flat_segment_tree.hpp

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#ifndef INCLUDED_MDDS_FLAT_SEGMENT_TREE_HPP
#define INCLUDED_MDDS_FLAT_SEGMENT_TREE_HPP

#include <iostream>
#include <sstream>
#include <utility>
#include <cassert>

#include "mdds/node.hpp"
#include "mdds/flat_segment_tree_itr.hpp"
#include "mdds/global.hpp"

#ifdef MDDS_UNIT_TEST
#include <cstdio>
#include <vector>
#endif

namespace mdds {

template<typename _Key, typename _Value>
class flat_segment_tree
{
public:
    typedef _Key    key_type;
    typedef _Value  value_type;
    typedef size_t  size_type;

    struct nonleaf_value_type
    {
        key_type low;   
        key_type high;  

        bool operator== (const nonleaf_value_type& r) const
        {
            return low == r.low && high == r.high;
        }
    
        nonleaf_value_type()
            : low(0)
            , high(0)
        {
        }
    };

    struct leaf_value_type
    {
        key_type    key;
        value_type  value;
        
        bool operator== (const leaf_value_type& r) const
        {
            return key == r.key && value == r.value;
        }

        leaf_value_type()
            : key(0)
            , value()
        {
        }
    };

    // Handlers required by the node template class.
    struct fill_nonleaf_value_handler;
    struct init_handler;
    struct dispose_handler;
#ifdef MDDS_UNIT_TEST
    struct to_string_handler;
#endif

    typedef __st::node<flat_segment_tree> node;
    typedef typename node::node_ptr node_ptr;

    typedef __st::nonleaf_node<flat_segment_tree> nonleaf_node;

    struct fill_nonleaf_value_handler
    {
        void operator() (__st::nonleaf_node<flat_segment_tree>& _self, const __st::node_base* left_node, const __st::node_base* right_node)
        {
            // Parent node should carry the range of all of its child nodes.
            if (left_node)
            {
                _self.value_nonleaf.low =
                    left_node->is_leaf ?
                        static_cast<const node*>(left_node)->value_leaf.key :
                        static_cast<const nonleaf_node*>(left_node)->value_nonleaf.low;
            }
            else
            {
                // Having a left node is prerequisite.
                throw general_error("flat_segment_tree::fill_nonleaf_value_handler: Having a left node is prerequisite.");
            }

            if (right_node)
            {    
                if (right_node->is_leaf)
                {
                    // When the child nodes are leaf nodes, the upper bound
                    // must be the value of the node that comes after the
                    // right leaf node (if such node exists).
                    const node* p = static_cast<const node*>(right_node);
                    if (p->next)
                        _self.value_nonleaf.high = p->next->value_leaf.key;
                    else
                        _self.value_nonleaf.high = p->value_leaf.key;
                }
                else
                {
                    _self.value_nonleaf.high = static_cast<const nonleaf_node*>(right_node)->value_nonleaf.high;
                }
            }
            else
            {
                _self.value_nonleaf.high =
                    left_node->is_leaf ?
                    static_cast<const node*>(left_node)->value_leaf.key :
                    static_cast<const nonleaf_node*>(left_node)->value_nonleaf.high;
            }
        }
    };

#ifdef MDDS_UNIT_TEST
    struct to_string_handler
    {
        std::string operator() (const node& _self) const
        {
            std::ostringstream os;
            os << "(" << _self.value_leaf.key << ") ";
            return os.str();
        }

        std::string operator() (const mdds::__st::nonleaf_node<flat_segment_tree>& _self) const
        {
            std::ostringstream os;
            os << "(" << _self.value_nonleaf.low << "-" << _self.value_nonleaf.high << ") ";
            return os.str();
        }
    };
#endif

    struct init_handler
    {
        void operator() (node& /*_self*/) {}
        void operator() (__st::nonleaf_node<flat_segment_tree>& /*_self*/) {}
    };

    struct dispose_handler
    {
        void operator() (node& /*_self*/) {}
        void operator() (__st::nonleaf_node<flat_segment_tree>& /*_self*/) {}
    };

private:

    friend struct ::mdds::__fst::itr_forward_handler<flat_segment_tree>;
    friend struct ::mdds::__fst::itr_reverse_handler<flat_segment_tree>;

public:
    class const_iterator : public ::mdds::__fst::const_iterator_base<
        flat_segment_tree, ::mdds::__fst::itr_forward_handler<flat_segment_tree> > 
    {
        typedef ::mdds::__fst::const_iterator_base<
            flat_segment_tree, ::mdds::__fst::itr_forward_handler<flat_segment_tree> > 
                base_type;
        friend class flat_segment_tree;
    public:
        const_iterator() :
            base_type(nullptr, false) {}

    private:
        explicit const_iterator(const typename base_type::fst_type* _db, bool _end) :
            base_type(_db, _end) {}

        explicit const_iterator(const typename base_type::fst_type* _db, const node* p) :
            base_type(_db, p) {}
    };

