_regex_core.py 文件源码

def compile_repl_group(source, pattern):
    "Compiles a replacement template group reference."
    source.expect("<")
    name = parse_name(source, True, True)

    source.expect(">")
    if name.isdigit():
        index = int(name)
        if not 0 <= index <= pattern.groups:
            raise error("invalid group reference", source.string, source.pos)

        return index

    try:
        return pattern.groupindex[name]
    except KeyError:
        raise IndexError("unknown group")

# The regular expression is parsed into a syntax tree. The different types of
# node are defined below.