graph API: don't print branch lines for uninteresting merge parents

Previously, the graphing code printed lines coming out of a merge commit
for all of its parents, even if some of them were uninteresting.  Now it
only prints lines for interesting commits.

For example, for a merge commit where only the first parent is
interesting, the code now prints:

  *  merge commit
  *  interesting child

instead of:

  M  merge commit
  |\
  *  interesting child

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 400f0147bfc38cff0127891874d0477673440f8f..add7e4477dfeb5715a13069d233365c8d2dce2c3 100644 (file)
--- a/graph.c
+++ b/graph.c
@@ -55,9 +55,11 @@ struct git_graph {
         */
        struct commit *commit;
        /*
-        * The number of parents this commit has.
-        * (Stored so we don't have to walk over them each time we need
-        * this number)
+        * The number of interesting parents that this commit has.
+        *
+        * Note that this is not the same as the actual number of parents.
+        * This count excludes parents that won't be printed in the graph
+        * output, as determined by graph_is_interesting().
         */
        int num_parents;
        /*
@@ -180,6 +182,18 @@ static void graph_ensure_capacity(struct git_graph *graph, int num_columns)
                                      sizeof(int) * 2 * graph->column_capacity);
 }
 
+/*
+ * Returns 1 if the commit will be printed in the graph output,
+ * and 0 otherwise.
+ */
+static int graph_is_interesting(struct commit *commit)
+{
+       /*
+        * Uninteresting and pruned commits won't be printed
+        */
+       return (commit->object.flags & (UNINTERESTING | TREESAME)) ? 0 : 1;
+}
+
 static void graph_insert_into_new_columns(struct git_graph *graph,
                                          struct commit *commit,
                                          int *mapping_index)
@@ -187,13 +201,10 @@ static void graph_insert_into_new_columns(struct git_graph *graph,
        int i;
 
        /*
-        * Ignore uinteresting and pruned commits
+        * Ignore uinteresting commits
         */
-       if (commit->object.flags & (UNINTERESTING | TREESAME))
-       {
-               *mapping_index += 2;
+       if (!graph_is_interesting(commit))
                return;
-       }
 
        /*
         * If the commit is already in the new_columns list, we don't need to
@@ -231,8 +242,8 @@ static void graph_update_width(struct git_graph *graph,
        int max_cols = graph->num_columns + graph->num_parents;
 
        /*
-        * Even if the current commit has no parents, it still takes up a
-        * column for itself.
+        * Even if the current commit has no parents to be printed, it
+        * still takes up a column for itself.
         */
        if (graph->num_parents < 1)
                max_cols++;
@@ -316,6 +327,7 @@ static void graph_update_columns(struct git_graph *graph)
                }
 
                if (col_commit == graph->commit) {
+                       int old_mapping_idx = mapping_idx;
                        seen_this = 1;
                        for (parent = graph->commit->parents;
                             parent;
@@ -324,6 +336,14 @@ static void graph_update_columns(struct git_graph *graph)
                                                              parent->item,
                                                              &mapping_idx);
                        }
+                       /*
+                        * We always need to increment mapping_idx by at
+                        * least 2, even if it has no interesting parents.
+                        * The current commit always takes up at least 2
+                        * spaces.
+                        */
+                       if (mapping_idx == old_mapping_idx)
+                               mapping_idx += 2;
                } else {
                        graph_insert_into_new_columns(graph, col_commit,
                                                      &mapping_idx);
@@ -353,11 +373,13 @@ void graph_update(struct git_graph *graph, struct commit *commit)
        graph->commit = commit;
 
        /*
-        * Count how many parents this commit has
+        * Count how many interesting parents this commit has
         */
        graph->num_parents = 0;
-       for (parent = commit->parents; parent; parent = parent->next)
-               graph->num_parents++;
+       for (parent = commit->parents; parent; parent = parent->next) {
+               if (graph_is_interesting(parent->item))
+                       graph->num_parents++;
+       }
 
        /*
         * Call graph_update_columns() to update
@@ -543,6 +565,15 @@ 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
+                        * parent, print 'M' to indicate that it is a
+                        * merge.  Otherwise, print '*'.
+                        *
+                        * Note that even if this is actually a merge
+                        * commit, we still print '*' if less than 2 of its
+                        * parents are interesting.
+                        */
                        if (graph->num_parents > 1)
                                strbuf_addch(sb, 'M');
                        else