Re: [RFA] C++-ify parse_format_string

[Simon Marchi <simark@simark.ca>]

On 2017-11-23 05:40 PM, Pedro Alves wrote:
> On 11/23/2017 09:13 PM, Simon Marchi wrote:
> 
>> I have a patch in some branch that does essentially the same thing, so
>> I was able to compare our approaches.  In my version, I removed the
>> big allocation that is shared among pieces, and made each piece have
>> its own std::string.  Unless we want to keep the current allocation
>> scheme for performance/memory usage reasons, I think that using
>> std::strings simplifies things in the parse_format_string function.
>> The format_pieces structure is replaced with an std::vector of
>> format_piece.
> 
> Sounds like a step backwards to me.  If it simplifies things, then
> it sounds like it might be because we're missing some utility,
> like string_view or something like that.

I am not sure I understand, can you expand a little bit about what you
have in mind?

What I meant is that is changes things like this:

	    strncpy (current_substring, percent_loc, length_before_ll);
	    strcpy (current_substring + length_before_ll, "I64");
	    current_substring[length_before_ll + 3] =
	      percent_loc[length_before_ll + lcount];
	    current_substring += length_before_ll + 4;

into this

	    piece_string.assign (percent_loc, length_before_ll);
	    piece_string += "I64";
	    piece_string += percent_loc[length_before_ll + lcount];

Less magical number, less playing with offsets, etc.

Simon