function status = h5_ref2obj
%H5_REF2OBJ This example shows how to create and store references to objects.
%   Program creates a file, two groups, a dataset to store integer data and
%   a dataset to store references to the objects. Stored references are
%   used to open the objects they are point to. Data is written to the
%   dereferenced dataset, and class type is displayed for the shared
%   datatype.
%
%   status is returned to indicate whether the example ran successfully

%   Copyright 2006 The MathWorks, Inc. 
%   $Revision: 1.1.4.1 $  $Date: 2006/05/10 19:51:08 $

% Initialize status to false
status = false;

fname = qeTempFile('h5');
filename   = fname.fullpath;      % file name 
dsetnamei  = 'INTEGERS';          % dataset with integer data 
dsetnamer  = 'OBJECT_REFERENCES'; % dataset with object references 
groupname1 = 'GROUP1';            % groups in the file 
groupname2 = 'GROUP2';

dims1 = 5;
dimsr = 4;
my_maxdims = 5; 
rank  = 1;
rankr = 1;
data  = int32(1:5);
    
%  Create file with default file access and file creation properties. 
fileid = H5F.create(filename, 'H5F_ACC_TRUNC', 'H5P_DEFAULT', 'H5P_DEFAULT');

% Create a group in the file.
grp1_id = H5G.create(fileid, groupname1, -1);

% Create a group inside the created gorup. 
grp2_id = H5G.create(grp1_id, groupname2, -1);

% Create dataspaces for datasets. 
space_id = H5S.create_simple(rank, dims1, my_maxdims);
spacer_id = H5S.create_simple(rankr, dimsr, []);

% Create integer dataset.
dset_id = H5D.create(fileid, dsetnamei, 'H5T_NATIVE_INT', space_id, 'H5P_DEFAULT');

% Create dataset to store references to the objects.
dsetr_id = H5D.create(fileid, dsetnamer, 'H5T_STD_REF_OBJ', spacer_id, 'H5P_DEFAULT');

% Create a datatype and store in the file.
type_id = H5T.copy('H5T_NATIVE_FLOAT');
H5T.commit(fileid, 'MYTYPE', type_id);

% Close dataspaces, groups and integer dataset.
H5S.close(space_id);
H5S.close(spacer_id);
H5T.close(type_id);
H5D.close(dset_id);
H5G.close(grp1_id);
H5G.close(grp2_id);

% Create references to two groups, integer dataset and shared datatype
% and write it to the dataset in the file.
ref(:,1) = H5R.create(fileid, groupname1, 'H5R_OBJECT', -1);
ref(:,2) = H5R.create(fileid, '/GROUP1/GROUP2', 'H5R_OBJECT', -1);
ref(:,3) = H5R.create(fileid, dsetnamei, 'H5R_OBJECT', -1);
ref(:,4) = H5R.create(fileid, 'MYTYPE', 'H5R_OBJECT', -1);

H5D.write(dsetr_id, 'H5T_STD_REF_OBJ', 'H5S_ALL', 'H5S_ALL',...
               'H5P_DEFAULT', ref);

% Close the dataset. 
H5D.close(dsetr_id);

% Reopen the dataset with object references and read references to the buffer.
dsetr_id = H5D.open( fileid, dsetnamer);
ref_out = H5D.read(dsetr_id, 'H5T_STD_REF_OBJ', 'H5S_ALL', 'H5S_ALL',...
                'H5P_DEFAULT');

% Dereference the third reference. We know that it is a dataset. On practice
% one should use H5Rget_object_type function to find out
% the type of an object the reference points to.
dset_id = H5R.dereference(dsetr_id, 'H5R_OBJECT', ref(:,3));

% Write data to the dataset.
H5D.write(dset_id, 'H5T_NATIVE_INT', 'H5S_ALL' , 'H5S_ALL', 'H5P_DEFAULT', data);

% Dereference the fourth reference. We know that it is a datatype. On practice
% one should use H5Rget_object_type function to find out
% the type of an object the reference points to.
type_id = H5R.dereference(dsetr_id, 'H5R_OBJECT', ref(:,4));

% Get datatype class and indicate success if it is of a FLOAT class.
class = H5T.get_class(type_id);
if H5ML.compare_values(class, 'H5T_FLOAT')
    status = true;
end
    
H5D.close(dset_id);
H5D.close(dsetr_id);
H5T.close(type_id);
H5F.close(fileid);