summaryrefslogtreecommitdiff
path: root/diffcore-rename.c
diff options
context:
space:
mode:
Diffstat (limited to 'diffcore-rename.c')
-rw-r--r--diffcore-rename.c416
1 files changed, 416 insertions, 0 deletions
diff --git a/diffcore-rename.c b/diffcore-rename.c
new file mode 100644
index 0000000000..6a52699f73
--- /dev/null
+++ b/diffcore-rename.c
@@ -0,0 +1,416 @@
+/*
+ * Copyright (C) 2005 Junio C Hamano
+ */
+#include "cache.h"
+#include "diff.h"
+#include "diffcore.h"
+#include "delta.h"
+#include "count-delta.h"
+
+/* Table of rename/copy destinations */
+
+static struct diff_rename_dst {
+ struct diff_filespec *two;
+ struct diff_filepair *pair;
+} *rename_dst;
+static int rename_dst_nr, rename_dst_alloc;
+
+static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
+ int insert_ok)
+{
+ int first, last;
+
+ first = 0;
+ last = rename_dst_nr;
+ while (last > first) {
+ int next = (last + first) >> 1;
+ struct diff_rename_dst *dst = &(rename_dst[next]);
+ int cmp = strcmp(two->path, dst->two->path);
+ if (!cmp)
+ return dst;
+ if (cmp < 0) {
+ last = next;
+ continue;
+ }
+ first = next+1;
+ }
+ /* not found */
+ if (!insert_ok)
+ return NULL;
+ /* insert to make it at "first" */
+ if (rename_dst_alloc <= rename_dst_nr) {
+ rename_dst_alloc = alloc_nr(rename_dst_alloc);
+ rename_dst = xrealloc(rename_dst,
+ rename_dst_alloc * sizeof(*rename_dst));
+ }
+ rename_dst_nr++;
+ if (first < rename_dst_nr)
+ memmove(rename_dst + first + 1, rename_dst + first,
+ (rename_dst_nr - first - 1) * sizeof(*rename_dst));
+ rename_dst[first].two = two;
+ rename_dst[first].pair = NULL;
+ return &(rename_dst[first]);
+}
+
+/* Table of rename/copy src files */
+static struct diff_rename_src {
+ struct diff_filespec *one;
+ unsigned src_stays : 1;
+} *rename_src;
+static int rename_src_nr, rename_src_alloc;
+
+static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
+ int src_stays)
+{
+ int first, last;
+
+ first = 0;
+ last = rename_src_nr;
+ while (last > first) {
+ int next = (last + first) >> 1;
+ struct diff_rename_src *src = &(rename_src[next]);
+ int cmp = strcmp(one->path, src->one->path);
+ if (!cmp)
+ return src;
+ if (cmp < 0) {
+ last = next;
+ continue;
+ }
+ first = next+1;
+ }
+
+ /* insert to make it at "first" */
+ if (rename_src_alloc <= rename_src_nr) {
+ rename_src_alloc = alloc_nr(rename_src_alloc);
+ rename_src = xrealloc(rename_src,
+ rename_src_alloc * sizeof(*rename_src));
+ }
+ rename_src_nr++;
+ if (first < rename_src_nr)
+ memmove(rename_src + first + 1, rename_src + first,
+ (rename_src_nr - first - 1) * sizeof(*rename_src));
+ rename_src[first].one = one;
+ rename_src[first].src_stays = src_stays;
+ return &(rename_src[first]);
+}
+
+static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst)
+{
+ if (src->sha1_valid && dst->sha1_valid &&
+ !memcmp(src->sha1, dst->sha1, 20))
+ return 1;
+ if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
+ return 0;
+ if (src->size != dst->size)
+ return 0;
+ if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
+ return 0;
+ if (src->size == dst->size &&
+ !memcmp(src->data, dst->data, src->size))
+ return 1;
+ return 0;
+}
+
+struct diff_score {
+ int src; /* index in rename_src */
+ int dst; /* index in rename_dst */
+ int score;
+};
+
+static int estimate_similarity(struct diff_filespec *src,
+ struct diff_filespec *dst,
+ int minimum_score)
+{
+ /* src points at a file that existed in the original tree (or
+ * optionally a file in the destination tree) and dst points
+ * at a newly created file. They may be quite similar, in which
+ * case we want to say src is renamed to dst or src is copied into
+ * dst, and then some edit has been applied to dst.
+ *
+ * Compare them and return how similar they are, representing
+ * the score as an integer between 0 and MAX_SCORE.
+ *
+ * When there is an exact match, it is considered a better
+ * match than anything else; the destination does not even
+ * call into this function in that case.
