notes.h/c: Allow combine_notes functions to remove notes
[git/git.git] / notes.h
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1#ifndef NOTES_H
2#define NOTES_H
3
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4/*
5 * Function type for combining two notes annotating the same object.
6 *
7 * When adding a new note annotating the same object as an existing note, it is
8 * up to the caller to decide how to combine the two notes. The decision is
9 * made by passing in a function of the following form. The function accepts
10 * two SHA1s -- of the existing note and the new note, respectively. The
11 * function then combines the notes in whatever way it sees fit, and writes the
12 * resulting SHA1 into the first SHA1 argument (cur_sha1). A non-zero return
13 * value indicates failure.
14 *
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15 * The two given SHA1s shall both be non-NULL and different from each other.
16 * Either of them (but not both) may be == null_sha1, which indicates an
17 * empty/non-existent note. If the resulting SHA1 (cur_sha1) is == null_sha1,
18 * the note will be removed from the notes tree.
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19 *
20 * The default combine_notes function (you get this when passing NULL) is
21 * combine_notes_concatenate(), which appends the contents of the new note to
22 * the contents of the existing note.
23 */
4e0d7a80 24typedef int (*combine_notes_fn)(unsigned char *cur_sha1, const unsigned char *new_sha1);
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25
26/* Common notes combinators */
27int combine_notes_concatenate(unsigned char *cur_sha1, const unsigned char *new_sha1);
28int combine_notes_overwrite(unsigned char *cur_sha1, const unsigned char *new_sha1);
29int combine_notes_ignore(unsigned char *cur_sha1, const unsigned char *new_sha1);
30
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31/*
32 * Notes tree object
33 *
34 * Encapsulates the internal notes tree structure associated with a notes ref.
35 * Whenever a struct notes_tree pointer is required below, you may pass NULL in
36 * order to use the default/internal notes tree. E.g. you only need to pass a
37 * non-NULL value if you need to refer to several different notes trees
38 * simultaneously.
39 */
40extern struct notes_tree {
41 struct int_node *root;
851c2b37 42 struct non_note *first_non_note, *prev_non_note;
cd305392 43 char *ref;
4e0d7a80 44 combine_notes_fn combine_notes;
cd305392 45 int initialized;
7f710ea9 46 int dirty;
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47} default_notes_tree;
48
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49/*
50 * Return the default notes ref.
51 *
52 * The default notes ref is the notes ref that is used when notes_ref == NULL
53 * is passed to init_notes().
54 *
55 * This the first of the following to be defined:
56 * 1. The '--ref' option to 'git notes', if given
57 * 2. The $GIT_NOTES_REF environment variable, if set
58 * 3. The value of the core.notesRef config variable, if set
59 * 4. GIT_NOTES_DEFAULT_REF (i.e. "refs/notes/commits")
60 */
61const char *default_notes_ref(void);
62
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63/*
64 * Flags controlling behaviour of notes tree initialization
65 *
66 * Default behaviour is to initialize the notes tree from the tree object
67 * specified by the given (or default) notes ref.
68 */
69#define NOTES_INIT_EMPTY 1
70
71/*
cd305392 72 * Initialize the given notes_tree with the notes tree structure at the given
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73 * ref. If given ref is NULL, the value of the $GIT_NOTES_REF environment
74 * variable is used, and if that is missing, the default notes ref is used
75 * ("refs/notes/commits").
76 *
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77 * If you need to re-intialize a notes_tree structure (e.g. when switching from
78 * one notes ref to another), you must first de-initialize the notes_tree
79 * structure by calling free_notes(struct notes_tree *).
80 *
81 * If you pass t == NULL, the default internal notes_tree will be initialized.
82 *
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83 * The combine_notes function that is passed becomes the default combine_notes
84 * function for the given notes_tree. If NULL is passed, the default
85 * combine_notes function is combine_notes_concatenate().
86 *
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87 * Precondition: The notes_tree structure is zeroed (this can be achieved with
88 * memset(t, 0, sizeof(struct notes_tree)))
709f79b0 89 */
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90void init_notes(struct notes_tree *t, const char *notes_ref,
91 combine_notes_fn combine_notes, int flags);
709f79b0 92
61a7cca0 93/*
cd305392 94 * Add the given note object to the given notes_tree structure
61a7cca0 95 *
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96 * If there already exists a note for the given object_sha1, the given
97 * combine_notes function is invoked to break the tie. If not given (i.e.
