Fix typos / spelling in comments
[gitweb.git] / graph.c
diff --git a/graph.c b/graph.c
index 9d6ed30b0bef22bd8b56da9a12688c760b661776..06fbeb6c2416d0c1c5fd7df1a12924656592cdc3 100644 (file)
--- a/graph.c
+++ b/graph.c
@@ -1,15 +1,49 @@
 #include "cache.h"
 #include "commit.h"
+#include "color.h"
 #include "graph.h"
 #include "diff.h"
 #include "revision.h"
 
+/* Internal API */
+
 /*
- * TODO:
- * - Add colors to the graph.
- *   Pick a color for each column, and print all characters
- *   in that column with the specified color.
+ * Output the next line for a graph.
+ * This formats the next graph line into the specified strbuf.  It is not
+ * terminated with a newline.
+ *
+ * Returns 1 if the line includes the current commit, and 0 otherwise.
+ * graph_next_line() will return 1 exactly once for each time
+ * graph_update() is called.
+ */
+static int graph_next_line(struct git_graph *graph, struct strbuf *sb);
+
+/*
+ * 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.
@@ -35,9 +69,10 @@ struct column {
         */
        struct commit *commit;
        /*
-        * XXX: Once we add support for colors, struct column could also
-        * contain the color of its branch line.
+        * The color to (optionally) print this column in.  This is an
+        * index into column_colors.
         */
+       unsigned short color;
 };
 
 enum graph_state {
@@ -49,15 +84,54 @@ enum graph_state {
        GRAPH_COLLAPSING
 };
 
+/*
+ * The list of available column colors.
+ */
+static char column_colors[][COLOR_MAXLEN] = {
+       GIT_COLOR_RED,
+       GIT_COLOR_GREEN,
+       GIT_COLOR_YELLOW,
+       GIT_COLOR_BLUE,
+       GIT_COLOR_MAGENTA,
+       GIT_COLOR_CYAN,
+       GIT_COLOR_BOLD GIT_COLOR_RED,
+       GIT_COLOR_BOLD GIT_COLOR_GREEN,
+       GIT_COLOR_BOLD GIT_COLOR_YELLOW,
+       GIT_COLOR_BOLD GIT_COLOR_BLUE,
+       GIT_COLOR_BOLD GIT_COLOR_MAGENTA,
+       GIT_COLOR_BOLD GIT_COLOR_CYAN,
+};
+
+#define COLUMN_COLORS_MAX (ARRAY_SIZE(column_colors))
+
+static const char *column_get_color_code(const struct column *c)
+{
+       return column_colors[c->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));
+       strbuf_addch(sb, col_char);
+       if (c->color < COLUMN_COLORS_MAX)
+               strbuf_addstr(sb, GIT_COLOR_RESET);
+}
+
 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 parents this commit has.
-        * (Stored so we don't have to walk over them each time we need
-        * this number)
+        * 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;
        /*
@@ -76,6 +150,27 @@ struct git_graph {
         * 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
@@ -123,18 +218,28 @@ struct git_graph {
         * 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;
 };
 
-struct git_graph *graph_init(void)
+struct git_graph *graph_init(struct rev_info *opt)
 {
        struct git_graph *graph = xmalloc(sizeof(struct git_graph));
        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;
+       graph->default_column_color = 0;
 
        /*
         * Allocate a reasonably large default number of columns
@@ -151,12 +256,10 @@ struct git_graph *graph_init(void)
        return graph;
 }
 
-void graph_release(struct git_graph *graph)
+static void graph_update_state(struct git_graph *graph, enum graph_state s)
 {
-       free(graph->columns);
-       free(graph->new_columns);
-       free(graph->mapping);
-       free(graph);
+       graph->prev_state = graph->state;
+       graph->state = s;
 }
 
 static void graph_ensure_capacity(struct git_graph *graph, int num_columns)
@@ -180,18 +283,107 @@ static void graph_ensure_capacity(struct git_graph *graph, int num_columns)
                                      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;
+       }
+
+       /*
+        * Uninteresting and pruned commits won't be printed
+        */
+       return (commit->object.flags & (UNINTERESTING | TREESAME)) ? 0 : 1;
+}
+
+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 (!DIFF_OPT_TST(&graph->revs->diffopt, COLOR_DIFF))
+               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;
 
-       /*
-        * Ignore uinteresting and pruned commits
-        */
-       if (commit->object.flags & (UNINTERESTING | TREESAME))
-               return;
-
        /*
         * If the commit is already in the new_columns list, we don't need to
         * add it.  Just update the mapping correctly.
@@ -208,6 +400,7 @@ static void graph_insert_into_new_columns(struct git_graph *graph,
         * 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++;
@@ -228,8 +421,8 @@ static void graph_update_width(struct git_graph *graph,
        int max_cols = graph->num_columns + graph->num_parents;
 
