ostream_sink.hpp

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#ifndef EAGINE_SERIALIZE_OSTREAM_SINK_HPP
#define EAGINE_SERIALIZE_OSTREAM_SINK_HPP
 
#include "data_sink.hpp"
#include <limits>
#include <ostream>
#include <sstream>
#include <stack>
 
namespace eagine {
//------------------------------------------------------------------------------
class ostream_data_sink : public serializer_data_sink {
public:
    ostream_data_sink(std::ostream& out) noexcept
      : _out{out} {}
 
    auto remaining_size() -> span_size_t final {
        return std::numeric_limits<span_size_t>::max();
    }
 
    using serializer_data_sink::write;
 
    auto write(memory::const_block blk) -> serialization_errors final {
        write_to_stream(current(), blk);
        if(current().eof()) {
            return {serialization_error_code::too_much_data};
        }
        if(!current().good()) {
            return {serialization_error_code::data_sink_error};
        }
        return {};
    }
 
    auto begin_work() -> transaction_handle final {
        _subs.emplace();
        return transaction_handle(_subs.size());
    }
 
    void commit(transaction_handle th) final {
        EAGINE_ASSERT(th == transaction_handle(_subs.size()));
        EAGINE_MAYBE_UNUSED(th);
        std::stringstream top{std::move(_subs.top())};
        _subs.pop();
        current() << top.rdbuf();
    }
 
    void rollback(transaction_handle th) final {
        EAGINE_ASSERT(th == transaction_handle(_subs.size()));
        EAGINE_MAYBE_UNUSED(th);
        _subs.pop();
    }
 
    auto finalize() -> serialization_errors final {
        return {};
    }
 
private:
    auto current() noexcept -> std::ostream& {
        if(_subs.empty()) {
            return _out;
        }
        return _subs.top();
    }
 
    std::ostream& _out;
    std::stack<std::stringstream> _subs;
};
//------------------------------------------------------------------------------
} // namespace eagine
 
#endif // EAGINE_SERIALIZE_OSTREAM_SINK_HPP