From: James Coglan <jcog...@gmail.com>

Currently, when we display a merge whose first parent is already present
in a column to the left of the merge commit, we display the first parent
as a vertical pipe `|` in the GRAPH_POST_MERGE line and then immediately
enter the GRAPH_COLLAPSING state. The first-parent line tracks to the
left and all the other parent lines follow it; this creates a "kink" in
those lines:

        | *---.
        | |\ \ \
        |/ / / /
        | | | *

This change tidies the display of such commits such that if the first
parent appears to the left of the merge, we render it as a `/` and the
second parent as a `|`. This reduces the horizontal and vertical space
needed to render the merge, and makes the resulting lines easier to
read.

        | *-.
        |/|\ \
        | | | *

If the first parent is separated from the merge by several columns, a
horizontal line is drawn in a similar manner to how the GRAPH_COLLAPSING
state displays the line.

        | | | *-.
        | |_|/|\ \
        |/| | | | *

This effect is applied to both "normal" two-parent merges, and to
octopus merges. It also reduces the vertical space needed for pre-commit
lines, as the merge occupies one less column than usual.

        Before:         After:

        | *             | *
        | |\            | |\
        | | \           | * \
        | |  \          |/|\ \
        | *-. \
        | |\ \ \

Signed-off-by: James Coglan <jcog...@gmail.com>
---
 graph.c                      | 125 +++++++++++++++++++++++++++--------
 t/t4214-log-graph-octopus.sh |  20 +++---
 t/t4215-log-skewed-merges.sh |  45 +++++++++++--
 3 files changed, 144 insertions(+), 46 deletions(-)

diff --git a/graph.c b/graph.c
index bd7403065e..e37127f5ab 100644
--- a/graph.c
+++ b/graph.c
@@ -202,6 +202,20 @@ struct git_graph {
         * previous commit.
         */
        int prev_commit_index;
+       /*
+        * Which layout variant to use to display merge commits. If the
+        * commit's first parent is known to be in a column to the left of the
+        * merge, then this value is 0 and we use the layout on the left.
+        * Otherwise, the value is 1 and the layout on the right is used. This
+        * field tells us how many columns the first parent occupies.
+        *
+        *              0)                      1)
+        *
+        *              | | | *-.               | | *---.
+        *              | |_|/|\ \              | | |\ \ \
+        *              |/| | | | |             | | | | | *
+        */
+       int merge_layout;
        /*
         * The maximum number of columns that can be stored in the columns
         * and new_columns arrays.  This is also half the number of entries
@@ -313,6 +327,7 @@ struct git_graph *graph_init(struct rev_info *opt)
        graph->prev_state = GRAPH_PADDING;
        graph->commit_index = 0;
        graph->prev_commit_index = 0;
+       graph->merge_layout = 0;
        graph->num_columns = 0;
        graph->num_new_columns = 0;
        graph->mapping_size = 0;
@@ -472,9 +487,11 @@ static int graph_find_new_column_by_commit(struct 
git_graph *graph,
 }
 
 static void graph_insert_into_new_columns(struct git_graph *graph,
-                                         struct commit *commit)
+                                         struct commit *commit,
+                                         int idx)
 {
        int i = graph_find_new_column_by_commit(graph, commit);
+       int mapping_idx;
 
        /*
         * If the commit is not already in the new_columns array, then add it
@@ -486,8 +503,26 @@ static void graph_insert_into_new_columns(struct git_graph 
*graph,
                graph->new_columns[i].color = graph_find_commit_color(graph, 
commit);
        }
 
-       graph->mapping[graph->width] = i;
-       graph->width += 2;
+       if (graph->num_parents > 1 && idx > -1 && graph->merge_layout == -1) {
+               /*
+                * If this is the first parent of a merge, choose a layout for
+                * the merge line based on whether the parent appears in a
+                * column to the left of the merge
+                */
+               int dist, shift;
+
+               dist = idx - i;
+               shift = (dist > 1) ? 2 * dist - 3 : 1;
+
+               graph->merge_layout = (dist > 0) ? 0 : 1;
+               mapping_idx = graph->width + (graph->merge_layout - 1) * shift;
+               graph->width += 2 * graph->merge_layout;
+       } else {
+               mapping_idx = graph->width;
+               graph->width += 2;
+       }
+
+       graph->mapping[mapping_idx] = i;
 }
 
