git.oblomov.eu Git - git/blob - graph.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "color.h"
   4 #include "graph.h"
   5 #include "revision.h"
   6 #include "argv-array.h"
   7
   8 /* Internal API */
   9
  10 /*
  11  * Output a padding line in the graph.
  12  * This is similar to graph_next_line().  However, it is guaranteed to
  13  * never print the current commit line.  Instead, if the commit line is
  14  * next, it will simply output a line of vertical padding, extending the
  15  * branch lines downwards, but leaving them otherwise unchanged.
  16  */
  17 static void graph_padding_line(struct git_graph *graph, struct strbuf *sb);
  18
  19 /*
  20  * Print a strbuf.  If the graph is non-NULL, all lines but the first will be
  21  * prefixed with the graph output.
  22  *
  23  * If the strbuf ends with a newline, the output will end after this
  24  * newline.  A new graph line will not be printed after the final newline.
  25  * If the strbuf is empty, no output will be printed.
  26  *
  27  * Since the first line will not include the graph output, the caller is
  28  * responsible for printing this line's graph (perhaps via
  29  * graph_show_commit() or graph_show_oneline()) before calling
  30  * graph_show_strbuf().
  31  *
  32  * Note that unlike some other graph display functions, you must pass the file
  33  * handle directly. It is assumed that this is the same file handle as the
  34  * file specified by the graph diff options. This is necessary so that
  35  * graph_show_strbuf can be called even with a NULL graph.
  36  */
  37 static void graph_show_strbuf(struct git_graph *graph,
  38                               FILE *file,
  39                               struct strbuf const *sb);
  40
  41 /*
  42  * TODO:
  43  * - Limit the number of columns, similar to the way gitk does.
  44  *   If we reach more than a specified number of columns, omit
  45  *   sections of some columns.
  46  */
  47
  48 struct column {
  49         /*
  50          * The parent commit of this column.
  51          */
  52         struct commit *commit;
  53         /*
  54          * The color to (optionally) print this column in.  This is an
  55          * index into column_colors.
  56          */
  57         unsigned short color;
  58 };
  59
  60 enum graph_state {
  61         GRAPH_PADDING,
  62         GRAPH_SKIP,
  63         GRAPH_PRE_COMMIT,
  64         GRAPH_COMMIT,
  65         GRAPH_POST_MERGE,
  66         GRAPH_COLLAPSING
  67 };
  68
  69 static void graph_show_line_prefix(const struct diff_options *diffopt)
  70 {
  71         if (!diffopt || !diffopt->line_prefix)
  72                 return;
  73
  74         fwrite(diffopt->line_prefix,
  75                sizeof(char),
  76                diffopt->line_prefix_length,
  77                diffopt->file);
  78 }
  79
  80 static const char **column_colors;
  81 static unsigned short column_colors_max;
  82
  83 static void parse_graph_colors_config(struct argv_array *colors, const char *string)
  84 {
  85         const char *end, *start;
  86
  87         start = string;
  88         end = string + strlen(string);
  89         while (start < end) {
  90                 const char *comma = strchrnul(start, ',');
  91                 char color[COLOR_MAXLEN];
  92
  93                 if (!color_parse_mem(start, comma - start, color))
  94                         argv_array_push(colors, color);
  95                 else
  96                         warning(_("ignore invalid color '%.*s' in log.graphColors"),
  97                                 (int)(comma - start), start);
  98                 start = comma + 1;
  99         }
 100         argv_array_push(colors, GIT_COLOR_RESET);
 101 }
 102
 103 void graph_set_column_colors(const char **colors, unsigned short colors_max)
 104 {
 105         column_colors = colors;
 106         column_colors_max = colors_max;
 107 }
 108
 109 static const char *column_get_color_code(unsigned short color)
 110 {
 111         return column_colors[color];
 112 }
 113
 114 static void strbuf_write_column(struct strbuf *sb, const struct column *c,
 115                                 char col_char)
 116 {
 117         if (c->color < column_colors_max)
 118                 strbuf_addstr(sb, column_get_color_code(c->color));
 119         strbuf_addch(sb, col_char);
 120         if (c->color < column_colors_max)
 121                 strbuf_addstr(sb, column_get_color_code(column_colors_max));
 122 }
 123
 124 struct git_graph {
 125         /*
 126          * The commit currently being processed
 127          */
 128         struct commit *commit;
 129         /* The rev-info used for the current traversal */
 130         struct rev_info *revs;
 131         /*
 132          * The number of interesting parents that this commit has.
 133          *
 134          * Note that this is not the same as the actual number of parents.
 135          * This count excludes parents that won't be printed in the graph
 136          * output, as determined by graph_is_interesting().
 137          */
 138         int num_parents;
 139         /*
 140          * The width of the graph output for this commit.
 141          * All rows for this commit are padded to this width, so that
 142          * messages printed after the graph output are aligned.
 143          */
 144         int width;
 145         /*
 146          * The next expansion row to print
 147          * when state is GRAPH_PRE_COMMIT
 148          */
 149         int expansion_row;
 150         /*
 151          * The current output state.
 152          * This tells us what kind of line graph_next_line() should output.
 153          */
 154         enum graph_state state;
 155         /*
 156          * The output state for the previous line of output.
 157          * This is primarily used to determine how the first merge line
 158          * should appear, based on the last line of the previous commit.
 159          */
 160         enum graph_state prev_state;
 161         /*
 162          * The index of the column that refers to this commit.
 163          *
 164          * If none of the incoming columns refer to this commit,
 165          * this will be equal to num_columns.
 166          */
 167         int commit_index;
 168         /*
 169          * The commit_index for the previously displayed commit.
 170          *
 171          * This is used to determine how the first line of a merge
 172          * graph output should appear, based on the last line of the
 173          * previous commit.
 174          */
 175         int prev_commit_index;
 176         /*
 177          * The maximum number of columns that can be stored in the columns
 178          * and new_columns arrays.  This is also half the number of entries
 179          * that can be stored in the mapping and new_mapping arrays.
