/*

  * Copyright (c) 2002, 2010, 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;

 import org.apidesign.bck2brwsr.core.JavaScriptBody;

 /**

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

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

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

  * {@code char}.

  * <p>

  * In addition, this class provides several methods for determining

  * a character's category (lowercase letter, digit, etc.) and for converting

  * characters from uppercase to lowercase and vice versa.

  * <p>

  * Character information is based on the Unicode Standard, version 6.0.0.

  * <p>

  * The methods and data of class {@code Character} are defined by

  * the information in the <i>UnicodeData</i> file that is part of the

  * Unicode Character Database maintained by the Unicode

  * Consortium. This file specifies various properties including name

  * and general category for every defined Unicode code point or

  * character range.

  * <p>

  * The file and its description are available from the Unicode Consortium at:

  * <ul>

  * <li><a href="http://www.unicode.org">http://www.unicode.org</a>

  * </ul>

  *

  * <h4><a name="unicode">Unicode Character Representations</a></h4>

  *

  * <p>The {@code char} data type (and therefore the value that a

  * {@code Character} object encapsulates) are based on the

  * original Unicode specification, which defined characters as

  * fixed-width 16-bit entities. The Unicode Standard has since been

  * changed to allow for characters whose representation requires more

  * than 16 bits.  The range of legal <em>code point</em>s is now

  * U+0000 to U+10FFFF, known as <em>Unicode scalar value</em>.

  * (Refer to the <a

  * href="http://www.unicode.org/reports/tr27/#notation"><i>

  * definition</i></a> of the U+<i>n</i> notation in the Unicode

  * Standard.)

  *

  * <p><a name="BMP">The set of characters from U+0000 to U+FFFF is

  * sometimes referred to as the <em>Basic Multilingual Plane (BMP)</em>.

  * <a name="supplementary">Characters</a> whose code points are greater

  * than U+FFFF are called <em>supplementary character</em>s.  The Java

  * platform uses the UTF-16 representation in {@code char} arrays and

  * in the {@code String} and {@code StringBuffer} classes. In

  * this representation, supplementary characters are represented as a pair

  * of {@code char} values, the first from the <em>high-surrogates</em>

  * range, (\uD800-\uDBFF), the second from the

  * <em>low-surrogates</em> range (&#92;uDC00-&#92;uDFFF).

  *

  * <p>A {@code char} value, therefore, represents Basic

  * Multilingual Plane (BMP) code points, including the surrogate

  * code points, or code units of the UTF-16 encoding. An

  * {@code int} value represents all Unicode code points,

  * including supplementary code points. The lower (least significant)

  * 21 bits of {@code int} are used to represent Unicode code

  * points and the upper (most significant) 11 bits must be zero.

  * Unless otherwise specified, the behavior with respect to

  * supplementary characters and surrogate {@code char} values is

  * as follows:

  *

  * <ul>

  * <li>The methods that only accept a {@code char} value cannot support

  * supplementary characters. They treat {@code char} values from the

  * surrogate ranges as undefined characters. For example,

  * {@code Character.isLetter('\u005CuD840')} returns {@code false}, even though

  * this specific value if followed by any low-surrogate value in a string

  * would represent a letter.

  *

  * <li>The methods that accept an {@code int} value support all

  * Unicode characters, including supplementary characters. For

  * example, {@code Character.isLetter(0x2F81A)} returns

  * {@code true} because the code point value represents a letter

  * (a CJK ideograph).

  * </ul>

  *

  * <p>In the Java SE API documentation, <em>Unicode code point</em> is

  * used for character values in the range between U+0000 and U+10FFFF,

  * and <em>Unicode code unit</em> is used for 16-bit

  * {@code char} values that are code units of the <em>UTF-16</em>

  * encoding. For more information on Unicode terminology, refer to the

  * <a href="http://www.unicode.org/glossary/">Unicode Glossary</a>.

  *

  * @author  Lee Boynton

  * @author  Guy Steele

  * @author  Akira Tanaka

  * @author  Martin Buchholz

  * @author  Ulf Zibis

  * @since   1.0

  */

 public final

 class Character implements java.io.Serializable, Comparable<Character> {

     /**

      * The minimum radix available for conversion to and from strings.

      * The constant value of this field is the smallest value permitted

      * for the radix argument in radix-conversion methods such as the

      * {@code digit} method, the {@code forDigit} method, and the

      * {@code toString} method of class {@code Integer}.

      *

      * @see     Character#digit(char, int)

      * @see     Character#forDigit(int, int)

      * @see     Integer#toString(int, int)

      * @see     Integer#valueOf(String)

      */

     public static final int MIN_RADIX = 2;

     /**

      * The maximum radix available for conversion to and from strings.

      * The constant value of this field is the largest value permitted

      * for the radix argument in radix-conversion methods such as the

      * {@code digit} method, the {@code forDigit} method, and the

      * {@code toString} method of class {@code Integer}.

      *

      * @see     Character#digit(char, int)

      * @see     Character#forDigit(int, int)

      * @see     Integer#toString(int, int)

      * @see     Integer#valueOf(String)

      */

     public static final int MAX_RADIX = 36;

     /**

      * The constant value of this field is the smallest value of type

      * {@code char}, {@code '\u005Cu0000'}.

      *

      * @since   1.0.2

      */

     public static final char MIN_VALUE = '\u0000';

     /**

      * The constant value of this field is the largest value of type

      * {@code char}, {@code '\u005CuFFFF'}.

      *

      * @since   1.0.2

      */

     public static final char MAX_VALUE = '\uFFFF';

     /**

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

      * {@code char}.

      *

      * @since   1.1

      */

     public static final Class<Character> TYPE = Class.getPrimitiveClass("char");

     /*

      * Normative general types

      */

     /*

      * General character types

      */

     /**

      * General category "Cn" in the Unicode specification.

      * @since   1.1

      */

     public static final byte UNASSIGNED = 0;

     /**

      * General category "Lu" in the Unicode specification.

      * @since   1.1

      */

     public static final byte UPPERCASE_LETTER = 1;

     /**

      * General category "Ll" in the Unicode specification.

      * @since   1.1

      */

     public static final byte LOWERCASE_LETTER = 2;

     /**

      * General category "Lt" in the Unicode specification.

      * @since   1.1

      */

     public static final byte TITLECASE_LETTER = 3;

     /**

      * General category "Lm" in the Unicode specification.

      * @since   1.1

      */

     public static final byte MODIFIER_LETTER = 4;

     /**

      * General category "Lo" in the Unicode specification.

      * @since   1.1

      */

     public static final byte OTHER_LETTER = 5;

     /**

      * General category "Mn" in the Unicode specification.

      * @since   1.1

      */

     public static final byte NON_SPACING_MARK = 6;

     /**

      * General category "Me" in the Unicode specification.

      * @since   1.1

      */

     public static final byte ENCLOSING_MARK = 7;

     /**

      * General category "Mc" in the Unicode specification.

      * @since   1.1

      */

     public static final byte COMBINING_SPACING_MARK = 8;

     /**

      * General category "Nd" in the Unicode specification.

      * @since   1.1

      */

     public static final byte DECIMAL_DIGIT_NUMBER        = 9;

     /**

      * General category "Nl" in the Unicode specification.

      * @since   1.1

      */

     public static final byte LETTER_NUMBER = 10;

     /**

      * General category "No" in the Unicode specification.

      * @since   1.1

      */

     public static final byte OTHER_NUMBER = 11;

     /**

      * General category "Zs" in the Unicode specification.

      * @since   1.1

      */

     public static final byte SPACE_SEPARATOR = 12;

     /**

      * General category "Zl" in the Unicode specification.

      * @since   1.1

      */

     public static final byte LINE_SEPARATOR = 13;

     /**

      * General category "Zp" in the Unicode specification.

      * @since   1.1

      */

     public static final byte PARAGRAPH_SEPARATOR = 14;

     /**

      * General category "Cc" in the Unicode specification.

      * @since   1.1

      */

     public static final byte CONTROL = 15;

     /**

      * General category "Cf" in the Unicode specification.

      * @since   1.1

      */

     public static final byte FORMAT = 16;

     /**

      * General category "Co" in the Unicode specification.

      * @since   1.1

      */

     public static final byte PRIVATE_USE = 18;

     /**

      * General category "Cs" in the Unicode specification.

      * @since   1.1

      */

     public static final byte SURROGATE = 19;

     /**

      * General category "Pd" in the Unicode specification.

      * @since   1.1

      */

     public static final byte DASH_PUNCTUATION = 20;

     /**

      * General category "Ps" in the Unicode specification.

      * @since   1.1

      */

     public static final byte START_PUNCTUATION = 21;

     /**

      * General category "Pe" in the Unicode specification.

      * @since   1.1

      */

     public static final byte END_PUNCTUATION = 22;

     /**

      * General category "Pc" in the Unicode specification.

      * @since   1.1

      */

     public static final byte CONNECTOR_PUNCTUATION = 23;

     /**

      * General category "Po" in the Unicode specification.

      * @since   1.1

      */

     public static final byte OTHER_PUNCTUATION = 24;

     /**

      * General category "Sm" in the Unicode specification.

      * @since   1.1

      */

     public static final byte MATH_SYMBOL = 25;

     /**

      * General category "Sc" in the Unicode specification.

      * @since   1.1

      */

     public static final byte CURRENCY_SYMBOL = 26;

     /**

      * General category "Sk" in the Unicode specification.

      * @since   1.1

      */

     public static final byte MODIFIER_SYMBOL = 27;

     /**

      * General category "So" in the Unicode specification.

      * @since   1.1

      */

     public static final byte OTHER_SYMBOL = 28;

     /**

      * General category "Pi" in the Unicode specification.

      * @since   1.4

      */

     public static final byte INITIAL_QUOTE_PUNCTUATION = 29;

     /**

      * General category "Pf" in the Unicode specification.

      * @since   1.4

      */

     public static final byte FINAL_QUOTE_PUNCTUATION = 30;

     /**

      * Error flag. Use int (code point) to avoid confusion with U+FFFF.

