65 lines
2.0 KiB
C++
65 lines
2.0 KiB
C++
#ifndef DOUBLY_LINKED_LIST_H
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#define DOUBLY_LINKED_LIST_H
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#include <cassert>
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#include <cstddef>
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#include "queue.h"
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namespace seq
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{
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class DoublyLinkedListNode
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{
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public:
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// return a reference to the stored item
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int& get_item() { return this->item; }
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// return pointer to next node, or nullptr if this is the final node
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DoublyLinkedListNode* get_next() const { return this->next; }
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// return pointer to previous node, or nullptr if this is the initial node
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DoublyLinkedListNode* get_prev() const { return this->prev; }
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// overwrite the item stored in this node
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void set_item(int in_item) { this->item = in_item; }
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private:
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int item = 0;
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DoublyLinkedListNode* next = nullptr;
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DoublyLinkedListNode* prev = nullptr;
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// attach a node behind this node
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// if there was a node attached to this previously, it is NOT deleted!
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void set_next(DoublyLinkedListNode* in_next) { this->next = in_next; }
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// attach a node before this node
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// if there was a node attached to this previously, it is NOT deleted!
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void set_prev(DoublyLinkedListNode* in_prev) { this->prev = in_prev; }
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friend class DoublyLinkedList; // allow DoublyLinkedList to access private members
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};
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class DoublyLinkedList: public Queue
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{
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public:
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bool empty() const { return (this->head == nullptr); } // test whether the doubly linked list is empty
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size_t size() const; // return the size (number of items in the doubly linked list)
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void enqueue(int element);
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int dequeue();
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// return pointer to the head/tail node
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DoublyLinkedListNode* begin() const { return this->head; }
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DoublyLinkedListNode* end() const { return this->tail; }
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void clear() { while(!this->empty()) this->dequeue(); } // remove all the items from the list
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~DoublyLinkedList() { this->clear(); }
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private:
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DoublyLinkedListNode* head = nullptr;
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DoublyLinkedListNode* tail = nullptr;
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};
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}
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#endif
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