/*

 * Copyright 1994-2006 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.lang;

import sun.misc.FloatingDecimal;

import sun.misc.FpUtils;

import sun.misc.FloatConsts;

import sun.misc.DoubleConsts;

/**

 * The {@code Float} class wraps a value of primitive type

 * {@code float} in an object. An object of type

 * {@code Float} contains a single field whose type is

 * {@code float}.

 *

 * <p>In addition, this class provides several methods for converting a

 * {@code float} to a {@code String} and a

 * {@code String} to a {@code float}, as well as other

 * constants and methods useful when dealing with a

 * {@code float}.

 *

 * @author  Lee Boynton

 * @author  Arthur van Hoff

 * @author  Joseph D. Darcy

 * @since JDK1.0

 */

public final class Float extends Number implements Comparable<Float> {

    /**

     * A constant holding the positive infinity of type

     * {@code float}. It is equal to the value returned by

     * {@code Float.intBitsToFloat(0x7f800000)}.

     */

    public static final float POSITIVE_INFINITY = 1.0f / 0.0f;

    /**

     * A constant holding the negative infinity of type

     * {@code float}. It is equal to the value returned by

     * {@code Float.intBitsToFloat(0xff800000)}.

     */

    public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;

    /**

     * A constant holding a Not-a-Number (NaN) value of type

     * {@code float}.  It is equivalent to the value returned by

     * {@code Float.intBitsToFloat(0x7fc00000)}.

     */

    public static final float NaN = 0.0f / 0.0f;

    /**

     * A constant holding the largest positive finite value of type

     * {@code float}, (2-2<sup>-23</sup>)&middot;2<sup>127</sup>.

     * It is equal to the hexadecimal floating-point literal

     * {@code 0x1.fffffeP+127f} and also equal to

     * {@code Float.intBitsToFloat(0x7f7fffff)}.

     */

    public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f

    /**

     * A constant holding the smallest positive normal value of type

     * {@code float}, 2<sup>-126</sup>.  It is equal to the

     * hexadecimal floating-point literal {@code 0x1.0p-126f} and also

     * equal to {@code Float.intBitsToFloat(0x00800000)}.

     *

     * @since 1.6

     */

    public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f

    /**

     * A constant holding the smallest positive nonzero value of type

     * {@code float}, 2<sup>-149</sup>. It is equal to the

     * hexadecimal floating-point literal {@code 0x0.000002P-126f}

     * and also equal to {@code Float.intBitsToFloat(0x1)}.

     */

    public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f

    /**

     * Maximum exponent a finite {@code float} variable may have.  It

     * is equal to the value returned by {@code

     * Math.getExponent(Float.MAX_VALUE)}.

     *

     * @since 1.6

     */

    public static final int MAX_EXPONENT = 127;

    /**

     * Minimum exponent a normalized {@code float} variable may have.

     * It is equal to the value returned by {@code

     * Math.getExponent(Float.MIN_NORMAL)}.

     *

     * @since 1.6

     */

    public static final int MIN_EXPONENT = -126;

    /**

     * The number of bits used to represent a {@code float} value.

     *

     * @since 1.5

     */

    public static final int SIZE = 32;

    /**

     * The {@code Class} instance representing the primitive type

     * {@code float}.

     *

     * @since JDK1.1

     */

    public static final Class<Float> TYPE = Class.getPrimitiveClass("float");

    /**

     * Returns a string representation of the {@code float}

     * argument. All characters mentioned below are ASCII characters.

     * <ul>

     * <li>If the argument is NaN, the result is the string

     * "{@code 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>'&#92;u002D'</code>); if the sign is

     *     positive, no sign character appears in the result. As for

     *     the magnitude <i>m</i>:

     * <ul>

     * <li>If <i>m</i> is infinity, it is represented by the characters

     *     {@code "Infinity"}; thus, positive infinity produces

     *     the result {@code "Infinity"} and negative infinity

     *     produces the result {@code "-Infinity"}.

     * <li>If <i>m</i> is zero, it is represented by the characters

     *     {@code "0.0"}; thus, negative zero produces the result

     *     {@code "-0.0"} and positive zero produces the result

     *     {@code "0.0"}.

