summaryrefslogtreecommitdiff
path: root/graph.c
diff options
context:
space:
mode:
Diffstat (limited to 'graph.c')
-rw-r--r--graph.c1336
1 files changed, 1336 insertions, 0 deletions
diff --git a/graph.c b/graph.c
new file mode 100644
index 0000000000..7358416a72
--- /dev/null
+++ b/graph.c
@@ -0,0 +1,1336 @@
+#include "cache.h"
+#include "commit.h"
+#include "color.h"
+#include "graph.h"
+#include "diff.h"
+#include "revision.h"
+
+/* Internal API */
+
+/*
+ * Output a padding line in the graph.
+ * This is similar to graph_next_line(). However, it is guaranteed to
+ * never print the current commit line. Instead, if the commit line is
+ * next, it will simply output a line of vertical padding, extending the
+ * branch lines downwards, but leaving them otherwise unchanged.
+ */
+static void graph_padding_line(struct git_graph *graph, struct strbuf *sb);
+
+/*
+ * Print a strbuf to stdout. If the graph is non-NULL, all lines but the
+ * first will be prefixed with the graph output.
+ *
+ * If the strbuf ends with a newline, the output will end after this
+ * 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 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().
+ */
+static void graph_show_strbuf(struct git_graph *graph, struct strbuf const *sb);
+
+/*
+ * TODO:
+ * - 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.
+ */
+
+struct column {
+ /*
+ * The parent commit of this column.
+ */
+ struct commit *commit;
+ /*
+ * The color to (optionally) print this column in. This is an
+ * index into column_colors.
+ */
+ unsigned short color;
+};
+
+enum graph_state {
+ GRAPH_PADDING,
+ GRAPH_SKIP,
+ GRAPH_PRE_COMMIT,
+ GRAPH_COMMIT,
+ GRAPH_POST_MERGE,
+ GRAPH_COLLAPSING
+};
+
+static const char **column_colors;
+static unsigned short column_colors_max;
+
+void graph_set_column_colors(const char **colors, unsigned short colors_max)
+{
+ column_colors = colors;
+ column_colors_max = colors_max;
+}
+
+static const char *column_get_color_code(unsigned short color)
+{
+ return column_colors[color];
+}
+
+static void strbuf_write_column(struct strbuf *sb, const struct column *c,
+ char col_char)
+{
+ if (c->color < column_colors_max)
+ strbuf_addstr(sb, column_get_color_code(c->color));
+ strbuf_addch(sb, col_char);
+ if (c->color < column_colors_max)
+ strbuf_addstr(sb, column_get_color_code(column_colors_max));
+}
+
+struct git_graph {
+ /*
+ * The commit currently being processed
+ */
+ struct commit *commit;
+ /* The rev-info used for the current traversal */
+ struct rev_info *revs;
+ /*
+ * 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;
+ /*
+ * The width of the graph output for this commit.
+ * All rows for this commit are padded to this width, so that
+ * messages printed after the graph output are aligned.
+ */
+ int width;
+ /*
+ * The next expansion row to print
+ * when state is GRAPH_PRE_COMMIT
+ */
+ int expansion_row;
+ /*
+ * The current output state.
+ * This tells us what kind of line graph_next_line() should output.
+ */
+ enum graph_state state;
+ /*
+ * The output state for the previous line of output.
+ * This is primarily used to determine how the first merge line
+ * should appear, based on the last line of the previous commit.
+ */
+ enum graph_state prev_state;
+ /*
+ * The index of the column that refers to this commit.
+ *
+ * If none of the incoming columns refer to this commit,
+ * this will be equal to num_columns.
+ */
+ int commit_index;
+ /*
+ * The commit_index for the previously displayed commit.
+ *
+ * This is used to determine how the first line of a merge
+ * graph output should appear, based on the last line of the
+ * previous commit.
+ */
+ int prev_commit_index;
+ /*
+ * The maximum number of columns that can be stored in the columns
+ * and new_columns arrays. This is also half the number of entries
+ * that can be stored in the mapping and new_mapping arrays.
+ */
+ int column_capacity;
+ /*
+ * The number of columns (also called "branch lines" in some places)
+ */
+ int num_columns;
+ /*
+ * The number of columns in the new_columns array
+ */
+ int num_new_columns;
+ /*
+ * The number of entries in the mapping array
+ */
+ int mapping_size;
+ /*
+ * The column state before we output the current commit.
+ */
+ struct column *columns;
+ /*
+ * The new column state after we output the current commit.
+ * Only valid when state is GRAPH_COLLAPSING.
+ */
+ struct column *new_columns;
+ /*
+ * An array that tracks the current state of each
+ * character in the output line during state GRAPH_COLLAPSING.
