graph.h

   1 #ifndef GRAPH_H
   2 #define GRAPH_H
   3 #include "diff.h"
   4
   5 /**
   6  * The graph API is used to draw a text-based representation of the commit
   7  * history. The API generates the graph in a line-by-line fashion.
   8  *
   9  * Calling sequence
  10  * ----------------
  11  *
  12  * - Create a `struct git_graph` by calling `graph_init()`.  When using the
  13  *   revision walking API, this is done automatically by `setup_revisions()` if
  14  *   the '--graph' option is supplied.
  15  *
  16  * - Use the revision walking API to walk through a group of contiguous commits.
  17  *   The `get_revision()` function automatically calls `graph_update()` each time
  18  *   it is invoked.
  19  *
  20  * - For each commit, call `graph_next_line()` repeatedly, until
  21  *   `graph_is_commit_finished()` returns non-zero.  Each call to
  22  *   `graph_next_line()` will output a single line of the graph.  The resulting
  23  *   lines will not contain any newlines.  `graph_next_line()` returns 1 if the
  24  *   resulting line contains the current commit, or 0 if this is merely a line
  25  *   needed to adjust the graph before or after the current commit.  This return
  26  *   value can be used to determine where to print the commit summary information
  27  *   alongside the graph output.
  28  *
  29  * Limitations
  30  * -----------
  31  * - Check the graph_update() function for its limitations.
  32  *
  33  * - The graph API does not currently support reverse commit ordering.  In
  34  *   order to implement reverse ordering, the graphing API needs an
  35  *   (efficient) mechanism to find the children of a commit.
  36  *
  37  * Sample usage
  38  * ------------
  39  *
  40  * ------------
  41  * struct commit *commit;
  42  * struct git_graph *graph = graph_init(opts);
  43  *
  44  * while ((commit = get_revision(opts)) != NULL) {
  45  *      while (!graph_is_commit_finished(graph))
  46  *      {
  47  *              struct strbuf sb;
  48  *              int is_commit_line;
  49  *
  50  *              strbuf_init(&sb, 0);
  51  *              is_commit_line = graph_next_line(graph, &sb);
  52  *              fputs(sb.buf, stdout);
  53  *
  54  *              if (is_commit_line)
  55  *                      log_tree_commit(opts, commit);
  56  *              else
  57  *                      putchar(opts->diffopt.line_termination);
  58  *      }
  59  * }
  60  * ------------
  61  * Sample output
  62  * -------------
  63  *
  64  * The following is an example of the output from the graph API.  This output does
  65  * not include any commit summary information--callers are responsible for
  66  * outputting that information, if desired.
  67  * ------------
  68  * *
  69  * *
  70  * *
  71  * |\
  72  * * |
  73  * | | *
  74  * | \ \
  75  * |  \ \
  76  * *-. \ \
  77  * |\ \ \ \
  78  * | | * | |
  79  * | | | | | *
  80  * | | | | | *
  81  * | | | | | *
  82  * | | | | | |\
  83  * | | | | | | *
  84  * | * | | | | |
  85  * | | | | | *  \
  86  * | | | | | |\  |
  87  * | | | | * | | |
  88  * | | | | * | | |
  89  * * | | | | | | |
  90  * | |/ / / / / /
  91  * |/| / / / / /
  92  * * | | | | | |
  93  * |/ / / / / /
  94  * * | | | | |
  95  * | | | | | *
  96  * | | | | |/
  97  * | | | | *
  98  * ------------
  99  *
 100  */
 101
 102 /* A graph is a pointer to this opaque structure */
 103 struct git_graph;
 104
 105 /*
 106  * Called to setup global display of line_prefix diff option.
 107  *
 108  * Passed a diff_options structure which indicates the line_prefix and the
 109  * file to output the prefix to. This is sort of a hack used so that the
 110  * line_prefix will be honored by all flows which also honor "--graph"
 111  * regardless of whether a graph has actually been setup. The normal graph
 112  * flow will honor the exact diff_options passed, but a NULL graph will cause
 113  * display of a line_prefix to stdout.
 114  */
 115 void graph_setup_line_prefix(struct diff_options *diffopt);
 116
 117 /*
 118  * Set up a custom scheme for column colors.
 119  *
 120  * The default column color scheme inserts ANSI color escapes to colorize
 121  * the graph. The various color escapes are stored in an array of strings
 122  * where each entry corresponds to a color, except for the last entry,
 123  * which denotes the escape for resetting the color back to the default.
 124  * When generating the graph, strings from this array are inserted before
 125  * and after the various column characters.
 126  *
 127  * This function allows you to enable a custom array of color escapes.
 128  * The 'colors_max' argument is the index of the last "reset" entry.
 129  *
 130  * This functions must be called BEFORE graph_init() is called.
 131  *
 132  * NOTE: This function isn't used in Git outside graph.c but it is used
 133  * by CGit (https://git.zx2c4.com/cgit/) to use HTML for colors.
 134  */
 135 void graph_set_column_colors(const char **colors, unsigned short colors_max);
 136
 137 /*
 138  * Create a new struct git_graph.
