Re: [PATCH v13 1/3] grep: refactor next_match() and match_one_pattern() for external use

> These changes are made in preparation of, the colorization support for the
> "git log" subcommands that, rely on regex functionality (i.e. "--author",
> "--committer" and "--grep"). These changes are necessary primarily because
> match_one_pattern() expects header lines to be prefixed, however, in
> pretty, the prefixes are stripped from the lines because the name-email
> pairs need to go through additional parsing, before they can be printed and
> because next_match() doesn't handle the case of
> "ctx == GREP_CONTEXT_HEAD" at all. So, teach next_match() how to handle the
> new case and move match_one_pattern()'s core logic to
> headerless_match_one_pattern() while preserving match_one_pattern()'s uses
> that depend on the additional processing.
>
> Signed-off-by: Hamza Mahfooz <someguy@effective-light.com>
> ---
> v5: separate grep changes from pretty changes.
>
> v6: rescope some variables.
>
> v7: export header_field[] and allow for subsequent matches on header lines
>     in match_one_pattern().
>
> v8: add headerless_match_one_pattern() and move header_field[] back.
>
> v9: get rid of the new check in headerless_match_one_pattern(), move the
>     header pattern filtering logic in grep_next_match() and document
>     grep_next_match() in grep.h.
>
> v10: add a "magic" comment in grep_next_match() to signify a fall through
>      in the switch statement.