zdir_patch(3)
=============

NAME
----
zdir_patch - work with directory patches

SYNOPSIS
--------
----
//  This is a stable class, and may not change except for emergencies. It
//  is provided in stable builds.
#define ZDIR_PATCH_CREATE 1                 // Creates a new file
#define ZDIR_PATCH_DELETE 2                 // Delete a file

//  Create new patch
CZMQ_EXPORT zdir_patch_t *
    zdir_patch_new (const char *path, zfile_t *file, int op, const char *alias);

//  Destroy a patch
CZMQ_EXPORT void
    zdir_patch_destroy (zdir_patch_t **self_p);

//  Create copy of a patch. If the patch is null, or memory was exhausted,
//  returns null.                                                         
//  Caller owns return value and must destroy it when done.
CZMQ_EXPORT zdir_patch_t *
    zdir_patch_dup (zdir_patch_t *self);

//  Return patch file directory path
CZMQ_EXPORT const char *
    zdir_patch_path (zdir_patch_t *self);

//  Return patch file item
CZMQ_EXPORT zfile_t *
    zdir_patch_file (zdir_patch_t *self);

//  Return operation
CZMQ_EXPORT int
    zdir_patch_op (zdir_patch_t *self);

//  Return patch virtual file path
CZMQ_EXPORT const char *
    zdir_patch_vpath (zdir_patch_t *self);

//  Calculate hash digest for file (create only)
CZMQ_EXPORT void
    zdir_patch_digest_set (zdir_patch_t *self);

//  Return hash digest for patch file
CZMQ_EXPORT const char *
    zdir_patch_digest (zdir_patch_t *self);

//  Self test of this class.
CZMQ_EXPORT void
    zdir_patch_test (bool verbose);

----

DESCRIPTION
-----------

The zdir_patch class works with one patch, which says "create this
file" or "delete this file" (referring to a zfile item each time).

Please add @discuss section in ../src/zdir_patch.c.

EXAMPLE
-------
.From zdir_patch_test method
----
zfile_t *file = zfile_new (".", "bilbo");
assert (file);
zdir_patch_t *patch = zdir_patch_new (".", file, patch_create, "/");
assert (patch);
zfile_destroy (&file);

file = zdir_patch_file (patch);
assert (file);
assert (streq (zfile_filename (file, "."), "bilbo"));
assert (streq (zdir_patch_vpath (patch), "/bilbo"));
zdir_patch_destroy (&patch);
----
