/*

 * Copyright (c) 1994, 2009, 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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

 * questions.

 */

package java.lang;

/**

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

 * long} in an object. An object of type {@code Long} contains a

 * single field whose type is {@code long}.

 *

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

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

 * long}, as well as other constants and methods useful when dealing

 * with a {@code long}.

 *

 * <p>Implementation note: The implementations of the "bit twiddling"

 * methods (such as {@link #highestOneBit(long) highestOneBit} and

 * {@link #numberOfTrailingZeros(long) numberOfTrailingZeros}) are

 * based on material from Henry S. Warren, Jr.'s <i>Hacker's

 * Delight</i>, (Addison Wesley, 2002).

 *

 * @author  Lee Boynton

 * @author  Arthur van Hoff

 * @author  Josh Bloch

 * @author  Joseph D. Darcy

 * @since   JDK1.0

 */

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

    /**

     * A constant holding the minimum value a {@code long} can

     * have, -2<sup>63</sup>.

     */

    public static final long MIN_VALUE = 0x8000000000000000L;

    /**

     * A constant holding the maximum value a {@code long} can

     * have, 2<sup>63</sup>-1.

     */

    public static final long MAX_VALUE = 0x7fffffffffffffffL;

    /**

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

     * {@code long}.

     *

     * @since   JDK1.1

     */

    public static final Class<Long>     TYPE = (Class<Long>) Class.getPrimitiveClass("long");

    /**

     * Returns a string representation of the first argument in the

     * radix specified by the second argument.

     *

     * <p>If the radix is smaller than {@code Character.MIN_RADIX}

     * or larger than {@code Character.MAX_RADIX}, then the radix

     * {@code 10} is used instead.

     *

     * <p>If the first argument is negative, the first element of the

     * result is the ASCII minus sign {@code '-'}

     * (<code>'&#92;u002d'</code>). If the first argument is not

     * negative, no sign character appears in the result.

     *

     * <p>The remaining characters of the result represent the magnitude

     * of the first argument. If the magnitude is zero, it is

     * represented by a single zero character {@code '0'}

     * (<code>'&#92;u0030'</code>); otherwise, the first character of

     * the representation of the magnitude will not be the zero

     * character.  The following ASCII characters are used as digits:

     *

     * <blockquote>

     *   {@code 0123456789abcdefghijklmnopqrstuvwxyz}

     * </blockquote>

     *

     * These are <code>'&#92;u0030'</code> through

     * <code>'&#92;u0039'</code> and <code>'&#92;u0061'</code> through

     * <code>'&#92;u007a'</code>. If {@code radix} is

     * <var>N</var>, then the first <var>N</var> of these characters

     * are used as radix-<var>N</var> digits in the order shown. Thus,

     * the digits for hexadecimal (radix 16) are

     * {@code 0123456789abcdef}. If uppercase letters are

     * desired, the {@link java.lang.String#toUpperCase()} method may

     * be called on the result:

     *

     * <blockquote>

     *  {@code Long.toString(n, 16).toUpperCase()}

     * </blockquote>

     *

     * @param   i       a {@code long} to be converted to a string.

     * @param   radix   the radix to use in the string representation.

     * @return  a string representation of the argument in the specified radix.

     * @see     java.lang.Character#MAX_RADIX

     * @see     java.lang.Character#MIN_RADIX

     */

    public static String toString(long i, int radix) {

        if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)

            radix = 10;

        if (radix == 10)

            return toString(i);

        char[] buf = new char[65];

        int charPos = 64;

        boolean negative = (i < 0);

        if (!negative) {

            i = -i;

        }

        while (i <= -radix) {

            buf[charPos--] = Integer.digits[(int)(-(i % radix))];

            i = i / radix;

        }

        buf[charPos] = Integer.digits[(int)(-i)];

        if (negative) {

            buf[--charPos] = '-';

        }

        return new String(buf, charPos, (65 - charPos));

    }

    /**

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

     * argument as an unsigned integer in base 16.

