git-blame --incremental

This adds --incremental option to help GUI porcelains to show
the result from git-blame incrementally.  The output gives the
origin information in the same format as the porcelain format.
The first line has commit object name, the line number of the
first line in the group in the original file, the line number of
that file in the final image, and number of lines in the group.
Then subsequent lines show the metainformation for the commit
when the commit is shown for the first time, except the filename
information is always shown (we cannot even make it conditional
to -C option as blame always follows the renaming of the file
wholesale).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-blame.c

@@ -13,6 +13,7 @@
 #include "diff.h"
 #include "diffcore.h"
 #include "revision.h"
+#include "quote.h"
 #include "xdiff-interface.h"
 
 static char blame_usage[] =
@@ -27,6 +28,7 @@ static char blame_usage[] =
 "  -p, --porcelain     Show in a format designed for machine consumption\n"
 "  -L n,m              Process only line range n,m, counting from 1\n"
 "  -M, -C              Find line movements within and across files\n"
+"  --incremental       Show blame entries as we find them, incrementally\n"
 "  -S revs-file        Use revisions from revs-file instead of calling git-rev-list\n";
 
 static int longest_file;
@@ -36,6 +38,7 @@ static int max_digits;
 static int max_score_digits;
 static int show_root;
 static int blank_boundary;
+static int incremental;
 
 #ifndef DEBUG
 #define DEBUG 0
@@ -1069,72 +1072,6 @@ static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
 		origin_decref(parent_origin[i]);
 }
 
-static void assign_blame(struct scoreboard *sb, struct rev_info *revs, int opt)
-{
-	while (1) {
-		struct blame_entry *ent;
-		struct commit *commit;
-		struct origin *suspect = NULL;
-
-		/* find one suspect to break down */
-		for (ent = sb->ent; !suspect && ent; ent = ent->next)
-			if (!ent->guilty)
-				suspect = ent->suspect;
-		if (!suspect)
-			return; /* all done */
-
-		origin_incref(suspect);
-		commit = suspect->commit;
-		if (!commit->object.parsed)
-			parse_commit(commit);
-		if (!(commit->object.flags & UNINTERESTING) &&
-		    !(revs->max_age != -1 && commit->date  < revs->max_age))
-			pass_blame(sb, suspect, opt);
-		else {
-			commit->object.flags |= UNINTERESTING;
-			if (commit->object.parsed)
-				mark_parents_uninteresting(commit);
-		}
-		/* treat root commit as boundary */
-		if (!commit->parents && !show_root)
-			commit->object.flags |= UNINTERESTING;
-
-		/* Take responsibility for the remaining entries */
-		for (ent = sb->ent; ent; ent = ent->next)
-			if (!cmp_suspect(ent->suspect, suspect))
-				ent->guilty = 1;
-		origin_decref(suspect);
-
-		if (DEBUG) /* sanity */
-			sanity_check_refcnt(sb);
-	}
-}
-
-static const char *format_time(unsigned long time, const char *tz_str,
-			       int show_raw_time)
-{
-	static char time_buf[128];
-	time_t t = time;
-	int minutes, tz;
-	struct tm *tm;
-
-	if (show_raw_time) {
-		sprintf(time_buf, "%lu %s", time, tz_str);
-		return time_buf;
-	}
-
-	tz = atoi(tz_str);
-	minutes = tz < 0 ? -tz : tz;
-	minutes = (minutes / 100)*60 + (minutes % 100);
-	minutes = tz < 0 ? -minutes : minutes;
-	t = time + minutes * 60;
-	tm = gmtime(&t);
-
-	strftime(time_buf, sizeof(time_buf), "%Y-%m-%d %H:%M:%S ", tm);
-	strcat(time_buf, tz_str);
-	return time_buf;
-}
-
 struct commit_info
 {
 	char *author;
@@ -1245,6 +1182,105 @@ static void get_commit_info(struct commit *commit,
 	summary_buf[len] = 0;
 }
 
