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
|
from __future__ import absolute_import
from __future__ import print_function
from __future__ import unicode_literals
import sys
import logging
from warnings import warn
import six
from scss.ast import Literal
from scss.cssdefs import _expr_glob_re, _interpolate_re
from scss.errors import SassError, SassEvaluationError, SassParseError
from scss.grammar.expression import SassExpression, SassExpressionScanner
from scss.rule import Namespace
from scss.types import String
from scss.types import Value
from scss.util import dequote
log = logging.getLogger(__name__)
class Calculator(object):
"""Expression evaluator."""
ast_cache = {}
def __init__(
self, namespace=None,
ignore_parse_errors=False,
undefined_variables_fatal=True,
):
if namespace is None:
self.namespace = Namespace()
else:
self.namespace = namespace
self.ignore_parse_errors = ignore_parse_errors
self.undefined_variables_fatal = undefined_variables_fatal
def _pound_substitute(self, result):
expr = result.group(1)
value = self.evaluate_expression(expr)
if value is None:
return self.apply_vars(expr)
elif value.is_null:
return ""
else:
return dequote(value.render())
def do_glob_math(self, cont):
"""Performs #{}-interpolation. The result is always treated as a fixed
syntactic unit and will not be re-evaluated.
"""
# TODO that's a lie! this should be in the parser for most cases.
if not isinstance(cont, six.string_types):
warn(FutureWarning(
"do_glob_math was passed a non-string {0!r} "
"-- this will no longer be supported in pyScss 2.0"
.format(cont)
))
cont = six.text_type(cont)
if '#{' not in cont:
return cont
cont = _expr_glob_re.sub(self._pound_substitute, cont)
return cont
def apply_vars(self, cont):
# TODO this is very complicated. it should go away once everything
# valid is actually parseable.
if isinstance(cont, six.string_types) and '$' in cont:
try:
# Optimization: the full cont is a variable in the context,
cont = self.namespace.variable(cont)
except KeyError:
# Interpolate variables:
def _av(m):
v = None
n = m.group(2)
try:
v = self.namespace.variable(n)
except KeyError:
if self.undefined_variables_fatal:
raise SyntaxError("Undefined variable: '%s'." % n)
else:
log.error("Undefined variable '%s'", n, extra={'stack': True})
return n
else:
if v:
if not isinstance(v, Value):
raise TypeError(
"Somehow got a variable {0!r} "
"with a non-Sass value: {1!r}"
.format(n, v)
)
v = v.render()
# TODO this used to test for _dequote
if m.group(1):
v = dequote(v)
else:
v = m.group(0)
return v
cont = _interpolate_re.sub(_av, cont)
else:
# Variable succeeded, so we need to render it
cont = cont.render()
# TODO this is surprising and shouldn't be here
cont = self.do_glob_math(cont)
return cont
def calculate(self, expression, divide=False):
result = self.evaluate_expression(expression, divide=divide)
if result is None:
return String.unquoted(self.apply_vars(expression))
return result
# TODO only used by magic-import...?
def interpolate(self, var):
value = self.namespace.variable(var)
if var != value and isinstance(value, six.string_types):
_vi = self.evaluate_expression(value)
if _vi is not None:
value = _vi
return value
def evaluate_expression(self, expr, divide=False):
try:
ast = self.parse_expression(expr)
except SassError as e:
if self.ignore_parse_errors:
return None
raise
try:
return ast.evaluate(self, divide=divide)
except Exception as e:
six.reraise(SassEvaluationError, SassEvaluationError(e, expression=expr), sys.exc_info()[2])
def parse_expression(self, expr, target='goal'):
if isinstance(expr, six.text_type):
# OK
pass
elif isinstance(expr, six.binary_type):
# Dubious
warn(FutureWarning(
"parse_expression was passed binary data {0!r} "
"-- this will no longer be supported in pyScss 2.0"
.format(expr)
))
# Don't guess an encoding; you reap what you sow
expr = six.text_type(expr)
else:
raise TypeError("Expected string, got %r" % (expr,))
key = (target, expr)
if key in self.ast_cache:
return self.ast_cache[key]
try:
parser = SassExpression(SassExpressionScanner(expr))
ast = getattr(parser, target)()
except SyntaxError as e:
raise SassParseError(e, expression=expr, expression_pos=parser._char_pos)
self.ast_cache[key] = ast
return ast
def parse_interpolations(self, string):
"""Parse a string for interpolations, but don't treat anything else as
Sass syntax. Returns an AST node.
"""
# Shortcut: if there are no #s in the string in the first place, it
# must not have any interpolations, right?
if '#' not in string:
return Literal(String.unquoted(string))
return self.parse_expression(string, 'goal_interpolated_literal')
def parse_vars_and_interpolations(self, string):
"""Parse a string for variables and interpolations, but don't treat
anything else as Sass syntax. Returns an AST node.
"""
# Shortcut: if there are no #s or $s in the string in the first place,
# it must not have anything of interest.
if '#' not in string and '$' not in string:
return Literal(String.unquoted(string))
return self.parse_expression(
string, 'goal_interpolated_literal_with_vars')
__all__ = ('Calculator',)
|
