/*

 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.vm.ci.meta;

/**

 * A profiled type that has a probability. Profiled types are naturally sorted in descending order

 * of their probabilities.

 */

public abstract class AbstractProfiledItem<T> implements Comparable<AbstractProfiledItem<?>> {

    protected final T item;

    protected final double probability;

    public AbstractProfiledItem(T item, double probability) {

        assert item != null;

        assert probability >= 0.0D && probability <= 1.0D;

        this.item = item;

        this.probability = probability;

    }

    protected T getItem() {

        return item;

    }

    /**

     * Returns the estimated probability of {@link #getItem()}.

     *

     * @return double value ≥ 0.0 and ≤ 1.0

     */

    public double getProbability() {

        return probability;

    }

    /**

     * Returns -1 if the {@linkplain #getProbability() probability} of this item is greater than

     * {@code o}'s probability, 0 if there are equal otherwise 1.

     */

    @Override

    public int compareTo(AbstractProfiledItem<?> o) {

        // Need to swap the order of operands so that higher probabilities are sorted first

        return Double.compare(o.getProbability(), getProbability());

    }

    @Override

    public int hashCode() {

        final int prime = 31;

        int result = 1;

        long temp;

        temp = Double.doubleToLongBits(probability);

        result = prime * result + (int) (temp ^ (temp >>> 32));

        result = prime * result + item.hashCode();

        return result;

    }

    @Override

    public boolean equals(Object obj) {

        if (this == obj) {

            return true;

        }

        if (obj == null) {

            return false;

        }

        if (getClass() != obj.getClass()) {

            return false;

        }

        AbstractProfiledItem<?> other = (AbstractProfiledItem<?>) obj;

        if (Double.doubleToLongBits(probability) != Double.doubleToLongBits(other.probability)) {

            return false;

        }

        return item.equals(other.item);

    }

    @Override

    public abstract String toString();

}