graph.con commit wt-status.c: set the committable flag in the collect phase (f3bd35f)
   1#include "cache.h"
   2#include "config.h"
   3#include "commit.h"
   4#include "color.h"
   5#include "graph.h"
   6#include "revision.h"
   7#include "argv-array.h"
   8
   9/* Internal API */
  10
  11/*
  12 * Output a padding line in the graph.
  13 * This is similar to graph_next_line().  However, it is guaranteed to
  14 * never print the current commit line.  Instead, if the commit line is
  15 * next, it will simply output a line of vertical padding, extending the
  16 * branch lines downwards, but leaving them otherwise unchanged.
  17 */
  18static void graph_padding_line(struct git_graph *graph, struct strbuf *sb);
  19
  20/*
  21 * Print a strbuf.  If the graph is non-NULL, all lines but the first will be
  22 * prefixed with the graph output.
  23 *
  24 * If the strbuf ends with a newline, the output will end after this
  25 * newline.  A new graph line will not be printed after the final newline.
  26 * If the strbuf is empty, no output will be printed.
  27 *
  28 * Since the first line will not include the graph output, the caller is
  29 * responsible for printing this line's graph (perhaps via
  30 * graph_show_commit() or graph_show_oneline()) before calling
  31 * graph_show_strbuf().
  32 *
  33 * Note that unlike some other graph display functions, you must pass the file
  34 * handle directly. It is assumed that this is the same file handle as the
  35 * file specified by the graph diff options. This is necessary so that
  36 * graph_show_strbuf can be called even with a NULL graph.
  37 */
  38static void graph_show_strbuf(struct git_graph *graph,
  39                              FILE *file,
  40                              struct strbuf const *sb);
  41
  42/*
  43 * TODO:
  44 * - Limit the number of columns, similar to the way gitk does.
  45 *   If we reach more than a specified number of columns, omit
  46 *   sections of some columns.
  47 */
  48
  49struct column {
  50        /*
  51         * The parent commit of this column.
  52         */
  53        struct commit *commit;
  54        /*
  55         * The color to (optionally) print this column in.  This is an
  56         * index into column_colors.
  57         */
  58        unsigned short color;
  59};
  60
  61enum graph_state {
  62        GRAPH_PADDING,
  63        GRAPH_SKIP,
  64        GRAPH_PRE_COMMIT,
  65        GRAPH_COMMIT,
  66        GRAPH_POST_MERGE,
  67        GRAPH_COLLAPSING
  68};
  69
  70static void graph_show_line_prefix(const struct diff_options *diffopt)
  71{
  72        if (!diffopt || !diffopt->line_prefix)
  73                return;
  74
  75        fwrite(diffopt->line_prefix,
  76               sizeof(char),
  77               diffopt->line_prefix_length,
  78               diffopt->file);
  79}
  80
  81static const char **column_colors;
  82static unsigned short column_colors_max;
  83
  84static void parse_graph_colors_config(struct argv_array *colors, const char *string)
  85{
  86        const char *end, *start;
  87
  88        start = string;
  89        end = string + strlen(string);
  90        while (start < end) {
  91                const char *comma = strchrnul(start, ',');
  92                char color[COLOR_MAXLEN];
  93
  94                if (!color_parse_mem(start, comma - start, color))
  95                        argv_array_push(colors, color);
  96                else
  97                        warning(_("ignore invalid color '%.*s' in log.graphColors"),
  98                                (int)(comma - start), start);
  99                start = comma + 1;
 100        }
 101        argv_array_push(colors, GIT_COLOR_RESET);
 102}
 103
 104void graph_set_column_colors(const char **colors, unsigned short colors_max)
 105{
 106        column_colors = colors;
 107        column_colors_max = colors_max;
 108}
 109
 110static const char *column_get_color_code(unsigned short color)
 111{
 112        return column_colors[color];
 113}
 114
 115static void strbuf_write_column(struct strbuf *sb, const struct column *c,
 116                                char col_char)
 117{
 118        if (c->color < column_colors_max)
 119                strbuf_addstr(sb, column_get_color_code(c->color));
 120        strbuf_addch(sb, col_char);
 121        if (c->color < column_colors_max)
 122                strbuf_addstr(sb, column_get_color_code(column_colors_max));
 123}
 124
 125struct git_graph {
 126        /*
 127         * The commit currently being processed
 128         */
 129        struct commit *commit;
 130        /* The rev-info used for the current traversal */
 131        struct rev_info *revs;
 132        /*
 133         * The number of interesting parents that this commit has.
 134         *
 135         * Note that this is not the same as the actual number of parents.
 136         * This count excludes parents that won't be printed in the graph
 137         * output, as determined by graph_is_interesting().
 138         */
 139        int num_parents;
 140        /*
 141         * The width of the graph output for this commit.
 142         * All rows for this commit are padded to this width, so that
 143         * messages printed after the graph output are aligned.
 144         */
 145        int width;
 146        /*
 147         * The next expansion row to print
 148         * when state is GRAPH_PRE_COMMIT
 149         */
 150        int expansion_row;
 151        /*
 152         * The current output state.
 153         * This tells us what kind of line graph_next_line() should output.
 154         */
 155        enum graph_state state;
 156        /*
 157         * The output state for the previous line of output.
 158         * This is primarily used to determine how the first merge line
 159         * should appear, based on the last line of the previous commit.
 160         */
 161        enum graph_state prev_state;
 162        /*
 163         * The index of the column that refers to this commit.
 164         *
 165         * If none of the incoming columns refer to this commit,
 166         * this will be equal to num_columns.
 167         */
 168        int commit_index;
 169        /*
 170         * The commit_index for the previously displayed commit.
 171         *
 172         * This is used to determine how the first line of a merge
 173         * graph output should appear, based on the last line of the
 174         * previous commit.
 175         */
 176        int prev_commit_index;
 177        /*
 178         * The maximum number of columns that can be stored in the columns
 179         * and new_columns arrays.  This is also half the number of entries
 180         * that can be stored in the mapping and new_mapping arrays.