      */

     static final int ERROR = 0xFFFFFFFF;

     /**

      * Undefined bidirectional character type. Undefined {@code char}

      * values have undefined directionality in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_UNDEFINED = -1;

     /**

      * Strong bidirectional character type "L" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_LEFT_TO_RIGHT = 0;

     /**

      * Strong bidirectional character type "R" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_RIGHT_TO_LEFT = 1;

     /**

     * Strong bidirectional character type "AL" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC = 2;

     /**

      * Weak bidirectional character type "EN" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_EUROPEAN_NUMBER = 3;

     /**

      * Weak bidirectional character type "ES" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_EUROPEAN_NUMBER_SEPARATOR = 4;

     /**

      * Weak bidirectional character type "ET" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_EUROPEAN_NUMBER_TERMINATOR = 5;

     /**

      * Weak bidirectional character type "AN" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_ARABIC_NUMBER = 6;

     /**

      * Weak bidirectional character type "CS" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_COMMON_NUMBER_SEPARATOR = 7;

     /**

      * Weak bidirectional character type "NSM" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_NONSPACING_MARK = 8;

     /**

      * Weak bidirectional character type "BN" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_BOUNDARY_NEUTRAL = 9;

     /**

      * Neutral bidirectional character type "B" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_PARAGRAPH_SEPARATOR = 10;

     /**

      * Neutral bidirectional character type "S" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_SEGMENT_SEPARATOR = 11;

     /**

      * Neutral bidirectional character type "WS" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_WHITESPACE = 12;

     /**

      * Neutral bidirectional character type "ON" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_OTHER_NEUTRALS = 13;

     /**

      * Strong bidirectional character type "LRE" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_LEFT_TO_RIGHT_EMBEDDING = 14;

     /**

      * Strong bidirectional character type "LRO" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_LEFT_TO_RIGHT_OVERRIDE = 15;

     /**

      * Strong bidirectional character type "RLE" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_RIGHT_TO_LEFT_EMBEDDING = 16;

     /**

      * Strong bidirectional character type "RLO" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_RIGHT_TO_LEFT_OVERRIDE = 17;

     /**

      * Weak bidirectional character type "PDF" in the Unicode specification.

      * @since 1.4

      */

     public static final byte DIRECTIONALITY_POP_DIRECTIONAL_FORMAT = 18;

     /**

      * The minimum value of a

      * <a href="http://www.unicode.org/glossary/#high_surrogate_code_unit">

      * Unicode high-surrogate code unit</a>

      * in the UTF-16 encoding, constant {@code '\u005CuD800'}.

      * A high-surrogate is also known as a <i>leading-surrogate</i>.

      *

      * @since 1.5

      */

     public static final char MIN_HIGH_SURROGATE = '\uD800';

     /**

      * The maximum value of a

      * <a href="http://www.unicode.org/glossary/#high_surrogate_code_unit">

      * Unicode high-surrogate code unit</a>

      * in the UTF-16 encoding, constant {@code '\u005CuDBFF'}.

      * A high-surrogate is also known as a <i>leading-surrogate</i>.

      *

      * @since 1.5

      */

     public static final char MAX_HIGH_SURROGATE = '\uDBFF';

     /**

      * The minimum value of a

      * <a href="http://www.unicode.org/glossary/#low_surrogate_code_unit">

      * Unicode low-surrogate code unit</a>

      * in the UTF-16 encoding, constant {@code '\u005CuDC00'}.

      * A low-surrogate is also known as a <i>trailing-surrogate</i>.

      *

      * @since 1.5

      */

     public static final char MIN_LOW_SURROGATE  = '\uDC00';

     /**

      * The maximum value of a

      * <a href="http://www.unicode.org/glossary/#low_surrogate_code_unit">

      * Unicode low-surrogate code unit</a>

      * in the UTF-16 encoding, constant {@code '\u005CuDFFF'}.

      * A low-surrogate is also known as a <i>trailing-surrogate</i>.

      *

      * @since 1.5

      */

     public static final char MAX_LOW_SURROGATE  = '\uDFFF';

     /**

      * The minimum value of a Unicode surrogate code unit in the

      * UTF-16 encoding, constant {@code '\u005CuD800'}.

      *

      * @since 1.5

      */

     public static final char MIN_SURROGATE = MIN_HIGH_SURROGATE;

     /**

      * The maximum value of a Unicode surrogate code unit in the

      * UTF-16 encoding, constant {@code '\u005CuDFFF'}.

      *

      * @since 1.5

      */

     public static final char MAX_SURROGATE = MAX_LOW_SURROGATE;

     /**

      * The minimum value of a

      * <a href="http://www.unicode.org/glossary/#supplementary_code_point">

      * Unicode supplementary code point</a>, constant {@code U+10000}.

      *

      * @since 1.5

      */

     public static final int MIN_SUPPLEMENTARY_CODE_POINT = 0x010000;

     /**

      * The minimum value of a

      * <a href="http://www.unicode.org/glossary/#code_point">

      * Unicode code point</a>, constant {@code U+0000}.

      *

      * @since 1.5

      */

     public static final int MIN_CODE_POINT = 0x000000;

     /**

      * The maximum value of a

      * <a href="http://www.unicode.org/glossary/#code_point">

      * Unicode code point</a>, constant {@code U+10FFFF}.

      *

      * @since 1.5

      */

     public static final int MAX_CODE_POINT = 0X10FFFF;

     /**

      * Instances of this class represent particular subsets of the Unicode

      * character set.  The only family of subsets defined in the

      * {@code Character} class is {@link Character.UnicodeBlock}.

      * Other portions of the Java API may define other subsets for their

      * own purposes.

      *

      * @since 1.2

      */

     public static class Subset  {

         private String name;

         /**

          * Constructs a new {@code Subset} instance.

          *

          * @param  name  The name of this subset

          * @exception NullPointerException if name is {@code null}

          */

         protected Subset(String name) {

             if (name == null) {

                 throw new NullPointerException("name");

             }

             this.name = name;

         }

         /**

          * Compares two {@code Subset} objects for equality.

          * This method returns {@code true} if and only if

          * {@code this} and the argument refer to the same

          * object; since this method is {@code final}, this

          * guarantee holds for all subclasses.

          */

         public final boolean equals(Object obj) {

             return (this == obj);

         }

         /**

          * Returns the standard hash code as defined by the

          * {@link Object#hashCode} method.  This method

          * is {@code final} in order to ensure that the

          * {@code equals} and {@code hashCode} methods will

          * be consistent in all subclasses.

          */

         public final int hashCode() {

             return super.hashCode();

         }

         /**

          * Returns the name of this subset.

          */

         public final String toString() {

             return name;

         }

     }

     // See http://www.unicode.org/Public/UNIDATA/Blocks.txt

     // for the latest specification of Unicode Blocks.

     /**

      * The value of the {@code Character}.

      *

      * @serial

      */

     private final char value;

     /** use serialVersionUID from JDK 1.0.2 for interoperability */

     private static final long serialVersionUID = 3786198910865385080L;

     /**

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

      * represents the specified {@code char} value.

      *

      * @param  value   the value to be represented by the

      *                  {@code Character} object.

      */

     public Character(char value) {

         this.value = value;

     }

     private static class CharacterCache {

         private CharacterCache(){}

         static final Character cache[] = new Character[127 + 1];

         static {

             for (int i = 0; i < cache.length; i++)

                 cache[i] = new Character((char)i);

         }

     }

     /**

      * Returns a <tt>Character</tt> instance representing the specified

      * <tt>char</tt> value.

      * If a new <tt>Character</tt> instance is not required, this method

      * should generally be used in preference to the constructor

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

      * significantly better space and time performance by caching

      * frequently requested values.

      *

      * This method will always cache values in the range {@code

      * '\u005Cu0000'} to {@code '\u005Cu007F'}, inclusive, and may

      * cache other values outside of this range.

      *

      * @param  c a char value.

      * @return a <tt>Character</tt> instance representing <tt>c</tt>.

      * @since  1.5

      */

     public static Character valueOf(char c) {

         if (c <= 127) { // must cache

             return CharacterCache.cache[(int)c];

         }

         return new Character(c);

     }

     /**

      * Returns the value of this {@code Character} object.

      * @return  the primitive {@code char} value represented by

      *          this object.

      */

     public char charValue() {

         return value;

     }

     /**

      * Returns a hash code for this {@code Character}; equal to the result

      * of invoking {@code charValue()}.

      *

      * @return a hash code value for this {@code Character}

      */

     public int hashCode() {

         return (int)value;

     }

     /**

      * Compares this object against the specified object.

      * The result is {@code true} if and only if the argument is not

      * {@code null} and is a {@code Character} object that

      * represents the same {@code char} value as this object.

      *

      * @param   obj   the object to compare with.

      * @return  {@code true} if the objects are the same;

      *          {@code false} otherwise.

      */

     public boolean equals(Object obj) {

         if (obj instanceof Character) {

             return value == ((Character)obj).charValue();

         }

         return false;

     }

     /**

      * Returns a {@code String} object representing this

      * {@code Character}'s value.  The result is a string of

      * length 1 whose sole component is the primitive

      * {@code char} value represented by this

      * {@code Character} object.

      *

      * @return  a string representation of this object.

      */

     public String toString() {

         char buf[] = {value};

         return String.valueOf(buf);

     }

     /**

      * Returns a {@code String} object representing the

      * specified {@code char}.  The result is a string of length

      * 1 consisting solely of the specified {@code char}.

      *

      * @param c the {@code char} to be converted

      * @return the string representation of the specified {@code char}

      * @since 1.4

      */

     public static String toString(char c) {

         return String.valueOf(c);

     }

     /**

      * Determines whether the specified code point is a valid

      * <a href="http://www.unicode.org/glossary/#code_point">

      * Unicode code point value</a>.

      *

      * @param  codePoint the Unicode code point to be tested

      * @return {@code true} if the specified code point value is between

      *         {@link #MIN_CODE_POINT} and

      *         {@link #MAX_CODE_POINT} inclusive;

      *         {@code false} otherwise.