+ * Each entry is -1 if this character is empty, or a non-negative
+ * integer if the character contains a branch line. The value of
+ * the integer indicates the target position for this branch line.
+ * (I.e., this array maps the current column positions to their
+ * desired positions.)
+ *
+ * The maximum capacity of this array is always
+ * sizeof(int) * 2 * column_capacity.
+ */
+ int *mapping;
+ /*
+ * A temporary array for computing the next mapping state
+ * while we are outputting a mapping line. This is stored as part
+ * of the git_graph simply so we don't have to allocate a new
+ * temporary array each time we have to output a collapsing line.
+ */
+ int *new_mapping;
+ /*
+ * The current default column color being used. This is
+ * stored as an index into the array column_colors.
+ */
+ unsigned short default_column_color;
+};
+
+static struct strbuf *diff_output_prefix_callback(struct diff_options *opt, void *data)
+{
+ struct git_graph *graph = data;
+ static struct strbuf msgbuf = STRBUF_INIT;
+
+ assert(graph);
+
+ strbuf_reset(&msgbuf);
+ graph_padding_line(graph, &msgbuf);
+ return &msgbuf;
+}
+
+struct git_graph *graph_init(struct rev_info *opt)
+{
+ struct git_graph *graph = xmalloc(sizeof(struct git_graph));
+
+ if (!column_colors)
+ graph_set_column_colors(column_colors_ansi,
+ column_colors_ansi_max);
+
+ graph->commit = NULL;
+ graph->revs = opt;
+ graph->num_parents = 0;
+ graph->expansion_row = 0;
+ graph->state = GRAPH_PADDING;
+ graph->prev_state = GRAPH_PADDING;
+ graph->commit_index = 0;
+ graph->prev_commit_index = 0;
+ graph->num_columns = 0;
+ graph->num_new_columns = 0;
+ graph->mapping_size = 0;
+ /*
+ * Start the column color at the maximum value, since we'll
+ * always increment it for the first commit we output.
+ * This way we start at 0 for the first commit.
+ */
+ graph->default_column_color = column_colors_max - 1;
+
+ /*
+ * Allocate a reasonably large default number of columns
+ * We'll automatically grow columns later if we need more room.
+ */
+ graph->column_capacity = 30;
+ graph->columns = xmalloc(sizeof(struct column) *
+ graph->column_capacity);
+ graph->new_columns = xmalloc(sizeof(struct column) *
+ graph->column_capacity);
+ graph->mapping = xmalloc(sizeof(int) * 2 * graph->column_capacity);
+ graph->new_mapping = xmalloc(sizeof(int) * 2 * graph->column_capacity);
+
+ /*
+ * The diff output prefix callback, with this we can make
+ * all the diff output to align with the graph lines.
+ */
+ opt->diffopt.output_prefix = diff_output_prefix_callback;
+ opt->diffopt.output_prefix_data = graph;
+
+ return graph;
+}
+
+static void graph_update_state(struct git_graph *graph, enum graph_state s)
+{
+ graph->prev_state = graph->state;
+ graph->state = s;
+}
+
+static void graph_ensure_capacity(struct git_graph *graph, int num_columns)
+{
+ if (graph->column_capacity >= num_columns)
+ return;
+
+ do {
+ graph->column_capacity *= 2;
+ } while (graph->column_capacity < num_columns);
+
+ graph->columns = xrealloc(graph->columns,
+ sizeof(struct column) *
+ graph->column_capacity);
+ graph->new_columns = xrealloc(graph->new_columns,
+ sizeof(struct column) *
+ graph->column_capacity);
+ graph->mapping = xrealloc(graph->mapping,
+ sizeof(int) * 2 * graph->column_capacity);
+ graph->new_mapping = xrealloc(graph->new_mapping,
+ 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 git_graph *graph, struct commit *commit)
+{
+ /*
+ * If revs->boundary is set, commits whose children have
+ * been shown are always interesting, even if they have the
+ * UNINTERESTING or TREESAME flags set.
+ */
+ if (graph->revs && graph->revs->boundary) {
+ if (commit->object.flags & CHILD_SHOWN)
+ return 1;
+ }
+
+ /*
+ * Otherwise, use get_commit_action() to see if this commit is
+ * interesting
+ */
+ return get_commit_action(graph->revs, commit) == commit_show;
+}
+
+static struct commit_list *next_interesting_parent(struct git_graph *graph,
+ struct commit_list *orig)
+{
+ struct commit_list *list;
+
+ /*
+ * If revs->first_parent_only is set, only the first
+ * parent is interesting. None of the others are.