     * <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>'&#92;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 greater than or

     *      equal to 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><i>n</i> </sup>&le;

     *      <i>m</i> {@literal <} 10<sup><i>n</i>+1</sup>; then let <i>a</i>

     *      be the mathematically exact quotient of <i>m</i> and

     *      10<sup><i>n</i></sup> so that 1 &le; <i>a</i> {@literal <} 10.

     *      The magnitude is then represented as the integer part of

     *      <i>a</i>, as a single decimal digit, followed by

     *      '{@code .}' (<code>'&#92;u002E'</code>), followed by

     *      decimal digits representing the fractional part of

     *      <i>a</i>, followed by the letter '{@code E}'

     *      (<code>'&#92;u0045'</code>), followed by a representation

     *      of <i>n</i> as a decimal integer, as produced by the

     *      method {@link java.lang.Integer#toString(int)}.

     *

     * </ul>

     * </ul>

     * 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 float}. 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>f</i>. Then <i>f</i> must be the {@code float}

     * value nearest to <i>x</i>; or, if two {@code float} values are

     * equally close to <i>x</i>, then <i>f</i> must be one of

     * them and the least significant bit of the significand of

     * <i>f</i> must be {@code 0}.

     *

     * <p>To create localized string representations of a floating-point

     * value, use subclasses of {@link java.text.NumberFormat}.

     *

     * @param   f   the float to be converted.

     * @return a string representation of the argument.

     */

    public static String toString(float f) {

        return new FloatingDecimal(f).toJavaFormatString();

    }

    /**

     * Returns a hexadecimal string representation of the

     * {@code float} argument. All characters mentioned below are

     * ASCII characters.

     *

     * <ul>

     * <li>If the argument is NaN, the result is the string

     *     "{@code 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>'&#92;u002D'</code>); if the sign is positive, no sign character

     * appears in the result. As for the magnitude <i>m</i>:

     *

     * <ul>

     * <li>If <i>m</i> is infinity, it is represented by the string

     * {@code "Infinity"}; thus, positive infinity produces the

     * result {@code "Infinity"} and negative infinity produces

     * the result {@code "-Infinity"}.

     *

     * <li>If <i>m</i> is zero, it is represented by the string

     * {@code "0x0.0p0"}; thus, negative zero produces the result

     * {@code "-0x0.0p0"} and positive zero produces the result

     * {@code "0x0.0p0"}.

     *

     * <li>If <i>m</i> is a {@code float} value with a

     * normalized representation, substrings are used to represent the

     * significand and exponent fields.  The significand is

     * represented by the characters {@code "0x1."}

     * followed by a lowercase hexadecimal representation of the rest

     * of the significand as a fraction.  Trailing zeros in the

     * hexadecimal representation are removed unless all the digits

     * are zero, in which case a single zero is used. Next, the

     * exponent is represented by {@code "p"} followed

     * by a decimal string of the unbiased exponent as if produced by

     * a call to {@link Integer#toString(int) Integer.toString} on the

     * exponent value.

     *

     * <li>If <i>m</i> is a {@code float} value with a subnormal

     * representation, the significand is represented by the

     * characters {@code "0x0."} followed by a

     * hexadecimal representation of the rest of the significand as a

     * fraction.  Trailing zeros in the hexadecimal representation are

     * removed. Next, the exponent is represented by

     * {@code "p-126"}.  Note that there must be at

     * least one nonzero digit in a subnormal significand.

     *

     * </ul>

     *

     * </ul>

     *

     * <table border>

     * <caption><h3>Examples</h3></caption>

     * <tr><th>Floating-point Value</th><th>Hexadecimal String</th>

     * <tr><td>{@code 1.0}</td> <td>{@code 0x1.0p0}</td>

     * <tr><td>{@code -1.0}</td>        <td>{@code -0x1.0p0}</td>

     * <tr><td>{@code 2.0}</td> <td>{@code 0x1.0p1}</td>

     * <tr><td>{@code 3.0}</td> <td>{@code 0x1.8p1}</td>

     * <tr><td>{@code 0.5}</td> <td>{@code 0x1.0p-1}</td>

     * <tr><td>{@code 0.25}</td>        <td>{@code 0x1.0p-2}</td>

     * <tr><td>{@code Float.MAX_VALUE}</td>

     *     <td>{@code 0x1.fffffep127}</td>

     * <tr><td>{@code Minimum Normal Value}</td>

     *     <td>{@code 0x1.0p-126}</td>

     * <tr><td>{@code Maximum Subnormal Value}</td>

     *     <td>{@code 0x0.fffffep-126}</td>

     * <tr><td>{@code Float.MIN_VALUE}</td>

     *     <td>{@code 0x0.000002p-126}</td>

     * </table>

     * @param   f   the {@code float} to be converted.