 static void graph_update_columns(struct git_graph *graph)
@@ -553,6 +588,7 @@ static void graph_update_columns(struct git_graph *graph)
                if (col_commit == graph->commit) {
                        seen_this = 1;
                        graph->commit_index = i;
+                       graph->merge_layout = -1;
                        for (parent = first_interesting_parent(graph);
                             parent;
                             parent = next_interesting_parent(graph, parent)) {
@@ -565,7 +601,7 @@ static void graph_update_columns(struct git_graph *graph)
                                    !is_commit_in_columns) {
                                        graph_increment_column_color(graph);
                                }
-                               graph_insert_into_new_columns(graph, 
parent->item);
+                               graph_insert_into_new_columns(graph, 
parent->item, i);
                        }
                        /*
                         * We always need to increment graph->width by at
@@ -576,7 +612,7 @@ static void graph_update_columns(struct git_graph *graph)
                        if (graph->num_parents == 0)
                                graph->width += 2;
                } else {
-                       graph_insert_into_new_columns(graph, col_commit);
+                       graph_insert_into_new_columns(graph, col_commit, -1);
                }
        }
 
@@ -588,10 +624,36 @@ static void graph_update_columns(struct git_graph *graph)
                graph->mapping_size--;
 }
 
+static int graph_num_expansion_rows(struct git_graph *graph)
+{
+       /*
+        * Normally, we need two expansion rows for each dashed parent line from
+        * an octopus merge:
+        *
+        *              | *
+        *              | |\
+        *              | | \
+        *              | |  \
+        *              | *-. \
+        *              | |\ \ \
+        *
+        * If the merge is skewed to the left, then its parents occupy one less
+        * column, and we don't need as many expansion rows to route around it;
+        * in some cases that means we don't need any expansion rows at all:
+        *
+        *              | *
+        *              | |\
+        *              | * \
+        *              |/|\ \
+        */
+       return (graph->num_parents + graph->merge_layout - 3) * 2;
+}
+
 static int graph_needs_pre_commit_line(struct git_graph *graph)
 {
        return graph->num_parents >= 3 &&
-              graph->commit_index < (graph->num_columns - 1);
+              graph->commit_index < (graph->num_columns - 1) &&
+              graph->expansion_row < graph_num_expansion_rows(graph);
 }
 
 void graph_update(struct git_graph *graph, struct commit *commit)
@@ -728,7 +790,6 @@ static void graph_output_skip_line(struct git_graph *graph, 
struct graph_line *l
 static void graph_output_pre_commit_line(struct git_graph *graph,
                                         struct graph_line *line)
 {
-       int num_expansion_rows;
        int i, seen_this;
 
        /*
@@ -739,14 +800,13 @@ static void graph_output_pre_commit_line(struct git_graph 
*graph,
         * We need 2 extra rows for every parent over 2.
         */
        assert(graph->num_parents >= 3);
-       num_expansion_rows = (graph->num_parents - 2) * 2;
 
        /*
         * graph->expansion_row tracks the current expansion row we are on.
         * It should be in the range [0, num_expansion_rows - 1]
         */
        assert(0 <= graph->expansion_row &&
-              graph->expansion_row < num_expansion_rows);
+              graph->expansion_row < graph_num_expansion_rows(graph));
 
        /*
         * Output the row
@@ -786,7 +846,7 @@ static void graph_output_pre_commit_line(struct git_graph 
*graph,
         * and move to state GRAPH_COMMIT if necessary
         */
        graph->expansion_row++;
-       if (graph->expansion_row >= num_expansion_rows)
+       if (!graph_needs_pre_commit_line(graph))
                graph_update_state(graph, GRAPH_COMMIT);
 }
 
@@ -824,7 +884,7 @@ static void graph_draw_octopus_merge(struct git_graph 
*graph, struct graph_line
         * x 0 1 2 3
         *
         */
-       const int dashless_parents = 2;
+       const int dashless_parents = 3 - graph->merge_layout;
        int dashful_parents = graph->num_parents - dashless_parents;
 
