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

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "graph.h"
   4 #include "diff.h"
   5 #include "revision.h"
   6
   7 /*
   8  * TODO:
   9  * - Add colors to the graph.
  10  *   Pick a color for each column, and print all characters
  11  *   in that column with the specified color.
  12  *
  13  * - Limit the number of columns, similar to the way gitk does.
  14  *   If we reach more than a specified number of columns, omit
  15  *   sections of some columns.
  16  *
  17  * - The output during the GRAPH_PRE_COMMIT and GRAPH_COLLAPSING states
  18  *   could be made more compact by printing horizontal lines, instead of
  19  *   long diagonal lines.  For example, during collapsing, something like
  20  *   this:          instead of this:
  21  *   | | | | |      | | | | |
  22  *   | |_|_|/       | | | |/
  23  *   |/| | |        | | |/|
  24  *   | | | |        | |/| |
  25  *                  |/| | |
  26  *                  | | | |
  27  *
  28  *   If there are several parallel diagonal lines, they will need to be
  29  *   replaced with horizontal lines on subsequent rows.
  30  */
  31
  32 struct column {
  33         /*
  34          * The parent commit of this column.
  35          */
  36         struct commit *commit;
  37         /*
  38          * XXX: Once we add support for colors, struct column could also
  39          * contain the color of its branch line.
  40          */
  41 };
  42
  43 enum graph_state {
  44         GRAPH_PADDING,
  45         GRAPH_SKIP,
  46         GRAPH_PRE_COMMIT,
  47         GRAPH_COMMIT,
  48         GRAPH_POST_MERGE,
  49         GRAPH_COLLAPSING
  50 };
  51
  52 struct git_graph {
  53         /*
  54          * The commit currently being processed
  55          */
  56         struct commit *commit;
  57         /* The rev-info used for the current traversal */
  58         struct rev_info *revs;
  59         /*
  60          * The number of interesting parents that this commit has.
  61          *
  62          * Note that this is not the same as the actual number of parents.
  63          * This count excludes parents that won't be printed in the graph
  64          * output, as determined by graph_is_interesting().
  65          */
  66         int num_parents;
  67         /*
  68          * The width of the graph output for this commit.
  69          * All rows for this commit are padded to this width, so that
  70          * messages printed after the graph output are aligned.
  71          */
  72         int width;
  73         /*
  74          * The next expansion row to print
  75          * when state is GRAPH_PRE_COMMIT
  76          */
  77         int expansion_row;
  78         /*
  79          * The current output state.
  80          * This tells us what kind of line graph_next_line() should output.
  81          */
  82         enum graph_state state;
  83         /*
  84          * The output state for the previous line of output.
  85          * This is primarily used to determine how the first merge line
  86          * should appear, based on the last line of the previous commit.
  87          */
  88         enum graph_state prev_state;
  89         /*
  90          * The index of the column that refers to this commit.
  91          *
  92          * If none of the incoming columns refer to this commit,
  93          * this will be equal to num_columns.
  94          */
  95         int commit_index;
  96         /*
  97          * The commit_index for the previously displayed commit.
  98          *
  99          * This is used to determine how the first line of a merge
 100          * graph output should appear, based on the last line of the
 101          * previous commit.
 102          */
 103         int prev_commit_index;
 104         /*
 105          * The maximum number of columns that can be stored in the columns
 106          * and new_columns arrays.  This is also half the number of entries
 107          * that can be stored in the mapping and new_mapping arrays.
 108          */
 109         int column_capacity;
 110         /*
 111          * The number of columns (also called "branch lines" in some places)
 112          */
 113         int num_columns;
 114         /*
 115          * The number of columns in the new_columns array
 116          */
 117         int num_new_columns;
 118         /*
 119          * The number of entries in the mapping array
 120          */
 121         int mapping_size;
 122         /*
 123          * The column state before we output the current commit.
 124          */
 125         struct column *columns;
 126         /*
 127          * The new column state after we output the current commit.
 128          * Only valid when state is GRAPH_COLLAPSING.
 129          */
 130         struct column *new_columns;
 131         /*
 132          * An array that tracks the current state of each
 133          * character in the output line during state GRAPH_COLLAPSING.
 134          * Each entry is -1 if this character is empty, or a non-negative
 135          * integer if the character contains a branch line.  The value of
 136          * the integer indicates the target position for this branch line.
 137          * (I.e., this array maps the current column positions to their
 138          * desired positions.)
 139          *
 140          * The maximum capacity of this array is always
 141          * sizeof(int) * 2 * column_capacity.
