From d62893ecc125767d44a194279bcaffa0d02d2572 Mon Sep 17 00:00:00 2001 From: James Coglan Date: Tue, 15 Oct 2019 23:47:55 +0000 Subject: graph: commit and post-merge lines for left-skewed merges Following the introduction of "left-skewed" merges, which are merges whose first parent fuses with another edge to its left, we have some more edge cases to deal with in the display of commit and post-merge lines. The current graph code handles the following cases for edges appearing to the right of the commit (*) on commit lines. A 2-way merge is usually followed by vertical lines: | | | | * | | |\ \ An octopus merge (more than two parents) is always followed by edges sloping to the right: | | \ | | \ | *-. \ | *---. \ | |\ \ \ | |\ \ \ \ A 2-way merge is followed by a right-sloping edge if the commit line immediately follows a post-merge line for a commit that appears in the same column as the current commit, or any column to the left of that: | * | * | | |\ | |\ \ | * \ | | * \ | |\ \ | | |\ \ This commit introduces the following new cases for commit lines. If a 2-way merge skews to the left, then the edges to its right are always vertical lines, even if the commit follows a post-merge line: | | | | |\ | * | | * | |/| | |/| | A commit with 3 parents that skews left is followed by vertical edges: | | | | * | |/|\ \ If a 3-way left-skewed merge commit appears immediately after a post-merge line, then it may be followed the right-sloping edges, just like a 2-way merge that is not skewed. | |\ | * \ |/|\ \ Octopus merges with 4 or more parents that skew to the left will always be followed by right-sloping edges, because the existing columns need to expand around the merge. | | \ | *-. \ |/|\ \ \ On post-merge lines, usually all edges following the current commit slope to the right: | * | | | |\ \ \ However, if the commit is a left-skewed 2-way merge, the edges to its right remain vertical. We also need to display a space after the vertical line descending from the commit marker, whereas this line would normally be followed by a backslash. | * | | |/| | | If a left-skewed merge has more than 2 parents, then the edges to its right are still sloped as they bend around the edges introduced by the merge. | * | | |/|\ \ \ To handle these new cases, we need to know not just how many parents each commit has, but how many new columns it adds to the display; this quantity is recorded in the `edges_added` field for the current commit, and `prev_edges_added` field for the previous commit. Here, "column" refers to visual columns, not the logical columns of the `columns` array. This is because even if all the commit's parents end up fusing with existing edges, they initially introduce distinct edges in the commit and post-merge lines before those edges collapse. For example, a 3-way merge whose 2nd and 3rd parents fuse with existing edges still introduces 2 visual columns that affect the display of edges to their right. | | | \ | | *-. \ | | |\ \ \ | |_|/ / / |/| | / / | | |/ / | |/| | | | | | This merge does not introduce any *logical* columns; there are 4 edges before and after this commit once all edges have collapsed. But it does initially introduce 2 new edges that need to be accommodated by the edges to their right. Signed-off-by: James Coglan Signed-off-by: Junio C Hamano --- graph.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 58 insertions(+), 5 deletions(-) (limited to 'graph.c') diff --git a/graph.c b/graph.c index e37127f5ab..21edad8085 100644 --- a/graph.c +++ b/graph.c @@ -216,6 +216,46 @@ struct git_graph { * |/| | | | | | | | | | * */ int merge_layout; + /* + * The number of columns added to the graph by the current commit. For + * 2-way and octopus merges, this is is usually one less than the + * number of parents: + * + * | | | | | \ + * | * | | *---. \ + * | |\ \ | |\ \ \ \ + * | | | | | | | | | | + * + * num_parents: 2 num_parents: 4 + * edges_added: 1 edges_added: 3 + * + * For left-skewed merges, the first parent fuses with its neighbor and + * so one less column is added: + * + * | | | | | \ + * | * | | *-. \ + * |/| | |/|\ \ \ + * | | | | | | | | + * + * num_parents: 2 num_parents: 4 + * edges_added: 0 edges_added: 2 + * + * This number determines how edges to the right of the merge are + * displayed in commit and post-merge lines; if no columns have been + * added then a vertical line should be used where a right-tracking + * line would otherwise be used. + * + * | * \ | * | + * | |\ \ |/| | + * | | * \ | * | + */ + int edges_added; + /* + * The number of columns added by the previous commit, which is used to + * smooth edges appearing to the right of a commit in a commit line + * following a post-merge line. + */ + int prev_edges_added; /* * The maximum number of columns that can be stored in the columns * and new_columns arrays. This is also half the number of entries @@ -328,6 +368,8 @@ struct git_graph *graph_init(struct rev_info *opt) graph->commit_index = 0; graph->prev_commit_index = 0; graph->merge_layout = 0; + graph->edges_added = 0; + graph->prev_edges_added = 0; graph->num_columns = 0; graph->num_new_columns = 0; graph->mapping_size = 0; @@ -689,6 +731,9 @@ void graph_update(struct git_graph *graph, struct commit *commit) */ graph_update_columns(graph); + graph->prev_edges_added = graph->edges_added; + graph->edges_added = graph->num_parents + graph->merge_layout - 2; + graph->expansion_row = 0; /* @@ -947,12 +992,13 @@ static void graph_output_commit_line(struct git_graph *graph, struct graph_line if (graph->num_parents > 2) graph_draw_octopus_merge(graph, line); - } else if (seen_this && (graph->num_parents > 2)) { + } else if (seen_this && (graph->edges_added > 1)) { graph_line_write_column(line, col, '\\'); - } else if (seen_this && (graph->num_parents == 2)) { + } else if (seen_this && (graph->edges_added == 1)) { /* - * This is a 2-way merge commit. - * There is no GRAPH_PRE_COMMIT stage for 2-way + * This is either a right-skewed 2-way merge + * commit, or a left-skewed 3-way merge. + * There is no GRAPH_PRE_COMMIT stage for such * merges, so this is the first line of output * for this commit. Check to see what the previous * line of output was. @@ -964,6 +1010,7 @@ static void graph_output_commit_line(struct git_graph *graph, struct graph_line * makes the output look nicer. */ if (graph->prev_state == GRAPH_POST_MERGE && + graph->prev_edges_added > 0 && graph->prev_commit_index < i) graph_line_write_column(line, col, '\\'); else @@ -1033,8 +1080,14 @@ static void graph_output_post_merge_line(struct git_graph *graph, struct graph_l else idx++; } + if (graph->edges_added == 0) + graph_line_addch(line, ' '); + } else if (seen_this) { - graph_line_write_column(line, col, '\\'); + if (graph->edges_added > 0) + graph_line_write_column(line, col, '\\'); + else + graph_line_write_column(line, col, '|'); graph_line_addch(line, ' '); } else { graph_line_write_column(line, col, '|'); -- cgit v1.2.1