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-rw-r--r--diffcore-rename.c443
1 files changed, 443 insertions, 0 deletions
diff --git a/diffcore-rename.c b/diffcore-rename.c
new file mode 100644
index 0000000..8aa8f84
--- /dev/null
+++ b/diffcore-rename.c
@@ -0,0 +1,443 @@
+/*
+ * Copyright (C) 2005 Junio C Hamano
+ */
+#include "cache.h"
+#include "diff.h"
+#include "diffcore.h"
+#include "delta.h"
+
+struct diff_rename_pool {
+ struct diff_filespec **s;
+ int nr, alloc;
+};
+
+static void diff_rename_pool_clear(struct diff_rename_pool *pool)
+{
+ pool->s = NULL; pool->nr = pool->alloc = 0;
+}
+
+static void diff_rename_pool_add(struct diff_rename_pool *pool,
+ struct diff_filespec *s)
+{
+ if (S_ISDIR(s->mode))
+ return; /* rename/copy patch for tree does not make sense. */
+
+ if (pool->alloc <= pool->nr) {
+ pool->alloc = alloc_nr(pool->alloc);
+ pool->s = xrealloc(pool->s,
+ sizeof(*(pool->s)) * pool->alloc);
+ }
+ pool->s[pool->nr] = s;
+ pool->nr++;
+}
+
+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) || diff_populate_filespec(dst))
+ /* this is an error but will be caught downstream */
+ return 0;
+ if (src->size == dst->size &&
+ !memcmp(src->data, dst->data, src->size))
+ return 1;
+ return 0;
+}
+
+struct diff_score {
+ struct diff_filespec *src;
+ struct diff_filespec *dst;
+ int score;
+ int rank;
+};
+
+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 10000, except
+ * where they match exactly it is considered better than anything
+ * else.
+ */
+ void *delta;
+ unsigned long delta_size;
+ int score;
+
+ delta_size = ((src->size < dst->size) ?
+ (dst->size - src->size) : (src->size - dst->size));
+
+ /* We would not consider rename followed by more than
+ * minimum_score/MAX_SCORE edits; that is, delta_size must be smaller
+ * than (src->size + dst->size)/2 * minimum_score/MAX_SCORE,
+ * which means...
+ */
+
+ if ((src->size+dst->size)*minimum_score < delta_size*MAX_SCORE*2)
+ return 0;
+
+ delta = diff_delta(src->data, src->size,
+ dst->data, dst->size,
+ &delta_size);
+ free(delta);
+
+ /* This "delta" is really xdiff with adler32 and all the
+ * overheads but it is a quick and dirty approximation.
+ *
+ * Now we will give some score to it. 100% edit gets
+ * 0 points and 0% edit gets MAX_SCORE points. That is, every
+ * 1/MAX_SCORE edit gets 1 point penalty. The amount of penalty is:
+ *
+ * (delta_size * 2 / (src->size + dst->size)) * MAX_SCORE
+ *
+ */
+ score = MAX_SCORE-(MAX_SCORE*2*delta_size/(src->size+dst->size));
+ if (score < 0) return 0;
+ if (MAX_SCORE < score) return MAX_SCORE;
+ return score;
+}
+
+static void record_rename_pair(struct diff_queue_struct *outq,
+ struct diff_filespec *src,
+ struct diff_filespec *dst,
+ int rank,
+ int score)
+{
+ /* The rank is used to sort the final output, because there
+ * are certain dependencies.
+ *
+ * - rank #0 depends on deleted ones.
+ * - rank #1 depends on kept files before they are modified.
+ * - rank #2 depends on kept files after they are modified;
+ * currently not used.
+ *
+ * Therefore, the final output order should be:
+ *
+ * 1. rank #0 rename/copy diffs.
+ * 2. deletions in the original.
+ * 3. rank #1 rename/copy diffs.
+ * 4. additions and modifications in the original.
+ * 5. rank #2 rename/copy diffs; currently not used.
+ *
+ * To achieve this sort order, we give xform_work the number
+ * above.
+ */
+ struct diff_file_pair *dp = diff_queue(outq, src, dst);
+ dp->xfrm_work = (rank * 2 + 1) | (score<<RENAME_SCORE_SHIFT);
+ dst->xfrm_flags |= RENAME_DST_MATCHED;
+}
+
+#if 0
+static void debug_filespec(struct diff_filespec *s, int x, const char *one)
+{
+ fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
+ x, one,
+ s->path,
+ s->file_valid ? "valid" : "invalid",
+ s->mode,
+ s->sha1_valid ? sha1_to_hex(s->sha1) : "");
+ fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
+ x, one,
+ s->size, s->xfrm_flags);
+}
+
+static void debug_filepair(const struct diff_file_pair *p, int i)
+{
+ debug_filespec(p->one, i, "one");
+ debug_filespec(p->two, i, "two");
+ fprintf(stderr, "pair flags %d, orig order %d, score %d\n",
+ (p->xfrm_work & ((1<<RENAME_SCORE_SHIFT) - 1)),
+ p->orig_order,
+ (p->xfrm_work >> RENAME_SCORE_SHIFT));
+}
+
+static void debug_queue(const char *msg, struct diff_queue_struct *q)
+{
+ int i;
+ if (msg)
+ fprintf(stderr, "%s\n", msg);
+ fprintf(stderr, "q->nr = %d\n", q->nr);
+ for (i = 0; i < q->nr; i++) {
+ struct diff_file_pair *p = q->queue[i];
+ debug_filepair(p, i);
+ }
+}
+#else
+#define debug_queue(a,b) do { ; /*nothing*/ } while(0)
+#endif
+
+/*
+ * We sort the outstanding diff entries according to the rank (see
+ * comment at the beginning of record_rename_pair) and tiebreak with
+ * the order in the original input.
