test/std/algorithms/alg.nonmodifying/alg.foreach/for_each_n.pass.cpp

//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// <algorithm>
// UNSUPPORTED: c++98, c++03, c++11, c++14

// template<class InputIterator, class Size, class Function>
//    InputIterator for_each_n(InputIterator first, Size n, Function f);


#include <algorithm>
#include <cassert>

#include "test_iterators.h"

struct for_each_test
{
    for_each_test(int c) : count(c) {}
    int count;
    void operator()(int& i) {++i; ++count;}
};

int main()
{
    typedef input_iterator<int*> Iter;
    int ia[] = {0, 1, 2, 3, 4, 5};
    const unsigned s = sizeof(ia)/sizeof(ia[0]);

    {
    auto f = for_each_test(0);
    Iter it = std::for_each_n(Iter(ia), 0, std::ref(f));
    assert(it == Iter(ia));
    assert(f.count == 0);    
    }

    {
    auto f = for_each_test(0);
    Iter it = std::for_each_n(Iter(ia), s, std::ref(f));
    
    assert(it == Iter(ia+s));
    assert(f.count == s);    
    for (unsigned i = 0; i < s; ++i)
        assert(ia[i] == static_cast<int>(i+1));
    }

    {
    auto f = for_each_test(0);
    Iter it = std::for_each_n(Iter(ia), 1, std::ref(f));
    
    assert(it == Iter(ia+1));
    assert(f.count == 1);    
    for (unsigned i = 0; i < 1; ++i)
        assert(ia[i] == static_cast<int>(i+2));
    }
}