 181         */
 182        int column_capacity;
 183        /*
 184         * The number of columns (also called "branch lines" in some places)
 185         */
 186        int num_columns;
 187        /*
 188         * The number of columns in the new_columns array
 189         */
 190        int num_new_columns;
 191        /*
 192         * The number of entries in the mapping array
 193         */
 194        int mapping_size;
 195        /*
 196         * The column state before we output the current commit.
 197         */
 198        struct column *columns;
 199        /*
 200         * The new column state after we output the current commit.
 201         * Only valid when state is GRAPH_COLLAPSING.
 202         */
 203        struct column *new_columns;
 204        /*
 205         * An array that tracks the current state of each
 206         * character in the output line during state GRAPH_COLLAPSING.
 207         * Each entry is -1 if this character is empty, or a non-negative
 208         * integer if the character contains a branch line.  The value of
 209         * the integer indicates the target position for this branch line.
 210         * (I.e., this array maps the current column positions to their
 211         * desired positions.)
 212         *
 213         * The maximum capacity of this array is always
 214         * sizeof(int) * 2 * column_capacity.
 215         */
 216        int *mapping;
 217        /*
 218         * A temporary array for computing the next mapping state
 219         * while we are outputting a mapping line.  This is stored as part
 220         * of the git_graph simply so we don't have to allocate a new
 221         * temporary array each time we have to output a collapsing line.
 222         */
 223        int *new_mapping;
 224        /*
 225         * The current default column color being used.  This is
 226         * stored as an index into the array column_colors.
 227         */
 228        unsigned short default_column_color;
 229};
 230
 231static struct strbuf *diff_output_prefix_callback(struct diff_options *opt, void *data)
 232{
 233        struct git_graph *graph = data;
 234        static struct strbuf msgbuf = STRBUF_INIT;
 235
 236        assert(opt);
 237
 238        strbuf_reset(&msgbuf);
 239        if (opt->line_prefix)
 240                strbuf_add(&msgbuf, opt->line_prefix,
 241                           opt->line_prefix_length);
 242        if (graph)
 243                graph_padding_line(graph, &msgbuf);
 244        return &msgbuf;
 245}
 246
 247static const struct diff_options *default_diffopt;
 248
 249void graph_setup_line_prefix(struct diff_options *diffopt)
 250{
 251        default_diffopt = diffopt;
 252
 253        /* setup an output prefix callback if necessary */
 254        if (diffopt && !diffopt->output_prefix)
 255                diffopt->output_prefix = diff_output_prefix_callback;
 256}
 257
 258
 259struct git_graph *graph_init(struct rev_info *opt)
 260{
 261        struct git_graph *graph = xmalloc(sizeof(struct git_graph));
 262
 263        if (!column_colors) {
 264                char *string;
 265                if (git_config_get_string("log.graphcolors", &string)) {
 266                        /* not configured -- use default */
 267                        graph_set_column_colors(column_colors_ansi,
 268                                                column_colors_ansi_max);
 269                } else {
 270                        static struct argv_array custom_colors = ARGV_ARRAY_INIT;
 271                        argv_array_clear(&custom_colors);
 272                        parse_graph_colors_config(&custom_colors, string);
 273                        free(string);
 274                        /* graph_set_column_colors takes a max-index, not a count */
 275                        graph_set_column_colors(custom_colors.argv,
 276                                                custom_colors.argc - 1);
 277                }
 278        }
 279
 280        graph->commit = NULL;
 281        graph->revs = opt;
 282        graph->num_parents = 0;
 283        graph->expansion_row = 0;
 284        graph->state = GRAPH_PADDING;
 285        graph->prev_state = GRAPH_PADDING;
 286        graph->commit_index = 0;
 287        graph->prev_commit_index = 0;
 288        graph->num_columns = 0;
 289        graph->num_new_columns = 0;
 290        graph->mapping_size = 0;
 291        /*
 292         * Start the column color at the maximum value, since we'll
 293         * always increment it for the first commit we output.
 294         * This way we start at 0 for the first commit.
 295         */
 296        graph->default_column_color = column_colors_max - 1;
 297
 298        /*
 299         * Allocate a reasonably large default number of columns
 300         * We'll automatically grow columns later if we need more room.
 301         */
 302        graph->column_capacity = 30;
 303        ALLOC_ARRAY(graph->columns, graph->column_capacity);
 304        ALLOC_ARRAY(graph->new_columns, graph->column_capacity);
 305        ALLOC_ARRAY(graph->mapping, 2 * graph->column_capacity);
 306        ALLOC_ARRAY(graph->new_mapping, 2 * graph->column_capacity);
 307
 308        /*
 309         * The diff output prefix callback, with this we can make
 310         * all the diff output to align with the graph lines.
 311         */
 312        opt->diffopt.output_prefix = diff_output_prefix_callback;
 313        opt->diffopt.output_prefix_data = graph;
 314
 315        return graph;
 316}
 317
 318static void graph_update_state(struct git_graph *graph, enum graph_state s)
 319{
 320        graph->prev_state = graph->state;
 321        graph->state = s;
 322}
 323
 324static void graph_ensure_capacity(struct git_graph *graph, int num_columns)
 325{
 326        if (graph->column_capacity >= num_columns)
 327                return;
 328
 329        do {
 330                graph->column_capacity *= 2;
 331        } while (graph->column_capacity < num_columns);
 332
 333        REALLOC_ARRAY(graph->columns, graph->column_capacity);
 334        REALLOC_ARRAY(graph->new_columns, graph->column_capacity);
 335        REALLOC_ARRAY(graph->mapping, graph->column_capacity * 2);
 336        REALLOC_ARRAY(graph->new_mapping, graph->column_capacity * 2);
 337}
 338
 339/*
 340 * Returns 1 if the commit will be printed in the graph output,
 341 * and 0 otherwise.