+ */
+static int rank_compare(const void *a_, const void *b_)
+{
+ const struct diff_file_pair *a = *(const struct diff_file_pair **)a_;
+ const struct diff_file_pair *b = *(const struct diff_file_pair **)b_;
+ int a_rank = a->xfrm_work & ((1<<RENAME_SCORE_SHIFT) - 1);
+ int b_rank = b->xfrm_work & ((1<<RENAME_SCORE_SHIFT) - 1);
+
+ if (a_rank != b_rank)
+ return a_rank - b_rank;
+ return a->orig_order - b->orig_order;
+}
+
+/*
+ * We sort the rename similarity matrix with the score, in descending
+ * order (more 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;
+}
+
+static int needs_to_stay(struct diff_queue_struct *q, int i,
+ struct diff_filespec *it)
+{
+ /* If it will be used in later entry (either stay or used
+ * as the source of rename/copy), we need to copy, not rename.
+ */
+ while (i < q->nr) {
+ struct diff_file_pair *p = q->queue[i++];
+ if (!p->two->file_valid)
+ continue; /* removed is fine */
+ if (strcmp(p->one->path, it->path))
+ continue; /* not relevant */
+
+ /* p has its src set to *it and it is not a delete;
+ * it will be used for in-place change or rename/copy,
+ * so we cannot rename it out.
+ */
+ return 1;
+ }
+ return 0;
+}
+
+void diff_detect_rename(struct diff_queue_struct *q,
+ int detect_rename,
+ int minimum_score)
+{
+ struct diff_queue_struct outq;
+ struct diff_rename_pool created, deleted, stay;
+ struct diff_rename_pool *(srcs[2]);
+ struct diff_score *mx;
+ int h, i, j;
+ int num_create, num_src, dst_cnt, src_cnt;
+
+ outq.queue = NULL;
+ outq.nr = outq.alloc = 0;
+
+ diff_rename_pool_clear(&created);
+ diff_rename_pool_clear(&deleted);
+ diff_rename_pool_clear(&stay);
+
+ srcs[0] = &deleted;
+ srcs[1] = &stay;
+
+ /* NEEDSWORK:
+ * (1) make sure we properly ignore but pass trees.
+ *
+ * (2) make sure we do right thing on the same path deleted
+ * and created in the same patch.
+ */
+
+ for (i = 0; i < q->nr; i++) {
+ struct diff_file_pair *p = q->queue[i];
+ if (!p->one->file_valid)
+ if (!p->two->file_valid)
+ continue; /* ignore nonsense */
+ else
+ diff_rename_pool_add(&created, p->two);
+ else if (!p->two->file_valid)
+ diff_rename_pool_add(&deleted, p->one);
+ else if (1 < detect_rename) /* find copy, too */
+ diff_rename_pool_add(&stay, p->one);
+ }
+ if (created.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.
+ *
+ * With the current callers, we should not have already
+ * matched entries at this point, but it is nonetheless
+ * checked for sanity.
+ */
+ for (i = 0; i < created.nr; i++) {
+ if (created.s[i]->xfrm_flags & RENAME_DST_MATCHED)
+ continue; /* we have matched exactly already */
+ for (h = 0; h < sizeof(srcs)/sizeof(srcs[0]); h++) {
+ struct diff_rename_pool *p = srcs[h];
+ for (j = 0; j < p->nr; j++) {
+ if (!is_exact_match(p->s[j], created.s[i]))
+ continue;
+ record_rename_pair(&outq,
+ p->s[j], created.s[i], h,
+ MAX_SCORE);
+ break; /* we are done with this entry */
+ }
+ }
+ }
+ debug_queue("done detecting exact", &outq);
+
+ /* Have we run out the created file pool? If so we can avoid
+ * doing the delta matrix altogether.
