156 lines
2.8 KiB
C++
156 lines
2.8 KiB
C++
/*
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* \brief List of double connected items
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* \author Martin Stein
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* \date 2012-11-30
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*/
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/*
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* Copyright (C) 2012-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _CORE__KERNEL__DOUBLE_LIST_H_
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#define _CORE__KERNEL__DOUBLE_LIST_H_
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namespace Kernel
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{
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/**
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* Ability to be an item in a double connected list
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*/
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template <typename T>
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class Double_list_item;
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/**
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* List of double connected items
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*/
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template <typename T>
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class Double_list;
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}
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template <typename T>
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class Kernel::Double_list_item
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{
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friend class Double_list<T>;
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private:
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Double_list_item * _next = nullptr;
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Double_list_item * _prev = nullptr;
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T & _payload;
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public:
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Double_list_item(T &payload) : _payload(payload) { }
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T &payload() { return _payload; }
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};
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template <typename T>
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class Kernel::Double_list
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{
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private:
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typedef Double_list_item<T> Item;
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Item * _head;
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Item * _tail;
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void _connect_neighbors(Item * const i)
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{
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i->_prev->_next = i->_next;
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i->_next->_prev = i->_prev;
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}
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void _to_tail(Item * const i)
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{
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if (i == _tail) { return; }
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_connect_neighbors(i);
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i->_prev = _tail;
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i->_next = 0;
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_tail->_next = i;
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_tail = i;
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}
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public:
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/**
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* Construct empty list
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*/
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Double_list() : _head(0), _tail(0) { }
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/**
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* Move item 'i' from its current list position to the tail
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*/
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void to_tail(Item * const i)
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{
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if (i == _head) { head_to_tail(); }
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else { _to_tail(i); }
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}
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/**
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* Insert item 'i' as new tail into list
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*/
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void insert_tail(Item * const i)
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{
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if (_tail) { _tail->_next = i; }
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else { _head = i; }
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i->_prev = _tail;
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i->_next = 0;
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_tail = i;
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}
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/**
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* Insert item 'i' as new head into list
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*/
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void insert_head(Item * const i)
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{
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if (_head) { _head->_prev = i; }
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else { _tail = i; }
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i->_next = _head;
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i->_prev = 0;
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_head = i;
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}
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/**
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* Remove item 'i' from list
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*/
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void remove(Item * const i)
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{
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if (i == _tail) { _tail = i->_prev; }
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else { i->_next->_prev = i->_prev; }
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if (i == _head) { _head = i->_next; }
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else { i->_prev->_next = i->_next; }
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}
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/**
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* Move head item of list to tail position
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*/
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void head_to_tail()
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{
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if (!_head || _head == _tail) { return; }
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_head->_prev = _tail;
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_tail->_next = _head;
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_head = _head->_next;
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_head->_prev = 0;
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_tail = _tail->_next;
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_tail->_next = 0;
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}
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/**
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* Call function 'f' of type 'void (Item *)' for each item in the list
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*/
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template <typename F> void for_each(F f) {
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for (Item * i = _head; i; i = i->_next) { f(i->payload()); } }
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/*
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* Accessors
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*/
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Item * head() const { return _head; }
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static Item * next(Item * const i) { return i->_next; }
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};
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#endif /* _CORE__KERNEL__DOUBLE_LIST_H_ */
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