 342 */
 343static int graph_is_interesting(struct git_graph *graph, struct commit *commit)
 344{
 345        /*
 346         * If revs->boundary is set, commits whose children have
 347         * been shown are always interesting, even if they have the
 348         * UNINTERESTING or TREESAME flags set.
 349         */
 350        if (graph->revs && graph->revs->boundary) {
 351                if (commit->object.flags & CHILD_SHOWN)
 352                        return 1;
 353        }
 354
 355        /*
 356         * Otherwise, use get_commit_action() to see if this commit is
 357         * interesting
 358         */
 359        return get_commit_action(graph->revs, commit) == commit_show;
 360}
 361
 362static struct commit_list *next_interesting_parent(struct git_graph *graph,
 363                                                   struct commit_list *orig)
 364{
 365        struct commit_list *list;
 366
 367        /*
 368         * If revs->first_parent_only is set, only the first
 369         * parent is interesting.  None of the others are.
 370         */
 371        if (graph->revs->first_parent_only)
 372                return NULL;
 373
 374        /*
 375         * Return the next interesting commit after orig
 376         */
 377        for (list = orig->next; list; list = list->next) {
 378                if (graph_is_interesting(graph, list->item))
 379                        return list;
 380        }
 381
 382        return NULL;
 383}
 384
 385static struct commit_list *first_interesting_parent(struct git_graph *graph)
 386{
 387        struct commit_list *parents = graph->commit->parents;
 388
 389        /*
 390         * If this commit has no parents, ignore it
 391         */
 392        if (!parents)
 393                return NULL;
 394
 395        /*
 396         * If the first parent is interesting, return it
 397         */
 398        if (graph_is_interesting(graph, parents->item))
 399                return parents;
 400
 401        /*
 402         * Otherwise, call next_interesting_parent() to get
 403         * the next interesting parent
 404         */
 405        return next_interesting_parent(graph, parents);
 406}
 407
 408static unsigned short graph_get_current_column_color(const struct git_graph *graph)
 409{
 410        if (!want_color(graph->revs->diffopt.use_color))
 411                return column_colors_max;
 412        return graph->default_column_color;
 413}
 414
 415/*
 416 * Update the graph's default column color.
 417 */
 418static void graph_increment_column_color(struct git_graph *graph)
 419{
 420        graph->default_column_color = (graph->default_column_color + 1) %
 421                column_colors_max;
 422}
 423
 424static unsigned short graph_find_commit_color(const struct git_graph *graph,
 425                                              const struct commit *commit)
 426{
 427        int i;
 428        for (i = 0; i < graph->num_columns; i++) {
 429                if (graph->columns[i].commit == commit)
 430                        return graph->columns[i].color;
 431        }
 432        return graph_get_current_column_color(graph);
 433}
 434
 435static void graph_insert_into_new_columns(struct git_graph *graph,
 436                                          struct commit *commit,
 437                                          int *mapping_index)
 438{
 439        int i;
 440
 441        /*
 442         * If the commit is already in the new_columns list, we don't need to
 443         * add it.  Just update the mapping correctly.
 444         */
 445        for (i = 0; i < graph->num_new_columns; i++) {
 446                if (graph->new_columns[i].commit == commit) {
 447                        graph->mapping[*mapping_index] = i;
 448                        *mapping_index += 2;
 449                        return;
 450                }
 451        }
 452
 453        /*
 454         * This commit isn't already in new_columns.  Add it.
 455         */
 456        graph->new_columns[graph->num_new_columns].commit = commit;
 457        graph->new_columns[graph->num_new_columns].color = graph_find_commit_color(graph, commit);
 458        graph->mapping[*mapping_index] = graph->num_new_columns;
 459        *mapping_index += 2;
 460        graph->num_new_columns++;
 461}
 462
 463static void graph_update_width(struct git_graph *graph,
 464                               int is_commit_in_existing_columns)
 465{
 466        /*
 467         * Compute the width needed to display the graph for this commit.
 468         * This is the maximum width needed for any row.  All other rows
 469         * will be padded to this width.
 470         *
 471         * Compute the number of columns in the widest row:
 472         * Count each existing column (graph->num_columns), and each new
 473         * column added by this commit.
 474         */
 475        int max_cols = graph->num_columns + graph->num_parents;
 476
 477        /*
 478         * Even if the current commit has no parents to be printed, it
 479         * still takes up a column for itself.
 480         */
 481        if (graph->num_parents < 1)
 482                max_cols++;
 483
 484        /*
 485         * We added a column for the current commit as part of
 486         * graph->num_parents.  If the current commit was already in
 487         * graph->columns, then we have double counted it.
 488         */
 489        if (is_commit_in_existing_columns)
 490                max_cols--;
 491
 492        /*
 493         * Each column takes up 2 spaces
 494         */
 495        graph->width = max_cols * 2;
 496}
 497
 498static void graph_update_columns(struct git_graph *graph)
 499{
 500        struct commit_list *parent;
 501        int max_new_columns;
 502        int mapping_idx;
 503        int i, seen_this, is_commit_in_columns;
 504
 505        /*
 506         * Swap graph->columns with graph->new_columns
 507         * graph->columns contains the state for the previous commit,
 508         * and new_columns now contains the state for our commit.
 509         *
 510         * We'll re-use the old columns array as storage to compute the new
 511         * columns list for the commit after this one.
 512         */
 513        SWAP(graph->columns, graph->new_columns);
 514        graph->num_columns = graph->num_new_columns;
 515        graph->num_new_columns = 0;
 516
 517        /*
 518         * Now update new_columns and mapping with the information for the
 519         * commit after this one.
 520         *
 521         * First, make sure we have enough room.  At most, there will
 522         * be graph->num_columns + graph->num_parents columns for the next
 523         * commit.
