graph.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "color.h"
   4 #include "graph.h"
   5 #include "diff.h"
   6 #include "revision.h"
   7
   8 /* Internal API */
   9
  10 /*
  11  * Output the next line for a graph.
  12  * This formats the next graph line into the specified strbuf.  It is not
  13  * terminated with a newline.
  14  *
  15  * Returns 1 if the line includes the current commit, and 0 otherwise.
  16  * graph_next_line() will return 1 exactly once for each time
  17  * graph_update() is called.
  18  */
  19 static int graph_next_line(struct git_graph *graph, struct strbuf *sb);
  20
  21 /*
  22  * Set up a custom scheme for column colors.
  23  *
  24  * The default column color scheme inserts ANSI color escapes to colorize
  25  * the graph. The various color escapes are stored in an array of strings
  26  * where each entry corresponds to a color, except for the last entry,
  27  * which denotes the escape for resetting the color back to the default.
  28  * When generating the graph, strings from this array are inserted before
  29  * and after the various column characters.
  30  *
  31  * This function allows you to enable a custom array of color escapes.
  32  * The 'colors_max' argument is the index of the last "reset" entry.
  33  *
  34  * This functions must be called BEFORE graph_init() is called.
  35  */
  36 static void graph_set_column_colors(const char **colors, unsigned short colors_max);
  37
  38 /*
  39  * Output a padding line in the graph.
  40  * This is similar to graph_next_line().  However, it is guaranteed to
  41  * never print the current commit line.  Instead, if the commit line is
  42  * next, it will simply output a line of vertical padding, extending the
  43  * branch lines downwards, but leaving them otherwise unchanged.
  44  */
  45 static void graph_padding_line(struct git_graph *graph, struct strbuf *sb);
  46
  47 /*
  48  * Print a strbuf to stdout.  If the graph is non-NULL, all lines but the
  49  * first will be prefixed with the graph output.
  50  *
  51  * If the strbuf ends with a newline, the output will end after this
  52  * newline.  A new graph line will not be printed after the final newline.
  53  * If the strbuf is empty, no output will be printed.
  54  *
  55  * Since the first line will not include the graph output, the caller is
  56  * responsible for printing this line's graph (perhaps via
  57  * graph_show_commit() or graph_show_oneline()) before calling
  58  * graph_show_strbuf().
  59  */
  60 static void graph_show_strbuf(struct git_graph *graph, struct strbuf const *sb);
  61
  62 /*
  63  * TODO:
  64  * - Limit the number of columns, similar to the way gitk does.
  65  *   If we reach more than a specified number of columns, omit
  66  *   sections of some columns.
  67  */
  68
  69 struct column {
  70         /*
  71          * The parent commit of this column.
  72          */
  73         struct commit *commit;
  74         /*
  75          * The color to (optionally) print this column in.  This is an
  76          * index into column_colors.
  77          */
  78         unsigned short color;
  79 };
  80
  81 enum graph_state {
  82         GRAPH_PADDING,
  83         GRAPH_SKIP,
  84         GRAPH_PRE_COMMIT,
  85         GRAPH_COMMIT,
  86         GRAPH_POST_MERGE,
  87         GRAPH_COLLAPSING
  88 };
  89
  90 static const char **column_colors;
  91 static unsigned short column_colors_max;
  92
  93 static void graph_set_column_colors(const char **colors, unsigned short colors_max)
  94 {
  95         column_colors = colors;
  96         column_colors_max = colors_max;
  97 }
  98
  99 static const char *column_get_color_code(unsigned short color)
 100 {
 101         return column_colors[color];
 102 }
 103
 104 static void strbuf_write_column(struct strbuf *sb, const struct column *c,
 105                                 char col_char)
 106 {
 107         if (c->color < column_colors_max)
 108                 strbuf_addstr(sb, column_get_color_code(c->color));
 109         strbuf_addch(sb, col_char);
 110         if (c->color < column_colors_max)
 111                 strbuf_addstr(sb, column_get_color_code(column_colors_max));
 112 }
 113
 114 struct git_graph {
 115         /*
 116          * The commit currently being processed
 117          */
 118         struct commit *commit;
 119         /* The rev-info used for the current traversal */
 120         struct rev_info *revs;
 121         /*
 122          * The number of interesting parents that this commit has.
 123          *
 124          * Note that this is not the same as the actual number of parents.
 125          * This count excludes parents that won't be printed in the graph
 126          * output, as determined by graph_is_interesting().
 127          */
 128         int num_parents;
 129         /*
 130          * The width of the graph output for this commit.
 131          * All rows for this commit are padded to this width, so that
 132          * messages printed after the graph output are aligned.
 133          */
 134         int width;
 135         /*
 136          * The next expansion row to print
 137          * when state is GRAPH_PRE_COMMIT
 138          */
 139         int expansion_row;
 140         /*
 141          * The current output state.
 142          * This tells us what kind of line graph_next_line() should output.
 143          */
 144         enum graph_state state;
 145         /*
 146          * The output state for the previous line of output.
 147          * This is primarily used to determine how the first merge line
 148          * should appear, based on the last line of the previous commit.
 149          */
 150         enum graph_state prev_state;
 151         /*
 152          * The index of the column that refers to this commit.
 153          *
 154          * If none of the incoming columns refer to this commit,
 155          * this will be equal to num_columns.
 156          */
 157         int commit_index;
 158         /*
 159          * The commit_index for the previously displayed commit.
 160          *
 161          * This is used to determine how the first line of a merge
 162          * graph output should appear, based on the last line of the
 163          * previous commit.
 164          */
 165         int prev_commit_index;
 166         /*
 167          * The maximum number of columns that can be stored in the columns
 168          * and new_columns arrays.  This is also half the number of entries
 169          * that can be stored in the mapping and new_mapping arrays.
