list_intern.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef COMMON_LIST_INTERN_H
#define COMMON_LIST_INTERN_H

#include "common/scummsys.h"

namespace Common {

template<typename T> class List;


namespace ListInternal {
    struct NodeBase {
        NodeBase *_prev = nullptr;
        NodeBase *_next = nullptr;

        constexpr NodeBase() = default;
        constexpr NodeBase(NodeBase *prev, NodeBase *next) : _prev(prev), _next(next) {}
    };

    template<typename T>
    struct Node : public NodeBase {
        T _data;

        Node(const T &x) : _data(x) {}
    };

    template<typename T> struct ConstIterator;

    template<typename T>
    struct Iterator {
        typedef Iterator<T> Self;
        typedef Node<T> *   NodePtr;
        typedef T &         ValueRef;
        typedef T *         ValuePtr;
        typedef T           ValueType;

        NodeBase *_node;

        Iterator() : _node(nullptr) {}
        explicit Iterator(NodeBase *node) : _node(node) {}

        // Prefix inc
        Self &operator++() {
            if (_node)
                _node = _node->_next;
            return *this;
        }
        // Postfix inc
        Self operator++(int) {
            Self tmp(_node);
            ++(*this);
            return tmp;
        }
        // Prefix dec
        Self &operator--() {
            if (_node)
                _node = _node->_prev;
            return *this;
        }
        // Postfix dec
        Self operator--(int) {
            Self tmp(_node);
            --(*this);
            return tmp;
        }
        ValueRef operator*() const {
            assert(_node);
            return static_cast<NodePtr>(_node)->_data;
        }
        ValuePtr operator->() const {
            return &(operator*());
        }

        bool operator==(const Self &x) const {
            return _node == x._node;
        }

        bool operator!=(const Self &x) const {
            return _node != x._node;
        }
    };

    template<typename T>
    struct ConstIterator {
        typedef ConstIterator<T>    Self;
        typedef const Node<T> * NodePtr;
        typedef const T &       ValueRef;
        typedef const T *       ValuePtr;

        const NodeBase *_node;

        ConstIterator() : _node(nullptr) {}
        explicit ConstIterator(const NodeBase *node) : _node(node) {}
        ConstIterator(const Iterator<T> &x) : _node(x._node) {}

        // Prefix inc
        Self &operator++() {
            if (_node)
                _node = _node->_next;
            return *this;
        }
        // Postfix inc
        Self operator++(int) {
            Self tmp(_node);
            ++(*this);
            return tmp;
        }
        // Prefix dec
        Self &operator--() {
            if (_node)
                _node = _node->_prev;
            return *this;
        }
        // Postfix dec
        Self operator--(int) {
            Self tmp(_node);
            --(*this);
            return tmp;
        }
        ValueRef operator*() const {
            assert(_node);
            return static_cast<NodePtr>(_node)->_data;
        }
        ValuePtr operator->() const {
            return &(operator*());
        }

        bool operator==(const Self &x) const {
            return _node == x._node;
        }

        bool operator!=(const Self &x) const {
            return _node != x._node;
        }
    };


    template<typename T>
    bool operator==(const Iterator<T>& a, const ConstIterator<T>& b) {
        return a._node == b._node;
    }

    template<typename T>
    bool operator!=(const Iterator<T>& a, const ConstIterator<T>& b) {
        return a._node != b._node;
    }
}


} // End of namespace Common

#endif