59 59 60 60
_default_localedir = os.path.join(sys.prefix, 'share', 'locale')
61 61 62 - 63 -
def test(condition, true, false):
64 -
"""
65 -
Implements the C expression:
66 - 67 -
condition ? true : false
68 - 69 -
Required to correctly interpret plural forms.
70 -
"""
71 -
if condition:
72 -
return true
62 +
# Expression parsing for plural form selection.
63 +
#
64 +
# The gettext library supports a small subset of C syntax. The only
65 +
# incompatible difference is that integer literals starting with zero are
66 +
# decimal.
67 +
#
68 +
# https://www.gnu.org/software/gettext/manual/gettext.html#Plural-forms
69 +
# http://git.savannah.gnu.org/cgit/gettext.git/tree/gettext-runtime/intl/plural.y
70 + 71 +
_token_pattern = re.compile(r"""
72 +
(?P<WHITESPACES>[ \t]+) | # spaces and horizontal tabs
73 +
(?P<NUMBER>[0-9]+\b) | # decimal integer
74 +
(?P<NAME>n\b) | # only n is allowed
75 +
(?P<PARENTHESIS>[()]) |
76 +
(?P<OPERATOR>[-*/%+?:]|[><!]=?|==|&&|\|\|) | # !, *, /, %, +, -, <, >,
77 +
# <=, >=, ==, !=, &&, ||,
78 +
# ? :
79 +
# unary and bitwise ops
80 +
# not allowed
81 +
(?P<INVALID>\w+|.) # invalid token
82 +
""", re.VERBOSE|re.DOTALL)
83 + 84 +
def _tokenize(plural):
85 +
for mo in re.finditer(_token_pattern, plural):
86 +
kind = mo.lastgroup
87 +
if kind == 'WHITESPACES':
88 +
continue
89 +
value = mo.group(kind)
90 +
if kind == 'INVALID':
91 +
raise ValueError('invalid token in plural form: %s' % value)
92 +
yield value
93 +
yield ''
94 + 95 +
def _error(value):
96 +
if value:
97 +
return ValueError('unexpected token in plural form: %s' % value)
73 98
else:
74 -
return false
75 - 99 +
return ValueError('unexpected end of plural form')
100 + 101 +
_binary_ops = (
102 +
('||',),
103 +
('&&',),
104 +
('==', '!='),
105 +
('<', '>', '<=', '>='),
106 +
('+', '-'),
107 +
('*', '/', '%'),
108 +
)
109 +
_binary_ops = {op: i for i, ops in enumerate(_binary_ops, 1) for op in ops}
110 +
_c2py_ops = {'||': 'or', '&&': 'and', '/': '//'}
111 + 112 +
def _parse(tokens, priority=-1):
113 +
result = ''
114 +
nexttok = next(tokens)
115 +
while nexttok == '!':
116 +
result += 'not '
117 +
nexttok = next(tokens)
118 + 119 +
if nexttok == '(':
120 +
sub, nexttok = _parse(tokens)
121 +
result = '%s(%s)' % (result, sub)
122 +
if nexttok != ')':
123 +
raise ValueError('unbalanced parenthesis in plural form')
124 +
elif nexttok == 'n':
125 +
result = '%s%s' % (result, nexttok)
126 +
else:
127 +
try:
128 +
value = int(nexttok, 10)
129 +
except ValueError:
130 +
raise _error(nexttok)
131 +
result = '%s%d' % (result, value)
132 +
nexttok = next(tokens)
133 + 134 +
j = 100
135 +
while nexttok in _binary_ops:
136 +
i = _binary_ops[nexttok]
137 +
if i < priority:
138 +
break
139 +
# Break chained comparisons
140 +
if i in (3, 4) and j in (3, 4): # '==', '!=', '<', '>', '<=', '>='
141 +
result = '(%s)' % result
142 +
# Replace some C operators by their Python equivalents
143 +
op = _c2py_ops.get(nexttok, nexttok)
144 +
right, nexttok = _parse(tokens, i + 1)
145 +
result = '%s %s %s' % (result, op, right)
146 +
j = i
147 +
if j == priority == 4: # '<', '>', '<=', '>='
148 +
result = '(%s)' % result
149 + 150 +
if nexttok == '?' and priority <= 0:
151 +
if_true, nexttok = _parse(tokens, 0)
152 +
if nexttok != ':':
153 +
raise _error(nexttok)
154 +
if_false, nexttok = _parse(tokens)
155 +
result = '%s if %s else %s' % (if_true, result, if_false)
156 +
if priority == 0:
157 +
result = '(%s)' % result
158 + 159 +
return result, nexttok
76 160 77 161
def c2py(plural):
78 162
"""Gets a C expression as used in PO files for plural forms and returns a
79 -
Python lambda function that implements an equivalent expression.