+ */
+ if (graph->revs->first_parent_only)
+ return NULL;
+
+ /*
+ * Return the next interesting commit after orig
+ */
+ for (list = orig->next; list; list = list->next) {
+ if (graph_is_interesting(graph, list->item))
+ return list;
+ }
+
+ return NULL;
+}
+
+static struct commit_list *first_interesting_parent(struct git_graph *graph)
+{
+ struct commit_list *parents = graph->commit->parents;
+
+ /*
+ * If this commit has no parents, ignore it
+ */
+ if (!parents)
+ return NULL;
+
+ /*
+ * If the first parent is interesting, return it
+ */
+ if (graph_is_interesting(graph, parents->item))
+ return parents;
+
+ /*
+ * Otherwise, call next_interesting_parent() to get
+ * the next interesting parent
+ */
+ return next_interesting_parent(graph, parents);
+}
+
+static unsigned short graph_get_current_column_color(const struct git_graph *graph)
+{
+ if (!want_color(graph->revs->diffopt.use_color))
+ return column_colors_max;
+ return graph->default_column_color;
+}
+
+/*
+ * Update the graph's default column color.
+ */
+static void graph_increment_column_color(struct git_graph *graph)
+{
+ graph->default_column_color = (graph->default_column_color + 1) %
+ column_colors_max;
+}
+
+static unsigned short graph_find_commit_color(const struct git_graph *graph,
+ const struct commit *commit)
+{
+ int i;
+ for (i = 0; i < graph->num_columns; i++) {
+ if (graph->columns[i].commit == commit)
+ return graph->columns[i].color;
+ }
+ return graph_get_current_column_color(graph);
+}
+
+static void graph_insert_into_new_columns(struct git_graph *graph,
+ struct commit *commit,
+ int *mapping_index)
+{
+ int i;
+
+ /*
+ * If the commit is already in the new_columns list, we don't need to
+ * add it. Just update the mapping correctly.
+ */
+ for (i = 0; i < graph->num_new_columns; i++) {
+ if (graph->new_columns[i].commit == commit) {
+ graph->mapping[*mapping_index] = i;
+ *mapping_index += 2;
+ return;
+ }
+ }
+
+ /*
+ * This commit isn't already in new_columns. Add it.
+ */
+ graph->new_columns[graph->num_new_columns].commit = commit;
+ graph->new_columns[graph->num_new_columns].color = graph_find_commit_color(graph, commit);
+ graph->mapping[*mapping_index] = graph->num_new_columns;
+ *mapping_index += 2;
+ graph->num_new_columns++;
+}
+
+static void graph_update_width(struct git_graph *graph,
+ int is_commit_in_existing_columns)
+{
+ /*
+ * Compute the width needed to display the graph for this commit.
+ * This is the maximum width needed for any row. All other rows
+ * will be padded to this width.
+ *
+ * Compute the number of columns in the widest row:
+ * Count each existing column (graph->num_columns), and each new
+ * column added by this commit.
+ */
+ int max_cols = graph->num_columns + graph->num_parents;
+
+ /*
+ * 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++;
+
+ /*
+ * We added a column for the current commit as part of
+ * graph->num_parents. If the current commit was already in
+ * graph->columns, then we have double counted it.
+ */
+ if (is_commit_in_existing_columns)
+ max_cols--;
+
+ /*
+ * Each column takes up 2 spaces
+ */
+ graph->width = max_cols * 2;
+}
+
+static void graph_update_columns(struct git_graph *graph)
+{
+ struct commit_list *parent;
+ struct column *tmp_columns;
+ int max_new_columns;
+ int mapping_idx;
+ int i, seen_this, is_commit_in_columns;
+
+ /*
+ * Swap graph->columns with graph->new_columns
+ * graph->columns contains the state for the previous commit,
+ * and new_columns now contains the state for our commit.
+ *
+ * We'll re-use the old columns array as storage to compute the new
+ * columns list for the commit after this one.
+ */
+ tmp_columns = graph->columns;
+ graph->columns = graph->new_columns;
+ graph->num_columns = graph->num_new_columns;
+
+ graph->new_columns = tmp_columns;
+ graph->num_new_columns = 0;
+
+ /*
+ * Now update new_columns and mapping with the information for the
+ * commit after this one.
+ *
+ * First, make sure we have enough room. At most, there will
+ * be graph->num_columns + graph->num_parents columns for the next
+ * commit.