 142          */
 143         int *mapping;
 144         /*
 145          * A temporary array for computing the next mapping state
 146          * while we are outputting a mapping line.  This is stored as part
 147          * of the git_graph simply so we don't have to allocate a new
 148          * temporary array each time we have to output a collapsing line.
 149          */
 150         int *new_mapping;
 151 };
 152
 153 struct git_graph *graph_init(struct rev_info *opt)
 154 {
 155         struct git_graph *graph = xmalloc(sizeof(struct git_graph));
 156         graph->commit = NULL;
 157         graph->revs = opt;
 158         graph->num_parents = 0;
 159         graph->expansion_row = 0;
 160         graph->state = GRAPH_PADDING;
 161         graph->prev_state = GRAPH_PADDING;
 162         graph->commit_index = 0;
 163         graph->prev_commit_index = 0;
 164         graph->num_columns = 0;
 165         graph->num_new_columns = 0;
 166         graph->mapping_size = 0;
 167
 168         /*
 169          * Allocate a reasonably large default number of columns
 170          * We'll automatically grow columns later if we need more room.
 171          */
 172         graph->column_capacity = 30;
 173         graph->columns = xmalloc(sizeof(struct column) *
 174                                  graph->column_capacity);
 175         graph->new_columns = xmalloc(sizeof(struct column) *
 176                                      graph->column_capacity);
 177         graph->mapping = xmalloc(sizeof(int) * 2 * graph->column_capacity);
 178         graph->new_mapping = xmalloc(sizeof(int) * 2 * graph->column_capacity);
 179
 180         return graph;
 181 }
 182
 183 void graph_release(struct git_graph *graph)
 184 {
 185         free(graph->columns);
 186         free(graph->new_columns);
 187         free(graph->mapping);
 188         free(graph);
 189 }
 190
 191 static void graph_update_state(struct git_graph *graph, enum graph_state s)
 192 {
 193         graph->prev_state = graph->state;
 194         graph->state = s;
 195 }
 196
 197 static void graph_ensure_capacity(struct git_graph *graph, int num_columns)
 198 {
 199         if (graph->column_capacity >= num_columns)
 200                 return;
 201
 202         do {
 203                 graph->column_capacity *= 2;
 204         } while (graph->column_capacity < num_columns);
 205
 206         graph->columns = xrealloc(graph->columns,
 207                                   sizeof(struct column) *
 208                                   graph->column_capacity);
 209         graph->new_columns = xrealloc(graph->new_columns,
 210                                       sizeof(struct column) *
 211                                       graph->column_capacity);
 212         graph->mapping = xrealloc(graph->mapping,
 213                                   sizeof(int) * 2 * graph->column_capacity);
 214         graph->new_mapping = xrealloc(graph->new_mapping,
 215                                       sizeof(int) * 2 * graph->column_capacity);
 216 }
 217
 218 /*
 219  * Returns 1 if the commit will be printed in the graph output,
 220  * and 0 otherwise.
 221  */
 222 static int graph_is_interesting(struct git_graph *graph, struct commit *commit)
 223 {
 224         /*
 225          * If revs->boundary is set, commits whose children have
 226          * been shown are always interesting, even if they have the
 227          * UNINTERESTING or TREESAME flags set.
 228          */
 229         if (graph->revs && graph->revs->boundary) {
 230                 if (commit->object.flags & CHILD_SHOWN)
 231                         return 1;
 232         }
 233
 234         /*
 235          * Uninteresting and pruned commits won't be printed
 236          */
 237         return (commit->object.flags & (UNINTERESTING | TREESAME)) ? 0 : 1;
 238 }
 239
 240 static void graph_insert_into_new_columns(struct git_graph *graph,
 241                                           struct commit *commit,
 242                                           int *mapping_index)
 243 {
 244         int i;
 245
 246         /*
 247          * Ignore uinteresting commits
 248          */
 249         if (!graph_is_interesting(graph, commit))
 250                 return;
 251
 252         /*
 253          * If the commit is already in the new_columns list, we don't need to
 254          * add it.  Just update the mapping correctly.
 255          */
 256         for (i = 0; i < graph->num_new_columns; i++) {
 257                 if (graph->new_columns[i].commit == commit) {
 258                         graph->mapping[*mapping_index] = i;
 259                         *mapping_index += 2;
 260                         return;
 261                 }
 262         }
 263
 264         /*
 265          * This commit isn't already in new_columns.  Add it.
 266          */
 267         graph->new_columns[graph->num_new_columns].commit = commit;
 268         graph->mapping[*mapping_index] = graph->num_new_columns;
 269         *mapping_index += 2;
 270         graph->num_new_columns++;
 271 }
 272
 273 static void graph_update_width(struct git_graph *graph,
 274                                int is_commit_in_existing_columns)
 275 {
 276         /*
 277          * Compute the width needed to display the graph for this commit.
