- Created by Barbara Jones, last modified on Feb 19, 2020
H5L_ITERATE2
Iterates through links in a group
Procedure:
H5L_ITERATE2 ( group_id, idx_type, order, idx_p, op, op_data )
Signature:
herr_t H5Literate2 ( hid_t group_id, H5_index_t idx_type, H5_iter_order_t order,
hsize_t *idx_p, H5L_iterate2_t op, void *op_data )
SUBROUTINE h5literate_f(group,index_type, order, position,
op, ctx, return_value, hdferr)
INTEGER(HID_T) , INTENT(IN) :: group
INTEGER , INTENT(IN) :: index_type
INTEGER , INTENT(IN) :: order
INTEGER(HSIZE_T), INTENT(INOUT) :: position
TYPE(C_FUNPTR) , INTENT(IN) :: op
TYPE(C_PTR) , INTENT(IN) :: ctx
INTEGER , INTENT(OUT) :: return_value
INTEGER , INTENT(OUT) :: hdferrParameters:
| Name | Mode | Kind | Description |
|---|---|---|---|
| group_id | IN | handle | File or group identifier |
| idx_type | IN | choice | Index for iteration order |
| order | IN | choice | Traversal order |
| idx_p | INOUT | integer | Iteration position |
| op | IN | delegate | User-defined operator |
| op_data | INOUT | opaque | User-supplied context |
Description:
H5L_ITERATE2 iterates through the links in a file or group, group_id, in the order of the specified index, idx_type, using a user-defined callback routine op. H5L_ITERATE2 does not recursively follow links into subgroups of the specified group.
Three parameters are used to manage progress of the iteration: idx_type, order, and idx_p.
idx_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 unnecessary, so the iteration may begin more quickly.
The choices for idx_type are:
| Name | Meaning |
|---|---|
| H5_INDEX_NAME | Lexicographic order |
| H5_INDEX_CRT_ORDER | Creation order |
order specifies the order in which objects are to be inspected along the index idx_type. The choices for order are:
| Name | Meaning |
|---|---|
| H5_ITER_INC | Increasing order |
| H5_ITER_DEC | Decreasing order |
| H5_ITER_NATIVE | Fastest order |
idx_p tracks the iteration and allows an iteration to be resumed if it was stopped before all members were processed. It is passed in by the application with a starting point and returned by the library with the point at which the iteration stopped.
op_data 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 op callback function’s op_data parameter.
op is invoked for each link encounter:
Signature:
herr_t (*H5L_iterate2_t)
(
hid_t group,
const char* name,
const H5L_info2_t* info,
void* op_data
)
Info:
typedef struct {
H5L_type_t type; /* Type of link */
hbool_t corder_valid; /* Indicate if creation order is valid */
int64_t corder; /* Creation order */
H5T_cset_t cset; /* Character set of link name */
union {
H5O_token_t token; /* Token of location that hard link points to */
size_t val_size; /* Size of a soft link or UD link value */
} u;
} H5L_info2_t;
typedef enum {
H5L_TYPE_ERROR = (-1), /* Invalid link type id */
H5L_TYPE_HARD = 0, /* Hard link id */
H5L_TYPE_SOFT = 1, /* Soft link id */
H5L_TYPE_EXTERNAL = 64, /* External link id */
H5L_TYPE_MAX = 255 /* Maximum link type id */
} H5L_type_t;
/*
* Character set to use for text strings. Do not change these values since
* they appear in HDF5 files!
*/
typedef enum H5T_cset_t {
H5T_CSET_ERROR = -1, /*error */
H5T_CSET_ASCII = 0, /*US ASCII */
H5T_CSET_UTF8 = 1, /*UTF-8 Unicode encoding */
H5T_CSET_RESERVED_2 = 2, /*reserved for later use */
H5T_CSET_RESERVED_3 = 3, /*reserved for later use */
H5T_CSET_RESERVED_4 = 4, /*reserved for later use */
H5T_CSET_RESERVED_5 = 5, /*reserved for later use */
H5T_CSET_RESERVED_6 = 6, /*reserved for later use */
H5T_CSET_RESERVED_7 = 7, /*reserved for later use */
H5T_CSET_RESERVED_8 = 8, /*reserved for later use */
H5T_CSET_RESERVED_9 = 9, /*reserved for later use */
H5T_CSET_RESERVED_10 = 10, /*reserved for later use */
H5T_CSET_RESERVED_11 = 11, /*reserved for later use */
H5T_CSET_RESERVED_12 = 12, /*reserved for later use */
H5T_CSET_RESERVED_13 = 13, /*reserved for later use */
H5T_CSET_RESERVED_14 = 14, /*reserved for later use */
H5T_CSET_RESERVED_15 = 15 /*reserved for later use */
} H5T_cset_t;
/* Type for object tokens */
typedef struct H5O_token_t {
uint8_t __data[H5O_MAX_TOKEN_SIZE];
} H5O_token_t;
Returns:
| Return value | Meaning |
|---|---|
| 0 | Continue iteration |
| > 0 | Stop iteration; successful termination |
| < 0 | Stop iteration; abnormal termination |
op_data is passed to and from each iteration and can be used to supply or aggregate information across iterations.