        /*
@@ -832,9 +892,9 @@ static void graph_draw_octopus_merge(struct git_graph 
*graph, struct graph_line
         * above) but sometimes the first parent goes into an existing column,
         * like this:
         *
-        * | *---.
-        * | |\ \ \
-        * |/ / / /
+        * | *-.
+        * |/|\ \
+        * | | | |
         * x 0 1 2
         *
         * In which case the number of parents will be one greater than the
@@ -925,10 +985,15 @@ static void graph_output_commit_line(struct git_graph 
*graph, struct graph_line
                graph_update_state(graph, GRAPH_COLLAPSING);
 }
 
+const char merge_chars[] = {'/', '|', '\\'};
+
 static void graph_output_post_merge_line(struct git_graph *graph, struct 
graph_line *line)
 {
        int seen_this = 0;
-       int i, j;
+       int i;
+
+       struct commit_list *first_parent = first_interesting_parent(graph);
+       int seen_parent = 0;
 
        /*
         * Output the post-merge row
@@ -951,30 +1016,34 @@ static void graph_output_post_merge_line(struct 
git_graph *graph, struct graph_l
                         * new_columns and use those to format the
                         * edges.
                         */
-                       struct commit_list *parents = NULL;
+                       struct commit_list *parents = first_parent;
                        int par_column;
+                       int idx = graph->merge_layout;
+                       char c;
                        seen_this = 1;
-                       parents = first_interesting_parent(graph);
-                       assert(parents);
-                       par_column = graph_find_new_column_by_commit(graph, 
parents->item);
-                       assert(par_column >= 0);
-
-                       graph_line_write_column(line, 
&graph->new_columns[par_column], '|');
-                       for (j = 0; j < graph->num_parents - 1; j++) {
-                               parents = next_interesting_parent(graph, 
parents);
-                               assert(parents);
+
+                       for (; parents; parents = 
next_interesting_parent(graph, parents)) {
                                par_column = 
graph_find_new_column_by_commit(graph, parents->item);
                                assert(par_column >= 0);
-                               graph_line_write_column(line, 
&graph->new_columns[par_column], '\\');
-                               graph_line_addch(line, ' ');
+
+                               c = merge_chars[idx];
+                               graph_line_write_column(line, 
&graph->new_columns[par_column], c);
+                               if (idx == 2)
+                                       graph_line_addch(line, ' ');
+                               else
+                                       idx++;
                        }
                } else if (seen_this) {
                        graph_line_write_column(line, col, '\\');
                        graph_line_addch(line, ' ');
                } else {
                        graph_line_write_column(line, col, '|');
-                       graph_line_addch(line, ' ');
+                       if (graph->merge_layout != 0 || i != 
graph->commit_index - 1)
+                               graph_line_addch(line, seen_parent ? '_' : ' ');
                }
+
+               if (col_commit == first_parent->item)
+                       seen_parent = 1;
        }
 
