/*
 * @(#)Double.java	1.63 00/02/02
 *
 * Copyright 1994-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package java.lang;

/**
 * The Double class wraps a value of the primitive type
 * <code>double</code> in an object. An object of type
 * <code>Double</code> contains a single field whose type is
 * <code>double</code>.
 * <p>
 * In addition, this class provides several methods for converting a
 * <code>double</code> to a <code>String</code> and a
 * <code>String</code> to a <code>double</code>, as well as other
 * constants and methods useful when dealing with a
 * <code>double</code>.
 *
 * @author  Lee Boynton
 * @author  Arthur van Hoff
 * @version 1.63, 02/02/00
 * @since   JDK1.0
 */
public final class Double extends Number implements Comparable {
    /**
     * The positive infinity of type <code>double</code>. It is equal to
     * the value returned by 
     * <code>Double.longBitsToDouble(0x7ff0000000000000L)</code>.
     */
    public static final double POSITIVE_INFINITY = 1.0 / 0.0;

    /**
     * The negative infinity of type <code>double</code>. It is equal to
     * the value returned by 
     * <code>Double.longBitsToDouble(0xfff0000000000000L)</code>. 
     */
    public static final double NEGATIVE_INFINITY = -1.0 / 0.0;

    /** 
     * A Not-a-Number (NaN) value of type <code>double</code>. It is equal to
     * the value returned by 
     * <code>Double.longBitsToDouble(0x7ff8000000000000L)</code>.
     */
    public static final double NaN = 0.0d / 0.0;

    /**
     * The largest positive finite value of type <code>double</code>. 
     * It is equal to the returned by: 
     * <blockquote><pre>
     * <code>Double.longBitsToDouble(0x7fefffffffffffffL)</code>
     * </pre></blockquote>
     */
    public static final double MAX_VALUE = 1.79769313486231570e+308;

    /**
     * The smallest positive value of type <code>double</code>. It is 
     * equal to the value returned by 
     * <code>Double.longBitsToDouble(0x1L)</code>. 
     */
//  public static final double MIN_VALUE = 4.94065645841246544e-324;
    public static final double MIN_VALUE = longBitsToDouble(1L);

    /**
     * The Class object representing the primitive type double.
     *
     * @since   JDK1.1
     */
    public static final Class	TYPE = Class.getPrimitiveClass("double");

    /**
     * Creates a string representation of the <code>double</code> 
     * argument. All characters mentioned below are ASCII characters.
     * <ul>
     * <li>If the argument is NaN, the result is the string "NaN".
     * <li>Otherwise, the result is a string that represents the sign and 
     * magnitude (absolute value) of the argument. If the sign is negative, 
     * the first character of the result is '<code>-</code>' 
     * ('<code>\u002d</code>'); if the sign is positive, no sign character 
     * appears in the result. As for the magnitude <i>m</i>:
     * <li>If <i>m</i> is infinity, it is represented by the characters 
     * <code>"Infinity"</code> thus, positive infinity produces the result 
     * <code>"Infinity"</code> and negative infinity produces the result 
     * <code>"-Infinity"</code>.
     * <li>If <i>m</i> is zero, it is represented by the characters 
     * <code>"0.0"</code> thus, negative zero produces the result 
     * <code>"-0.0"</code> and positive zero produces the result 
     * <code>"0.0"</code>. 
     * <li>If <i>m</i> is greater than or equal to 10<sup>-3</sup> but less 
     * than 10<sup>7</sup>, then it is represented as the integer part of 
     * <i>m</i>, in decimal form with no leading zeroes, followed by 
     * <code>'.'</code> (<code>\u002E</code>), followed by one or more decimal
     * digits representing the fractional part of <i>m</i>. 
     * <li>If <i>m</i> is less than 10<sup>-3</sup> or not less than 
     * 10<sup>7</sup>, then it is represented in so-called "computerized 
     * scientific notation." Let <i>n</i> be the unique integer such that 
     * 10<sup>n</sup><=<i>m</i><10<sup>n+1</sup> then let <i>a</i> be 
     * the mathematically exact quotient of <i>m</i> and 10<sup>n</sup> so 
     * that 1<=<i>a</i><10. The magnitude is then represented as the 
     * integer part of <i>a</i>, as a single decimal digit, followed
     * by <code>'.'</code> (<code>\u002E</code>), followed by decimal digits 
     * representing the fractional part of <i>a</i>, followed by the letter 
     * <code>'E'</code> (<code>\u0045</code>), followed by a representation 
     * of <i>n</i> as a decimal integer, as produced by the method
     * {@link Integer#toString(int)}.
     * </ul><p>
     * How many digits must be printed for the fractional part of 
     * <i>m</i> or <i>a</i>? There must be at least one digit to represent 
     * the fractional part, and beyond that as many, but only as many, more 
     * digits as are needed to uniquely distinguish the argument value from
     * adjacent values of type <code>double</code>. That is, suppose that 
     * <i>x</i> is the exact mathematical value represented by the decimal 
     * representation produced by this method for a finite nonzero argument 
     * <i>d</i>. Then <i>d</i> must be the <code>double</code> value nearest 
     * to <i>x</i> or if two <code>double</code> values are equally close 
     * to <i>x</i>, then <i>d</i> must be one of them and the least
     * significant bit of the significand of <i>d</i> must be <code>0</code>.
     *
     * @param   d   the <code>double</code> to be converted.
     * @return  a string representation of the argument.
     */
    public static String toString(double d){
	return new FloatingDecimal(d).toJavaFormatString();
    }

