notes.hon commit Teach builtin-notes to remove empty notes (a0b4dfa)
   1#ifndef NOTES_H
   2#define NOTES_H
   3
   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 *
  15 * The two given SHA1s must both be non-NULL and different from each other.
  16 *
  17 * The default combine_notes function (you get this when passing NULL) is
  18 * combine_notes_concatenate(), which appends the contents of the new note to
  19 * the contents of the existing note.
  20 */
  21typedef int combine_notes_fn(unsigned char *cur_sha1, const unsigned char *new_sha1);
  22
  23/* Common notes combinators */
  24int combine_notes_concatenate(unsigned char *cur_sha1, const unsigned char *new_sha1);
  25int combine_notes_overwrite(unsigned char *cur_sha1, const unsigned char *new_sha1);
  26int combine_notes_ignore(unsigned char *cur_sha1, const unsigned char *new_sha1);
  27
  28/*
  29 * Notes tree object
  30 *
  31 * Encapsulates the internal notes tree structure associated with a notes ref.
  32 * Whenever a struct notes_tree pointer is required below, you may pass NULL in
  33 * order to use the default/internal notes tree. E.g. you only need to pass a
  34 * non-NULL value if you need to refer to several different notes trees
  35 * simultaneously.
  36 */
  37extern struct notes_tree {
  38        struct int_node *root;
  39        struct non_note *first_non_note, *prev_non_note;
  40        char *ref;
  41        combine_notes_fn *combine_notes;
  42        int initialized;
  43} default_notes_tree;
  44
  45/*
  46 * Flags controlling behaviour of notes tree initialization
  47 *
  48 * Default behaviour is to initialize the notes tree from the tree object
  49 * specified by the given (or default) notes ref.
  50 */
  51#define NOTES_INIT_EMPTY 1
  52
  53/*
  54 * Initialize the given notes_tree with the notes tree structure at the given
  55 * ref. If given ref is NULL, the value of the $GIT_NOTES_REF environment
  56 * variable is used, and if that is missing, the default notes ref is used
  57 * ("refs/notes/commits").
  58 *
  59 * If you need to re-intialize a notes_tree structure (e.g. when switching from
  60 * one notes ref to another), you must first de-initialize the notes_tree
  61 * structure by calling free_notes(struct notes_tree *).
  62 *
  63 * If you pass t == NULL, the default internal notes_tree will be initialized.
  64 *
  65 * The combine_notes function that is passed becomes the default combine_notes
  66 * function for the given notes_tree. If NULL is passed, the default
  67 * combine_notes function is combine_notes_concatenate().
  68 *
  69 * Precondition: The notes_tree structure is zeroed (this can be achieved with
  70 * memset(t, 0, sizeof(struct notes_tree)))
  71 */
  72void init_notes(struct notes_tree *t, const char *notes_ref,
  73                combine_notes_fn combine_notes, int flags);
  74
  75/*
  76 * Add the given note object to the given notes_tree structure
  77 *
  78 * IMPORTANT: The changes made by add_note() to the given notes_tree structure
  79 * are not persistent until a subsequent call to write_notes_tree() returns
  80 * zero.
  81 */
  82void add_note(struct notes_tree *t, const unsigned char *object_sha1,
  83                const unsigned char *note_sha1, combine_notes_fn combine_notes);
  84
  85/*
  86 * Remove the given note object from the given notes_tree structure
  87 *
  88 * IMPORTANT: The changes made by remove_note() to the given notes_tree
  89 * structure are not persistent until a subsequent call to write_notes_tree()
  90 * returns zero.
  91 */
  92void remove_note(struct notes_tree *t, const unsigned char *object_sha1);
  93
  94/*
  95 * Get the note object SHA1 containing the note data for the given object
  96 *
  97 * Return NULL if the given object has no notes.
  98 */
  99const unsigned char *get_note(struct notes_tree *t,
 100                const unsigned char *object_sha1);
 101
 102/*
 103 * Flags controlling behaviour of for_each_note()
 104 *
 105 * Default behaviour of for_each_note() is to traverse every single note object
 106 * in the given notes tree, unpacking subtree entries along the way.
