Re: [PATCH v2 2/3] sequencer: factor out todo command name parsing

[Junio C Hamano <gitster@pobox.com>]

"Phillip Wood via GitGitGadget" <gitgitgadget@gmail.com> writes:

> As I don't want to burden other callers with having to pass in a pointer
> to the end of the line the test for an abbreviated command is
> changed.

A comma missing somewhere between "As <<REASON>>, <<CONSEQUENCE>>",
perhaps after "end of the line"?

> This change should not affect the behavior. Instead of testing
> `eol == bol + 1` the new code checks for the end of the line by testing
> for '\n', '\r' or '\0' following the abbreviated name. To avoid reading
> past the end of an empty string it also checks that there is actually a
> single character abbreviation before testing if it matches. This
> prevents it from matching '\0' as the abbreviated name and then trying
> to read another character.
>
> Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
> ---
>  sequencer.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/sequencer.c b/sequencer.c
> index 919e3153f5..793f86bf9a 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -2076,6 +2076,18 @@ const char *todo_item_get_arg(struct todo_list *todo_list,
>  	return todo_list->buf.buf + item->arg_offset;
>  }
>  
> +static int is_command(enum todo_command command, const char **bol)
> +{

This is a tangent, but the reason why the caller of this function is
named parse_insn_line() (and not parse_command_line()) is because a
"command" often refers "rebase", "cherry-pick" etc., and we need a
word to differenciate these from what is to be done as an individual
step.  Once the codebase stabilizes (read: I am excluding this kind
of change outside the scope of a series like this one), we'd need to
clean up the names in this file, I think.

> +	const char *str = todo_command_info[command].str;
> +	const char nick = todo_command_info[command].c;
> +	const char *p = *bol + 1;
> +
> +	return skip_prefix(*bol, str, bol) ||
> +		((nick && **bol == nick) &&

OK, making sure that nick is not NUL is the key to avoid stepping
past the NUL after the line that begins at *bol, as explained in the
additional paragraph in the proposed log message.

Looking good.

> +		 (*p == ' ' || *p == '\t' || *p == '\n' || *p == '\r' || !*p) &&
> +		 (*bol = p));
> +}
> +
>  static int parse_insn_line(struct repository *r, struct todo_item *item,
>  			   const char *buf, const char *bol, char *eol)
>  {
> @@ -2097,12 +2109,7 @@ static int parse_insn_line(struct repository *r, struct todo_item *item,
>  	}
>  
>  	for (i = 0; i < TODO_COMMENT; i++)
> -		if (skip_prefix(bol, todo_command_info[i].str, &bol)) {
> -			item->command = i;
> -			break;
> -		} else if ((bol + 1 == eol || bol[1] == ' ' || bol[1] == '\t') &&
> -			   *bol == todo_command_info[i].c) {
> -			bol++;
> +		if (is_command(i, &bol)) {
>  			item->command = i;
>  			break;
>  		}