Re: [PATCH v9 02/11] ref-filter: introduce ref_formatting_state

[Eric Sunshine <sunshine@sunshineco.com>]

On Tue, Aug 4, 2015 at 8:42 AM, Karthik Nayak <karthik.188@gmail.com> wrote:
> Introduce a ref_formatting_state which will eventually hold the values
> of modifier atoms. Implement this within ref-filter.
>
> Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
> ---
> +static void apply_formatting_state(struct ref_formatting_state *state, struct strbuf *final)
> +{
> +       /* More formatting options to be evetually added */
> +       strbuf_addbuf(final, state->output);
> +       strbuf_release(state->output);

I guess the idea here is that you intend state->output to be re-used
and it is convenient to "clear" it here rather than making that the
responsibility of each caller. For re-use, it is more typical to use
strbuf_reset() than strbuf_release() (though Junio may disagree[1]).

[1]: http://article.gmane.org/gmane.comp.version-control.git/273094

> +}
> +
>  void show_ref_array_item(struct ref_array_item *info, const char *format, int quote_style)
>  {
>         const char *cp, *sp, *ep;
> -       struct strbuf output = STRBUF_INIT;
> +       struct strbuf value = STRBUF_INIT;
> +       struct strbuf final_buf = STRBUF_INIT;
> +       struct ref_formatting_state state;
>         int i;
>
> +       memset(&state, 0, sizeof(state));
> +       state.quote_style = quote_style;
> +       state.output = &value;

It feels strange to assign a local variable reference to state.output,
and there's no obvious reason why you should need to do so. I would
have instead expected ref_format_state to be declared as:

    struct ref_formatting_state {
       int quote_style;
       struct strbuf output;
    };

and initialized as so:

    memset(&state, 0, sizeof(state));
    state.quote_style = quote_style;
    strbuf_init(&state.output, 0);

(In fact, the memset() isn't even necessary here since you're
initializing all fields explicitly, though perhaps you want the
memset() because a future patch adds more fields which are not
initialized explicitly?)

This still allows re-use via strbuf_reset() mentioned above.

And, of course, you'd want to strbuf_release() it at the end of this
function where you're already releasing final_buf.

>         for (cp = format; *cp && (sp = find_next(cp)); cp = ep + 1) {
> -               struct atom_value *atomv;
> +               struct atom_value *atomv = NULL;

What is this change about?

>                 ep = strchr(sp, ')');
> -               if (cp < sp)
> -                       emit(cp, sp, &output);
> +               if (cp < sp) {
> +                       emit(cp, sp, &state);
> +                       apply_formatting_state(&state, &final_buf);
> +               }
>                 get_ref_atom_value(info, parse_ref_filter_atom(sp + 2, ep), &atomv);
> -               print_value(atomv, quote_style, &output);
> +               process_formatting_state(atomv, &state);
> +               print_value(atomv, &state);
> +               apply_formatting_state(&state, &final_buf);
>         }
>         if (*cp) {
>                 sp = cp + strlen(cp);
> -               emit(cp, sp, &output);
> +               emit(cp, sp, &state);
> +               apply_formatting_state(&state, &final_buf);

I'm getting the feeling that these functions
(process_formatting_state, print_value, emit, apply_formatting_state)
are becoming misnamed (again) with the latest structural changes (but
perhaps I haven't read far enough into the series yet?).

process_formatting_state() is rather generic.

print_value() and emit() both imply outputting something, but neither
does so anymore.

apply_formatting_state() seems to be more about finalizing the
already-formatted output.