IstreamReader.hpp

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#ifndef BYTEME_ISTREAM_READER_HPP
#define BYTEME_ISTREAM_READER_HPP
 
#include <vector>
#include <stdexcept>
#include <memory>
#include <cstddef>
 
#include "Reader.hpp"
#include "check_buffer_size.hpp"
 
namespace byteme {
 
struct IstreamReaderOptions {
    std::size_t buffer_size = 65536;
};
 
template<class Pointer_>
class IstreamReader final : public Reader {
public:
    IstreamReader(Pointer_ input, const IstreamReaderOptions& options) : 
        my_input(std::move(input)),
        my_buffer(
            check_buffer_size<std::streamsize>( // for istream::read().
                check_buffer_size(options.buffer_size)
            )
        )
    {}
 
public:
    bool load() {
        if (!my_okay) {
            return false;
        }
 
        my_input->read(reinterpret_cast<char*>(my_buffer.data()), my_buffer.size());
        my_read = my_input->gcount();
 
        if (my_read < my_buffer.size()) {
            if (my_input->eof()) {
                my_okay = false;
            } else {
                throw std::runtime_error("failed to finish reading the input stream");
            }
        }
 
        return true;
    }
 
    const unsigned char* buffer() const {
        return my_buffer.data();
    }
 
    std::size_t available() const {
        return my_read;
    }
 
private:
    Pointer_ my_input;
    std::vector<unsigned char> my_buffer;
    std::size_t my_read = 0;
    bool my_okay = true;
};
 
}
 
#endif