graph.con commit Merge branch 'rt/align-add-i-help-text' (c0588fd)
   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 */
  17static 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 */
  37static 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
  48struct 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
  60enum graph_state {
  61        GRAPH_PADDING,
  62        GRAPH_SKIP,
  63        GRAPH_PRE_COMMIT,
  64        GRAPH_COMMIT,
  65        GRAPH_POST_MERGE,
  66        GRAPH_COLLAPSING
  67};
  68
  69static 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
  80static const char **column_colors;
  81static unsigned short column_colors_max;
  82
  83static 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
 103void graph_set_column_colors(const char **colors, unsigned short colors_max)
 104{
 105        column_colors = colors;
 106        column_colors_max = colors_max;
 107}
 108
 109static const char *column_get_color_code(unsigned short color)
 110{
 111        return column_colors[color];
 112}
 113
 114static 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
 124struct 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
 230static 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
 246static const struct diff_options *default_diffopt;
 247
 248void 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
 258struct 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
 317static 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
 323static 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 */
 342static 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
 361static 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
 384static 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
 407static 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 */
 417static 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
 423static 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
 434static 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
 462static 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
 497static 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
 604void 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
 666static 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
 688static 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
 706static 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
 733int graph_width(struct git_graph *graph)
 734{
 735        return graph->width;
 736}
 737
 738
 739static 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
 755static 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
 829static 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 */
 850static 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
 871static 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
 948static 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
 959static 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
1027static 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
1175int 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
1202static 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
1243int graph_is_commit_finished(struct git_graph const *graph)
1244{
1245        return (graph->state == GRAPH_PADDING);
1246}
1247
1248void 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
1282void 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
1296void 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
1310int 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
1342static 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
1369void 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}