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#ifndef TRIE_TRIE_HPP
#define TRIE_TRIE_HPP

#include <algorithm>
#include <cassert>
#include <string>

template <typename Object, typename Key>
class Trie
{
    public:
        Trie()
            : node{nullptr}, size_{0}
        {
        }

        Trie(const Trie &rhs)
            : node(rhs.node ? std::shared_ptr<Node>(new Node(*rhs.node))
                            : nullptr),
              size_{rhs.size_}
        {
        }

        Trie(Trie &&trie)
            : Trie()
        {
            swap(*this, trie);
        }

        friend void
        swap(Trie &lhs, Trie &rhs)
        {
            using std::swap;
            swap(lhs.node, rhs.node);
            swap(lhs.size_, rhs.size_);
        }

        ~Trie()
        {
            std::cout << "~Trie()" << std::endl;
        }

        Trie &
        operator=(Trie rhs)
        {
            swap(*this, rhs);
            return *this;
        }

        Trie &
        insert(const std::string &key, const Object &obj)
        {
            recursive_insert(node, key.c_str(), obj);
            return *this;
        }

        std::size_t
        size() const
        {
            return size_;
        }

        template <typename Visitor>
        const Trie &
        visit(const std::string &key, const Visitor &visitor) const
        {
            recursive_visit(node, key.c_str(), visitor);
            return *this;
        }


    private:

        struct Node
        {
            Node()
                : node{}, object{}, hasObject{false}
            {
            }

            Node(const Object &value)
                : node{}, object{value}, hasObject{true}
            {
            }

            Node(const Node &rhs)
                : object{rhs.object}, hasObject{rhs.hasObject}
            {
                for (std::size_t i=0; i<Key::size(); ++i) {
                    node[i] = (rhs.node[i])
                            ? std::shared_ptr<Node>(new Node(*rhs.node[i]))
                            : nullptr;
                }
            }

            ~Node()
            {
                std::cout << "~Node()   ";
                if (hasObject) {
                    std::cout << "[" << object << "]" << std::endl;
                }
                std::cout << std::endl;
            }

            std::shared_ptr<Node>   node[Key::size()];
            Object                  object;
            bool                    hasObject;
        };

        void
        recursive_insert(std::shared_ptr<Node> &root,
                         const char *c, const Object &value)
        {
            if (!root) {
                root = std::shared_ptr<Node>(new Node());
            }

            if (*c) {
                std::size_t key = Key::map(*c);
                recursive_insert(root->node[key], c+1, value);
            } else {
                if (!root->hasObject) {
                    ++size_;
                }
                root->object    = value;
                root->hasObject = true;
            }
        }

        template <typename Visitor>
        void
        recursive_visit(std::shared_ptr<Node> root, const char *c,
                        const Visitor &visitor) const
        {
            if (!root) {
                return;
            }

            if (c && *c) {
                std::size_t key = Key::map(*c);
                recursive_visit(root->node[key], c+1, visitor);
            } else {
                if (root->hasObject) {
                    visitor(root->object);
                }
                for (std::size_t i=0; i<Key::size(); ++i) {
                    recursive_visit(root->node[i], nullptr, visitor);
                }
            }
        }

    public:
        class Pointer
        {
            public:
                Pointer(std::shared_ptr<Node> node = nullptr)
                    : node(node)
                {
                }

                bool
                defined() const
                {
                    return node!=nullptr;
                }

                bool
                exists() const
                {
                    assert(defined());
                    return node->hasObject;
                }

                bool
                canDescendAt(char c) const
                {
                    assert(defined());
                    return node->node[Key::map(c)] != nullptr;
                }

                bool
                descend(char c)
                {
                    assert(defined());
                    node = node->node[Key::map(c)];
                    return defined();
                }

                Object &
                operator*()
                {
                    assert(exists());
                    return node->object;
                }

                Object
                operator*() const
                {
                    assert(exists());
                    return node->object;
                }

                bool
                operator!=(const Pointer &other) const
                {
                    return node != other.node;
                }

                class Iterator
                {
                    public:
                        Iterator(Pointer pointer, std::size_t key = Key::size())
                            : pointer(pointer), key(key)
                        {
                            if (key<Key::size() &&
                               !pointer.canDescendAt(Key::unmap(key)))
                            {
                                ++*this;
                            }

                        }

                        bool
                        operator!=(const Iterator &other) const
                        {
                            if (key!=other.key) {
                                return true;
                            }
                            return pointer != other.pointer;
                        }

                        Iterator &
                        operator++()
                        {
                            assert(key<Key::size());

                            if (pointer.defined()) {
                                for(++key; key<Key::size(); ++key) {
                                    if (pointer.canDescendAt(Key::unmap(key))) {
                                        break;
                                    }
                                }
                            } else {
                                key = Key::size();
                            }
                            return *this;
                        }

                        char
                        operator*() const
                        {
                            return Key::unmap(key);
                        }

                    private:
                        Pointer     pointer;
                        std::size_t key;
                };

                Iterator
                begin() const
                {
                    return Iterator(node0);
                }

                Iterator
                end() const
                {
                    return Iterator(node);
                }

            private:
                std::shared_ptr<Node> node;

        };

        Pointer
        descend()
        {
            return Pointer(node);
        }

        std::shared_ptr<Node>   node;
        std::size_t             size_;


};

#endif // TRIE_TRIE_HPP