相关疑难解决方法(0)

有一个很好的C++解决方案(实际上是2个解决方案:递归和非递归),是一个整数向量向量的笛卡尔积.出于说明/简单的目的,让我们只关注非递归版本.

我的问题是,如何用模板推广这个代码来获取std::tuple看起来像这样的同类向量:

{{2,5,9},{"foo","bar"}}

并生成一个齐次的矢量 tuple

{{2,"foo"},{2,"bar"},{5,"foo"},{5,"bar"},{9,"foo"},{9,"bar"}}

如果它让生活更容易,让我们假设输入中的内部向量都是同质的.所以不允许这样的输入: {{5,"baz"}{'c',-2}}

编辑将输入从锯齿状矢量更改为元组

我想为几个可能类的几种组合编写基准代码.如果我自己编写每个组合,它就变成了一个难以维护的混乱.因此,我正在寻找一种通过模板自动组合每种类型的方法,类似于以下伪代码:

for (typename HashFuction : Sha256, Sha512, Sa512_256, Sha3_256, Sha3_512) {
   for (typename KeyingWrapper : TwoPassKeyedHash, OnePassKeyedHash, PlainHash) {
      for (typename InstantiatedGetLeaf: GetLeaf<8>, GetLeaf<1024>) {
         for (typename algorithm : algA, algB, algC) {
            runAndTime<HashFunction,KeyingWrapper,
                       InstantiatedGetLeaf,algorithm>(someArgs);
         }
       }
    }
 }

哪里Sha256,......,TwoPassKeyedHash......是类型.

我正在寻找的代码应该在功能上等同于以下内容:

runAndTime<Sha256,TwoPassKeyedHash,GetLeaf<8>,algA>(someArgs);
runAndTime<Sha256,TwoPassKeyedHash,GetLeaf<8>,algB>(someArgs);
runAndTime<Sha256,TwoPassKeyedHash,GetLeaf<8>,algC>(someArgs);

runAndTime<Sha256,TwoPassKeyedHash,GetLeaf<1024>,algA>(someArgs);
runAndTime<Sha256,TwoPassKeyedHash,GetLeaf<1024>,algB>(someArgs);
runAndTime<Sha256,TwoPassKeyedHash,GetLeaf<1024>,algC>(someArgs);

runAndTime<Sha256,OnePassKeyedHash,GetLeaf<8>,algA>(someArgs);
runAndTime<Sha256,OnePassKeyedHash,GetLeaf<8>,algB>(someArgs);
runAndTime<Sha256,OnePassKeyedHash,GetLeaf<8>,algC>(someArgs);

// And 99 further lines…

在Peregring-lk的帮助下,我已经走到了尽头

#include <iostream>

template<typename Aux_type>
void test_helper()
{}

template<typename Aux_type, typename Head, typename... Tail>
void test_helper() {
   std::cout << Head::i;
   test_helper<Aux_type, …