graph: tidy up display of left-skewed merges
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 <jcoglan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
James Coglan committed
Oct 15, 2019 at 23:47 UTC
0f0f389f12029b1c3745f8ed7aacfe6b2fc7a6cc
3 files changed
+144
-46
graph.c
+97
-28
@@ -202,6 +202,20 @@ struct git_graph {
202
* previous commit.
203
*/
204
int prev_commit_index;
205
+ /*
206
+ * Which layout variant to use to display merge commits. If the
207
+ * commit's first parent is known to be in a column to the left of the
208
+ * merge, then this value is 0 and we use the layout on the left.
209
+ * Otherwise, the value is 1 and the layout on the right is used. This
210
+ * field tells us how many columns the first parent occupies.
211
+ *
212
+ * 0) 1)
213
+ *
214
+ * | | | *-. | | *---.
215
+ * | |_|/|\ \ | | |\ \ \
216
+ * |/| | | | | | | | | | *
217
+ */
218
+ int merge_layout;
219
/*
220
* The maximum number of columns that can be stored in the columns
221
* 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)
327
graph->prev_state = GRAPH_PADDING;
328
graph->commit_index = 0;
329
graph->prev_commit_index = 0;
330
+ graph->merge_layout = 0;
331
graph->num_columns = 0;
332
graph->num_new_columns = 0;
333
graph->mapping_size = 0;
@@ -472,9 +487,11 @@ static int graph_find_new_column_by_commit(struct git_graph *graph,
487
}
488
489
static void graph_insert_into_new_columns(struct git_graph *graph,
475
- struct commit *commit)
490
+ struct commit *commit,
491
+ int idx)
492
{
493
int i = graph_find_new_column_by_commit(graph, commit);
494
+ int mapping_idx;
495
496
/*
497
* 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,
503
graph->new_columns[i].color = graph_find_commit_color(graph, commit);
504
}
505
489
- graph->mapping[graph->width] = i;
490
- graph->width += 2;
506
+ if (graph->num_parents > 1 && idx > -1 && graph->merge_layout == -1) {
507
+ /*
508
+ * If this is the first parent of a merge, choose a layout for
509
+ * the merge line based on whether the parent appears in a
510
+ * column to the left of the merge
511
+ */
512
+ int dist, shift;
513
+
514
+ dist = idx - i;
515
+ shift = (dist > 1) ? 2 * dist - 3 : 1;
516
+
517
+ graph->merge_layout = (dist > 0) ? 0 : 1;
518
+ mapping_idx = graph->width + (graph->merge_layout - 1) * shift;
519
+ graph->width += 2 * graph->merge_layout;
520
+ } else {
521
+ mapping_idx = graph->width;
522
+ graph->width += 2;
523
+ }
524
+
525
+ graph->mapping[mapping_idx] = i;
526
}
527
528
static void graph_update_columns(struct git_graph *graph)
@@ -553,6 +588,7 @@ static void graph_update_columns(struct git_graph *graph)
588
if (col_commit == graph->commit) {
589
seen_this = 1;
590
graph->commit_index = i;
591
+ graph->merge_layout = -1;
592
for (parent = first_interesting_parent(graph);
593
parent;
594
parent = next_interesting_parent(graph, parent)) {
@@ -565,7 +601,7 @@ static void graph_update_columns(struct git_graph *graph)
601
!is_commit_in_columns) {
602
graph_increment_column_color(graph);
603
}
568
- graph_insert_into_new_columns(graph, parent->item);
604
+ graph_insert_into_new_columns(graph, parent->item, i);
605
}
606
/*
607
* We always need to increment graph->width by at
@@ -576,7 +612,7 @@ static void graph_update_columns(struct git_graph *graph)
612
if (graph->num_parents == 0)
613
graph->width += 2;
614
} else {
579
- graph_insert_into_new_columns(graph, col_commit);
615
+ graph_insert_into_new_columns(graph, col_commit, -1);
616
}
617
}
618
@@ -588,10 +624,36 @@ static void graph_update_columns(struct git_graph *graph)
624
graph->mapping_size--;
625
}
626
627
+static int graph_num_expansion_rows(struct git_graph *graph)
628
+{
629
+ /*
630
+ * Normally, we need two expansion rows for each dashed parent line from
631
+ * an octopus merge:
632
+ *
633
+ * | *
634
+ * | |\
635
+ * | | \
636
+ * | | \
637
+ * | *-. \
638
+ * | |\ \ \
639
+ *
640
+ * If the merge is skewed to the left, then its parents occupy one less
641
+ * column, and we don't need as many expansion rows to route around it;
642
+ * in some cases that means we don't need any expansion rows at all:
643
+ *
644
+ * | *
645
+ * | |\
646
+ * | * \
647
+ * |/|\ \
648
+ */
649
+ return (graph->num_parents + graph->merge_layout - 3) * 2;
650
+}
651
+
652
static int graph_needs_pre_commit_line(struct git_graph *graph)
653
{
654
return graph->num_parents >= 3 &&
594
- graph->commit_index < (graph->num_columns - 1);
655
+ graph->commit_index < (graph->num_columns - 1) &&
656
+ graph->expansion_row < graph_num_expansion_rows(graph);
657
}
658
659
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
790
static void graph_output_pre_commit_line(struct git_graph *graph,
791
struct graph_line *line)
792
{
731
- int num_expansion_rows;
793
int i, seen_this;
794
795
/*
@@ -739,14 +800,13 @@ static void graph_output_pre_commit_line(struct git_graph *graph,
800
* We need 2 extra rows for every parent over 2.
