Class Cache

java/Chapter 10/Question10_7/Cache.java:5–95

import java.util.HashMap;

public class Cache {
	public static int MAX_SIZE = 10;
	public Node head;
	public Node tail;
	public HashMap<String, Node> map;
	public int size = 0;
	
	public Cache() {
		map = new HashMap<String, Node>();
	}
	
	public void moveToFront(Node node) {
		if (node == head) {
			return;
		}
		removeFromLinkedList(node);
		node.next = head;
		if (head != null) {
			head.prev = node;
		}
		head = node;
		size++;
		
		if (tail == null) {
			tail = node;
		}
	}
	
	public void moveToFront(String query) {
		Node node = map.get(query);
		moveToFront(node);
	}	
	
	public void removeFromLinkedList(Node node) {
		if (node == null) {
			return;
		}
		
		if (node.next != null || node.prev != null) {
			size--;
		}
		
		Node prev = node.prev;
		if (prev != null) {
			prev.next = node.next;
		} 
		
		Node next = node.next;
		if (next != null) {
			next.prev = prev;
		}
		
		if (node == head) {
			head = next;
		}
		
		if (node == tail) {
			tail = prev;