X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=combine-diff.c;h=243f96775aaa058581491544f53f05a3bd038cc0;hb=d41df15e6913e8f7e1b5d656bb51dc4268232c36;hp=b0846bc09bd2dc2c63f7ec702ac021e192606d93;hpb=e228340961e0f48c6b818251bd4729b2d19647e4;p=git.git

diff --git a/combine-diff.c b/combine-diff.c
index b0846bc0..243f9677 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -4,14 +4,6 @@
 #include "diffcore.h"
 #include "quote.h"
 
-struct path_list {
-	struct path_list *next;
-	int len;
-	char *path;
-	unsigned char sha1[20];
-	unsigned char parent_sha1[FLEX_ARRAY][20];
-};
-
 static int uninteresting(struct diff_filepair *p)
 {
 	if (diff_unmodified_pair(p))
@@ -21,15 +13,14 @@ static int uninteresting(struct diff_filepair *p)
 	return 0;
 }
 
-static struct path_list *intersect_paths(struct path_list *curr,
-					 int n, int num_parent)
+static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr, int n, int num_parent)
 {
 	struct diff_queue_struct *q = &diff_queued_diff;
-	struct path_list *p;
+	struct combine_diff_path *p;
 	int i;
 
 	if (!n) {
-		struct path_list *list = NULL, **tail = &list;
+		struct combine_diff_path *list = NULL, **tail = &list;
 		for (i = 0; i < q->nr; i++) {
 			int len;
 			const char *path;
@@ -271,87 +262,219 @@ static int interesting(struct sline *sline, unsigned long all_mask)
 	return ((sline->flag & all_mask) != all_mask || sline->lost_head);
 }
 
-static unsigned long line_diff_parents(struct sline *sline, unsigned long all_mask)
+static unsigned long line_common_diff(struct sline *sline, unsigned long all_mask)
 {
 	/*
-	 * Look at the line and see from which parents we have difference.
-	 * Lower bits of sline->flag records if the parent had this line,
-	 * so XOR with all_mask gives us on-bits for parents we have
-	 * differences with.
+	 * Look at the line and see from which parents we have the
+	 * same difference.
+	 */
+
+	/* Lower bits of sline->flag records if the parent had this
+	 * line, so XOR with all_mask gives us on-bits for parents we
+	 * have differences with.
 	 */
-	unsigned long parents = (sline->flag ^ all_mask);
+	unsigned long common_adds = (sline->flag ^ all_mask) & all_mask;
+	unsigned long common_removes = all_mask;
+
+	/* If all the parents have this line, that also counts as
+	 * having the same difference.
+	 */
+	if (!common_adds)
+		common_adds = all_mask;
+
 	if (sline->lost_head) {
+		/* Lost head list records the lines removed from
+		 * the parents, and parent_map records from which
+		 * parent the line was removed.
+		 */
 		struct lline *ll;
-		for (ll = sline->lost_head; ll; ll = ll->next)
-			parents |= ll->parent_map;
+		for (ll = sline->lost_head; ll; ll = ll->next) {
+			common_removes &= ll->parent_map;
+		}
 	}
-	return parents & all_mask;
+	return common_adds & common_removes;
 }
 
-static void make_hunks(struct sline *sline, unsigned long cnt,
-		       int num_parent, int dense)
+static unsigned long line_all_diff(struct sline *sline, unsigned long all_mask)
+{
+	/*
+	 * Look at the line and see from which parents we have some difference.
+	 */
+	unsigned long different = (sline->flag ^ all_mask) & all_mask;
+	if (sline->lost_head) {
+		/* Lost head list records the lines removed from
+		 * the parents, and parent_map records from which
+		 * parent the line was removed.
+		 */
+		struct lline *ll;
+		for (ll = sline->lost_head; ll; ll = ll->next) {
+			different |= ll->parent_map;
+		}
+	}
+	return different;
+}
+
+static unsigned long adjust_hunk_tail(struct sline *sline,
+				      unsigned long all_mask,
+				      unsigned long hunk_begin,
+				      unsigned long i)
+{
+	/* i points at the first uninteresting line.
+	 * If the last line of the hunk was interesting
+	 * only because it has some deletion, then
+	 * it is not all that interesting for the
+	 * purpose of giving trailing context lines.
+	 */
+	if ((hunk_begin + 1 <= i) &&
+	    ((sline[i-1].flag & all_mask) == all_mask))
+		i--;
+	return i;
+}
+
+static unsigned long next_interesting(struct sline *sline,
+				      unsigned long mark,
+				      unsigned long i,
+				      unsigned long cnt,
+				      int uninteresting)
+{
+	while (i < cnt)
+		if (uninteresting ?
+		    !(sline[i].flag & mark) :
+		    (sline[i].flag & mark))
+			return i;
+		else
+			i++;
+	return cnt;
+}
+
+static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
 {
 	unsigned long all_mask = (1UL<<num_parent) - 1;
 	unsigned long mark = (1UL<<num_parent);
 	unsigned long i;
 