 107 * The following flags can be used to alter the default behaviour:
 108 *
 109 * - DONT_UNPACK_SUBTREES causes for_each_note() NOT to unpack and recurse into
 110 *   subtree entries while traversing the notes tree. This causes notes within
 111 *   those subtrees NOT to be passed to the callback. Use this flag if you
 112 *   don't want to traverse _all_ notes, but only want to traverse the parts
 113 *   of the notes tree that have already been unpacked (this includes at least
 114 *   all notes that have been added/changed).
 115 *
 116 * - YIELD_SUBTREES causes any subtree entries that are encountered to be
 117 *   passed to the callback, before recursing into them. Subtree entries are
 118 *   not note objects, but represent intermediate directories in the notes
 119 *   tree. When passed to the callback, subtree entries will have a trailing
 120 *   slash in their path, which the callback may use to differentiate between
 121 *   note entries and subtree entries. Note that already-unpacked subtree
 122 *   entries are not part of the notes tree, and will therefore not be yielded.
 123 *   If this flag is used together with DONT_UNPACK_SUBTREES, for_each_note()
 124 *   will yield the subtree entry, but not recurse into it.
 125 */
 126#define FOR_EACH_NOTE_DONT_UNPACK_SUBTREES 1
 127#define FOR_EACH_NOTE_YIELD_SUBTREES 2
 128
 129/*
 130 * Invoke the specified callback function for each note in the given notes_tree
 131 *
 132 * If the callback returns nonzero, the note walk is aborted, and the return
 133 * value from the callback is returned from for_each_note(). Hence, a zero
 134 * return value from for_each_note() indicates that all notes were walked
 135 * successfully.
 136 *
 137 * IMPORTANT: The callback function is NOT allowed to change the notes tree.
 138 * In other words, the following functions can NOT be invoked (on the current
 139 * notes tree) from within the callback:
 140 * - add_note()
 141 * - remove_note()
 142 * - free_notes()
 143 */
 144typedef int each_note_fn(const unsigned char *object_sha1,
 145                const unsigned char *note_sha1, char *note_path,
 146                void *cb_data);
 147int for_each_note(struct notes_tree *t, int flags, each_note_fn fn,
 148                void *cb_data);
 149
 150/*
 151 * Write the given notes_tree structure to the object database
 152 *
 153 * Creates a new tree object encapsulating the current state of the given
 154 * notes_tree, and stores its SHA1 into the 'result' argument.
 155 *
 156 * Returns zero on success, non-zero on failure.
 157 *
 158 * IMPORTANT: Changes made to the given notes_tree are not persistent until
 159 * this function has returned zero. Please also remember to create a
 160 * corresponding commit object, and update the appropriate notes ref.
 161 */
 162int write_notes_tree(struct notes_tree *t, unsigned char *result);
 163
 164/*
 165 * Free (and de-initialize) the given notes_tree structure
 166 *
 167 * IMPORTANT: Changes made to the given notes_tree since the last, successful
 168 * call to write_notes_tree() will be lost.
 169 */
 170void free_notes(struct notes_tree *t);
 171
 172/* Flags controlling how notes are formatted */
 173#define NOTES_SHOW_HEADER 1
 174#define NOTES_INDENT 2
 175
 176/*
 177 * Fill the given strbuf with the notes associated with the given object.
 178 *
 179 * If the given notes_tree structure is not initialized, it will be auto-
 180 * initialized to the default value (see documentation for init_notes() above).
 181 * If the given notes_tree is NULL, the internal/default notes_tree will be
 182 * used instead.
 183 *
 184 * 'flags' is a bitwise combination of the above formatting flags.
 185 */
 186void format_note(struct notes_tree *t, const unsigned char *object_sha1,
 187                struct strbuf *sb, const char *output_encoding, int flags);
 188
 189#endif