+ */
+ max_new_columns = graph->num_columns + graph->num_parents;
+ graph_ensure_capacity(graph, max_new_columns);
+
+ /*
+ * Clear out graph->mapping
+ */
+ graph->mapping_size = 2 * max_new_columns;
+ for (i = 0; i < graph->mapping_size; i++)
+ graph->mapping[i] = -1;
+
+ /*
+ * Populate graph->new_columns and graph->mapping
+ *
+ * Some of the parents of this commit may already be in
+ * graph->columns. If so, graph->new_columns should only contain a
+ * single entry for each such commit. graph->mapping should
+ * contain information about where each current branch line is
+ * supposed to end up after the collapsing is performed.
+ */
+ seen_this = 0;
+ mapping_idx = 0;
+ is_commit_in_columns = 1;
+ for (i = 0; i <= graph->num_columns; i++) {
+ struct commit *col_commit;
+ if (i == graph->num_columns) {
+ if (seen_this)
+ break;
+ is_commit_in_columns = 0;
+ col_commit = graph->commit;
+ } else {
+ col_commit = graph->columns[i].commit;
+ }
+
+ if (col_commit == graph->commit) {
+ int old_mapping_idx = mapping_idx;
+ seen_this = 1;
+ graph->commit_index = i;
+ for (parent = first_interesting_parent(graph);
+ parent;
+ parent = next_interesting_parent(graph, parent)) {
+ /*
+ * If this is a merge, or the start of a new
+ * childless column, increment the current
+ * color.
+ */
+ if (graph->num_parents > 1 ||
+ !is_commit_in_columns) {
+ graph_increment_column_color(graph);
+ }
+ graph_insert_into_new_columns(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);
+ }
+ }
+
+ /*
+ * Shrink mapping_size to be the minimum necessary
+ */
+ while (graph->mapping_size > 1 &&
+ graph->mapping[graph->mapping_size - 1] < 0)
+ graph->mapping_size--;
+
+ /*
+ * Compute graph->width for this commit
+ */
+ graph_update_width(graph, is_commit_in_columns);
+}
+
+void graph_update(struct git_graph *graph, struct commit *commit)
+{
+ struct commit_list *parent;
+
+ /*
+ * Set the new commit
+ */
+ graph->commit = commit;
+
+ /*
+ * Count how many interesting parents this commit has
+ */
+ graph->num_parents = 0;
+ for (parent = first_interesting_parent(graph);
+ parent;
+ parent = next_interesting_parent(graph, parent))
+ {
+ graph->num_parents++;
+ }
+
+ /*
+ * Store the old commit_index in prev_commit_index.
+ * graph_update_columns() will update graph->commit_index for this
+ * commit.
+ */
+ graph->prev_commit_index = graph->commit_index;
+
+ /*
+ * Call graph_update_columns() to update
+ * columns, new_columns, and mapping.
+ */
+ graph_update_columns(graph);
+
+ graph->expansion_row = 0;
+
+ /*
+ * Update graph->state.
+ * Note that we don't call graph_update_state() here, since
+ * we don't want to update graph->prev_state. No line for
+ * graph->state was ever printed.
+ *
+ * If the previous commit didn't get to the GRAPH_PADDING state,
+ * it never finished its output. Goto GRAPH_SKIP, to print out
+ * a line to indicate that portion of the graph is missing.
+ *
+ * If there are 3 or more parents, we may need to print extra rows
+ * before the commit, to expand the branch lines around it and make
+ * room for it. We need to do this only if there is a branch row
+ * (or more) to the right of this commit.
+ *
+ * If there are less than 3 parents, we can immediately print the
+ * commit line.
+ */
+ if (graph->state != GRAPH_PADDING)
+ graph->state = GRAPH_SKIP;
+ else if (graph->num_parents >= 3 &&
+ graph->commit_index < (graph->num_columns - 1))
+ graph->state = GRAPH_PRE_COMMIT;
+ else
+ graph->state = GRAPH_COMMIT;
+}
+
+static int graph_is_mapping_correct(struct git_graph *graph)
+{
+ int i;
+
+ /*
+ * The mapping is up to date if each entry is at its target,
+ * or is 1 greater than its target.
+ * (If it is 1 greater than the target, '/' will be printed, so it
+ * will look correct on the next row.)
+ */
+ for (i = 0; i < graph->mapping_size; i++) {
+ int target = graph->mapping[i];
+ if (target < 0)
+ continue;
+ if (target == (i / 2))
+ continue;
+ return 0;
+ }
+
+ return 1;
+}
+
+static void graph_pad_horizontally(struct git_graph *graph, struct strbuf *sb,
+ int chars_written)
+{
+ /*
+ * Add additional spaces to the end of the strbuf, so that all
+ * lines for a particular commit have the same width.
+ *
+ * This way, fields printed to the right of the graph will remain
+ * aligned for the entire commit.
