hproselet/hprose_srv.hpp

#ifndef _HPROSE_SRV_HPP_
#define _HPROSE_SRV_HPP_

#include <unordered_map>
#include <vector>

#include "hprose_ed.hpp"
#include "hprose_types.hpp"

template<typename RET>
struct Invoker {
    template <typename OBJECT, typename HANDLER, typename... ARGS>
    bool operator() (OBJECT* objs, HANDLER&& handler, HproseWriter& w, ARGS&... args) const {
        return HproseValueHelper<RET>().ToWriterWithResultTag(handler(std::forward<ARGS&>(args)...), w);
    }
};

template<>
struct Invoker<void> {
    template <typename OBJECT, typename HANDLER, typename... ARGS>
    bool operator() (OBJECT* objs, HANDLER&& handler, HproseWriter& w, ARGS&... args) const {
        handler(std::forward<ARGS&>(args)...);
        return HproseValueHelperNull().ToWriterWithResultTag(w);
    }
};

template<typename RET>
struct InvokerObj {
    template <typename OBJECT, typename HANDLER, typename... ARGS>
    bool operator() (OBJECT* objs, HANDLER&& handler, HproseWriter& w, ARGS&... args) const {
        return HproseValueHelper<RET>().ToWriterWithResultTag((*objs.*handler)(std::forward<ARGS&>(args)...), w);
    }
};

template<>
struct InvokerObj<void> {
    template <typename OBJECT, typename HANDLER, typename... ARGS>
    bool operator() (OBJECT* objs, HANDLER&& handler, HproseWriter& w, ARGS&... args) const {
        (*objs.*handler)(std::forward<ARGS&>(args)...);
        return HproseValueHelperNull().ToWriterWithResultTag(w);
    }
};

template<typename T>
struct HandlerType {
    using class_type = void;
    using arg_helper = std::tuple<>;
    using arg_type = std::tuple<>;
    using invoke_type = void;
    static constexpr int32_t arg_count = 0;
};

template<typename RET, typename... ARGS>
struct HandlerType<std::function<RET(ARGS...)>> {
    using class_type = void;
    using arg_type = std::tuple<std::remove_const_t<std::remove_reference_t<ARGS>>...>;
    using invoke_type = Invoker<RET>;
    using call_type = std::function<RET(ARGS...)>;
    static constexpr int32_t arg_count = sizeof...(ARGS);
};

template<typename RET, typename CLASS, typename... ARGS>
struct HandlerType<RET(CLASS::*)(ARGS...)> {
    using class_type = CLASS;
    using arg_type = std::tuple<std::remove_const_t<std::remove_reference_t<ARGS>>...>;
    using invoke_type = InvokerObj<RET>;
    using call_type = RET(CLASS::*)(ARGS...);
    static constexpr int32_t arg_count = sizeof...(ARGS);
};

template<typename RET, typename CLASS, typename... ARGS>
struct HandlerType<RET(CLASS::*)(ARGS...) const> {
    using class_type = CLASS;
    using arg_type = std::tuple<std::remove_const_t<std::remove_reference_t<ARGS>>...>;
    using invoke_type = InvokerObj<RET>;
    using call_type = RET(CLASS::*)(ARGS...) const;
    static constexpr int32_t arg_count = sizeof...(ARGS);
};

template<typename OBJECT>
struct HproseInvoker {
    virtual void Call(OBJECT* obj, HproseReader& r, HproseWriter& w) = 0;
    virtual ~HproseInvoker() {};
};

template<typename HANDLER>
class HProseCallType : public HproseInvoker<typename HandlerType<typename FunctionType<HANDLER>::type>::class_type> {
public:
    using handler_type = HandlerType<typename FunctionType<HANDLER>::type>;
    using args_type = typename handler_type::arg_type;

    HProseCallType(HANDLER h, const std::string& name) : handler(h), method(name) {}

    virtual void Call(typename handler_type::class_type* obj, HproseReader& r, HproseWriter& w) {
        args_type args;
        if(r.CheckTag(Tags::List, false))
            args = HproseValueHelper<args_type>().FromReader(r);
        bool ref = r.CheckTag(Tags::True, true);
        bool has_error = CallImpl(obj, args, w, std::make_index_sequence<handler_type::arg_count>{});
        if(ref && handler_type::arg_count > 0 && !has_error) {
            w.WriteTag(Tags::Argument);
            HproseValueHelper<args_type>().ToWriter(args, w);
        }
    }

    template<size_t... I>
    bool CallImpl(typename handler_type::class_type* obj, args_type& args, HproseWriter& w, std::index_sequence<I...>) {
        return typename handler_type::invoke_type()(obj, handler, w, std::get<I>(args)...);
    }

protected:
    HANDLER handler;
    std::string method;
};

template<typename F>
std::unique_ptr<HProseCallType<F>> MakeHproseCallType(F f, const std::string& name) {
    return std::unique_ptr<HProseCallType<F>>(new HProseCallType<F>(f, name));
}

template<typename OBJECT>
class HproseServer {
public:
    template<typename HANDLER>
    void Register(const char* name, HANDLER func) {
        auto invoker = std::unique_ptr<HproseInvoker<OBJECT>>(MakeHproseCallType(func, name));
        rpc_calls[name] = std::move(invoker);
    }

    void HandleRequests(OBJECT* sess, HproseReader& reader, HproseWriter& writer) {
        auto tag = reader.ReadTag();
        while(tag == Tags::Call) {
            auto method = HproseValueHelperString().FromReader(reader);
            auto iter = rpc_calls.find(method);
            if(iter == rpc_calls.end()) {
                HproseError err(std::move(std::string("Error: \"").append(method).append("\" not found.")));
                HproseValueHelperError().ToWriterWithResultTag(err, writer);
                reader.SkipValue();
                reader.SkipValue();
                tag = reader.ReadTag();
                continue;
            }
            iter->second->Call(sess, reader, writer);
            tag = reader.ReadTag();
        }
    }
    
    template<typename SVC>
    void UseConnector(SVC& svc) {
        svc.SetObjectAllocator([this]() -> std::shared_ptr<OBJECT> {
            if(obj_allocator)
                return obj_allocator();
            return nullptr;
        });
        svc.SetPacketHandler([this](OBJECT* obj, HproseReader& reader, HproseWriter& writer) {
            this->HandleRequests(obj, reader, writer);
        });
        svc.Start();
    }

    void SetObjectAllocator(const std::function<std::shared_ptr<OBJECT>()>& cb) { obj_allocator = cb; }

protected:
    std::function<std::shared_ptr<OBJECT>()> obj_allocator;
    std::unordered_map<std::string, std::unique_ptr<HproseInvoker<OBJECT>>> rpc_calls;
};

#endif