 170          */
 171         int column_capacity;
 172         /*
 173          * The number of columns (also called "branch lines" in some places)
 174          */
 175         int num_columns;
 176         /*
 177          * The number of columns in the new_columns array
 178          */
 179         int num_new_columns;
 180         /*
 181          * The number of entries in the mapping array
 182          */
 183         int mapping_size;
 184         /*
 185          * The column state before we output the current commit.
 186          */
 187         struct column *columns;
 188         /*
 189          * The new column state after we output the current commit.
 190          * Only valid when state is GRAPH_COLLAPSING.
 191          */
 192         struct column *new_columns;
 193         /*
 194          * An array that tracks the current state of each
 195          * character in the output line during state GRAPH_COLLAPSING.
 196          * Each entry is -1 if this character is empty, or a non-negative
 197          * integer if the character contains a branch line.  The value of
 198          * the integer indicates the target position for this branch line.
 199          * (I.e., this array maps the current column positions to their
 200          * desired positions.)
 201          *
 202          * The maximum capacity of this array is always
 203          * sizeof(int) * 2 * column_capacity.
 204          */
 205         int *mapping;
 206         /*
 207          * A temporary array for computing the next mapping state
 208          * while we are outputting a mapping line.  This is stored as part
 209          * of the git_graph simply so we don't have to allocate a new
 210          * temporary array each time we have to output a collapsing line.
 211          */
 212         int *new_mapping;
 213         /*
 214          * The current default column color being used.  This is
 215          * stored as an index into the array column_colors.
 216          */
 217         unsigned short default_column_color;
 218 };
 219
 220 static struct strbuf *diff_output_prefix_callback(struct diff_options *opt, void *data)
 221 {
 222         struct git_graph *graph = data;
 223         static struct strbuf msgbuf = STRBUF_INIT;
 224
 225         assert(opt);
 226         assert(graph);
 227
 228         opt->output_prefix_length = graph->width;
 229         strbuf_reset(&msgbuf);
 230         graph_padding_line(graph, &msgbuf);
 231         return &msgbuf;
 232 }
 233
 234 struct git_graph *graph_init(struct rev_info *opt)
 235 {
 236         struct git_graph *graph = xmalloc(sizeof(struct git_graph));
 237
 238         if (!column_colors)
 239                 graph_set_column_colors(column_colors_ansi,
 240                                         column_colors_ansi_max);
 241
 242         graph->commit = NULL;
 243         graph->revs = opt;
 244         graph->num_parents = 0;
 245         graph->expansion_row = 0;
 246         graph->state = GRAPH_PADDING;
 247         graph->prev_state = GRAPH_PADDING;
 248         graph->commit_index = 0;
 249         graph->prev_commit_index = 0;
 250         graph->num_columns = 0;
 251         graph->num_new_columns = 0;
 252         graph->mapping_size = 0;
 253         /*
 254          * Start the column color at the maximum value, since we'll
 255          * always increment it for the first commit we output.
 256          * This way we start at 0 for the first commit.
 257          */
 258         graph->default_column_color = column_colors_max - 1;
 259
 260         /*
 261          * Allocate a reasonably large default number of columns
 262          * We'll automatically grow columns later if we need more room.
 263          */
 264         graph->column_capacity = 30;
 265         graph->columns = xmalloc(sizeof(struct column) *
 266                                  graph->column_capacity);
 267         graph->new_columns = xmalloc(sizeof(struct column) *
 268                                      graph->column_capacity);
 269         graph->mapping = xmalloc(sizeof(int) * 2 * graph->column_capacity);
 270         graph->new_mapping = xmalloc(sizeof(int) * 2 * graph->column_capacity);
 271
 272         /*
 273          * The diff output prefix callback, with this we can make
 274          * all the diff output to align with the graph lines.
 275          */
 276         opt->diffopt.output_prefix = diff_output_prefix_callback;
 277         opt->diffopt.output_prefix_data = graph;
 278         opt->diffopt.output_prefix_length = 0;
 279
 280         return graph;
 281 }
 282
 283 static void graph_update_state(struct git_graph *graph, enum graph_state s)
 284 {
 285         graph->prev_state = graph->state;
 286         graph->state = s;
 287 }
 288
 289 static void graph_ensure_capacity(struct git_graph *graph, int num_columns)
 290 {
 291         if (graph->column_capacity >= num_columns)
 292                 return;
 293
 294         do {
 295                 graph->column_capacity *= 2;
 296         } while (graph->column_capacity < num_columns);
 297
 298         graph->columns = xrealloc(graph->columns,
 299                                   sizeof(struct column) *
 300                                   graph->column_capacity);
 301         graph->new_columns = xrealloc(graph->new_columns,
 302                                       sizeof(struct column) *
 303                                       graph->column_capacity);
 304         graph->mapping = xrealloc(graph->mapping,
 305                                   sizeof(int) * 2 * graph->column_capacity);
 306         graph->new_mapping = xrealloc(graph->new_mapping,
 307                                       sizeof(int) * 2 * graph->column_capacity);
 308 }
 309
 310 /*
 311  * Returns 1 if the commit will be printed in the graph output,
 312  * and 0 otherwise.
 313  */
 314 static int graph_is_interesting(struct git_graph *graph, struct commit *commit)
 315 {
 316         /*
 317          * If revs->boundary is set, commits whose children have
 318          * been shown are always interesting, even if they have the
 319          * UNINTERESTING or TREESAME flags set.
 320          */
 321         if (graph->revs && graph->revs->boundary) {
 322                 if (commit->object.flags & CHILD_SHOWN)
 323                         return 1;
 324         }
 325
 326         /*
 327          * Otherwise, use get_commit_action() to see if this commit is
 328          * interesting
 329          */
 330         return get_commit_action(graph->revs, commit) == commit_show;
 331 }
 332
 333 static struct commit_list *next_interesting_parent(struct git_graph *graph,
 334                                                    struct commit_list *orig)
 335 {
 336         struct commit_list *list;
 337
 338         /*
 339          * If revs->first_parent_only is set, only the first
 340          * parent is interesting.  None of the others are.