+ */
+ int extra;
+ if (chars_written >= graph->width)
+ return;
+
+ extra = graph->width - chars_written;
+ strbuf_addf(sb, "%*s", (int) extra, "");
+}
+
+static void graph_output_padding_line(struct git_graph *graph,
+ struct strbuf *sb)
+{
+ int i;
+
+ /*
+ * We could conceivable be called with a NULL commit
+ * if our caller has a bug, and invokes graph_next_line()
+ * immediately after graph_init(), without first calling
+ * graph_update(). Return without outputting anything in this
+ * case.
+ */
+ if (!graph->commit)
+ return;
+
+ /*
+ * Output a padding row, that leaves all branch lines unchanged
+ */
+ for (i = 0; i < graph->num_new_columns; i++) {
+ strbuf_write_column(sb, &graph->new_columns[i], '|');
+ strbuf_addch(sb, ' ');
+ }
+
+ graph_pad_horizontally(graph, sb, graph->num_new_columns * 2);
+}
+
+static void graph_output_skip_line(struct git_graph *graph, struct strbuf *sb)
+{
+ /*
+ * Output an ellipsis to indicate that a portion
+ * of the graph is missing.
+ */
+ strbuf_addstr(sb, "...");
+ graph_pad_horizontally(graph, sb, 3);
+
+ if (graph->num_parents >= 3 &&
+ graph->commit_index < (graph->num_columns - 1))
+ graph_update_state(graph, GRAPH_PRE_COMMIT);
+ else
+ graph_update_state(graph, GRAPH_COMMIT);
+}
+
+static void graph_output_pre_commit_line(struct git_graph *graph,
+ struct strbuf *sb)
+{
+ int num_expansion_rows;
+ int i, seen_this;
+ int chars_written;
+
+ /*
+ * This function formats a row that increases the space around a commit
+ * with multiple parents, to make room for it. It should only be
+ * called when there are 3 or more parents.
+ *
+ * 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);
+
+ /*
+ * Output the row
+ */
+ seen_this = 0;
+ chars_written = 0;
+ for (i = 0; i < graph->num_columns; i++) {
+ struct column *col = &graph->columns[i];
+ if (col->commit == graph->commit) {
+ seen_this = 1;
+ strbuf_write_column(sb, col, '|');
+ 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.
+ * If the previous commit was a merge commit and
+ * ended in the GRAPH_POST_MERGE state, all branch
+ * lines after graph->prev_commit_index were
+ * printed as "\" on the previous line. Continue
+ * to print them as "\" on this line. Otherwise,
+ * print the branch lines as "|".
+ */
+ if (graph->prev_state == GRAPH_POST_MERGE &&
+ graph->prev_commit_index < i)
+ strbuf_write_column(sb, col, '\\');
+ else
+ strbuf_write_column(sb, col, '|');
+ chars_written++;
+ } else if (seen_this && (graph->expansion_row > 0)) {
+ strbuf_write_column(sb, col, '\\');
+ chars_written++;
+ } else {
+ strbuf_write_column(sb, col, '|');
+ chars_written++;
+ }
+ strbuf_addch(sb, ' ');
+ chars_written++;
+ }
+
+ graph_pad_horizontally(graph, sb, chars_written);
+
+ /*
+ * Increment graph->expansion_row,
+ * and move to state GRAPH_COMMIT if necessary
+ */
+ graph->expansion_row++;
+ if (graph->expansion_row >= num_expansion_rows)
+ graph_update_state(graph, GRAPH_COMMIT);
+}
+
+static void graph_output_commit_char(struct git_graph *graph, struct strbuf *sb)
+{
+ /*
+ * For boundary commits, print 'o'
+ * (We should only see boundary commits when revs->boundary is set.)
+ */
+ if (graph->commit->object.flags & BOUNDARY) {
+ assert(graph->revs->boundary);
+ strbuf_addch(sb, 'o');
+ return;
+ }
+
+ /*
+ * get_revision_mark() handles all other cases without assert()
+ */
+ strbuf_addstr(sb, get_revision_mark(graph->revs, graph->commit));
+}
+
+/*
+ * Draw an octopus merge and return the number of characters written.
+ */
+static int graph_draw_octopus_merge(struct git_graph *graph,
+ struct strbuf *sb)
+{
+ /*
+ * Here dashless_commits represents the number of parents
+ * which don't need to have dashes (because their edges fit
+ * neatly under the commit).
