log --graph --left-right: show left/right information in place of '*'

With the --graph option, the graph already outputs 'o' instead of '*'
for boundary commits.  Make it emit '<' or '>' when --left-right is
specified.

(This change also disables the '^' prefix for UNINTERESTING commits.
The graph code currently doesn't print anything special for these
commits, since it assumes no UNINTERESTING, non-BOUNDARY commits are
displayed.  This is potentially a bug if UNINTERESTING non-BOUNDARY
commits can actually be displayed via some code path.)

[jc: squashed the left-right change from Dscho and Adam's fixup into one]

Signed-off-by: Adam Simpkins <adam@adamsimpkins.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/technical/api-history-graph.txt

@@ -115,7 +115,7 @@ Sample usage
 
 ------------
 struct commit *commit;
-struct git_graph *graph = graph_init();
+struct git_graph *graph = graph_init(opts);
 
 while ((commit = get_revision(opts)) != NULL) {
 	graph_update(graph, commit);

builtin-rev-list.c

@@ -65,6 +65,8 @@ static void show_commit(struct commit *commit)
 		printf("%lu ", commit->date);
 	if (header_prefix)
 		fputs(header_prefix, stdout);
+
+	if (!revs.graph) {
 		if (commit->object.flags & BOUNDARY)
 			putchar('-');
 		else if (commit->object.flags & UNINTERESTING)
@@ -75,6 +77,7 @@ static void show_commit(struct commit *commit)
 			else
 				putchar('>');
 		}
+	}
 	if (revs.abbrev_commit && revs.abbrev)
 		fputs(find_unique_abbrev(commit->object.sha1, revs.abbrev),
 		      stdout);

graph.c

@@ -54,6 +54,8 @@ struct git_graph {
 	 * The commit currently being processed
 	 */
 	struct commit *commit;
+	/* The rev-info used for the current traversal */
+	struct rev_info *revs;
 	/*
 	 * The number of interesting parents that this commit has.
 	 *
@@ -127,10 +129,11 @@ struct git_graph {
 	int *new_mapping;
 };
 
-struct git_graph *graph_init(void)
+struct git_graph *graph_init(struct rev_info *opt)
 {
 	struct git_graph *graph = xmalloc(sizeof(struct git_graph));
 	graph->commit = NULL;
+	graph->revs = opt;
 	graph->num_parents = 0;
 	graph->expansion_row = 0;
 	graph->state = GRAPH_PADDING;
@@ -565,16 +568,13 @@ void graph_output_commit_line(struct git_graph *graph, struct strbuf *sb)
 
 		if (col_commit == graph->commit) {
 			seen_this = 1;
-			/*
+
-			 * If the commit has more than 1 interesting
+			if (graph->revs && graph->revs->left_right) {
-			 * parent, print 'M' to indicate that it is a
+				if (graph->commit->object.flags & SYMMETRIC_LEFT)
-			 * merge.  Otherwise, print '*'.
+					strbuf_addch(sb, '<');
-			 *
+				else
-			 * Note that even if this is actually a merge
+					strbuf_addch(sb, '>');
-			 * commit, we still print '*' if less than 2 of its
+			} else if (graph->num_parents > 1)
-			 * parents are interesting.
-			 */
-			if (graph->num_parents > 1)
 				strbuf_addch(sb, 'M');
 			else
 				strbuf_addch(sb, '*');

graph.h

@@ -8,7 +8,7 @@ struct git_graph;
  * Create a new struct git_graph.
  * The graph should be freed with graph_release() when no longer needed.
  */
-struct git_graph *graph_init();
+struct git_graph *graph_init(struct rev_info *opt);
 
 /*
  * Destroy a struct git_graph and free associated memory.

log-tree.c

@@ -228,6 +228,7 @@ void show_log(struct rev_info *opt)
 	if (!opt->verbose_header) {
 		graph_show_commit(opt->graph);
 
+		if (!opt->graph) {
 			if (commit->object.flags & BOUNDARY)
 				putchar('-');
 			else if (commit->object.flags & UNINTERESTING)
@@ -238,6 +239,7 @@ void show_log(struct rev_info *opt)
 				else
 					putchar('>');
 			}
+		}
 		fputs(diff_unique_abbrev(commit->object.sha1, abbrev_commit), stdout);
 		if (opt->print_parents)
 			show_parents(commit, abbrev_commit);
@@ -293,6 +295,8 @@ void show_log(struct rev_info *opt)
 		fputs(diff_get_color_opt(&opt->diffopt, DIFF_COMMIT), stdout);
 		if (opt->commit_format != CMIT_FMT_ONELINE)
 			fputs("commit ", stdout);
+
+		if (!opt->graph) {
 			if (commit->object.flags & BOUNDARY)
 				putchar('-');
 			else if (commit->object.flags & UNINTERESTING)
@@ -303,6 +307,7 @@ void show_log(struct rev_info *opt)
 				else
 					putchar('>');
 			}
+		}
 		fputs(diff_unique_abbrev(commit->object.sha1, abbrev_commit),
 		      stdout);
 		if (opt->print_parents)

revision.c

@@ -1205,7 +1205,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 			if (!prefixcmp(arg, "--graph")) {
 				revs->topo_order = 1;
 				revs->rewrite_parents = 1;
-				revs->graph = graph_init();
+				revs->graph = graph_init(revs);
 				continue;
 			}
 			if (!strcmp(arg, "--root")) {