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"""Pure-Python scanner and parser, used if _speedups is not available."""
from scss.cssdefs import SEPARATOR
import re
DEBUG = False
# TODO copied from __init__
_nl_num_re = re.compile(r'\n.+' + SEPARATOR, re.MULTILINE)
_blocks_re = re.compile(r'[{},;()\'"\n]')
def _strip_selprop(selprop, lineno):
# Get the line number of the selector or property and strip all other
# line numbers that might still be there (from multiline selectors)
_lineno, _sep, selprop = selprop.partition(SEPARATOR)
if _sep == SEPARATOR:
_lineno = _lineno.strip(' \t\n;')
try:
lineno = int(_lineno)
except ValueError:
pass
else:
selprop = _lineno
selprop = _nl_num_re.sub('\n', selprop)
selprop = selprop.strip()
return selprop, lineno
def _strip(selprop):
# Strip all line numbers, ignoring them in the way
selprop, _ = _strip_selprop(selprop, None)
return selprop
def locate_blocks(codestr):
"""
For processing CSS like strings.
Either returns all selectors (that can be "smart" multi-lined, as
long as it's joined by `,`, or enclosed in `(` and `)`) with its code block
(the one between `{` and `}`, which can be nested), or the "lose" code
(properties) that doesn't have any blocks.
"""
lineno = 0
par = 0
instr = None
depth = 0
skip = False
thin = None
i = init = safe = lose = 0
start = end = None
for m in _blocks_re.finditer(codestr):
i = m.start(0)
c = codestr[i]
if instr is not None:
if c == instr:
instr = None # A string ends (FIXME: needs to accept escaped characters)
elif c in ('"', "'"):
instr = c # A string starts
elif c == '(': # parenthesis begins:
par += 1
thin = None
safe = i + 1
elif c == ')': # parenthesis ends:
par -= 1
elif not par and not instr:
if c == '{': # block begins:
if depth == 0:
if i > 0 and codestr[i - 1] == '#': # Do not process #{...} as blocks!
skip = True
else:
start = i
if thin is not None and _strip(codestr[thin:i]):
init = thin
if lose < init:
_property, lineno = _strip_selprop(codestr[lose:init], lineno)
if _property:
yield lineno, _property, None
lose = init
thin = None
depth += 1
elif c == '}': # block ends:
if depth > 0:
depth -= 1
if depth == 0:
if not skip:
end = i
_selectors, lineno = _strip_selprop(codestr[init:start], lineno)
_codestr = codestr[start + 1:end].strip()
if _selectors:
yield lineno, _selectors, _codestr
init = safe = lose = end + 1
thin = None
skip = False
elif depth == 0:
if c == ';': # End of property (or block):
init = i
if lose < init:
_property, lineno = _strip_selprop(codestr[lose:init], lineno)
if _property:
yield lineno, _property, None
init = safe = lose = i + 1
thin = None
elif c == ',':
if thin is not None and _strip(codestr[thin:i]):
init = thin
thin = None
safe = i + 1
elif c == '\n':
if thin is not None and _strip(codestr[thin:i]):
init = thin
thin = i + 1
elif thin is None and _strip(codestr[safe:i]):
thin = i + 1 # Step on thin ice, if it breaks, it breaks here
if depth > 0:
if not skip:
_selectors, lineno = _strip_selprop(codestr[init:start], lineno)
_codestr = codestr[start + 1:].strip()
if _selectors:
yield lineno, _selectors, _codestr
if par:
raise Exception("Missing closing parenthesis somewhere in block: '%s'" % _selectors)
elif instr:
raise Exception("Missing closing string somewhere in block: '%s'" % _selectors)
else:
raise Exception("Block never closed: '%s'" % _selectors)
losestr = codestr[lose:]
for _property in losestr.split(';'):
_property, lineno = _strip_selprop(_property, lineno)
if _property:
yield lineno, _property, None
################################################################################
# Parser
DEBUG = False
class NoMoreTokens(Exception):
"""
Another exception object, for when we run out of tokens
"""
pass
class Scanner(object):
def __init__(self, patterns, ignore, input=None):
"""
Patterns is [(terminal,regex)...]
Ignore is [terminal,...];
Input is a string
"""
self.reset(input)
self.ignore = ignore
# The stored patterns are a pair (compiled regex,source
# regex). If the patterns variable passed in to the
# constructor is None, we assume that the class already has a
# proper .patterns list constructed
if patterns is not None:
self.patterns = []
for k, r in patterns:
self.patterns.append((k, re.compile(r)))
def reset(self, input):
self.tokens = []
self.restrictions = []
self.input = input
self.pos = 0
def __repr__(self):
"""
Print the last 10 tokens that have been scanned in
"""
output = ''
for t in self.tokens[-10:]:
output = "%s\n (@%s) %s = %s" % (output, t[0], t[2], repr(t[3]))
return output
def _scan(self, restrict, context=None):
"""
Should scan another token and add it to the list, self.tokens,
and add the restriction to self.restrictions
"""
# Keep looking for a token, ignoring any in self.ignore
while True:
tok = None
# Search the patterns for a match, with earlier
# tokens in the list having preference
best_match = -1
best_pat = None
for tok, regex in self.patterns:
if DEBUG:
print("\tTrying %s: %s at pos %d -> %s" % (repr(tok), repr(regex.pattern), self.pos, repr(self.input)))
# First check to see if we're restricting to this token
if restrict and tok not in restrict and tok not in self.ignore:
if DEBUG:
print "\tSkipping %s!" % repr(tok)
continue
m = regex.match(self.input, self.pos)
if m and m.end() - m.start() > best_match:
# We got a match that's better than the previous one
best_pat = tok
best_match = m.end() - m.start()
if DEBUG:
print("Match OK! %s: %s at pos %d" % (repr(tok), repr(regex.pattern), self.pos))
break
# If we didn't find anything, raise an error
if best_pat is None or best_match < 0:
msg = "Bad token: %s" % ("???" if tok is None else repr(tok),)
if restrict:
msg = "%s found while trying to find one of the restricted tokens: %s" % ("???" if tok is None else repr(tok), ", ".join(repr(r) for r in restrict))
raise SyntaxError("SyntaxError[@ char %s: %s]" % (repr(self.pos), msg), context=context)
# If we found something that isn't to be ignored, return it
if best_pat in self.ignore:
# This token should be ignored...
self.pos += best_match
else:
end_pos = self.pos + best_match
# Create a token with this data
token = (
self.pos,
end_pos,
best_pat,
self.input[self.pos:end_pos]
)
self.pos = end_pos
# Only add this token if it's not in the list
# (to prevent looping)
if not self.tokens or token != self.tokens[-1]:
self.tokens.append(token)
self.restrictions.append(restrict)
return 1
return 0
def token(self, i, restrict=None, **kwargs):
"""
Get the i'th token, and if i is one past the end, then scan
for another token; restrict is a list of tokens that
are allowed, or 0 for any token.
"""
context = kwargs.get("context")
tokens_len = len(self.tokens)
if i == tokens_len: # We are at the end, get the next...
tokens_len += self._scan(restrict, context)
elif i >= 0 and i < tokens_len:
if restrict and self.restrictions[i] and restrict > self.restrictions[i]:
raise NotImplementedError("Unimplemented: restriction set changed")
if i >= 0 and i < tokens_len:
return self.tokens[i]
raise NoMoreTokens
def rewind(self, i):
tokens_len = len(self.tokens)
if i <= tokens_len:
token = self.tokens[i]
self.tokens = self.tokens[:i]
self.restrictions = self.restrictions[:i]
self.pos = token[0]
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