     *

     * <p>The unsigned {@code long} value is the argument plus

     * 2<sup>64</sup> if the argument is negative; otherwise, it is

     * equal to the argument.  This value is converted to a string of

     * ASCII digits in hexadecimal (base 16) with no extra

     * leading {@code 0}s.  If the unsigned magnitude is zero, it

     * is represented by a single zero character {@code '0'}

     * (<code>'&#92;u0030'</code>); otherwise, the first character of

     * the representation of the unsigned magnitude will not be the

     * zero character. The following characters are used as

     * hexadecimal digits:

     *

     * <blockquote>

     *  {@code 0123456789abcdef}

     * </blockquote>

     *

     * These are the characters <code>'&#92;u0030'</code> through

     * <code>'&#92;u0039'</code> and  <code>'&#92;u0061'</code> through

     * <code>'&#92;u0066'</code>.  If uppercase letters are desired,

     * the {@link java.lang.String#toUpperCase()} method may be called

     * on the result:

     *

     * <blockquote>

     *  {@code Long.toHexString(n).toUpperCase()}

     * </blockquote>

     *

     * @param   i   a {@code long} to be converted to a string.

     * @return  the string representation of the unsigned {@code long}

     *          value represented by the argument in hexadecimal

     *          (base 16).

     * @since   JDK 1.0.2

     */

    public static String toHexString(long i) {

        return toUnsignedString(i, 4);

    }

    /**

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

     * argument as an unsigned integer in base 8.

     *

     * <p>The unsigned {@code long} value is the argument plus

     * 2<sup>64</sup> if the argument is negative; otherwise, it is

     * equal to the argument.  This value is converted to a string of

     * ASCII digits in octal (base 8) with no extra leading

     * {@code 0}s.

     *

     * <p>If the unsigned magnitude is zero, it is represented by a

     * single zero character {@code '0'}

     * (<code>'&#92;u0030'</code>); otherwise, the first character of

     * the representation of the unsigned magnitude will not be the

     * zero character. The following characters are used as octal

     * digits:

     *

     * <blockquote>

     *  {@code 01234567}

     * </blockquote>

     *

     * These are the characters <code>'&#92;u0030'</code> through

     * <code>'&#92;u0037'</code>.

     *

     * @param   i   a {@code long} to be converted to a string.

     * @return  the string representation of the unsigned {@code long}

     *          value represented by the argument in octal (base 8).

     * @since   JDK 1.0.2

     */

    public static String toOctalString(long i) {

        return toUnsignedString(i, 3);

    }

    /**

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

     * argument as an unsigned integer in base 2.

     *

     * <p>The unsigned {@code long} value is the argument plus

     * 2<sup>64</sup> if the argument is negative; otherwise, it is

     * equal to the argument.  This value is converted to a string of

     * ASCII digits in binary (base 2) with no extra leading

     * {@code 0}s.  If the unsigned magnitude is zero, it is

     * represented by a single zero character {@code '0'}

     * (<code>'&#92;u0030'</code>); otherwise, the first character of

     * the representation of the unsigned magnitude will not be the

     * zero character. The characters {@code '0'}

     * (<code>'&#92;u0030'</code>) and {@code '1'}

     * (<code>'&#92;u0031'</code>) are used as binary digits.

     *

     * @param   i   a {@code long} to be converted to a string.

     * @return  the string representation of the unsigned {@code long}

     *          value represented by the argument in binary (base 2).

     * @since   JDK 1.0.2

     */

    public static String toBinaryString(long i) {

        return toUnsignedString(i, 1);

    }

    /**

     * Convert the integer to an unsigned number.

     */

    private static String toUnsignedString(long i, int shift) {

        char[] buf = new char[64];

        int charPos = 64;

        int radix = 1 << shift;

        long mask = radix - 1;

        do {

            buf[--charPos] = Integer.digits[(int)(i & mask)];

            i >>>= shift;

        } while (i != 0);

        return new String(buf, charPos, (64 - charPos));

    }

    /**

     * Returns a {@code String} object representing the specified

     * {@code long}.  The argument is converted to signed decimal

     * representation and returned as a string, exactly as if the

     * argument and the radix 10 were given as arguments to the {@link

     * #toString(long, int)} method.

     *

     * @param   i   a {@code long} to be converted.

     * @return  a string representation of the argument in base 10.

     */

    public static String toString(long i) {

        if (i == Long.MIN_VALUE)

            return "-9223372036854775808";

        int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);

        char[] buf = new char[size];

        getChars(i, size, buf);

        return new String(0, size, buf);

    }

    /**

     * Places characters representing the integer i into the

     * character array buf. The characters are placed into

     * the buffer backwards starting with the least significant

     * digit at the specified index (exclusive), and working

     * backwards from there.