 180          */
 181         int column_capacity;
 182         /*
 183          * The number of columns (also called "branch lines" in some places)
 184          */
 185         int num_columns;
 186         /*
 187          * The number of columns in the new_columns array
 188          */
 189         int num_new_columns;
 190         /*
 191          * The number of entries in the mapping array
 192          */
 193         int mapping_size;
 194         /*
 195          * The column state before we output the current commit.
 196          */
 197         struct column *columns;
 198         /*
 199          * The new column state after we output the current commit.
 200          * Only valid when state is GRAPH_COLLAPSING.
 201          */
 202         struct column *new_columns;
 203         /*
 204          * An array that tracks the current state of each
 205          * character in the output line during state GRAPH_COLLAPSING.
 206          * Each entry is -1 if this character is empty, or a non-negative
 207          * integer if the character contains a branch line.  The value of
 208          * the integer indicates the target position for this branch line.
 209          * (I.e., this array maps the current column positions to their
 210          * desired positions.)
 211          *
 212          * The maximum capacity of this array is always
 213          * sizeof(int) * 2 * column_capacity.
 214          */
 215         int *mapping;
 216         /*
 217          * A temporary array for computing the next mapping state
 218          * while we are outputting a mapping line.  This is stored as part
 219          * of the git_graph simply so we don't have to allocate a new
 220          * temporary array each time we have to output a collapsing line.
 221          */
 222         int *new_mapping;
 223         /*
 224          * The current default column color being used.  This is
 225          * stored as an index into the array column_colors.
 226          */
 227         unsigned short default_column_color;
 228 };
 229
 230 static struct strbuf *diff_output_prefix_callback(struct diff_options *opt, void *data)
 231 {
 232         struct git_graph *graph = data;
 233         static struct strbuf msgbuf = STRBUF_INIT;
 234
 235         assert(opt);
 236
 237         strbuf_reset(&msgbuf);
 238         if (opt->line_prefix)
 239                 strbuf_add(&msgbuf, opt->line_prefix,
 240                            opt->line_prefix_length);
 241         if (graph)
 242                 graph_padding_line(graph, &msgbuf);
 243         return &msgbuf;
 244 }
 245
 246 static const struct diff_options *default_diffopt;
 247
 248 void graph_setup_line_prefix(struct diff_options *diffopt)
 249 {
 250         default_diffopt = diffopt;
 251
 252         /* setup an output prefix callback if necessary */
 253         if (diffopt && !diffopt->output_prefix)
 254                 diffopt->output_prefix = diff_output_prefix_callback;
 255 }
 256
 257
 258 struct git_graph *graph_init(struct rev_info *opt)
 259 {
 260         struct git_graph *graph = xmalloc(sizeof(struct git_graph));
 261
 262         if (!column_colors) {
 263                 char *string;
 264                 if (git_config_get_string("log.graphcolors", &string)) {
 265                         /* not configured -- use default */
 266                         graph_set_column_colors(column_colors_ansi,
 267                                                 column_colors_ansi_max);
 268                 } else {
 269                         static struct argv_array custom_colors = ARGV_ARRAY_INIT;
 270                         argv_array_clear(&custom_colors);
 271                         parse_graph_colors_config(&custom_colors, string);
 272                         free(string);
 273                         /* graph_set_column_colors takes a max-index, not a count */
 274                         graph_set_column_colors(custom_colors.argv,
 275                                                 custom_colors.argc - 1);
 276                 }
 277         }
 278
 279         graph->commit = NULL;
 280         graph->revs = opt;
 281         graph->num_parents = 0;
 282         graph->expansion_row = 0;
 283         graph->state = GRAPH_PADDING;
 284         graph->prev_state = GRAPH_PADDING;
 285         graph->commit_index = 0;
 286         graph->prev_commit_index = 0;
 287         graph->num_columns = 0;
 288         graph->num_new_columns = 0;
 289         graph->mapping_size = 0;
 290         /*
 291          * Start the column color at the maximum value, since we'll
 292          * always increment it for the first commit we output.
 293          * This way we start at 0 for the first commit.
 294          */
 295         graph->default_column_color = column_colors_max - 1;
 296
 297         /*
 298          * Allocate a reasonably large default number of columns
 299          * We'll automatically grow columns later if we need more room.
 300          */
 301         graph->column_capacity = 30;
 302         ALLOC_ARRAY(graph->columns, graph->column_capacity);
 303         ALLOC_ARRAY(graph->new_columns, graph->column_capacity);
 304         ALLOC_ARRAY(graph->mapping, 2 * graph->column_capacity);
 305         ALLOC_ARRAY(graph->new_mapping, 2 * graph->column_capacity);
 306
 307         /*
 308          * The diff output prefix callback, with this we can make
 309          * all the diff output to align with the graph lines.
 310          */
 311         opt->diffopt.output_prefix = diff_output_prefix_callback;
 312         opt->diffopt.output_prefix_data = graph;
 313
 314         return graph;
 315 }
 316
 317 static void graph_update_state(struct git_graph *graph, enum graph_state s)
 318 {
 319         graph->prev_state = graph->state;
 320         graph->state = s;
 321 }
 322
 323 static void graph_ensure_capacity(struct git_graph *graph, int num_columns)
 324 {
 325         if (graph->column_capacity >= num_columns)
 326                 return;
 327
 328         do {
 329                 graph->column_capacity *= 2;
 330         } while (graph->column_capacity < num_columns);
 331
 332         REALLOC_ARRAY(graph->columns, graph->column_capacity);
 333         REALLOC_ARRAY(graph->new_columns, graph->column_capacity);
 334         REALLOC_ARRAY(graph->mapping, graph->column_capacity * 2);
 335         REALLOC_ARRAY(graph->new_mapping, graph->column_capacity * 2);
 336 }
 337
 338 /*
 339  * Returns 1 if the commit will be printed in the graph output,
 340  * and 0 otherwise.
 341  */
 342 static int graph_is_interesting(struct git_graph *graph, struct commit *commit)
 343 {
 344         /*
 345          * If revs->boundary is set, commits whose children have
 346          * been shown are always interesting, even if they have the
 347          * UNINTERESTING or TREESAME flags set.