-	i = 0;
+	i = next_interesting(sline, mark, 0, cnt, 0);
+	if (cnt <= i)
+		return 0;
+
 	while (i < cnt) {
-		if (interesting(&sline[i], all_mask)) {
-			unsigned long j = (context < i) ? i - context : 0;
-			while (j <= i)
+		unsigned long j = (context < i) ? (i - context) : 0;
+		unsigned long k;
+		while (j < i)
+			sline[j++].flag |= mark;
+
+	again:
+		j = next_interesting(sline, mark, i, cnt, 1);
+		if (cnt <= j)
+			break; /* the rest are all interesting */
+
+		/* lookahead context lines */
+		k = next_interesting(sline, mark, j, cnt, 0);
+		j = adjust_hunk_tail(sline, all_mask, i, j);
+
+		if (k < j + context) {
+			/* k is interesting and [j,k) are not, but
+			 * paint them interesting because the gap is small.
+			 */
+			while (j < k)
 				sline[j++].flag |= mark;
-			while (++i < cnt) {
-				if (!interesting(&sline[i], all_mask))
-					break;
-				sline[i].flag |= mark;
-			}
-			j = (i + context < cnt) ? i + context : cnt;
-			while (i < j)
-				sline[i++].flag |= mark;
-			continue;
+			i = k;
+			goto again;
 		}
-		i++;
+
+		/* j is the first uninteresting line and there is
+		 * no overlap beyond it within context lines.
+		 */
+		i = k;
+		k = (j + context < cnt) ? j + context : cnt;
+		while (j < k)
+			sline[j++].flag |= mark;
+	}
+	return 1;
+}
+
+static int make_hunks(struct sline *sline, unsigned long cnt,
+		       int num_parent, int dense)
+{
+	unsigned long all_mask = (1UL<<num_parent) - 1;
+	unsigned long mark = (1UL<<num_parent);
+	unsigned long i;
+	int has_interesting = 0;
+
+	for (i = 0; i < cnt; i++) {
+		if (interesting(&sline[i], all_mask))
+			sline[i].flag |= mark;
+		else
+			sline[i].flag &= ~mark;
 	}
 	if (!dense)
-		return;
+		return give_context(sline, cnt, num_parent);
 
-	/* Look at each hunk, and if it contains changes from only
-	 * one parent, mark that uninteresting.
+	/* Look at each hunk, and if we have changes from only one
+	 * parent, or the changes are the same from all but one
+	 * parent, mark that uninteresting.
 	 */
 	i = 0;
 	while (i < cnt) {
-		int j, hunk_end, diffs;
-		unsigned long parents;
+		unsigned long j, hunk_begin, hunk_end;
+		int same, diff;
+		unsigned long same_diff, all_diff;
 		while (i < cnt && !(sline[i].flag & mark))
 			i++;
 		if (cnt <= i)
 			break; /* No more interesting hunks */
-		for (hunk_end = i + 1; hunk_end < cnt; hunk_end++)
-			if (!(sline[hunk_end].flag & mark))
-				break;
-		/* [i..hunk_end) are interesting.  Now is it from
-		 * only one parent?
-		 * If lost lines are only from one parent and
-		 * remaining lines existed in parents other than
-		 * that parent, then the hunk is not that interesting.
+		hunk_begin = i;
+		for (j = i + 1; j < cnt; j++) {
+			if (!(sline[j].flag & mark)) {
+				/* Look beyond the end to see if there
+				 * is an interesting line after this
+				 * hunk within context span.
+				 */
+				unsigned long la; /* lookahead */
+				int contin = 0;
+				la = adjust_hunk_tail(sline, all_mask,
+						     hunk_begin, j);
+				la = (la + context < cnt) ?
+					(la + context) : cnt;
+				while (j <= --la) {
+					if (sline[la].flag & mark) {
+						contin = 1;
+						break;
+					}
+				}
+				if (!contin)
+					break;
+				j = la;
+			}
+		}
+		hunk_end = j;
+
+		/* [i..hunk_end) are interesting.  Now does it have
+		 * the same change with all but one parent?
 		 */
-		parents = 0;
-		diffs = 0;
-		for (j = i; j < hunk_end; j++)
-			parents |= line_diff_parents(sline + j, all_mask);
-		/* Now, how many bits from [0..num_parent) are on? */
+		same_diff = all_mask;
+		all_diff = 0;
+		for (j = i; j < hunk_end; j++) {
+			same_diff &= line_common_diff(sline + j, all_mask);
+			all_diff |= line_all_diff(sline + j, all_mask);
+		}
+		diff = same = 0;
 		for (j = 0; j < num_parent; j++) {
-			if (parents & (1UL<<j))
-				diffs++;
+			if (same_diff & (1UL<<j))
+				same++;
+			if (all_diff & (1UL<<j))
+				diff++;
 		}
-		if (diffs < 2) {
+		if ((num_parent - 1 <= same) || (diff == 1)) {
 			/* This hunk is not that interesting after all */
-			for (j = i; j < hunk_end; j++)
+			for (j = hunk_begin; j < hunk_end; j++)
 				sline[j].flag &= ~mark;
 		}
 		i = hunk_end;
 	}
+
+	has_interesting = give_context(sline, cnt, num_parent);
+	return has_interesting;
 }
 
 static void dump_sline(struct sline *sline, int cnt, int num_parent)
@@ -400,18 +523,52 @@ static void dump_sline(struct sline *sline, int cnt, int num_parent)
 	}
 }
 