    /**
     * Returns a new <code>Double</code> object initialized to the value 
     * represented by the specified string. The string <code>s</code> is 
     * interpreted as the representation of a floating-point value and a 
     * <code>Double</code> object representing that value is created and 
     * returned. 
     * <p>
     * If <code>s</code> is <code>null</code>, then a 
     * <code>NullPointerException</code> is thrown.
     * <p>
     * Leading and trailing whitespace characters in s are ignored. The rest 
     * of <code>s</code> should constitute a <i>FloatValue</i> as described 
     * by the lexical rule:
     * <blockquote><pre><i>
     * FloatValue:
     * 
     *        Sign<sub>opt</sub> FloatingPointLiteral
     * </i></pre></blockquote>
     * where <i>Sign</i> and <i>FloatingPointLiteral</i> are as defined in 
     * ?3.10.2 of the <a href="http://java.sun.com/docs/books/jls/html/">Java 
     * Language Specification</a>. If it does not have the form of a 
     * <i>FloatValue</i>, then a <code>NumberFormatException</code> is 
     * thrown. Otherwise, it is regarded as representing an exact decimal 
     * value in the usual "computerized scientific notation"; this exact 
     * decimal value is then conceptually converted to an "infinitely 
     * precise" binary value that is then rounded to type <code>double</code> 
     * by the usual round-to-nearest rule of IEEE 754 floating-point 
     * arithmetic. Finally, a new object of class <code>Double</code> is 
     * created to represent the <code>double</code> value. 
     *
     * @param      s   the string to be parsed.
     * @return     a newly constructed <code>Double</code> initialized to the
     *             value represented by the string argument.
     * @exception  NumberFormatException  if the string does not contain a
     *               parsable number.
     */
    public static Double valueOf(String s) throws NumberFormatException {
	return new Double(FloatingDecimal.readJavaFormatString(s).doubleValue());
    }

    /**
     * Returns a new double initialized to the value represented by the 
     * specified <code>String</code>, as performed by the <code>valueOf</code>
     * method of class <code>Double</code>.
     *
     * @param      s   the string to be parsed.
     * @return     the double value represented by the string argument.
     * @exception  NumberFormatException  if the string does not contain a
     *               parsable double.
     * @see        java.lang.Double#valueOf(String)
     * @since      1.2
     */
    public static double parseDouble(String s) throws NumberFormatException {
	return FloatingDecimal.readJavaFormatString(s).doubleValue();
    }

