read_scalar_string.hpp

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#ifndef RITSUKO_HDF5_READ_SCALAR_STRING_HPP
#define RITSUKO_HDF5_READ_SCALAR_STRING_HPP
 
#include "H5Cpp.h"
 
#include <string>
#include <vector>
#include <stdexcept>
#include <cassert>
 
#include "get_name.hpp"
#include "strnlen.hpp"
#include "ReclaimVlsMemory.hpp"
 
namespace ritsuko {
 
namespace hdf5 {
 
inline std::string read_scalar_string(const H5::DataSet& data) {
    const auto& dtype = data.getDataType();
    assert(dtype.getClass() == H5T_STRING);
    assert(data.getSpace().getSimpleExtentNdims() == 0);
 
    if (dtype.isVariableStr()) {
        const auto& dspace = data.getSpace();
        const auto& plist = H5::DSetMemXferPropList::DEFAULT;
        char* vptr;
        data.read(&vptr, dtype);
        [[maybe_unused]] ReclaimVlsMemory deletor(&dtype, &dspace, &plist, &vptr);
        if (vptr == NULL) {
            throw std::runtime_error("detected a NULL pointer for a variable length string in '" + get_name(data) + "'");
        }
        std::string output(vptr);
        return output;
 
    } else {
        const auto fixed_length = dtype.getSize();
        auto buffer = sanisizer::create<std::vector<char> >(fixed_length);
        data.read(buffer.data(), dtype);
        return std::string(buffer.begin(), buffer.begin() + strnlen(buffer.data(), fixed_length));
    }
}
 
inline std::string read_scalar_string(const H5::Attribute& attr) {
    const auto& dtype = attr.getDataType();
    assert(dtype.getClass() == H5T_STRING);
    assert(attr.getSpace().getSimpleExtentNdims() == 0);
 
    // Unfortunately, we can't just do 'std::string output; attr.read(dtype, output);', 
    // as we need to catch NULL pointers in the variable case.
 
    if (dtype.isVariableStr()) {
        const auto& dspace = attr.getSpace();
        const auto& plist = H5::DSetMemXferPropList::DEFAULT; // yes, even H5Aread uses H5P_DATASET_XFER_DEFAULT.
        char* buffer = NULL;
        attr.read(dtype, &buffer);
        [[maybe_unused]] ReclaimVlsMemory deletor(&dtype, &dspace, &plist, &buffer);
        if (buffer == NULL) {
            throw std::runtime_error("detected a NULL pointer for a variable length string attribute");
        }
        return std::string(buffer);
 
    } else {
        const auto len = dtype.getSize();
        auto buffer = sanisizer::create<std::vector<char> >(len);
        attr.read(dtype, buffer.data());
        return std::string(buffer.begin(), buffer.begin() + strnlen(buffer.data(), len));
    }
}
 
}
 
}
 
#endif