Merge branch 'ac/graph-horizontal-line'

* ac/graph-horizontal-line:
  graph API: Use horizontal lines for more compact graphs

diff --combined graph.c
index 06fbeb6c2416d0c1c5fd7df1a12924656592cdc3,47bce05c987e04ac7a1617867ff9aab896330c47..f8d7a5c0f6d17538a72b75e8de9dd092829a0262
--- 1/graph.c
--- 2/graph.c
+++ b/graph.c
@@@ -35,7 -35,7 +35,7 @@@ static void graph_padding_line(struct g
   * newline.  A new graph line will not be printed after the final newline.
   * If the strbuf is empty, no output will be printed.
   *
 - * Since the first line will not include the graph ouput, the caller is
 + * Since the first line will not include the graph output, the caller is
   * responsible for printing this line's graph (perhaps via
   * graph_show_commit() or graph_show_oneline()) before calling
   * graph_show_strbuf().
@@@ -47,20 -47,6 +47,6 @@@ static void graph_show_strbuf(struct gi
   * - Limit the number of columns, similar to the way gitk does.
   *   If we reach more than a specified number of columns, omit
   *   sections of some columns.
-  *
-  * - The output during the GRAPH_PRE_COMMIT and GRAPH_COLLAPSING states
-  *   could be made more compact by printing horizontal lines, instead of
-  *   long diagonal lines.  For example, during collapsing, something like
-  *   this:          instead of this:
-  *   | | | | |      | | | | |
-  *   | |_|_|/       | | | |/
-  *   |/| | |        | | |/|
-  *   | | | |        | |/| |
-  *                  |/| | |
-  *                  | | | |
-  *
-  *   If there are several parallel diagonal lines, they will need to be
-  *   replaced with horizontal lines on subsequent rows.
   */
  
  struct column {
@@@ -727,8 -713,8 +713,8 @@@ static void graph_output_pre_commit_lin
                if (col->commit == graph->commit) {
                        seen_this = 1;
                        strbuf_write_column(sb, col, '|');
 -                      strbuf_addf(sb, " %*s", graph->expansion_row, "");
 -                      chars_written += 2 + graph->expansion_row;
 +                      strbuf_addf(sb, "%*s", graph->expansion_row, "");
 +                      chars_written += 1 + graph->expansion_row;
                } else if (seen_this && (graph->expansion_row == 0)) {
                        /*
                         * This is the first line of the pre-commit output.
@@@ -852,7 -838,7 +838,7 @@@ static void graph_output_commit_line(st
                        graph_output_commit_char(graph, sb);
                        chars_written++;
  
 -                      if (graph->num_parents > 3)
 +                      if (graph->num_parents > 2)
                                chars_written += graph_draw_octopus_merge(graph,
                                                                          sb);
                } else if (seen_this && (graph->num_parents > 2)) {
@@@ -982,6 -968,9 +968,9 @@@ static void graph_output_collapsing_lin
  {
        int i;
        int *tmp_mapping;
+       short used_horizontal = 0;
+       int horizontal_edge = -1;
+       int horizontal_edge_target = -1;
  
        /*
         * Clear out the new_mapping array
@@@ -1019,6 -1008,23 +1008,23 @@@
                         * Move to the left by one
                         */
                        graph->new_mapping[i - 1] = target;
+                       /*
+                        * If there isn't already an edge moving horizontally
+                        * select this one.
+                        */
+                       if (horizontal_edge == -1) {
+                               int j;
+                               horizontal_edge = i;
+                               horizontal_edge_target = target;
+                               /*
+                                * The variable target is the index of the graph
+                                * column, and therefore target*2+3 is the
+                                * actual screen column of the first horizontal
+                                * line.
+                                */
+                               for (j = (target * 2)+3; j < (i - 2); j += 2)
+                                       graph->new_mapping[j] = target;
+                       }
                } else if (graph->new_mapping[i - 1] == target) {
                        /*
                         * There is a branch line to our left
@@@ -1039,10 -1045,21 +1045,21 @@@
                         *
                         * The space just to the left of this
                         * branch should always be empty.
+                        *
+                        * The branch to the left of that space
+                        * should be our eventual target.
                         */
                        assert(graph->new_mapping[i - 1] > target);
                        assert(graph->new_mapping[i - 2] < 0);
+                       assert(graph->new_mapping[i - 3] == target);
                        graph->new_mapping[i - 2] = target;
+                       /*
+                        * Mark this branch as the horizontal edge to
+                        * prevent any other edges from moving
+                        * horizontally.
+                        */
+                       if (horizontal_edge == -1)
+                               horizontal_edge = i;
                }
        }
  
@@@ -1061,8 -1078,23 +1078,23 @@@
                        strbuf_addch(sb, ' ');
                else if (target * 2 == i)
                        strbuf_write_column(sb, &graph->new_columns[target], '|');
-               else
+               else if (target == horizontal_edge_target &&
+                        i != horizontal_edge - 1) {
+                               /*
+                                * Set the mappings for all but the
+                                * first segment to -1 so that they
+                                * won't continue into the next line.
+                                */
+                               if (i != (target * 2)+3)
+                                       graph->new_mapping[i] = -1;
+                               used_horizontal = 1;
+                       strbuf_write_column(sb, &graph->new_columns[target], '_');
+               } else {
+                       if (used_horizontal && i < horizontal_edge)
+                               graph->new_mapping[i] = -1;
                        strbuf_write_column(sb, &graph->new_columns[target], '/');
+ 
+               }
        }
  
        graph_pad_horizontally(graph, sb, graph->mapping_size);

diff --combined t/t4202-log.sh
index 64502e2be762a82b65a72af6847d5a3b79303d45,a3b0cb88d182f70d91b8e7a555e767e3b7f78837..aad3894ad4c542d4ab894c2d57a035a89eb88258
--- 1/t/t4202-log.sh
--- 2/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@@ -284,36 -284,10 +284,36 @@@ test_expect_success 'set up more tangle
        git merge master~3 &&
        git merge side~1 &&
        git checkout master &&
 -      git merge tangle
 +      git merge tangle &&
 +      git checkout -b reach &&
 +      test_commit reach &&
 +      git checkout master &&
 +      git checkout -b octopus-a &&
 +      test_commit octopus-a &&
 +      git checkout master &&
 +      git checkout -b octopus-b &&
 +      test_commit octopus-b &&
 +      git checkout master &&
 +      test_commit seventh &&
 +      git merge octopus-a octopus-b
 +      git merge reach
  '
  
  cat > expect <<\EOF
 +*   Merge branch 'reach'
 +|\
 +| \
 +|  \
 +*-. \   Merge branches 'octopus-a' and 'octopus-b'
 +|\ \ \
 +* | | | seventh
 +| | * | octopus-b
 +| |/ /
 +|/| |
 +| * | octopus-a
 +|/ /
 +| * reach
 +|/
  *   Merge branch 'tangle'
  |\
  | *   Merge branch 'side' (early part) into tangle
@@@ -324,14 -298,12 +324,12 @@@
  * | | |   Merge branch 'side'
  |\ \ \ \
  | * | | | side-2
- | | | |/
- | | |/|
+ | | |_|/
  | |/| |
  | * | | side-1
  * | | | Second
  * | | | sixth
- | | |/
- | |/|
+ | |_|/
  |/| |
  * | | fifth
  * | | fourth