        /*
-        * Even if the current commit has no parents, it still takes up a
-        * column for itself.
+        * 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++;
@@ -313,14 +506,30 @@ static void graph_update_columns(struct git_graph *graph)
                }
 
                if (col_commit == graph->commit) {
+                       int old_mapping_idx = mapping_idx;
                        seen_this = 1;
-                       for (parent = graph->commit->parents;
+                       graph->commit_index = i;
+                       for (parent = first_interesting_parent(graph);
                             parent;
-                            parent = parent->next) {
+                            parent = next_interesting_parent(graph, parent)) {
+                               /*
+                                * If this is a merge increment the current
+                                * color.
+                                */
+                               if (graph->num_parents > 1)
+                                       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);
@@ -350,11 +559,22 @@ void graph_update(struct git_graph *graph, struct commit *commit)
        graph->commit = commit;
 
        /*
-        * Count how many parents this commit has
+        * Count how many interesting parents this commit has
         */
        graph->num_parents = 0;
-       for (parent = commit->parents; parent; parent = parent->next)
+       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
@@ -366,21 +586,26 @@ void graph_update(struct git_graph *graph, struct commit *commit)
 
        /*
         * 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.
         *
-        * Otherwise, if there are 3 or more parents, we need to print
-        * extra rows before the commit, to expand the branch lines around
-        * it and make room for it.
+        * 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)
+       else if (graph->num_parents >= 3 &&
+                graph->commit_index < (graph->num_columns - 1))
                graph->state = GRAPH_PRE_COMMIT;
        else
                graph->state = GRAPH_COMMIT;
@@ -408,7 +633,8 @@ static int graph_is_mapping_correct(struct git_graph *graph)
        return 1;
 }
 
-static void graph_pad_horizontally(struct git_graph *graph, struct strbuf *sb)
+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
@@ -418,10 +644,10 @@ static void graph_pad_horizontally(struct git_graph *graph, struct strbuf *sb)
         * aligned for the entire commit.
         */
        int extra;
-       if (sb->len >= graph->width)
+       if (chars_written >= graph->width)
                return;
 
-       extra = graph->width - sb->len;
+       extra = graph->width - chars_written;
        strbuf_addf(sb, "%*s", (int) extra, "");
 }
 
@@ -444,10 +670,11 @@ static void graph_output_padding_line(struct git_graph *graph,
         * Output a padding row, that leaves all branch lines unchanged
         */
        for (i = 0; i < graph->num_new_columns; i++) {
-               strbuf_addstr(sb, "| ");
+               strbuf_write_column(sb, &graph->new_columns[i], '|');
+               strbuf_addch(sb, ' ');
        }
 
-       graph_pad_horizontally(graph, sb);
+       graph_pad_horizontally(graph, sb, graph->num_new_columns * 2);
 }
 
 static void graph_output_skip_line(struct git_graph *graph, struct strbuf *sb)
@@ -457,12 +684,13 @@ static void graph_output_skip_line(struct git_graph *graph, struct strbuf *sb)
         * of the graph is missing.
         */
        strbuf_addstr(sb, "...");
-       graph_pad_horizontally(graph, sb);
+       graph_pad_horizontally(graph, sb, 3);
 
-       if (graph->num_parents >= 3)
-               graph->state = GRAPH_PRE_COMMIT;
+       if (graph->num_parents >= 3 &&
+           graph->commit_index < (graph->num_columns - 1))
+               graph_update_state(graph, GRAPH_PRE_COMMIT);
        else
-               graph->state = GRAPH_COMMIT;
+               graph_update_state(graph, GRAPH_COMMIT);
 }
 
 static void graph_output_pre_commit_line(struct git_graph *graph,
@@ -470,6 +698,7 @@ static void graph_output_pre_commit_line(struct git_graph *graph,
 {
        int num_expansion_rows;
        int i, seen_this;
+       int chars_written;
 
        /*
         * This function formats a row that increases the space around a commit
@@ -492,19 +721,42 @@ static void graph_output_pre_commit_line(struct git_graph *graph,
         * 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_addf(sb, "| %*s", graph->expansion_row, "");
-               } else if (seen_this) {
-                       strbuf_addstr(sb, "\\ ");
+                       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_addstr(sb, "| ");
+                       strbuf_write_column(sb, col, '|');
+                       chars_written++;
                }
+               strbuf_addch(sb, ' ');
+               chars_written++;
        }
 
-       graph_pad_horizontally(graph, sb);
+       graph_pad_horizontally(graph, sb, chars_written);
 
