Re: [PATCH 03/18] branch-diff: first rudimentary implementation

> At this stage, `git branch-diff` can determine corresponding commits of
> two related commit ranges. This makes use of the recently introduced
> implementation of the Hungarian algorithm.
>
> The core of this patch is a straight port of the ideas of tbdiff, the
> seemingly dormant project at https://github.com/trast/tbdiff.
>
> The output does not at all match `tbdiff`'s output yet, as this patch
> really concentrates on getting the patch matching part right.
>
> Note: due to differences in the diff algorithm (`tbdiff` uses the
> Pythong module `difflib`, Git uses its xdiff fork), the cost matrix

> calculated by `branch-diff` is different (but very similar) to the one
> calculated by `tbdiff`. Therefore, it is possible that they find
> different matching commits in corner cases (e.g. when a patch was split
> into two patches of roughly equal length).
>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
> diff --git a/builtin/branch-diff.c b/builtin/branch-diff.c
> @@ -19,6 +23,279 @@ static int parse_creation_weight(const struct option *opt, const char *arg,
> +static int read_patches(const char *range, struct string_list *list)
> +{
> +       [...]
> +       struct strbuf buf = STRBUF_INIT, line = STRBUF_INIT;
> +       [...]
> +                       } else if (starts_with(line.buf, "    ")) {
> +                               strbuf_addbuf(&buf, &line);
> +                               strbuf_addch(&buf, '\n');
> +                       }
> +
> +                       continue;

> +               } else if (starts_with(line.buf, "@@ "))
> +                       strbuf_addstr(&buf, "@@");
> +               [...]
> +       }
> +       fclose(in);
> +
> +       if (util)
> +               string_list_append(list, buf.buf)->util = util;
> +       strbuf_release(&buf);

> +       if (finish_command(&cp))
> +               return -1;
> +
> +       return 0;
> +}
> @@ -32,9 +309,63 @@ int cmd_branch_diff(int argc, const char **argv, const char *prefix)
> +       if (argc == 2) {
> +               if (!strstr(argv[0], ".."))
> +                       warning(_("no .. in range: '%s'"), argv[0]);
> +               strbuf_addstr(&range1, argv[0]);
> +
> +               if (!strstr(argv[1], ".."))
> +                       warning(_("no .. in range: '%s'"), argv[1]);
> +               strbuf_addstr(&range2, argv[1]);
> +       } else if (argc == 1) {
> +               if (!b)
> +                       die(_("single arg format requires a symmetric range"));
> +       } else {
> +               error("Need two commit ranges");

> +               usage_with_options(builtin_branch_diff_usage, options);
> +       }
> +
> +       if (read_patches(range1.buf, &branch1))
> +               res = error(_("could not parse log for '%s'"), range1.buf);
> +       if (!res && read_patches(range2.buf, &branch2))
> +               res = error(_("could not parse log for '%s'"), range2.buf);