any
MarkerList = List[Any]
class Requirement(NamedTuple):
name: str
url: str
extras: List[str]
specifier: str
marker: str
def parse_named_requirement(requirement: str) -> Requirement:
"""
named_requirement:
IDENTIFIER extras (URL_SPEC | specifier) (SEMICOLON marker_expr)? END
"""
tokens = Tokenizer(requirement)
tokens.expect("IDENTIFIER", error_message="Expression must begin with package name")
name = tokens.read("IDENTIFIER").text
extras = parse_extras(tokens)
specifier = ""
url = ""
if tokens.match("URL_SPEC"):
url = tokens.read().text[1:].strip()
elif not tokens.match("END"):
specifier = parse_specifier(tokens)
if tokens.try_read("SEMICOLON"):
marker = ""
while not tokens.match("END"):
# we don't validate markers here, it's done later as part of
# packaging/requirements.py
marker += tokens.read().text
else:
marker = ""
tokens.expect(
"END",
error_message="Expected semicolon (followed by markers) or end of string",
)
return Requirement(name, url, extras, specifier, marker)
def parse_extras(tokens: Tokenizer) -> List[str]:
"""
extras: LBRACKET (IDENTIFIER (COMMA IDENTIFIER)*)? RBRACKET
"""
extras = []
if tokens.try_read("LBRACKET"):
while tokens.match("IDENTIFIER"):
extras.append(tokens.read("IDENTIFIER").text)
if not tokens.match("RBRACKET"):
tokens.read("COMMA", error_message="Missing comma after extra")
if not tokens.match("COMMA") and tokens.match("RBRACKET"):
break
tokens.read("RBRACKET", error_message="Closing square bracket is missing")
return extras
def parse_specifier(tokens: Tokenizer) -> str:
"""
specifier:
LPAREN version_many? RPAREN | version_many
"""
lparen = False
if tokens.try_read("LPAREN"):
lparen = True
parsed_specifiers = parse_version_many(tokens)
if lparen and not tokens.try_read("RPAREN"):
tokens.raise_syntax_error(message="Closing right parenthesis is missing")
return parsed_specifiers
def parse_version_many(tokens: Tokenizer) -> str:
"""
version_many: OP VERSION (COMMA OP VERSION)*
"""
parsed_specifiers = ""
while tokens.match("OP"):
parsed_specifiers += tokens.read("OP").text
if tokens.match("VERSION"):
parsed_specifiers += tokens.read("VERSION").text
else:
tokens.raise_syntax_error(message="Missing version")
if not tokens.match("COMMA"):
break
tokens.expect("COMMA", error_message="Missing comma after version")
parsed_specifiers += tokens.read("COMMA").text
return parsed_specifiers
def parse_marker_expr(tokens: Tokenizer) -> MarkerList:
"""
marker_expr: MARKER_ATOM (BOOLOP + MARKER_ATOM)+
"""
expression = [parse_marker_atom(tokens)]
while tokens.match("BOOLOP"):
tok = tokens.read("BOOLOP")
expr_right = parse_marker_atom(tokens)
expression.extend((tok.text, expr_right))
return expression
def parse_marker_atom(tokens: Tokenizer) -> MarkerAtom:
"""
marker_atom: LPAREN marker_expr RPAREN | marker_item
"""
if tokens.try_read("LPAREN"):
marker = parse_marker_expr(tokens)
tokens.read("RPAREN", error_message="Closing right parenthesis is missing")
return marker
else:
return parse_marker_item(tokens)
def parse_marker_item(tokens: Tokenizer) -> MarkerItem:
"""
marker_item: marker_var marker_op marker_var
"""
marker_var_left = parse_marker_var(tokens)
marker_op = parse_marker_op(tokens)
marker_var_right = parse_marker_var(tokens)
return (marker_var_left, marker_op, marker_var_right)
def parse_marker_var(tokens: Tokenizer) -> MarkerVar:
"""
marker_var: env_var | python_str
"""
if tokens.match("VARIABLE"):
return parse_env_var(tokens)
else:
return parse_python_str(tokens)
def parse_env_var(tokens: Tokenizer) -> Variable:
"""
env_var: VARIABLE
"""
env_var = tokens.read("VARIABLE").text.replace(".", "_")
if (
env_var == "platform_python_implementation"
or env_var == "python_implementation"
):
return Variable("platform_python_implementation")
else:
return Variable(env_var)
def parse_python_str(tokens: Tokenizer) -> Value:
"""
python_str: QUOTED_STRING
"""
token = tokens.read(
"QUOTED_STRING",
error_message="String with single or double quote at the beginning is expected",
).text
python_str = literal_eval(token)
return Value(str(python_str))
def parse_marker_op(tokens: Tokenizer) -> Op:
"""
marker_op: IN | NOT IN | OP
"""
if tokens.try_read("IN"):
return Op("in")
elif tokens.try_read("NOT"):
tokens.read("IN", error_message="NOT token must be follewed by IN token")
return Op("not in")
elif tokens.match("OP"):
return Op(tokens.read().text)
else:
return tokens.raise_syntax_error(
message='Couldn\'t parse marker operator. Expecting one of \
"<=, <, !=, ==, >=, >, ~=, ===, not, not in"'
)