+ */
+ void *delta;
+ unsigned long delta_size, base_size, src_copied, literal_added;
+ unsigned long delta_limit;
+ int score;
+
+ /* We deal only with regular files. Symlink renames are handled
+ * only when they are exact matches --- in other words, no edits
+ * after renaming.
+ */
+ if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
+ return 0;
+
+ delta_size = ((src->size < dst->size) ?
+ (dst->size - src->size) : (src->size - dst->size));
+ base_size = ((src->size < dst->size) ? src->size : dst->size);
+
+ /* We would not consider edits that change the file size so
+ * drastically. delta_size must be smaller than
+ * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
+ *
+ * Note that base_size == 0 case is handled here already
+ * and the final score computation below would not have a
+ * divide-by-zero issue.
+ */
+ if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
+ return 0;
+
+ if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
+ return 0; /* error but caught downstream */
+
+ delta_limit = base_size * (MAX_SCORE-minimum_score) / MAX_SCORE;
+ delta = diff_delta(src->data, src->size,
+ dst->data, dst->size,
+ &delta_size, delta_limit);
+ if (!delta)
+ /* If delta_limit is exceeded, we have too much differences */
+ return 0;
+
+ /* A delta that has a lot of literal additions would have
+ * big delta_size no matter what else it does.
+ */
+ if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
+ return 0;
+
+ /* Estimate the edit size by interpreting delta. */
+ if (count_delta(delta, delta_size, &src_copied, &literal_added)) {
+ free(delta);
+ return 0;
+ }
+ free(delta);
+
+ /* Extent of damage */
+ if (src->size + literal_added < src_copied)
+ delta_size = 0;
+ else
+ delta_size = (src->size - src_copied) + literal_added;
+
+ /*
+ * Now we will give some score to it. 100% edit gets 0 points
+ * and 0% edit gets MAX_SCORE points.
+ */
+ score = MAX_SCORE - (MAX_SCORE * delta_size / base_size);
+ if (score < 0) return 0;
+ if (MAX_SCORE < score) return MAX_SCORE;
+ return score;
+}
+
+static void record_rename_pair(struct diff_queue_struct *renq,
+ int dst_index, int src_index, int score)
+{
+ struct diff_filespec *one, *two, *src, *dst;
+ struct diff_filepair *dp;
+
+ if (rename_dst[dst_index].pair)
+ die("internal error: dst already matched.");
+
+ src = rename_src[src_index].one;
+ one = alloc_filespec(src->path);
+ fill_filespec(one, src->sha1, src->mode);
+
+ dst = rename_dst[dst_index].two;
+ two = alloc_filespec(dst->path);
+ fill_filespec(two, dst->sha1, dst->mode);
+
+ dp = diff_queue(renq, one, two);
+ dp->score = score;
+ dp->source_stays = rename_src[src_index].src_stays;
+ rename_dst[dst_index].pair = dp;
+}
+
+/*
+ * We sort the rename similarity matrix with the score, in descending
+ * order (the most similar first).
+ */
+static int score_compare(const void *a_, const void *b_)
+{
+ const struct diff_score *a = a_, *b = b_;
+ return b->score - a->score;
+}
+
+void diffcore_rename(int detect_rename, int minimum_score)
+{
+ struct diff_queue_struct *q = &diff_queued_diff;
+ struct diff_queue_struct renq, outq;
+ struct diff_score *mx;
+ int i, j;
+ int num_create, num_src, dst_cnt;
+
+ if (!minimum_score)
+ minimum_score = DEFAULT_RENAME_SCORE;
+ renq.queue = NULL;
+ renq.nr = renq.alloc = 0;
+
+ for (i = 0; i < q->nr; i++) {
+ struct diff_filepair *p = q->queue[i];
+ if (!DIFF_FILE_VALID(p->one))
+ if (!DIFF_FILE_VALID(p->two))
+ continue; /* unmerged */
+ else
+ locate_rename_dst(p->two, 1);
+ else if (!DIFF_FILE_VALID(p->two)) {
+ /* If the source is a broken "delete", and
+ * they did not really want to get broken,
+ * that means the source actually stays.
+ */
+ int stays = (p->broken_pair && !p->score);
+ register_rename_src(p->one, stays);
+ }
+ else if (detect_rename == DIFF_DETECT_COPY)
+ register_rename_src(p->one, 1);
+ }
+ if (rename_dst_nr == 0)
+ goto cleanup; /* nothing to do */
+
+ /* We really want to cull the candidates list early
+ * with cheap tests in order to avoid doing deltas.