 341          */
 342         if (graph->revs->first_parent_only)
 343                 return NULL;
 344
 345         /*
 346          * Return the next interesting commit after orig
 347          */
 348         for (list = orig->next; list; list = list->next) {
 349                 if (graph_is_interesting(graph, list->item))
 350                         return list;
 351         }
 352
 353         return NULL;
 354 }
 355
 356 static struct commit_list *first_interesting_parent(struct git_graph *graph)
 357 {
 358         struct commit_list *parents = graph->commit->parents;
 359
 360         /*
 361          * If this commit has no parents, ignore it
 362          */
 363         if (!parents)
 364                 return NULL;
 365
 366         /*
 367          * If the first parent is interesting, return it
 368          */
 369         if (graph_is_interesting(graph, parents->item))
 370                 return parents;
 371
 372         /*
 373          * Otherwise, call next_interesting_parent() to get
 374          * the next interesting parent
 375          */
 376         return next_interesting_parent(graph, parents);
 377 }
 378
 379 static unsigned short graph_get_current_column_color(const struct git_graph *graph)
 380 {
 381         if (!want_color(graph->revs->diffopt.use_color))
 382                 return column_colors_max;
 383         return graph->default_column_color;
 384 }
 385
 386 /*
 387  * Update the graph's default column color.
 388  */
 389 static void graph_increment_column_color(struct git_graph *graph)
 390 {
 391         graph->default_column_color = (graph->default_column_color + 1) %
 392                 column_colors_max;
 393 }
 394
 395 static unsigned short graph_find_commit_color(const struct git_graph *graph,
 396                                               const struct commit *commit)
 397 {
 398         int i;
 399         for (i = 0; i < graph->num_columns; i++) {
 400                 if (graph->columns[i].commit == commit)
 401                         return graph->columns[i].color;
 402         }
 403         return graph_get_current_column_color(graph);
 404 }
 405
 406 static void graph_insert_into_new_columns(struct git_graph *graph,
 407                                           struct commit *commit,
 408                                           int *mapping_index)
 409 {
 410         int i;
 411
 412         /*
 413          * If the commit is already in the new_columns list, we don't need to
 414          * add it.  Just update the mapping correctly.
 415          */
 416         for (i = 0; i < graph->num_new_columns; i++) {
 417                 if (graph->new_columns[i].commit == commit) {
 418                         graph->mapping[*mapping_index] = i;
 419                         *mapping_index += 2;
 420                         return;
 421                 }
 422         }
 423
 424         /*
 425          * This commit isn't already in new_columns.  Add it.
 426          */
 427         graph->new_columns[graph->num_new_columns].commit = commit;
 428         graph->new_columns[graph->num_new_columns].color = graph_find_commit_color(graph, commit);
 429         graph->mapping[*mapping_index] = graph->num_new_columns;
 430         *mapping_index += 2;
 431         graph->num_new_columns++;
 432 }
 433
 434 static void graph_update_width(struct git_graph *graph,
 435                                int is_commit_in_existing_columns)
 436 {
 437         /*
 438          * Compute the width needed to display the graph for this commit.
 439          * This is the maximum width needed for any row.  All other rows
 440          * will be padded to this width.
 441          *
 442          * Compute the number of columns in the widest row:
 443          * Count each existing column (graph->num_columns), and each new
 444          * column added by this commit.
 445          */
 446         int max_cols = graph->num_columns + graph->num_parents;
 447
 448         /*
 449          * Even if the current commit has no parents to be printed, it
 450          * still takes up a column for itself.
 451          */
 452         if (graph->num_parents < 1)
 453                 max_cols++;
 454
 455         /*
 456          * We added a column for the current commit as part of
 457          * graph->num_parents.  If the current commit was already in
 458          * graph->columns, then we have double counted it.
 459          */
 460         if (is_commit_in_existing_columns)
 461                 max_cols--;
 462
 463         /*
 464          * Each column takes up 2 spaces
 465          */
 466         graph->width = max_cols * 2;
 467 }
 468
 469 static void graph_update_columns(struct git_graph *graph)
 470 {
 471         struct commit_list *parent;
 472         struct column *tmp_columns;
 473         int max_new_columns;
 474         int mapping_idx;
 475         int i, seen_this, is_commit_in_columns;
 476
 477         /*
 478          * Swap graph->columns with graph->new_columns
 479          * graph->columns contains the state for the previous commit,
 480          * and new_columns now contains the state for our commit.
 481          *
 482          * We'll re-use the old columns array as storage to compute the new
 483          * columns list for the commit after this one.
 484          */
 485         tmp_columns = graph->columns;
 486         graph->columns = graph->new_columns;
 487         graph->num_columns = graph->num_new_columns;
 488
 489         graph->new_columns = tmp_columns;
 490         graph->num_new_columns = 0;
 491
 492         /*
 493          * Now update new_columns and mapping with the information for the
 494          * commit after this one.
 495          *
 496          * First, make sure we have enough room.  At most, there will
 497          * be graph->num_columns + graph->num_parents columns for the next
 498          * commit.
 499          */
 500         max_new_columns = graph->num_columns + graph->num_parents;
 501         graph_ensure_capacity(graph, max_new_columns);
 502
 503         /*
 504          * Clear out graph->mapping
 505          */
 506         graph->mapping_size = 2 * max_new_columns;
 507         for (i = 0; i < graph->mapping_size; i++)
 508                 graph->mapping[i] = -1;
 509
 510         /*
 511          * Populate graph->new_columns and graph->mapping
 512          *
 513          * Some of the parents of this commit may already be in
 514          * graph->columns.  If so, graph->new_columns should only contain a
 515          * single entry for each such commit.  graph->mapping should
 516          * contain information about where each current branch line is
 517          * supposed to end up after the collapsing is performed.