+ */
+ const int dashless_commits = 2;
+ int col_num, i;
+ int num_dashes =
+ ((graph->num_parents - dashless_commits) * 2) - 1;
+ for (i = 0; i < num_dashes; i++) {
+ col_num = (i / 2) + dashless_commits;
+ strbuf_write_column(sb, &graph->new_columns[col_num], '-');
+ }
+ col_num = (i / 2) + dashless_commits;
+ strbuf_write_column(sb, &graph->new_columns[col_num], '.');
+ return num_dashes + 1;
+}
+
+static void graph_output_commit_line(struct git_graph *graph, struct strbuf *sb)
+{
+ int seen_this = 0;
+ int i, chars_written;
+
+ /*
+ * Output the row containing this commit
+ * Iterate up to and including graph->num_columns,
+ * since the current commit may not be in any of the existing
+ * columns. (This happens when the current commit doesn't have any
+ * children that we have already processed.)
+ */
+ seen_this = 0;
+ chars_written = 0;
+ for (i = 0; i <= graph->num_columns; i++) {
+ struct column *col = &graph->columns[i];
+ struct commit *col_commit;
+ if (i == graph->num_columns) {
+ if (seen_this)
+ break;
+ col_commit = graph->commit;
+ } else {
+ col_commit = graph->columns[i].commit;
+ }
+
+ if (col_commit == graph->commit) {
+ seen_this = 1;
+ graph_output_commit_char(graph, sb);
+ chars_written++;
+
+ if (graph->num_parents > 2)
+ chars_written += graph_draw_octopus_merge(graph,
+ sb);
+ } else if (seen_this && (graph->num_parents > 2)) {
+ strbuf_write_column(sb, col, '\\');
+ chars_written++;
+ } else if (seen_this && (graph->num_parents == 2)) {
+ /*
+ * This is a 2-way merge commit.
+ * There is no GRAPH_PRE_COMMIT stage for 2-way
+ * merges, so this is the first line of output
+ * for this commit. Check to see what the previous
+ * line of output was.
+ *
+ * If it was GRAPH_POST_MERGE, the branch line
+ * coming into this commit may have been '\',
+ * and not '|' or '/'. If so, output the branch
+ * line as '\' on this line, instead of '|'. This
+ * makes the output look nicer.
+ */
+ if (graph->prev_state == GRAPH_POST_MERGE &&
+ graph->prev_commit_index < i)
+ strbuf_write_column(sb, col, '\\');
+ else
+ strbuf_write_column(sb, col, '|');
+ chars_written++;
+ } else {
+ strbuf_write_column(sb, col, '|');
+ chars_written++;
+ }
+ strbuf_addch(sb, ' ');
+ chars_written++;
+ }
+
+ graph_pad_horizontally(graph, sb, chars_written);
+
+ /*
+ * Update graph->state
+ */
+ if (graph->num_parents > 1)
+ graph_update_state(graph, GRAPH_POST_MERGE);
+ else if (graph_is_mapping_correct(graph))
+ graph_update_state(graph, GRAPH_PADDING);
+ else
+ graph_update_state(graph, GRAPH_COLLAPSING);
+}
+
+static struct column *find_new_column_by_commit(struct git_graph *graph,
+ struct commit *commit)
+{
+ int i;
+ for (i = 0; i < graph->num_new_columns; i++) {
+ if (graph->new_columns[i].commit == commit)
+ return &graph->new_columns[i];
+ }
+ return NULL;
+}
+
+static void graph_output_post_merge_line(struct git_graph *graph, struct strbuf *sb)
+{
+ int seen_this = 0;
+ int i, j, chars_written;
+
+ /*
+ * Output the post-merge row
+ */
+ chars_written = 0;
+ for (i = 0; i <= graph->num_columns; i++) {
+ struct column *col = &graph->columns[i];
+ struct commit *col_commit;
+ if (i == graph->num_columns) {
+ if (seen_this)
+ break;
+ col_commit = graph->commit;
+ } else {
+ col_commit = col->commit;
+ }
+
+ if (col_commit == graph->commit) {
+ /*
+ * Since the current commit is a merge find
+ * the columns for the parent commits in
+ * new_columns and use those to format the
+ * edges.