      * @since  1.5

      */

     public static boolean isValidCodePoint(int codePoint) {

         // Optimized form of:

         //     codePoint >= MIN_CODE_POINT && codePoint <= MAX_CODE_POINT

         int plane = codePoint >>> 16;

         return plane < ((MAX_CODE_POINT + 1) >>> 16);

     }

     /**

      * Determines whether the specified character (Unicode code point)

      * is in the <a href="#BMP">Basic Multilingual Plane (BMP)</a>.

      * Such code points can be represented using a single {@code char}.

      *

      * @param  codePoint the character (Unicode code point) to be tested

      * @return {@code true} if the specified code point is between

      *         {@link #MIN_VALUE} and {@link #MAX_VALUE} inclusive;

      *         {@code false} otherwise.

      * @since  1.7

      */

     public static boolean isBmpCodePoint(int codePoint) {

         return codePoint >>> 16 == 0;

         // Optimized form of:

         //     codePoint >= MIN_VALUE && codePoint <= MAX_VALUE

         // We consistently use logical shift (>>>) to facilitate

         // additional runtime optimizations.

     }

     /**

      * Determines whether the specified character (Unicode code point)

      * is in the <a href="#supplementary">supplementary character</a> range.

      *

      * @param  codePoint the character (Unicode code point) to be tested

      * @return {@code true} if the specified code point is between

      *         {@link #MIN_SUPPLEMENTARY_CODE_POINT} and

      *         {@link #MAX_CODE_POINT} inclusive;

      *         {@code false} otherwise.

      * @since  1.5

      */

     public static boolean isSupplementaryCodePoint(int codePoint) {

         return codePoint >= MIN_SUPPLEMENTARY_CODE_POINT

             && codePoint <  MAX_CODE_POINT + 1;

     }

     /**

      * Determines if the given {@code char} value is a

      * <a href="http://www.unicode.org/glossary/#high_surrogate_code_unit">

      * Unicode high-surrogate code unit</a>

      * (also known as <i>leading-surrogate code unit</i>).

      *

      * <p>Such values do not represent characters by themselves,

      * but are used in the representation of

      * <a href="#supplementary">supplementary characters</a>

      * in the UTF-16 encoding.

      *

      * @param  ch the {@code char} value to be tested.

      * @return {@code true} if the {@code char} value is between

      *         {@link #MIN_HIGH_SURROGATE} and

      *         {@link #MAX_HIGH_SURROGATE} inclusive;

      *         {@code false} otherwise.

      * @see    Character#isLowSurrogate(char)

      * @see    Character.UnicodeBlock#of(int)

      * @since  1.5

      */

     public static boolean isHighSurrogate(char ch) {

         // Help VM constant-fold; MAX_HIGH_SURROGATE + 1 == MIN_LOW_SURROGATE

         return ch >= MIN_HIGH_SURROGATE && ch < (MAX_HIGH_SURROGATE + 1);

     }

     /**

      * Determines if the given {@code char} value is a

      * <a href="http://www.unicode.org/glossary/#low_surrogate_code_unit">

      * Unicode low-surrogate code unit</a>

      * (also known as <i>trailing-surrogate code unit</i>).

      *

      * <p>Such values do not represent characters by themselves,

      * but are used in the representation of

      * <a href="#supplementary">supplementary characters</a>

      * in the UTF-16 encoding.

      *

      * @param  ch the {@code char} value to be tested.

      * @return {@code true} if the {@code char} value is between

      *         {@link #MIN_LOW_SURROGATE} and

      *         {@link #MAX_LOW_SURROGATE} inclusive;

      *         {@code false} otherwise.

      * @see    Character#isHighSurrogate(char)

      * @since  1.5

      */

     public static boolean isLowSurrogate(char ch) {

         return ch >= MIN_LOW_SURROGATE && ch < (MAX_LOW_SURROGATE + 1);

     }

     /**

      * Determines if the given {@code char} value is a Unicode

      * <i>surrogate code unit</i>.

      *

      * <p>Such values do not represent characters by themselves,

      * but are used in the representation of

      * <a href="#supplementary">supplementary characters</a>

      * in the UTF-16 encoding.

      *

      * <p>A char value is a surrogate code unit if and only if it is either

      * a {@linkplain #isLowSurrogate(char) low-surrogate code unit} or

      * a {@linkplain #isHighSurrogate(char) high-surrogate code unit}.

      *

      * @param  ch the {@code char} value to be tested.

      * @return {@code true} if the {@code char} value is between

      *         {@link #MIN_SURROGATE} and

      *         {@link #MAX_SURROGATE} inclusive;

      *         {@code false} otherwise.

      * @since  1.7

      */

     public static boolean isSurrogate(char ch) {

         return ch >= MIN_SURROGATE && ch < (MAX_SURROGATE + 1);

     }

     /**

      * Determines whether the specified pair of {@code char}

      * values is a valid

      * <a href="http://www.unicode.org/glossary/#surrogate_pair">

      * Unicode surrogate pair</a>.

      * <p>This method is equivalent to the expression:

      * <blockquote><pre>

      * isHighSurrogate(high) && isLowSurrogate(low)

      * </pre></blockquote>

      *

      * @param  high the high-surrogate code value to be tested

      * @param  low the low-surrogate code value to be tested

      * @return {@code true} if the specified high and

      * low-surrogate code values represent a valid surrogate pair;

      * {@code false} otherwise.

      * @since  1.5

      */

     public static boolean isSurrogatePair(char high, char low) {

         return isHighSurrogate(high) && isLowSurrogate(low);

     }

     /**

      * Determines the number of {@code char} values needed to

      * represent the specified character (Unicode code point). If the

      * specified character is equal to or greater than 0x10000, then

      * the method returns 2. Otherwise, the method returns 1.

      *

      * <p>This method doesn't validate the specified character to be a

      * valid Unicode code point. The caller must validate the

      * character value using {@link #isValidCodePoint(int) isValidCodePoint}

      * if necessary.

      *

      * @param   codePoint the character (Unicode code point) to be tested.

      * @return  2 if the character is a valid supplementary character; 1 otherwise.

      * @see     Character#isSupplementaryCodePoint(int)

      * @since   1.5

      */

     public static int charCount(int codePoint) {

         return codePoint >= MIN_SUPPLEMENTARY_CODE_POINT ? 2 : 1;

     }

     /**

      * Converts the specified surrogate pair to its supplementary code

      * point value. This method does not validate the specified

      * surrogate pair. The caller must validate it using {@link

      * #isSurrogatePair(char, char) isSurrogatePair} if necessary.

      *

      * @param  high the high-surrogate code unit

      * @param  low the low-surrogate code unit

      * @return the supplementary code point composed from the

      *         specified surrogate pair.

      * @since  1.5

      */

     public static int toCodePoint(char high, char low) {

         // Optimized form of:

         // return ((high - MIN_HIGH_SURROGATE) << 10)

         //         + (low - MIN_LOW_SURROGATE)

         //         + MIN_SUPPLEMENTARY_CODE_POINT;

         return ((high << 10) + low) + (MIN_SUPPLEMENTARY_CODE_POINT

                                        - (MIN_HIGH_SURROGATE << 10)

                                        - MIN_LOW_SURROGATE);

     }

     /**

      * Returns the code point at the given index of the

      * {@code CharSequence}. If the {@code char} value at

      * the given index in the {@code CharSequence} is in the

      * high-surrogate range, the following index is less than the

      * length of the {@code CharSequence}, and the

      * {@code char} value at the following index is in the

      * low-surrogate range, then the supplementary code point

      * corresponding to this surrogate pair is returned. Otherwise,

      * the {@code char} value at the given index is returned.

      *

      * @param seq a sequence of {@code char} values (Unicode code

      * units)

      * @param index the index to the {@code char} values (Unicode

      * code units) in {@code seq} to be converted

      * @return the Unicode code point at the given index

      * @exception NullPointerException if {@code seq} is null.

      * @exception IndexOutOfBoundsException if the value

      * {@code index} is negative or not less than

      * {@link CharSequence#length() seq.length()}.

      * @since  1.5

      */

     public static int codePointAt(CharSequence seq, int index) {

         char c1 = seq.charAt(index++);

         if (isHighSurrogate(c1)) {

             if (index < seq.length()) {

                 char c2 = seq.charAt(index);

                 if (isLowSurrogate(c2)) {

                     return toCodePoint(c1, c2);

                 }

             }

         }

         return c1;

     }

     /**

      * Returns the code point at the given index of the

      * {@code char} array. If the {@code char} value at

      * the given index in the {@code char} array is in the

      * high-surrogate range, the following index is less than the

      * length of the {@code char} array, and the

      * {@code char} value at the following index is in the

      * low-surrogate range, then the supplementary code point

      * corresponding to this surrogate pair is returned. Otherwise,

      * the {@code char} value at the given index is returned.

      *

      * @param a the {@code char} array

      * @param index the index to the {@code char} values (Unicode

      * code units) in the {@code char} array to be converted

      * @return the Unicode code point at the given index

      * @exception NullPointerException if {@code a} is null.

      * @exception IndexOutOfBoundsException if the value

      * {@code index} is negative or not less than

      * the length of the {@code char} array.

      * @since  1.5

      */

     public static int codePointAt(char[] a, int index) {

         return codePointAtImpl(a, index, a.length);

     }

     /**

      * Returns the code point at the given index of the

      * {@code char} array, where only array elements with

      * {@code index} less than {@code limit} can be used. If

      * the {@code char} value at the given index in the

      * {@code char} array is in the high-surrogate range, the

      * following index is less than the {@code limit}, and the

      * {@code char} value at the following index is in the

      * low-surrogate range, then the supplementary code point

      * corresponding to this surrogate pair is returned. Otherwise,

      * the {@code char} value at the given index is returned.

      *

      * @param a the {@code char} array

      * @param index the index to the {@code char} values (Unicode

      * code units) in the {@code char} array to be converted

      * @param limit the index after the last array element that

      * can be used in the {@code char} array

      * @return the Unicode code point at the given index

      * @exception NullPointerException if {@code a} is null.