+ */
+ if (outq.nr == created.nr)
+ goto flush_rest;
+
+ num_create = (created.nr - outq.nr);
+ num_src = deleted.nr + stay.nr;
+ mx = xmalloc(sizeof(*mx) * num_create * num_src);
+ for (dst_cnt = i = 0; i < created.nr; i++) {
+ int base = dst_cnt * num_src;
+ if (created.s[i]->xfrm_flags & RENAME_DST_MATCHED)
+ continue; /* dealt with exact match already. */
+ for (src_cnt = h = 0; h < sizeof(srcs)/sizeof(srcs[0]); h++) {
+ struct diff_rename_pool *p = srcs[h];
+ for (j = 0; j < p->nr; j++, src_cnt++) {
+ struct diff_score *m = &mx[base + src_cnt];
+ m->src = p->s[j];
+ m->dst = created.s[i];
+ m->score = estimate_similarity(m->src, m->dst,
+ minimum_score);
+ m->rank = h;
+ }
+ }
+ 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++) {
+ if (mx[i].dst->xfrm_flags & RENAME_DST_MATCHED)
+ continue; /* alreayd done, either exact or fuzzy. */
+ if (mx[i].score < minimum_score)
+ continue;
+ record_rename_pair(&outq,
+ mx[i].src, mx[i].dst, mx[i].rank,
+ mx[i].score);
+ }
+ free(mx);
+ debug_queue("done detecting fuzzy", &outq);
+
+ flush_rest:
+ /* At this point, we have found some renames and copies and they
+ * are kept in outq. The original list is still in *q.
+ *
+ * Scan the original list and move them into the outq; we will sort
+ * outq and swap it into the queue supplied to pass that to
+ * downstream, so we assign the sort keys in this loop.
+ *
+ * See comments at the top of record_rename_pair for numbers used
+ * to assign xfrm_work.
+ *
+ * Note that we have not annotated the diff_file_pair with any comment
+ * so there is nothing other than p to free.
+ */
+ for (i = 0; i < q->nr; i++) {
+ struct diff_file_pair *dp, *p = q->queue[i];
+ if (!p->one->file_valid) {
+ if (p->two->file_valid) {
+ /* creation */
+ dp = diff_queue(&outq, p->one, p->two);
+ dp->xfrm_work = 4;
+ }
+ /* otherwise it is a nonsense; just ignore it */
+ }
+ else if (!p->two->file_valid) {
+ /* deletion */
+ dp = diff_queue(&outq, p->one, p->two);
+ dp->xfrm_work = 2;
+ }
+ else {
+ /* modification, or stay as is */
+ dp = diff_queue(&outq, p->one, p->two);
+ dp->xfrm_work = 4;
+ }
+ free(p);
+ }
+ debug_queue("done copying original", &outq);
+
+ /* Sort outq */
+ qsort(outq.queue, outq.nr, sizeof(outq.queue[0]), rank_compare);
+
+ debug_queue("done sorting", &outq);
+
+ free(q->queue);
+ q->nr = q->alloc = 0;
+ q->queue = NULL;
+
+ /* Copy it out to q, removing duplicates. */
+ for (i = 0; i < outq.nr; i++) {
+ struct diff_file_pair *p = outq.queue[i];
+ if (!p->one->file_valid) {
+ /* created */
+ if (p->two->xfrm_flags & RENAME_DST_MATCHED)
+ ; /* rename/copy created it already */
+ else
+ diff_queue(q, p->one, p->two);
+ }
+ else if (!p->two->file_valid) {
+ /* deleted */
+ if (p->one->xfrm_flags & RENAME_SRC_GONE)
+ ; /* rename/copy deleted it already */
+ else
+ diff_queue(q, p->one, p->two);
+ }
+ else if (strcmp(p->one->path, p->two->path)) {
+ /* rename or copy */
+ struct diff_file_pair *dp =
+ diff_queue(q, p->one, p->two);
+ int msglen = (strlen(p->one->path) +
+ strlen(p->two->path) + 100);
+ int score = (p->xfrm_work >> RENAME_SCORE_SHIFT);
+ dp->xfrm_msg = xmalloc(msglen);
+
+ /* if we have a later entry that is a rename/copy
+ * that depends on p->one, then we copy here.
+ * otherwise we rename it.
+ */
+ if (needs_to_stay(&outq, i+1, p->one)) {
+ /* copy it */
+ sprintf(dp->xfrm_msg,
+ "similarity index %d%%\n"
+ "copy from %s\n"
+ "copy to %s\n",
+ (int)(0.5 + score * 100 / MAX_SCORE),
+ p->one->path, p->two->path);
+ }
+ else {
+ /* rename it, and mark it as gone. */
+ p->one->xfrm_flags |= RENAME_SRC_GONE;
+ sprintf(dp->xfrm_msg,
+ "similarity index %d%%\n"
+ "rename old %s\n"
+ "rename new %s\n",
+ (int)(0.5 + score * 100 / MAX_SCORE),
+ p->one->path, p->two->path);
+ }
+ }
+ else
+ /* otherwise it is a modified (or stayed) entry */
+ diff_queue(q, p->one, p->two);
+ free(p);
+ }
+
+ free(outq.queue);
+ debug_queue("done collapsing", q);
+
+ cleanup:
+ free(created.s);
+ free(deleted.s);
+ free(stay.s);
+ return;
+}
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