 348          */
 349         if (graph->revs && graph->revs->boundary) {
 350                 if (commit->object.flags & CHILD_SHOWN)
 351                         return 1;
 352         }
 353
 354         /*
 355          * Otherwise, use get_commit_action() to see if this commit is
 356          * interesting
 357          */
 358         return get_commit_action(graph->revs, commit) == commit_show;
 359 }
 360
 361 static struct commit_list *next_interesting_parent(struct git_graph *graph,
 362                                                    struct commit_list *orig)
 363 {
 364         struct commit_list *list;
 365
 366         /*
 367          * If revs->first_parent_only is set, only the first
 368          * parent is interesting.  None of the others are.
 369          */
 370         if (graph->revs->first_parent_only)
 371                 return NULL;
 372
 373         /*
 374          * Return the next interesting commit after orig
 375          */
 376         for (list = orig->next; list; list = list->next) {
 377                 if (graph_is_interesting(graph, list->item))
 378                         return list;
 379         }
 380
 381         return NULL;
 382 }
 383
 384 static struct commit_list *first_interesting_parent(struct git_graph *graph)
 385 {
 386         struct commit_list *parents = graph->commit->parents;
 387
 388         /*
 389          * If this commit has no parents, ignore it
 390          */
 391         if (!parents)
 392                 return NULL;
 393
 394         /*
 395          * If the first parent is interesting, return it
 396          */
 397         if (graph_is_interesting(graph, parents->item))
 398                 return parents;
 399
 400         /*
 401          * Otherwise, call next_interesting_parent() to get
 402          * the next interesting parent
 403          */
 404         return next_interesting_parent(graph, parents);
 405 }
 406
 407 static unsigned short graph_get_current_column_color(const struct git_graph *graph)
 408 {
 409         if (!want_color(graph->revs->diffopt.use_color))
 410                 return column_colors_max;
 411         return graph->default_column_color;
 412 }
 413
 414 /*
 415  * Update the graph's default column color.
 416  */
 417 static void graph_increment_column_color(struct git_graph *graph)
 418 {
 419         graph->default_column_color = (graph->default_column_color + 1) %
 420                 column_colors_max;
 421 }
 422
 423 static unsigned short graph_find_commit_color(const struct git_graph *graph,
 424                                               const struct commit *commit)
 425 {
 426         int i;
 427         for (i = 0; i < graph->num_columns; i++) {
 428                 if (graph->columns[i].commit == commit)
 429                         return graph->columns[i].color;
 430         }
 431         return graph_get_current_column_color(graph);
 432 }
 433
 434 static void graph_insert_into_new_columns(struct git_graph *graph,
 435                                           struct commit *commit,
 436                                           int *mapping_index)
 437 {
 438         int i;
 439
 440         /*
 441          * If the commit is already in the new_columns list, we don't need to
 442          * add it.  Just update the mapping correctly.
 443          */
 444         for (i = 0; i < graph->num_new_columns; i++) {
 445                 if (graph->new_columns[i].commit == commit) {
 446                         graph->mapping[*mapping_index] = i;
 447                         *mapping_index += 2;
 448                         return;
 449                 }
 450         }
 451
 452         /*
 453          * This commit isn't already in new_columns.  Add it.
 454          */
 455         graph->new_columns[graph->num_new_columns].commit = commit;
 456         graph->new_columns[graph->num_new_columns].color = graph_find_commit_color(graph, commit);
 457         graph->mapping[*mapping_index] = graph->num_new_columns;
 458         *mapping_index += 2;
 459         graph->num_new_columns++;
 460 }
 461
 462 static void graph_update_width(struct git_graph *graph,
 463                                int is_commit_in_existing_columns)
 464 {
 465         /*
 466          * Compute the width needed to display the graph for this commit.
 467          * This is the maximum width needed for any row.  All other rows
 468          * will be padded to this width.
 469          *
 470          * Compute the number of columns in the widest row:
 471          * Count each existing column (graph->num_columns), and each new
 472          * column added by this commit.
 473          */
 474         int max_cols = graph->num_columns + graph->num_parents;
 475
 476         /*
 477          * Even if the current commit has no parents to be printed, it
 478          * still takes up a column for itself.
 479          */
 480         if (graph->num_parents < 1)
 481                 max_cols++;
 482
 483         /*
 484          * We added a column for the current commit as part of
 485          * graph->num_parents.  If the current commit was already in
 486          * graph->columns, then we have double counted it.
 487          */
 488         if (is_commit_in_existing_columns)
 489                 max_cols--;
 490
 491         /*
 492          * Each column takes up 2 spaces
 493          */
 494         graph->width = max_cols * 2;
 495 }
 496
 497 static void graph_update_columns(struct git_graph *graph)
 498 {
 499         struct commit_list *parent;
 500         int max_new_columns;
 501         int mapping_idx;
 502         int i, seen_this, is_commit_in_columns;
 503
 504         /*
 505          * Swap graph->columns with graph->new_columns
 506          * graph->columns contains the state for the previous commit,
 507          * and new_columns now contains the state for our commit.
 508          *
 509          * We'll re-use the old columns array as storage to compute the new
 510          * columns list for the commit after this one.
 511          */
 512         SWAP(graph->columns, graph->new_columns);
 513         graph->num_columns = graph->num_new_columns;
 514         graph->num_new_columns = 0;
 515
 516         /*
 517          * Now update new_columns and mapping with the information for the
 518          * commit after this one.
 519          *
 520          * First, make sure we have enough room.  At most, there will
 521          * be graph->num_columns + graph->num_parents columns for the next
 522          * commit.
 523          */
 524         max_new_columns = graph->num_columns + graph->num_parents;
 525         graph_ensure_capacity(graph, max_new_columns);
 526
 527         /*
 528          * Clear out graph->mapping
 529          */
 530         graph->mapping_size = 2 * max_new_columns;
 531         for (i = 0; i < graph->mapping_size; i++)
 532                 graph->mapping[i] = -1;
 533
 534         /*
 535          * Populate graph->new_columns and graph->mapping
 536          *
 537          * Some of the parents of this commit may already be in
 538          * graph->columns.  If so, graph->new_columns should only contain a
 539          * single entry for each such commit.  graph->mapping should
 540          * contain information about where each current branch line is
 541          * supposed to end up after the collapsing is performed.