      * @exception IndexOutOfBoundsException if the {@code index}

      * argument is negative or not less than the {@code limit}

      * argument, or if the {@code limit} argument is negative or

      * greater than the length of the {@code char} array.

      * @since  1.5

      */

     public static int codePointAt(char[] a, int index, int limit) {

         if (index >= limit || limit < 0 || limit > a.length) {

             throw new IndexOutOfBoundsException();

         }

         return codePointAtImpl(a, index, limit);

     }

     // throws ArrayIndexOutofBoundsException if index out of bounds

     static int codePointAtImpl(char[] a, int index, int limit) {

         char c1 = a[index++];

         if (isHighSurrogate(c1)) {

             if (index < limit) {

                 char c2 = a[index];

                 if (isLowSurrogate(c2)) {

                     return toCodePoint(c1, c2);

                 }

             }

         }

         return c1;

     }

     /**

      * Returns the code point preceding the given index of the

      * {@code CharSequence}. If the {@code char} value at

      * {@code (index - 1)} in the {@code CharSequence} is in

      * the low-surrogate range, {@code (index - 2)} is not

      * negative, and the {@code char} value at {@code (index - 2)}

      * in the {@code CharSequence} is in the

      * high-surrogate range, then the supplementary code point

      * corresponding to this surrogate pair is returned. Otherwise,

      * the {@code char} value at {@code (index - 1)} is

      * returned.

      *

      * @param seq the {@code CharSequence} instance

      * @param index the index following the code point that should be returned

      * @return the Unicode code point value before the given index.

      * @exception NullPointerException if {@code seq} is null.

      * @exception IndexOutOfBoundsException if the {@code index}

      * argument is less than 1 or greater than {@link

      * CharSequence#length() seq.length()}.

      * @since  1.5

      */

     public static int codePointBefore(CharSequence seq, int index) {

         char c2 = seq.charAt(--index);

         if (isLowSurrogate(c2)) {

             if (index > 0) {

                 char c1 = seq.charAt(--index);

                 if (isHighSurrogate(c1)) {

                     return toCodePoint(c1, c2);

                 }

             }

         }

         return c2;

     }

     /**

      * Returns the code point preceding the given index of the

      * {@code char} array. If the {@code char} value at

      * {@code (index - 1)} in the {@code char} array is in

      * the low-surrogate range, {@code (index - 2)} is not

      * negative, and the {@code char} value at {@code (index - 2)}

      * in the {@code char} array is in the

      * high-surrogate range, then the supplementary code point

      * corresponding to this surrogate pair is returned. Otherwise,

      * the {@code char} value at {@code (index - 1)} is

      * returned.

      *

      * @param a the {@code char} array

      * @param index the index following the code point that should be returned

      * @return the Unicode code point value before the given index.

      * @exception NullPointerException if {@code a} is null.

      * @exception IndexOutOfBoundsException if the {@code index}

      * argument is less than 1 or greater than the length of the

      * {@code char} array

      * @since  1.5

      */

     public static int codePointBefore(char[] a, int index) {

         return codePointBeforeImpl(a, index, 0);

     }

     /**

      * Returns the code point preceding the given index of the

      * {@code char} array, where only array elements with

      * {@code index} greater than or equal to {@code start}

      * can be used. If the {@code char} value at {@code (index - 1)}

      * in the {@code char} array is in the

      * low-surrogate range, {@code (index - 2)} is not less than

      * {@code start}, and the {@code char} value at

      * {@code (index - 2)} in the {@code char} array is in

      * the high-surrogate range, then the supplementary code point

      * corresponding to this surrogate pair is returned. Otherwise,

      * the {@code char} value at {@code (index - 1)} is

      * returned.

      *

      * @param a the {@code char} array

      * @param index the index following the code point that should be returned

      * @param start the index of the first array element in the

      * {@code char} array

      * @return the Unicode code point value before the given index.

      * @exception NullPointerException if {@code a} is null.

      * @exception IndexOutOfBoundsException if the {@code index}

      * argument is not greater than the {@code start} argument or

      * is greater than the length of the {@code char} array, or

      * if the {@code start} argument is negative or not less than

      * the length of the {@code char} array.

      * @since  1.5

      */

     public static int codePointBefore(char[] a, int index, int start) {

         if (index <= start || start < 0 || start >= a.length) {

             throw new IndexOutOfBoundsException();

         }

         return codePointBeforeImpl(a, index, start);

     }

     // throws ArrayIndexOutofBoundsException if index-1 out of bounds

     static int codePointBeforeImpl(char[] a, int index, int start) {

         char c2 = a[--index];

         if (isLowSurrogate(c2)) {

             if (index > start) {

                 char c1 = a[--index];

                 if (isHighSurrogate(c1)) {

                     return toCodePoint(c1, c2);

                 }

             }

         }

         return c2;

     }

     /**

      * Returns the leading surrogate (a

      * <a href="http://www.unicode.org/glossary/#high_surrogate_code_unit">

      * high surrogate code unit</a>) of the

      * <a href="http://www.unicode.org/glossary/#surrogate_pair">

      * surrogate pair</a>

      * representing the specified supplementary character (Unicode

      * code point) in the UTF-16 encoding.  If the specified character

      * is not a

      * <a href="Character.html#supplementary">supplementary character</a>,

      * an unspecified {@code char} is returned.

      *

      * <p>If

      * {@link #isSupplementaryCodePoint isSupplementaryCodePoint(x)}

      * is {@code true}, then

      * {@link #isHighSurrogate isHighSurrogate}{@code (highSurrogate(x))} and

      * {@link #toCodePoint toCodePoint}{@code (highSurrogate(x), }{@link #lowSurrogate lowSurrogate}{@code (x)) == x}

      * are also always {@code true}.

      *

      * @param   codePoint a supplementary character (Unicode code point)

      * @return  the leading surrogate code unit used to represent the

      *          character in the UTF-16 encoding

      * @since   1.7

      */

     public static char highSurrogate(int codePoint) {

         return (char) ((codePoint >>> 10)

             + (MIN_HIGH_SURROGATE - (MIN_SUPPLEMENTARY_CODE_POINT >>> 10)));

     }

     /**

      * Returns the trailing surrogate (a

      * <a href="http://www.unicode.org/glossary/#low_surrogate_code_unit">

      * low surrogate code unit</a>) of the

      * <a href="http://www.unicode.org/glossary/#surrogate_pair">

      * surrogate pair</a>

      * representing the specified supplementary character (Unicode

      * code point) in the UTF-16 encoding.  If the specified character

      * is not a

      * <a href="Character.html#supplementary">supplementary character</a>,

      * an unspecified {@code char} is returned.

      *

      * <p>If

      * {@link #isSupplementaryCodePoint isSupplementaryCodePoint(x)}

      * is {@code true}, then

      * {@link #isLowSurrogate isLowSurrogate}{@code (lowSurrogate(x))} and

      * {@link #toCodePoint toCodePoint}{@code (}{@link #highSurrogate highSurrogate}{@code (x), lowSurrogate(x)) == x}

      * are also always {@code true}.

      *

      * @param   codePoint a supplementary character (Unicode code point)

      * @return  the trailing surrogate code unit used to represent the

      *          character in the UTF-16 encoding

      * @since   1.7

      */

     public static char lowSurrogate(int codePoint) {

         return (char) ((codePoint & 0x3ff) + MIN_LOW_SURROGATE);

     }

     /**

      * Converts the specified character (Unicode code point) to its

      * UTF-16 representation. If the specified code point is a BMP

      * (Basic Multilingual Plane or Plane 0) value, the same value is

      * stored in {@code dst[dstIndex]}, and 1 is returned. If the

      * specified code point is a supplementary character, its

      * surrogate values are stored in {@code dst[dstIndex]}

      * (high-surrogate) and {@code dst[dstIndex+1]}

      * (low-surrogate), and 2 is returned.

      *

      * @param  codePoint the character (Unicode code point) to be converted.

      * @param  dst an array of {@code char} in which the

      * {@code codePoint}'s UTF-16 value is stored.

      * @param dstIndex the start index into the {@code dst}

      * array where the converted value is stored.

      * @return 1 if the code point is a BMP code point, 2 if the

      * code point is a supplementary code point.

      * @exception IllegalArgumentException if the specified

      * {@code codePoint} is not a valid Unicode code point.

      * @exception NullPointerException if the specified {@code dst} is null.

      * @exception IndexOutOfBoundsException if {@code dstIndex}

      * is negative or not less than {@code dst.length}, or if

      * {@code dst} at {@code dstIndex} doesn't have enough

      * array element(s) to store the resulting {@code char}

      * value(s). (If {@code dstIndex} is equal to

      * {@code dst.length-1} and the specified

      * {@code codePoint} is a supplementary character, the

      * high-surrogate value is not stored in

      * {@code dst[dstIndex]}.)

      * @since  1.5

      */

     public static int toChars(int codePoint, char[] dst, int dstIndex) {

         if (isBmpCodePoint(codePoint)) {

             dst[dstIndex] = (char) codePoint;

             return 1;

         } else if (isValidCodePoint(codePoint)) {

             toSurrogates(codePoint, dst, dstIndex);

             return 2;

         } else {

             throw new IllegalArgumentException();

         }

     }

     /**

      * Converts the specified character (Unicode code point) to its

      * UTF-16 representation stored in a {@code char} array. If

      * the specified code point is a BMP (Basic Multilingual Plane or

      * Plane 0) value, the resulting {@code char} array has

      * the same value as {@code codePoint}. If the specified code

      * point is a supplementary code point, the resulting

      * {@code char} array has the corresponding surrogate pair.

      *

      * @param  codePoint a Unicode code point

      * @return a {@code char} array having

      *         {@code codePoint}'s UTF-16 representation.

      * @exception IllegalArgumentException if the specified

      * {@code codePoint} is not a valid Unicode code point.

