lexer.py 文件源码

def compile_rules(environment):
    """Compiles all the rules from the environment into a list of rules."""
    e = re.escape
    rules = [
        (len(environment.comment_start_string), 'comment',
         e(environment.comment_start_string)),
        (len(environment.block_start_string), 'block',
         e(environment.block_start_string)),
        (len(environment.variable_start_string), 'variable',
         e(environment.variable_start_string))
    ]

    if environment.line_statement_prefix is not None:
        rules.append((len(environment.line_statement_prefix), 'linestatement',
                      r'^[ \t\v]*' + e(environment.line_statement_prefix)))
    if environment.line_comment_prefix is not None:
        rules.append((len(environment.line_comment_prefix), 'linecomment',
                      r'(?:^|(?<=\S))[^\S\r\n]*' +
                      e(environment.line_comment_prefix)))

    return [x[1:] for x in sorted(rules, reverse=True)]