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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 */
103struct 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 */
115void 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 */
135void graph_set_column_colors(const char **colors, unsigned short colors_max);
136
137/*
138 * Create a new struct git_graph.
139 */
140struct git_graph *graph_init(struct rev_info *opt);
141
142/*
143 * Free a struct git_graph.
144 */
145void 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 */
171void 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 */
187int 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 */
201int 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 */
207int 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 */
219void 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 */
225void 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 */
231void 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 */
238int 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 */
261void graph_show_commit_msg(struct git_graph *graph,
262 FILE *file,
263 struct strbuf const *sb);
264
265#endif /* GRAPH_H */