+ */
+ struct commit_list *parents = NULL;
+ struct column *par_column;
+ seen_this = 1;
+ parents = first_interesting_parent(graph);
+ assert(parents);
+ par_column = find_new_column_by_commit(graph, parents->item);
+ assert(par_column);
+
+ strbuf_write_column(sb, par_column, '|');
+ chars_written++;
+ for (j = 0; j < graph->num_parents - 1; j++) {
+ parents = next_interesting_parent(graph, parents);
+ assert(parents);
+ par_column = find_new_column_by_commit(graph, parents->item);
+ assert(par_column);
+ strbuf_write_column(sb, par_column, '\\');
+ strbuf_addch(sb, ' ');
+ }
+ chars_written += j * 2;
+ } else if (seen_this) {
+ strbuf_write_column(sb, col, '\\');
+ strbuf_addch(sb, ' ');
+ chars_written += 2;
+ } else {
+ strbuf_write_column(sb, col, '|');
+ strbuf_addch(sb, ' ');
+ chars_written += 2;
+ }
+ }
+
+ graph_pad_horizontally(graph, sb, chars_written);
+
+ /*
+ * Update graph->state
+ */
+ if (graph_is_mapping_correct(graph))
+ graph_update_state(graph, GRAPH_PADDING);
+ else
+ graph_update_state(graph, GRAPH_COLLAPSING);
+}
+
+static void graph_output_collapsing_line(struct git_graph *graph, struct strbuf *sb)
+{
+ int i;
+ int *tmp_mapping;
+ short used_horizontal = 0;
+ int horizontal_edge = -1;
+ int horizontal_edge_target = -1;
+
+ /*
+ * Clear out the new_mapping array
+ */
+ for (i = 0; i < graph->mapping_size; i++)
+ graph->new_mapping[i] = -1;
+
+ for (i = 0; i < graph->mapping_size; i++) {
+ int target = graph->mapping[i];
+ if (target < 0)
+ continue;
+
+ /*
+ * Since update_columns() always inserts the leftmost
+ * column first, each branch's target location should
+ * always be either its current location or to the left of
+ * its current location.
+ *
+ * We never have to move branches to the right. This makes
+ * the graph much more legible, since whenever branches
+ * cross, only one is moving directions.
+ */
+ assert(target * 2 <= i);
+
+ if (target * 2 == i) {
+ /*
+ * This column is already in the
+ * correct place
+ */
+ assert(graph->new_mapping[i] == -1);
+ graph->new_mapping[i] = target;
+ } else if (graph->new_mapping[i - 1] < 0) {
+ /*
+ * Nothing is to the left.
+ * 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
+ * already, and it is our target. We
+ * combine with this line, since we share
+ * the same parent commit.
+ *
+ * We don't have to add anything to the
+ * output or new_mapping, since the
+ * existing branch line has already taken
+ * care of it.
+ */
+ } else {
+ /*
+ * There is a branch line to our left,
+ * but it isn't our target. We need to
+ * cross over it.
+ *
+ * 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;
+ }
+ }
+
+ /*
+ * The new mapping may be 1 smaller than the old mapping
+ */
+ if (graph->new_mapping[graph->mapping_size - 1] < 0)
+ graph->mapping_size--;
+
+ /*
+ * Output out a line based on the new mapping info
+ */
+ for (i = 0; i < graph->mapping_size; i++) {
+ int target = graph->new_mapping[i];
+ if (target < 0)
+ strbuf_addch(sb, ' ');
+ else if (target * 2 == i)
+ strbuf_write_column(sb, &graph->new_columns[target], '|');
+ 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);
+
+ /*
+ * Swap mapping and new_mapping
+ */
+ tmp_mapping = graph->mapping;
+ graph->mapping = graph->new_mapping;
+ graph->new_mapping = tmp_mapping;
+
+ /*
+ * If graph->mapping indicates that all of the branch lines
+ * are already in the correct positions, we are done.
+ * Otherwise, we need to collapse some branch lines together.
+ */
+ if (graph_is_mapping_correct(graph))
+ graph_update_state(graph, GRAPH_PADDING);
+}
+
+int graph_next_line(struct git_graph *graph, struct strbuf *sb)
+{
+ switch (graph->state) {
+ case GRAPH_PADDING:
+ graph_output_padding_line(graph, sb);
+ return 0;
+ case GRAPH_SKIP:
+ graph_output_skip_line(graph, sb);
+ return 0;
+ case GRAPH_PRE_COMMIT:
+ graph_output_pre_commit_line(graph, sb);
+ return 0;
+ case GRAPH_COMMIT:
+ graph_output_commit_line(graph, sb);
+ return 1;
+ case GRAPH_POST_MERGE:
+ graph_output_post_merge_line(graph, sb);
+ return 0;
+ case GRAPH_COLLAPSING:
+ graph_output_collapsing_line(graph, sb);
+ return 0;
+ }
+
+ assert(0);
+ return 0;
+}
+
+static void graph_padding_line(struct git_graph *graph, struct strbuf *sb)
+{
+ int i, j;
+
+ if (graph->state != GRAPH_COMMIT) {
+ graph_next_line(graph, sb);
+ return;
+ }
+
+ /*
+ * Output the row containing this commit
+ * Iterate up to and including graph->num_columns,
+ * since the current commit may not be in any of the existing
+ * columns. (This happens when the current commit doesn't have any
+ * children that we have already processed.)