163 +
Python function that implements an equivalent expression.
80 164
"""
81 -
# Security check, allow only the "n" identifier
82 -
try:
83 -
from cStringIO import StringIO
84 -
except ImportError:
85 -
from StringIO import StringIO
86 -
import token, tokenize
87 -
tokens = tokenize.generate_tokens(StringIO(plural).readline)
88 -
try:
89 -
danger = [x for x in tokens if x[0] == token.NAME and x[1] != 'n']
90 -
except tokenize.TokenError:
91 -
raise ValueError, \
92 -
'plural forms expression error, maybe unbalanced parenthesis'
93 -
else:
94 -
if danger:
95 -
raise ValueError, 'plural forms expression could be dangerous'
96 - 97 -
# Replace some C operators by their Python equivalents
98 -
plural = plural.replace('&&', ' and ')
99 -
plural = plural.replace('||', ' or ')
100 - 101 -
expr = re.compile(r'\!([^=])')
102 -
plural = expr.sub(' not \\1', plural)
103 - 104 -
# Regular expression and replacement function used to transform
105 -
# "a?b:c" to "test(a,b,c)".
106 -
expr = re.compile(r'(.*?)\?(.*?):(.*)')
107 -
def repl(x):
108 -
return "test(%s, %s, %s)" % (x.group(1), x.group(2),
109 -
expr.sub(repl, x.group(3)))
110 - 111 -
# Code to transform the plural expression, taking care of parentheses
112 -
stack = ['']
113 -
for c in plural:
114 -
if c == '(':
115 -
stack.append('')
116 -
elif c == ')':
117 -
if len(stack) == 1:
118 -
# Actually, we never reach this code, because unbalanced
119 -
# parentheses get caught in the security check at the
120 -
# beginning.
121 -
raise ValueError, 'unbalanced parenthesis in plural form'
122 -
s = expr.sub(repl, stack.pop())
123 -
stack[-1] += '(%s)' % s
124 -
else:
125 -
stack[-1] += c
126 -
plural = expr.sub(repl, stack.pop())
127 - 128 -
return eval('lambda n: int(%s)' % plural)
129 165 166 +
if len(plural) > 1000:
167 +
raise ValueError('plural form expression is too long')
168 +
try:
169 +
result, nexttok = _parse(_tokenize(plural))
170 +
if nexttok:
171 +
raise _error(nexttok)
172 + 173 +
depth = 0
174 +
for c in result:
175 +
if c == '(':
176 +
depth += 1
177 +
if depth > 20:
178 +
# Python compiler limit is about 90.
179 +
# The most complex example has 2.
180 +
raise ValueError('plural form expression is too complex')
181 +
elif c == ')':
182 +
depth -= 1
183 + 184 +
ns = {}
185 +
exec('''if 1:
186 +
def func(n):
187 +
if not isinstance(n, int):
188 +
raise ValueError('Plural value must be an integer.')
189 +
return int(%s)
190 +
''' % result, ns)
191 +
return ns['func']
192 +
except RuntimeError:
193 +
# Recursion error can be raised in _parse() or exec().
194 +
raise ValueError('plural form expression is too complex')
130 195 131 196 132 197
def _expand_lang(locale):
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