 542          */
 543         seen_this = 0;
 544         mapping_idx = 0;
 545         is_commit_in_columns = 1;
 546         for (i = 0; i <= graph->num_columns; i++) {
 547                 struct commit *col_commit;
 548                 if (i == graph->num_columns) {
 549                         if (seen_this)
 550                                 break;
 551                         is_commit_in_columns = 0;
 552                         col_commit = graph->commit;
 553                 } else {
 554                         col_commit = graph->columns[i].commit;
 555                 }
 556
 557                 if (col_commit == graph->commit) {
 558                         int old_mapping_idx = mapping_idx;
 559                         seen_this = 1;
 560                         graph->commit_index = i;
 561                         for (parent = first_interesting_parent(graph);
 562                              parent;
 563                              parent = next_interesting_parent(graph, parent)) {
 564                                 /*
 565                                  * If this is a merge, or the start of a new
 566                                  * childless column, increment the current
 567                                  * color.
 568                                  */
 569                                 if (graph->num_parents > 1 ||
 570                                     !is_commit_in_columns) {
 571                                         graph_increment_column_color(graph);
 572                                 }
 573                                 graph_insert_into_new_columns(graph,
 574                                                               parent->item,
 575                                                               &mapping_idx);
 576                         }
 577                         /*
 578                          * We always need to increment mapping_idx by at
 579                          * least 2, even if it has no interesting parents.
 580                          * The current commit always takes up at least 2
 581                          * spaces.
 582                          */
 583                         if (mapping_idx == old_mapping_idx)
 584                                 mapping_idx += 2;
 585                 } else {
 586                         graph_insert_into_new_columns(graph, col_commit,
 587                                                       &mapping_idx);
 588                 }
 589         }
 590
 591         /*
 592          * Shrink mapping_size to be the minimum necessary
 593          */
 594         while (graph->mapping_size > 1 &&
 595                graph->mapping[graph->mapping_size - 1] < 0)
 596                 graph->mapping_size--;
 597
 598         /*
 599          * Compute graph->width for this commit
 600          */
 601         graph_update_width(graph, is_commit_in_columns);
 602 }
 603
 604 void graph_update(struct git_graph *graph, struct commit *commit)
 605 {
 606         struct commit_list *parent;
 607
 608         /*
 609          * Set the new commit
 610          */
 611         graph->commit = commit;
 612
 613         /*
 614          * Count how many interesting parents this commit has
 615          */
 616         graph->num_parents = 0;
 617         for (parent = first_interesting_parent(graph);
 618              parent;
 619              parent = next_interesting_parent(graph, parent))
 620         {
 621                 graph->num_parents++;
 622         }
 623
 624         /*
 625          * Store the old commit_index in prev_commit_index.
 626          * graph_update_columns() will update graph->commit_index for this
 627          * commit.
 628          */
 629         graph->prev_commit_index = graph->commit_index;
 630
 631         /*
 632          * Call graph_update_columns() to update
 633          * columns, new_columns, and mapping.
 634          */
 635         graph_update_columns(graph);
 636
 637         graph->expansion_row = 0;
 638
 639         /*
 640          * Update graph->state.
 641          * Note that we don't call graph_update_state() here, since
 642          * we don't want to update graph->prev_state.  No line for
 643          * graph->state was ever printed.
 644          *
 645          * If the previous commit didn't get to the GRAPH_PADDING state,
 646          * it never finished its output.  Goto GRAPH_SKIP, to print out
 647          * a line to indicate that portion of the graph is missing.
 648          *
 649          * If there are 3 or more parents, we may need to print extra rows
 650          * before the commit, to expand the branch lines around it and make
 651          * room for it.  We need to do this only if there is a branch row
 652          * (or more) to the right of this commit.
 653          *
 654          * If there are less than 3 parents, we can immediately print the
 655          * commit line.
 656          */
 657         if (graph->state != GRAPH_PADDING)
 658                 graph->state = GRAPH_SKIP;
 659         else if (graph->num_parents >= 3 &&
 660                  graph->commit_index < (graph->num_columns - 1))
 661                 graph->state = GRAPH_PRE_COMMIT;
 662         else
 663                 graph->state = GRAPH_COMMIT;
 664 }
 665
 666 static int graph_is_mapping_correct(struct git_graph *graph)
 667 {
 668         int i;
 669
 670         /*
 671          * The mapping is up to date if each entry is at its target,
 672          * or is 1 greater than its target.
 673          * (If it is 1 greater than the target, '/' will be printed, so it
 674          * will look correct on the next row.)
 675          */
 676         for (i = 0; i < graph->mapping_size; i++) {
 677                 int target = graph->mapping[i];
 678                 if (target < 0)
 679                         continue;
 680                 if (target == (i / 2))
 681                         continue;
 682                 return 0;
 683         }
 684
 685         return 1;
 686 }
 687
 688 static void graph_pad_horizontally(struct git_graph *graph, struct strbuf *sb,
 689                                    int chars_written)
 690 {
 691         /*
 692          * Add additional spaces to the end of the strbuf, so that all
 693          * lines for a particular commit have the same width.
 694          *
 695          * This way, fields printed to the right of the graph will remain
 696          * aligned for the entire commit.
 697          */
 698         int extra;
 699         if (chars_written >= graph->width)
 700                 return;
 701
 702         extra = graph->width - chars_written;
 703         strbuf_addf(sb, "%*s", (int) extra, "");
 704 }
 705
 706 static void graph_output_padding_line(struct git_graph *graph,
 707                                       struct strbuf *sb)
 708 {
 709         int i;
 710
 711         /*
 712          * We could conceivable be called with a NULL commit
 713          * if our caller has a bug, and invokes graph_next_line()
 714          * immediately after graph_init(), without first calling
 715          * graph_update().  Return without outputting anything in this
 716          * case.