      * @since  1.5

      */

     public static char[] toChars(int codePoint) {

         if (isBmpCodePoint(codePoint)) {

             return new char[] { (char) codePoint };

         } else if (isValidCodePoint(codePoint)) {

             char[] result = new char[2];

             toSurrogates(codePoint, result, 0);

             return result;

         } else {

             throw new IllegalArgumentException();

         }

     }

     static void toSurrogates(int codePoint, char[] dst, int index) {

         // We write elements "backwards" to guarantee all-or-nothing

         dst[index+1] = lowSurrogate(codePoint);

         dst[index] = highSurrogate(codePoint);

     }

     /**

      * Returns the number of Unicode code points in the text range of

      * the specified char sequence. The text range begins at the

      * specified {@code beginIndex} and extends to the

      * {@code char} at index {@code endIndex - 1}. Thus the

      * length (in {@code char}s) of the text range is

      * {@code endIndex-beginIndex}. Unpaired surrogates within

      * the text range count as one code point each.

      *

      * @param seq the char sequence

      * @param beginIndex the index to the first {@code char} of

      * the text range.

      * @param endIndex the index after the last {@code char} of

      * the text range.

      * @return the number of Unicode code points in the specified text

      * range

      * @exception NullPointerException if {@code seq} is null.

      * @exception IndexOutOfBoundsException if the

      * {@code beginIndex} is negative, or {@code endIndex}

      * is larger than the length of the given sequence, or

      * {@code beginIndex} is larger than {@code endIndex}.

      * @since  1.5

      */

     public static int codePointCount(CharSequence seq, int beginIndex, int endIndex) {

         int length = seq.length();

         if (beginIndex < 0 || endIndex > length || beginIndex > endIndex) {

             throw new IndexOutOfBoundsException();

         }

         int n = endIndex - beginIndex;

         for (int i = beginIndex; i < endIndex; ) {

             if (isHighSurrogate(seq.charAt(i++)) && i < endIndex &&

                 isLowSurrogate(seq.charAt(i))) {

                 n--;

                 i++;

             }

         }

         return n;

     }

     /**

      * Returns the number of Unicode code points in a subarray of the

      * {@code char} array argument. The {@code offset}

      * argument is the index of the first {@code char} of the

      * subarray and the {@code count} argument specifies the

      * length of the subarray in {@code char}s. Unpaired

      * surrogates within the subarray count as one code point each.

      *

      * @param a the {@code char} array

      * @param offset the index of the first {@code char} in the

      * given {@code char} array

      * @param count the length of the subarray in {@code char}s

      * @return the number of Unicode code points in the specified subarray

      * @exception NullPointerException if {@code a} is null.

      * @exception IndexOutOfBoundsException if {@code offset} or

      * {@code count} is negative, or if {@code offset +

      * count} is larger than the length of the given array.

      * @since  1.5

      */

     public static int codePointCount(char[] a, int offset, int count) {

         if (count > a.length - offset || offset < 0 || count < 0) {

             throw new IndexOutOfBoundsException();

         }

         return codePointCountImpl(a, offset, count);

     }

     static int codePointCountImpl(char[] a, int offset, int count) {

         int endIndex = offset + count;

         int n = count;

         for (int i = offset; i < endIndex; ) {

             if (isHighSurrogate(a[i++]) && i < endIndex &&

                 isLowSurrogate(a[i])) {

                 n--;

                 i++;

             }

         }

         return n;

     }

     /**

      * Returns the index within the given char sequence that is offset

      * from the given {@code index} by {@code codePointOffset}

      * code points. Unpaired surrogates within the text range given by

      * {@code index} and {@code codePointOffset} count as

      * one code point each.

      *

      * @param seq the char sequence

      * @param index the index to be offset

      * @param codePointOffset the offset in code points

      * @return the index within the char sequence

      * @exception NullPointerException if {@code seq} is null.

      * @exception IndexOutOfBoundsException if {@code index}

      *   is negative or larger then the length of the char sequence,

      *   or if {@code codePointOffset} is positive and the

      *   subsequence starting with {@code index} has fewer than

      *   {@code codePointOffset} code points, or if

      *   {@code codePointOffset} is negative and the subsequence

      *   before {@code index} has fewer than the absolute value

      *   of {@code codePointOffset} code points.

      * @since 1.5

      */

     public static int offsetByCodePoints(CharSequence seq, int index,

                                          int codePointOffset) {

         int length = seq.length();

         if (index < 0 || index > length) {

             throw new IndexOutOfBoundsException();

         }

         int x = index;

         if (codePointOffset >= 0) {

             int i;

             for (i = 0; x < length && i < codePointOffset; i++) {

                 if (isHighSurrogate(seq.charAt(x++)) && x < length &&

                     isLowSurrogate(seq.charAt(x))) {

                     x++;

                 }

             }

             if (i < codePointOffset) {

                 throw new IndexOutOfBoundsException();

             }

         } else {

             int i;

             for (i = codePointOffset; x > 0 && i < 0; i++) {

                 if (isLowSurrogate(seq.charAt(--x)) && x > 0 &&

                     isHighSurrogate(seq.charAt(x-1))) {

                     x--;

                 }

             }

             if (i < 0) {

                 throw new IndexOutOfBoundsException();

             }

         }

         return x;

     }

     /**

      * Returns the index within the given {@code char} subarray

      * that is offset from the given {@code index} by

      * {@code codePointOffset} code points. The

      * {@code start} and {@code count} arguments specify a

      * subarray of the {@code char} array. Unpaired surrogates

      * within the text range given by {@code index} and

      * {@code codePointOffset} count as one code point each.

      *

      * @param a the {@code char} array

      * @param start the index of the first {@code char} of the

      * subarray

      * @param count the length of the subarray in {@code char}s

      * @param index the index to be offset

      * @param codePointOffset the offset in code points

      * @return the index within the subarray

      * @exception NullPointerException if {@code a} is null.

      * @exception IndexOutOfBoundsException

      *   if {@code start} or {@code count} is negative,

      *   or if {@code start + count} is larger than the length of

      *   the given array,

      *   or if {@code index} is less than {@code start} or

      *   larger then {@code start + count},

      *   or if {@code codePointOffset} is positive and the text range

      *   starting with {@code index} and ending with {@code start + count - 1}

      *   has fewer than {@code codePointOffset} code

      *   points,

      *   or if {@code codePointOffset} is negative and the text range

      *   starting with {@code start} and ending with {@code index - 1}

      *   has fewer than the absolute value of

      *   {@code codePointOffset} code points.

      * @since 1.5

      */

     public static int offsetByCodePoints(char[] a, int start, int count,

                                          int index, int codePointOffset) {

         if (count > a.length-start || start < 0 || count < 0

             || index < start || index > start+count) {

             throw new IndexOutOfBoundsException();

         }

         return offsetByCodePointsImpl(a, start, count, index, codePointOffset);

     }

     static int offsetByCodePointsImpl(char[]a, int start, int count,

                                       int index, int codePointOffset) {

         int x = index;

         if (codePointOffset >= 0) {

             int limit = start + count;

             int i;

             for (i = 0; x < limit && i < codePointOffset; i++) {

                 if (isHighSurrogate(a[x++]) && x < limit &&

                     isLowSurrogate(a[x])) {

                     x++;

                 }

             }

             if (i < codePointOffset) {

                 throw new IndexOutOfBoundsException();

             }

         } else {

             int i;

             for (i = codePointOffset; x > start && i < 0; i++) {

                 if (isLowSurrogate(a[--x]) && x > start &&

                     isHighSurrogate(a[x-1])) {

                     x--;

                 }

             }

             if (i < 0) {

                 throw new IndexOutOfBoundsException();

             }

         }

         return x;

     }

     /**

      * Determines if the specified character is a lowercase character.

      * <p>

      * A character is lowercase if its general category type, provided

      * by {@code Character.getType(ch)}, is

      * {@code LOWERCASE_LETTER}, or it has contributory property

      * Other_Lowercase as defined by the Unicode Standard.

      * <p>

      * The following are examples of lowercase characters:

      * <p><blockquote><pre>

      * a b c d e f g h i j k l m n o p q r s t u v w x y z

      * '\u00DF' '\u00E0' '\u00E1' '\u00E2' '\u00E3' '\u00E4' '\u00E5' '\u00E6'

      * '\u00E7' '\u00E8' '\u00E9' '\u00EA' '\u00EB' '\u00EC' '\u00ED' '\u00EE'

      * '\u00EF' '\u00F0' '\u00F1' '\u00F2' '\u00F3' '\u00F4' '\u00F5' '\u00F6'

      * '\u00F8' '\u00F9' '\u00FA' '\u00FB' '\u00FC' '\u00FD' '\u00FE' '\u00FF'

      * </pre></blockquote>

      * <p> Many other Unicode characters are lowercase too.

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #isLowerCase(int)} method.

      *

      * @param   ch   the character to be tested.

      * @return  {@code true} if the character is lowercase;

      *          {@code false} otherwise.

      * @see     Character#isLowerCase(char)

      * @see     Character#isTitleCase(char)

      * @see     Character#toLowerCase(char)

      * @see     Character#getType(char)

      */

     public static boolean isLowerCase(char ch) {

         return ch == toLowerCase(ch);

     }

     /**

      * Determines if the specified character is an uppercase character.

      * <p>

      * A character is uppercase if its general category type, provided by

      * {@code Character.getType(ch)}, is {@code UPPERCASE_LETTER}.

      * or it has contributory property Other_Uppercase as defined by the Unicode Standard.

      * <p>

      * The following are examples of uppercase characters:

      * <p><blockquote><pre>

      * A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

      * '\u00C0' '\u00C1' '\u00C2' '\u00C3' '\u00C4' '\u00C5' '\u00C6' '\u00C7'

      * '\u00C8' '\u00C9' '\u00CA' '\u00CB' '\u00CC' '\u00CD' '\u00CE' '\u00CF'

      * '\u00D0' '\u00D1' '\u00D2' '\u00D3' '\u00D4' '\u00D5' '\u00D6' '\u00D8'

      * '\u00D9' '\u00DA' '\u00DB' '\u00DC' '\u00DD' '\u00DE'

      * </pre></blockquote>

      * <p> Many other Unicode characters are uppercase too.<p>

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #isUpperCase(int)} method.