 278          * This is the maximum width needed for any row.  All other rows
 279          * will be padded to this width.
 280          *
 281          * Compute the number of columns in the widest row:
 282          * Count each existing column (graph->num_columns), and each new
 283          * column added by this commit.
 284          */
 285         int max_cols = graph->num_columns + graph->num_parents;
 286
 287         /*
 288          * Even if the current commit has no parents to be printed, it
 289          * still takes up a column for itself.
 290          */
 291         if (graph->num_parents < 1)
 292                 max_cols++;
 293
 294         /*
 295          * We added a column for the the current commit as part of
 296          * graph->num_parents.  If the current commit was already in
 297          * graph->columns, then we have double counted it.
 298          */
 299         if (is_commit_in_existing_columns)
 300                 max_cols--;
 301
 302         /*
 303          * Each column takes up 2 spaces
 304          */
 305         graph->width = max_cols * 2;
 306 }
 307
 308 static void graph_update_columns(struct git_graph *graph)
 309 {
 310         struct commit_list *parent;
 311         struct column *tmp_columns;
 312         int max_new_columns;
 313         int mapping_idx;
 314         int i, seen_this, is_commit_in_columns;
 315
 316         /*
 317          * Swap graph->columns with graph->new_columns
 318          * graph->columns contains the state for the previous commit,
 319          * and new_columns now contains the state for our commit.
 320          *
 321          * We'll re-use the old columns array as storage to compute the new
 322          * columns list for the commit after this one.
 323          */
 324         tmp_columns = graph->columns;
 325         graph->columns = graph->new_columns;
 326         graph->num_columns = graph->num_new_columns;
 327
 328         graph->new_columns = tmp_columns;
 329         graph->num_new_columns = 0;
 330
 331         /*
 332          * Now update new_columns and mapping with the information for the
 333          * commit after this one.
 334          *
 335          * First, make sure we have enough room.  At most, there will
 336          * be graph->num_columns + graph->num_parents columns for the next
 337          * commit.
 338          */
 339         max_new_columns = graph->num_columns + graph->num_parents;
 340         graph_ensure_capacity(graph, max_new_columns);
 341
 342         /*
 343          * Clear out graph->mapping
 344          */
 345         graph->mapping_size = 2 * max_new_columns;
 346         for (i = 0; i < graph->mapping_size; i++)
 347                 graph->mapping[i] = -1;
 348
 349         /*
 350          * Populate graph->new_columns and graph->mapping
 351          *
 352          * Some of the parents of this commit may already be in
 353          * graph->columns.  If so, graph->new_columns should only contain a
 354          * single entry for each such commit.  graph->mapping should
 355          * contain information about where each current branch line is
 356          * supposed to end up after the collapsing is performed.
 357          */
 358         seen_this = 0;
 359         mapping_idx = 0;
 360         is_commit_in_columns = 1;
 361         for (i = 0; i <= graph->num_columns; i++) {
 362                 struct commit *col_commit;
 363                 if (i == graph->num_columns) {
 364                         if (seen_this)
 365                                 break;
 366                         is_commit_in_columns = 0;
 367                         col_commit = graph->commit;
 368                 } else {
 369                         col_commit = graph->columns[i].commit;
 370                 }
 371
 372                 if (col_commit == graph->commit) {
 373                         int old_mapping_idx = mapping_idx;
 374                         seen_this = 1;
 375                         graph->commit_index = i;
 376                         for (parent = graph->commit->parents;
 377                              parent;
 378                              parent = parent->next) {
 379                                 graph_insert_into_new_columns(graph,
 380                                                               parent->item,
 381                                                               &mapping_idx);
 382                         }
 383                         /*
 384                          * We always need to increment mapping_idx by at
 385                          * least 2, even if it has no interesting parents.
 386                          * The current commit always takes up at least 2
 387                          * spaces.
 388                          */
 389                         if (mapping_idx == old_mapping_idx)
 390                                 mapping_idx += 2;
 391                 } else {
 392                         graph_insert_into_new_columns(graph, col_commit,
 393                                                       &mapping_idx);
 394                 }
 395         }
 396
 397         /*
 398          * Shrink mapping_size to be the minimum necessary
 399          */
 400         while (graph->mapping_size > 1 &&
 401                graph->mapping[graph->mapping_size - 1] < 0)
 402                 graph->mapping_size--;
 403
 404         /*
 405          * Compute graph->width for this commit
 406          */
 407         graph_update_width(graph, is_commit_in_columns);
 408 }
 409
 410 void graph_update(struct git_graph *graph, struct commit *commit)
 411 {
 412         struct commit_list *parent;
 413
 414         /*
 415          * Set the new commit
 416          */
 417         graph->commit = commit;
 418
 419         /*
 420          * Count how many interesting parents this commit has
 421          */
 422         graph->num_parents = 0;
 423         for (parent = commit->parents; parent; parent = parent->next) {
 424                 if (graph_is_interesting(graph, parent->item))
 425                         graph->num_parents++;
 426         }
 427
 428         /*
 429          * Store the old commit_index in prev_commit_index.
