Last modified: 24 August 2012
Name: H5Lvisit_by_name
Signature:
  herr_t `H5Lvisit_by_name`( hid_t `loc_id`, const char *`group_name`, H5_index_t `index_type`, H5_iter_order_t `order`, H5L_iterate_t `op`, void *`op_data`, hid_t `lapl_id` )

Purpose:
  Recursively visits all links starting from a specified group.

Description:
  `H5Lvisit_by_name` is a recursive iteration function to visit all links in and below a group in an HDF5 file, thus providing a mechanism for an application to perform a common set of operations across all of those links or a dynamically selected subset. For non-recursive iteration across the members of a group, see `H5Literate`.

  The group serving as the root of the iteration is specified by the `loc_id` / `group_name` parameter pair. `loc_id` specifies a file or group; `group_name` specifies either a group in the file (with an absolute name based in the file’s root group) or a group relative to `loc_id`. If `loc_id` fully specifies the group that is to serve as the root of the iteration, `group_name` should be `'.'` (a dot). (Note that when `loc_id` fully specifies the the group that is to serve as the root of the iteration, the user may wish to consider using `H5Lvisit` instead of `H5Lvisit_by_name`.)

  Two parameters are used to establish the iteration: `index_type` and `order`.

  `index_type` specifies the index to be used. If the links have not been indexed by the index type, they will first be sorted by that index then the iteration will begin; if the links have been so indexed, the sorting step will be unnecesary, so the iteration may begin more quickly. Valid values include the following:

  | `H5_INDEX_NAME` | Alpha-numeric index on name
  | `H5_INDEX_CRT_ORDER` | Index on creation order

  Note that the index type passed in `index_type` is a best effort setting. If the application passes in a value indicating iteration in creation order and a group is encountered that was not tracked in creation order, that group will be iterated over in alpha-numeric order by name, or name order. (Name order is the native order used by the HDF5 Library and is always available.)

  `order` specifies the order in which objects are to be inspected along the index specified in `index_type`. Valid values include the following:

  | `H5_ITER_INC` | Increasing order
  | `H5_ITER_DEC` | Decreasing order
  | `H5_ITER_NATIVE` | Fastest available order

  The `op` callback funtion, the related H5L_info_t struct, and the effect that the callback function’s return value has on the application are described in `H5Lvisit`.

  The `H5Lvisit_by_name` `op_data` parameter is a user-defined pointer to the data required to process links in the course of the iteration. This pointer is passed back to each step of the iteration in the callback function’s `op_data` parameter.

  `lapl_id` is a link access property list. In the general case, when default link access properties are acceptable, this can be passed in as `H5P_DEFAULT`. An example of a situation that requires a non-default link access property list is when the link is an external link; an external link may require that a link prefix be set in a link access property list (see `H5Pset_elink_prefix`).

  `H5Lvisit_by_name` and `H5Ovisit_by_name` are companion functions: one for examining and operating on links; the other for examining and operating on the objects that those links point to. Both functions ensure that by the time the function completes successfully, every link or object below the specified point in the file has been presented to the application for whatever processing the application requires.

Parameters:

  hid_t `loc_id` | IN: Identifier of a file or group
  const char *`name` | IN: Name of the group, generally relative to `loc_id`, that will serve as root of the iteration
  H5_index_t `index_type` | IN: Type of index; valid values include: `H5_INDEX_NAME` `H5_INDEX_CRT_ORDER`
  H5_iter_order_t `order` | IN: Order in which index is traversed; valid values include: `H5_ITER_DEC` `H5_ITER_INC` `H5_ITER_NATIVE`
  H5L_iterate_t `op` | IN: Callback function passing data regarding the link to the calling application
  void *`op_data` | IN: User-defined pointer to data required by the application for its processing of the link
  hid_t `lapl_id` | IN: Link access property list identifier

Returns:
  On success, returns the return value of the first operator that returns a positive value, or zero if all members were processed with no operator returning non-zero.

  On failure, returns a negative value if something goes wrong within the library, or the first negative value returned by an operator.

Fortran90 Interface:
  None.

History:

  Release | C
  1.8.0 | Function introduced in this release.