-static void show_combined_diff(struct path_list *elem, int num_parent,
-			       int dense)
+int show_combined_diff(struct combine_diff_path *elem, int num_parent,
+		       int dense, const char *header, int show_empty)
 {
 	unsigned long size, cnt, lno;
 	char *result, *cp, *ep;
 	struct sline *sline; /* survived lines */
-	int i;
-	char ourtmp[TMPPATHLEN];
+	int i, show_hunks, shown_header = 0;
+	char ourtmp_buf[TMPPATHLEN];
+	char *ourtmp = ourtmp_buf;
 
 	/* Read the result of merge first */
-	result = grab_blob(elem->sha1, &size);
-	write_to_temp_file(ourtmp, result, size);
+	if (memcmp(elem->sha1, null_sha1, 20)) {
+		result = grab_blob(elem->sha1, &size);
+		write_to_temp_file(ourtmp, result, size);
+	}
+	else {
+		struct stat st;
+		int fd;
+		ourtmp = elem->path;
+		if (0 <= (fd = open(ourtmp, O_RDONLY)) &&
+		    !fstat(fd, &st)) {
+			int len = st.st_size;
+			int cnt = 0;
+
+			size = len;
+			result = xmalloc(len + 1);
+			while (cnt < len) {
+				int done = xread(fd, result+cnt, len-cnt);
+				if (done == 0)
+					break;
+				if (done < 0)
+					die("read error '%s'", ourtmp);
+				cnt += done;
+			}
+			result[len] = 0;
+		}
+		else {
+			/* deleted file */
+			size = 0;
+			result = xmalloc(1);
+			result[0] = 0;
+			ourtmp = "/dev/null";
+		}
+		if (0 <= fd)
+			close(fd);
+	}
 
 	for (cnt = 0, cp = result; cp - result < size; cp++) {
 		if (*cp == '\n')
@@ -442,10 +599,23 @@ static void show_combined_diff(struct path_list *elem, int num_parent,
 	for (i = 0; i < num_parent; i++)
 		combine_diff(elem->parent_sha1[i], ourtmp, sline, cnt, i);
 
-	make_hunks(sline, cnt, num_parent, dense);
+	show_hunks = make_hunks(sline, cnt, num_parent, dense);
 
-	dump_sline(sline, cnt, num_parent);
-	unlink(ourtmp);
+	if (header && (show_hunks || show_empty)) {
+		shown_header++;
+		puts(header);
+	}
+	if (show_hunks) {
+		printf("diff --%s ", dense ? "cc" : "combined");
+		if (quote_c_style(elem->path, NULL, NULL, 0))
+			quote_c_style(elem->path, NULL, stdout, 0);
+		else
+			printf("%s", elem->path);
+		putchar('\n');
+		dump_sline(sline, cnt, num_parent);
+	}
+	if (ourtmp == ourtmp_buf)
+		unlink(ourtmp);
 	free(result);
 
 	for (i = 0; i < cnt; i++) {
@@ -459,6 +629,7 @@ static void show_combined_diff(struct path_list *elem, int num_parent,
 		}
 	}
 	free(sline);
+	return shown_header;
 }
 
 int diff_tree_combined_merge(const unsigned char *sha1,
@@ -468,7 +639,7 @@ int diff_tree_combined_merge(const unsigned char *sha1,
 	struct commit *commit = lookup_commit(sha1);
 	struct diff_options diffopts;
 	struct commit_list *parents;
-	struct path_list *p, *paths = NULL;
+	struct combine_diff_path *p, *paths = NULL;
 	int num_parent, i, num_paths;
 
 	diff_setup(&diffopts);
@@ -498,23 +669,18 @@ int diff_tree_combined_merge(const unsigned char *sha1,
 			num_paths++;
 	}
 	if (num_paths || show_empty_merge) {
-		puts(header);
 		for (p = paths; p; p = p->next) {
 			if (!p->len)
 				continue;
-			printf("diff --%s ", dense ? "cc" : "combined");
-			if (quote_c_style(p->path, NULL, NULL, 0))
-				quote_c_style(p->path, NULL, stdout, 0);
-			else
-				printf("%s", p->path);
-			putchar('\n');
-			show_combined_diff(p, num_parent, dense);
+			if (show_combined_diff(p, num_parent, dense, header,
+					       show_empty_merge))
+				header = NULL;
 		}
 	}
 
 	/* Clean things up */
 	while (paths) {
-		struct path_list *tmp = paths;
+		struct combine_diff_path *tmp = paths;
 		paths = paths->next;
 		free(tmp);
 	}