[Patch 1/2] Rewrite regex scanner

[Jonathan Wakely]

On 23 August 2013 10:15, Tim Shen  wrote:
> These two patches are not logically relative, but the next patch is
> based on this one.
>
> This patch of the regex scanner(or lexer) supports all styles
> specified by N3376. It shall build an abstract layer of regex token
> sequence, so that, ideally, the parser and executor do not need to
> care which style they are handling.
>
> Originally _Scanner is a class in regex_compiler.{h,tcc}. Since it
> could be a standlone module, I move it to regex_scanner.{h,tcc}.
>
> I try my best to reduce duplicated code and make the logic
> clear(_M_escape_map and _M_spec_char help a lot). However, I'm still
> worrying about potential unexpected behaviors, because it's not about
> correctness, but about reading standards.
>
> More testcases are welcome!
>
> Thanks!
>
> PS: For personal reasons, I probably cannot make a response in several
> days, but I'll try my best ;)

If this bootstraps and passes tests then it's OK.

I would rearrange the ChangeLog, to put

        * include/bits/regex_executor.tcc: Don't use reference for submatch.

after regex_scanner.tcc, so that the files the _Scanner is moved from
come immediately before the files it is moved to, otherwise it reads
like "move _Scanner from ... don't use reference ... here" which
doesn't make much sense :-)

Thanks.