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# coding: utf8
"""
tinycss.parsing
---------------
Utilities for parsing lists of tokens.
:copyright: (c) 2012 by Simon Sapin.
:license: BSD, see LICENSE for more details.
"""
from __future__ import unicode_literals
# TODO: unit tests
def split_on_comma(tokens):
"""Split a list of tokens on commas, ie ``,`` DELIM tokens.
Only "top-level" comma tokens are splitting points, not commas inside a
function or other :class:`ContainerToken`.
:param tokens:
An iterable of :class:`~.token_data.Token` or
:class:`~.token_data.ContainerToken`.
:returns:
A list of lists of tokens
"""
parts = []
this_part = []
for token in tokens:
if token.type == 'DELIM' and token.value == ',':
parts.append(this_part)
this_part = []
else:
this_part.append(token)
parts.append(this_part)
return parts
def strip_whitespace(tokens):
"""Remove whitespace at the beggining and end of a token list.
Whitespace tokens in-between other tokens in the list are preserved.
:param tokens:
A list of :class:`~.token_data.Token` or
:class:`~.token_data.ContainerToken`.
:return:
A new sub-sequence of the list.
"""
for i, token in enumerate(tokens):
if token.type != 'S':
break
else:
return [] # only whitespace
tokens = tokens[i:]
while tokens and tokens[-1].type == 'S':
tokens.pop()
return tokens
def remove_whitespace(tokens):
"""Remove any top-level whitespace in a token list.
Whitespace tokens inside recursive :class:`~.token_data.ContainerToken`
are preserved.
:param tokens:
A list of :class:`~.token_data.Token` or
:class:`~.token_data.ContainerToken`.
:return:
A new sub-sequence of the list.
"""
return [token for token in tokens if token.type != 'S']
def validate_value(tokens):
"""Validate a property value.
:param tokens:
an iterable of tokens
:raises:
:class:`ParseError` if there is any invalid token for the 'value'
production of the core grammar.
"""
for token in tokens:
type_ = token.type
if type_ == '{':
validate_block(token.content, 'property value')
else:
validate_any(token, 'property value')
def validate_block(tokens, context):
"""
:raises:
:class:`ParseError` if there is any invalid token for the 'block'
production of the core grammar.
:param tokens: an iterable of tokens
:param context: a string for the 'unexpected in ...' message
"""
for token in tokens:
type_ = token.type
if type_ == '{':
validate_block(token.content, context)
elif type_ not in (';', 'ATKEYWORD'):
validate_any(token, context)
def validate_any(token, context):
"""
:raises:
:class:`ParseError` if this is an invalid token for the
'any' production of the core grammar.
:param token: a single token
:param context: a string for the 'unexpected in ...' message
"""
type_ = token.type
if type_ in ('FUNCTION', '(', '['):
for token in token.content:
validate_any(token, type_)
elif type_ not in ('S', 'IDENT', 'DIMENSION', 'PERCENTAGE', 'NUMBER',
'INTEGER', 'URI', 'DELIM', 'STRING', 'HASH', ':',
'UNICODE-RANGE'):
if type_ in ('}', ')', ']'):
adjective = 'unmatched'
else:
adjective = 'unexpected'
raise ParseError(token,
'{0} {1} token in {2}'.format(adjective, type_, context))
class ParseError(ValueError):
"""Details about a CSS syntax error. Usually indicates that something
(a rule or a declaration) was ignored and will not appear as a parsed
object.
This exception is typically logged in a list rather than being propagated
to the user API.
.. attribute:: line
Source line where the error occured.
.. attribute:: column
Column in the source line where the error occured.
.. attribute:: reason
What happend (a string).
"""
def __init__(self, subject, reason):
self.line = subject.line
self.column = subject.column
self.reason = reason
super(ParseError, self).__init__(
'Parse error at {0.line}:{0.column}, {0.reason}'.format(self))
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