 430          * graph_update_columns() will update graph->commit_index for this
 431          * commit.
 432          */
 433         graph->prev_commit_index = graph->commit_index;
 434
 435         /*
 436          * Call graph_update_columns() to update
 437          * columns, new_columns, and mapping.
 438          */
 439         graph_update_columns(graph);
 440
 441         graph->expansion_row = 0;
 442
 443         /*
 444          * Update graph->state.
 445          * Note that we don't call graph_update_state() here, since
 446          * we don't want to update graph->prev_state.  No line for
 447          * graph->state was ever printed.
 448          *
 449          * If the previous commit didn't get to the GRAPH_PADDING state,
 450          * it never finished its output.  Goto GRAPH_SKIP, to print out
 451          * a line to indicate that portion of the graph is missing.
 452          *
 453          * Otherwise, if there are 3 or more parents, we need to print
 454          * extra rows before the commit, to expand the branch lines around
 455          * it and make room for it.
 456          *
 457          * If there are less than 3 parents, we can immediately print the
 458          * commit line.
 459          */
 460         if (graph->state != GRAPH_PADDING)
 461                 graph->state = GRAPH_SKIP;
 462         else if (graph->num_parents >= 3)
 463                 graph->state = GRAPH_PRE_COMMIT;
 464         else
 465                 graph->state = GRAPH_COMMIT;
 466 }
 467
 468 static int graph_is_mapping_correct(struct git_graph *graph)
 469 {
 470         int i;
 471
 472         /*
 473          * The mapping is up to date if each entry is at its target,
 474          * or is 1 greater than its target.
 475          * (If it is 1 greater than the target, '/' will be printed, so it
 476          * will look correct on the next row.)
 477          */
 478         for (i = 0; i < graph->mapping_size; i++) {
 479                 int target = graph->mapping[i];
 480                 if (target < 0)
 481                         continue;
 482                 if (target == (i / 2))
 483                         continue;
 484                 return 0;
 485         }
 486
 487         return 1;
 488 }
 489
 490 static void graph_pad_horizontally(struct git_graph *graph, struct strbuf *sb)
 491 {
 492         /*
 493          * Add additional spaces to the end of the strbuf, so that all
 494          * lines for a particular commit have the same width.
 495          *
 496          * This way, fields printed to the right of the graph will remain
 497          * aligned for the entire commit.
 498          */
 499         int extra;
 500         if (sb->len >= graph->width)
 501                 return;
 502
 503         extra = graph->width - sb->len;
 504         strbuf_addf(sb, "%*s", (int) extra, "");
 505 }
 506
 507 static void graph_output_padding_line(struct git_graph *graph,
 508                                       struct strbuf *sb)
 509 {
 510         int i;
 511
 512         /*
 513          * We could conceivable be called with a NULL commit
 514          * if our caller has a bug, and invokes graph_next_line()
 515          * immediately after graph_init(), without first calling
 516          * graph_update().  Return without outputting anything in this
 517          * case.
 518          */
 519         if (!graph->commit)
 520                 return;
 521
 522         /*
 523          * Output a padding row, that leaves all branch lines unchanged
 524          */
 525         for (i = 0; i < graph->num_new_columns; i++) {
 526                 strbuf_addstr(sb, "| ");
 527         }
 528
 529         graph_pad_horizontally(graph, sb);
 530 }
 531
 532 static void graph_output_skip_line(struct git_graph *graph, struct strbuf *sb)
 533 {
 534         /*
 535          * Output an ellipsis to indicate that a portion
 536          * of the graph is missing.
 537          */
 538         strbuf_addstr(sb, "...");
 539         graph_pad_horizontally(graph, sb);
 540
 541         if (graph->num_parents >= 3)
 542                 graph_update_state(graph, GRAPH_PRE_COMMIT);
 543         else
 544                 graph_update_state(graph, GRAPH_COMMIT);
 545 }
 546
 547 static void graph_output_pre_commit_line(struct git_graph *graph,
 548                                          struct strbuf *sb)
 549 {
 550         int num_expansion_rows;
 551         int i, seen_this;
 552
 553         /*
 554          * This function formats a row that increases the space around a commit
 555          * with multiple parents, to make room for it.  It should only be
 556          * called when there are 3 or more parents.
