scan_tests.cpp

#include <numeric>
#include <array>
#include <vector>
#include <string>
#include <cassert>

int main()
{
    std::array<std::string, 3> ia{{ "a", "b", "c" }};

    std::vector<std::string> v0;
    std::exclusive_scan(ia.begin(), ia.end(), std::back_inserter(v0), std::string("_"), std::plus<>());
    // 1st sum: *(output)              = init;
    // 2nd sum: *(output+1)            = init + *first;
    // 3rd sum: *(output+2)            = init + *first + *(first+1);
    // ...
    // Nth sum: *(output+(last-first)) = init + *first + *(first+1) + ... + *(first+(last-first)-1);
    assert(v0[0] == "_");
    assert(v0[1] == "_a");
    assert(v0[2] == "_ab");

    std::vector<std::string> v1;
    std::inclusive_scan(ia.begin(), ia.end(), std::back_inserter(v1), std::plus<>(), std::string("_"));
    // 1st sum: *(output)              = init + *first;
    // 2nd sum: *(output+1)            = init + *first + *(first+1);
    // 3rd sum: *(output+2)            = init + *first + *(first+1) + *(first+2);
    // ...
    // Nth sum: *(output+(last-first)) = init + *first + *(first+1) + ... + *(first+(last-first));
    assert(v0[0] == "_a");
    assert(v0[1] == "_ab");
    assert(v0[2] == "_abc");

    std::vector<std::string> v2;
    std::inclusive_scan(ia.begin(), ia.end(), std::back_inserter(v2), std::plus<>());
    // 1st sum: *(output)              = *first;
    // 2nd sum: *(output+1)            = *first + *(first+1);
    // 3rd sum: *(output+2)            = *first + *(first+1) + *(first+2);
    // ...
    // Nth sum: *(output+(last-first)) = *first + *(first+1) + ... + *(first+(last-first));
    assert(v0[0] == "a");
    assert(v0[1] == "ab");
    assert(v0[2] == "abc");

    std::vector<std::string> v3;
    std::exclusive_scan(ia.begin(), ia.begin(), std::back_inserter(v3), std::string("_"), std::plus<>());
    assert(v3.empty());

    std::vector<std::string> v4;
    std::inclusive_scan(ia.begin(), ia.begin(), std::back_inserter(v4), std::plus<>(), std::string("_"));
    assert(v4.empty());

    std::vector<std::string> v5;
    std::inclusive_scan(ia.begin(), ia.begin(), std::back_inserter(v5), std::plus<>());
    assert(v5.empty());
}