codekingpro/portable-devtools

1"""2    pygments.scanner3    ~~~~~~~~~~~~~~~~4 5    This library implements a regex based scanner. Some languages6    like Pascal are easy to parse but have some keywords that7    depend on the context. Because of this it's impossible to lex8    that just by using a regular expression lexer like the9    `RegexLexer`.10 11    Have a look at the `DelphiLexer` to get an idea of how to use12    this scanner.13 14    :copyright: Copyright 2006-present by the Pygments team, see AUTHORS.15    :license: BSD, see LICENSE for details.16"""17import re18 19 20class EndOfText(RuntimeError):21    """22    Raise if end of text is reached and the user23    tried to call a match function.24    """25 26 27class Scanner:28    """29    Simple scanner30 31    All method patterns are regular expression strings (not32    compiled expressions!)33    """34 35    def __init__(self, text, flags=0):36        """37        :param text:    The text which should be scanned38        :param flags:   default regular expression flags39        """40        self.data = text41        self.data_length = len(text)42        self.start_pos = 043        self.pos = 044        self.flags = flags45        self.last = None46        self.match = None47        self._re_cache = {}48 49    def eos(self):50        """`True` if the scanner reached the end of text."""51        return self.pos >= self.data_length52    eos = property(eos, eos.__doc__)53 54    def check(self, pattern):55        """56        Apply `pattern` on the current position and return57        the match object. (Doesn't touch pos). Use this for58        lookahead.59        """60        if self.eos:61            raise EndOfText()62        if pattern not in self._re_cache:63            self._re_cache[pattern] = re.compile(pattern, self.flags)64        return self._re_cache[pattern].match(self.data, self.pos)65 66    def test(self, pattern):67        """Apply a pattern on the current position and check68        if it patches. Doesn't touch pos.69        """70        return self.check(pattern) is not None71 72    def scan(self, pattern):73        """74        Scan the text for the given pattern and update pos/match75        and related fields. The return value is a boolean that76        indicates if the pattern matched. The matched value is77        stored on the instance as ``match``, the last value is78        stored as ``last``. ``start_pos`` is the position of the79        pointer before the pattern was matched, ``pos`` is the80        end position.81        """82        if self.eos:83            raise EndOfText()84        if pattern not in self._re_cache:85            self._re_cache[pattern] = re.compile(pattern, self.flags)86        self.last = self.match87        m = self._re_cache[pattern].match(self.data, self.pos)88        if m is None:89            return False90        self.start_pos = m.start()91        self.pos = m.end()92        self.match = m.group()93        return True94 95    def get_char(self):96        """Scan exactly one char."""97        self.scan('.')98 99    def __repr__(self):100        return '<%s %d/%d>' % (101            self.__class__.__name__,102            self.pos,103            self.data_length104        )105