diff --git a/README.md b/README.md
index 4ce8409..e6a1336 100644
--- a/README.md
+++ b/README.md
@@ -25,10 +25,11 @@
 
 ## Installation
 
-[flat.hpp][flat] is a single header library. All you need to do is copy the header file into your project and include this file:
+[flat.hpp][flat] is a header only library. All you need to do is copy the header files (`flat_set.hpp` and `flat_map.hpp`) into your project and include them:
 
 ```cpp
-#include "flat.hpp"
+#include "flat_set.hpp" // for flat_set<K>
+#include "flat_map.hpp" // for flat_map<K,V>
 ```
 
 ## API
diff --git a/flat_map.hpp b/flat_map.hpp
index 8e03418..b117b2a 100644
--- a/flat_map.hpp
+++ b/flat_map.hpp
@@ -9,17 +9,40 @@
 #include <vector>
 #include <memory>
 #include <utility>
+#include <iterator>
+#include <algorithm>
 #include <functional>
 #include <type_traits>
+#include <initializer_list>
 
 namespace flat_hpp
 {
     template < typename Key
              , typename Value
              , typename Compare = std::less<Key>
-             , typename Allocator = std::allocator<std::pair<const Key, Value>> >
+             , typename Allocator = std::allocator<std::pair<Key, Value>> >
     class flat_map final {
-        using data_type = std::vector<std::pair<const Key, Value>, Allocator>;
+        using data_type = std::vector<
+            std::pair<Key, Value>,
+            Allocator>;
+
+        class uber_comparer_type : public Compare {
+        public:
+            uber_comparer_type() = default;
+            uber_comparer_type(const Compare& c) : Compare(c) {}
+
+            bool operator()(const Key& l, const Key& r) const {
+                return Compare::operator()(l, r);
+            }
+
+            bool operator()(const Key& l, typename data_type::const_reference r) const {
+                return Compare::operator()(l, r.first);
+            }
+
+            bool operator()(typename data_type::const_reference l, const Key& r) const {
+                return Compare::operator()(l.first, r);
+            }
+        };
     public:
         using key_type = Key;
         using mapped_type = Value;
@@ -40,5 +63,273 @@ namespace flat_hpp
         using const_iterator = typename data_type::const_iterator;
         using reverse_iterator = typename data_type::reverse_iterator;
         using const_reverse_iterator = typename data_type::const_reverse_iterator;
+
+        class value_compare final {
+        public:
+            bool operator()(const value_type& l, const value_type& r) const {
+                return compare_(l.first, r.first);
+            }
+        private:
+            friend class flat_map;
+            explicit value_compare(const key_compare& compare)
+            : compare_(compare) {}
+        private:
+            key_compare compare_;
+        };
+
+        static_assert(
+            std::is_same<typename allocator_type::value_type, value_type>::value,
+            "Allocator::value_type must be same type as value_type");
+    public:
+        explicit flat_map(
+            const Allocator& a)
+        : data_(a) {}
+
+        explicit flat_map(
+            const Compare& c = Compare(),
+            const Allocator& a = Allocator())
+        : data_(a)
+        , compare_(c) {}
+
+        template < typename InputIter >
+        flat_map(
+            InputIter first,
+            InputIter last,
+            const Allocator& a)
+        : data_(a) {
+            insert(first, last);
+        }
+
+        template < typename InputIter >
+        flat_map(
+            InputIter first,
+            InputIter last,
+            const Compare& c = Compare(),
+            const Allocator& a = Allocator())
+        : data_(a)
+        , compare_(c) {
+            insert(first, last);
+        }
+
+        flat_map(
+            std::initializer_list<value_type> ilist,
+            const Allocator& a)
+        : data_(a) {
+            insert(ilist);
+        }
+
+        flat_map(
+            std::initializer_list<value_type> ilist,
+            const Compare& c = Compare(),
+            const Allocator& a = Allocator())
+        : data_(a)
+        , compare_(c) {
+            insert(ilist);
+        }
+
+        iterator begin() noexcept { return data_.begin(); }
+        const_iterator begin() const noexcept { return data_.begin(); }
+        const_iterator cbegin() const noexcept { return data_.cbegin(); }
+
+        iterator end() noexcept { return data_.end(); }
+        const_iterator end() const noexcept { return data_.end(); }
+        const_iterator cend() const noexcept { return data_.cend(); }
+
+        reverse_iterator rbegin() noexcept { return data_.rbegin(); }
+        const_reverse_iterator rbegin() const noexcept { return data_.rbegin(); }
+        const_reverse_iterator crbegin() const noexcept { return data_.crbegin(); }
+
+        reverse_iterator rend() noexcept { return data_.rend(); }
+        const_reverse_iterator rend() const noexcept { return data_.rend(); }
+        const_reverse_iterator crend() const noexcept { return data_.crend(); }
+
+        bool empty() const noexcept {
+            return data_.empty();
+        }
+
+        size_type size() const noexcept {
+            return data_.size();
+        }
+
+        size_type max_size() const noexcept {
+            return data_.max_size();
+        }
+
+        mapped_type& operator[](key_type&& key) {
+            return insert(value_type(std::move(key), mapped_type())).first->second;
+        }
+
+        mapped_type& operator[](const key_type& key) {
+            return insert(value_type(key, mapped_type())).first->second;
+        }
+
+        mapped_type& at(const key_type& key) {
+            const auto iter = find(key);
+            if ( iter != end() ) {
+                return iter->second;
+            }
+            throw std::out_of_range("flat_map::at: key not found");
+        }
+
+        const mapped_type& at(const key_type& key) const {
+            const auto iter = find(key);
+            if ( iter != end() ) {
+                return iter->second;
+            }
+            throw std::out_of_range("flat_map::at: key not found");
+        }
+
+        std::pair<iterator, bool> insert(const value_type& value) {
+            const iterator iter = lower_bound(value.first);
+            return iter == end() || compare_(value.first, iter->first)