 557          *
 558          * We need 2 extra rows for every parent over 2.
 559          */
 560         assert(graph->num_parents >= 3);
 561         num_expansion_rows = (graph->num_parents - 2) * 2;
 562
 563         /*
 564          * graph->expansion_row tracks the current expansion row we are on.
 565          * It should be in the range [0, num_expansion_rows - 1]
 566          */
 567         assert(0 <= graph->expansion_row &&
 568                graph->expansion_row < num_expansion_rows);
 569
 570         /*
 571          * Output the row
 572          */
 573         seen_this = 0;
 574         for (i = 0; i < graph->num_columns; i++) {
 575                 struct column *col = &graph->columns[i];
 576                 if (col->commit == graph->commit) {
 577                         seen_this = 1;
 578                         strbuf_addf(sb, "| %*s", graph->expansion_row, "");
 579                 } else if (seen_this && (graph->expansion_row == 0)) {
 580                         /*
 581                          * This is the first line of the pre-commit output.
 582                          * If the previous commit was a merge commit and
 583                          * ended in the GRAPH_POST_MERGE state, all branch
 584                          * lines after graph->prev_commit_index were
 585                          * printed as "\" on the previous line.  Continue
 586                          * to print them as "\" on this line.  Otherwise,
 587                          * print the branch lines as "|".
 588                          */
 589                         if (graph->prev_state == GRAPH_POST_MERGE &&
 590                             graph->prev_commit_index < i)
 591                                 strbuf_addstr(sb, "\\ ");
 592                         else
 593                                 strbuf_addstr(sb, "| ");
 594                 } else if (seen_this && (graph->expansion_row > 0)) {
 595                         strbuf_addstr(sb, "\\ ");
 596                 } else {
 597                         strbuf_addstr(sb, "| ");
 598                 }
 599         }
 600
 601         graph_pad_horizontally(graph, sb);
 602
 603         /*
 604          * Increment graph->expansion_row,
 605          * and move to state GRAPH_COMMIT if necessary
 606          */
 607         graph->expansion_row++;
 608         if (graph->expansion_row >= num_expansion_rows)
 609                 graph_update_state(graph, GRAPH_COMMIT);
 610 }
 611
 612 static void graph_output_commit_char(struct git_graph *graph, struct strbuf *sb)
 613 {
 614         /*
 615          * For boundary commits, print 'o'
 616          * (We should only see boundary commits when revs->boundary is set.)
 617          */
 618         if (graph->commit->object.flags & BOUNDARY) {
 619                 assert(graph->revs->boundary);
 620                 strbuf_addch(sb, 'o');
 621                 return;
 622         }
 623
 624         /*
 625          * If revs->left_right is set, print '<' for commits that
 626          * come from the left side, and '>' for commits from the right
 627          * side.
 628          */
 629         if (graph->revs && graph->revs->left_right) {
 630                 if (graph->commit->object.flags & SYMMETRIC_LEFT)
 631                         strbuf_addch(sb, '<');
 632                 else
 633                         strbuf_addch(sb, '>');
 634                 return;
 635         }
 636
 637         /*
 638          * Print 'M' for merge commits
 639          *
 640          * Note that we don't check graph->num_parents to determine if the
 641          * commit is a merge, since that only tracks the number of
 642          * "interesting" parents.  We want to print 'M' for merge commits
 643          * even if they have less than 2 interesting parents.
 644          */
 645         if (graph->commit->parents != NULL &&
 646             graph->commit->parents->next != NULL) {
 647                 strbuf_addch(sb, 'M');
 648                 return;
 649         }
 650
 651         /*
 652          * Print '*' in all other cases
 653          */
 654         strbuf_addch(sb, '*');
 655 }
 656
 657 void graph_output_commit_line(struct git_graph *graph, struct strbuf *sb)
 658 {
 659         int seen_this = 0;
 660         int i, j;
 661
 662         /*
 663          * Output the row containing this commit
 664          * Iterate up to and including graph->num_columns,
 665          * since the current commit may not be in any of the existing
 666          * columns.  (This happens when the current commit doesn't have any
 667          * children that we have already processed.)