98 * combine_notes == NULL), the default combine_notes function for the given
99 * notes_tree is used.
100 *
101 * Passing note_sha1 == null_sha1 indicates the addition of an
102 * empty/non-existent note. This is a (potentially expensive) no-op unless
103 * there already exists a note for the given object_sha1, AND combining that
104 * note with the empty note (using the given combine_notes function) results
105 * in a new/changed note.
106 *
cd305392 107 * IMPORTANT: The changes made by add_note() to the given notes_tree structure
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108 * are not persistent until a subsequent call to write_notes_tree() returns
109 * zero.
110 */
cd305392 111void add_note(struct notes_tree *t, const unsigned char *object_sha1,
73f464b5 112 const unsigned char *note_sha1, combine_notes_fn combine_notes);
2626b536 113
61a7cca0 114/*
cd305392 115 * Remove the given note object from the given notes_tree structure
61a7cca0 116 *
cd305392 117 * IMPORTANT: The changes made by remove_note() to the given notes_tree
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118 * structure are not persistent until a subsequent call to write_notes_tree()
119 * returns zero.
120 */
cd305392 121void remove_note(struct notes_tree *t, const unsigned char *object_sha1);
1ec666b0 122
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123/*
124 * Get the note object SHA1 containing the note data for the given object
125 *
126 * Return NULL if the given object has no notes.
127 */
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128const unsigned char *get_note(struct notes_tree *t,
129 const unsigned char *object_sha1);
9b391f21 130
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131/*
132 * Copy a note from one object to another in the given notes_tree.
133 *
134 * Fails if the to_obj already has a note unless 'force' is true.
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135 *
136 * IMPORTANT: The changes made by copy_note() to the given notes_tree structure
137 * are not persistent until a subsequent call to write_notes_tree() returns
138 * zero.
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139 */
140int copy_note(struct notes_tree *t,
141 const unsigned char *from_obj, const unsigned char *to_obj,
142 int force, combine_notes_fn combine_fn);
143
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144/*
145 * Flags controlling behaviour of for_each_note()
146 *
147 * Default behaviour of for_each_note() is to traverse every single note object
cd305392 148 * in the given notes tree, unpacking subtree entries along the way.
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149 * The following flags can be used to alter the default behaviour:
150 *
151 * - DONT_UNPACK_SUBTREES causes for_each_note() NOT to unpack and recurse into
152 * subtree entries while traversing the notes tree. This causes notes within
153 * those subtrees NOT to be passed to the callback. Use this flag if you
154 * don't want to traverse _all_ notes, but only want to traverse the parts
155 * of the notes tree that have already been unpacked (this includes at least
156 * all notes that have been added/changed).
157 *
158 * - YIELD_SUBTREES causes any subtree entries that are encountered to be
159 * passed to the callback, before recursing into them. Subtree entries are
160 * not note objects, but represent intermediate directories in the notes
161 * tree. When passed to the callback, subtree entries will have a trailing
162 * slash in their path, which the callback may use to differentiate between
163 * note entries and subtree entries. Note that already-unpacked subtree
164 * entries are not part of the notes tree, and will therefore not be yielded.
165 * If this flag is used together with DONT_UNPACK_SUBTREES, for_each_note()
166 * will yield the subtree entry, but not recurse into it.
167 */
168#define FOR_EACH_NOTE_DONT_UNPACK_SUBTREES 1
169#define FOR_EACH_NOTE_YIELD_SUBTREES 2
170
171/*
cd305392 172 * Invoke the specified callback function for each note in the given notes_tree
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173 *
174 * If the callback returns nonzero, the note walk is aborted, and the return
175 * value from the callback is returned from for_each_note(). Hence, a zero
176 * return value from for_each_note() indicates that all notes were walked
177 * successfully.
178 *
179 * IMPORTANT: The callback function is NOT allowed to change the notes tree.
180 * In other words, the following functions can NOT be invoked (on the current
181 * notes tree) from within the callback:
182 * - add_note()
183 * - remove_note()
55d06077 184 * - copy_note()
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185 * - free_notes()
186 */
187typedef int each_note_fn(const unsigned char *object_sha1,
188 const unsigned char *note_sha1, char *note_path,
189 void *cb_data);
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190int for_each_note(struct notes_tree *t, int flags, each_note_fn fn,
191 void *cb_data);
73f77b90 192
61a7cca0 193/*
cd305392 194 * Write the given notes_tree structure to the object database
61a7cca0 195 *
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196 * Creates a new tree object encapsulating the current state of the given
197 * notes_tree, and stores its SHA1 into the 'result' argument.