+                ? std::make_pair(data_.insert(iter, value), true)
+                : std::make_pair(iter, false);
+        }
+
+        iterator insert(const_iterator hint, const value_type& value) {
+            return (hint == begin() || compare_((hint - 1)->first, value.first))
+                && (hint == end() || compare_(value.first, hint->first))
+                ? data_.insert(hint, std::move(value))
+                : insert(std::move(value)).first;
+        }
+
+        template < typename InputIter >
+        void insert(InputIter first, InputIter last) {
+            while ( first != last ) {
+                insert(*first++);
+            }
+        }
+
+        void insert(std::initializer_list<value_type> ilist) {
+            insert(ilist.begin(), ilist.end());
+        }
+
+        template < typename... Args >
+        std::pair<iterator, bool> emplace(Args&&... args) {
+            return insert(value_type(std::forward<Args>(args)...));
+        }
+
+        template < typename... Args >
+        iterator emplace_hint(const_iterator hint, Args&&... args) {
+            return insert(hint, value_type(std::forward<Args>(args)...));
+        }
+
+        void clear() noexcept {
+            data_.clear();
+        }
+
+        iterator erase(const_iterator iter) {
+            return data_.erase(iter);
+        }
+
+        iterator erase(const_iterator first, const_iterator last) {
+            return data_.erase(first, last);
+        }
+
+        size_type erase(const key_type& key) {
+            const iterator iter = find(key);
+            return iter != end()
+                ? (erase(iter), 1)
+                : 0;
+        }
+
+        void swap(flat_map& other) {
+            using std::swap;
+            swap(data_, other.data_);
+            swap(compare_, other.compare_);
+        }
+
+        size_type count(const key_type& key) const {
+            const auto iter = find(key);
+            return iter != end() ? 1 : 0;
+        }
+
+        iterator find(const key_type& key) {
+            const iterator iter = lower_bound(key);
+            return iter != end() && !compare_(key, iter->first)
+                ? iter
+                : end();
+        }
+
+        const_iterator find(const key_type& key) const {
+            const const_iterator iter = lower_bound(key);
+            return iter != end() && !compare_(key, iter->first)
+                ? iter
+                : end();
+        }
+
+        std::pair<iterator, iterator> equal_range(const key_type& key) {
+            return std::equal_range(begin(), end(), key, compare_);
+        }
+
+        std::pair<const_iterator, const_iterator> equal_range(const key_type& key) const {
+            return std::equal_range(begin(), end(), key, compare_);
+        }
+
+        iterator lower_bound(const key_type& key) {
+            return std::lower_bound(begin(), end(), key, compare_);
+        }
+
+        const_iterator lower_bound(const key_type& key) const {
+            return std::lower_bound(begin(), end(), key, compare_);
+        }
+
+        iterator upper_bound(const key_type& key) {
+            return std::upper_bound(begin(), end(), key, compare_);
+        }
+
+        const_iterator upper_bound(const key_type& key) const {
+            return std::upper_bound(begin(), end(), key, compare_);
+        }
+
+        key_compare key_comp() const {
+            return compare_;
+        }
+
+        value_compare value_comp() const {
+            return value_compare(compare_);
+        }
+    private:
+        data_type data_;
+        uber_comparer_type compare_;
     };
 }
+
+namespace flat_hpp
+{
+    template < typename K, typename V, typename C, typename A >
+    void swap(flat_map<K, V, C, A>& l, flat_map<K, V, C, A>& r) {
+        l.swap(r);
+    }
+
+    template < typename K, typename V, typename C, typename A >
+    bool operator==(const flat_map<K, V, C, A>& l, const flat_map<K, V, C, A>& r) {
+        return l.size() == r.size()
+            && std::equal(l.begin(), l.end(), r.begin(), r.end());
+    }
+
+    template < typename K, typename V, typename C, typename A >
+    bool operator!=(const flat_map<K, V, C, A>& l, const flat_map<K, V, C, A>& r) {
+        return !(l == r);
+    }
+
+    template < typename K, typename V, typename C, typename A >
+    bool operator<(const flat_map<K, V, C, A>& l, const flat_map<K, V, C, A>& r) {
+        return std::lexicographical_compare(l.begin(), l.end(), r.begin(), r.end());
+    }
+
+    template < typename K, typename V, typename C, typename A >
+    bool operator>(const flat_map<K, V, C, A>& l, const flat_map<K, V, C, A>& r) {
+        return r < l;
+    }
+
+    template < typename K, typename V, typename C, typename A >
+    bool operator<=(const flat_map<K, V, C, A>& l, const flat_map<K, V, C, A>& r) {
+        return !(r < l);
+    }
+
+    template < typename K, typename V, typename C, typename A >
+    bool operator>=(const flat_map<K, V, C, A>& l, const flat_map<K, V, C, A>& r) {
+        return !(l < r);
+    }
+}
diff --git a/flat_map_tests.cpp b/flat_map_tests.cpp
index 2a51191..1957624 100644
--- a/flat_map_tests.cpp
+++ b/flat_map_tests.cpp
@@ -8,15 +8,50 @@
 #include "catch.hpp"
 
 #include "flat_map.hpp"
-namespace flat = flat_hpp;
+using namespace flat_hpp;
 
 namespace
 {
+    template < typename T >
+    class dummy_allocator {
+    public:
+        using value_type = T;
+
+        dummy_allocator() = default;
+
+        template < typename U >
+        dummy_allocator(const dummy_allocator<U>&) noexcept {
+        }
+
+        T* allocate(std::size_t n) noexcept {
+            return static_cast<T*>(std::malloc(sizeof(T) * n));
+        }
+
+        void deallocate(T* p, std::size_t n) noexcept {
+            (void)n;
+            std::free(p);
+        }
+    };
+
+    template < typename T, typename U >
+    bool operator==(const dummy_allocator<T>&, const dummy_allocator<U>&) noexcept {
+        return true;
+    }
+
+    template < typename T, typename U >
+    bool operator!=(const dummy_allocator<T>& l, const dummy_allocator<U>& r) noexcept {
+        return !(l == r);
+    }
+
+    template < typename T >
+    constexpr std::add_const_t<T>& my_as_const(T& t) noexcept {
+        return t;
+    }
 }
 
