Subject: Re: [PATCHv3 1/4] cache.h: document index_name_pos

From: Junio C Hamano <[email-masked]>
Date: Thu, 19 Jan 2017 12:17:51 -0800

Stefan Beller <[email-masked]> writes:

> Signed-off-by: Stefan Beller <[email-masked]>
> ---
>  cache.h | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/cache.h b/cache.h
> index 1b67f078dd..1469ddeafe 100644
> --- a/cache.h
> +++ b/cache.h
> @@ -575,7 +575,26 @@ extern int verify_path(const char *path);
>  extern int index_dir_exists(struct index_state *istate, const char *name, int namelen);
>  extern void adjust_dirname_case(struct index_state *istate, char *name);
>  extern struct cache_entry *index_file_exists(struct index_state *istate, const char *name, int namelen, int igncase);
> +
> +/*
> + * Searches for an entry defined by name and namelen in the given index.
> + * If the return value is positive (including 0) it is the position of an
> + * exact match. If the return value is negative, the negated value minus 1
> + * is the position where the entry would be inserted.

So if the return value is -3, you negate it to get 3 and then
subtract 1 to get 2.  The function is telling you that "e" will
sit at active_cache[2] in the following example.

Which is correct.

> + * Example: The current index consists of these files and its stages:
> + *
> + *   b#0, d#0, f#1, f#3
> + *
> + * index_name_pos(&index, "a", 1) -> -1
> + * index_name_pos(&index, "b", 1) ->  0
> + * index_name_pos(&index, "c", 1) -> -2
> + * index_name_pos(&index, "d", 1) ->  1
> + * index_name_pos(&index, "e", 1) -> -3
> + * index_name_pos(&index, "f", 1) -> -3
> + * index_name_pos(&index, "g", 1) -> -5
> + */

This time the counting seems correct.

Thanks.