 524         */
 525        max_new_columns = graph->num_columns + graph->num_parents;
 526        graph_ensure_capacity(graph, max_new_columns);
 527
 528        /*
 529         * Clear out graph->mapping
 530         */
 531        graph->mapping_size = 2 * max_new_columns;
 532        for (i = 0; i < graph->mapping_size; i++)
 533                graph->mapping[i] = -1;
 534
 535        /*
 536         * Populate graph->new_columns and graph->mapping
 537         *
 538         * Some of the parents of this commit may already be in
 539         * graph->columns.  If so, graph->new_columns should only contain a
 540         * single entry for each such commit.  graph->mapping should
 541         * contain information about where each current branch line is
 542         * supposed to end up after the collapsing is performed.
 543         */
 544        seen_this = 0;
 545        mapping_idx = 0;
 546        is_commit_in_columns = 1;
 547        for (i = 0; i <= graph->num_columns; i++) {
 548                struct commit *col_commit;
 549                if (i == graph->num_columns) {
 550                        if (seen_this)
 551                                break;
 552                        is_commit_in_columns = 0;
 553                        col_commit = graph->commit;
 554                } else {
 555                        col_commit = graph->columns[i].commit;
 556                }
 557
 558                if (col_commit == graph->commit) {
 559                        int old_mapping_idx = mapping_idx;
 560                        seen_this = 1;
 561                        graph->commit_index = i;
 562                        for (parent = first_interesting_parent(graph);
 563                             parent;
 564                             parent = next_interesting_parent(graph, parent)) {
 565                                /*
 566                                 * If this is a merge, or the start of a new
 567                                 * childless column, increment the current
 568                                 * color.
 569                                 */
 570                                if (graph->num_parents > 1 ||
 571                                    !is_commit_in_columns) {
 572                                        graph_increment_column_color(graph);
 573                                }
 574                                graph_insert_into_new_columns(graph,
 575                                                              parent->item,
 576                                                              &mapping_idx);
 577                        }
 578                        /*
 579                         * We always need to increment mapping_idx by at
 580                         * least 2, even if it has no interesting parents.
 581                         * The current commit always takes up at least 2
 582                         * spaces.
 583                         */
 584                        if (mapping_idx == old_mapping_idx)
 585                                mapping_idx += 2;
 586                } else {
 587                        graph_insert_into_new_columns(graph, col_commit,
 588                                                      &mapping_idx);
 589                }
 590        }
 591
 592        /*
 593         * Shrink mapping_size to be the minimum necessary
 594         */
 595        while (graph->mapping_size > 1 &&
 596               graph->mapping[graph->mapping_size - 1] < 0)
 597                graph->mapping_size--;
 598
 599        /*
 600         * Compute graph->width for this commit
 601         */
 602        graph_update_width(graph, is_commit_in_columns);
 603}
 604
 605void graph_update(struct git_graph *graph, struct commit *commit)
 606{
 607        struct commit_list *parent;
 608
 609        /*
 610         * Set the new commit
 611         */
 612        graph->commit = commit;
 613
 614        /*
 615         * Count how many interesting parents this commit has
 616         */
 617        graph->num_parents = 0;
 618        for (parent = first_interesting_parent(graph);
 619             parent;
 620             parent = next_interesting_parent(graph, parent))
 621        {
 622                graph->num_parents++;
 623        }
 624
 625        /*
 626         * Store the old commit_index in prev_commit_index.
 627         * graph_update_columns() will update graph->commit_index for this
 628         * commit.
 629         */
 630        graph->prev_commit_index = graph->commit_index;
 631
 632        /*
 633         * Call graph_update_columns() to update
 634         * columns, new_columns, and mapping.
 635         */
 636        graph_update_columns(graph);
 637
 638        graph->expansion_row = 0;
 639
 640        /*
 641         * Update graph->state.
 642         * Note that we don't call graph_update_state() here, since
 643         * we don't want to update graph->prev_state.  No line for
 644         * graph->state was ever printed.
 645         *
 646         * If the previous commit didn't get to the GRAPH_PADDING state,
 647         * it never finished its output.  Goto GRAPH_SKIP, to print out
 648         * a line to indicate that portion of the graph is missing.
 649         *
 650         * If there are 3 or more parents, we may need to print extra rows
 651         * before the commit, to expand the branch lines around it and make
 652         * room for it.  We need to do this only if there is a branch row
 653         * (or more) to the right of this commit.
 654         *
 655         * If there are less than 3 parents, we can immediately print the
 656         * commit line.
 657         */
 658        if (graph->state != GRAPH_PADDING)
 659                graph->state = GRAPH_SKIP;
 660        else if (graph->num_parents >= 3 &&
 661                 graph->commit_index < (graph->num_columns - 1))
 662                graph->state = GRAPH_PRE_COMMIT;
 663        else
 664                graph->state = GRAPH_COMMIT;
 665}
 666
 667static int graph_is_mapping_correct(struct git_graph *graph)
 668{
 669        int i;
 670
 671        /*
 672         * The mapping is up to date if each entry is at its target,
 673         * or is 1 greater than its target.
 674         * (If it is 1 greater than the target, '/' will be printed, so it
 675         * will look correct on the next row.)
 676         */
 677        for (i = 0; i < graph->mapping_size; i++) {
 678                int target = graph->mapping[i];
 679                if (target < 0)
 680                        continue;
 681                if (target == (i / 2))
 682                        continue;
 683                return 0;
 684        }
 685
 686        return 1;
 687}
 688
 689static void graph_pad_horizontally(struct git_graph *graph, struct strbuf *sb,
 690                                   int chars_written)
 691{
 692        /*
 693         * Add additional spaces to the end of the strbuf, so that all
 694         * lines for a particular commit have the same width.
 695         *
 696         * This way, fields printed to the right of the graph will remain
 697         * aligned for the entire commit.
 698         */
 699        if (chars_written < graph->width)
 700                strbuf_addchars(sb, ' ', graph->width - chars_written);
 701}
 702
 703static void graph_output_padding_line(struct git_graph *graph,
 704                                      struct strbuf *sb)
 705{
 706        int i;
 707
 708        /*
 709         * We could conceivable be called with a NULL commit
 710         * if our caller has a bug, and invokes graph_next_line()
 711         * immediately after graph_init(), without first calling
 712         * graph_update().  Return without outputting anything in this
 713         * case.