     * @return a hex string representation of the argument.

     * @since 1.5

     * @author Joseph D. Darcy

     */

    public static String toHexString(float f) {

        if (Math.abs(f) < FloatConsts.MIN_NORMAL

            &&  f != 0.0f ) {// float subnormal

            // Adjust exponent to create subnormal double, then

            // replace subnormal double exponent with subnormal float

            // exponent

            String s = Double.toHexString(FpUtils.scalb((double)f,

                                                        /* -1022+126 */

                                                        DoubleConsts.MIN_EXPONENT-

                                                        FloatConsts.MIN_EXPONENT));

            return s.replaceFirst("p-1022$", "p-126");

        }

        else // double string will be the same as float string

            return Double.toHexString(f);

    }

    /**

     * Returns a {@code Float} object holding the

     * {@code float} value represented by the argument string

     * {@code s}.

     *

     * <p>If {@code s} is {@code null}, then a

     * {@code NullPointerException} is thrown.

     *

     * <p>Leading and trailing whitespace characters in {@code s}

     * are ignored.  Whitespace is removed as if by the {@link

     * String#trim} method; that is, both ASCII space and control

     * characters are removed. The rest of {@code s} should

     * constitute a <i>FloatValue</i> as described by the lexical

     * syntax rules:

     *

     * <blockquote>

     * <dl>

     * <dt><i>FloatValue:</i>

     * <dd><i>Sign<sub>opt</sub></i> {@code NaN}

     * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}

     * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>

     * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>

     * <dd><i>SignedInteger</i>

     * </dl>

     *

     * <p>

     *

     * <dl>

     * <dt><i>HexFloatingPointLiteral</i>:

     * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>

     * </dl>

     *

     * <p>

     *

     * <dl>

     * <dt><i>HexSignificand:</i>

     * <dd><i>HexNumeral</i>

     * <dd><i>HexNumeral</i> {@code .}

     * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>

     *     </i>{@code .}<i> HexDigits</i>

     * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>

     *     </i>{@code .} <i>HexDigits</i>

     * </dl>

     *

     * <p>

     *

     * <dl>

     * <dt><i>BinaryExponent:</i>

     * <dd><i>BinaryExponentIndicator SignedInteger</i>

     * </dl>

     *

     * <p>

     *

     * <dl>

     * <dt><i>BinaryExponentIndicator:</i>

     * <dd>{@code p}

     * <dd>{@code P}

     * </dl>

     *

     * </blockquote>

     *

     * where <i>Sign</i>, <i>FloatingPointLiteral</i>,

     * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and

     * <i>FloatTypeSuffix</i> are as defined in the lexical structure

     * sections of the <a

     * href="http://java.sun.com/docs/books/jls/html/">Java Language

     * Specification</a>. If {@code s} does not have the form of

     * a <i>FloatValue</i>, then a {@code NumberFormatException}

     * is thrown. Otherwise, {@code s} is regarded as

     * representing an exact decimal value in the usual

     * "computerized scientific notation" or as an exact

     * hexadecimal value; this exact numerical value is then

     * conceptually converted to an "infinitely precise"

     * binary value that is then rounded to type {@code float}

     * by the usual round-to-nearest rule of IEEE 754 floating-point

     * arithmetic, which includes preserving the sign of a zero

     * value. Finally, a {@code Float} object representing this

     * {@code float} value is returned.

     *

     * <p>To interpret localized string representations of a

     * floating-point value, use subclasses of {@link

     * java.text.NumberFormat}.

     *

     * <p>Note that trailing format specifiers, specifiers that

     * determine the type of a floating-point literal

     * ({@code 1.0f} is a {@code float} value;

     * {@code 1.0d} is a {@code double} value), do

     * <em>not</em> influence the results of this method.  In other

     * words, the numerical value of the input string is converted

     * directly to the target floating-point type.  In general, the

     * two-step sequence of conversions, string to {@code double}

     * followed by {@code double} to {@code float}, is

     * <em>not</em> equivalent to converting a string directly to

     * {@code float}.  For example, if first converted to an

     * intermediate {@code double} and then to

     * {@code float}, the string<br>

     * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>

     * results in the {@code float} value

     * {@code 1.0000002f}; if the string is converted directly to

     * {@code float}, <code>1.000000<b>1</b>f</code> results.