 139  */
 140 struct git_graph *graph_init(struct rev_info *opt);
 141
 142 /*
 143  * Free a struct git_graph.
 144  */
 145 void graph_clear(struct git_graph *graph);
 146
 147 /*
 148  * Update a git_graph with a new commit.
 149  * This will cause the graph to begin outputting lines for the new commit
 150  * the next time graph_next_line() is called.
 151  *
 152  * If graph_update() is called before graph_is_commit_finished() returns 1,
 153  * the next call to graph_next_line() will output an ellipsis ("...")
 154  * to indicate that a portion of the graph is missing.
 155  *
 156  * Limitations:
 157  * -----------
 158  *
 159  * - `graph_update()` must be called with commits in topological order.  It should
 160  *   not be called on a commit if it has already been invoked with an ancestor of
 161  *   that commit, or the graph output will be incorrect.
 162  *
 163  * - `graph_update()` must be called on a contiguous group of commits.  If
 164  *   `graph_update()` is called on a particular commit, it should later be called
 165  *   on all parents of that commit.  Parents must not be skipped, or the graph
 166  *   output will appear incorrect.
 167  *
 168  * - `graph_update()` may be used on a pruned set of commits only if the parent list
 169  *   has been rewritten so as to include only ancestors from the pruned set.
 170  */
 171 void graph_update(struct git_graph *graph, struct commit *commit);
 172
 173 /*
 174  * Determine if a graph has finished outputting lines for the current
 175  * commit.
 176  *
 177  * Returns 1 if graph_next_line() needs to be called again before
 178  * graph_update() should be called.  Returns 0 if no more lines are needed
 179  * for this commit.  If 0 is returned, graph_next_line() may still be
 180  * called without calling graph_update(), and it will merely output
 181  * appropriate "vertical padding" in the graph.
 182  *
 183  * If `graph_update()` is called before all lines for the current commit have
 184  * been printed, the next call to `graph_next_line()` will output an ellipsis,
 185  * to indicate that a portion of the graph was omitted.
 186  */
 187 int graph_is_commit_finished(struct git_graph const *graph);
 188
 189 /*
 190  * Output the next line for a graph.
 191  * This formats the next graph line into the specified strbuf.  It is not
 192  * terminated with a newline.
 193  *
 194  * Returns 1 if the line includes the current commit, and 0 otherwise.
 195  * graph_next_line() will return 1 exactly once for each time
 196  * graph_update() is called.
 197  *
 198  * NOTE: This function isn't used in Git outside graph.c but it is used
 199  * by CGit (https://git.zx2c4.com/cgit/) to wrap HTML around graph lines.
 200  */
 201 int graph_next_line(struct git_graph *graph, struct strbuf *sb);
 202
 203
 204 /*
 205  * Return current width of the graph in on-screen characters.
 206  */
 207 int graph_width(struct git_graph *graph);
 208
 209 /*
 210  * graph_show_*: helper functions for printing to stdout
 211  */
 212
 213
 214 /*
 215  * If the graph is non-NULL, print the history graph to stdout,
 216  * up to and including the line containing this commit.
 217  * Does not print a terminating newline on the last line.
 218  */
 219 void graph_show_commit(struct git_graph *graph);
 220
 221 /*
 222  * If the graph is non-NULL, print one line of the history graph to stdout.
 223  * Does not print a terminating newline on the last line.
 224  */
 225 void graph_show_oneline(struct git_graph *graph);
 226
 227 /*
 228  * If the graph is non-NULL, print one line of vertical graph padding to
 229  * stdout.  Does not print a terminating newline on the last line.
 230  */
 231 void graph_show_padding(struct git_graph *graph);
 232
 233 /*
 234  * If the graph is non-NULL, print the rest of the history graph for this
 235  * commit to stdout.  Does not print a terminating newline on the last line.
 236  * Returns 1 if output was printed, and 0 if no output was necessary.
 237  */
 238 int graph_show_remainder(struct git_graph *graph);
 239
 240 /*
 241  * Print a commit message strbuf and the remainder of the graph to stdout.
 242  *
 243  * This is similar to graph_show_strbuf(), but it always prints the
 244  * remainder of the graph.
 245  *
 246  * It is better than directly calling `graph_show_strbuf()` followed by
 247  * `graph_show_remainder()` since it properly handles buffers that do not end in
 248  * a terminating newline.
 249  *
 250  * If the strbuf ends with a newline, the output printed by
 251  * graph_show_commit_msg() will end with a newline.  If the strbuf is
 252  * missing a terminating newline (including if it is empty), the output
 253  * printed by graph_show_commit_msg() will also be missing a terminating
 254  * newline.
 255  *
 256  * Note that unlike some other graph display functions, you must pass the file
 257  * handle directly. It is assumed that this is the same file handle as the
 258  * file specified by the graph diff options. This is necessary so that
 259  * graph_show_commit_msg can be called even with a NULL graph.
 260  */
 261 void graph_show_commit_msg(struct git_graph *graph,
 262                            FILE *file,
 263                            struct strbuf const *sb);
 264
 265 #endif /* GRAPH_H */