 518          */
 519         seen_this = 0;
 520         mapping_idx = 0;
 521         is_commit_in_columns = 1;
 522         for (i = 0; i <= graph->num_columns; i++) {
 523                 struct commit *col_commit;
 524                 if (i == graph->num_columns) {
 525                         if (seen_this)
 526                                 break;
 527                         is_commit_in_columns = 0;
 528                         col_commit = graph->commit;
 529                 } else {
 530                         col_commit = graph->columns[i].commit;
 531                 }
 532
 533                 if (col_commit == graph->commit) {
 534                         int old_mapping_idx = mapping_idx;
 535                         seen_this = 1;
 536                         graph->commit_index = i;
 537                         for (parent = first_interesting_parent(graph);
 538                              parent;
 539                              parent = next_interesting_parent(graph, parent)) {
 540                                 /*
 541                                  * If this is a merge, or the start of a new
 542                                  * childless column, increment the current
 543                                  * color.
 544                                  */
 545                                 if (graph->num_parents > 1 ||
 546                                     !is_commit_in_columns) {
 547                                         graph_increment_column_color(graph);
 548                                 }
 549                                 graph_insert_into_new_columns(graph,
 550                                                               parent->item,
 551                                                               &mapping_idx);
 552                         }
 553                         /*
 554                          * We always need to increment mapping_idx by at
 555                          * least 2, even if it has no interesting parents.
 556                          * The current commit always takes up at least 2
 557                          * spaces.
 558                          */
 559                         if (mapping_idx == old_mapping_idx)
 560                                 mapping_idx += 2;
 561                 } else {
 562                         graph_insert_into_new_columns(graph, col_commit,
 563                                                       &mapping_idx);
 564                 }
 565         }
 566
 567         /*
 568          * Shrink mapping_size to be the minimum necessary
 569          */
 570         while (graph->mapping_size > 1 &&
 571                graph->mapping[graph->mapping_size - 1] < 0)
 572                 graph->mapping_size--;
 573
 574         /*
 575          * Compute graph->width for this commit
 576          */
 577         graph_update_width(graph, is_commit_in_columns);
 578 }
 579
 580 void graph_update(struct git_graph *graph, struct commit *commit)
 581 {
 582         struct commit_list *parent;
 583
 584         /*
 585          * Set the new commit
 586          */
 587         graph->commit = commit;
 588
 589         /*
 590          * Count how many interesting parents this commit has
 591          */
 592         graph->num_parents = 0;
 593         for (parent = first_interesting_parent(graph);
 594              parent;
 595              parent = next_interesting_parent(graph, parent))
 596         {
 597                 graph->num_parents++;
 598         }
 599
 600         /*
 601          * Store the old commit_index in prev_commit_index.
 602          * graph_update_columns() will update graph->commit_index for this
 603          * commit.
 604          */
 605         graph->prev_commit_index = graph->commit_index;
 606
 607         /*
 608          * Call graph_update_columns() to update
 609          * columns, new_columns, and mapping.
 610          */
 611         graph_update_columns(graph);
 612
 613         graph->expansion_row = 0;
 614
 615         /*
 616          * Update graph->state.
 617          * Note that we don't call graph_update_state() here, since
 618          * we don't want to update graph->prev_state.  No line for
 619          * graph->state was ever printed.
 620          *
 621          * If the previous commit didn't get to the GRAPH_PADDING state,
 622          * it never finished its output.  Goto GRAPH_SKIP, to print out
 623          * a line to indicate that portion of the graph is missing.
 624          *
 625          * If there are 3 or more parents, we may need to print extra rows
 626          * before the commit, to expand the branch lines around it and make
 627          * room for it.  We need to do this only if there is a branch row
 628          * (or more) to the right of this commit.
 629          *
 630          * If there are less than 3 parents, we can immediately print the
 631          * commit line.
 632          */
 633         if (graph->state != GRAPH_PADDING)
 634                 graph->state = GRAPH_SKIP;
 635         else if (graph->num_parents >= 3 &&
 636                  graph->commit_index < (graph->num_columns - 1))
 637                 graph->state = GRAPH_PRE_COMMIT;
 638         else
 639                 graph->state = GRAPH_COMMIT;
 640 }
 641
 642 static int graph_is_mapping_correct(struct git_graph *graph)
 643 {
 644         int i;
 645
 646         /*
 647          * The mapping is up to date if each entry is at its target,
 648          * or is 1 greater than its target.
 649          * (If it is 1 greater than the target, '/' will be printed, so it
 650          * will look correct on the next row.)
 651          */
 652         for (i = 0; i < graph->mapping_size; i++) {
 653                 int target = graph->mapping[i];
 654                 if (target < 0)
 655                         continue;
 656                 if (target == (i / 2))
 657                         continue;
 658                 return 0;
 659         }
 660
 661         return 1;
 662 }
 663
 664 static void graph_pad_horizontally(struct git_graph *graph, struct strbuf *sb,
 665                                    int chars_written)
 666 {
 667         /*
 668          * Add additional spaces to the end of the strbuf, so that all
 669          * lines for a particular commit have the same width.
 670          *
 671          * This way, fields printed to the right of the graph will remain
 672          * aligned for the entire commit.
 673          */
 674         int extra;
 675         if (chars_written >= graph->width)
 676                 return;
 677
 678         extra = graph->width - chars_written;
 679         strbuf_addf(sb, "%*s", (int) extra, "");
 680 }
 681
 682 static void graph_output_padding_line(struct git_graph *graph,
 683                                       struct strbuf *sb)
 684 {
 685         int i;
 686
 687         /*
 688          * We could conceivable be called with a NULL commit
 689          * if our caller has a bug, and invokes graph_next_line()
 690          * immediately after graph_init(), without first calling
 691          * graph_update().  Return without outputting anything in this
 692          * case.
