inline typename boost::enable_if<boost::is_same<T, std::string>, T>::type
read_attribute(H5::H5Object const& object, std::string const& name)
{
H5::Attribute attr;
try {
H5XX_NO_AUTO_PRINT(H5::AttributeIException);
attr = object.openAttribute(name);
}
catch (H5::AttributeIException const&) {
throw;
}
if (!has_scalar_space(attr)) {
throw H5::AttributeIException("H5::attribute::as", "incompatible dataspace");
}
H5::DataType tid = attr.getDataType();
std::string value;
if (!tid.isVariableStr()) {
// read fixed-size string, allocate space in advance and let the HDF5
// library take care about NULLTERM and NULLPAD strings
value.resize(tid.getSize(), std::string::value_type());
attr.read(tid, &*value.begin());
}
else {
// read variable-length string, memory will be allocated by HDF5 C
// library and must be freed by us
char *c_str;
if (H5Aread(attr.getId(), tid.getId(), &c_str) < 0) {
throw H5::AttributeIException("Attribute::read", "H5Aread failed");
}
value = c_str; // copy '\0'-terminated string
free(c_str);
}
return value;
}
inline typename boost::enable_if<boost::mpl::and_<
is_vector<T>
, boost::is_same<typename T::value_type, std::string>
>, T>::type
read_attribute(H5::H5Object const& object, std::string const& name)
{
H5::Attribute attr;
try {
H5XX_NO_AUTO_PRINT(H5::AttributeIException);
attr = object.openAttribute(name);
}
catch (H5::AttributeIException const&) {
throw;
}
H5::DataSpace ds(attr.getSpace());
if (!ds.isSimple()) {
throw H5::AttributeIException("H5::attribute::as", "incompatible dataspace");
}
size_t size = ds.getSimpleExtentNpoints();
H5::DataType tid = attr.getDataType();
if (tid.isVariableStr()) {
throw error("reading non-scalar attribute of variable-length strings not supported");
}
size_t str_len = tid.getSize();
// read to contiguous buffer and copy to std::vector
std::vector<char> buffer(str_len * size);
attr.read(tid, &*buffer.begin());
T value;
value.reserve(size);
char const* s = buffer.data();
for (size_t i = 0; i < size; ++i, s += str_len) {
size_t len = strnlen(s, str_len); // strings of str_len size are not '\0'-terminated
value.push_back(std::string(s, len)); // copy len bytes from buffer
}
return value;
}