 668          */
 669         seen_this = 0;
 670         for (i = 0; i <= graph->num_columns; i++) {
 671                 struct commit *col_commit;
 672                 if (i == graph->num_columns) {
 673                         if (seen_this)
 674                                 break;
 675                         col_commit = graph->commit;
 676                 } else {
 677                         col_commit = graph->columns[i].commit;
 678                 }
 679
 680                 if (col_commit == graph->commit) {
 681                         seen_this = 1;
 682                         graph_output_commit_char(graph, sb);
 683
 684                         if (graph->num_parents < 3)
 685                                 strbuf_addch(sb, ' ');
 686                         else {
 687                                 int num_dashes =
 688                                         ((graph->num_parents - 2) * 2) - 1;
 689                                 for (j = 0; j < num_dashes; j++)
 690                                         strbuf_addch(sb, '-');
 691                                 strbuf_addstr(sb, ". ");
 692                         }
 693                 } else if (seen_this && (graph->num_parents > 2)) {
 694                         strbuf_addstr(sb, "\\ ");
 695                 } else if (seen_this && (graph->num_parents == 2)) {
 696                         /*
 697                          * This is a 2-way merge commit.
 698                          * There is no GRAPH_PRE_COMMIT stage for 2-way
 699                          * merges, so this is the first line of output
 700                          * for this commit.  Check to see what the previous
 701                          * line of output was.
 702                          *
 703                          * If it was GRAPH_POST_MERGE, the branch line
 704                          * coming into this commit may have been '\',
 705                          * and not '|' or '/'.  If so, output the branch
 706                          * line as '\' on this line, instead of '|'.  This
 707                          * makes the output look nicer.
 708                          */
 709                         if (graph->prev_state == GRAPH_POST_MERGE &&
 710                             graph->prev_commit_index < i)
 711                                 strbuf_addstr(sb, "\\ ");
 712                         else
 713                                 strbuf_addstr(sb, "| ");
 714                 } else {
 715                         strbuf_addstr(sb, "| ");
 716                 }
 717         }
 718
 719         graph_pad_horizontally(graph, sb);
 720
 721         /*
 722          * Update graph->state
 723          */
 724         if (graph->num_parents > 1)
 725                 graph_update_state(graph, GRAPH_POST_MERGE);
 726         else if (graph_is_mapping_correct(graph))
 727                 graph_update_state(graph, GRAPH_PADDING);
 728         else
 729                 graph_update_state(graph, GRAPH_COLLAPSING);
 730 }
 731
 732 void graph_output_post_merge_line(struct git_graph *graph, struct strbuf *sb)
 733 {
 734         int seen_this = 0;
 735         int i, j;
 736
 737         /*
 738          * Output the post-merge row
 739          */
 740         for (i = 0; i <= graph->num_columns; i++) {
 741                 struct commit *col_commit;
 742                 if (i == graph->num_columns) {
 743                         if (seen_this)
 744                                 break;
 745                         col_commit = graph->commit;
 746                 } else {
 747                         col_commit = graph->columns[i].commit;
 748                 }
 749
 750                 if (col_commit == graph->commit) {
 751                         seen_this = 1;
 752                         strbuf_addch(sb, '|');
 753                         for (j = 0; j < graph->num_parents - 1; j++)
 754                                 strbuf_addstr(sb, "\\ ");
 755                 } else if (seen_this) {
 756                         strbuf_addstr(sb, "\\ ");
 757                 } else {
 758                         strbuf_addstr(sb, "| ");
 759                 }
 760         }
 761
 762         graph_pad_horizontally(graph, sb);
 763
 764         /*
 765          * Update graph->state
 766          */
 767         if (graph_is_mapping_correct(graph))
 768                 graph_update_state(graph, GRAPH_PADDING);
 769         else
 770                 graph_update_state(graph, GRAPH_COLLAPSING);
 771 }
 772
 773 void graph_output_collapsing_line(struct git_graph *graph, struct strbuf *sb)
 774 {
 775         int i;
 776         int *tmp_mapping;
 777
 778         /*
 779          * Clear out the new_mapping array
 780          */
 781         for (i = 0; i < graph->mapping_size; i++)
 782                 graph->new_mapping[i] = -1;
 783
 784         for (i = 0; i < graph->mapping_size; i++) {
 785                 int target = graph->mapping[i];
 786                 if (target < 0)
 787                         continue;
 788
 789                 /*
 790                  * Since update_columns() always inserts the leftmost
 791                  * column first, each branch's target location should
 792                  * always be either its current location or to the left of
 793                  * its current location.
 794                  *
 795                  * We never have to move branches to the right.  This makes
 796                  * the graph much more legible, since whenever branches
 797                  * cross, only one is moving directions.
 798                  */
 799                 assert(target * 2 <= i);
 800
 801                 if (target * 2 == i) {
 802                         /*
 803                          * This column is already in the
 804                          * correct place
 805                          */
 806                         assert(graph->new_mapping[i] == -1);
 807                         graph->new_mapping[i] = target;
 808                 } else if (graph->new_mapping[i - 1] < 0) {
 809                         /*
 810                          * Nothing is to the left.