801
*/
802
assert(graph->num_parents >= 3);
742
- num_expansion_rows = (graph->num_parents - 2) * 2;
803
804
/*
805
* graph->expansion_row tracks the current expansion row we are on.
806
* It should be in the range [0, num_expansion_rows - 1]
807
*/
808
assert(0 <= graph->expansion_row &&
749
- graph->expansion_row < num_expansion_rows);
809
+ graph->expansion_row < graph_num_expansion_rows(graph));
810
811
/*
812
* Output the row
@@ -786,7 +846,7 @@ static void graph_output_pre_commit_line(struct git_graph *graph,
846
* and move to state GRAPH_COMMIT if necessary
847
*/
848
graph->expansion_row++;
789
- if (graph->expansion_row >= num_expansion_rows)
849
+ if (!graph_needs_pre_commit_line(graph))
850
graph_update_state(graph, GRAPH_COMMIT);
851
}
852
@@ -824,7 +884,7 @@ static void graph_draw_octopus_merge(struct git_graph *graph, struct graph_line
884
* x 0 1 2 3
885
*
886
*/
827
- const int dashless_parents = 2;
887
+ const int dashless_parents = 3 - graph->merge_layout;
888
int dashful_parents = graph->num_parents - dashless_parents;
889
890
/*
@@ -832,9 +892,9 @@ static void graph_draw_octopus_merge(struct git_graph *graph, struct graph_line
892
* above) but sometimes the first parent goes into an existing column,
893
* like this:
894
*
835
- * | *---.
836
- * | |\ \ \
837
- * |/ / / /
895
+ * | *-.
896
+ * |/|\ \
897
+ * | | | |
898
* x 0 1 2
899
*
900
* 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
985
graph_update_state(graph, GRAPH_COLLAPSING);
986
}
987
988
+const char merge_chars[] = {'/', '|', '\\'};
989
+
990
static void graph_output_post_merge_line(struct git_graph *graph, struct graph_line *line)
991
{
992
int seen_this = 0;
931
- int i, j;
993
+ int i;
994
+
995
+ struct commit_list *first_parent = first_interesting_parent(graph);
996
+ int seen_parent = 0;
997
998
/*
999
* Output the post-merge row
@@ -951,30 +1016,34 @@ static void graph_output_post_merge_line(struct git_graph *graph, struct graph_l
1016
* new_columns and use those to format the
1017
* edges.
1018
*/
954
- struct commit_list *parents = NULL;
1019
+ struct commit_list *parents = first_parent;
1020
int par_column;
1021
+ int idx = graph->merge_layout;
1022
+ char c;
1023
seen_this = 1;
957
- parents = first_interesting_parent(graph);
958
- assert(parents);
959
- par_column = graph_find_new_column_by_commit(graph, parents->item);
960
- assert(par_column >= 0);
961
-
962
- graph_line_write_column(line, &graph->new_columns[par_column], '|');
963
- for (j = 0; j < graph->num_parents - 1; j++) {
964
- parents = next_interesting_parent(graph, parents);
965
- assert(parents);
1024
+
1025
+ for (; parents; parents = next_interesting_parent(graph, parents)) {
1026
par_column = graph_find_new_column_by_commit(graph, parents->item);
1027
assert(par_column >= 0);
968
- graph_line_write_column(line, &graph->new_columns[par_column], '\\');
969
- graph_line_addch(line, ' ');
1028
+
1029
+ c = merge_chars[idx];
1030
+ graph_line_write_column(line, &graph->new_columns[par_column], c);
1031
+ if (idx == 2)
1032
+ graph_line_addch(line, ' ');
1033
+ else
1034
+ idx++;
1035
}
1036
} else if (seen_this) {
1037
graph_line_write_column(line, col, '\\');
1038
graph_line_addch(line, ' ');
1039
} else {
1040
graph_line_write_column(line, col, '|');
976
- graph_line_addch(line, ' ');
1041
+ if (graph->merge_layout != 0 || i != graph->commit_index - 1)
1042
+ graph_line_addch(line, seen_parent ? '_' : ' ');
1043
}
1044
+
1045
+ if (col_commit == first_parent->item)
