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Alternative VirtualFlows for JavaFX
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/*
 * Copyright (C) 2024 Parisi Alessandro - [email protected]
 * This file is part of VirtualizedFX (https://github.com/palexdev/VirtualizedFX)
 *
 * VirtualizedFX is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 3 of the License,
 * or (at your option) any later version.
 *
 * VirtualizedFX 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with VirtualizedFX. If not, see .
 */

package io.github.palexdev.virtualizedfx.utils;

import io.github.palexdev.mfxcore.collections.CircularQueue;
import io.github.palexdev.virtualizedfx.cells.base.VFXCell;

import java.util.Collection;
import java.util.LinkedList;

/**
 * A special kind of {@link LinkedList} which discards the oldest added item once it reaches the set capacity.
 * 
 * Basically the same as {@link CircularQueue}, but automatically invokes {@link C#dispose()} on cell that are discarded.
 */
public class CellsQueue> extends LinkedList {
	//================================================================================
	// Properties
	//================================================================================
	private int capacity;

	//================================================================================
	// Constructors
	//================================================================================
	public CellsQueue(int capacity) {
		super();
		this.capacity = capacity;
	}

	//================================================================================
	// Methods
	//================================================================================

	/**
	 * Adds the given cell to the queue. If at capacity, the oldest cell is disposed and discarded.
	 *
	 * @return whether the cell was added
	 */
	public boolean queue(C c) {
		if (capacity == 0) {
			// If cells cannot be cached because this is disabled (capacity = 0), they should be disposed
			c.dispose();
			return false;
		}
		if (super.size() == capacity) {
			C excess = super.remove();
			excess.dispose();
		}
		return super.add(c);
	}

	/**
	 * @return the queue's capacity, the maximum number of cells that can be added
	 */
	public int getCapacity() {
		return capacity;
	}

	/**
	 * Sets the queue's capacity. If the parameter is 0, every cell is disposed and removed. If the new capacity is
	 * lesser than the current one, then the oldest cell is removed until the capacity is reached.
	 */
	public void setCapacity(int capacity) {
		if (capacity == 0) {
			forEach(C::dispose);
			clear();
			this.capacity = capacity;
			return;
		}

		if (capacity < super.size()) {
			for (int i = 0; i < (super.size() - capacity); i++) {
				C excess = super.remove();
				excess.dispose();
			}
		}
		this.capacity = capacity;
	}

	//================================================================================
	// Overridden Methods
	//================================================================================
	@Override
	public boolean add(C c) {
		return queue(c);
	}

	@Override
	public boolean addAll(Collection cells) {
		boolean result = false;
		for (C c : cells) result |= add(c);
		return result;
	}
}