Changes to std::match_results and <regex>

[Stephen M. Webb]

Quoting Jonathan Wakely <jwakely.gcc@gmail.com>:
> [...]
> My suggested implementation is documented in the code:
>
>       The vector base is empty if this does not represent a successful match.
>       Otherwise it contains n+3 elements where n is the number of marked
>       sub-expressions:
>       [0]   entire match
>       [1]   1st marked subexpression
>       ...
>       [n]   nth marked subexpression
>       [n+1] prefix
>       [n+2] suffix
>
> This means size() == n+1 == (N ? N-2 : 0)
> Copying, moving and swapping, as well as empty(), are now simply
> forwarded to the vector base.
>
> I made position() return -1 for out-of-range, consistent with
> boost::regex (and with e.g. string::find)
>
> operator[] checks its argument and returns a static object
> representing an unmatched subexpression (as required).
>
> Does anyone have any objections or improvements to this change?

I like this.  Do you have test cases?

-- 
Stephen M. Webb