        /*
diff --git a/t/t4214-log-graph-octopus.sh b/t/t4214-log-graph-octopus.sh
index 3ae8e51e50..1b96276894 100755
--- a/t/t4214-log-graph-octopus.sh
+++ b/t/t4214-log-graph-octopus.sh
@@ -26,9 +26,8 @@ test_expect_success 'set up merge history' '
 test_expect_success 'log --graph with tricky octopus merge, no color' '
        cat >expect.uncolored <<-\EOF &&
        * left
-       | *---.   octopus-merge
-       | |\ \ \
-       |/ / / /
+       | *-.   octopus-merge
+       |/|\ \
        | | | * 4
        | | * | 3
        | | |/
@@ -47,9 +46,8 @@ test_expect_success 'log --graph with tricky octopus merge 
with colors' '
        test_config log.graphColors red,green,yellow,blue,magenta,cyan &&
        cat >expect.colors <<-\EOF &&
        * left
-       <RED>|<RESET> 
*<BLUE>-<RESET><BLUE>-<RESET><MAGENTA>-<RESET><MAGENTA>.<RESET>   octopus-merge
-       <RED>|<RESET> <RED>|<RESET><YELLOW>\<RESET> <BLUE>\<RESET> 
<MAGENTA>\<RESET>
-       <RED>|<RESET><RED>/<RESET> <YELLOW>/<RESET> <BLUE>/<RESET> 
<MAGENTA>/<RESET>
+       <RED>|<RESET> *<MAGENTA>-<RESET><MAGENTA>.<RESET>   octopus-merge
+       <RED>|<RESET><RED>/<RESET><YELLOW>|<RESET><BLUE>\<RESET> 
<MAGENTA>\<RESET>
        <RED>|<RESET> <YELLOW>|<RESET> <BLUE>|<RESET> * 4
        <RED>|<RESET> <YELLOW>|<RESET> * <MAGENTA>|<RESET> 3
        <RED>|<RESET> <YELLOW>|<RESET> <MAGENTA>|<RESET><MAGENTA>/<RESET>
@@ -147,9 +145,8 @@ test_expect_success 'log --graph with tricky octopus merge 
and its child, no col
        cat >expect.uncolored <<-\EOF &&
        * left
        | * after-merge
-       | *---.   octopus-merge
-       | |\ \ \
-       |/ / / /
+       | *-.   octopus-merge
+       |/|\ \
        | | | * 4
        | | * | 3
        | | |/
@@ -169,9 +166,8 @@ test_expect_failure 'log --graph with tricky octopus merge 
and its child with co
        cat >expect.colors <<-\EOF &&
        * left
        <RED>|<RESET> * after-merge
-       <RED>|<RESET> 
*<MAGENTA>-<RESET><MAGENTA>-<RESET><CYAN>-<RESET><CYAN>.<RESET>   octopus-merge
-       <RED>|<RESET> <RED>|<RESET><BLUE>\<RESET> <MAGENTA>\<RESET> 
<CYAN>\<RESET>
-       <RED>|<RESET><RED>/<RESET> <BLUE>/<RESET> <MAGENTA>/<RESET> 
<CYAN>/<RESET>
+       <RED>|<RESET> *<CYAN>-<RESET><CYAN>.<RESET>   octopus-merge
+       <RED>|<RESET><RED>/<RESET><BLUE>|<RESET><MAGENTA>\<RESET> <CYAN>\<RESET>
        <RED>|<RESET> <BLUE>|<RESET> <MAGENTA>|<RESET> * 4
        <RED>|<RESET> <BLUE>|<RESET> * <CYAN>|<RESET> 3
        <RED>|<RESET> <BLUE>|<RESET> <CYAN>|<RESET><CYAN>/<RESET>
diff --git a/t/t4215-log-skewed-merges.sh b/t/t4215-log-skewed-merges.sh
index 4582ba066a..dc187b5caf 100755
--- a/t/t4215-log-skewed-merges.sh
+++ b/t/t4215-log-skewed-merges.sh
@@ -11,12 +11,8 @@ test_expect_success 'log --graph with merge fusing with its 
left and right neigh
        | *   G
        | |\
        | | * F
-       | | |
-       | |  \
-       | *-. \   E
-       | |\ \ \
-       |/ / / /
-       | | | /
+       | * \   E
+       |/|\ \
        | | |/
        | | * D
        | * | C
@@ -40,4 +36,41 @@ test_expect_success 'log --graph with merge fusing with its 
left and right neigh
        test_cmp expect actual
 '
 
+test_expect_success 'log --graph with left-skewed merge' '
+       cat >expect <<-\EOF &&
+       *-----.   0_H
+       |\ \ \ \
+       | | | | * 0_G
+       | |_|_|/|
+       |/| | | |
+       | | | * \   0_F
+       | |_|/|\ \
+       |/| | | |/
+       | | | | * 0_E
+       | |_|_|/
+       |/| | |
+       | | * | 0_D
+       | | |/
+       | | * 0_C
+       | |/
+       |/|
+       | * 0_B
+       |/
+       * 0_A
+       EOF
+
+       git checkout --orphan 0_p && test_commit 0_A &&
+       git checkout -b 0_q 0_p && test_commit 0_B &&
+       git checkout -b 0_r 0_p &&
+       test_commit 0_C &&
+       test_commit 0_D &&
+       git checkout -b 0_s 0_p && test_commit 0_E &&
+       git checkout -b 0_t 0_p && git merge --no-ff 0_r^ 0_s -m 0_F &&
+       git checkout 0_p && git merge --no-ff 0_s -m 0_G &&
+       git checkout @^ && git merge --no-ff 0_q 0_r 0_t 0_p -m 0_H &&
+
+       git log --graph --pretty=tformat:%s | sed "s/ *$//" >actual &&
+       test_cmp expect actual
+'
+
 test_done
-- 
gitgitgadget

Reply via email to