      *

      * @param   ch   the character to be tested.

      * @return  {@code true} if the character is uppercase;

      *          {@code false} otherwise.

      * @see     Character#isLowerCase(char)

      * @see     Character#isTitleCase(char)

      * @see     Character#toUpperCase(char)

      * @see     Character#getType(char)

      * @since   1.0

      */

     public static boolean isUpperCase(char ch) {

         return ch == toUpperCase(ch);

     }

     /**

      * Determines if the specified character is a titlecase character.

      * <p>

      * A character is a titlecase character if its general

      * category type, provided by {@code Character.getType(ch)},

      * is {@code TITLECASE_LETTER}.

      * <p>

      * Some characters look like pairs of Latin letters. For example, there

      * is an uppercase letter that looks like "LJ" and has a corresponding

      * lowercase letter that looks like "lj". A third form, which looks like "Lj",

      * is the appropriate form to use when rendering a word in lowercase

      * with initial capitals, as for a book title.

      * <p>

      * These are some of the Unicode characters for which this method returns

      * {@code true}:

      * <ul>

      * <li>{@code LATIN CAPITAL LETTER D WITH SMALL LETTER Z WITH CARON}

      * <li>{@code LATIN CAPITAL LETTER L WITH SMALL LETTER J}

      * <li>{@code LATIN CAPITAL LETTER N WITH SMALL LETTER J}

      * <li>{@code LATIN CAPITAL LETTER D WITH SMALL LETTER Z}

      * </ul>

      * <p> Many other Unicode characters are titlecase too.<p>

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #isTitleCase(int)} method.

      *

      * @param   ch   the character to be tested.

      * @return  {@code true} if the character is titlecase;

      *          {@code false} otherwise.

      * @see     Character#isLowerCase(char)

      * @see     Character#isUpperCase(char)

      * @see     Character#toTitleCase(char)

      * @see     Character#getType(char)

      * @since   1.0.2

      */

     public static boolean isTitleCase(char ch) {

         return isTitleCase((int)ch);

     }

     /**

      * Determines if the specified character (Unicode code point) is a titlecase character.

      * <p>

      * A character is a titlecase character if its general

      * category type, provided by {@link Character#getType(int) getType(codePoint)},

      * is {@code TITLECASE_LETTER}.

      * <p>

      * Some characters look like pairs of Latin letters. For example, there

      * is an uppercase letter that looks like "LJ" and has a corresponding

      * lowercase letter that looks like "lj". A third form, which looks like "Lj",

      * is the appropriate form to use when rendering a word in lowercase

      * with initial capitals, as for a book title.

      * <p>

      * These are some of the Unicode characters for which this method returns

      * {@code true}:

      * <ul>

      * <li>{@code LATIN CAPITAL LETTER D WITH SMALL LETTER Z WITH CARON}

      * <li>{@code LATIN CAPITAL LETTER L WITH SMALL LETTER J}

      * <li>{@code LATIN CAPITAL LETTER N WITH SMALL LETTER J}

      * <li>{@code LATIN CAPITAL LETTER D WITH SMALL LETTER Z}

      * </ul>

      * <p> Many other Unicode characters are titlecase too.<p>

      *

      * @param   codePoint the character (Unicode code point) to be tested.

      * @return  {@code true} if the character is titlecase;

      *          {@code false} otherwise.

      * @see     Character#isLowerCase(int)

      * @see     Character#isUpperCase(int)

      * @see     Character#toTitleCase(int)

      * @see     Character#getType(int)

      * @since   1.5

      */

     public static boolean isTitleCase(int codePoint) {

         return getType(codePoint) == Character.TITLECASE_LETTER;

     }

     /**

      * Determines if the specified character is a digit.

      * <p>

      * A character is a digit if its general category type, provided

      * by {@code Character.getType(ch)}, is

      * {@code DECIMAL_DIGIT_NUMBER}.

      * <p>

      * Some Unicode character ranges that contain digits:

      * <ul>

      * <li>{@code '\u005Cu0030'} through {@code '\u005Cu0039'},

      *     ISO-LATIN-1 digits ({@code '0'} through {@code '9'})

      * <li>{@code '\u005Cu0660'} through {@code '\u005Cu0669'},

      *     Arabic-Indic digits

      * <li>{@code '\u005Cu06F0'} through {@code '\u005Cu06F9'},

      *     Extended Arabic-Indic digits

      * <li>{@code '\u005Cu0966'} through {@code '\u005Cu096F'},

      *     Devanagari digits

      * <li>{@code '\u005CuFF10'} through {@code '\u005CuFF19'},

      *     Fullwidth digits

      * </ul>

      *

      * Many other character ranges contain digits as well.

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #isDigit(int)} method.

      *

      * @param   ch   the character to be tested.

      * @return  {@code true} if the character is a digit;

      *          {@code false} otherwise.

      * @see     Character#digit(char, int)

      * @see     Character#forDigit(int, int)

      * @see     Character#getType(char)

      */

     public static boolean isDigit(char ch) {

         return String.valueOf(ch).matches("\\d");

     }

     /**

      * Determines if the specified character (Unicode code point) is a digit.

      * <p>

      * A character is a digit if its general category type, provided

      * by {@link Character#getType(int) getType(codePoint)}, is

      * {@code DECIMAL_DIGIT_NUMBER}.

      * <p>

      * Some Unicode character ranges that contain digits:

      * <ul>

      * <li>{@code '\u005Cu0030'} through {@code '\u005Cu0039'},

      *     ISO-LATIN-1 digits ({@code '0'} through {@code '9'})

      * <li>{@code '\u005Cu0660'} through {@code '\u005Cu0669'},

      *     Arabic-Indic digits

      * <li>{@code '\u005Cu06F0'} through {@code '\u005Cu06F9'},

      *     Extended Arabic-Indic digits

      * <li>{@code '\u005Cu0966'} through {@code '\u005Cu096F'},

      *     Devanagari digits

      * <li>{@code '\u005CuFF10'} through {@code '\u005CuFF19'},

      *     Fullwidth digits

      * </ul>

      *

      * Many other character ranges contain digits as well.

      *

      * @param   codePoint the character (Unicode code point) to be tested.

      * @return  {@code true} if the character is a digit;

      *          {@code false} otherwise.

      * @see     Character#forDigit(int, int)

      * @see     Character#getType(int)

      * @since   1.5

      */

     public static boolean isDigit(int codePoint) {

         return fromCodeChars(codePoint).matches("\\d");

     }

     @JavaScriptBody(args = "c", body = "return String.fromCharCode(c);")

     private native static String fromCodeChars(int codePoint);

     /**

      * Determines if a character is defined in Unicode.

      * <p>

      * A character is defined if at least one of the following is true:

      * <ul>

      * <li>It has an entry in the UnicodeData file.

      * <li>It has a value in a range defined by the UnicodeData file.

      * </ul>

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #isDefined(int)} method.

      *

      * @param   ch   the character to be tested

      * @return  {@code true} if the character has a defined meaning

      *          in Unicode; {@code false} otherwise.

      * @see     Character#isDigit(char)

      * @see     Character#isLetter(char)

      * @see     Character#isLetterOrDigit(char)

      * @see     Character#isLowerCase(char)

      * @see     Character#isTitleCase(char)

      * @see     Character#isUpperCase(char)

      * @since   1.0.2

      */

     public static boolean isDefined(char ch) {

         return isDefined((int)ch);

     }

     /**

      * Determines if a character (Unicode code point) is defined in Unicode.

      * <p>

      * A character is defined if at least one of the following is true:

      * <ul>

      * <li>It has an entry in the UnicodeData file.

      * <li>It has a value in a range defined by the UnicodeData file.

      * </ul>

      *

      * @param   codePoint the character (Unicode code point) to be tested.

      * @return  {@code true} if the character has a defined meaning

      *          in Unicode; {@code false} otherwise.

      * @see     Character#isDigit(int)

      * @see     Character#isLetter(int)

      * @see     Character#isLetterOrDigit(int)

      * @see     Character#isLowerCase(int)

      * @see     Character#isTitleCase(int)

      * @see     Character#isUpperCase(int)

      * @since   1.5

      */

     public static boolean isDefined(int codePoint) {

         return getType(codePoint) != Character.UNASSIGNED;

     }

     /**

      * Determines if the specified character is a letter.

      * <p>

      * A character is considered to be a letter if its general

      * category type, provided by {@code Character.getType(ch)},

      * is any of the following:

      * <ul>

      * <li> {@code UPPERCASE_LETTER}

      * <li> {@code LOWERCASE_LETTER}

      * <li> {@code TITLECASE_LETTER}

      * <li> {@code MODIFIER_LETTER}

      * <li> {@code OTHER_LETTER}

      * </ul>

      *

      * Not all letters have case. Many characters are

      * letters but are neither uppercase nor lowercase nor titlecase.

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #isLetter(int)} method.

      *

      * @param   ch   the character to be tested.

      * @return  {@code true} if the character is a letter;

      *          {@code false} otherwise.

      * @see     Character#isDigit(char)

      * @see     Character#isJavaIdentifierStart(char)

      * @see     Character#isJavaLetter(char)

      * @see     Character#isJavaLetterOrDigit(char)

      * @see     Character#isLetterOrDigit(char)

      * @see     Character#isLowerCase(char)

      * @see     Character#isTitleCase(char)

      * @see     Character#isUnicodeIdentifierStart(char)

      * @see     Character#isUpperCase(char)

      */

     public static boolean isLetter(char ch) {

         return String.valueOf(ch).matches("\\w") && !isDigit(ch);

     }

     /**

      * Determines if the specified character (Unicode code point) is a letter.