1046
+ seen_parent = 1;
1047
}
1048
1049
/*
t/t4214-log-graph-octopus.sh
+8
-12
@@ -26,9 +26,8 @@ test_expect_success 'set up merge history' '
26
test_expect_success 'log --graph with tricky octopus merge, no color' '
27
cat >expect.uncolored <<-\EOF &&
28
* left
29
- | *---. octopus-merge
30
- | |\ \ \
31
- |/ / / /
29
+ | *-. octopus-merge
30
+ |/|\ \
31
| | | * 4
32
| | * | 3
33
| | |/
@@ -47,9 +46,8 @@ test_expect_success 'log --graph with tricky octopus merge with colors' '
46
test_config log.graphColors red,green,yellow,blue,magenta,cyan &&
47
cat >expect.colors <<-\EOF &&
48
* left
50
- <RED>|<RESET> *<BLUE>-<RESET><BLUE>-<RESET><MAGENTA>-<RESET><MAGENTA>.<RESET> octopus-merge
51
- <RED>|<RESET> <RED>|<RESET><YELLOW>\<RESET> <BLUE>\<RESET> <MAGENTA>\<RESET>
52
- <RED>|<RESET><RED>/<RESET> <YELLOW>/<RESET> <BLUE>/<RESET> <MAGENTA>/<RESET>
49
+ <RED>|<RESET> *<MAGENTA>-<RESET><MAGENTA>.<RESET> octopus-merge
50
+ <RED>|<RESET><RED>/<RESET><YELLOW>|<RESET><BLUE>\<RESET> <MAGENTA>\<RESET>
51
<RED>|<RESET> <YELLOW>|<RESET> <BLUE>|<RESET> * 4
52
<RED>|<RESET> <YELLOW>|<RESET> * <MAGENTA>|<RESET> 3
53
<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
145
cat >expect.uncolored <<-\EOF &&
146
* left
147
| * after-merge
150
- | *---. octopus-merge
151
- | |\ \ \
152
- |/ / / /
148
+ | *-. octopus-merge
149
+ |/|\ \
150
| | | * 4
151
| | * | 3
152
| | |/
@@ -169,9 +166,8 @@ test_expect_failure 'log --graph with tricky octopus merge and its child with co
166
cat >expect.colors <<-\EOF &&
167
* left
168
<RED>|<RESET> * after-merge
172
- <RED>|<RESET> *<MAGENTA>-<RESET><MAGENTA>-<RESET><CYAN>-<RESET><CYAN>.<RESET> octopus-merge
173
- <RED>|<RESET> <RED>|<RESET><BLUE>\<RESET> <MAGENTA>\<RESET> <CYAN>\<RESET>
174
- <RED>|<RESET><RED>/<RESET> <BLUE>/<RESET> <MAGENTA>/<RESET> <CYAN>/<RESET>
169
+ <RED>|<RESET> *<CYAN>-<RESET><CYAN>.<RESET> octopus-merge
170
+ <RED>|<RESET><RED>/<RESET><BLUE>|<RESET><MAGENTA>\<RESET> <CYAN>\<RESET>
171
<RED>|<RESET> <BLUE>|<RESET> <MAGENTA>|<RESET> * 4
172
<RED>|<RESET> <BLUE>|<RESET> * <CYAN>|<RESET> 3
173
<RED>|<RESET> <BLUE>|<RESET> <CYAN>|<RESET><CYAN>/<RESET>
t/t4215-log-skewed-merges.sh
+39
-6
@@ -11,12 +11,8 @@ test_expect_success 'log --graph with merge fusing with its left and right neigh
11
| * G
12
| |\
13
| | * F
14
- | | |
15
- | | \
16
- | *-. \ E
17
- | |\ \ \
18
- |/ / / /
19
- | | | /
14
+ | * \ E
15
+ |/|\ \
16
| | |/
17
| | * D
18
| * | C
@@ -40,4 +36,41 @@ test_expect_success 'log --graph with merge fusing with its left and right neigh
36
test_cmp expect actual
37
'
38
39
+test_expect_success 'log --graph with left-skewed merge' '
40
+ cat >expect <<-\EOF &&
41
+ *-----. 0_H
42
+ |\ \ \ \
43
+ | | | | * 0_G
44
+ | |_|_|/|
45
+ |/| | | |
46
+ | | | * \ 0_F
47
+ | |_|/|\ \
48
+ |/| | | |/
49
+ | | | | * 0_E
50
+ | |_|_|/
51
+ |/| | |
52
+ | | * | 0_D
53
+ | | |/
54
+ | | * 0_C
55
+ | |/
56
+ |/|
57
+ | * 0_B
58
+ |/
59
+ * 0_A
60
+ EOF
61
+
62
+ git checkout --orphan 0_p && test_commit 0_A &&
63
+ git checkout -b 0_q 0_p && test_commit 0_B &&
64
+ git checkout -b 0_r 0_p &&
65
+ test_commit 0_C &&
66
+ test_commit 0_D &&
67
+ git checkout -b 0_s 0_p && test_commit 0_E &&
68
+ git checkout -b 0_t 0_p && git merge --no-ff 0_r^ 0_s -m 0_F &&
69
+ git checkout 0_p && git merge --no-ff 0_s -m 0_G &&
70
+ git checkout @^ && git merge --no-ff 0_q 0_r 0_t 0_p -m 0_H &&
71
+
72
+ git log --graph --pretty=tformat:%s | sed "s/ *$//" >actual &&
73
+ test_cmp expect actual
74
+'
75
+
76
test_done