trie_map.hpp

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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 *
 * Copyright (c) 2015 Kohei Yoshida
 *
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 * obtaining a copy of this software and associated documentation
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 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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 * OTHER DEALINGS IN THE SOFTWARE.
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 ************************************************************************/

#ifndef INCLUDED_MDDS_TRIE_MAP_HPP
#define INCLUDED_MDDS_TRIE_MAP_HPP

#include <vector>
#include <string>
#include <deque>
#include <map>

namespace mdds {

namespace trie {

struct std_string_trait
{
    typedef std::string string_type;

    typedef std::string buffer_type;

    typedef char char_type;

    static buffer_type init_buffer(const char_type* str, size_t length)
    {
        return buffer_type(str, length);
    }

    static void push_back(buffer_type& buffer, char_type c)
    {
        buffer.push_back(c);
    }

    static void pop_back(buffer_type& buffer)
    {
        buffer.pop_back();
    }

    static string_type to_string(const buffer_type& buf)
    {
        return buf;
    }
};

}

template<typename _KeyTrait, typename _ValueT>
class packed_trie_map;

template<typename _KeyTrait, typename _ValueT>
class trie_map
{
    friend class packed_trie_map<_KeyTrait, _ValueT>;

public:
    typedef packed_trie_map<_KeyTrait, _ValueT> packed_type;
    typedef _KeyTrait key_trait_type;
    typedef typename key_trait_type::string_type string_type;
    typedef typename key_trait_type::buffer_type buffer_type;
    typedef typename key_trait_type::char_type   char_type;
    typedef _ValueT value_type;
    typedef size_t size_type;
    typedef std::pair<string_type, value_type> key_value_type;

private:

    struct trie_node
    {
        typedef std::map<char_type, trie_node> children_type;

        children_type children;
        value_type value;
        bool has_value;

        trie_node() : has_value(false) {}
    };

public:

    trie_map() = delete;

    trie_map(value_type null_value);

    void insert(const char_type* key, size_type len, const value_type& value);

    bool erase(const char_type* key, size_type len);

    value_type find(const char_type* input, size_type len) const;

    std::vector<key_value_type> prefix_search(const char_type* prefix, size_type len) const;

    size_type size() const;

    void clear();

    packed_type pack() const;

private:
    void insert_into_tree(
        trie_node& node, const char_type* key, const char_type* key_end, const value_type& value);

    const trie_node* find_prefix_node(
        const trie_node& node, const char_type* prefix, const char_type* prefix_end) const;

    void fill_child_node_items(
        std::vector<key_value_type>& items, buffer_type& buffer, const trie_node& node) const;

    void count_values(size_type& n, const trie_node& node) const;

private:
    value_type m_null_value;
    trie_node m_root;
};

template<typename _KeyTrait, typename _ValueT>
class packed_trie_map
{
public:
    typedef _KeyTrait key_trait_type;
    typedef typename key_trait_type::string_type string_type;
    typedef typename key_trait_type::buffer_type buffer_type;
    typedef typename key_trait_type::char_type   char_type;
    typedef _ValueT value_type;
    typedef size_t size_type;
    typedef std::pair<string_type, value_type> key_value_type;

    struct entry
    {
        const char_type* key;
        size_type keylen;
        value_type value;

        entry(const char_type* _key, size_type _keylen, value_type _value) :
            key(_key), keylen(_keylen), value(_value) {}
    };

private:
    struct trie_node
    {
        char_type key;
        const value_type* value;

        std::deque<trie_node*> children;

        trie_node(char_type _key) : key(_key), value(nullptr) {}
    };

    typedef std::deque<trie_node> node_pool_type;
    typedef std::vector<uintptr_t> packed_type;
    typedef std::deque<value_type> value_store_type;
    typedef std::vector<std::tuple<size_t, char_type>> child_offsets_type;

public:

    packed_trie_map() = delete;

    packed_trie_map(const entry* entries, size_type entry_size, value_type null_value);

    packed_trie_map(const trie_map<key_trait_type, value_type>& other);

    value_type find(const char_type* input, size_type len) const;

    std::vector<key_value_type> prefix_search(const char_type* prefix, size_type len) const;

    size_type size() const;

private:
    void traverse_range(
        trie_node& root, node_pool_type& node_pool, const entry* start, const entry* end,
        size_type pos);

    size_type compact_node(const trie_node& node);
    size_type compact_node(const typename trie_map<_KeyTrait, _ValueT>::trie_node& node);

    void push_child_offsets(size_type offset, const child_offsets_type& child_offsets);

    void compact(const trie_node& root);
    void compact(const typename trie_map<_KeyTrait, _ValueT>::trie_node& root);

    const uintptr_t* find_prefix_node(
        const uintptr_t* p, const char_type* prefix, const char_type* prefix_end) const;

    void fill_child_node_items(
        std::vector<key_value_type>& items, buffer_type& buffer, const uintptr_t* p) const;

#ifdef MDDS_TRIE_MAP_DEBUG
    void dump_node(buffer_type& buffer, const trie_node& node) const;
    void dump_trie(const trie_node& root) const;
    void dump_packed_trie(const std::vector<uintptr_t>& packed) const;
#endif

private:
    value_type m_null_value;
    size_type m_entry_size;

    value_store_type m_value_store;
    packed_type m_packed;
};

}

#include "trie_map_def.inl"

#endif

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