def match(pattern, string, flags=0):
    """Try to apply the pattern at the start of the string, returning
    a match object, or None if no match was found."""
    return _compile(pattern, flags).match(string)

def search(pattern, string, flags=0):
    """Scan through string looking for a match to the pattern, returning
    a match object, or None if no match was found."""
    return _compile(pattern, flags).search(string)

class Scanner:
    def __init__(self, lexicon, flags=0):
        from sre_constants import BRANCH, SUBPATTERN
        self.lexicon = lexicon
        # combine phrases into a compound pattern
        p = []
        s = sre_parse.Pattern()
        s.flags = flags
        for phrase, action in lexicon:
            p.append(sre_parse.SubPattern(s, [
                (SUBPATTERN, (len(p)+1, sre_parse.parse(phrase, flags))),
                ]))
        s.groups = len(p)+1
        p = sre_parse.SubPattern(s, [(BRANCH, (None, p))])
        self.scanner = sre_compile.compile(p)
    def scan(self, string):
        result = []
        append = result.append
        match = self.scanner.scanner(string).match
        i = 0
        while 1:
            m = match()
            if not m:
                break
            j = m.end()
            if i == j:
                break
            action = self.lexicon[m.lastindex-1][1]
            if hasattr(action, '__call__'):
                self.match = m
                action = action(self, m.group())
            if action is not None:
                append(action)
            i = j
        return result, string[i:]