 TEST_CASE("flat_map") {
-    {
-        using map_t = flat::flat_map<int, unsigned>;
+    SECTION("types") {
+        using map_t = flat_map<int, unsigned>;
 
         static_assert(
             std::is_same<map_t::key_type, int>::value,
@@ -25,7 +60,7 @@ TEST_CASE("flat_map") {
             std::is_same<map_t::mapped_type, unsigned>::value,
             "unit test static error");
         static_assert(
-            std::is_same<map_t::value_type, std::pair<const int, unsigned>>::value,
+            std::is_same<map_t::value_type, std::pair<int, unsigned>>::value,
             "unit test static error");
 
         static_assert(
@@ -36,17 +71,263 @@ TEST_CASE("flat_map") {
             "unit test static error");
 
         static_assert(
-            std::is_same<map_t::reference, std::pair<const int, unsigned>&>::value,
+            std::is_same<map_t::reference, std::pair<int, unsigned>&>::value,
             "unit test static error");
         static_assert(
-            std::is_same<map_t::const_reference, const std::pair<const int, unsigned>&>::value,
+            std::is_same<map_t::const_reference, const std::pair<int, unsigned>&>::value,
             "unit test static error");
 
         static_assert(
-            std::is_same<map_t::pointer, std::pair<const int, unsigned>*>::value,
+            std::is_same<map_t::pointer, std::pair<int, unsigned>*>::value,
             "unit test static error");
         static_assert(
-            std::is_same<map_t::const_pointer, const std::pair<const int, unsigned>*>::value,
+            std::is_same<map_t::const_pointer, const std::pair<int, unsigned>*>::value,
             "unit test static error");
     }
+    SECTION("ctors") {
+        using alloc_t = dummy_allocator<
+            std::pair<int,unsigned>>;
+
+        using map_t = flat_map<
+            int,
+            unsigned,
+            std::less<int>,
+            alloc_t>;
+
+        using map2_t = flat_map<
+            int,
+            unsigned,
+            std::greater<int>,
+            alloc_t>;
+
+        {
+            auto s0 = map_t();
+            auto s1 = map2_t(alloc_t());
+            auto s2 = map_t(std::less<int>());
+            auto s3 = map2_t(std::greater<int>(), alloc_t());
+        }
+
+        {
+            using vec_t = std::vector<std::pair<int,unsigned>>;
+
+            vec_t v{{1,30},{2,20},{3,10}};
+            auto s0 = map_t(v.cbegin(), v.cend());
+            auto s1 = map2_t(v.cbegin(), v.cend(), alloc_t());
+            auto s2 = map_t(v.cbegin(), v.cend(), std::less<int>());
+            auto s3 = map2_t(v.cbegin(), v.cend(), std::greater<int>(), alloc_t());
+
+            REQUIRE(vec_t(s0.begin(), s0.end()) == vec_t({{1,30},{2,20},{3,10}}));
+            REQUIRE(vec_t(s1.begin(), s1.end()) == vec_t({{3,10},{2,20},{1,30}}));
+            REQUIRE(vec_t(s2.begin(), s2.end()) == vec_t({{1,30},{2,20},{3,10}}));
+            REQUIRE(vec_t(s3.begin(), s3.end()) == vec_t({{3,10},{2,20},{1,30}}));
+        }
+
+        {
+            auto s0 = map_t({{0,1}, {1,2}});
+            auto s1 = map_t({{0,1}, {1,2}}, alloc_t());
+            auto s2 = map_t({{0,1}, {1,2}}, std::less<int>());
+            auto s3 = map_t({{0,1}, {1,2}}, std::less<int>(), alloc_t());
+        }
+    }
+    SECTION("capacity") {
+        using map_t = flat_map<int, unsigned>;
+        map_t s0;
+
+        REQUIRE(s0.empty());
+        REQUIRE_FALSE(s0.size());
+        REQUIRE(s0.max_size() == std::allocator<std::pair<int,unsigned>>().max_size());
+
+        s0.insert({2,42});
+
+        REQUIRE_FALSE(s0.empty());
+        REQUIRE(s0.size() == 1u);
+        REQUIRE(s0.max_size() == std::allocator<std::pair<int,unsigned>>().max_size());
+
+        s0.insert({2,84});
+        REQUIRE(s0.size() == 1u);
+
+        s0.insert({3,84});
+        REQUIRE(s0.size() == 2u);
+
+        s0.clear();
+
+        REQUIRE(s0.empty());
+        REQUIRE_FALSE(s0.size());
+        REQUIRE(s0.max_size() == std::allocator<std::pair<int,unsigned>>().max_size());
+    }
+    SECTION("access") {
+        using map_t = flat_map<int, unsigned>;
+        map_t s0;
+        s0[1] = 42;
+        REQUIRE(s0 == map_t{{1,42}});
+        s0[1] = 84;
+        REQUIRE(s0 == map_t{{1,84}});
+
+        REQUIRE(s0.at(1) == 84);
+        REQUIRE(my_as_const(s0).at(1) == 84);
+        REQUIRE_THROWS_AS(s0.at(0), std::out_of_range);
+        REQUIRE_THROWS_AS(my_as_const(s0).at(0), std::out_of_range);
+    }
+    SECTION("inserts") {
+        struct obj_t {
+            obj_t(int i) : i(i) {}
+            int i;
+
+            bool operator<(const obj_t& o) const {
+                return i < o.i;
+            }
+
+            bool operator==(const obj_t& o) const {
+                return i == o.i;
+            }
+        };
+
+        using map_t = flat_map<int, obj_t>;
+
+        {
+            map_t s0;
+
+            auto i0 = s0.insert(std::make_pair(1, 42));
+            REQUIRE(s0 == map_t{{1,42}});
+            REQUIRE(i0 == std::make_pair(s0.begin(), true));
+
+            auto i1 = s0.insert(std::make_pair(1, obj_t(42)));
+            REQUIRE(s0 == map_t{{1,42}});
+            REQUIRE(i1 == std::make_pair(s0.begin(), false));
+
+            auto i2 = s0.insert(std::make_pair(2, obj_t(42)));
+            REQUIRE(s0 == map_t{{1,42},{2,42}});
+            REQUIRE(i2 == std::make_pair(s0.begin() + 1, true));
+
+            auto i3 = s0.insert(s0.cend(), std::make_pair(3, 84));
+            REQUIRE(i3 == s0.begin() + 2);
+