+static void found_guilty_entry(struct blame_entry *ent)
+{
+	if (ent->guilty)
+		return;
+	ent->guilty = 1;
+	if (incremental) {
+		struct origin *suspect = ent->suspect;
+
+		printf("%s %d %d %d\n",
+		       sha1_to_hex(suspect->commit->object.sha1),
+		       ent->s_lno + 1, ent->lno + 1, ent->num_lines);
+		if (!(suspect->commit->object.flags & METAINFO_SHOWN)) {
+			struct commit_info ci;
+			suspect->commit->object.flags |= METAINFO_SHOWN;
+			get_commit_info(suspect->commit, &ci, 1);
+			printf("author %s\n", ci.author);
+			printf("author-mail %s\n", ci.author_mail);
+			printf("author-time %lu\n", ci.author_time);
+			printf("author-tz %s\n", ci.author_tz);
+			printf("committer %s\n", ci.committer);
+			printf("committer-mail %s\n", ci.committer_mail);
+			printf("committer-time %lu\n", ci.committer_time);
+			printf("committer-tz %s\n", ci.committer_tz);
+			printf("summary %s\n", ci.summary);
+			if (suspect->commit->object.flags & UNINTERESTING)
+				printf("boundary\n");
+		}
+		printf("filename ");
+		write_name_quoted(NULL, 0, suspect->path, 1, stdout);
+		putchar('\n');
+	}
+}
+
+static void assign_blame(struct scoreboard *sb, struct rev_info *revs, int opt)
+{
+	while (1) {
+		struct blame_entry *ent;
+		struct commit *commit;
+		struct origin *suspect = NULL;
+
+		/* find one suspect to break down */
+		for (ent = sb->ent; !suspect && ent; ent = ent->next)
+			if (!ent->guilty)
+				suspect = ent->suspect;
+		if (!suspect)
+			return; /* all done */
+
+		origin_incref(suspect);
+		commit = suspect->commit;
+		if (!commit->object.parsed)
+			parse_commit(commit);
+		if (!(commit->object.flags & UNINTERESTING) &&
+		    !(revs->max_age != -1 && commit->date  < revs->max_age))
+			pass_blame(sb, suspect, opt);
+		else {
+			commit->object.flags |= UNINTERESTING;
+			if (commit->object.parsed)
+				mark_parents_uninteresting(commit);
+		}
+		/* treat root commit as boundary */
+		if (!commit->parents && !show_root)
+			commit->object.flags |= UNINTERESTING;
+
+		/* Take responsibility for the remaining entries */
+		for (ent = sb->ent; ent; ent = ent->next)
+			if (!cmp_suspect(ent->suspect, suspect))
+				found_guilty_entry(ent);
+		origin_decref(suspect);
+
+		if (DEBUG) /* sanity */
+			sanity_check_refcnt(sb);
+	}
+}
+
+static const char *format_time(unsigned long time, const char *tz_str,
+			       int show_raw_time)
+{
+	static char time_buf[128];
+	time_t t = time;
+	int minutes, tz;
+	struct tm *tm;
+
+	if (show_raw_time) {
+		sprintf(time_buf, "%lu %s", time, tz_str);
+		return time_buf;
+	}
+
+	tz = atoi(tz_str);
+	minutes = tz < 0 ? -tz : tz;
+	minutes = (minutes / 100)*60 + (minutes % 100);
+	minutes = tz < 0 ? -minutes : minutes;
+	t = time + minutes * 60;
+	tm = gmtime(&t);
+
+	strftime(time_buf, sizeof(time_buf), "%Y-%m-%d %H:%M:%S ", tm);
+	strcat(time_buf, tz_str);
+	return time_buf;
+}
+
 #define OUTPUT_ANNOTATE_COMPAT	001
 #define OUTPUT_LONG_OBJECT_NAME	002
 #define OUTPUT_RAW_TIMESTAMP	004
@@ -1717,6 +1753,8 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 				die("More than one '-L n,m' option given");
 			bottomtop = arg;
 		}
+		else if (!strcmp("--incremental", arg))
+			incremental = 1;
 		else if (!strcmp("--score-debug", arg))
 			output_option |= OUTPUT_SHOW_SCORE;
 		else if (!strcmp("-f", arg) ||
@@ -1907,6 +1945,9 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 
 	assign_blame(&sb, &revs, opt);
 
+	if (incremental)
+		return 0;
+
 	coalesce(&sb);
 
 	if (!(output_option & OUTPUT_PORCELAIN))