//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// <unordered_map>

// template <class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>,
//           class Alloc = allocator<pair<const Key, T>>>
// class unordered_multimap

// iterator erase(const_iterator p)

#include <unordered_map>
#include <string>
#include <cassert>
#include <cstddef>

#include "min_allocator.h"

struct TemplateConstructor
{
    template<typename T>
    TemplateConstructor (const T&) {}
};

bool operator==(const TemplateConstructor&, const TemplateConstructor&) { return false; }
struct Hash { size_t operator() (const TemplateConstructor &) const { return 0; } };

int main(int, char**)
{
    {
        typedef std::unordered_multimap<int, std::string> C;
        typedef std::pair<int, std::string> P;
        P a[] =
        {
            P(1, "one"),
            P(2, "two"),
            P(3, "three"),
            P(4, "four"),
            P(1, "four"),
            P(2, "four"),
        };
        C c(a, a + sizeof(a)/sizeof(a[0]));
        C::const_iterator i = c.find(2);
        C::const_iterator i_next = i;
        ++i_next;
        C::iterator j = c.erase(i);
        assert(j == i_next);

        assert(c.size() == 5);
        typedef std::pair<C::const_iterator, C::const_iterator> Eq;
        Eq eq = c.equal_range(1);
        assert(std::distance(eq.first, eq.second) == 2);
        C::const_iterator k = eq.first;
        assert(k->first == 1);
        assert(k->second == "one");
        ++k;
        assert(k->first == 1);
        assert(k->second == "four");
        eq = c.equal_range(2);
        assert(std::distance(eq.first, eq.second) == 1);
        k = eq.first;
        assert(k->first == 2);
        assert(k->second == "four");
        eq = c.equal_range(3);
        assert(std::distance(eq.first, eq.second) == 1);
        k = eq.first;
        assert(k->first == 3);
        assert(k->second == "three");
        eq = c.equal_range(4);
        assert(std::distance(eq.first, eq.second) == 1);
        k = eq.first;
        assert(k->first == 4);
        assert(k->second == "four");
        assert(static_cast<std::size_t>(std::distance(c.begin(), c.end())) == c.size());
        assert(static_cast<std::size_t>(std::distance(c.cbegin(), c.cend())) == c.size());
    }
#if TEST_STD_VER >= 11
    {
        typedef std::unordered_multimap<int, std::string, std::hash<int>, std::equal_to<int>,
                            min_allocator<std::pair<const int, std::string>>> C;
        typedef std::pair<int, std::string> P;
        P a[] =
        {
            P(1, "one"),
            P(2, "two"),
            P(3, "three"),
            P(4, "four"),
            P(1, "four"),
            P(2, "four"),
        };
        C c(a, a + sizeof(a)/sizeof(a[0]));
        C::const_iterator i = c.find(2);
        C::const_iterator i_next = i;
        ++i_next;
        C::iterator j = c.erase(i);
        assert(j == i_next);

        assert(c.size() == 5);
        typedef std::pair<C::const_iterator, C::const_iterator> Eq;
        Eq eq = c.equal_range(1);
        assert(std::distance(eq.first, eq.second) == 2);
        C::const_iterator k = eq.first;
        assert(k->first == 1);
        assert(k->second == "one");
        ++k;
        assert(k->first == 1);
        assert(k->second == "four");
        eq = c.equal_range(2);
        assert(std::distance(eq.first, eq.second) == 1);
        k = eq.first;
        assert(k->first == 2);
        assert(k->second == "four");
        eq = c.equal_range(3);
        assert(std::distance(eq.first, eq.second) == 1);
        k = eq.first;
        assert(k->first == 3);
        assert(k->second == "three");
        eq = c.equal_range(4);
        assert(std::distance(eq.first, eq.second) == 1);
        k = eq.first;
        assert(k->first == 4);
        assert(k->second == "four");
        assert(static_cast<std::size_t>(std::distance(c.begin(), c.end())) == c.size());
        assert(static_cast<std::size_t>(std::distance(c.cbegin(), c.cend())) == c.size());
    }
#endif
#if TEST_STD_VER >= 14
    {
    //  This is LWG #2059
        typedef TemplateConstructor T;
        typedef std::unordered_multimap<T, int, Hash> C;
        typedef C::iterator I;

        C m;
        T a{0};
        I it = m.find(a);
        if (it != m.end())
            m.erase(it);
    }
#endif

  return 0;
}