+            s0.insert(s0.cend(), std::make_pair(4, obj_t(84)));
+            auto i4 = s0.insert(s0.cend(), std::make_pair(0, obj_t(21)));
+            REQUIRE(i4 == s0.begin());
+
+            auto i5 = s0.emplace(5, 100500);
+            REQUIRE(i5 == std::make_pair(s0.end() - 1, true));
+            REQUIRE(s0 == map_t{{0,21},{1,42},{2,42},{3,84},{4,84},{5,100500}});
+
+            auto i6 = s0.emplace_hint(s0.cend(), 6, 100500);
+            REQUIRE(i6 == s0.end() - 1);
+            REQUIRE(s0 == map_t{{0,21},{1,42},{2,42},{3,84},{4,84},{5,100500},{6,100500}});
+        }
+    }
+    SECTION("erasers") {
+        using map_t = flat_map<int, unsigned>;
+        {
+            map_t s0{{1,2},{2,3},{3,4}};
+            s0.clear();
+            REQUIRE(s0.empty());
+        }
+        {
+            map_t s0{{1,2},{2,3},{3,4}};
+            auto i = s0.erase(s0.find(2));
+            REQUIRE(i == s0.begin() + 1);
+            REQUIRE(s0 == map_t{{1,2},{3,4}});
+        }
+        {
+            map_t s0{{1,2},{2,3},{3,4}};
+            auto i = s0.erase(s0.begin() + 1, s0.end());
+            REQUIRE(i == s0.end());
+            REQUIRE(s0 == map_t{{1,2}});
+        }
+        {
+            map_t s0{{1,2},{2,3},{3,4}};
+            REQUIRE(s0.erase(1) == 1);
+            REQUIRE(s0.erase(6) == 0);
+            REQUIRE(s0 == map_t{{2,3},{3,4}});
+        }
+        {
+            map_t s0{{1,2},{2,3},{3,4}};
+            map_t s1{{2,3},{3,4},{5,6}};
+            s0.swap(s1);
+            REQUIRE(s0 == map_t{{2,3},{3,4},{5,6}});
+            REQUIRE(s1 == map_t{{1,2},{2,3},{3,4}});
+            swap(s1, s0);
+            REQUIRE(s0 == map_t{{1,2},{2,3},{3,4}});
+            REQUIRE(s1 == map_t{{2,3},{3,4},{5,6}});
+        }
+    }
+    SECTION("lookup") {
+        using map_t = flat_map<int, unsigned>;
+        {
+            map_t s0{{1,2},{2,3},{3,4},{4,5},{5,6}};
+            REQUIRE(s0.count(3));
+            REQUIRE_FALSE(s0.count(6));
+            REQUIRE(my_as_const(s0).count(5));
+            REQUIRE_FALSE(my_as_const(s0).count(0));
+        }
+        {
+            map_t s0{{1,2},{2,3},{3,4},{4,5},{5,6}};
+            REQUIRE(s0.find(2) == s0.begin() + 1);
+            REQUIRE(my_as_const(s0).find(3) == s0.cbegin() + 2);
+            REQUIRE(s0.find(6) == s0.end());
+            REQUIRE(my_as_const(s0).find(0) == s0.cend());
+        }
+        {
+            map_t s0{{1,2},{2,3},{3,4},{4,5},{5,6}};
+            REQUIRE(s0.equal_range(3) == std::make_pair(s0.begin() + 2, s0.begin() + 3));
+            REQUIRE(s0.equal_range(6) == std::make_pair(s0.end(), s0.end()));
+            REQUIRE(my_as_const(s0).equal_range(3) == std::make_pair(s0.cbegin() + 2, s0.cbegin() + 3));
+            REQUIRE(my_as_const(s0).equal_range(0) == std::make_pair(s0.cbegin(), s0.cbegin()));
+        }
+        {
+            map_t s0{{0,1},{3,2},{6,3}};
+            REQUIRE(s0.lower_bound(0) == s0.begin());
+            REQUIRE(s0.lower_bound(1) == s0.begin() + 1);
+            REQUIRE(s0.lower_bound(10) == s0.end());
+            REQUIRE(my_as_const(s0).lower_bound(-1) == s0.cbegin());
+            REQUIRE(my_as_const(s0).lower_bound(7) == s0.cbegin() + 3);
+        }
+    }
+    SECTION("observers") {
+        struct my_less {
+            int i;
+            my_less(int i) : i(i) {}
+            bool operator()(int l, int r) const {
+                return l < r;
+            }
+        };
+        using map_t = flat_map<int, unsigned, my_less>;
+        map_t s0(my_less(42));
+        REQUIRE(my_as_const(s0).key_comp().i == 42);
+        REQUIRE(my_as_const(s0).value_comp()({2,50},{4,20}));
+    }
+    SECTION("operators") {
+        using map_t = flat_map<int, unsigned>;
+
+        REQUIRE(map_t{{1,2},{3,4}} == map_t{{3,4},{1,2}});
+        REQUIRE_FALSE(map_t{{1,2},{3,4}} == map_t{{2,4},{1,2}});
+        REQUIRE_FALSE(map_t{{1,2},{3,4}} == map_t{{1,3},{1,2}});
+        REQUIRE_FALSE(map_t{{1,2},{3,4}} == map_t{{3,4},{1,2},{0,0}});
+
+        REQUIRE_FALSE(map_t{{1,2},{3,4}} != map_t{{3,4},{1,2}});
+        REQUIRE(map_t{{1,2},{3,4}} != map_t{{2,4},{1,2}});
+        REQUIRE(map_t{{1,2},{3,4}} != map_t{{1,3},{1,2}});
+        REQUIRE(map_t{{1,2},{3,4}} != map_t{{3,4},{1,2},{0,0}});
+
+        REQUIRE(map_t{{0,2},{3,4}} < map_t{{1,2},{3,4}});
+        REQUIRE(map_t{{1,1},{3,4}} < map_t{{1,2},{3,4}});
+        REQUIRE(map_t{{1,2},{3,4}} < map_t{{1,2},{3,4},{5,6}});
+
+        REQUIRE(map_t{{0,2},{3,4}} <= map_t{{1,2},{3,4}});
+        REQUIRE(map_t{{1,1},{3,4}} <= map_t{{1,2},{3,4}});
+        REQUIRE(map_t{{1,2},{3,4}} <= map_t{{1,2},{3,4},{5,6}});
+
+        REQUIRE(map_t{{1,2},{3,4}} > map_t{{0,2},{3,4}});
+        REQUIRE(map_t{{1,2},{3,4}} > map_t{{1,1},{3,4}});
+        REQUIRE(map_t{{1,2},{3,4},{5,6}} > map_t{{1,2},{3,4}});
+
+        REQUIRE(map_t{{1,2},{3,4}} >= map_t{{0,2},{3,4}});
+        REQUIRE(map_t{{1,2},{3,4}} >= map_t{{1,1},{3,4}});
+        REQUIRE(map_t{{1,2},{3,4},{5,6}} >= map_t{{1,2},{3,4}});
+
+        REQUIRE_FALSE(map_t{{1,2},{3,4}} < map_t{{1,2},{3,4}});
+        REQUIRE(map_t{{1,2},{3,4}} <= map_t{{1,2},{3,4}});
+        REQUIRE_FALSE(map_t{{1,2},{3,4}} > map_t{{1,2},{3,4}});
+        REQUIRE(map_t{{1,2},{3,4}} >= map_t{{1,2},{3,4}});
+    }
 }
diff --git a/flat_set.hpp b/flat_set.hpp
index f132a1a..f5652f0 100644
--- a/flat_set.hpp
+++ b/flat_set.hpp
@@ -9,8 +9,11 @@
 #include <vector>
 #include <memory>
 #include <utility>
+#include <iterator>
+#include <algorithm>
 #include <functional>
 #include <type_traits>
+#include <initializer_list>
 
