graph: helper functions for printing commit header

The idea here is to make it possible to print something
right _before_ a commit in the graph. It's a bit ugly, but
it seems to mostly work (see the next commit for some
oddness).

Signed-off-by: Jeff King <[email protected]>

Author: peff

graph.c

@@ -1395,7 +1395,7 @@ int graph_is_commit_finished(struct git_graph const *graph)
 	return (graph->state == GRAPH_PADDING);
 }
 
-void graph_show_commit(struct git_graph *graph)
+static void graph_show_commit_1(struct git_graph *graph, int only_pre)
 {
 	struct strbuf msgbuf = STRBUF_INIT;
 	int shown_commit_line = 0;
@@ -1416,6 +1416,8 @@ void graph_show_commit(struct git_graph *graph)
 	}
 
 	while (!shown_commit_line && !graph_is_commit_finished(graph)) {
+		if (only_pre && graph->state == GRAPH_COMMIT)
+			break;
 		shown_commit_line = graph_next_line(graph, &msgbuf);
 		fwrite(msgbuf.buf, sizeof(char), msgbuf.len,
 			graph->revs->diffopt.file);
@@ -1429,6 +1431,16 @@ void graph_show_commit(struct git_graph *graph)
 	strbuf_release(&msgbuf);
 }
 
+void graph_show_precommit(struct git_graph *graph)
+{
+	graph_show_commit_1(graph, 1);
+}
+
+void graph_show_commit(struct git_graph *graph)
+{
+	graph_show_commit_1(graph, 0);
+}
+
 void graph_show_oneline(struct git_graph *graph)
 {
 	struct strbuf msgbuf = STRBUF_INIT;

graph.h

@@ -218,6 +218,12 @@ int graph_width(struct git_graph *graph);
  */
 void graph_show_commit(struct git_graph *graph);
 
+/*
+ * Same as graph_show_commit, but stop just _before_ printing
+ * the actual commit line.
+ */
+void graph_show_precommit(struct git_graph *graph);
+
 /*
  * If the graph is non-NULL, print one line of the history graph to stdout.
  * Does not print a terminating newline on the last line.