 693          */
 694         if (!graph->commit)
 695                 return;
 696
 697         /*
 698          * Output a padding row, that leaves all branch lines unchanged
 699          */
 700         for (i = 0; i < graph->num_new_columns; i++) {
 701                 strbuf_write_column(sb, &graph->new_columns[i], '|');
 702                 strbuf_addch(sb, ' ');
 703         }
 704
 705         graph_pad_horizontally(graph, sb, graph->num_new_columns * 2);
 706 }
 707
 708 static void graph_output_skip_line(struct git_graph *graph, struct strbuf *sb)
 709 {
 710         /*
 711          * Output an ellipsis to indicate that a portion
 712          * of the graph is missing.
 713          */
 714         strbuf_addstr(sb, "...");
 715         graph_pad_horizontally(graph, sb, 3);
 716
 717         if (graph->num_parents >= 3 &&
 718             graph->commit_index < (graph->num_columns - 1))
 719                 graph_update_state(graph, GRAPH_PRE_COMMIT);
 720         else
 721                 graph_update_state(graph, GRAPH_COMMIT);
 722 }
 723
 724 static void graph_output_pre_commit_line(struct git_graph *graph,
 725                                          struct strbuf *sb)
 726 {
 727         int num_expansion_rows;
 728         int i, seen_this;
 729         int chars_written;
 730
 731         /*
 732          * This function formats a row that increases the space around a commit
 733          * with multiple parents, to make room for it.  It should only be
 734          * called when there are 3 or more parents.
 735          *
 736          * We need 2 extra rows for every parent over 2.
 737          */
 738         assert(graph->num_parents >= 3);
 739         num_expansion_rows = (graph->num_parents - 2) * 2;
 740
 741         /*
 742          * graph->expansion_row tracks the current expansion row we are on.
 743          * It should be in the range [0, num_expansion_rows - 1]
 744          */
 745         assert(0 <= graph->expansion_row &&
 746                graph->expansion_row < num_expansion_rows);
 747
 748         /*
 749          * Output the row
 750          */
 751         seen_this = 0;
 752         chars_written = 0;
 753         for (i = 0; i < graph->num_columns; i++) {
 754                 struct column *col = &graph->columns[i];
 755                 if (col->commit == graph->commit) {
 756                         seen_this = 1;
 757                         strbuf_write_column(sb, col, '|');
 758                         strbuf_addf(sb, "%*s", graph->expansion_row, "");
 759                         chars_written += 1 + graph->expansion_row;
 760                 } else if (seen_this && (graph->expansion_row == 0)) {
 761                         /*
 762                          * This is the first line of the pre-commit output.
 763                          * If the previous commit was a merge commit and
 764                          * ended in the GRAPH_POST_MERGE state, all branch
 765                          * lines after graph->prev_commit_index were
 766                          * printed as "\" on the previous line.  Continue
 767                          * to print them as "\" on this line.  Otherwise,
 768                          * print the branch lines as "|".
 769                          */
 770                         if (graph->prev_state == GRAPH_POST_MERGE &&
 771                             graph->prev_commit_index < i)
 772                                 strbuf_write_column(sb, col, '\\');
 773                         else
 774                                 strbuf_write_column(sb, col, '|');
 775                         chars_written++;
 776                 } else if (seen_this && (graph->expansion_row > 0)) {
 777                         strbuf_write_column(sb, col, '\\');
 778                         chars_written++;
 779                 } else {
 780                         strbuf_write_column(sb, col, '|');
 781                         chars_written++;
 782                 }
 783                 strbuf_addch(sb, ' ');
 784                 chars_written++;
 785         }
 786
 787         graph_pad_horizontally(graph, sb, chars_written);
 788
 789         /*
 790          * Increment graph->expansion_row,
 791          * and move to state GRAPH_COMMIT if necessary
 792          */
 793         graph->expansion_row++;
 794         if (graph->expansion_row >= num_expansion_rows)
 795                 graph_update_state(graph, GRAPH_COMMIT);
 796 }
 797
 798 static void graph_output_commit_char(struct git_graph *graph, struct strbuf *sb)
 799 {
 800         /*
 801          * For boundary commits, print 'o'
 802          * (We should only see boundary commits when revs->boundary is set.)
 803          */
 804         if (graph->commit->object.flags & BOUNDARY) {
 805                 assert(graph->revs->boundary);
 806                 strbuf_addch(sb, 'o');
 807                 return;
 808         }
 809
 810         /*
 811          * get_revision_mark() handles all other cases without assert()
 812          */
 813         strbuf_addstr(sb, get_revision_mark(graph->revs, graph->commit));
 814 }
 815
 816 /*
 817  * Draw an octopus merge and return the number of characters written.
 818  */
 819 static int graph_draw_octopus_merge(struct git_graph *graph,
 820                                     struct strbuf *sb)
 821 {
 822         /*
 823          * Here dashless_commits represents the number of parents
 824          * which don't need to have dashes (because their edges fit
 825          * neatly under the commit).
 826          */
 827         const int dashless_commits = 2;
 828         int col_num, i;
 829         int num_dashes =
 830                 ((graph->num_parents - dashless_commits) * 2) - 1;
 831         for (i = 0; i < num_dashes; i++) {
 832                 col_num = (i / 2) + dashless_commits;
 833                 strbuf_write_column(sb, &graph->new_columns[col_num], '-');
 834         }
 835         col_num = (i / 2) + dashless_commits;
 836         strbuf_write_column(sb, &graph->new_columns[col_num], '.');
 837         return num_dashes + 1;
 838 }
 839
 840 static void graph_output_commit_line(struct git_graph *graph, struct strbuf *sb)
 841 {
 842         int seen_this = 0;
 843         int i, chars_written;
 844
 845         /*
 846          * Output the row containing this commit
 847          * Iterate up to and including graph->num_columns,
 848          * since the current commit may not be in any of the existing
 849          * columns.  (This happens when the current commit doesn't have any
 850          * children that we have already processed.)