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198 *
199 * Returns zero on success, non-zero on failure.
200 *
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201 * IMPORTANT: Changes made to the given notes_tree are not persistent until
202 * this function has returned zero. Please also remember to create a
203 * corresponding commit object, and update the appropriate notes ref.
61a7cca0 204 */
cd305392 205int write_notes_tree(struct notes_tree *t, unsigned char *result);
61a7cca0 206
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207/* Flags controlling the operation of prune */
208#define NOTES_PRUNE_VERBOSE 1
209#define NOTES_PRUNE_DRYRUN 2
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210/*
211 * Remove all notes annotating non-existing objects from the given notes tree
212 *
213 * All notes in the given notes_tree that are associated with objects that no
214 * longer exist in the database, are removed from the notes tree.
215 *
216 * IMPORTANT: The changes made by prune_notes() to the given notes_tree
217 * structure are not persistent until a subsequent call to write_notes_tree()
218 * returns zero.
219 */
a9f2adff 220void prune_notes(struct notes_tree *t, int flags);
00fbe636 221
61a7cca0 222/*
cd305392 223 * Free (and de-initialize) the given notes_tree structure
61a7cca0 224 *
cd305392 225 * IMPORTANT: Changes made to the given notes_tree since the last, successful
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226 * call to write_notes_tree() will be lost.
227 */
cd305392 228void free_notes(struct notes_tree *t);
27d57564 229
a7e7eff6 230/* Flags controlling how notes are formatted */
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231#define NOTES_SHOW_HEADER 1
232#define NOTES_INDENT 2
233
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234/*
235 * Fill the given strbuf with the notes associated with the given object.
236 *
cd305392 237 * If the given notes_tree structure is not initialized, it will be auto-
a7e7eff6 238 * initialized to the default value (see documentation for init_notes() above).
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239 * If the given notes_tree is NULL, the internal/default notes_tree will be
240 * used instead.
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241 *
242 * 'flags' is a bitwise combination of the above formatting flags.
243 */
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244void format_note(struct notes_tree *t, const unsigned char *object_sha1,
245 struct strbuf *sb, const char *output_encoding, int flags);
a97a7468 246
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247
248struct string_list;
249
250struct display_notes_opt {
a751b5cc 251 unsigned int suppress_default_notes:1;
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252 struct string_list *extra_notes_refs;
253};
254
255/*
256 * Load the notes machinery for displaying several notes trees.
257 *
258 * If 'opt' is not NULL, then it specifies additional settings for the
259 * displaying:
260 *
261 * - suppress_default_notes indicates that the notes from
262 * core.notesRef and notes.displayRef should not be loaded.
263 *
264 * - extra_notes_refs may contain a list of globs (in the same style
265 * as notes.displayRef) where notes should be loaded from.
266 */
267void init_display_notes(struct display_notes_opt *opt);
268
269/*
270 * Append notes for the given 'object_sha1' from all trees set up by
271 * init_display_notes() to 'sb'. The 'flags' are a bitwise
272 * combination of
273 *
274 * - NOTES_SHOW_HEADER: add a 'Notes (refname):' header
275 *
276 * - NOTES_INDENT: indent the notes by 4 places
277 *
278 * You *must* call init_display_notes() before using this function.
279 */
280void format_display_notes(const unsigned char *object_sha1,
281 struct strbuf *sb, const char *output_encoding, int flags);
282
283/*
284 * Load the notes tree from each ref listed in 'refs'. The output is
285 * an array of notes_tree*, terminated by a NULL.
286 */
287struct notes_tree **load_notes_trees(struct string_list *refs);
288
289/*
290 * Add all refs that match 'glob' to the 'list'.
291 */
292void string_list_add_refs_by_glob(struct string_list *list, const char *glob);
293
294/*
295 * Add all refs from a colon-separated glob list 'globs' to the end of
296 * 'list'. Empty components are ignored. This helper is used to
297 * parse GIT_NOTES_DISPLAY_REF style environment variables.
298 */
299void string_list_add_refs_from_colon_sep(struct string_list *list,
300 const char *globs);
301
a97a7468 302#endif