 namespace flat_hpp
 {
@@ -39,5 +42,250 @@ namespace flat_hpp
         using const_iterator = typename data_type::const_iterator;
         using reverse_iterator = typename data_type::reverse_iterator;
         using const_reverse_iterator = typename data_type::const_reverse_iterator;
+
+        static_assert(
+            std::is_same<typename allocator_type::value_type, value_type>::value,
+            "Allocator::value_type must be same type as value_type");
+    public:
+        explicit flat_set(
+            const Allocator& a)
+        : data_(a) {}
+
+        explicit flat_set(
+            const Compare& c = Compare(),
+            const Allocator& a = Allocator())
+        : data_(a)
+        , compare_(c) {}
+
+        template < typename InputIter >
+        flat_set(
+            InputIter first,
+            InputIter last,
+            const Allocator& a)
+        : data_(a) {
+            insert(first, last);
+        }
+
+        template < typename InputIter >
+        flat_set(
+            InputIter first,
+            InputIter last,
+            const Compare& c = Compare(),
+            const Allocator& a = Allocator())
+        : data_(a)
+        , compare_(c) {
+            insert(first, last);
+        }
+
+        flat_set(
+            std::initializer_list<value_type> ilist,
+            const Allocator& a)
+        : data_(a) {
+            insert(ilist);
+        }
+
+        flat_set(
+            std::initializer_list<value_type> ilist,
+            const Compare& c = Compare(),
+            const Allocator& a = Allocator())
+        : data_(a)
+        , compare_(c) {
+            insert(ilist);
+        }
+
+        iterator begin() noexcept { return data_.begin(); }
+        const_iterator begin() const noexcept { return data_.begin(); }
+        const_iterator cbegin() const noexcept { return data_.cbegin(); }
+
+        iterator end() noexcept { return data_.end(); }
+        const_iterator end() const noexcept { return data_.end(); }
+        const_iterator cend() const noexcept { return data_.cend(); }
+
+        reverse_iterator rbegin() noexcept { return data_.rbegin(); }
+        const_reverse_iterator rbegin() const noexcept { return data_.rbegin(); }
+        const_reverse_iterator crbegin() const noexcept { return data_.crbegin(); }
+
+        reverse_iterator rend() noexcept { return data_.rend(); }
+        const_reverse_iterator rend() const noexcept { return data_.rend(); }
+        const_reverse_iterator crend() const noexcept { return data_.crend(); }
+
+        bool empty() const noexcept {
+            return data_.empty();
+        }
+
+        size_type size() const noexcept {
+            return data_.size();
+        }
+
+        size_type max_size() const noexcept {
+            return data_.max_size();
+        }
+
+        std::pair<iterator, bool> insert(value_type&& value) {
+            const iterator iter = lower_bound(value);
+            return iter == end() || compare_(value, *iter)
+                ? std::make_pair(data_.insert(iter, std::move(value)), true)
+                : std::make_pair(iter, false);
+        }
+
+        std::pair<iterator, bool> insert(const value_type& value) {
+            const iterator iter = lower_bound(value);
+            return iter == end() || compare_(value, *iter)
+                ? std::make_pair(data_.insert(iter, value), true)
+                : std::make_pair(iter, false);
+        }
+
+        iterator insert(const_iterator hint, value_type&& value) {
+            return (hint == begin() || compare_(*(hint - 1), value))
+                && (hint == end() || compare_(value, *hint))
+                ? data_.insert(hint, std::move(value))
+                : insert(std::move(value)).first;
+        }
+
+        iterator insert(const_iterator hint, const value_type& value) {
+            return (hint == begin() || compare_(*(hint - 1), value))
+                && (hint == end() || compare_(value, *hint))
+                ? data_.insert(hint, value)
+                : insert(value).first;
+        }
+
+        template < typename InputIter >
+        void insert(InputIter first, InputIter last) {
+            while ( first != last ) {
+                insert(*first++);
+            }
+        }
+
+        void insert(std::initializer_list<value_type> ilist) {
+            insert(ilist.begin(), ilist.end());
+        }
+
+        template < typename... Args >
+        std::pair<iterator, bool> emplace(Args&&... args) {
+            return insert(value_type(std::forward<Args>(args)...));
+        }
+
+        template < typename... Args >
+        iterator emplace_hint(const_iterator hint, Args&&... args) {
+            return insert(hint, value_type(std::forward<Args>(args)...));
+        }
+
+        void clear() noexcept {
+            data_.clear();
+        }
+
+        iterator erase(const_iterator iter) {
+            return data_.erase(iter);
+        }
+
+        iterator erase(const_iterator first, const_iterator last) {
+            return data_.erase(first, last);
+        }
+
+        size_type erase(const key_type& key) {
+            const iterator iter = find(key);
+            return iter != end()
+                ? (erase(iter), 1)
+                : 0;
+        }
+
+        void swap(flat_set& other) {
+            using std::swap;
+            swap(data_, other.data_);
+            swap(compare_, other.compare_);
+        }
+
+        size_type count(const key_type& key) const {
+            const const_iterator iter = find(key);
+            return iter != end() ? 1 : 0;
+        }
+
+        iterator find(const key_type& key) {
+            const iterator iter = lower_bound(key);
+            return iter != end() && !compare_(key, *iter)
+                ? iter
+                : end();
+        }
+
+        const_iterator find(const key_type& key) const {
+            const const_iterator iter = lower_bound(key);
+            return iter != end() && !compare_(key, *iter)
+                ? iter
+                : end();
+        }
+
+        std::pair<iterator, iterator> equal_range(const key_type& key) {
+            return std::equal_range(begin(), end(), key, compare_);
+        }
+
+        std::pair<const_iterator, const_iterator> equal_range(const key_type& key) const {
+            return std::equal_range(begin(), end(), key, compare_);
+        }
+
+        iterator lower_bound(const key_type& key) {
+            return std::lower_bound(begin(), end(), key, compare_);
+        }
+
+        const_iterator lower_bound(const key_type& key) const {
+            return std::lower_bound(begin(), end(), key, compare_);
+        }
+
+        iterator upper_bound(const key_type& key) {
+            return std::upper_bound(begin(), end(), key, compare_);
+        }
+
+        const_iterator upper_bound(const key_type& key) const {
+            return std::upper_bound(begin(), end(), key, compare_);
+        }
+
+        key_compare key_comp() const {
+            return compare_;
+        }
+
+        value_compare value_comp() const {
+            return value_compare(compare_);
+        }
+    private:
+        data_type data_;
+        key_compare compare_;
     };
 }
+
+namespace flat_hpp
+{
+    template < typename K, typename C, typename A >
+    void swap(flat_set<K, C, A>& l, flat_set<K, C, A>& r) {
+        l.swap(r);
+    }
+
+    template < typename K, typename C, typename A >
+    bool operator==(const flat_set<K, C, A>& l, const flat_set<K, C, A>& r) {
+        return l.size() == r.size()
+            && std::equal(l.begin(), l.end(), r.begin(), r.end());
+    }
+
+    template < typename K, typename C, typename A >
+    bool operator!=(const flat_set<K, C, A>& l, const flat_set<K, C, A>& r) {
+        return !(l == r);
+    }
+
+    template < typename K, typename C, typename A >
+    bool operator<(const flat_set<K, C, A>& l, const flat_set<K, C, A>& r) {
+        return std::lexicographical_compare(l.begin(), l.end(), r.begin(), r.end());
+    }
+
+    template < typename K, typename C, typename A >
+    bool operator>(const flat_set<K, C, A>& l, const flat_set<K, C, A>& r) {
+        return r < l;
+    }
+
+    template < typename K, typename C, typename A >
+    bool operator<=(const flat_set<K, C, A>& l, const flat_set<K, C, A>& r) {
+        return !(r < l);
+    }
+
+    template < typename K, typename C, typename A >
+    bool operator>=(const flat_set<K, C, A>& l, const flat_set<K, C, A>& r) {
+        return !(l < r);
+    }
+}
diff --git a/flat_set_tests.cpp b/flat_set_tests.cpp
index 284ee7a..d103f55 100644
--- a/flat_set_tests.cpp
+++ b/flat_set_tests.cpp
@@ -8,15 +8,50 @@
 #include "catch.hpp"
 