 851          */
 852         seen_this = 0;
 853         chars_written = 0;
 854         for (i = 0; i <= graph->num_columns; i++) {
 855                 struct column *col = &graph->columns[i];
 856                 struct commit *col_commit;
 857                 if (i == graph->num_columns) {
 858                         if (seen_this)
 859                                 break;
 860                         col_commit = graph->commit;
 861                 } else {
 862                         col_commit = graph->columns[i].commit;
 863                 }
 864
 865                 if (col_commit == graph->commit) {
 866                         seen_this = 1;
 867                         graph_output_commit_char(graph, sb);
 868                         chars_written++;
 869
 870                         if (graph->num_parents > 2)
 871                                 chars_written += graph_draw_octopus_merge(graph,
 872                                                                           sb);
 873                 } else if (seen_this && (graph->num_parents > 2)) {
 874                         strbuf_write_column(sb, col, '\\');
 875                         chars_written++;
 876                 } else if (seen_this && (graph->num_parents == 2)) {
 877                         /*
 878                          * This is a 2-way merge commit.
 879                          * There is no GRAPH_PRE_COMMIT stage for 2-way
 880                          * merges, so this is the first line of output
 881                          * for this commit.  Check to see what the previous
 882                          * line of output was.
 883                          *
 884                          * If it was GRAPH_POST_MERGE, the branch line
 885                          * coming into this commit may have been '\',
 886                          * and not '|' or '/'.  If so, output the branch
 887                          * line as '\' on this line, instead of '|'.  This
 888                          * makes the output look nicer.
 889                          */
 890                         if (graph->prev_state == GRAPH_POST_MERGE &&
 891                             graph->prev_commit_index < i)
 892                                 strbuf_write_column(sb, col, '\\');
 893                         else
 894                                 strbuf_write_column(sb, col, '|');
 895                         chars_written++;
 896                 } else {
 897                         strbuf_write_column(sb, col, '|');
 898                         chars_written++;
 899                 }
 900                 strbuf_addch(sb, ' ');
 901                 chars_written++;
 902         }
 903
 904         graph_pad_horizontally(graph, sb, chars_written);
 905
 906         /*
 907          * Update graph->state
 908          */
 909         if (graph->num_parents > 1)
 910                 graph_update_state(graph, GRAPH_POST_MERGE);
 911         else if (graph_is_mapping_correct(graph))
 912                 graph_update_state(graph, GRAPH_PADDING);
 913         else
 914                 graph_update_state(graph, GRAPH_COLLAPSING);
 915 }
 916
 917 static struct column *find_new_column_by_commit(struct git_graph *graph,
 918                                                 struct commit *commit)
 919 {
 920         int i;
 921         for (i = 0; i < graph->num_new_columns; i++) {
 922                 if (graph->new_columns[i].commit == commit)
 923                         return &graph->new_columns[i];
 924         }
 925         return NULL;
 926 }
 927
 928 static void graph_output_post_merge_line(struct git_graph *graph, struct strbuf *sb)
 929 {
 930         int seen_this = 0;
 931         int i, j, chars_written;
 932
 933         /*
 934          * Output the post-merge row
 935          */
 936         chars_written = 0;
 937         for (i = 0; i <= graph->num_columns; i++) {
 938                 struct column *col = &graph->columns[i];
 939                 struct commit *col_commit;
 940                 if (i == graph->num_columns) {
 941                         if (seen_this)
 942                                 break;
 943                         col_commit = graph->commit;
 944                 } else {
 945                         col_commit = col->commit;
 946                 }
 947
 948                 if (col_commit == graph->commit) {
 949                         /*
 950                          * Since the current commit is a merge find
 951                          * the columns for the parent commits in
 952                          * new_columns and use those to format the
 953                          * edges.
 954                          */
 955                         struct commit_list *parents = NULL;
 956                         struct column *par_column;
 957                         seen_this = 1;
 958                         parents = first_interesting_parent(graph);
 959                         assert(parents);
 960                         par_column = find_new_column_by_commit(graph, parents->item);
 961                         assert(par_column);
 962
 963                         strbuf_write_column(sb, par_column, '|');
 964                         chars_written++;
 965                         for (j = 0; j < graph->num_parents - 1; j++) {
 966                                 parents = next_interesting_parent(graph, parents);
 967                                 assert(parents);
 968                                 par_column = find_new_column_by_commit(graph, parents->item);
 969                                 assert(par_column);
 970                                 strbuf_write_column(sb, par_column, '\\');
 971                                 strbuf_addch(sb, ' ');
 972                         }
 973                         chars_written += j * 2;
 974                 } else if (seen_this) {
 975                         strbuf_write_column(sb, col, '\\');
 976                         strbuf_addch(sb, ' ');
 977                         chars_written += 2;
 978                 } else {
 979                         strbuf_write_column(sb, col, '|');
 980                         strbuf_addch(sb, ' ');
 981                         chars_written += 2;
 982                 }
 983         }
 984
 985         graph_pad_horizontally(graph, sb, chars_written);
 986
 987         /*
 988          * Update graph->state
 989          */
 990         if (graph_is_mapping_correct(graph))
 991                 graph_update_state(graph, GRAPH_PADDING);
 992         else
 993                 graph_update_state(graph, GRAPH_COLLAPSING);
 994 }
 995
 996 static void graph_output_collapsing_line(struct git_graph *graph, struct strbuf *sb)
 997 {
 998         int i;
 999         int *tmp_mapping;
1000         short used_horizontal = 0;
1001         int horizontal_edge = -1;
1002         int horizontal_edge_target = -1;
1003
1004         /*
1005          * Clear out the new_mapping array
1006          */
1007         for (i = 0; i < graph->mapping_size; i++)
1008                 graph->new_mapping[i] = -1;
1009
1010         for (i = 0; i < graph->mapping_size; i++) {
1011                 int target = graph->mapping[i];
1012                 if (target < 0)
1013                         continue;
1014
1015                 /*
1016                  * Since update_columns() always inserts the leftmost
1017                  * column first, each branch's target location should
1018                  * always be either its current location or to the left of
1019                  * its current location.
