def dis()

in Lib/sre_compile.py [0:0]


def dis(code):
    import sys

    labels = set()
    level = 0
    offset_width = len(str(len(code) - 1))

    def dis_(start, end):
        def print_(*args, to=None):
            if to is not None:
                labels.add(to)
                args += ('(to %d)' % (to,),)
            print('%*d%s ' % (offset_width, start, ':' if start in labels else '.'),
                  end='  '*(level-1))
            print(*args)

        def print_2(*args):
            print(end=' '*(offset_width + 2*level))
            print(*args)

        nonlocal level
        level += 1
        i = start
        while i < end:
            start = i
            op = code[i]
            i += 1
            op = OPCODES[op]
            if op in (SUCCESS, FAILURE, ANY, ANY_ALL,
                      MAX_UNTIL, MIN_UNTIL, NEGATE):
                print_(op)
            elif op in (LITERAL, NOT_LITERAL,
                        LITERAL_IGNORE, NOT_LITERAL_IGNORE,
                        LITERAL_UNI_IGNORE, NOT_LITERAL_UNI_IGNORE,
                        LITERAL_LOC_IGNORE, NOT_LITERAL_LOC_IGNORE):
                arg = code[i]
                i += 1
                print_(op, '%#02x (%r)' % (arg, chr(arg)))
            elif op is AT:
                arg = code[i]
                i += 1
                arg = str(ATCODES[arg])
                assert arg[:3] == 'AT_'
                print_(op, arg[3:])
            elif op is CATEGORY:
                arg = code[i]
                i += 1
                arg = str(CHCODES[arg])
                assert arg[:9] == 'CATEGORY_'
                print_(op, arg[9:])
            elif op in (IN, IN_IGNORE, IN_UNI_IGNORE, IN_LOC_IGNORE):
                skip = code[i]
                print_(op, skip, to=i+skip)
                dis_(i+1, i+skip)
                i += skip
            elif op in (RANGE, RANGE_UNI_IGNORE):
                lo, hi = code[i: i+2]
                i += 2
                print_(op, '%#02x %#02x (%r-%r)' % (lo, hi, chr(lo), chr(hi)))
            elif op is CHARSET:
                print_(op, _hex_code(code[i: i + 256//_CODEBITS]))
                i += 256//_CODEBITS
            elif op is BIGCHARSET:
                arg = code[i]
                i += 1
                mapping = list(b''.join(x.to_bytes(_sre.CODESIZE, sys.byteorder)
                                        for x in code[i: i + 256//_sre.CODESIZE]))
                print_(op, arg, mapping)
                i += 256//_sre.CODESIZE
                level += 1
                for j in range(arg):
                    print_2(_hex_code(code[i: i + 256//_CODEBITS]))
                    i += 256//_CODEBITS
                level -= 1
            elif op in (MARK, GROUPREF, GROUPREF_IGNORE, GROUPREF_UNI_IGNORE,
                        GROUPREF_LOC_IGNORE):
                arg = code[i]
                i += 1
                print_(op, arg)
            elif op is JUMP:
                skip = code[i]
                print_(op, skip, to=i+skip)
                i += 1
            elif op is BRANCH:
                skip = code[i]
                print_(op, skip, to=i+skip)
                while skip:
                    dis_(i+1, i+skip)
                    i += skip
                    start = i
                    skip = code[i]
                    if skip:
                        print_('branch', skip, to=i+skip)
                    else:
                        print_(FAILURE)
                i += 1
            elif op in (REPEAT, REPEAT_ONE, MIN_REPEAT_ONE):
                skip, min, max = code[i: i+3]
                if max == MAXREPEAT:
                    max = 'MAXREPEAT'
                print_(op, skip, min, max, to=i+skip)
                dis_(i+3, i+skip)
                i += skip
            elif op is GROUPREF_EXISTS:
                arg, skip = code[i: i+2]
                print_(op, arg, skip, to=i+skip)
                i += 2
            elif op in (ASSERT, ASSERT_NOT):
                skip, arg = code[i: i+2]
                print_(op, skip, arg, to=i+skip)
                dis_(i+2, i+skip)
                i += skip
            elif op is INFO:
                skip, flags, min, max = code[i: i+4]
                if max == MAXREPEAT:
                    max = 'MAXREPEAT'
                print_(op, skip, bin(flags), min, max, to=i+skip)
                start = i+4
                if flags & SRE_INFO_PREFIX:
                    prefix_len, prefix_skip = code[i+4: i+6]
                    print_2('  prefix_skip', prefix_skip)
                    start = i + 6
                    prefix = code[start: start+prefix_len]
                    print_2('  prefix',
                            '[%s]' % ', '.join('%#02x' % x for x in prefix),
                            '(%r)' % ''.join(map(chr, prefix)))
                    start += prefix_len
                    print_2('  overlap', code[start: start+prefix_len])
                    start += prefix_len
                if flags & SRE_INFO_CHARSET:
                    level += 1
                    print_2('in')
                    dis_(start, i+skip)
                    level -= 1
                i += skip
            else:
                raise ValueError(op)

        level -= 1

    dis_(0, len(code))