        /*
         * Increment graph->expansion_row,
@@ -512,13 +764,68 @@ static void graph_output_pre_commit_line(struct git_graph *graph,
         */
        graph->expansion_row++;
        if (graph->expansion_row >= num_expansion_rows)
-               graph->state = GRAPH_COMMIT;
+               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;
+       }
+
+       /*
+        * If revs->left_right is set, print '<' for commits that
+        * come from the left side, and '>' for commits from the right
+        * side.
+        */
+       if (graph->revs && graph->revs->left_right) {
+               if (graph->commit->object.flags & SYMMETRIC_LEFT)
+                       strbuf_addch(sb, '<');
+               else
+                       strbuf_addch(sb, '>');
+               return;
+       }
+
+       /*
+        * Print '*' in all other cases
+        */
+       strbuf_addch(sb, '*');
+}
+
+/*
+ * 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;
 }
 
-void graph_output_commit_line(struct git_graph *graph, struct strbuf *sb)
+static void graph_output_commit_line(struct git_graph *graph, struct strbuf *sb)
 {
        int seen_this = 0;
-       int i, j;
+       int i, chars_written;
 
        /*
         * Output the row containing this commit
@@ -528,7 +835,9 @@ void graph_output_commit_line(struct git_graph *graph, struct strbuf *sb)
         * 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)
@@ -540,86 +849,136 @@ void graph_output_commit_line(struct git_graph *graph, struct strbuf *sb)
 
                if (col_commit == graph->commit) {
                        seen_this = 1;
-                       if (graph->num_parents > 1)
-                               strbuf_addch(sb, 'M');
-                       else
-                               strbuf_addch(sb, '*');
+                       graph_output_commit_char(graph, sb);
+                       chars_written++;
 
-                       if (graph->num_parents < 2)
-                               strbuf_addch(sb, ' ');
-                       else if (graph->num_parents == 2)
-                               strbuf_addstr(sb, "  ");
-                       else {
-                               int num_dashes =
-                                       ((graph->num_parents - 2) * 2) - 1;
-                               for (j = 0; j < num_dashes; j++)
-                                       strbuf_addch(sb, '-');
-                               strbuf_addstr(sb, ". ");
-                       }
-               } else if (seen_this && (graph->num_parents > 1)) {
-                       strbuf_addstr(sb, "\\ ");
+                       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_addstr(sb, "| ");
+                       strbuf_write_column(sb, col, '|');
+                       chars_written++;
                }
+               strbuf_addch(sb, ' ');
+               chars_written++;
        }
 
-       graph_pad_horizontally(graph, sb);
+       graph_pad_horizontally(graph, sb, chars_written);
 
        /*
         * Update graph->state
         */
        if (graph->num_parents > 1)
-               graph->state = GRAPH_POST_MERGE;
+               graph_update_state(graph, GRAPH_POST_MERGE);
        else if (graph_is_mapping_correct(graph))
-               graph->state = GRAPH_PADDING;
+               graph_update_state(graph, GRAPH_PADDING);
        else
-               graph->state = GRAPH_COLLAPSING;
+               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 0;
 }
 
-void graph_output_post_merge_line(struct git_graph *graph, struct strbuf *sb)
+static void graph_output_post_merge_line(struct git_graph *graph, struct strbuf *sb)
 {
        int seen_this = 0;
-       int i, j;
+       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 = graph->columns[i].commit;
+                       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;
-                       strbuf_addch(sb, '|');
-                       for (j = 0; j < graph->num_parents - 1; j++)
-                               strbuf_addstr(sb, "\\ ");
-                       if (graph->num_parents == 2)
+                       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, ' ');
-               } else if (seen_this && (graph->num_parents > 2)) {
-                       strbuf_addstr(sb, "\\ ");
+                       }
+                       chars_written += j * 2;
+               } else if (seen_this) {
+                       strbuf_write_column(sb, col, '\\');
+                       strbuf_addch(sb, ' ');
+                       chars_written += 2;
                } else {
-                       strbuf_addstr(sb, "| ");
+                       strbuf_write_column(sb, col, '|');
+                       strbuf_addch(sb, ' ');
+                       chars_written += 2;
                }
        }
 
-       graph_pad_horizontally(graph, sb);
+       graph_pad_horizontally(graph, sb, chars_written);
 
        /*
         * Update graph->state
         */
        if (graph_is_mapping_correct(graph))
-               graph->state = GRAPH_PADDING;
+               graph_update_state(graph, GRAPH_PADDING);
        else
-               graph->state = GRAPH_COLLAPSING;
+               graph_update_state(graph, GRAPH_COLLAPSING);
 }
 
