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h5a_attribute.go
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/
h5a_attribute.go
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// Copyright ©2017 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package hdf5
// #include "hdf5.h"
// #include <stdlib.h>
// #include <string.h>
import "C"
import (
"fmt"
"reflect"
"unsafe"
)
type Attribute struct {
Identifier
}
func newAttribute(id C.hid_t) *Attribute {
return &Attribute{Identifier{id}}
}
func createAttribute(id C.hid_t, name string, dtype *Datatype, dspace *Dataspace, acpl *PropList) (*Attribute, error) {
c_name := C.CString(name)
defer C.free(unsafe.Pointer(c_name))
hid := C.H5Acreate2(id, c_name, dtype.id, dspace.id, acpl.id, P_DEFAULT.id)
if err := checkID(hid); err != nil {
return nil, err
}
return newAttribute(hid), nil
}
func openAttribute(id C.hid_t, name string) (*Attribute, error) {
c_name := C.CString(name)
defer C.free(unsafe.Pointer(c_name))
hid := C.H5Aopen(id, c_name, P_DEFAULT.id)
if err := checkID(hid); err != nil {
return nil, err
}
return newAttribute(hid), nil
}
// Access the type of an attribute
func (s *Attribute) GetType() Identifier {
ftype := C.H5Aget_type(s.id)
return Identifier{ftype}
}
// Close releases and terminates access to an attribute.
func (s *Attribute) Close() error {
return s.closeWith(h5aclose)
}
func h5aclose(id C.hid_t) C.herr_t {
return C.H5Aclose(id)
}
// Space returns an identifier for a copy of the dataspace for a attribute.
func (s *Attribute) Space() *Dataspace {
hid := C.H5Aget_space(s.id)
if int(hid) > 0 {
return newDataspace(hid)
}
return nil
}
// Read reads raw data from a attribute into a buffer.
func (s *Attribute) Read(data interface{}, dtype *Datatype) error {
var (
addr unsafe.Pointer
rv = reflect.ValueOf(data)
)
if rv.Kind() != reflect.Ptr {
return fmt.Errorf("hdf5: read expects a pointer value")
}
v := reflect.Indirect(rv)
switch v.Kind() {
case reflect.Array:
addr = unsafe.Pointer(v.UnsafeAddr())
case reflect.String:
dtAttr, err := copyDatatype(s.GetType().id)
if err != nil {
return fmt.Errorf("hdf5: could not access attribute datatype: %v", err)
}
defer dtAttr.Close()
dtype = dtAttr
dlen := dtype.Size()
cstr := (*C.char)(unsafe.Pointer(C.malloc(C.size_t(uint(unsafe.Sizeof(byte(0))) * (dlen + 1)))))
defer C.free(unsafe.Pointer(cstr))
switch {
case C.H5Tis_variable_str(dtAttr.Identifier.id) != 0:
addr = unsafe.Pointer(&cstr)
default:
addr = unsafe.Pointer(cstr)
}
defer func() {
v.SetString(C.GoString(cstr))
}()
default:
addr = unsafe.Pointer(v.UnsafeAddr())
}
rc := C.H5Aread(s.id, dtype.id, addr)
err := h5err(rc)
return err
}
// Write writes raw data from a buffer to an attribute.
func (s *Attribute) Write(data interface{}, dtype *Datatype) error {
var addr unsafe.Pointer
v := reflect.Indirect(reflect.ValueOf(data))
switch v.Kind() {
case reflect.Array:
addr = unsafe.Pointer(v.UnsafeAddr())
case reflect.String:
str := C.CString(v.String())
defer C.free(unsafe.Pointer(str))
addr = unsafe.Pointer(&str)
case reflect.Ptr:
addr = unsafe.Pointer(v.Pointer())
default:
addr = unsafe.Pointer(v.UnsafeAddr())
}
rc := C.H5Awrite(s.id, dtype.id, addr)
err := h5err(rc)
return err
}