     *

     * <p>To avoid calling this method on an invalid string and having

     * a {@code NumberFormatException} be thrown, the documentation

     * for {@link Double#valueOf Double.valueOf} lists a regular

     * expression which can be used to screen the input.

     *

     * @param   s   the string to be parsed.

     * @return  a {@code Float} object holding the value

     *          represented by the {@code String} argument.

     * @throws  NumberFormatException  if the string does not contain a

     *          parsable number.

     */

    public static Float valueOf(String s) throws NumberFormatException {

        return new Float(FloatingDecimal.readJavaFormatString(s).floatValue());

    }

    /**

     * Returns a {@code Float} instance representing the specified

     * {@code float} value.

     * If a new {@code Float} instance is not required, this method

     * should generally be used in preference to the constructor

     * {@link #Float(float)}, as this method is likely to yield

     * significantly better space and time performance by caching

     * frequently requested values.

     *

     * @param  f a float value.

     * @return a {@code Float} instance representing {@code f}.

     * @since  1.5

     */

    public static Float valueOf(float f) {

        return new Float(f);

    }

    /**

     * Returns a new {@code float} initialized to the value

     * represented by the specified {@code String}, as performed

     * by the {@code valueOf} method of class {@code Float}.

     *

     * @param      s   the string to be parsed.

     * @return the {@code float} value represented by the string

     *         argument.

     * @throws  NumberFormatException  if the string does not contain a

     *               parsable {@code float}.

     * @see        java.lang.Float#valueOf(String)

     * @since 1.2

     */

    public static float parseFloat(String s) throws NumberFormatException {

        return FloatingDecimal.readJavaFormatString(s).floatValue();

    }

    /**

     * Returns {@code true} if the specified number is a

     * Not-a-Number (NaN) value, {@code false} otherwise.

     *

     * @param   v   the value to be tested.

     * @return  {@code true} if the argument is NaN;

     *          {@code false} otherwise.

     */

    static public boolean isNaN(float v) {

        return (v != v);

    }

    /**

     * Returns {@code true} if the specified number is infinitely

     * large in magnitude, {@code false} otherwise.

     *

     * @param   v   the value to be tested.

     * @return  {@code true} if the argument is positive infinity or

     *          negative infinity; {@code false} otherwise.

     */

    static public boolean isInfinite(float v) {

        return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);

    }

    /**

     * The value of the Float.

     *

     * @serial

     */

    private final float value;

    /**

     * Constructs a newly allocated {@code Float} object that

     * represents the primitive {@code float} argument.

     *

     * @param   value   the value to be represented by the {@code Float}.

     */

    public Float(float value) {

        this.value = value;

    }

    /**

     * Constructs a newly allocated {@code Float} object that

     * represents the argument converted to type {@code float}.

     *

     * @param   value   the value to be represented by the {@code Float}.

     */

    public Float(double value) {

        this.value = (float)value;

    }

    /**

     * Constructs a newly allocated {@code Float} object that

     * represents the floating-point value of type {@code float}

     * represented by the string. The string is converted to a

     * {@code float} value as if by the {@code valueOf} method.

     *

     * @param      s   a string to be converted to a {@code Float}.

     * @throws  NumberFormatException  if the string does not contain a

     *               parsable number.

     * @see        java.lang.Float#valueOf(java.lang.String)

     */

    public Float(String s) throws NumberFormatException {

        // REMIND: this is inefficient

        this(valueOf(s).floatValue());

    }

    /**

     * Returns {@code true} if this {@code Float} value is a

     * Not-a-Number (NaN), {@code false} otherwise.

     *

     * @return  {@code true} if the value represented by this object is

     *          NaN; {@code false} otherwise.

     */

    public boolean isNaN() {

        return isNaN(value);

    }

    /**

     * Returns {@code true} if this {@code Float} value is

     * infinitely large in magnitude, {@code false} otherwise.

     *

     * @return  {@code true} if the value represented by this object is

     *          positive infinity or negative infinity;

     *          {@code false} otherwise.

     */

    public boolean isInfinite() {

        return isInfinite(value);