 #include "flat_set.hpp"
-namespace flat = flat_hpp;
+using namespace flat_hpp;
 
 namespace
 {
+    template < typename T >
+    class dummy_allocator {
+    public:
+        using value_type = T;
+
+        dummy_allocator() = default;
+
+        template < typename U >
+        dummy_allocator(const dummy_allocator<U>&) noexcept {
+        }
+
+        T* allocate(std::size_t n) noexcept {
+            return static_cast<T*>(std::malloc(sizeof(T) * n));
+        }
+
+        void deallocate(T* p, std::size_t n) noexcept {
+            (void)n;
+            std::free(p);
+        }
+    };
+
+    template < typename T, typename U >
+    bool operator==(const dummy_allocator<T>&, const dummy_allocator<U>&) noexcept {
+        return true;
+    }
+
+    template < typename T, typename U >
+    bool operator!=(const dummy_allocator<T>& l, const dummy_allocator<U>& r) noexcept {
+        return !(l == r);
+    }
+
+    template < typename T >
+    constexpr std::add_const_t<T>& my_as_const(T& t) noexcept {
+        return t;
+    }
 }
 
 TEST_CASE("flat_set") {
-    {
-        using set_t = flat::flat_set<int>;
+    SECTION("types") {
+        using set_t = flat_set<int>;
 
