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 Python 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@xxxxxx> --- builtin/branch-diff.c | 335 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 334 insertions(+), 1 deletion(-) diff --git a/builtin/branch-diff.c b/builtin/branch-diff.c index 60a4b4fbe30..c462681067c 100644 --- a/builtin/branch-diff.c +++ b/builtin/branch-diff.c @@ -1,6 +1,12 @@ #include "cache.h" #include "builtin.h" #include "parse-options.h" +#include "string-list.h" +#include "run-command.h" +#include "argv-array.h" +#include "hashmap.h" +#include "xdiff-interface.h" +#include "hungarian.h" static const char * const builtin_branch_diff_usage[] = { N_("git branch-diff [<options>] <old-base>..<old-tip> <new-base>..<new-tip>"), @@ -20,6 +26,279 @@ static int parse_creation_weight(const struct option *opt, const char *arg, return 0; } +struct patch_util { + /* For the search for an exact match */ + struct hashmap_entry e; + const char *diff, *patch; + + int i; + int diffsize; + size_t diff_offset; + /* the index of the matching item in the other branch, or -1 */ + int matching; + struct object_id oid; +}; + +/* + * Reads the patches into a string list, with the `util` field being populated + * as struct object_id (will need to be free()d). + */ +static int read_patches(const char *range, struct string_list *list) +{ + struct child_process cp = CHILD_PROCESS_INIT; + FILE *in; + struct strbuf buf = STRBUF_INIT, line = STRBUF_INIT; + struct patch_util *util = NULL; + int in_header = 1; + + argv_array_pushl(&cp.args, "log", "--no-color", "-p", "--no-merges", + "--reverse", "--date-order", "--decorate=no", + "--no-abbrev-commit", range, + NULL); + cp.out = -1; + cp.no_stdin = 1; + cp.git_cmd = 1; + + if (start_command(&cp)) + return error_errno(_("could not start `log`")); + in = fdopen(cp.out, "r"); + if (!in) { + error_errno(_("could not read `log` output")); + finish_command(&cp); + return -1; + } + + while (strbuf_getline(&line, in) != EOF) { + const char *p; + + if (skip_prefix(line.buf, "commit ", &p)) { + if (util) { + string_list_append(list, buf.buf)->util = util; + strbuf_reset(&buf); + } + util = xcalloc(sizeof(*util), 1); + if (get_oid(p, &util->oid)) { + error(_("could not parse commit '%s'"), p); + free(util); + string_list_clear(list, 1); + strbuf_release(&buf); + strbuf_release(&line); + fclose(in); + finish_command(&cp); + return -1; + } + util->matching = -1; + in_header = 1; + continue; + } + + if (starts_with(line.buf, "diff --git")) { + in_header = 0; + strbuf_addch(&buf, '\n'); + if (!util->diff_offset) + util->diff_offset = buf.len; + strbuf_addbuf(&buf, &line); + } else if (in_header) { + if (starts_with(line.buf, "Author: ")) { + strbuf_addbuf(&buf, &line); + strbuf_addstr(&buf, "\n\n"); + } else if (starts_with(line.buf, " ")) { + strbuf_addbuf(&buf, &line); + strbuf_addch(&buf, '\n'); + } + continue; + } else if (starts_with(line.buf, "@@ ")) + strbuf_addstr(&buf, "@@"); + else if (line.buf[0] && !starts_with(line.buf, "index ")) + /* + * A completely blank (not ' \n', which is context) + * line is not valid in a diff. We skip it + * silently, because this neatly handles the blank + * separator line between commits in git-log + * output. + */ + strbuf_addbuf(&buf, &line); + else + continue; + + strbuf_addch(&buf, '\n'); + util->diffsize++; + } + fclose(in); + strbuf_release(&line); + + if (util) + string_list_append(list, buf.buf)->util = util; + strbuf_release(&buf); + + if (finish_command(&cp)) + return -1; + + return 0; +} + +static int patch_util_cmp(const void *dummy, const struct patch_util *a, + const struct patch_util *b, const char *keydata) +{ + return strcmp(a->diff, keydata ? keydata : b->diff); +} + +static void find_exact_matches(struct string_list *a, struct string_list *b) +{ + struct hashmap map; + int i; + + hashmap_init(&map, (hashmap_cmp_fn)patch_util_cmp, NULL, 0); + + /* First, add the patches of a to a hash map */ + for (i = 0; i < a->nr; i++) { + struct patch_util *util = a->items[i].util; + + util->i = i; + util->patch = a->items[i].string; + util->diff = util->patch + util->diff_offset; + hashmap_entry_init(util, strhash(util->diff)); + hashmap_add(&map, util); + } + + /* Now try to find exact matches in b */ + for (i = 0; i < b->nr; i++) { + struct patch_util *util = b->items[i].util, *other; + + util->i = i; + util->patch = b->items[i].string; + util->diff = util->patch + util->diff_offset; + hashmap_entry_init(util, strhash(util->diff)); + other = hashmap_remove(&map, util, NULL); + if (other) { + if (other->matching >= 0) + BUG("already assigned!"); + + other->matching = i; + util->matching = other->i; + } + } + + hashmap_free(&map, 0); +} + +static void diffsize_consume(void *data, char *line, unsigned long len) +{ + (*(int *)data)++; +} + +static int diffsize(const char *a, const char *b) +{ + xpparam_t pp = { 0 }; + xdemitconf_t cfg = { 0 }; + mmfile_t mf1, mf2; + int count = 0; + + mf1.ptr = (char *)a; + mf1.size = strlen(a); + mf2.ptr = (char *)b; + mf2.size = strlen(b); + + cfg.ctxlen = 3; + if (!xdi_diff_outf(&mf1, &mf2, diffsize_consume, &count, &pp, &cfg)) + return count; + + error(_("failed to generate diff")); + return INT_MAX; +} + +static int get_correspondences(struct string_list *a, struct string_list *b, + double creation_weight) +{ + int n = a->nr + b->nr; + double *cost = xmalloc(sizeof(double) * n * n), c; + int *a2b = xmalloc(sizeof(int) * n), *b2a = xmalloc(sizeof(int) * n); + int i, j, res; + + for (i = 0; i < a->nr; i++) { + struct patch_util *a_util = a->items[i].util; + + for (j = 0; j < b->nr; j++) { + struct patch_util *b_util = b->items[j].util; + + if (a_util->matching == j) + c = 0; + else if (a_util->matching < 0 && b_util->matching < 0) + c = diffsize(a_util->diff, b_util->diff); + else + c = INT_MAX; + cost[i + n * j] = c; + } + + c = a_util->matching < 0 ? + a_util->diffsize * creation_weight : INT_MAX; + for (j = b->nr; j < n; j++) + cost[i + n * j] = c; + } + + for (j = 0; j < b->nr; j++) { + struct patch_util *util = b->items[j].util; + + c = util->matching < 0 ? + util->diffsize * creation_weight : INT_MAX; + for (i = a->nr; i < n; i++) + cost[i + n * j] = c; + } + + for (i = a->nr; i < n; i++) + for (j = b->nr; j < n; j++) + cost[i + n * j] = 0; + + res = compute_assignment(n, n, cost, a2b, b2a); + + for (i = 0; i < a->nr; i++) + if (a2b[i] >= 0 && a2b[i] < b->nr) { + struct patch_util *a_util = a->items[i].util; + struct patch_util *b_util = b->items[a2b[i]].util; + + a_util->matching = a2b[i]; + b_util->matching = i; + } + + free(cost); + free(a2b); + free(b2a); + + return res; +} + +static const char *short_oid(struct patch_util *util) +{ + return find_unique_abbrev(&util->oid, DEFAULT_ABBREV); +} + +static void output(struct string_list *a, struct string_list *b) +{ + int i; + + for (i = 0; i < b->nr; i++) { + struct patch_util *util = b->items[i].util, *prev; + + if (util->matching < 0) + printf("-: -------- > %d: %s\n", + i + 1, short_oid(util)); + else { + prev = a->items[util->matching].util; + printf("%d: %s ! %d: %s\n", + util->matching + 1, short_oid(prev), + i + 1, short_oid(util)); + } + } + + for (i = 0; i < a->nr; i++) { + struct patch_util *util = a->items[i].util; + + if (util->matching < 0) + printf("%d: %s < -: --------\n", + i + 1, short_oid(util)); + } +} + int cmd_branch_diff(int argc, const char **argv, const char *prefix) { double creation_weight = 0.6; @@ -30,9 +309,63 @@ int cmd_branch_diff(int argc, const char **argv, const char *prefix) 0, parse_creation_weight }, OPT_END() }; + int res = 0; + struct strbuf range1 = STRBUF_INIT, range2 = STRBUF_INIT; + struct string_list branch1 = STRING_LIST_INIT_DUP; + struct string_list branch2 = STRING_LIST_INIT_DUP; argc = parse_options(argc, argv, NULL, options, builtin_branch_diff_usage, 0); - return 0; + 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 == 3) { + strbuf_addf(&range1, "%s..%s", argv[0], argv[1]); + strbuf_addf(&range2, "%s..%s", argv[0], argv[2]); + } else if (argc == 1) { + const char *b = strstr(argv[0], "..."), *a = argv[0]; + int a_len; + + if (!b) + die(_("single arg format requires a symmetric range")); + + a_len = (int)(b - a); + if (!a_len) { + a = "HEAD"; + a_len = strlen(a); + } + b += 3; + if (!*b) + b = "HEAD"; + strbuf_addf(&range1, "%s..%.*s", b, a_len, a); + strbuf_addf(&range2, "%.*s..%s", a_len, a, b); + } 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); + + if (!res) { + find_exact_matches(&branch1, &branch2); + res = get_correspondences(&branch1, &branch2, creation_weight); + if (!res) + output(&branch1, &branch2); + } + + strbuf_release(&range1); + strbuf_release(&range2); + string_list_clear(&branch1, 1); + string_list_clear(&branch2, 1); + + return !!res; } -- 2.17.0.409.g71698f11835