 717          */
 718         if (!graph->commit)
 719                 return;
 720
 721         /*
 722          * Output a padding row, that leaves all branch lines unchanged
 723          */
 724         for (i = 0; i < graph->num_new_columns; i++) {
 725                 strbuf_write_column(sb, &graph->new_columns[i], '|');
 726                 strbuf_addch(sb, ' ');
 727         }
 728
 729         graph_pad_horizontally(graph, sb, graph->num_new_columns * 2);
 730 }
 731
 732
 733 int graph_width(struct git_graph *graph)
 734 {
 735         return graph->width;
 736 }
 737
 738
 739 static void graph_output_skip_line(struct git_graph *graph, struct strbuf *sb)
 740 {
 741         /*
 742          * Output an ellipsis to indicate that a portion
 743          * of the graph is missing.
 744          */
 745         strbuf_addstr(sb, "...");
 746         graph_pad_horizontally(graph, sb, 3);
 747
 748         if (graph->num_parents >= 3 &&
 749             graph->commit_index < (graph->num_columns - 1))
 750                 graph_update_state(graph, GRAPH_PRE_COMMIT);
 751         else
 752                 graph_update_state(graph, GRAPH_COMMIT);
 753 }
 754
 755 static void graph_output_pre_commit_line(struct git_graph *graph,
 756                                          struct strbuf *sb)
 757 {
 758         int num_expansion_rows;
 759         int i, seen_this;
 760         int chars_written;
 761
 762         /*
 763          * This function formats a row that increases the space around a commit
 764          * with multiple parents, to make room for it.  It should only be
 765          * called when there are 3 or more parents.
 766          *
 767          * We need 2 extra rows for every parent over 2.
 768          */
 769         assert(graph->num_parents >= 3);
 770         num_expansion_rows = (graph->num_parents - 2) * 2;
 771
 772         /*
 773          * graph->expansion_row tracks the current expansion row we are on.
 774          * It should be in the range [0, num_expansion_rows - 1]
 775          */
 776         assert(0 <= graph->expansion_row &&
 777                graph->expansion_row < num_expansion_rows);
 778
 779         /*
 780          * Output the row
 781          */
 782         seen_this = 0;
 783         chars_written = 0;
 784         for (i = 0; i < graph->num_columns; i++) {
 785                 struct column *col = &graph->columns[i];
 786                 if (col->commit == graph->commit) {
 787                         seen_this = 1;
 788                         strbuf_write_column(sb, col, '|');
 789                         strbuf_addf(sb, "%*s", graph->expansion_row, "");
 790                         chars_written += 1 + graph->expansion_row;
 791                 } else if (seen_this && (graph->expansion_row == 0)) {
 792                         /*
 793                          * This is the first line of the pre-commit output.
 794                          * If the previous commit was a merge commit and
 795                          * ended in the GRAPH_POST_MERGE state, all branch
 796                          * lines after graph->prev_commit_index were
 797                          * printed as "\" on the previous line.  Continue
 798                          * to print them as "\" on this line.  Otherwise,
 799                          * print the branch lines as "|".
 800                          */
 801                         if (graph->prev_state == GRAPH_POST_MERGE &&
 802                             graph->prev_commit_index < i)
 803                                 strbuf_write_column(sb, col, '\\');
 804                         else
 805                                 strbuf_write_column(sb, col, '|');
 806                         chars_written++;
 807                 } else if (seen_this && (graph->expansion_row > 0)) {
 808                         strbuf_write_column(sb, col, '\\');
 809                         chars_written++;
 810                 } else {
 811                         strbuf_write_column(sb, col, '|');
 812                         chars_written++;
 813                 }
 814                 strbuf_addch(sb, ' ');
 815                 chars_written++;
 816         }
 817
 818         graph_pad_horizontally(graph, sb, chars_written);
 819
 820         /*
 821          * Increment graph->expansion_row,
 822          * and move to state GRAPH_COMMIT if necessary
 823          */
 824         graph->expansion_row++;
 825         if (graph->expansion_row >= num_expansion_rows)
 826                 graph_update_state(graph, GRAPH_COMMIT);
 827 }
 828
 829 static void graph_output_commit_char(struct git_graph *graph, struct strbuf *sb)
 830 {
 831         /*
 832          * For boundary commits, print 'o'
 833          * (We should only see boundary commits when revs->boundary is set.)
 834          */
 835         if (graph->commit->object.flags & BOUNDARY) {
 836                 assert(graph->revs->boundary);
 837                 strbuf_addch(sb, 'o');
 838                 return;
 839         }
 840
 841         /*
 842          * get_revision_mark() handles all other cases without assert()
 843          */
 844         strbuf_addstr(sb, get_revision_mark(graph->revs, graph->commit));
 845 }
 846
 847 /*
 848  * Draw an octopus merge and return the number of characters written.
 849  */
 850 static int graph_draw_octopus_merge(struct git_graph *graph,
 851                                     struct strbuf *sb)
 852 {
 853         /*
 854          * Here dashless_commits represents the number of parents
 855          * which don't need to have dashes (because their edges fit
 856          * neatly under the commit).
 857          */
 858         const int dashless_commits = 2;
 859         int col_num, i;
 860         int num_dashes =
 861                 ((graph->num_parents - dashless_commits) * 2) - 1;
 862         for (i = 0; i < num_dashes; i++) {
 863                 col_num = (i / 2) + dashless_commits + graph->commit_index;
 864                 strbuf_write_column(sb, &graph->new_columns[col_num], '-');
 865         }
 866         col_num = (i / 2) + dashless_commits + graph->commit_index;
 867         strbuf_write_column(sb, &graph->new_columns[col_num], '.');
 868         return num_dashes + 1;
 869 }
 870
 871 static void graph_output_commit_line(struct git_graph *graph, struct strbuf *sb)
 872 {
 873         int seen_this = 0;
 874         int i, chars_written;
 875
 876         /*
 877          * Output the row containing this commit
 878          * Iterate up to and including graph->num_columns,
 879          * since the current commit may not be in any of the existing
 880          * columns.  (This happens when the current commit doesn't have any
 881          * children that we have already processed.)