     *

     * Will fail if i == Long.MIN_VALUE

     */

    static void getChars(long i, int index, char[] buf) {

        long q;

        int r;

        int charPos = index;

        char sign = 0;

        if (i < 0) {

            sign = '-';

            i = -i;

        }

        // Get 2 digits/iteration using longs until quotient fits into an int

        while (i > Integer.MAX_VALUE) {

            q = i / 100;

            // really: r = i - (q * 100);

            r = (int)(i - ((q << 6) + (q << 5) + (q << 2)));

            i = q;

            buf[--charPos] = Integer.DigitOnes[r];

            buf[--charPos] = Integer.DigitTens[r];

        }

        // Get 2 digits/iteration using ints

        int q2;

        int i2 = (int)i;

        while (i2 >= 65536) {

            q2 = i2 / 100;

            // really: r = i2 - (q * 100);

            r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));

            i2 = q2;

            buf[--charPos] = Integer.DigitOnes[r];

            buf[--charPos] = Integer.DigitTens[r];

        }

        // Fall thru to fast mode for smaller numbers

        // assert(i2 <= 65536, i2);

        for (;;) {

            q2 = (i2 * 52429) >>> (16+3);

            r = i2 - ((q2 << 3) + (q2 << 1));  // r = i2-(q2*10) ...

            buf[--charPos] = Integer.digits[r];

            i2 = q2;

            if (i2 == 0) break;

        }

        if (sign != 0) {

            buf[--charPos] = sign;

        }

    }

    // Requires positive x

    static int stringSize(long x) {

        long p = 10;

        for (int i=1; i<19; i++) {

            if (x < p)

                return i;

            p = 10*p;

        }

        return 19;

    }

    /**

     * Parses the string argument as a signed {@code long} in the

     * radix specified by the second argument. The characters in the

     * string must all be digits of the specified radix (as determined

     * by whether {@link java.lang.Character#digit(char, int)} returns

     * a nonnegative value), except that the first character may be an

     * ASCII minus sign {@code '-'} (<code>'&#92;u002D'</code>) to

     * indicate a negative value or an ASCII plus sign {@code '+'}

     * (<code>'&#92;u002B'</code>) to indicate a positive value. The

     * resulting {@code long} value is returned.

     *

     * <p>Note that neither the character {@code L}

     * (<code>'&#92;u004C'</code>) nor {@code l}

     * (<code>'&#92;u006C'</code>) is permitted to appear at the end

     * of the string as a type indicator, as would be permitted in

     * Java programming language source code - except that either

     * {@code L} or {@code l} may appear as a digit for a

     * radix greater than 22.

     *

     * <p>An exception of type {@code NumberFormatException} is

     * thrown if any of the following situations occurs:

     * <ul>

     *

     * <li>The first argument is {@code null} or is a string of

     * length zero.

     *

     * <li>The {@code radix} is either smaller than {@link

     * java.lang.Character#MIN_RADIX} or larger than {@link

     * java.lang.Character#MAX_RADIX}.

     *

     * <li>Any character of the string is not a digit of the specified

     * radix, except that the first character may be a minus sign

     * {@code '-'} (<code>'&#92;u002d'</code>) or plus sign {@code

     * '+'} (<code>'&#92;u002B'</code>) provided that the string is

     * longer than length 1.

     *

     * <li>The value represented by the string is not a value of type

     *      {@code long}.

     * </ul>

     *

     * <p>Examples:

     * <blockquote><pre>

     * parseLong("0", 10) returns 0L

     * parseLong("473", 10) returns 473L

     * parseLong("+42", 10) returns 42L

     * parseLong("-0", 10) returns 0L

     * parseLong("-FF", 16) returns -255L

     * parseLong("1100110", 2) returns 102L

     * parseLong("99", 8) throws a NumberFormatException

     * parseLong("Hazelnut", 10) throws a NumberFormatException

     * parseLong("Hazelnut", 36) returns 1356099454469L

     * </pre></blockquote>

     *

     * @param      s       the {@code String} containing the

     *                     {@code long} representation to be parsed.

     * @param      radix   the radix to be used while parsing {@code s}.

     * @return     the {@code long} represented by the string argument in

     *             the specified radix.

     * @throws     NumberFormatException  if the string does not contain a

     *             parsable {@code long}.