The behavior of H5L_ITERATE2 is undefined if the link membership of group_id changes during the iteration. This does not limit the ability to change link destinations while iterating, but caution is advised.
For recursive behavior, see the following the H5L_VISIT functions.
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.
Example:
/*
* Use iterator to see the names of the objects in the root group.
*/
idx_f = H5Literate2(file, H5_INDEX_NAME, H5_ITER_INC, NULL, file_info, NULL);
!************************************************************
!
! This example shows how to iterate over group members using
! H5Literate.
!
! This file is intended for use with HDF5 Library version 1.8
! with --enable-fortran2003
!
!
!************************************************************
MODULE g_iterate
USE HDF5
USE ISO_C_BINDING
IMPLICIT NONE
CONTAINS
!************************************************************
!
! Operator function. Prints the name and type of the object
! being examined.
!
! ************************************************************
INTEGER FUNCTION op_func(loc_id, name, info, operator_data) bind(C)
USE HDF5
USE ISO_C_BINDING
IMPLICIT NONE
INTEGER(HID_T), VALUE :: loc_id
CHARACTER(LEN=1), DIMENSION(1:10) :: name ! must have LEN=1 for bind(C) strings
TYPE(C_PTR) :: info
TYPE(C_PTR) :: operator_data
INTEGER :: status, i, len
TYPE(H5O_info_t), TARGET :: infobuf
TYPE(C_PTR) :: ptr
CHARACTER(LEN=10) :: name_string
!
! Get type of the object and display its name and type.
! The name of the object is passed to this FUNCTION by
! the Library.
!
DO i = 1, 10
name_string(i:i) = name(i)(1:1)
ENDDO
CALL H5Oget_info_by_name_f(loc_id, name_string, infobuf, status)
! Include the string up to the C NULL CHARACTER
len = 0
DO
IF(name_string(len+1:len+1).EQ.C_NULL_CHAR.OR.len.GE.10) EXIT
len = len + 1
ENDDO
IF(infobuf%type.EQ.H5O_TYPE_GROUP_F)THEN
WRITE(*,*) "Group: ", name_string(1:len)
ELSE IF(infobuf%type.EQ.H5O_TYPE_DATASET_F)THEN
WRITE(*,*) "Dataset: ", name_string(1:len)
ELSE IF(infobuf%type.EQ.H5O_TYPE_NAMED_DATATYPE_F)THEN
WRITE(*,*) "Datatype: ", name_string(1:len)
ELSE
WRITE(*,*) "Unknown: ", name_string(1:len)
ENDIF
op_func = 0 ! return successful
END FUNCTION op_func
END MODULE g_iterate
PROGRAM main
USE HDF5
USE ISO_C_BINDING
USE g_iterate
IMPLICIT NONE
CHARACTER(LEN=17), PARAMETER :: filename = "h5ex_g_iterate.h5"
INTEGER(HID_T) :: file ! Handle
INTEGER :: status
TYPE(C_FUNPTR) :: funptr
TYPE(C_PTR) :: ptr
INTEGER(hsize_t) :: idx
INTEGER :: ret_value
!
! Initialize FORTRAN interface.
!
CALL h5open_f(status)
!
! Open file.
!
CALL H5Fopen_f(filename, H5F_ACC_RDONLY_F, file, status)
!
! Begin iteration.
!
WRITE(*,'(A)') "Objects in root group:"
idx = 0
funptr = C_FUNLOC(op_func) ! call back function
ptr = C_NULL_PTR
CALL H5Literate_f(file, H5_INDEX_NAME_F, H5_ITER_NATIVE_F, idx, funptr, ptr, ret_value, status)
!
! Close and release resources.
!
CALL H5Fclose_f(file, status)
END PROGRAM main
History:
| Release | Change |
|---|---|
| 1.12.0 | Function was introduced in this release. |
--- Last Modified: February 19, 2020 | 10:46 AM