graph API: fix "git log --graph --first-parent"

This change teaches the graph API that only the first parent of each
commit is interesting when "--first-parent" was specified.

This change also consolidates the graph parent walking logic into two
new internal functions, first_interesting_parent() and
next_interesting_parent().  A simpler fix would have been to simply
break at the end of the 2 existing for loops when
graph->revs->first_parent_only is set.  However, this change seems
nicer, especially if we ever need to add any new loops over the parent
list in the future.

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

diff --git a/graph.c b/graph.c
index edfab2d5b461f5bfd39d32fa843ee59841b4ce0a..283b13792d943e19ba2b68cf9705ada03dbadc94 100644 (file)
--- a/graph.c
+++ b/graph.c
@@ -237,18 +237,58 @@ static int graph_is_interesting(struct git_graph *graph, struct commit *commit)
        return (commit->object.flags & (UNINTERESTING | TREESAME)) ? 0 : 1;
 }
 
+static struct commit_list *next_interesting_parent(struct git_graph *graph,
+                                                  struct commit_list *orig)
+{
+       struct commit_list *list;
+
+       /*
+        * If revs->first_parent_only is set, only the first
+        * parent is interesting.  None of the others are.
+        */
+       if (graph->revs->first_parent_only)
+               return NULL;
+
+       /*
+        * Return the next interesting commit after orig
+        */
+       for (list = orig->next; list; list = list->next) {
+               if (graph_is_interesting(graph, list->item))
+                       return list;
+       }
+
+       return NULL;
+}
+
+static struct commit_list *first_interesting_parent(struct git_graph *graph)
+{
+       struct commit_list *parents = graph->commit->parents;
+
+       /*
+        * If this commit has no parents, ignore it
+        */
+       if (!parents)
+               return NULL;
+
+       /*
+        * If the first parent is interesting, return it
+        */
+       if (graph_is_interesting(graph, parents->item))
+               return parents;
+
+       /*
+        * Otherwise, call next_interesting_parent() to get
+        * the next interesting parent
+        */
+       return next_interesting_parent(graph, parents);
+}
+
 static void graph_insert_into_new_columns(struct git_graph *graph,
                                          struct commit *commit,
                                          int *mapping_index)
 {
        int i;
 
-       /*
-        * Ignore uinteresting commits
-        */
-       if (!graph_is_interesting(graph, commit))
-               return;
-
        /*
         * If the commit is already in the new_columns list, we don't need to
         * add it.  Just update the mapping correctly.
@@ -373,9 +413,9 @@ static void graph_update_columns(struct git_graph *graph)
                        int old_mapping_idx = mapping_idx;
                        seen_this = 1;
                        graph->commit_index = i;
-                       for (parent = graph->commit->parents;
+                       for (parent = first_interesting_parent(graph);
                             parent;
-                            parent = parent->next) {
+                            parent = next_interesting_parent(graph, parent)) {
                                graph_insert_into_new_columns(graph,
                                                              parent->item,
                                                              &mapping_idx);
@@ -420,9 +460,11 @@ void graph_update(struct git_graph *graph, struct commit *commit)
         * Count how many interesting parents this commit has
         */
        graph->num_parents = 0;
-       for (parent = commit->parents; parent; parent = parent->next) {
-               if (graph_is_interesting(graph, parent->item))
-                       graph->num_parents++;
+       for (parent = first_interesting_parent(graph);
+            parent;
+            parent = next_interesting_parent(graph, parent))
+       {
+               graph->num_parents++;
        }
 
        /*