+ */
+ for (i = 0; i < graph->num_columns; i++) {
+ struct column *col = &graph->columns[i];
+ struct commit *col_commit = col->commit;
+ if (col_commit == graph->commit) {
+ strbuf_write_column(sb, col, '|');
+
+ if (graph->num_parents < 3)
+ strbuf_addch(sb, ' ');
+ else {
+ int num_spaces = ((graph->num_parents - 2) * 2);
+ for (j = 0; j < num_spaces; j++)
+ strbuf_addch(sb, ' ');
+ }
+ } else {
+ strbuf_write_column(sb, col, '|');
+ strbuf_addch(sb, ' ');
+ }
+ }
+
+ graph_pad_horizontally(graph, sb, graph->num_columns);
+
+ /*
+ * Update graph->prev_state since we have output a padding line
+ */
+ graph->prev_state = GRAPH_PADDING;
+}
+
+int graph_is_commit_finished(struct git_graph const *graph)
+{
+ return (graph->state == GRAPH_PADDING);
+}
+
+void graph_show_commit(struct git_graph *graph)
+{
+ struct strbuf msgbuf = STRBUF_INIT;
+ int shown_commit_line = 0;
+
+ if (!graph)
+ return;
+
+ while (!shown_commit_line) {
+ shown_commit_line = graph_next_line(graph, &msgbuf);
+ fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
+ if (!shown_commit_line)
+ putchar('\n');
+ strbuf_setlen(&msgbuf, 0);
+ }
+
+ strbuf_release(&msgbuf);
+}
+
+void graph_show_oneline(struct git_graph *graph)
+{
+ struct strbuf msgbuf = STRBUF_INIT;
+
+ if (!graph)
+ return;
+
+ graph_next_line(graph, &msgbuf);
+ fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
+ strbuf_release(&msgbuf);
+}
+
+void graph_show_padding(struct git_graph *graph)
+{
+ struct strbuf msgbuf = STRBUF_INIT;
+
+ if (!graph)
+ return;
+
+ graph_padding_line(graph, &msgbuf);
+ fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
+ strbuf_release(&msgbuf);
+}
+
+int graph_show_remainder(struct git_graph *graph)
+{
+ struct strbuf msgbuf = STRBUF_INIT;
+ int shown = 0;
+
+ if (!graph)
+ return 0;
+
+ if (graph_is_commit_finished(graph))
+ return 0;
+
+ for (;;) {
+ graph_next_line(graph, &msgbuf);
+ fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
+ strbuf_setlen(&msgbuf, 0);
+ shown = 1;
+
+ if (!graph_is_commit_finished(graph))
+ putchar('\n');
+ else
+ break;
+ }
+ strbuf_release(&msgbuf);
+
+ return shown;
+}
+
+
+static void graph_show_strbuf(struct git_graph *graph, struct strbuf const *sb)
+{
+ char *p;
+
+ if (!graph) {
+ fwrite(sb->buf, sizeof(char), sb->len, stdout);
+ return;
+ }
+
+ /*
+ * Print the strbuf line by line,
+ * and display the graph info before each line but the first.
+ */
+ p = sb->buf;
+ while (p) {
+ size_t len;
+ char *next_p = strchr(p, '\n');
+ if (next_p) {
+ next_p++;
+ len = next_p - p;
+ } else {
+ len = (sb->buf + sb->len) - p;
+ }
+ fwrite(p, sizeof(char), len, stdout);
+ if (next_p && *next_p != '\0')
+ graph_show_oneline(graph);
+ p = next_p;
+ }
+}
+
+void graph_show_commit_msg(struct git_graph *graph,
+ struct strbuf const *sb)
+{
+ int newline_terminated;
+
+ if (!graph) {
+ /*
+ * If there's no graph, just print the message buffer.
+ *
+ * The message buffer for CMIT_FMT_ONELINE and
+ * CMIT_FMT_USERFORMAT are already missing a terminating
+ * newline. All of the other formats should have it.
+ */
+ fwrite(sb->buf, sizeof(char), sb->len, stdout);
+ return;
+ }
+
+ newline_terminated = (sb->len && sb->buf[sb->len - 1] == '\n');
+
+ /*
+ * Show the commit message
+ */
+ graph_show_strbuf(graph, sb);
+
+ /*
+ * If there is more output needed for this commit, show it now
+ */
+ if (!graph_is_commit_finished(graph)) {
+ /*
+ * If sb doesn't have a terminating newline, print one now,
+ * so we can start the remainder of the graph output on a
+ * new line.
+ */
+ if (!newline_terminated)
+ putchar('\n');
+
+ graph_show_remainder(graph);
+
+ /*
+ * If sb ends with a newline, our output should too.
+ */
+ if (newline_terminated)
+ putchar('\n');
+ }
+}