algo.py 文件源码

def _first_char(self, data):
        """Return the first character of data (in bibtex's sense)."""
        # XXX Should this be pulled out as some generic algorithm?
        pos = 0
        depths = self.__depth(data)
        while True:
            if pos == len(data):
                return ''
            elif data[pos].isalpha():
                return data[pos]
            elif data.startswith('{\\', pos):
                # Special character
                pos += 1
                m = re.compile(r'\\[a-zA-Z]+').match(data, pos)
                if m and m.group() in _CONTROL_SEQS:
                    # Known bibtex control sequence
                    return _CONTROL_SEQS[m.group()]
                # Scan for the first alphabetic character
                while pos < len(data) and depths[pos]:
                    if data[pos].isalpha():
                        return data[pos]
                    pos += 1
            elif data[pos] == '{':
                # Skip brace group
                while pos < len(data) and depths[pos]:
                    pos += 1
            else:
                pos += 1