/**

?* 北太天元的插件開發(fā)示例，這個(gè)還不是完整的，我這幾天的視頻的想法是

?* 每次介紹很少的幾個(gè)知識點(diǎn),面向的對象是對c++11之后的特性不熟悉的同學(xué)。

?* 這是和前一個(gè)視頻相比增加了if constexpr 實(shí)現(xiàn)編譯期計(jì)算的功能。

?*/

#include <cstdlib>

#include <iostream>

#include <typeinfo>

#include <utility>

#include <array>

#include <map>

#include <vector>

#include "bex/bex.hpp"

namespace ParseParams {

???template <class _T>

??????class FunTrait;

???template <typename R, typename... Args>

??????class FunTrait<R(Args...)>{

?????????public:

????????????static constexpr size_t n_args = sizeof...(Args);

????????????static constexpr const std::array<const std::type_info *, n_args> infos = {&typeid(Args)...};

?????????public:

?????????int required_params;

?????????std::array<void *, n_args> passed_args_ptr;

?????????//變量類型函數(shù)句柄, 變量名是decorated_func

?????????R(*decorated_func)

????????????(Args...);

?????????public:

?????????FunTrait(R (*func)(Args...), int num_required = 0){

????????????decorated_func = func;

??????????required_params = num_required;

?????????}

?????????template <size_t... I>

?????????R eval_impl(std::index_sequence<I...>){

????????????std::cout<<"必須的參數(shù)個(gè)數(shù)是 = " << required_params << std::endl;

????????????return decorated_func((Args)passed_args_ptr[I]...);

?????????}

?????????R eval(){

????????????return eval_impl(std::make_index_sequence<n_args>());

?????????}

?????????int check_in_args_type(int nrhs, const bxArray * prhs[]){

????????????for(size_t i= 0; i< n_args; i++){

???????????????if(infos[i]->name() == typeid(const double *).name()){

??????????????????if(!bxIsDouble(prhs[i])){

?????????????????????bxPrintf("第%d輸入?yún)?shù)必須是double類型",i);

?????????????????????return 1;

??????????????????}

??????????????????passed_args_ptr[i] = (void *)(bxGetDoubles(prhs[i]));

???????????????}???

???????????????else if(infos[i]->name() == typeid(const int32_t *).name()){

??????????????????if(!bxIsInt32(prhs[i])){

?????????????????????bxPrintf("第%d輸入?yún)?shù)必須是int32類型",i);

?????????????????????return 1;

??????????????????}

??????????????????passed_args_ptr[i] = (void *)(bxGetInt32s(prhs[i]));

???????????????}???

???????????????else if(infos[i]->name() == typeid(const int64_t *).name()){

??????????????????if(!bxIsInt64(prhs[i])){

?????????????????????bxPrintf("第%d輸入?yún)?shù)必須是int64類型",i);

?????????????????????return 1;

??????????????????}

??????????????????passed_args_ptr[i] = (void *)(bxGetInt64s(prhs[i]));

???????????????}???

???????????????else if(infos[i]->name() == typeid(const std::string *).name()){

??????????????????if(!bxIsString(prhs[i])){

?????????????????????bxPrintf("第%d輸入?yún)?shù)必須是string類型",i);

?????????????????????return 1;

??????????????????}

??????????????????passed_args_ptr[i] = (void *)(new std::string(bxGetStringDataPr(prhs[i])));

??????????????????/**

??????????????????* 這兒new 的東西，沒有delete，會有內(nèi)存泄漏

??????????????????*/

???????????????}

???????????????else {

?????????????????????bxPrintf("第%d輸入?yún)?shù)類型不對",i);

?????????????????????return 1;

???????????????}

????????????}

????????????return 0;

?????????}

?????????void return_to_bxArray(R result, int nlhs, bxArray *plhs[]){

????????????if(nlhs <= 0 ) return;

????????????if constexpr (std::is_same<char, R>::value){

???????????????char tmp[2] ={result, '\0'};

???????????????plhs[0] = bxCreateString(tmp);???

????????????}???

????????????else if constexpr (std::is_same<int32_t,R>::value){

???????????????plhs[0] = bxCreateInt32Scalar(result);

????????????}

????????????else if constexpr (std::is_same<double,R>::value){

???????????????plhs[0] = bxCreateDoubleMatrix(1,1,bxREAL);

???????????????double * ptr = bxGetDoubles(plhs[0]);

???????????????*ptr = result;

????????????}???

????????????else if constexpr (std::is_same<std::string,R>::value){

???????????????plhs[0] = bxCreateString(result.c_str());

????????????}

?????????}

??????};

}

char h(const int *j , const std::string?*str ){

???std::cout<<" *j = "<<*j << std::endl;

???std::cout<<" *str = "<<*str << std::endl;

???std::cout<<" (*str)[*j] = "<<(*str)[*j]<< std::endl;

???return (*str)[*j];

}

void cmd_h(int nlhs, bxArray *plhs[], int nrhs, const bxArray *prhs[]) {

???ParseParams::FunTrait<decltype(h)> q(h,0);

???if(nrhs < q.n_args ){

??????bxPrintf("輸入?yún)?shù)%d < %d", nrhs, q.n_args);

??????return;

???}???

???if(0 != q.check_in_args_type(nrhs, prhs)){

??????bxPrintf("輸入?yún)?shù)賦值出錯\n");

??????return;

???}

???auto result = q.eval();

???q.return_to_bxArray(result, nlhs, plhs);

}

static bexfun_info_t flist[] = {

?{"cmdd_h", cmd_h, nullptr},

?{"", nullptr, nullptr},

};

bexfun_info_t *bxPluginFunctions() {

?return flist;

}