notes.h

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