-void graph_output_collapsing_line(struct git_graph *graph, struct strbuf *sb)
+static void graph_output_collapsing_line(struct git_graph *graph, struct strbuf *sb)
 {
        int i;
        int *tmp_mapping;
@@ -701,12 +1060,12 @@ void graph_output_collapsing_line(struct git_graph *graph, struct strbuf *sb)
                if (target < 0)
                        strbuf_addch(sb, ' ');
                else if (target * 2 == i)
-                       strbuf_addch(sb, '|');
+                       strbuf_write_column(sb, &graph->new_columns[target], '|');
                else
-                       strbuf_addch(sb, '/');
+                       strbuf_write_column(sb, &graph->new_columns[target], '/');
        }
 
-       graph_pad_horizontally(graph, sb);
+       graph_pad_horizontally(graph, sb, graph->mapping_size);
 
        /*
         * Swap mapping and new_mapping
@@ -721,10 +1080,10 @@ void graph_output_collapsing_line(struct git_graph *graph, struct strbuf *sb)
         * Otherwise, we need to collapse some branch lines together.
         */
        if (graph_is_mapping_correct(graph))
-               graph->state = GRAPH_PADDING;
+               graph_update_state(graph, GRAPH_PADDING);
 }
 
-int graph_next_line(struct git_graph *graph, struct strbuf *sb)
+static int graph_next_line(struct git_graph *graph, struct strbuf *sb)
 {
        switch (graph->state) {
        case GRAPH_PADDING:
@@ -751,7 +1110,7 @@ int graph_next_line(struct git_graph *graph, struct strbuf *sb)
        return 0;
 }
 
-void graph_padding_line(struct git_graph *graph, struct strbuf *sb)
+static void graph_padding_line(struct git_graph *graph, struct strbuf *sb)
 {
        int i, j;
 
@@ -768,9 +1127,10 @@ void graph_padding_line(struct git_graph *graph, struct strbuf *sb)
         * children that we have already processed.)
         */
        for (i = 0; i < graph->num_columns; i++) {
-               struct commit *col_commit = graph->columns[i].commit;
+               struct column *col = &graph->columns[i];
+               struct commit *col_commit = col->commit;
                if (col_commit == graph->commit) {
-                       strbuf_addch(sb, '|');
+                       strbuf_write_column(sb, col, '|');
 
                        if (graph->num_parents < 3)
                                strbuf_addch(sb, ' ');
@@ -780,11 +1140,17 @@ void graph_padding_line(struct git_graph *graph, struct strbuf *sb)
                                        strbuf_addch(sb, ' ');
                        }
                } else {
-                       strbuf_addstr(sb, "| ");
+                       strbuf_write_column(sb, col, '|');
+                       strbuf_addch(sb, ' ');
                }
        }
 
-       graph_pad_horizontally(graph, 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)
@@ -794,14 +1160,12 @@ int graph_is_commit_finished(struct git_graph const *graph)
 
 void graph_show_commit(struct git_graph *graph)
 {
-       struct strbuf msgbuf;
+       struct strbuf msgbuf = STRBUF_INIT;
        int shown_commit_line = 0;
 
        if (!graph)
                return;
 
-       strbuf_init(&msgbuf, 0);
-
        while (!shown_commit_line) {
                shown_commit_line = graph_next_line(graph, &msgbuf);
                fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
@@ -815,12 +1179,11 @@ void graph_show_commit(struct git_graph *graph)
 
 void graph_show_oneline(struct git_graph *graph)
 {
-       struct strbuf msgbuf;
+       struct strbuf msgbuf = STRBUF_INIT;
 
        if (!graph)
                return;
 
-       strbuf_init(&msgbuf, 0);
        graph_next_line(graph, &msgbuf);
        fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
        strbuf_release(&msgbuf);
@@ -828,12 +1191,11 @@ void graph_show_oneline(struct git_graph *graph)
 
 void graph_show_padding(struct git_graph *graph)
 {
-       struct strbuf msgbuf;
+       struct strbuf msgbuf = STRBUF_INIT;
 
        if (!graph)
                return;
 
-       strbuf_init(&msgbuf, 0);
        graph_padding_line(graph, &msgbuf);
        fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
        strbuf_release(&msgbuf);
@@ -841,7 +1203,7 @@ void graph_show_padding(struct git_graph *graph)
 
 int graph_show_remainder(struct git_graph *graph)
 {
-       struct strbuf msgbuf;
+       struct strbuf msgbuf = STRBUF_INIT;
        int shown = 0;
 
        if (!graph)
@@ -850,7 +1212,6 @@ int graph_show_remainder(struct git_graph *graph)
        if (graph_is_commit_finished(graph))
                return 0;
 
-       strbuf_init(&msgbuf, 0);
        for (;;) {
                graph_next_line(graph, &msgbuf);
                fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
@@ -868,7 +1229,7 @@ int graph_show_remainder(struct git_graph *graph)
 }
 
 
-void graph_show_strbuf(struct git_graph *graph, struct strbuf const *sb)
+static void graph_show_strbuf(struct git_graph *graph, struct strbuf const *sb)
 {
        char *p;