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Copy pathmulti_parameter_function.cc
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204 lines (175 loc) · 6.19 KB
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/*
* 用户可以传入带有以下类型的任意数量的参数
* int
* double
* string
* ...有限个且已知都有哪些类型
* 如何在底层用相同类型的std::function对象保存这些函数对象
*
* 方法：对用户传入的函数对象再进行一层包装
*/
#include <vector>
#include <tuple>
#include <memory>
#include <functional>
template <typename R, typename... Args>
struct function_traits {};
template <typename R, typename... Args>
struct function_traits<R(Args...)> {
static constexpr std::size_t artiy = sizeof...(Args);
using return_type = R;
template <std::size_t N>
using arg = std::tuple_element_t<N, std::tuple<Args...>>;
};
template <typename R, typename... Args>
struct function_traits<R(*)(Args...)> {
static constexpr std::size_t artiy = sizeof...(Args);
using return_type = R;
template <std::size_t N>
using arg = std::tuple_element_t<N, std::tuple<Args...>>;
};
/* 假设用户只能传int64_t, uint64_t, double, string四种类型的参数，且类型的顺序无要求，个数无要求 */
struct routing_params
{
std::vector<int64_t> int_params;
std::vector<uint64_t> uint_params;
std::vector<double> double_params;
std::vector<std::string> string_params;
template <typename T>
T get(unsigned) const;
};
template <>
inline int64_t routing_params::get<int64_t>(unsigned index) const {
return int_params[index];
}
template <>
inline uint64_t routing_params::get<uint64_t>(unsigned index) const {
return uint_params[index];
}
template <>
inline double routing_params::get<double>(unsigned index) const {
return double_params[index];
}
template <>
inline std::string routing_params::get<std::string>(unsigned index) const {
return string_params[index];
}
template <typename H>
struct call_params
{
H& handler;
const routing_params& params;
};
template <typename... T>
struct S
{
template <typename U>
using push_front = S<U, T...>;
template <typename U>
using push_back = S<T..., U>;
};
template <typename Type, int Pos>
struct call_pair
{
using type = Type;
static constexpr int pos = Pos;
};
template <typename F, int Nint, int Nuint, int Ndouble, int Nstring, typename S1, typename S2>
struct call { };
template <typename F, int Nint, int Nuint, int Ndouble, int Nstring, typename... Args1, typename... Args2>
struct call<F, Nint, Nuint, Ndouble, Nstring, S<int64_t, Args1...>, S<Args2...>>
{
void operator()(F cparams) {
using pushed = typename S<Args2...>::template push_back<call_pair<int64_t, Nint>>;
call<F, Nint + 1, Nuint, Ndouble, Nstring, S<Args1...>, pushed>()(cparams);
}
};
template <typename F, int Nint, int Nuint, int Ndouble, int Nstring, typename... Args1, typename... Args2>
struct call<F, Nint, Nuint, Ndouble, Nstring, S<uint64_t, Args1...>, S<Args2...>>
{
void operator()(F cparams) {
using pushed = typename S<Args2...>::template push_back<call_pair<uint64_t, Nuint>>;
call<F, Nint, Nuint + 1, Ndouble, Nstring, S<Args1...>, pushed>()(cparams);
}
};
template <typename F, int Nint, int Nuint, int Ndouble, int Nstring, typename... Args1, typename... Args2>
struct call<F, Nint, Nuint, Ndouble, Nstring, S<double, Args1...>, S<Args2...>>
{
void operator()(F cparams) {
using pushed = typename S<Args2...>::template push_back<call_pair<double, Ndouble>>;
call<F, Nint, Nuint, Ndouble + 1, Nstring, S<Args1...>, pushed>()(cparams);
}
};
template <typename F, int Nint, int Nuint, int Ndouble, int Nstring, typename... Args1, typename... Args2>
struct call<F, Nint, Nuint, Ndouble, Nstring, S<std::string, Args1...>, S<Args2...>>
{
void operator()(F cparams) {
using pushed = typename S<Args2...>::template push_back<call_pair<std::string, Nstring>>;
call<F, Nint, Nuint, Ndouble, Nstring + 1, S<Args1...>, pushed>()(cparams);
}
};
template <typename F, int Nint, int Nuint, int Ndouble, int Nstring, typename... Args1>
struct call<F, Nint, Nuint, Ndouble, Nstring, S<>, S<Args1...>>
{
void operator()(F cparams) {
cparams.handler(cparams.params.template get<typename Args1::type>(Args1::pos)...);
}
};
template <typename Func, typename... ArgsWarpper>
struct function_warpper
{
template <typename... Args>
void set_(Func f) {
handler_ = [f = std::move(f)](Args... args){
std::forward<Func>(f)(args...);
};
}
void operator()(const routing_params& params) {
call<call_params<decltype(handler_)>, 0, 0, 0, 0, S<ArgsWarpper...>, S<>>()(call_params<decltype(handler_)>{handler_, params});
}
std::function<void(ArgsWarpper...)> handler_;
};
class DynamicRule
{
public:
DynamicRule(std::string&& rule)
: rule_(std::forward<std::string>(rule))
{ }
template<typename Func>
void operator()(Func f) {
/* 首先需要知道用户传入的函数对象的类型是什么，也就是需要解析出
* 返回值类型，每个参数类型，参数个数 */
using function_t = function_traits<Func>;
erased_handler_ = warp(std::move(f), std::make_index_sequence<function_t::artiy>{});
}
template <typename Func, std::size_t... Indices>
std::function<void(routing_params&)> warp(Func f, std::index_sequence<Indices...>) {
using function_t = function_traits<Func>;
auto ret = function_warpper<Func, typename function_t::template arg<Indices>...>{};
ret.template set_<function_t::template arg<Indices>...>(std::move(f));
return ret;
}
private:
std::string rule_;
std::function<void(routing_params&)> erased_handler_;
};
class Router
{
public:
DynamicRule& new_rule_dynamic(std::string&& rule) {
auto dynamic_rule = new DynamicRule(std::forward<std::string>(rule));
all_rules_.emplace_back(dynamic_rule);
return *dynamic_rule;
}
private:
std::vector<std::unique_ptr<DynamicRule>> all_rules_;
};
class Server
{
public:
void routing_dynamic(std::string&& rule) {
router_.new_rule_dynamic(std::forward<std::string>(rule));
}
private:
Router router_;
};