    class const_reverse_iterator : public ::mdds::__fst::const_iterator_base<
        flat_segment_tree, ::mdds::__fst::itr_reverse_handler<flat_segment_tree> > 
    {
        typedef ::mdds::__fst::const_iterator_base<
            flat_segment_tree, ::mdds::__fst::itr_reverse_handler<flat_segment_tree> > 
                base_type;
        friend class flat_segment_tree;
    public:
        const_reverse_iterator() :
            base_type(nullptr, false) {}
    private:
        explicit const_reverse_iterator(const typename base_type::fst_type* _db, bool _end) : 
            base_type(_db, _end) {}
    };

    using const_segment_iterator = mdds::__fst::const_segment_iterator<flat_segment_tree>;

    const_iterator begin() const
    {
        return const_iterator(this, false);
    }

    const_iterator end() const
    {
        return const_iterator(this, true);
    }

    const_reverse_iterator rbegin() const
    {
        return const_reverse_iterator(this, false);
    }

    const_reverse_iterator rend() const
    {
        return const_reverse_iterator(this, true);
    }

    const_segment_iterator begin_segment() const;

    const_segment_iterator end_segment() const;

    flat_segment_tree(key_type min_val, key_type max_val, value_type init_val);

    flat_segment_tree(const flat_segment_tree<key_type, value_type>& r);

    ~flat_segment_tree();

    flat_segment_tree<key_type, value_type>&
    operator=(const flat_segment_tree<key_type, value_type>& other);

    void swap(flat_segment_tree<key_type, value_type>& other);

    void clear();

    std::pair<const_iterator, bool>
    insert_front(key_type start_key, key_type end_key, value_type val)
    {
        return insert_segment_impl(start_key, end_key, val, true);
    }

    std::pair<const_iterator, bool>
    insert_back(key_type start_key, key_type end_key, value_type val)
    {
        return insert_segment_impl(start_key, end_key, val, false);
    }

    std::pair<const_iterator, bool>
    insert(const const_iterator& pos, key_type start_key, key_type end_key, value_type val);

    void shift_left(key_type start_key, key_type end_key);

    void shift_right(key_type pos, key_type size, bool skip_start_node);

    std::pair<const_iterator, bool>
    search(key_type key, value_type& value, key_type* start_key = nullptr, key_type* end_key = nullptr) const;

    std::pair<const_iterator, bool>
    search(const const_iterator& pos, key_type key, value_type& value, key_type* start_key = nullptr, key_type* end_key = nullptr) const;

    std::pair<const_iterator, bool>
    search_tree(key_type key, value_type& value, key_type* start_key = nullptr, key_type* end_key = nullptr) const;

    void build_tree();

    bool is_tree_valid() const
    {
        return m_valid_tree;
    }

    bool operator==(const flat_segment_tree<key_type, value_type>& r) const;

    bool operator !=(const flat_segment_tree<key_type, value_type>& r) const
    {
        return !operator==(r);
    }

    key_type min_key() const
    {
        return m_left_leaf->value_leaf.key;
    }

    key_type max_key() const
    {
        return m_right_leaf->value_leaf.key;
    }

    value_type default_value() const
    {
        return m_init_val;
    }

    size_type leaf_size() const;

#ifdef MDDS_UNIT_TEST
    nonleaf_node* get_root_node() const
    {
        return m_root_node;
    }

    void dump_tree() const
    {
        using ::std::cout;
        using ::std::endl;

        if (!m_valid_tree)
            assert(!"attempted to dump an invalid tree!");

        size_t node_count = mdds::__st::tree_dumper<node, nonleaf_node>::dump(m_root_node);
        size_t node_instance_count = node::get_instance_count();
        size_t leaf_count = leaf_size();

        cout << "tree node count = " << node_count << "; node instance count = "
            << node_instance_count << "; leaf node count = " << leaf_count << endl;

        assert(leaf_count == node_instance_count);
    }

    void dump_leaf_nodes() const
    {
        using ::std::cout;
        using ::std::endl;

        cout << "------------------------------------------" << endl;

        node_ptr cur_node = m_left_leaf;
        long node_id = 0;
        while (cur_node)
        {
            cout << "  node " << node_id++ << ": key = " << cur_node->value_leaf.key
                << "; value = " << cur_node->value_leaf.value 
                << endl;
            cur_node = cur_node->next;
        }
        cout << endl << "  node instance count = " << node::get_instance_count() << endl;
    }

    bool verify_keys(const ::std::vector<key_type>& key_values) const
    {
        {
            // Start from the left-most node, and traverse right.
            node* cur_node = m_left_leaf.get();
            typename ::std::vector<key_type>::const_iterator itr = key_values.begin(), itr_end = key_values.end();
            for (; itr != itr_end; ++itr)
            {
                if (!cur_node)
                    // Position past the right-mode node.  Invalid.
                    return false;
    
                if (cur_node->value_leaf.key != *itr)
                    // Key values differ.
                    return false;
    
                cur_node = cur_node->next.get();
            }

            if (cur_node)
                // At this point, we expect the current node to be at the position
                // past the right-most node, which is nullptr.
                return false;
        }