         static_assert(
             std::is_same<set_t::key_type, int>::value,
@@ -46,4 +81,251 @@ TEST_CASE("flat_set") {
             std::is_same<set_t::const_pointer, const int*>::value,
             "unit test static error");
     }
+    SECTION("ctors") {
+        using alloc_t = dummy_allocator<int>;
+        using set_t = flat_set<int, std::less<int>, alloc_t>;
+        using set2_t = flat_set<int, std::greater<int>, alloc_t>;
+
+        {
+            auto s0 = set_t();
+            auto s1 = set2_t(alloc_t());
+            auto s2 = set_t(std::less<int>());
+            auto s3 = set2_t(std::greater<int>(), alloc_t());
+        }
+
+        {
+            std::vector<int> v{1,2,3};
+            auto s0 = set_t(v.cbegin(), v.cend());
+            auto s1 = set2_t(v.cbegin(), v.cend(), alloc_t());
+            auto s2 = set_t(v.cbegin(), v.cend(), std::less<int>());
+            auto s3 = set2_t(v.cbegin(), v.cend(), std::greater<int>(), alloc_t());
+
+            REQUIRE(std::vector<int>(s0.begin(), s0.end()) == std::vector<int>({1,2,3}));
+            REQUIRE(std::vector<int>(s1.begin(), s1.end()) == std::vector<int>({3,2,1}));
+            REQUIRE(std::vector<int>(s2.begin(), s2.end()) == std::vector<int>({1,2,3}));
+            REQUIRE(std::vector<int>(s3.begin(), s3.end()) == std::vector<int>({3,2,1}));
+        }
+
+        {
+            auto s0 = set_t({0,1,2});
+            auto s1 = set2_t({0,1,2}, alloc_t());
+            auto s2 = set_t({0,1,2}, std::less<int>());
+            auto s3 = set2_t({0,1,2}, std::greater<int>(), alloc_t());
+
+            REQUIRE(std::vector<int>(s0.begin(), s0.end()) == std::vector<int>({0,1,2}));
+            REQUIRE(std::vector<int>(s1.begin(), s1.end()) == std::vector<int>({2,1,0}));
+            REQUIRE(std::vector<int>(s2.begin(), s2.end()) == std::vector<int>({0,1,2}));
+            REQUIRE(std::vector<int>(s3.begin(), s3.end()) == std::vector<int>({2,1,0}));
+        }
+    }
+    SECTION("capacity") {
+        using set_t = flat_set<int>;
+        set_t s0;
+
+        REQUIRE(s0.empty());
+        REQUIRE_FALSE(s0.size());
+        REQUIRE(s0.max_size() == std::allocator<int>().max_size());
+
+        s0.insert(42);
+
+        REQUIRE_FALSE(s0.empty());
+        REQUIRE(s0.size() == 1u);
+        REQUIRE(s0.max_size() == std::allocator<int>().max_size());
+
+        s0.insert(42);
+        REQUIRE(s0.size() == 1u);
+
+        s0.insert(84);
+        REQUIRE(s0.size() == 2u);
+
+        s0.clear();
+
+        REQUIRE(s0.empty());
+        REQUIRE_FALSE(s0.size());
+        REQUIRE(s0.max_size() == std::allocator<int>().max_size());
+    }
+    SECTION("inserts") {
+        struct obj_t {
+            obj_t(int i) : i(i) {}
+            int i;
+
+            bool operator<(const obj_t& o) const {
+                return i < o.i;
+            }
+
+            bool operator==(const obj_t& o) const {
+                return i == o.i;
+            }
+        };
+
+        using set_t = flat_set<obj_t>;
+
+        {
+            set_t s0;
+
+            auto i0 = s0.insert(1);
+            REQUIRE(s0 == set_t{1});
+            REQUIRE(i0 == std::make_pair(s0.begin(), true));
+
+            auto i1 = s0.insert(obj_t(1));
+            REQUIRE(s0 == set_t{1});
+            REQUIRE(i1 == std::make_pair(s0.begin(), false));
+
+            auto i2 = s0.insert(obj_t(2));
+            REQUIRE(s0 == set_t{1,2});
+            REQUIRE(i2 == std::make_pair(s0.begin() + 1, true));
+
+            auto o2 = obj_t(2);
+            auto i3 = s0.insert(o2);
+            REQUIRE(i3 == std::make_pair(s0.begin() + 1, false));
+
+            s0.insert(s0.cbegin(), 1);
+            s0.insert(s0.cbegin(), 2);
+            s0.insert(s0.cend(), 1);
+            s0.insert(s0.cend(), 2);
+            REQUIRE(s0 == set_t{1,2});
+
+            s0.insert(s0.cbegin(), 0);
+            REQUIRE(s0 == set_t{0,1,2});
+            s0.insert(s0.cend(), 3);
+            REQUIRE(s0 == set_t{0,1,2,3});
+            s0.insert(s0.cbegin(), 4);
+            s0.insert(s0.cend(), -1);
+            REQUIRE(s0 == set_t{-1,0,1,2,3,4});
+
+            s0.insert(s0.cbegin() + 2, obj_t(5));
+            REQUIRE(s0 == set_t{-1,0,1,2,3,4,5});
+            s0.insert(s0.cbegin(), obj_t(-2));
+            REQUIRE(s0 == set_t{-2,-1,0,1,2,3,4,5});
+        }
+
+        {
+            set_t s0;
+
+            auto e0 = s0.emplace(3);
+            REQUIRE(s0 == set_t{3});