     */

    public static long parseLong(String s, int radix)

              throws NumberFormatException

    {

        if (s == null) {

            throw new NumberFormatException("null");

        }

        if (radix < Character.MIN_RADIX) {

            throw new NumberFormatException("radix " + radix +

                                            " less than Character.MIN_RADIX");

        }

        if (radix > Character.MAX_RADIX) {

            throw new NumberFormatException("radix " + radix +

                                            " greater than Character.MAX_RADIX");

        }

        long result = 0;

        boolean negative = false;

        int i = 0, len = s.length();

        long limit = -Long.MAX_VALUE;

        long multmin;

        int digit;

        if (len > 0) {

            char firstChar = s.charAt(0);

            if (firstChar < '0') { // Possible leading "+" or "-"

                if (firstChar == '-') {

                    negative = true;

                    limit = Long.MIN_VALUE;

                } else if (firstChar != '+')

                    throw NumberFormatException.forInputString(s);

                if (len == 1) // Cannot have lone "+" or "-"

                    throw NumberFormatException.forInputString(s);

                i++;

            }

            multmin = limit / radix;

            while (i < len) {

                // Accumulating negatively avoids surprises near MAX_VALUE

                digit = Character.digit(s.charAt(i++),radix);

                if (digit < 0) {

                    throw NumberFormatException.forInputString(s);

                }

                if (result < multmin) {

                    throw NumberFormatException.forInputString(s);

                }

                result *= radix;

                if (result < limit + digit) {

                    throw NumberFormatException.forInputString(s);

                }

                result -= digit;

            }

        } else {

            throw NumberFormatException.forInputString(s);

        }

        return negative ? result : -result;

    }

    /**

     * Parses the string argument as a signed decimal {@code long}.

     * The characters in the string must all be decimal digits, except

     * that the first character may be an ASCII minus sign {@code '-'}

     * (<code>&#92;u002D'</code>) to indicate a negative value or an

     * ASCII plus sign {@code '+'} (<code>'&#92;u002B'</code>) to

     * indicate a positive value. The resulting {@code long} value is

     * returned, exactly as if the argument and the radix {@code 10}

     * were given as arguments to the {@link

     * #parseLong(java.lang.String, int)} method.

     *

     * <p>Note that neither the character {@code L}

     * (<code>'&#92;u004C'</code>) nor {@code l}

     * (<code>'&#92;u006C'</code>) is permitted to appear at the end

     * of the string as a type indicator, as would be permitted in

     * Java programming language source code.

     *

     * @param      s   a {@code String} containing the {@code long}

     *             representation to be parsed

     * @return     the {@code long} represented by the argument in

     *             decimal.

     * @throws     NumberFormatException  if the string does not contain a

     *             parsable {@code long}.

     */

    public static long parseLong(String s) throws NumberFormatException {

        return parseLong(s, 10);

    }

    /**

     * Returns a {@code Long} object holding the value

     * extracted from the specified {@code String} when parsed

     * with the radix given by the second argument.  The first

     * argument is interpreted as representing a signed

     * {@code long} in the radix specified by the second

     * argument, exactly as if the arguments were given to the {@link

     * #parseLong(java.lang.String, int)} method. The result is a

     * {@code Long} object that represents the {@code long}

     * value specified by the string.

     *

     * <p>In other words, this method returns a {@code Long} object equal

     * to the value of:

     *

     * <blockquote>

     *  {@code new Long(Long.parseLong(s, radix))}

     * </blockquote>

     *

     * @param      s       the string to be parsed

     * @param      radix   the radix to be used in interpreting {@code s}

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

     *             represented by the string argument in the specified

     *             radix.

     * @throws     NumberFormatException  If the {@code String} does not

     *             contain a parsable {@code long}.

     */

    public static Long valueOf(String s, int radix) throws NumberFormatException {

        return Long.valueOf(parseLong(s, radix));

    }

    /**

     * Returns a {@code Long} object holding the value

     * of the specified {@code String}. The argument is

     * interpreted as representing a signed decimal {@code long},

     * exactly as if the argument were given to the {@link

     * #parseLong(java.lang.String)} method. The result is a

     * {@code Long} object that represents the integer value

     * specified by the string.

     *

     * <p>In other words, this method returns a {@code Long} object

     * equal to the value of:

     *