 714         */
 715        if (!graph->commit)
 716                return;
 717
 718        /*
 719         * Output a padding row, that leaves all branch lines unchanged
 720         */
 721        for (i = 0; i < graph->num_new_columns; i++) {
 722                strbuf_write_column(sb, &graph->new_columns[i], '|');
 723                strbuf_addch(sb, ' ');
 724        }
 725
 726        graph_pad_horizontally(graph, sb, graph->num_new_columns * 2);
 727}
 728
 729
 730int graph_width(struct git_graph *graph)
 731{
 732        return graph->width;
 733}
 734
 735
 736static void graph_output_skip_line(struct git_graph *graph, struct strbuf *sb)
 737{
 738        /*
 739         * Output an ellipsis to indicate that a portion
 740         * of the graph is missing.
 741         */
 742        strbuf_addstr(sb, "...");
 743        graph_pad_horizontally(graph, sb, 3);
 744
 745        if (graph->num_parents >= 3 &&
 746            graph->commit_index < (graph->num_columns - 1))
 747                graph_update_state(graph, GRAPH_PRE_COMMIT);
 748        else
 749                graph_update_state(graph, GRAPH_COMMIT);
 750}
 751
 752static void graph_output_pre_commit_line(struct git_graph *graph,
 753                                         struct strbuf *sb)
 754{
 755        int num_expansion_rows;
 756        int i, seen_this;
 757        int chars_written;
 758
 759        /*
 760         * This function formats a row that increases the space around a commit
 761         * with multiple parents, to make room for it.  It should only be
 762         * called when there are 3 or more parents.
 763         *
 764         * We need 2 extra rows for every parent over 2.
 765         */
 766        assert(graph->num_parents >= 3);
 767        num_expansion_rows = (graph->num_parents - 2) * 2;
 768
 769        /*
 770         * graph->expansion_row tracks the current expansion row we are on.
 771         * It should be in the range [0, num_expansion_rows - 1]
 772         */
 773        assert(0 <= graph->expansion_row &&
 774               graph->expansion_row < num_expansion_rows);
 775
 776        /*
 777         * Output the row
 778         */
 779        seen_this = 0;
 780        chars_written = 0;
 781        for (i = 0; i < graph->num_columns; i++) {
 782                struct column *col = &graph->columns[i];
 783                if (col->commit == graph->commit) {
 784                        seen_this = 1;
 785                        strbuf_write_column(sb, col, '|');
 786                        strbuf_addchars(sb, ' ', graph->expansion_row);
 787                        chars_written += 1 + graph->expansion_row;
 788                } else if (seen_this && (graph->expansion_row == 0)) {
 789                        /*
 790                         * This is the first line of the pre-commit output.
 791                         * If the previous commit was a merge commit and
 792                         * ended in the GRAPH_POST_MERGE state, all branch
 793                         * lines after graph->prev_commit_index were
 794                         * printed as "\" on the previous line.  Continue
 795                         * to print them as "\" on this line.  Otherwise,
 796                         * print the branch lines as "|".
 797                         */
 798                        if (graph->prev_state == GRAPH_POST_MERGE &&
 799                            graph->prev_commit_index < i)
 800                                strbuf_write_column(sb, col, '\\');
 801                        else
 802                                strbuf_write_column(sb, col, '|');
 803                        chars_written++;
 804                } else if (seen_this && (graph->expansion_row > 0)) {
 805                        strbuf_write_column(sb, col, '\\');
 806                        chars_written++;
 807                } else {
 808                        strbuf_write_column(sb, col, '|');
 809                        chars_written++;
 810                }
 811                strbuf_addch(sb, ' ');
 812                chars_written++;
 813        }
 814
 815        graph_pad_horizontally(graph, sb, chars_written);
 816
 817        /*
 818         * Increment graph->expansion_row,
 819         * and move to state GRAPH_COMMIT if necessary
 820         */
 821        graph->expansion_row++;
 822        if (graph->expansion_row >= num_expansion_rows)
 823                graph_update_state(graph, GRAPH_COMMIT);
 824}
 825
 826static void graph_output_commit_char(struct git_graph *graph, struct strbuf *sb)
 827{
 828        /*
 829         * For boundary commits, print 'o'
 830         * (We should only see boundary commits when revs->boundary is set.)
 831         */
 832        if (graph->commit->object.flags & BOUNDARY) {
 833                assert(graph->revs->boundary);
 834                strbuf_addch(sb, 'o');
 835                return;
 836        }
 837
 838        /*
 839         * get_revision_mark() handles all other cases without assert()
 840         */
 841        strbuf_addstr(sb, get_revision_mark(graph->revs, graph->commit));
 842}
 843
 844/*
 845 * Draw an octopus merge and return the number of characters written.
 846 */
 847static int graph_draw_octopus_merge(struct git_graph *graph,
 848                                    struct strbuf *sb)
 849{
 850        /*
 851         * Here dashless_commits represents the number of parents
 852         * which don't need to have dashes (because their edges fit
 853         * neatly under the commit).
 854         */
 855        const int dashless_commits = 2;
 856        int col_num, i;
 857        int num_dashes =
 858                ((graph->num_parents - dashless_commits) * 2) - 1;
 859        for (i = 0; i < num_dashes; i++) {
 860                col_num = (i / 2) + dashless_commits + graph->commit_index;
 861                strbuf_write_column(sb, &graph->new_columns[col_num], '-');
 862        }
 863        col_num = (i / 2) + dashless_commits + graph->commit_index;
 864        strbuf_write_column(sb, &graph->new_columns[col_num], '.');
 865        return num_dashes + 1;
 866}
 867
 868static void graph_output_commit_line(struct git_graph *graph, struct strbuf *sb)
 869{
 870        int seen_this = 0;
 871        int i, chars_written;
 872
 873        /*
 874         * Output the row containing this commit
 875         * Iterate up to and including graph->num_columns,
 876         * since the current commit may not be in any of the existing
 877         * columns.  (This happens when the current commit doesn't have any
 878         * children that we have already processed.)