      * <p>

      * A character is considered to be a letter if its general

      * category type, provided by {@link Character#getType(int) getType(codePoint)},

      * is any of the following:

      * <ul>

      * <li> {@code UPPERCASE_LETTER}

      * <li> {@code LOWERCASE_LETTER}

      * <li> {@code TITLECASE_LETTER}

      * <li> {@code MODIFIER_LETTER}

      * <li> {@code OTHER_LETTER}

      * </ul>

      *

      * Not all letters have case. Many characters are

      * letters but are neither uppercase nor lowercase nor titlecase.

      *

      * @param   codePoint the character (Unicode code point) to be tested.

      * @return  {@code true} if the character is a letter;

      *          {@code false} otherwise.

      * @see     Character#isDigit(int)

      * @see     Character#isJavaIdentifierStart(int)

      * @see     Character#isLetterOrDigit(int)

      * @see     Character#isLowerCase(int)

      * @see     Character#isTitleCase(int)

      * @see     Character#isUnicodeIdentifierStart(int)

      * @see     Character#isUpperCase(int)

      * @since   1.5

      */

     public static boolean isLetter(int codePoint) {

         return fromCodeChars(codePoint).matches("\\w") && !isDigit(codePoint);

     }

     /**

      * Determines if the specified character is a letter or digit.

      * <p>

      * A character is considered to be a letter or digit if either

      * {@code Character.isLetter(char ch)} or

      * {@code Character.isDigit(char ch)} returns

      * {@code true} for the character.

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #isLetterOrDigit(int)} method.

      *

      * @param   ch   the character to be tested.

      * @return  {@code true} if the character is a letter or digit;

      *          {@code false} otherwise.

      * @see     Character#isDigit(char)

      * @see     Character#isJavaIdentifierPart(char)

      * @see     Character#isJavaLetter(char)

      * @see     Character#isJavaLetterOrDigit(char)

      * @see     Character#isLetter(char)

      * @see     Character#isUnicodeIdentifierPart(char)

      * @since   1.0.2

      */

     public static boolean isLetterOrDigit(char ch) {

         return String.valueOf(ch).matches("\\w");

     }

     /**

      * Determines if the specified character (Unicode code point) is a letter or digit.

      * <p>

      * A character is considered to be a letter or digit if either

      * {@link #isLetter(int) isLetter(codePoint)} or

      * {@link #isDigit(int) isDigit(codePoint)} returns

      * {@code true} for the character.

      *

      * @param   codePoint the character (Unicode code point) to be tested.

      * @return  {@code true} if the character is a letter or digit;

      *          {@code false} otherwise.

      * @see     Character#isDigit(int)

      * @see     Character#isJavaIdentifierPart(int)

      * @see     Character#isLetter(int)

      * @see     Character#isUnicodeIdentifierPart(int)

      * @since   1.5

      */

     public static boolean isLetterOrDigit(int codePoint) {

         return fromCodeChars(codePoint).matches("\\w");

     }

     static int getType(int x) {

         throw new UnsupportedOperationException();

     }

     /**

      * Determines if the specified character is

      * permissible as the first character in a Java identifier.

      * <p>

      * A character may start a Java identifier if and only if

      * one of the following conditions is true:

      * <ul>

      * <li> {@link #isLetter(char) isLetter(ch)} returns {@code true}

      * <li> {@link #getType(char) getType(ch)} returns {@code LETTER_NUMBER}

      * <li> {@code ch} is a currency symbol (such as {@code '$'})

      * <li> {@code ch} is a connecting punctuation character (such as {@code '_'}).

      * </ul>

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #isJavaIdentifierStart(int)} method.

      *

      * @param   ch the character to be tested.

      * @return  {@code true} if the character may start a Java identifier;

      *          {@code false} otherwise.

      * @see     Character#isJavaIdentifierPart(char)

      * @see     Character#isLetter(char)

      * @see     Character#isUnicodeIdentifierStart(char)

      * @see     javax.lang.model.SourceVersion#isIdentifier(CharSequence)

      * @since   1.1

      */

     public static boolean isJavaIdentifierStart(char ch) {

         return isJavaIdentifierStart((int)ch);

     }

     /**

      * Determines if the character (Unicode code point) is

      * permissible as the first character in a Java identifier.

      * <p>

      * A character may start a Java identifier if and only if

      * one of the following conditions is true:

      * <ul>

      * <li> {@link #isLetter(int) isLetter(codePoint)}

      *      returns {@code true}

      * <li> {@link #getType(int) getType(codePoint)}

      *      returns {@code LETTER_NUMBER}

      * <li> the referenced character is a currency symbol (such as {@code '$'})

      * <li> the referenced character is a connecting punctuation character

      *      (such as {@code '_'}).

      * </ul>

      *

      * @param   codePoint the character (Unicode code point) to be tested.

      * @return  {@code true} if the character may start a Java identifier;

      *          {@code false} otherwise.

      * @see     Character#isJavaIdentifierPart(int)

      * @see     Character#isLetter(int)

      * @see     Character#isUnicodeIdentifierStart(int)

      * @see     javax.lang.model.SourceVersion#isIdentifier(CharSequence)

      * @since   1.5

      */

     public static boolean isJavaIdentifierStart(int codePoint) {

         return 

             ('A' <= codePoint && codePoint <= 'Z') ||

             ('a' <= codePoint && codePoint <= 'z');

     }

     /**

      * Determines if the specified character may be part of a Java

      * identifier as other than the first character.

      * <p>

      * A character may be part of a Java identifier if any of the following

      * are true:

      * <ul>

      * <li>  it is a letter

      * <li>  it is a currency symbol (such as {@code '$'})

      * <li>  it is a connecting punctuation character (such as {@code '_'})

      * <li>  it is a digit

      * <li>  it is a numeric letter (such as a Roman numeral character)

      * <li>  it is a combining mark

      * <li>  it is a non-spacing mark

      * <li> {@code isIdentifierIgnorable} returns

      * {@code true} for the character

      * </ul>

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #isJavaIdentifierPart(int)} method.

      *

      * @param   ch      the character to be tested.

      * @return {@code true} if the character may be part of a

      *          Java identifier; {@code false} otherwise.

      * @see     Character#isIdentifierIgnorable(char)

      * @see     Character#isJavaIdentifierStart(char)

      * @see     Character#isLetterOrDigit(char)

      * @see     Character#isUnicodeIdentifierPart(char)

      * @see     javax.lang.model.SourceVersion#isIdentifier(CharSequence)

      * @since   1.1

      */

     public static boolean isJavaIdentifierPart(char ch) {

         return isJavaIdentifierPart((int)ch);

     }

     /**

      * Determines if the character (Unicode code point) may be part of a Java

      * identifier as other than the first character.

      * <p>

      * A character may be part of a Java identifier if any of the following

      * are true:

      * <ul>

      * <li>  it is a letter

      * <li>  it is a currency symbol (such as {@code '$'})

      * <li>  it is a connecting punctuation character (such as {@code '_'})

      * <li>  it is a digit

      * <li>  it is a numeric letter (such as a Roman numeral character)

      * <li>  it is a combining mark

      * <li>  it is a non-spacing mark

      * <li> {@link #isIdentifierIgnorable(int)

      * isIdentifierIgnorable(codePoint)} returns {@code true} for

      * the character

      * </ul>

      *

      * @param   codePoint the character (Unicode code point) to be tested.

      * @return {@code true} if the character may be part of a

      *          Java identifier; {@code false} otherwise.

      * @see     Character#isIdentifierIgnorable(int)

      * @see     Character#isJavaIdentifierStart(int)

      * @see     Character#isLetterOrDigit(int)

      * @see     Character#isUnicodeIdentifierPart(int)

      * @see     javax.lang.model.SourceVersion#isIdentifier(CharSequence)

      * @since   1.5

      */

     public static boolean isJavaIdentifierPart(int codePoint) {

         return isJavaIdentifierStart(codePoint) ||

             ('0' <= codePoint && codePoint <= '9') || codePoint == '$';

     }

     /**

      * Converts the character argument to lowercase using case

      * mapping information from the UnicodeData file.

      * <p>

      * Note that

      * {@code Character.isLowerCase(Character.toLowerCase(ch))}

      * does not always return {@code true} for some ranges of

      * characters, particularly those that are symbols or ideographs.

      *

      * <p>In general, {@link String#toLowerCase()} should be used to map

      * characters to lowercase. {@code String} case mapping methods

      * have several benefits over {@code Character} case mapping methods.

      * {@code String} case mapping methods can perform locale-sensitive

      * mappings, context-sensitive mappings, and 1:M character mappings, whereas

      * the {@code Character} case mapping methods cannot.

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #toLowerCase(int)} method.

      *

      * @param   ch   the character to be converted.

      * @return  the lowercase equivalent of the character, if any;

      *          otherwise, the character itself.

      * @see     Character#isLowerCase(char)

      * @see     String#toLowerCase()

      */

     public static char toLowerCase(char ch) {

         return String.valueOf(ch).toLowerCase().charAt(0);

     }

     /**

      * Converts the character argument to uppercase using case mapping

      * information from the UnicodeData file.

      * <p>

      * Note that

      * {@code Character.isUpperCase(Character.toUpperCase(ch))}

      * does not always return {@code true} for some ranges of

      * characters, particularly those that are symbols or ideographs.

      *

      * <p>In general, {@link String#toUpperCase()} should be used to map

      * characters to uppercase. {@code String} case mapping methods

      * have several benefits over {@code Character} case mapping methods.

      * {@code String} case mapping methods can perform locale-sensitive

      * mappings, context-sensitive mappings, and 1:M character mappings, whereas

      * the {@code Character} case mapping methods cannot.

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #toUpperCase(int)} method.

      *

      * @param   ch   the character to be converted.

      * @return  the uppercase equivalent of the character, if any;

      *          otherwise, the character itself.

      * @see     Character#isUpperCase(char)

      * @see     String#toUpperCase()

      */

     public static char toUpperCase(char ch) {

         return String.valueOf(ch).toUpperCase().charAt(0);

     }

     /**

      * Returns the numeric value of the character {@code ch} in the

      * specified radix.