 811                          * Move to the left by one
 812                          */
 813                         graph->new_mapping[i - 1] = target;
 814                 } else if (graph->new_mapping[i - 1] == target) {
 815                         /*
 816                          * There is a branch line to our left
 817                          * already, and it is our target.  We
 818                          * combine with this line, since we share
 819                          * the same parent commit.
 820                          *
 821                          * We don't have to add anything to the
 822                          * output or new_mapping, since the
 823                          * existing branch line has already taken
 824                          * care of it.
 825                          */
 826                 } else {
 827                         /*
 828                          * There is a branch line to our left,
 829                          * but it isn't our target.  We need to
 830                          * cross over it.
 831                          *
 832                          * The space just to the left of this
 833                          * branch should always be empty.
 834                          */
 835                         assert(graph->new_mapping[i - 1] > target);
 836                         assert(graph->new_mapping[i - 2] < 0);
 837                         graph->new_mapping[i - 2] = target;
 838                 }
 839         }
 840
 841         /*
 842          * The new mapping may be 1 smaller than the old mapping
 843          */
 844         if (graph->new_mapping[graph->mapping_size - 1] < 0)
 845                 graph->mapping_size--;
 846
 847         /*
 848          * Output out a line based on the new mapping info
 849          */
 850         for (i = 0; i < graph->mapping_size; i++) {
 851                 int target = graph->new_mapping[i];
 852                 if (target < 0)
 853                         strbuf_addch(sb, ' ');
 854                 else if (target * 2 == i)
 855                         strbuf_addch(sb, '|');
 856                 else
 857                         strbuf_addch(sb, '/');
 858         }
 859
 860         graph_pad_horizontally(graph, sb);
 861
 862         /*
 863          * Swap mapping and new_mapping
 864          */
 865         tmp_mapping = graph->mapping;
 866         graph->mapping = graph->new_mapping;
 867         graph->new_mapping = tmp_mapping;
 868
 869         /*
 870          * If graph->mapping indicates that all of the branch lines
 871          * are already in the correct positions, we are done.
 872          * Otherwise, we need to collapse some branch lines together.
 873          */
 874         if (graph_is_mapping_correct(graph))
 875                 graph_update_state(graph, GRAPH_PADDING);
 876 }
 877
 878 int graph_next_line(struct git_graph *graph, struct strbuf *sb)
 879 {
 880         switch (graph->state) {
 881         case GRAPH_PADDING:
 882                 graph_output_padding_line(graph, sb);
 883                 return 0;
 884         case GRAPH_SKIP:
 885                 graph_output_skip_line(graph, sb);
 886                 return 0;
 887         case GRAPH_PRE_COMMIT:
 888                 graph_output_pre_commit_line(graph, sb);
 889                 return 0;
 890         case GRAPH_COMMIT:
 891                 graph_output_commit_line(graph, sb);
 892                 return 1;
 893         case GRAPH_POST_MERGE:
 894                 graph_output_post_merge_line(graph, sb);
 895                 return 0;
 896         case GRAPH_COLLAPSING:
 897                 graph_output_collapsing_line(graph, sb);
 898                 return 0;
 899         }
 900
 901         assert(0);
 902         return 0;
 903 }
 904
 905 void graph_padding_line(struct git_graph *graph, struct strbuf *sb)
 906 {
 907         int i, j;
 908
 909         if (graph->state != GRAPH_COMMIT) {
 910                 graph_next_line(graph, sb);
 911                 return;
 912         }
 913
 914         /*
 915          * Output the row containing this commit
 916          * Iterate up to and including graph->num_columns,
 917          * since the current commit may not be in any of the existing
 918          * columns.  (This happens when the current commit doesn't have any
 919          * children that we have already processed.)