 879         */
 880        seen_this = 0;
 881        chars_written = 0;
 882        for (i = 0; i <= graph->num_columns; i++) {
 883                struct column *col = &graph->columns[i];
 884                struct commit *col_commit;
 885                if (i == graph->num_columns) {
 886                        if (seen_this)
 887                                break;
 888                        col_commit = graph->commit;
 889                } else {
 890                        col_commit = graph->columns[i].commit;
 891                }
 892
 893                if (col_commit == graph->commit) {
 894                        seen_this = 1;
 895                        graph_output_commit_char(graph, sb);
 896                        chars_written++;
 897
 898                        if (graph->num_parents > 2)
 899                                chars_written += graph_draw_octopus_merge(graph,
 900                                                                          sb);
 901                } else if (seen_this && (graph->num_parents > 2)) {
 902                        strbuf_write_column(sb, col, '\\');
 903                        chars_written++;
 904                } else if (seen_this && (graph->num_parents == 2)) {
 905                        /*
 906                         * This is a 2-way merge commit.
 907                         * There is no GRAPH_PRE_COMMIT stage for 2-way
 908                         * merges, so this is the first line of output
 909                         * for this commit.  Check to see what the previous
 910                         * line of output was.
 911                         *
 912                         * If it was GRAPH_POST_MERGE, the branch line
 913                         * coming into this commit may have been '\',
 914                         * and not '|' or '/'.  If so, output the branch
 915                         * line as '\' on this line, instead of '|'.  This
 916                         * makes the output look nicer.
 917                         */
 918                        if (graph->prev_state == GRAPH_POST_MERGE &&
 919                            graph->prev_commit_index < i)
 920                                strbuf_write_column(sb, col, '\\');
 921                        else
 922                                strbuf_write_column(sb, col, '|');
 923                        chars_written++;
 924                } else {
 925                        strbuf_write_column(sb, col, '|');
 926                        chars_written++;
 927                }
 928                strbuf_addch(sb, ' ');
 929                chars_written++;
 930        }
 931
 932        graph_pad_horizontally(graph, sb, chars_written);
 933
 934        /*
 935         * Update graph->state
 936         */
 937        if (graph->num_parents > 1)
 938                graph_update_state(graph, GRAPH_POST_MERGE);
 939        else if (graph_is_mapping_correct(graph))
 940                graph_update_state(graph, GRAPH_PADDING);
 941        else
 942                graph_update_state(graph, GRAPH_COLLAPSING);
 943}
 944
 945static struct column *find_new_column_by_commit(struct git_graph *graph,
 946                                                struct commit *commit)
 947{
 948        int i;
 949        for (i = 0; i < graph->num_new_columns; i++) {
 950                if (graph->new_columns[i].commit == commit)
 951                        return &graph->new_columns[i];
 952        }
 953        return NULL;
 954}
 955
 956static void graph_output_post_merge_line(struct git_graph *graph, struct strbuf *sb)
 957{
 958        int seen_this = 0;
 959        int i, j, chars_written;
 960
 961        /*
 962         * Output the post-merge row
 963         */
 964        chars_written = 0;
 965        for (i = 0; i <= graph->num_columns; i++) {
 966                struct column *col = &graph->columns[i];
 967                struct commit *col_commit;
 968                if (i == graph->num_columns) {
 969                        if (seen_this)
 970                                break;
 971                        col_commit = graph->commit;
 972                } else {
 973                        col_commit = col->commit;
 974                }
 975
 976                if (col_commit == graph->commit) {
 977                        /*
 978                         * Since the current commit is a merge find
 979                         * the columns for the parent commits in
 980                         * new_columns and use those to format the
 981                         * edges.
 982                         */
 983                        struct commit_list *parents = NULL;
 984                        struct column *par_column;
 985                        seen_this = 1;
 986                        parents = first_interesting_parent(graph);
 987                        assert(parents);
 988                        par_column = find_new_column_by_commit(graph, parents->item);
 989                        assert(par_column);
 990
 991                        strbuf_write_column(sb, par_column, '|');
 992                        chars_written++;
 993                        for (j = 0; j < graph->num_parents - 1; j++) {
 994                                parents = next_interesting_parent(graph, parents);
 995                                assert(parents);
 996                                par_column = find_new_column_by_commit(graph, parents->item);
 997                                assert(par_column);
 998                                strbuf_write_column(sb, par_column, '\\');
 999                                strbuf_addch(sb, ' ');
1000                        }
1001                        chars_written += j * 2;
1002                } else if (seen_this) {
1003                        strbuf_write_column(sb, col, '\\');
1004                        strbuf_addch(sb, ' ');
1005                        chars_written += 2;
1006                } else {
1007                        strbuf_write_column(sb, col, '|');
1008                        strbuf_addch(sb, ' ');
1009                        chars_written += 2;
1010                }
1011        }
1012
1013        graph_pad_horizontally(graph, sb, chars_written);
1014
1015        /*
1016         * Update graph->state
1017         */
1018        if (graph_is_mapping_correct(graph))
1019                graph_update_state(graph, GRAPH_PADDING);
1020        else
1021                graph_update_state(graph, GRAPH_COLLAPSING);
1022}
1023
1024static void graph_output_collapsing_line(struct git_graph *graph, struct strbuf *sb)
1025{
1026        int i;
1027        short used_horizontal = 0;
1028        int horizontal_edge = -1;
1029        int horizontal_edge_target = -1;
1030
1031        /*
1032         * Clear out the new_mapping array
1033         */
1034        for (i = 0; i < graph->mapping_size; i++)
1035                graph->new_mapping[i] = -1;
1036
1037        for (i = 0; i < graph->mapping_size; i++) {
1038                int target = graph->mapping[i];
1039                if (target < 0)
1040                        continue;
1041
1042                /*
1043                 * Since update_columns() always inserts the leftmost
1044                 * column first, each branch's target location should
1045                 * always be either its current location or to the left of
1046                 * its current location.