1020                  *
1021                  * We never have to move branches to the right.  This makes
1022                  * the graph much more legible, since whenever branches
1023                  * cross, only one is moving directions.
1024                  */
1025                 assert(target * 2 <= i);
1026
1027                 if (target * 2 == i) {
1028                         /*
1029                          * This column is already in the
1030                          * correct place
1031                          */
1032                         assert(graph->new_mapping[i] == -1);
1033                         graph->new_mapping[i] = target;
1034                 } else if (graph->new_mapping[i - 1] < 0) {
1035                         /*
1036                          * Nothing is to the left.
1037                          * Move to the left by one
1038                          */
1039                         graph->new_mapping[i - 1] = target;
1040                         /*
1041                          * If there isn't already an edge moving horizontally
1042                          * select this one.
1043                          */
1044                         if (horizontal_edge == -1) {
1045                                 int j;
1046                                 horizontal_edge = i;
1047                                 horizontal_edge_target = target;
1048                                 /*
1049                                  * The variable target is the index of the graph
1050                                  * column, and therefore target*2+3 is the
1051                                  * actual screen column of the first horizontal
1052                                  * line.
1053                                  */
1054                                 for (j = (target * 2)+3; j < (i - 2); j += 2)
1055                                         graph->new_mapping[j] = target;
1056                         }
1057                 } else if (graph->new_mapping[i - 1] == target) {
1058                         /*
1059                          * There is a branch line to our left
1060                          * already, and it is our target.  We
1061                          * combine with this line, since we share
1062                          * the same parent commit.
1063                          *
1064                          * We don't have to add anything to the
1065                          * output or new_mapping, since the
1066                          * existing branch line has already taken
1067                          * care of it.
1068                          */
1069                 } else {
1070                         /*
1071                          * There is a branch line to our left,
1072                          * but it isn't our target.  We need to
1073                          * cross over it.
1074                          *
1075                          * The space just to the left of this
1076                          * branch should always be empty.
1077                          *
1078                          * The branch to the left of that space
1079                          * should be our eventual target.
1080                          */
1081                         assert(graph->new_mapping[i - 1] > target);
1082                         assert(graph->new_mapping[i - 2] < 0);
1083                         assert(graph->new_mapping[i - 3] == target);
1084                         graph->new_mapping[i - 2] = target;
1085                         /*
1086                          * Mark this branch as the horizontal edge to
1087                          * prevent any other edges from moving
1088                          * horizontally.
1089                          */
1090                         if (horizontal_edge == -1)
1091                                 horizontal_edge = i;
1092                 }
1093         }
1094
1095         /*
1096          * The new mapping may be 1 smaller than the old mapping
1097          */
1098         if (graph->new_mapping[graph->mapping_size - 1] < 0)
1099                 graph->mapping_size--;
1100
1101         /*
1102          * Output out a line based on the new mapping info
1103          */
1104         for (i = 0; i < graph->mapping_size; i++) {
1105                 int target = graph->new_mapping[i];
1106                 if (target < 0)
1107                         strbuf_addch(sb, ' ');
1108                 else if (target * 2 == i)
1109                         strbuf_write_column(sb, &graph->new_columns[target], '|');
1110                 else if (target == horizontal_edge_target &&
1111                          i != horizontal_edge - 1) {
1112                                 /*
1113                                  * Set the mappings for all but the
1114                                  * first segment to -1 so that they
1115                                  * won't continue into the next line.
1116                                  */
1117                                 if (i != (target * 2)+3)
1118                                         graph->new_mapping[i] = -1;
1119                                 used_horizontal = 1;
1120                         strbuf_write_column(sb, &graph->new_columns[target], '_');
1121                 } else {
1122                         if (used_horizontal && i < horizontal_edge)
1123                                 graph->new_mapping[i] = -1;
1124                         strbuf_write_column(sb, &graph->new_columns[target], '/');
1125
1126                 }
1127         }
1128
1129         graph_pad_horizontally(graph, sb, graph->mapping_size);
1130
1131         /*
1132          * Swap mapping and new_mapping
1133          */
1134         tmp_mapping = graph->mapping;
1135         graph->mapping = graph->new_mapping;
1136         graph->new_mapping = tmp_mapping;
1137
1138         /*
1139          * If graph->mapping indicates that all of the branch lines
1140          * are already in the correct positions, we are done.
1141          * Otherwise, we need to collapse some branch lines together.
1142          */
1143         if (graph_is_mapping_correct(graph))
1144                 graph_update_state(graph, GRAPH_PADDING);
1145 }
1146
1147 static int graph_next_line(struct git_graph *graph, struct strbuf *sb)
1148 {
1149         switch (graph->state) {
1150         case GRAPH_PADDING:
1151                 graph_output_padding_line(graph, sb);
1152                 return 0;
1153         case GRAPH_SKIP:
1154                 graph_output_skip_line(graph, sb);
1155                 return 0;
1156         case GRAPH_PRE_COMMIT:
1157                 graph_output_pre_commit_line(graph, sb);
1158                 return 0;
1159         case GRAPH_COMMIT:
1160                 graph_output_commit_line(graph, sb);
1161                 return 1;
1162         case GRAPH_POST_MERGE:
1163                 graph_output_post_merge_line(graph, sb);
1164                 return 0;
1165         case GRAPH_COLLAPSING:
1166                 graph_output_collapsing_line(graph, sb);
1167                 return 0;
1168         }
1169
1170         assert(0);
1171         return 0;
1172 }
1173
1174 static void graph_padding_line(struct git_graph *graph, struct strbuf *sb)
1175 {
1176         int i, j;
1177
1178         if (graph->state != GRAPH_COMMIT) {
1179                 graph_next_line(graph, sb);
1180                 return;
1181         }
1182
1183         /*
1184          * Output the row containing this commit
1185          * Iterate up to and including graph->num_columns,
1186          * since the current commit may not be in any of the existing
1187          * columns.  (This happens when the current commit doesn't have any
1188          * children that we have already processed.)
