//#include <libdj/istream.h>
#include <istream>
#include <stdexcept>

namespace dj {
    inline
    void read_istream_into_string(std::istream& inp, std::string &outp) {
        // Requires inp.seekg(), and inp.tellg()
        if (!inp.good()) {
            throw std::invalid_argument("read_istream_into_string: istream argument 'inp.good()' returned false.");
        }
        if (!inp.seekg(0, std::ios::end)) {
            throw std::runtime_error("read_istream_into_string: istream  inp.seekg(0 std::ios::end) failed");
        }
        outp.reserve(inp.tellg()); // Throws bad_alloc and length_error
        if (!inp.seekg(0, std::ios::beg)) {
            throw std::runtime_error("read_istream_into_string: istream inp.seekg(0, std::ios::beg) failed");
        }
        outp.assign((std::istreambuf_iterator<char>(inp)),
            std::istreambuf_iterator<char>());
    }
}

#include <fstream>

int main() {
    std::ifstream inp("junk.txt");
    std::string buffer;
    dj::read_istream_into_string(inp, buffer);
    std::cout << buffer << std::endl;
}