language: C++11 (gcc-4.7.2)
date: 190 days 13 hours ago
link:
visibility: public 
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#include <iostream>
#include <type_traits>
#include <vector>
#include <iostream>
#include <set>
 
template<typename T, typename Iterator, typename=void>
struct is_iterator_of_type: std::false_type {};
 
template<typename T, typename Iterator>
struct is_iterator_of_type<
    T,
        Iterator,
        typename std::enable_if<
                std::is_same<
                        T,
                        typename std::iterator_traits< Iterator >::value_type
                >::value
        >::type
>: std::true_type {};
 
void test1() {
  std::cout << is_iterator_of_type<int, std::vector<int>::iterator>::value << "\n";
}
template<typename T, typename Container>
auto foo(Container const&) -> typename std::enable_if< is_iterator_of_type<T, typename Container::iterator>::value >::type
{
        std::cout << "Container of int\n";
}
template<typename T>
void foo(...)
{
        std::cout << "No match\n";
}
void test2() {
  std::vector<int> test;
        foo<int>(test);
        foo<int>(test.begin());
        foo<int>(std::set<int>());
}
template<typename Container>
auto operator<<( std::ostream& stream, Container const& c ) ->
        typename std::enable_if< is_iterator_of_type<int, typename Container::iterator>::value, std::ostream& >::type
{
        stream << "int container\n";
}
void test3() {
        std::vector<int> test;
        std::cout << test;
        std::set<int> bar;
        std::cout << bar;
}
template<typename Container>
auto operator<<( std::ostream& stream, Container const& c ) ->
        typename std::enable_if< is_iterator_of_type<double, typename Container::iterator>::value, std::ostream& >::type
{
        stream << "double container\n";
}
void test4() {
        std::vector<int> test;
        std::cout << test;
        std::set<int> bar;
        std::cout << bar;
        std::vector<double> dtest;
        std::cout << dtest;
}
void test5() {
        std::vector<bool> test;
        // does not compile (naturall):
        // std::cout << test;
}
template<typename Container>
auto operator<<( std::ostream& stream, Container const& c ) ->
        typename std::enable_if< is_iterator_of_type<bool, typename Container::iterator>::value, std::ostream& >::type
{
        stream << "bool container\n";
}
void test6() {
        std::vector<bool> test;
        // now compiles:
        std::cout << test;
}
int main() {
        test1();
        test2();
        test3();
        test4();
        test5();
        test6();
}