1047                 *
1048                 * We never have to move branches to the right.  This makes
1049                 * the graph much more legible, since whenever branches
1050                 * cross, only one is moving directions.
1051                 */
1052                assert(target * 2 <= i);
1053
1054                if (target * 2 == i) {
1055                        /*
1056                         * This column is already in the
1057                         * correct place
1058                         */
1059                        assert(graph->new_mapping[i] == -1);
1060                        graph->new_mapping[i] = target;
1061                } else if (graph->new_mapping[i - 1] < 0) {
1062                        /*
1063                         * Nothing is to the left.
1064                         * Move to the left by one
1065                         */
1066                        graph->new_mapping[i - 1] = target;
1067                        /*
1068                         * If there isn't already an edge moving horizontally
1069                         * select this one.
1070                         */
1071                        if (horizontal_edge == -1) {
1072                                int j;
1073                                horizontal_edge = i;
1074                                horizontal_edge_target = target;
1075                                /*
1076                                 * The variable target is the index of the graph
1077                                 * column, and therefore target*2+3 is the
1078                                 * actual screen column of the first horizontal
1079                                 * line.
1080                                 */
1081                                for (j = (target * 2)+3; j < (i - 2); j += 2)
1082                                        graph->new_mapping[j] = target;
1083                        }
1084                } else if (graph->new_mapping[i - 1] == target) {
1085                        /*
1086                         * There is a branch line to our left
1087                         * already, and it is our target.  We
1088                         * combine with this line, since we share
1089                         * the same parent commit.
1090                         *
1091                         * We don't have to add anything to the
1092                         * output or new_mapping, since the
1093                         * existing branch line has already taken
1094                         * care of it.
1095                         */
1096                } else {
1097                        /*
1098                         * There is a branch line to our left,
1099                         * but it isn't our target.  We need to
1100                         * cross over it.
1101                         *
1102                         * The space just to the left of this
1103                         * branch should always be empty.
1104                         *
1105                         * The branch to the left of that space
1106                         * should be our eventual target.
1107                         */
1108                        assert(graph->new_mapping[i - 1] > target);
1109                        assert(graph->new_mapping[i - 2] < 0);
1110                        assert(graph->new_mapping[i - 3] == target);
1111                        graph->new_mapping[i - 2] = target;
1112                        /*
1113                         * Mark this branch as the horizontal edge to
1114                         * prevent any other edges from moving
1115                         * horizontally.
1116                         */
1117                        if (horizontal_edge == -1)
1118                                horizontal_edge = i;
1119                }
1120        }
1121
1122        /*
1123         * The new mapping may be 1 smaller than the old mapping
1124         */
1125        if (graph->new_mapping[graph->mapping_size - 1] < 0)
1126                graph->mapping_size--;
1127
1128        /*
1129         * Output out a line based on the new mapping info
1130         */
1131        for (i = 0; i < graph->mapping_size; i++) {
1132                int target = graph->new_mapping[i];
1133                if (target < 0)
1134                        strbuf_addch(sb, ' ');
1135                else if (target * 2 == i)
1136                        strbuf_write_column(sb, &graph->new_columns[target], '|');
1137                else if (target == horizontal_edge_target &&
1138                         i != horizontal_edge - 1) {
1139                                /*
1140                                 * Set the mappings for all but the
1141                                 * first segment to -1 so that they
1142                                 * won't continue into the next line.
1143                                 */
1144                                if (i != (target * 2)+3)
1145                                        graph->new_mapping[i] = -1;
1146                                used_horizontal = 1;
1147                        strbuf_write_column(sb, &graph->new_columns[target], '_');
1148                } else {
1149                        if (used_horizontal && i < horizontal_edge)
1150                                graph->new_mapping[i] = -1;
1151                        strbuf_write_column(sb, &graph->new_columns[target], '/');
1152
1153                }
1154        }
1155
1156        graph_pad_horizontally(graph, sb, graph->mapping_size);
1157
1158        /*
1159         * Swap mapping and new_mapping
1160         */
1161        SWAP(graph->mapping, graph->new_mapping);
1162
1163        /*
1164         * If graph->mapping indicates that all of the branch lines
1165         * are already in the correct positions, we are done.
1166         * Otherwise, we need to collapse some branch lines together.
1167         */
1168        if (graph_is_mapping_correct(graph))
1169                graph_update_state(graph, GRAPH_PADDING);
1170}
1171
1172int graph_next_line(struct git_graph *graph, struct strbuf *sb)
1173{
1174        switch (graph->state) {
1175        case GRAPH_PADDING:
1176                graph_output_padding_line(graph, sb);
1177                return 0;
1178        case GRAPH_SKIP:
1179                graph_output_skip_line(graph, sb);
1180                return 0;
1181        case GRAPH_PRE_COMMIT:
1182                graph_output_pre_commit_line(graph, sb);
1183                return 0;
1184        case GRAPH_COMMIT:
1185                graph_output_commit_line(graph, sb);
1186                return 1;
1187        case GRAPH_POST_MERGE:
1188                graph_output_post_merge_line(graph, sb);
1189                return 0;
1190        case GRAPH_COLLAPSING:
1191                graph_output_collapsing_line(graph, sb);
1192                return 0;
1193        }
1194
1195        assert(0);
1196        return 0;
1197}
1198
1199static void graph_padding_line(struct git_graph *graph, struct strbuf *sb)
1200{
1201        int i;
1202        int chars_written = 0;
1203
1204        if (graph->state != GRAPH_COMMIT) {
1205                graph_next_line(graph, sb);
1206                return;
1207        }
1208
1209        /*
1210         * Output the row containing this commit
1211         * Iterate up to and including graph->num_columns,
1212         * since the current commit may not be in any of the existing
1213         * columns.  (This happens when the current commit doesn't have any
1214         * children that we have already processed.)