    /**
     * Returns true if the specified number is the special Not-a-Number (NaN)
     * value.
     *
     * @param   v   the value to be tested.
     * @return  <code>true</code> if the value of the argument is NaN;
     *          <code>false</code> otherwise.
     */
    static public boolean isNaN(double v) {
	return (v != v);
    }

    /**
     * Returns true if the specified number is infinitely large in magnitude.
     *
     * @param   v   the value to be tested.
     * @return  <code>true</code> if the value of the argument is positive
     *          infinity or negative infinity; <code>false</code> otherwise.
     */
    static public boolean isInfinite(double v) {
	return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
    }

    /**
     * The value of the Double.
     *
     * @serial
     */
    private double value;

    /**
     * Constructs a newly allocated <code>Double</code> object that
     * represents the primitive <code>double</code> argument.
     *
     * @param   value   the value to be represented by the <code>Double</code>.
     */
    public Double(double value) {
	this.value = value;
    }

    /**
     * Constructs a newly allocated <code>Double</code> object that
     * represents the floating- point value of type <code>double</code>
     * represented by the string. The string is converted to a
     * <code>double</code> value as if by the <code>valueOf</code> method.
     *
     * @param      s   a string to be converted to a <code>Double</code>.
     * @exception  NumberFormatException  if the string does not contain a
     *               parsable number.
     * @see        java.lang.Double#valueOf(java.lang.String)
     */
    public Double(String s) throws NumberFormatException {
	// REMIND: this is inefficient
	this(valueOf(s).doubleValue());
    }

    /**
     * Returns true if this Double value is the special Not-a-Number (NaN)
     * value.
     *
     * @return  <code>true</code> if the value represented by this object is
     *          NaN; <code>false</code> otherwise.
     */
    public boolean isNaN() {
	return isNaN(value);
    }

    /**
     * Returns true if this Double value is infinitely large in magnitude.
     *
     * @return  <code>true</code> if the value represented by this object is
     *          positive infinity or negative infinity;
     *          <code>false</code> otherwise.
     */
    public boolean isInfinite() {
	return isInfinite(value);
    }

    /**
     * Returns a String representation of this Double object.
     * The primitive <code>double</code> value represented by this
     * object is converted to a string exactly as if by the method
     * <code>toString</code> of one argument.
     *
     * @return  a <code>String</code> representation of this object.
     * @see     java.lang.Double#toString(double)
     */
    public String toString() {
	return String.valueOf(value);
    }

    /**
     * Returns the value of this Double as a byte (by casting to a byte).
     *
     * @since   JDK1.1
     */
    public byte byteValue() {
	return (byte)value;
    }

    /**
     * Returns the value of this Double as a short (by casting to a short).
     *
     * @since   JDK1.1
     */
    public short shortValue() {
	return (short)value;
    }

    /**
     * Returns the integer value of this Double (by casting to an int).
     *
     * @return  the <code>double</code> value represented by this object is
     *          converted to type <code>int</code> and the result of the
     *          conversion is returned.
     */
    public int intValue() {
	return (int)value;
    }

    /**
     * Returns the long value of this Double (by casting to a long).
     *
     * @return  the <code>double</code> value represented by this object is
     *          converted to type <code>long</code> and the result of the
     *          conversion is returned.
     */
    public long longValue() {
	return (long)value;
    }

    /**
     * Returns the float value of this Double.
     *
     * @return  the <code>double</code> value represented by this object is
     *          converted to type <code>float</code> and the result of the
     *          conversion is returned.
     * @since   JDK1.0     
     */
    public float floatValue() {
	return (float)value;
    }

    /**
     * Returns the double value of this Double.
     *
     * @return  the <code>double</code> value represented by this object.
     */
    public double doubleValue() {
	return (double)value;
    }