 882          */
 883         seen_this = 0;
 884         chars_written = 0;
 885         for (i = 0; i <= graph->num_columns; i++) {
 886                 struct column *col = &graph->columns[i];
 887                 struct commit *col_commit;
 888                 if (i == graph->num_columns) {
 889                         if (seen_this)
 890                                 break;
 891                         col_commit = graph->commit;
 892                 } else {
 893                         col_commit = graph->columns[i].commit;
 894                 }
 895
 896                 if (col_commit == graph->commit) {
 897                         seen_this = 1;
 898                         graph_output_commit_char(graph, sb);
 899                         chars_written++;
 900
 901                         if (graph->num_parents > 2)
 902                                 chars_written += graph_draw_octopus_merge(graph,
 903                                                                           sb);
 904                 } else if (seen_this && (graph->num_parents > 2)) {
 905                         strbuf_write_column(sb, col, '\\');
 906                         chars_written++;
 907                 } else if (seen_this && (graph->num_parents == 2)) {
 908                         /*
 909                          * This is a 2-way merge commit.
 910                          * There is no GRAPH_PRE_COMMIT stage for 2-way
 911                          * merges, so this is the first line of output
 912                          * for this commit.  Check to see what the previous
 913                          * line of output was.
 914                          *
 915                          * If it was GRAPH_POST_MERGE, the branch line
 916                          * coming into this commit may have been '\',
 917                          * and not '|' or '/'.  If so, output the branch
 918                          * line as '\' on this line, instead of '|'.  This
 919                          * makes the output look nicer.
 920                          */
 921                         if (graph->prev_state == GRAPH_POST_MERGE &&
 922                             graph->prev_commit_index < i)
 923                                 strbuf_write_column(sb, col, '\\');
 924                         else
 925                                 strbuf_write_column(sb, col, '|');
 926                         chars_written++;
 927                 } else {
 928                         strbuf_write_column(sb, col, '|');
 929                         chars_written++;
 930                 }
 931                 strbuf_addch(sb, ' ');
 932                 chars_written++;
 933         }
 934
 935         graph_pad_horizontally(graph, sb, chars_written);
 936
 937         /*
 938          * Update graph->state
 939          */
 940         if (graph->num_parents > 1)
 941                 graph_update_state(graph, GRAPH_POST_MERGE);
 942         else if (graph_is_mapping_correct(graph))
 943                 graph_update_state(graph, GRAPH_PADDING);
 944         else
 945                 graph_update_state(graph, GRAPH_COLLAPSING);
 946 }
 947
 948 static struct column *find_new_column_by_commit(struct git_graph *graph,
 949                                                 struct commit *commit)
 950 {
 951         int i;
 952         for (i = 0; i < graph->num_new_columns; i++) {
 953                 if (graph->new_columns[i].commit == commit)
 954                         return &graph->new_columns[i];
 955         }
 956         return NULL;
 957 }
 958
 959 static void graph_output_post_merge_line(struct git_graph *graph, struct strbuf *sb)
 960 {
 961         int seen_this = 0;
 962         int i, j, chars_written;
 963
 964         /*
 965          * Output the post-merge row
 966          */
 967         chars_written = 0;
 968         for (i = 0; i <= graph->num_columns; i++) {
 969                 struct column *col = &graph->columns[i];
 970                 struct commit *col_commit;
 971                 if (i == graph->num_columns) {
 972                         if (seen_this)
 973                                 break;
 974                         col_commit = graph->commit;
 975                 } else {
 976                         col_commit = col->commit;
 977                 }
 978
 979                 if (col_commit == graph->commit) {
 980                         /*
 981                          * Since the current commit is a merge find
 982                          * the columns for the parent commits in
 983                          * new_columns and use those to format the
 984                          * edges.
 985                          */
 986                         struct commit_list *parents = NULL;
 987                         struct column *par_column;
 988                         seen_this = 1;
 989                         parents = first_interesting_parent(graph);
 990                         assert(parents);
 991                         par_column = find_new_column_by_commit(graph, parents->item);
 992                         assert(par_column);
 993
 994                         strbuf_write_column(sb, par_column, '|');
 995                         chars_written++;
 996                         for (j = 0; j < graph->num_parents - 1; j++) {
 997                                 parents = next_interesting_parent(graph, parents);
 998                                 assert(parents);
 999                                 par_column = find_new_column_by_commit(graph, parents->item);
1000                                 assert(par_column);
1001                                 strbuf_write_column(sb, par_column, '\\');
1002                                 strbuf_addch(sb, ' ');
1003                         }
1004                         chars_written += j * 2;
1005                 } else if (seen_this) {
1006                         strbuf_write_column(sb, col, '\\');
1007                         strbuf_addch(sb, ' ');
1008                         chars_written += 2;
1009                 } else {
1010                         strbuf_write_column(sb, col, '|');
1011                         strbuf_addch(sb, ' ');
1012                         chars_written += 2;
1013                 }
1014         }
1015
1016         graph_pad_horizontally(graph, sb, chars_written);
1017
1018         /*
1019          * Update graph->state
1020          */
1021         if (graph_is_mapping_correct(graph))
1022                 graph_update_state(graph, GRAPH_PADDING);
1023         else
1024                 graph_update_state(graph, GRAPH_COLLAPSING);
1025 }
1026
1027 static void graph_output_collapsing_line(struct git_graph *graph, struct strbuf *sb)
1028 {
1029         int i;
1030         short used_horizontal = 0;
1031         int horizontal_edge = -1;
1032         int horizontal_edge_target = -1;
1033
1034         /*
1035          * Clear out the new_mapping array
1036          */
1037         for (i = 0; i < graph->mapping_size; i++)
1038                 graph->new_mapping[i] = -1;
1039
1040         for (i = 0; i < graph->mapping_size; i++) {
1041                 int target = graph->mapping[i];
1042                 if (target < 0)
1043                         continue;
1044
1045                 /*
1046                  * Since update_columns() always inserts the leftmost
1047                  * column first, each branch's target location should
1048                  * always be either its current location or to the left of
1049                  * its current location.