1215         */
1216        for (i = 0; i < graph->num_columns; i++) {
1217                struct column *col = &graph->columns[i];
1218
1219                strbuf_write_column(sb, col, '|');
1220                chars_written++;
1221
1222                if (col->commit == graph->commit && graph->num_parents > 2) {
1223                        int len = (graph->num_parents - 2) * 2;
1224                        strbuf_addchars(sb, ' ', len);
1225                        chars_written += len;
1226                } else {
1227                        strbuf_addch(sb, ' ');
1228                        chars_written++;
1229                }
1230        }
1231
1232        graph_pad_horizontally(graph, sb, chars_written);
1233
1234        /*
1235         * Update graph->prev_state since we have output a padding line
1236         */
1237        graph->prev_state = GRAPH_PADDING;
1238}
1239
1240int graph_is_commit_finished(struct git_graph const *graph)
1241{
1242        return (graph->state == GRAPH_PADDING);
1243}
1244
1245void graph_show_commit(struct git_graph *graph)
1246{
1247        struct strbuf msgbuf = STRBUF_INIT;
1248        int shown_commit_line = 0;
1249
1250        graph_show_line_prefix(default_diffopt);
1251
1252        if (!graph)
1253                return;
1254
1255        /*
1256         * When showing a diff of a merge against each of its parents, we
1257         * are called once for each parent without graph_update having been
1258         * called.  In this case, simply output a single padding line.
1259         */
1260        if (graph_is_commit_finished(graph)) {
1261                graph_show_padding(graph);
1262                shown_commit_line = 1;
1263        }
1264
1265        while (!shown_commit_line && !graph_is_commit_finished(graph)) {
1266                shown_commit_line = graph_next_line(graph, &msgbuf);
1267                fwrite(msgbuf.buf, sizeof(char), msgbuf.len,
1268                        graph->revs->diffopt.file);
1269                if (!shown_commit_line) {
1270                        putc('\n', graph->revs->diffopt.file);
1271                        graph_show_line_prefix(&graph->revs->diffopt);
1272                }
1273                strbuf_setlen(&msgbuf, 0);
1274        }
1275
1276        strbuf_release(&msgbuf);
1277}
1278
1279void graph_show_oneline(struct git_graph *graph)
1280{
1281        struct strbuf msgbuf = STRBUF_INIT;
1282
1283        graph_show_line_prefix(default_diffopt);
1284
1285        if (!graph)
1286                return;
1287
1288        graph_next_line(graph, &msgbuf);
1289        fwrite(msgbuf.buf, sizeof(char), msgbuf.len, graph->revs->diffopt.file);
1290        strbuf_release(&msgbuf);
1291}
1292
1293void graph_show_padding(struct git_graph *graph)
1294{
1295        struct strbuf msgbuf = STRBUF_INIT;
1296
1297        graph_show_line_prefix(default_diffopt);
1298
1299        if (!graph)
1300                return;
1301
1302        graph_padding_line(graph, &msgbuf);
1303        fwrite(msgbuf.buf, sizeof(char), msgbuf.len, graph->revs->diffopt.file);
1304        strbuf_release(&msgbuf);
1305}
1306
1307int graph_show_remainder(struct git_graph *graph)
1308{
1309        struct strbuf msgbuf = STRBUF_INIT;
1310        int shown = 0;
1311
1312        graph_show_line_prefix(default_diffopt);
1313
1314        if (!graph)
1315                return 0;
1316
1317        if (graph_is_commit_finished(graph))
1318                return 0;
1319
1320        for (;;) {
1321                graph_next_line(graph, &msgbuf);
1322                fwrite(msgbuf.buf, sizeof(char), msgbuf.len,
1323                        graph->revs->diffopt.file);
1324                strbuf_setlen(&msgbuf, 0);
1325                shown = 1;
1326
1327                if (!graph_is_commit_finished(graph)) {
1328                        putc('\n', graph->revs->diffopt.file);
1329                        graph_show_line_prefix(&graph->revs->diffopt);
1330                } else {
1331                        break;
1332                }
1333        }
1334        strbuf_release(&msgbuf);
1335
1336        return shown;
1337}
1338
1339static void graph_show_strbuf(struct git_graph *graph,
1340                              FILE *file,
1341                              struct strbuf const *sb)
1342{
1343        char *p;
1344
1345        /*
1346         * Print the strbuf line by line,
1347         * and display the graph info before each line but the first.
1348         */
1349        p = sb->buf;
1350        while (p) {
1351                size_t len;
1352                char *next_p = strchr(p, '\n');
1353                if (next_p) {
1354                        next_p++;
1355                        len = next_p - p;
1356                } else {
1357                        len = (sb->buf + sb->len) - p;
1358                }
1359                fwrite(p, sizeof(char), len, file);
1360                if (next_p && *next_p != '\0')
1361                        graph_show_oneline(graph);
1362                p = next_p;
1363        }
1364}
1365
1366void graph_show_commit_msg(struct git_graph *graph,
1367                           FILE *file,
1368                           struct strbuf const *sb)
1369{
1370        int newline_terminated;
1371
1372        /*
1373         * Show the commit message
1374         */
1375        graph_show_strbuf(graph, file, sb);
1376
1377        if (!graph)
1378                return;
1379
1380        newline_terminated = (sb->len && sb->buf[sb->len - 1] == '\n');
1381
1382        /*
1383         * If there is more output needed for this commit, show it now
1384         */
1385        if (!graph_is_commit_finished(graph)) {
1386                /*
1387                 * If sb doesn't have a terminating newline, print one now,
1388                 * so we can start the remainder of the graph output on a
1389                 * new line.
1390                 */
1391                if (!newline_terminated)
1392                        putc('\n', file);
1393
1394                graph_show_remainder(graph);
1395
1396                /*
1397                 * If sb ends with a newline, our output should too.
1398                 */
1399                if (newline_terminated)
1400                        putc('\n', file);
1401        }
1402}