    /**
     * Returns a hashcode for this <code>Double</code> object. The result 
     * is the exclusive OR of the two halves of the long integer bit 
     * representation, exactly as produced by the method 
     * {@link #doubleToLongBits(double)}, of the primitive 
     * <code>double</code> value represented by this <code>Double</code> 
     * object. That is, the hashcode is the value of the expression: 
     * <blockquote><pre>
     * (int)(v^(v>>>32))
     * </pre></blockquote>
     * where <code>v</code> is defined by: 
     * <blockquote><pre>
     * long v = Double.doubleToLongBits(this.doubleValue());
     * </pre></blockquote>
     *
     * @return  a <code>hash code</code> value for this object.
     */
    public int hashCode() {
	long bits = doubleToLongBits(value);
	return (int)(bits ^ (bits >>> 32));
    }

    /**
     * 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 #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() == 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 Double)
	       && (doubleToLongBits(((Double)obj).value) ==
		      doubleToLongBits(value));
    }

    /**
     * Returns a representation of the specified floating-point value
     * according to the IEEE 754 floating-point "double
     * format" bit layout.
     * <p>
     * Bit 63 (the bit that is selected by the mask 
     * <code>0x8000000000000000L</code>) represents the sign of the 
     * floating-point number. Bits 
     * 62-52 (the bits that are selected by the mask 
     * <code>0x7ff0000000000000L</code>) represent the exponent. Bits 51-0 
     * (the bits that are selected by the mask 
     * <code>0x000fffffffffffffL</code>) represent the significand 
     * (sometimes called the mantissa) of the floating-point number. 
     * <p>
     * If the argument is positive infinity, the result is
     * <code>0x7ff0000000000000L</code>.
     * <p>
     * If the argument is negative infinity, the result is
     * <code>0xfff0000000000000L</code>.
     * <p>
     * If the argument is NaN, the result is 
     * <code>0x7ff8000000000000L</code>. 
     * <p>
     * In all cases, the result is a <code>long</code> integer that, when 
     * given to the {@link #longBitsToDouble(long)} method, will produce a 
     * floating-point value equal to the argument to 
     * <code>doubleToLongBits</code>.
     *
     * @param   value   a double precision floating-point number.
     * @return  the bits that represent the floating-point number.
     */
    public static native long doubleToLongBits(double value);

    /**
     * Returns a representation of the specified floating-point value
     * according to the IEEE 754 floating-point "double
     * format" bit layout.
     * <p>
     * Bit 63 (the bit that is selected by the mask 
     * <code>0x8000000000000000L</code>) represents the sign of the 
     * floating-point number. Bits 
     * 62-52 (the bits that are selected by the mask 
     * <code>0x7ff0000000000000L</code>) represent the exponent. Bits 51-0 
     * (the bits that are selected by the mask 
     * <code>0x000fffffffffffffL</code>) represent the significand 
     * (sometimes called the mantissa) of the floating-point number. 
     * <p>
     * If the argument is positive infinity, the result is
     * <code>0x7ff0000000000000L</code>.
     * <p>
     * If the argument is negative infinity, the result is
     * <code>0xfff0000000000000L</code>.
     * <p>
     * If the argument is NaN, the result is the <code>long</code> integer
     * representing the actual NaN value.  Unlike the <code>doubleToLongBits</code>
     * method, <code>doubleToRawLongBits</code> does not collapse NaN values.
     * <p>
     * In all cases, the result is a <code>long</code> integer that, when 
     * given to the {@link #longBitsToDouble(long)} method, will produce a 
     * floating-point value equal to the argument to 
     * <code>doubleToRawLongBits</code>.
     *
     * @param   value   a double precision floating-point number.
     * @return  the bits that represent the floating-point number.
     */
    public static native long doubleToRawLongBits(double value);