1050                  *
1051                  * We never have to move branches to the right.  This makes
1052                  * the graph much more legible, since whenever branches
1053                  * cross, only one is moving directions.
1054                  */
1055                 assert(target * 2 <= i);
1056
1057                 if (target * 2 == i) {
1058                         /*
1059                          * This column is already in the
1060                          * correct place
1061                          */
1062                         assert(graph->new_mapping[i] == -1);
1063                         graph->new_mapping[i] = target;
1064                 } else if (graph->new_mapping[i - 1] < 0) {
1065                         /*
1066                          * Nothing is to the left.
1067                          * Move to the left by one
1068                          */
1069                         graph->new_mapping[i - 1] = target;
1070                         /*
1071                          * If there isn't already an edge moving horizontally
1072                          * select this one.
1073                          */
1074                         if (horizontal_edge == -1) {
1075                                 int j;
1076                                 horizontal_edge = i;
1077                                 horizontal_edge_target = target;
1078                                 /*
1079                                  * The variable target is the index of the graph
1080                                  * column, and therefore target*2+3 is the
1081                                  * actual screen column of the first horizontal
1082                                  * line.
1083                                  */
1084                                 for (j = (target * 2)+3; j < (i - 2); j += 2)
1085                                         graph->new_mapping[j] = target;
1086                         }
1087                 } else if (graph->new_mapping[i - 1] == target) {
1088                         /*
1089                          * There is a branch line to our left
1090                          * already, and it is our target.  We
1091                          * combine with this line, since we share
1092                          * the same parent commit.
1093                          *
1094                          * We don't have to add anything to the
1095                          * output or new_mapping, since the
1096                          * existing branch line has already taken
1097                          * care of it.
1098                          */
1099                 } else {
1100                         /*
1101                          * There is a branch line to our left,
1102                          * but it isn't our target.  We need to
1103                          * cross over it.
1104                          *
1105                          * The space just to the left of this
1106                          * branch should always be empty.
1107                          *
1108                          * The branch to the left of that space
1109                          * should be our eventual target.
1110                          */
1111                         assert(graph->new_mapping[i - 1] > target);
1112                         assert(graph->new_mapping[i - 2] < 0);
1113                         assert(graph->new_mapping[i - 3] == target);
1114                         graph->new_mapping[i - 2] = target;
1115                         /*
1116                          * Mark this branch as the horizontal edge to
1117                          * prevent any other edges from moving
1118                          * horizontally.
1119                          */
1120                         if (horizontal_edge == -1)
1121                                 horizontal_edge = i;
1122                 }
1123         }
1124
1125         /*
1126          * The new mapping may be 1 smaller than the old mapping
1127          */
1128         if (graph->new_mapping[graph->mapping_size - 1] < 0)
1129                 graph->mapping_size--;
1130
1131         /*
1132          * Output out a line based on the new mapping info
1133          */
1134         for (i = 0; i < graph->mapping_size; i++) {
1135                 int target = graph->new_mapping[i];
1136                 if (target < 0)
1137                         strbuf_addch(sb, ' ');
1138                 else if (target * 2 == i)
1139                         strbuf_write_column(sb, &graph->new_columns[target], '|');
1140                 else if (target == horizontal_edge_target &&
1141                          i != horizontal_edge - 1) {
1142                                 /*
1143                                  * Set the mappings for all but the
1144                                  * first segment to -1 so that they
1145                                  * won't continue into the next line.
1146                                  */
1147                                 if (i != (target * 2)+3)
1148                                         graph->new_mapping[i] = -1;
1149                                 used_horizontal = 1;
1150                         strbuf_write_column(sb, &graph->new_columns[target], '_');
1151                 } else {
1152                         if (used_horizontal && i < horizontal_edge)
1153                                 graph->new_mapping[i] = -1;
1154                         strbuf_write_column(sb, &graph->new_columns[target], '/');
1155
1156                 }
1157         }
1158
1159         graph_pad_horizontally(graph, sb, graph->mapping_size);
1160
1161         /*
1162          * Swap mapping and new_mapping
1163          */
1164         SWAP(graph->mapping, graph->new_mapping);
1165
1166         /*
1167          * If graph->mapping indicates that all of the branch lines
1168          * are already in the correct positions, we are done.
1169          * Otherwise, we need to collapse some branch lines together.
1170          */
1171         if (graph_is_mapping_correct(graph))
1172                 graph_update_state(graph, GRAPH_PADDING);
1173 }
1174
1175 int graph_next_line(struct git_graph *graph, struct strbuf *sb)
1176 {
1177         switch (graph->state) {
1178         case GRAPH_PADDING:
1179                 graph_output_padding_line(graph, sb);
1180                 return 0;
1181         case GRAPH_SKIP:
1182                 graph_output_skip_line(graph, sb);
1183                 return 0;
1184         case GRAPH_PRE_COMMIT:
1185                 graph_output_pre_commit_line(graph, sb);
1186                 return 0;
1187         case GRAPH_COMMIT:
1188                 graph_output_commit_line(graph, sb);
1189                 return 1;
1190         case GRAPH_POST_MERGE:
1191                 graph_output_post_merge_line(graph, sb);
1192                 return 0;
1193         case GRAPH_COLLAPSING:
1194                 graph_output_collapsing_line(graph, sb);
1195                 return 0;
1196         }
1197
1198         assert(0);
1199         return 0;
1200 }
1201
1202 static void graph_padding_line(struct git_graph *graph, struct strbuf *sb)
1203 {
1204         int i;
1205         int chars_written = 0;
1206
1207         if (graph->state != GRAPH_COMMIT) {
1208                 graph_next_line(graph, sb);
1209                 return;
1210         }
1211
1212         /*
1213          * Output the row containing this commit
1214          * Iterate up to and including graph->num_columns,
1215          * since the current commit may not be in any of the existing
1216          * columns.  (This happens when the current commit doesn't have any
1217          * children that we have already processed.)
