/*
 * Copyright 2004-2005 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.lang.mutable;

import org.apache.commons.lang.math.NumberUtils;

/**
 * A mutable <code>double</code> wrapper.
 * 
 * @see Double
 * @since 2.1
 * @version $Id: MutableDouble.java,v 1.1 2008/09/23 12:47:44 chm Exp $
 */
public class MutableDouble extends Number implements Comparable, Mutable {

    /** Serialization lock. */
    private static final long serialVersionUID = 1587163916L;

    /** The mutable value. */
    private double value;

    /**
     * Constructs a new MutableDouble with the default value of zero.
     */
    public MutableDouble() {
        super();
    }

    /**
     * Constructs a new MutableDouble with the specified value.
     * 
     * @param value
     *            a value.
     */
    public MutableDouble(double value) {
        super();
        this.value = value;
    }

    /**
     * Constructs a new MutableDouble with the specified value.
     * 
     * @param value
     *            a value.
     * @throws NullPointerException
     *             if the object is null
     */
    public MutableDouble(Number value) {
        super();
        this.value = value.doubleValue();
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the value as a Double instance.
     * 
     * @return the value as a Double
     */
    public Object getValue() {
        return new Double(this.value);
    }

    /**
     * Sets the value.
     * 
     * @param value
     *            the value to set
     */
    public void setValue(double value) {
        this.value = value;
    }

    /**
     * Sets the value from any Number instance.
     * 
     * @param value
     *            the value to set
     * @throws NullPointerException
     *             if the object is null
     * @throws ClassCastException
     *             if the type is not a {@link Number}
     */
    public void setValue(Object value) {
        setValue(((Number) value).doubleValue());
    }

    //-----------------------------------------------------------------------
    // shortValue and bytValue rely on Number implementation
    /**
     * Returns the value of this MutableDouble as a int.
     *
     * @return the numeric value represented by this object after conversion to type int.
     */
    public int intValue() {
        return (int) value;
    }

    /**
     * Returns the value of this MutableDouble as a long.
     *
     * @return the numeric value represented by this object after conversion to type long.
     */
    public long longValue() {
        return (long) value;
    }

    /**
     * Returns the value of this MutableDouble as a float.
     *
     * @return the numeric value represented by this object after conversion to type float.
     */
    public float floatValue() {
        return (float) value;
    }

    /**
     * Returns the value of this MutableDouble as a double.
     *
     * @return the numeric value represented by this object after conversion to type double.
     */
    public double doubleValue() {
        return value;
    }

    /**
     * Checks whether the double value is the special NaN value.
     * 
     * @return true if NaN
     */
    public boolean isNaN() {
        return Double.isNaN(value);
    }

    /**
     * Checks whether the double value is infinite.
     * 
     * @return true if infinite
     */
    public boolean isInfinite() {
        return Double.isInfinite(value);
    }

    //-----------------------------------------------------------------------
    /**
     * Compares this object against the specified object. The result is <code>true</code> if and only if the argument
     * is not <code>null</code> and is a <code>Double</code> object that represents a double that has the identical
     * bit pattern to the bit pattern of the double represented by this object. For this purpose, two
     * <code>double</code> values are considered to be the same if and only if the method
     * {@link Double#doubleToLongBits(double)}returns the same long value when applied to each.
     * <p>
     * Note that in most cases, for two instances of class <code>Double</code>,<code>d1</code> and <code>d2</code>,
     * the value of <code>d1.equals(d2)</code> is <code>true</code> if and only if <blockquote>
     * 
     * <pre>
     *   d1.doubleValue()&nbsp;== d2.doubleValue()
     * </pre>
     * 
     * </blockquote>
     * <p>
     * also has the value <code>true</code>. However, there are two exceptions:
     * <ul>
     * <li>If <code>d1</code> and <code>d2</code> both represent <code>Double.NaN</code>, then the
     * <code>equals</code> method returns <code>true</code>, even though <code>Double.NaN==Double.NaN</code> has
     * the value <code>false</code>.
     * <li>If <code>d1</code> represents <code>+0.0</code> while <code>d2</code> represents <code>-0.0</code>,
     * or vice versa, the <code>equal</code> test has the value <code>false</code>, even though
     * <code>+0.0==-0.0</code> has the value <code>true</code>. This allows hashtables to operate properly.
     * </ul>
     * 
     * @param obj
     *            the object to compare with.
     * @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
     */
    public boolean equals(Object obj) {
        return (obj instanceof MutableDouble)
            && (Double.doubleToLongBits(((MutableDouble) obj).value) == Double.doubleToLongBits(value));
    }

    /**
     * Returns a suitable hashcode for this mutable.
     * 
     * @return a suitable hashcode
     */
    public int hashCode() {
        long bits = Double.doubleToLongBits(value);
        return (int) (bits ^ (bits >>> 32));
    }

    /**
     * Compares this mutable to another in ascending order.
     * 
     * @param obj
     *            the mutable to compare to
     * @return negative if this is less, zero if equal, positive if greater
     * @throws ClassCastException if the argument is not a MutableDouble
     */
    public int compareTo(Object obj) {
        MutableDouble other = (MutableDouble) obj;
        double anotherVal = other.value;
        return NumberUtils.compare(value, anotherVal);
    }

    /**
     * Returns the String value of this mutable.
     * 
     * @return the mutable value as a string
     */
    public String toString() {
        return String.valueOf(value);
    }

}
