"Elijah Newren via GitGitGadget" <gitgitgadget@xxxxxxxxx> writes:
> +MAYBE_UNUSED
> +static int find_basename_matches(struct diff_options *options,
> + int minimum_score,
> + int num_src)
> +{
> + int i;
> + struct strintmap sources;
> + struct strintmap dests;
> +
> + /* Create maps of basename -> fullname(s) for sources and dests */
> + strintmap_init_with_options(&sources, -1, NULL, 0);
> + strintmap_init_with_options(&dests, -1, NULL, 0);
> + for (i = 0; i < num_src; ++i) {
> + char *filename = rename_src[i].p->one->path;
> + const char *base;
> +
> + /* exact renames removed in remove_unneeded_paths_from_src() */
> + assert(!rename_src[i].p->one->rename_used);
> +
> + /* Record index within rename_src (i) if basename is unique */
> + base = get_basename(filename);
> + if (strintmap_contains(&sources, base))
> + strintmap_set(&sources, base, -1);
> + else
> + strintmap_set(&sources, base, i);
> + }
> + for (i = 0; i < rename_dst_nr; ++i) {
> + char *filename = rename_dst[i].p->two->path;
> + const char *base;
> +
> + if (rename_dst[i].is_rename)
> + continue; /* involved in exact match already. */
> +
> + /* Record index within rename_dst (i) if basename is unique */
> + base = get_basename(filename);
> + if (strintmap_contains(&dests, base))
> + strintmap_set(&dests, base, -1);
> + else
> + strintmap_set(&dests, base, i);
> + }
> +
> + /* TODO: Make use of basenames source and destination basenames */
;-)
So at this point sources and dests can be used to quickly look up,
given a filename, if there is a single src among all sources, and a
single dst among all dests, that have the filename.
I wonder if the second loop over destinations can be "optimized"
further by using the sources map, though. The reason you quash
entries with -1 when you see second instance of the same name is
because you intend to limit the heuristics only to a uniquely named
file among the removed files going to a uniquely named file among
the added files, right? So even if a name is unique among dests,
if that name has duplicates on the source side, there is no point
recording its location. i.e.
/* record index within dst if it is unique in both dst and src */
base = get_basename(filename);
if (strintmap_contains(&sources, base) ||
strintmap_contains(&dests, base))
strintmap_set(&dests, base, -1);
else
strintmap_set(&dests, base, i);
perhaps?
I guess it depends on what actually will be written in this "TODO"
space how effective such a change would be. Presumably, you'd
iterate over &sources while skipping entries that record -1, to
learn (basename, i), and use the basename found there to consult
&dests to see if it yields a non-negative integer j, to notice that
rename_src[i] is a good candidate to match rename_dst[j]. If that
is the case, then such a change won't help as an optimization at
all, as we'd need to consult &dests map with the basename anyway,
so let's scratch the above idea.
In any case, after we walk over rename_src[] and rename_dst[] once,
the number of entries in &sources would be smaller than rename_src[]
so iterating over &sources, hunting for entries that record
non-negative index into rename_src[] would hopefully be cheaper than
the naive loop we've been working with. I like the idea of using the
strintmap for this part of the code.
Thanks.
> + strintmap_clear(&sources);
> + strintmap_clear(&dests);
> +
> + return 0;
> +}
> +
> #define NUM_CANDIDATE_PER_DST 4
> static void record_if_better(struct diff_score m[], struct diff_score *o)
> {