    /**
     * Returns the double-float corresponding to a given bit represention.
     * The argument is considered to be a representation of a
     * floating-point value according to the IEEE 754 floating-point
     * "double precision" bit layout. That floating-point
     * value is returned as the result.
     * <p>
     * If the argument is <code>0x7ff0000000000000L</code>, the result 
     * is positive infinity. 
     * <p>
     * If the argument is <code>0xfff0000000000000L</code>, the result 
     * is negative infinity. 
     * <p>
     * If the argument is any value in the range 
     * <code>0x7ff0000000000001L</code> through 
     * <code>0x7fffffffffffffffL</code> or in the range 
     * <code>0xfff0000000000001L</code> through 
     * <code>0xffffffffffffffffL</code>, the result is NaN. All IEEE 754 
     * NaN values of type <code>double</code> are, in effect, lumped together
     * by the Java programming language into a single value called NaN.
     * Distinct values of NaN are only accessible by use of the
     * <code>Double.doubleToRawLongBits</code> method. 
     * <p>
     * In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three 
     * values that can be computed from the argument: 
     * <blockquote><pre>
     * int s = ((bits >> 63) == 0) ? 1 : -1;
     * int e = (int)((bits >> 52) & 0x7ffL);
     * long m = (e == 0) ?
     *                 (bits & 0xfffffffffffffL) << 1 :
     *                 (bits & 0xfffffffffffffL) | 0x10000000000000L;
     * </pre></blockquote>
     * Then the floating-point result equals the value of the mathematical 
     * expression <i>s</i>·<i>m</i>·2<sup>e-1075</sup>.
     *
     * @param   bits   any <code>long</code> integer.
     * @return  the <code>double</code> floating-point value with the same
     *          bit pattern.
     */
    public static native double longBitsToDouble(long bits);

    /**
     * Compares two Doubles numerically.  There are two ways in which
     * comparisons performed by this method differ from those performed
     * by the Java language numerical comparison operators (<code><, <=,
     * ==, >= ></code>) when applied to primitive doubles:
     * <ul><li>
     *		<code>Double.NaN</code> is considered by this method to be
     *		equal to itself and greater than all other double values
     *		(including <code>Double.POSITIVE_INFINITY</code>).
     * <li>
     *		<code>0.0d</code> is considered by this method to be greater
     *		than <code>-0.0d</code>.
     * </ul>
     * This ensures that Double.compareTo(Object) (which inherits its behavior
     * from this method) obeys the general contract for Comparable.compareTo,
     * and that the <i>natural order</i> on Doubles is <i>total</i>.
     *
     * @param   anotherDouble   the <code>Double</code> to be compared.
     * @return  the value <code>0</code> if <code>anotherDouble</code> is
     *		numerically equal to this Double; a value less than
     *          <code>0</code> if this Double is numerically less than
     *		<code>anotherDouble</code> and a value greater than
     *		<code>0</code> if this Double is numerically greater than
     *		<code>anotherDouble</code>.
     *		
     * @since   1.2
     * @see     Comparable#compareTo(Object)
     */
    public int compareTo(Double anotherDouble) {
        double thisVal = value;
        double anotherVal = anotherDouble.value;

        if (thisVal < anotherVal)
            return -1;		 // Neither val is NaN, thisVal is smaller
        if (thisVal > anotherVal)
            return 1;		 // Neither val is NaN, thisVal is larger

        long thisBits = Double.doubleToLongBits(thisVal);
        long anotherBits = Double.doubleToLongBits(anotherVal);

        return (thisBits == anotherBits ?  0 : // Values are equal
                (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
                 1));                          // (0.0, -0.0) or (NaN, !NaN)
    }

    /**
     * Compares this Double to another Object.  If the Object is a Double,
     * this function behaves like <code>compareTo(Double)</code>.  Otherwise,
     * it throws a <code>ClassCastException</code> (as Doubles are comparable
     * only to other Doubles).
     *
     * @param   o the <code>Object</code> to be compared.
     * @return  the value <code>0</code> if the argument is a Double
     *		numerically equal to this Double; a value less than
     *		<code>0</code> if the argument is a Double numerically
     *		greater than this Double; and a value greater than
     *		<code>0</code> if the argument is a Double numerically
     *		less than this Double.
     * @exception <code>ClassCastException</code> if the argument is not a
     *		  <code>Double</code>.
     * @see     java.lang.Comparable
     * @since   1.2
     */
    public int compareTo(Object o) {
	return compareTo((Double)o);
    }

    /** use serialVersionUID from JDK 1.0.2 for interoperability */
    private static final long serialVersionUID = -9172774392245257468L;
}