1218          */
1219         for (i = 0; i < graph->num_columns; i++) {
1220                 struct column *col = &graph->columns[i];
1221
1222                 strbuf_write_column(sb, col, '|');
1223                 chars_written++;
1224
1225                 if (col->commit == graph->commit && graph->num_parents > 2) {
1226                         int len = (graph->num_parents - 2) * 2;
1227                         strbuf_addchars(sb, ' ', len);
1228                         chars_written += len;
1229                 } else {
1230                         strbuf_addch(sb, ' ');
1231                         chars_written++;
1232                 }
1233         }
1234
1235         graph_pad_horizontally(graph, sb, chars_written);
1236
1237         /*
1238          * Update graph->prev_state since we have output a padding line
1239          */
1240         graph->prev_state = GRAPH_PADDING;
1241 }
1242
1243 int graph_is_commit_finished(struct git_graph const *graph)
1244 {
1245         return (graph->state == GRAPH_PADDING);
1246 }
1247
1248 void graph_show_commit(struct git_graph *graph)
1249 {
1250         struct strbuf msgbuf = STRBUF_INIT;
1251         int shown_commit_line = 0;
1252
1253         graph_show_line_prefix(default_diffopt);
1254
1255         if (!graph)
1256                 return;
1257
1258         /*
1259          * When showing a diff of a merge against each of its parents, we
1260          * are called once for each parent without graph_update having been
1261          * called.  In this case, simply output a single padding line.
1262          */
1263         if (graph_is_commit_finished(graph)) {
1264                 graph_show_padding(graph);
1265                 shown_commit_line = 1;
1266         }
1267
1268         while (!shown_commit_line && !graph_is_commit_finished(graph)) {
1269                 shown_commit_line = graph_next_line(graph, &msgbuf);
1270                 fwrite(msgbuf.buf, sizeof(char), msgbuf.len,
1271                         graph->revs->diffopt.file);
1272                 if (!shown_commit_line) {
1273                         putc('\n', graph->revs->diffopt.file);
1274                         graph_show_line_prefix(&graph->revs->diffopt);
1275                 }
1276                 strbuf_setlen(&msgbuf, 0);
1277         }
1278
1279         strbuf_release(&msgbuf);
1280 }
1281
1282 void graph_show_oneline(struct git_graph *graph)
1283 {
1284         struct strbuf msgbuf = STRBUF_INIT;
1285
1286         graph_show_line_prefix(default_diffopt);
1287
1288         if (!graph)
1289                 return;
1290
1291         graph_next_line(graph, &msgbuf);
1292         fwrite(msgbuf.buf, sizeof(char), msgbuf.len, graph->revs->diffopt.file);
1293         strbuf_release(&msgbuf);
1294 }
1295
1296 void graph_show_padding(struct git_graph *graph)
1297 {
1298         struct strbuf msgbuf = STRBUF_INIT;
1299
1300         graph_show_line_prefix(default_diffopt);
1301
1302         if (!graph)
1303                 return;
1304
1305         graph_padding_line(graph, &msgbuf);
1306         fwrite(msgbuf.buf, sizeof(char), msgbuf.len, graph->revs->diffopt.file);
1307         strbuf_release(&msgbuf);
1308 }
1309
1310 int graph_show_remainder(struct git_graph *graph)
1311 {
1312         struct strbuf msgbuf = STRBUF_INIT;
1313         int shown = 0;
1314
1315         graph_show_line_prefix(default_diffopt);
1316
1317         if (!graph)
1318                 return 0;
1319
1320         if (graph_is_commit_finished(graph))
1321                 return 0;
1322
1323         for (;;) {
1324                 graph_next_line(graph, &msgbuf);
1325                 fwrite(msgbuf.buf, sizeof(char), msgbuf.len,
1326                         graph->revs->diffopt.file);
1327                 strbuf_setlen(&msgbuf, 0);
1328                 shown = 1;
1329
1330                 if (!graph_is_commit_finished(graph)) {
1331                         putc('\n', graph->revs->diffopt.file);
1332                         graph_show_line_prefix(&graph->revs->diffopt);
1333                 } else {
1334                         break;
1335                 }
1336         }
1337         strbuf_release(&msgbuf);
1338
1339         return shown;
1340 }
1341
1342 static void graph_show_strbuf(struct git_graph *graph,
1343                               FILE *file,
1344                               struct strbuf const *sb)
1345 {
1346         char *p;
1347
1348         /*
1349          * Print the strbuf line by line,
1350          * and display the graph info before each line but the first.
1351          */
1352         p = sb->buf;
1353         while (p) {
1354                 size_t len;
1355                 char *next_p = strchr(p, '\n');
1356                 if (next_p) {
1357                         next_p++;
1358                         len = next_p - p;
1359                 } else {
1360                         len = (sb->buf + sb->len) - p;
1361                 }
1362                 fwrite(p, sizeof(char), len, file);
1363                 if (next_p && *next_p != '\0')
1364                         graph_show_oneline(graph);
1365                 p = next_p;
1366         }
1367 }
1368
1369 void graph_show_commit_msg(struct git_graph *graph,
1370                            FILE *file,
1371                            struct strbuf const *sb)
1372 {
1373         int newline_terminated;
1374
1375         /*
1376          * Show the commit message
1377          */
1378         graph_show_strbuf(graph, file, sb);
1379
1380         if (!graph)
1381                 return;
1382
1383         newline_terminated = (sb->len && sb->buf[sb->len - 1] == '\n');
1384
1385         /*
1386          * If there is more output needed for this commit, show it now
1387          */
1388         if (!graph_is_commit_finished(graph)) {
1389                 /*
1390                  * If sb doesn't have a terminating newline, print one now,
1391                  * so we can start the remainder of the graph output on a
1392                  * new line.
1393                  */
1394                 if (!newline_terminated)
1395                         putc('\n', file);
1396
1397                 graph_show_remainder(graph);
1398
1399                 /*
1400                  * If sb ends with a newline, our output should too.
1401                  */
1402                 if (newline_terminated)
1403                         putc('\n', file);
1404         }
1405 }