re.py 文件源码

def _compile_repl(repl, pattern):
    # internal: compile replacement pattern
    try:
        return _cache_repl[repl, pattern]
    except KeyError:
        pass
    p = sre_parse.parse_template(repl, pattern)
    if len(_cache_repl) >= _MAXCACHE:
        _cache_repl.clear()
    _cache_repl[repl, pattern] = p
    return p