+ */
+ for (i = 0; i < rename_dst_nr; i++) {
+ struct diff_filespec *two = rename_dst[i].two;
+ for (j = 0; j < rename_src_nr; j++) {
+ struct diff_filespec *one = rename_src[j].one;
+ if (!is_exact_match(one, two))
+ continue;
+ record_rename_pair(&renq, i, j, MAX_SCORE);
+ break; /* we are done with this entry */
+ }
+ }
+ diff_debug_queue("done detecting exact", &renq);
+
+ /* Have we run out the created file pool? If so we can avoid
+ * doing the delta matrix altogether.
+ */
+ if (renq.nr == rename_dst_nr)
+ goto cleanup;
+
+ num_create = (rename_dst_nr - renq.nr);
+ num_src = rename_src_nr;
+ mx = xmalloc(sizeof(*mx) * num_create * num_src);
+ for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
+ int base = dst_cnt * num_src;
+ struct diff_filespec *two = rename_dst[i].two;
+ if (rename_dst[i].pair)
+ continue; /* dealt with exact match already. */
+ for (j = 0; j < rename_src_nr; j++) {
+ struct diff_filespec *one = rename_src[j].one;
+ struct diff_score *m = &mx[base+j];
+ m->src = j;
+ m->dst = i;
+ m->score = estimate_similarity(one, two,
+ minimum_score);
+ }
+ dst_cnt++;
+ }
+ /* cost matrix sorted by most to least similar pair */
+ qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
+ for (i = 0; i < num_create * num_src; i++) {
+ struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
+ if (dst->pair)
+ continue; /* already done, either exact or fuzzy. */
+ if (mx[i].score < minimum_score)
+ break; /* there is no more usable pair. */
+ record_rename_pair(&renq, mx[i].dst, mx[i].src, mx[i].score);
+ }
+ free(mx);
+ diff_debug_queue("done detecting fuzzy", &renq);
+
+ cleanup:
+ /* At this point, we have found some renames and copies and they
+ * are kept in renq. The original list is still in *q.
+ */
+ outq.queue = NULL;
+ outq.nr = outq.alloc = 0;
+ for (i = 0; i < q->nr; i++) {
+ struct diff_filepair *p = q->queue[i];
+ struct diff_filepair *pair_to_free = NULL;
+
+ if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
+ /*
+ * Creation
+ *
+ * We would output this create record if it has
+ * not been turned into a rename/copy already.
+ */
+ struct diff_rename_dst *dst =
+ locate_rename_dst(p->two, 0);
+ if (dst && dst->pair) {
+ diff_q(&outq, dst->pair);
+ pair_to_free = p;
+ }
+ else
+ /* no matching rename/copy source, so
+ * record this as a creation.
+ */
+ diff_q(&outq, p);
+ }
+ else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
+ /*
+ * Deletion
+ *
+ * We would output this delete record if:
+ *
+ * (1) this is a broken delete and the counterpart
+ * broken create remains in the output; or
+ * (2) this is not a broken delete, and renq does
+ * not have a rename/copy to move p->one->path
+ * out.
+ *
+ * Otherwise, the counterpart broken create
+ * has been turned into a rename-edit; or
+ * delete did not have a matching create to
+ * begin with.
+ */
+ if (DIFF_PAIR_BROKEN(p)) {
+ /* broken delete */
+ struct diff_rename_dst *dst =
+ locate_rename_dst(p->one, 0);
+ if (dst && dst->pair)
+ /* counterpart is now rename/copy */
+ pair_to_free = p;
+ }
+ else {
+ for (j = 0; j < renq.nr; j++)
+ if (!strcmp(renq.queue[j]->one->path,
+ p->one->path))
+ break;
+ if (j < renq.nr)
+ /* this path remains */
+ pair_to_free = p;
+ }
+
+ if (pair_to_free)
+ ;
+ else
+ diff_q(&outq, p);
+ }
+ else if (!diff_unmodified_pair(p))
+ /* all the usual ones need to be kept */
+ diff_q(&outq, p);
+ else
+ /* no need to keep unmodified pairs */
+ pair_to_free = p;
+
+ if (pair_to_free)
+ diff_free_filepair(pair_to_free);
+ }
+ diff_debug_queue("done copying original", &outq);
+
+ free(renq.queue);
+ free(q->queue);
+ *q = outq;
+ diff_debug_queue("done collapsing", q);
+
+ free(rename_dst);
+ rename_dst = NULL;
+ rename_dst_nr = rename_dst_alloc = 0;
+ free(rename_src);
+ rename_src = NULL;
+ rename_src_nr = rename_src_alloc = 0;
+ return;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-13 15:34:37 +0000