1189          */
1190         for (i = 0; i < graph->num_columns; i++) {
1191                 struct column *col = &graph->columns[i];
1192                 struct commit *col_commit = col->commit;
1193                 if (col_commit == graph->commit) {
1194                         strbuf_write_column(sb, col, '|');
1195
1196                         if (graph->num_parents < 3)
1197                                 strbuf_addch(sb, ' ');
1198                         else {
1199                                 int num_spaces = ((graph->num_parents - 2) * 2);
1200                                 for (j = 0; j < num_spaces; j++)
1201                                         strbuf_addch(sb, ' ');
1202                         }
1203                 } else {
1204                         strbuf_write_column(sb, col, '|');
1205                         strbuf_addch(sb, ' ');
1206                 }
1207         }
1208
1209         graph_pad_horizontally(graph, sb, graph->num_columns);
1210
1211         /*
1212          * Update graph->prev_state since we have output a padding line
1213          */
1214         graph->prev_state = GRAPH_PADDING;
1215 }
1216
1217 int graph_is_commit_finished(struct git_graph const *graph)
1218 {
1219         return (graph->state == GRAPH_PADDING);
1220 }
1221
1222 void graph_show_commit(struct git_graph *graph)
1223 {
1224         struct strbuf msgbuf = STRBUF_INIT;
1225         int shown_commit_line = 0;
1226
1227         if (!graph)
1228                 return;
1229
1230         while (!shown_commit_line && !graph_is_commit_finished(graph)) {
1231                 shown_commit_line = graph_next_line(graph, &msgbuf);
1232                 fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
1233                 if (!shown_commit_line)
1234                         putchar('\n');
1235                 strbuf_setlen(&msgbuf, 0);
1236         }
1237
1238         strbuf_release(&msgbuf);
1239 }
1240
1241 void graph_show_oneline(struct git_graph *graph)
1242 {
1243         struct strbuf msgbuf = STRBUF_INIT;
1244
1245         if (!graph)
1246                 return;
1247
1248         graph_next_line(graph, &msgbuf);
1249         fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
1250         strbuf_release(&msgbuf);
1251 }
1252
1253 void graph_show_padding(struct git_graph *graph)
1254 {
1255         struct strbuf msgbuf = STRBUF_INIT;
1256
1257         if (!graph)
1258                 return;
1259
1260         graph_padding_line(graph, &msgbuf);
1261         fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
1262         strbuf_release(&msgbuf);
1263 }
1264
1265 int graph_show_remainder(struct git_graph *graph)
1266 {
1267         struct strbuf msgbuf = STRBUF_INIT;
1268         int shown = 0;
1269
1270         if (!graph)
1271                 return 0;
1272
1273         if (graph_is_commit_finished(graph))
1274                 return 0;
1275
1276         for (;;) {
1277                 graph_next_line(graph, &msgbuf);
1278                 fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
1279                 strbuf_setlen(&msgbuf, 0);
1280                 shown = 1;
1281
1282                 if (!graph_is_commit_finished(graph))
1283                         putchar('\n');
1284                 else
1285                         break;
1286         }
1287         strbuf_release(&msgbuf);
1288
1289         return shown;
1290 }
1291
1292
1293 static void graph_show_strbuf(struct git_graph *graph, struct strbuf const *sb)
1294 {
1295         char *p;
1296
1297         if (!graph) {
1298                 fwrite(sb->buf, sizeof(char), sb->len, stdout);
1299                 return;
1300         }
1301
1302         /*
1303          * Print the strbuf line by line,
1304          * and display the graph info before each line but the first.
1305          */
1306         p = sb->buf;
1307         while (p) {
1308                 size_t len;
1309                 char *next_p = strchr(p, '\n');
1310                 if (next_p) {
1311                         next_p++;
1312                         len = next_p - p;
1313                 } else {
1314                         len = (sb->buf + sb->len) - p;
1315                 }
1316                 fwrite(p, sizeof(char), len, stdout);
1317                 if (next_p && *next_p != '\0')
1318                         graph_show_oneline(graph);
1319                 p = next_p;
1320         }
1321 }
1322
1323 void graph_show_commit_msg(struct git_graph *graph,
1324                            struct strbuf const *sb)
1325 {
1326         int newline_terminated;
1327
1328         if (!graph) {
1329                 /*
1330                  * If there's no graph, just print the message buffer.
1331                  *
1332                  * The message buffer for CMIT_FMT_ONELINE and
1333                  * CMIT_FMT_USERFORMAT are already missing a terminating
1334                  * newline.  All of the other formats should have it.
1335                  */
1336                 fwrite(sb->buf, sizeof(char), sb->len, stdout);
1337                 return;
1338         }
1339
1340         newline_terminated = (sb->len && sb->buf[sb->len - 1] == '\n');
1341
1342         /*
1343          * Show the commit message
1344          */
1345         graph_show_strbuf(graph, sb);
1346
1347         /*
1348          * If there is more output needed for this commit, show it now
1349          */
1350         if (!graph_is_commit_finished(graph)) {
1351                 /*
1352                  * If sb doesn't have a terminating newline, print one now,
1353                  * so we can start the remainder of the graph output on a
1354                  * new line.
1355                  */
1356                 if (!newline_terminated)
1357                         putchar('\n');
1358
1359                 graph_show_remainder(graph);
1360
1361                 /*
1362                  * If sb ends with a newline, our output should too.
1363                  */
1364                 if (newline_terminated)
1365                         putchar('\n');
1366         }
1367 }