 920          */
 921         for (i = 0; i < graph->num_columns; i++) {
 922                 struct commit *col_commit = graph->columns[i].commit;
 923                 if (col_commit == graph->commit) {
 924                         strbuf_addch(sb, '|');
 925
 926                         if (graph->num_parents < 3)
 927                                 strbuf_addch(sb, ' ');
 928                         else {
 929                                 int num_spaces = ((graph->num_parents - 2) * 2);
 930                                 for (j = 0; j < num_spaces; j++)
 931                                         strbuf_addch(sb, ' ');
 932                         }
 933                 } else {
 934                         strbuf_addstr(sb, "| ");
 935                 }
 936         }
 937
 938         graph_pad_horizontally(graph, sb);
 939
 940         /*
 941          * Update graph->prev_state since we have output a padding line
 942          */
 943         graph->prev_state = GRAPH_PADDING;
 944 }
 945
 946 int graph_is_commit_finished(struct git_graph const *graph)
 947 {
 948         return (graph->state == GRAPH_PADDING);
 949 }
 950
 951 void graph_show_commit(struct git_graph *graph)
 952 {
 953         struct strbuf msgbuf;
 954         int shown_commit_line = 0;
 955
 956         if (!graph)
 957                 return;
 958
 959         strbuf_init(&msgbuf, 0);
 960
 961         while (!shown_commit_line) {
 962                 shown_commit_line = graph_next_line(graph, &msgbuf);
 963                 fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
 964                 if (!shown_commit_line)
 965                         putchar('\n');
 966                 strbuf_setlen(&msgbuf, 0);
 967         }
 968
 969         strbuf_release(&msgbuf);
 970 }
 971
 972 void graph_show_oneline(struct git_graph *graph)
 973 {
 974         struct strbuf msgbuf;
 975
 976         if (!graph)
 977                 return;
 978
 979         strbuf_init(&msgbuf, 0);
 980         graph_next_line(graph, &msgbuf);
 981         fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
 982         strbuf_release(&msgbuf);
 983 }
 984
 985 void graph_show_padding(struct git_graph *graph)
 986 {
 987         struct strbuf msgbuf;
 988
 989         if (!graph)
 990                 return;
 991
 992         strbuf_init(&msgbuf, 0);
 993         graph_padding_line(graph, &msgbuf);
 994         fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
 995         strbuf_release(&msgbuf);
 996 }
 997
 998 int graph_show_remainder(struct git_graph *graph)
 999 {
1000         struct strbuf msgbuf;
1001         int shown = 0;
1002
1003         if (!graph)
1004                 return 0;
1005
1006         if (graph_is_commit_finished(graph))
1007                 return 0;
1008
1009         strbuf_init(&msgbuf, 0);
1010         for (;;) {
1011                 graph_next_line(graph, &msgbuf);
1012                 fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
1013                 strbuf_setlen(&msgbuf, 0);
1014                 shown = 1;
1015
1016                 if (!graph_is_commit_finished(graph))
1017                         putchar('\n');
1018                 else
1019                         break;
1020         }
1021         strbuf_release(&msgbuf);
1022
1023         return shown;
1024 }
1025
1026
1027 void graph_show_strbuf(struct git_graph *graph, struct strbuf const *sb)
1028 {
1029         char *p;
1030
1031         if (!graph) {
1032                 fwrite(sb->buf, sizeof(char), sb->len, stdout);
1033                 return;
1034         }
1035
1036         /*
1037          * Print the strbuf line by line,
1038          * and display the graph info before each line but the first.
1039          */
1040         p = sb->buf;
1041         while (p) {
1042                 size_t len;
1043                 char *next_p = strchr(p, '\n');
1044                 if (next_p) {
1045                         next_p++;
1046                         len = next_p - p;
1047                 } else {
1048                         len = (sb->buf + sb->len) - p;
1049                 }
1050                 fwrite(p, sizeof(char), len, stdout);
1051                 if (next_p && *next_p != '\0')
1052                         graph_show_oneline(graph);
1053                 p = next_p;
1054         }
1055 }
1056
1057 void graph_show_commit_msg(struct git_graph *graph,
1058                            struct strbuf const *sb)
1059 {
1060         int newline_terminated;
1061
1062         if (!graph) {
1063                 /*
1064                  * If there's no graph, just print the message buffer.
1065                  *
1066                  * The message buffer for CMIT_FMT_ONELINE and
1067                  * CMIT_FMT_USERFORMAT are already missing a terminating
1068                  * newline.  All of the other formats should have it.
1069                  */
1070                 fwrite(sb->buf, sizeof(char), sb->len, stdout);
1071                 return;
1072         }
1073
1074         newline_terminated = (sb->len && sb->buf[sb->len - 1] == '\n');
1075
1076         /*
1077          * Show the commit message
1078          */
1079         graph_show_strbuf(graph, sb);
1080
1081         /*
1082          * If there is more output needed for this commit, show it now
1083          */
1084         if (!graph_is_commit_finished(graph)) {
1085                 /*
1086                  * If sb doesn't have a terminating newline, print one now,
1087                  * so we can start the remainder of the graph output on a
1088                  * new line.
1089                  */
1090                 if (!newline_terminated)
1091                         putchar('\n');
1092
1093                 graph_show_remainder(graph);
1094
1095                 /*
1096                  * If sb ends with a newline, our output should too.
1097                  */
1098                 if (newline_terminated)
1099                         putchar('\n');
1100         }
1101 }