+            REQUIRE(e0 == std::make_pair(s0.begin(), true));
+
+            auto e1 = s0.emplace(obj_t(3));
+            REQUIRE(e1 == std::make_pair(s0.begin(), false));
+
+            auto e2 = s0.emplace(4);
+            REQUIRE(s0 == set_t{3,4});
+            REQUIRE(e2 == std::make_pair(s0.begin() + 1, true));
+
+            auto e3 = s0.emplace_hint(s0.cbegin(), 1);
+            REQUIRE(e3 == s0.begin());
+            auto e4 = s0.emplace_hint(s0.cend(), 2);
+            REQUIRE(e4 == s0.begin() + 1);
+            s0.emplace_hint(s0.cbegin(), 5);
+            s0.emplace_hint(s0.cend(), 6);
+            REQUIRE(s0 == set_t{1,2,3,4,5,6});
+        }
+    }
+    SECTION("erasers") {
+        using set_t = flat_set<int>;
+        {
+            set_t s0{1,2,3,4,5};
+            s0.clear();
+            REQUIRE(s0.empty());
+        }
+        {
+            set_t s0{1,2,3,4,5};
+            auto i = s0.erase(s0.find(3));
+            REQUIRE(i == s0.begin() + 2);
+            REQUIRE(s0 == set_t{1,2,4,5});
+        }
+        {
+            set_t s0{1,2,3,4,5};
+            auto i = s0.erase(s0.begin() + 2, s0.end());
+            REQUIRE(i == s0.end());
+            REQUIRE(s0 == set_t{1,2});
+        }
+        {
+            set_t s0{1,2,3,4,5};
+            REQUIRE(s0.erase(2) == 1);
+            REQUIRE(s0.erase(6) == 0);
+            REQUIRE(s0 == set_t{1,3,4,5});
+        }
+        {
+            set_t s0{1,2,3};
+            set_t s1{3,4,5};
+            s0.swap(s1);
+            REQUIRE(s0 == set_t{3,4,5});
+            REQUIRE(s1 == set_t{1,2,3});
+            swap(s1, s0);
+            REQUIRE(s0 == set_t{1,2,3});
+            REQUIRE(s1 == set_t{3,4,5});
+        }
+    }
+    SECTION("lookup") {
+        using set_t = flat_set<int>;
+        {
+            set_t s0{1,2,3,4,5};
+            REQUIRE(s0.count(3));
+            REQUIRE_FALSE(s0.count(6));
+            REQUIRE(my_as_const(s0).count(5));
+            REQUIRE_FALSE(my_as_const(s0).count(0));
+        }
+        {
+            set_t s0{1,2,3,4,5};
+            REQUIRE(s0.find(2) == s0.begin() + 1);
+            REQUIRE(my_as_const(s0).find(3) == s0.cbegin() + 2);
+            REQUIRE(s0.find(6) == s0.end());
+            REQUIRE(my_as_const(s0).find(0) == s0.cend());
+        }
+        {
+            set_t s0{1,2,3,4,5};
+            REQUIRE(s0.equal_range(3) == std::make_pair(s0.begin() + 2, s0.begin() + 3));
+            REQUIRE(s0.equal_range(6) == std::make_pair(s0.end(), s0.end()));
+            REQUIRE(my_as_const(s0).equal_range(3) == std::make_pair(s0.cbegin() + 2, s0.cbegin() + 3));
+            REQUIRE(my_as_const(s0).equal_range(0) == std::make_pair(s0.cbegin(), s0.cbegin()));
+        }
+        {
+            set_t s0{0,3,6,9};
+            REQUIRE(s0.lower_bound(0) == s0.begin());
+            REQUIRE(s0.lower_bound(1) == s0.begin() + 1);
+            REQUIRE(s0.lower_bound(10) == s0.end());
+            REQUIRE(my_as_const(s0).lower_bound(-1) == s0.cbegin());
+            REQUIRE(my_as_const(s0).lower_bound(7) == s0.cbegin() + 3);
+        }
+    }
+    SECTION("observers") {
+        struct my_less {
+            int i;
+            my_less(int i) : i(i) {}
+            bool operator()(int l, int r) const {
+                return l < r;
+            }
+        };
+        using set_t = flat_set<int, my_less>;
+        set_t s0(my_less(42));
+        REQUIRE(my_as_const(s0).key_comp().i == 42);
+        REQUIRE(my_as_const(s0).value_comp().i == 42);
+    }
+    SECTION("operators") {
+        using set_t = flat_set<int>;
+
+        REQUIRE(set_t{1,2,3} == set_t{3,2,1});
+        REQUIRE_FALSE(set_t{1,2,3} == set_t{3,2,4});
+        REQUIRE_FALSE(set_t{1,2,3} == set_t{1,2,3,4});
+
+        REQUIRE(set_t{1,2,3} != set_t{3,2,4});
+        REQUIRE_FALSE(set_t{1,2,3} != set_t{3,2,1});
+
+        REQUIRE(set_t{2,3,4,6} < set_t{2,3,5});
+        REQUIRE(set_t{2,3,4,6} <= set_t{2,3,5});
+        REQUIRE_FALSE(set_t{2,3,5} < set_t{2,3,4,6});
+        REQUIRE_FALSE(set_t{2,3,5} <= set_t{2,3,4,6});
+
+        REQUIRE_FALSE(set_t{2,3,4,6} > set_t{2,3,5});
+        REQUIRE_FALSE(set_t{2,3,4,6} >= set_t{2,3,5});
+        REQUIRE(set_t{2,3,5} > set_t{2,3,4,6});
+        REQUIRE(set_t{2,3,5} >= set_t{2,3,4,6});
+
+        REQUIRE_FALSE(set_t{1,2,3} < set_t{1,2,3});
+        REQUIRE(set_t{1,2,3} <= set_t{1,2,3});
+        REQUIRE_FALSE(set_t{1,2,3} > set_t{1,2,3});
+        REQUIRE(set_t{1,2,3} >= set_t{1,2,3});
+    }
 }