        {
            // Start from the right-most node, and traverse left.
            node* cur_node = m_right_leaf.get();
            typename ::std::vector<key_type>::const_reverse_iterator itr = key_values.rbegin(), itr_end = key_values.rend();
            for (; itr != itr_end; ++itr)
            {
                if (!cur_node)
                    // Position past the left-mode node.  Invalid.
                    return false;
    
                if (cur_node->value_leaf.key != *itr)
                    // Key values differ.
                    return false;
    
                cur_node = cur_node->prev.get();
            }

            if (cur_node)
                // Likewise, we expect the current position to be past the
                // left-most node, in which case the node value is nullptr.
                return false;
        }
        
        return true;
    }

    bool verify_values(const ::std::vector<value_type>& values) const
    {
        node* cur_node = m_left_leaf.get();
        node* end_node = m_right_leaf.get();
        typename ::std::vector<value_type>::const_iterator itr = values.begin(), itr_end = values.end();
        for (; itr != itr_end; ++itr)
        {
            if (cur_node == end_node || !cur_node)
                return false;

            if (cur_node->value_leaf.value != *itr)
                // Key values differ.
                return false;

            cur_node = cur_node->next.get();
        }

        if (cur_node != end_node)
            // At this point, we expect the current node to be at the end of 
            // range.
            return false;

        return true;
    }
#endif

private:
    flat_segment_tree(); // default constructor is not allowed.

    void append_new_segment(key_type start_key)
    {
        if (m_right_leaf->prev->value_leaf.key == start_key)
        {
            m_right_leaf->prev->value_leaf.value = m_init_val;
            return;
        }

#ifdef MDDS_UNIT_TEST
        // The start position must come after the position of the last node 
        // before the right-most node.
        assert(m_right_leaf->prev->value_leaf.key < start_key);
#endif

        if (m_right_leaf->prev->value_leaf.value == m_init_val)
            // The existing segment has the same value.  No need to insert a 
            // new segment.
            return;

        node_ptr new_node(new node);
        new_node->value_leaf.key   = start_key;
        new_node->value_leaf.value = m_init_val;
        new_node->prev = m_right_leaf->prev;
        new_node->next = m_right_leaf;
        m_right_leaf->prev->next = new_node;
        m_right_leaf->prev = new_node;
        m_valid_tree = false;
    }

    ::std::pair<const_iterator, bool>
        insert_segment_impl(key_type start_key, key_type end_key, value_type val, bool forward);

    ::std::pair<const_iterator, bool>
        insert_to_pos(node_ptr& start_pos, key_type start_key, key_type end_key, value_type val);

    ::std::pair<const_iterator, bool>
        search_impl(const node* pos, key_type key, value_type& value, key_type* start_key, key_type* end_key) const;

    const node* get_insertion_pos_leaf_reverse(key_type key, const node* start_pos) const;

    const node* get_insertion_pos_leaf(key_type key, const node* start_pos) const;

    static void shift_leaf_key_left(node_ptr& begin_node, node_ptr& end_node, key_type shift_value)
    {
        node* cur_node_p = begin_node.get();
        node* end_node_p = end_node.get();
        while (cur_node_p != end_node_p)
        {
            cur_node_p->value_leaf.key -= shift_value;
            cur_node_p = cur_node_p->next.get();
        }
    }

    static void shift_leaf_key_right(node_ptr& cur_node, node_ptr& end_node, key_type shift_value)
    {
        key_type end_node_key = end_node->value_leaf.key;
        while (cur_node.get() != end_node.get())
        {
            cur_node->value_leaf.key += shift_value;
            if (cur_node->value_leaf.key < end_node_key)
            {
                // The node is still in-bound.  Keep shifting.
                cur_node = cur_node->next;
                continue;
            }

            // This node has been pushed outside the end node position.
            // Remove all nodes that follows, and connect the previous node
            // with the end node.

            node_ptr last_node = cur_node->prev;
            while (cur_node.get() != end_node.get())
            {
                node_ptr next_node = cur_node->next;
                disconnect_all_nodes(cur_node.get());
                cur_node = next_node;
            }
            last_node->next = end_node;
            end_node->prev = last_node;
            return;
        }
    }

    void destroy();

    bool adjust_segment_range(key_type& start_key, key_type& end_key) const;

private:
    std::vector<nonleaf_node> m_nonleaf_node_pool;

    nonleaf_node* m_root_node;
    node_ptr   m_left_leaf;
    node_ptr   m_right_leaf;
    value_type m_init_val;
    bool       m_valid_tree;
};

template<typename _Key, typename _Value>
void
swap(flat_segment_tree<_Key, _Value>& left, flat_segment_tree<_Key, _Value>& right)
{
    left.swap(right);
}

} // namespace mdds

#include "flat_segment_tree_def.inl"

#endif

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