      * <p>

      * If the radix is not in the range {@code MIN_RADIX} ≤

      * {@code radix} ≤ {@code MAX_RADIX} or if the

      * value of {@code ch} is not a valid digit in the specified

      * radix, {@code -1} is returned. A character is a valid digit

      * if at least one of the following is true:

      * <ul>

      * <li>The method {@code isDigit} is {@code true} of the character

      *     and the Unicode decimal digit value of the character (or its

      *     single-character decomposition) is less than the specified radix.

      *     In this case the decimal digit value is returned.

      * <li>The character is one of the uppercase Latin letters

      *     {@code 'A'} through {@code 'Z'} and its code is less than

      *     {@code radix + 'A' - 10}.

      *     In this case, {@code ch - 'A' + 10}

      *     is returned.

      * <li>The character is one of the lowercase Latin letters

      *     {@code 'a'} through {@code 'z'} and its code is less than

      *     {@code radix + 'a' - 10}.

      *     In this case, {@code ch - 'a' + 10}

      *     is returned.

      * <li>The character is one of the fullwidth uppercase Latin letters A

      *     ({@code '\u005CuFF21'}) through Z ({@code '\u005CuFF3A'})

      *     and its code is less than

      *     {@code radix + '\u005CuFF21' - 10}.

      *     In this case, {@code ch - '\u005CuFF21' + 10}

      *     is returned.

      * <li>The character is one of the fullwidth lowercase Latin letters a

      *     ({@code '\u005CuFF41'}) through z ({@code '\u005CuFF5A'})

      *     and its code is less than

      *     {@code radix + '\u005CuFF41' - 10}.

      *     In this case, {@code ch - '\u005CuFF41' + 10}

      *     is returned.

      * </ul>

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #digit(int, int)} method.

      *

      * @param   ch      the character to be converted.

      * @param   radix   the radix.

      * @return  the numeric value represented by the character in the

      *          specified radix.

      * @see     Character#forDigit(int, int)

      * @see     Character#isDigit(char)

      */

     public static int digit(char ch, int radix) {

         return digit((int)ch, radix);

     }

     /**

      * Returns the numeric value of the specified character (Unicode

      * code point) in the specified radix.

      *

      * <p>If the radix is not in the range {@code MIN_RADIX} &le;

      * {@code radix} ≤ {@code MAX_RADIX} or if the

      * character is not a valid digit in the specified

      * radix, {@code -1} is returned. A character is a valid digit

      * if at least one of the following is true:

      * <ul>

      * <li>The method {@link #isDigit(int) isDigit(codePoint)} is {@code true} of the character

      *     and the Unicode decimal digit value of the character (or its

      *     single-character decomposition) is less than the specified radix.

      *     In this case the decimal digit value is returned.

      * <li>The character is one of the uppercase Latin letters

      *     {@code 'A'} through {@code 'Z'} and its code is less than

      *     {@code radix + 'A' - 10}.

      *     In this case, {@code codePoint - 'A' + 10}

      *     is returned.

      * <li>The character is one of the lowercase Latin letters

      *     {@code 'a'} through {@code 'z'} and its code is less than

      *     {@code radix + 'a' - 10}.

      *     In this case, {@code codePoint - 'a' + 10}

      *     is returned.

      * <li>The character is one of the fullwidth uppercase Latin letters A

      *     ({@code '\u005CuFF21'}) through Z ({@code '\u005CuFF3A'})

      *     and its code is less than

      *     {@code radix + '\u005CuFF21' - 10}.

      *     In this case,

      *     {@code codePoint - '\u005CuFF21' + 10}

      *     is returned.

      * <li>The character is one of the fullwidth lowercase Latin letters a

      *     ({@code '\u005CuFF41'}) through z ({@code '\u005CuFF5A'})

      *     and its code is less than

      *     {@code radix + '\u005CuFF41'- 10}.

      *     In this case,

      *     {@code codePoint - '\u005CuFF41' + 10}

      *     is returned.

      * </ul>

      *

      * @param   codePoint the character (Unicode code point) to be converted.

      * @param   radix   the radix.

      * @return  the numeric value represented by the character in the

      *          specified radix.

      * @see     Character#forDigit(int, int)

      * @see     Character#isDigit(int)

      * @since   1.5

      */

     @JavaScriptBody(args = { "codePoint", "radix" }, body=

         "var x = parseInt(String.fromCharCode(codePoint), radix);\n"

       + "return isNaN(x) ? -1 : x;"

     )

     public static int digit(int codePoint, int radix) {

         throw new UnsupportedOperationException();

     }

     /**

      * Returns the {@code int} value that the specified Unicode

      * character represents. For example, the character

      * {@code '\u005Cu216C'} (the roman numeral fifty) will return

      * an int with a value of 50.

      * <p>

      * The letters A-Z in their uppercase ({@code '\u005Cu0041'} through

      * {@code '\u005Cu005A'}), lowercase

      * ({@code '\u005Cu0061'} through {@code '\u005Cu007A'}), and

      * full width variant ({@code '\u005CuFF21'} through

      * {@code '\u005CuFF3A'} and {@code '\u005CuFF41'} through

      * {@code '\u005CuFF5A'}) forms have numeric values from 10

      * through 35. This is independent of the Unicode specification,

      * which does not assign numeric values to these {@code char}

      * values.

      * <p>

      * If the character does not have a numeric value, then -1 is returned.

      * If the character has a numeric value that cannot be represented as a

      * nonnegative integer (for example, a fractional value), then -2

      * is returned.

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #getNumericValue(int)} method.

      *

      * @param   ch      the character to be converted.

      * @return  the numeric value of the character, as a nonnegative {@code int}

      *           value; -2 if the character has a numeric value that is not a

      *          nonnegative integer; -1 if the character has no numeric value.

      * @see     Character#forDigit(int, int)

      * @see     Character#isDigit(char)

      * @since   1.1

      */

     public static int getNumericValue(char ch) {

         return getNumericValue((int)ch);

     }

     /**

      * Returns the {@code int} value that the specified

      * character (Unicode code point) represents. For example, the character

      * {@code '\u005Cu216C'} (the Roman numeral fifty) will return

      * an {@code int} with a value of 50.

      * <p>

      * The letters A-Z in their uppercase ({@code '\u005Cu0041'} through

      * {@code '\u005Cu005A'}), lowercase

      * ({@code '\u005Cu0061'} through {@code '\u005Cu007A'}), and

      * full width variant ({@code '\u005CuFF21'} through

      * {@code '\u005CuFF3A'} and {@code '\u005CuFF41'} through

      * {@code '\u005CuFF5A'}) forms have numeric values from 10

      * through 35. This is independent of the Unicode specification,

      * which does not assign numeric values to these {@code char}

      * values.

      * <p>

      * If the character does not have a numeric value, then -1 is returned.

      * If the character has a numeric value that cannot be represented as a

      * nonnegative integer (for example, a fractional value), then -2

      * is returned.

      *

      * @param   codePoint the character (Unicode code point) to be converted.

      * @return  the numeric value of the character, as a nonnegative {@code int}

      *          value; -2 if the character has a numeric value that is not a

      *          nonnegative integer; -1 if the character has no numeric value.

      * @see     Character#forDigit(int, int)

      * @see     Character#isDigit(int)

      * @since   1.5

      */

     public static int getNumericValue(int codePoint) {

         throw new UnsupportedOperationException();

     }

     /**

      * Determines if the specified character is ISO-LATIN-1 white space.

      * This method returns {@code true} for the following five

      * characters only:

      * <table>

      * <tr><td>{@code '\t'}</td>            <td>{@code U+0009}</td>

      *     <td>{@code HORIZONTAL TABULATION}</td></tr>

      * <tr><td>{@code '\n'}</td>            <td>{@code U+000A}</td>

      *     <td>{@code NEW LINE}</td></tr>

      * <tr><td>{@code '\f'}</td>            <td>{@code U+000C}</td>

      *     <td>{@code FORM FEED}</td></tr>

      * <tr><td>{@code '\r'}</td>            <td>{@code U+000D}</td>

      *     <td>{@code CARRIAGE RETURN}</td></tr>

      * <tr><td>{@code '&nbsp;'}</td>  <td>{@code U+0020}</td>

      *     <td>{@code SPACE}</td></tr>

      * </table>

      *

      * @param      ch   the character to be tested.

      * @return     {@code true} if the character is ISO-LATIN-1 white

      *             space; {@code false} otherwise.

      * @see        Character#isSpaceChar(char)

      * @see        Character#isWhitespace(char)

      * @deprecated Replaced by isWhitespace(char).

      */

     @Deprecated

     public static boolean isSpace(char ch) {

         return (ch <= 0x0020) &&

             (((((1L << 0x0009) |

             (1L << 0x000A) |

             (1L << 0x000C) |

             (1L << 0x000D) |

             (1L << 0x0020)) >> ch) & 1L) != 0);

     }

     /**

      * Determines if the specified character is white space according to Java.

      * A character is a Java whitespace character if and only if it satisfies

      * one of the following criteria:

      * <ul>

      * <li> It is a Unicode space character ({@code SPACE_SEPARATOR},

      *      {@code LINE_SEPARATOR}, or {@code PARAGRAPH_SEPARATOR})

      *      but is not also a non-breaking space ({@code '\u005Cu00A0'},

      *      {@code '\u005Cu2007'}, {@code '\u005Cu202F'}).

      * <li> It is {@code '\u005Ct'}, U+0009 HORIZONTAL TABULATION.

      * <li> It is {@code '\u005Cn'}, U+000A LINE FEED.

      * <li> It is {@code '\u005Cu000B'}, U+000B VERTICAL TABULATION.

      * <li> It is {@code '\u005Cf'}, U+000C FORM FEED.

      * <li> It is {@code '\u005Cr'}, U+000D CARRIAGE RETURN.

      * <li> It is {@code '\u005Cu001C'}, U+001C FILE SEPARATOR.

      * <li> It is {@code '\u005Cu001D'}, U+001D GROUP SEPARATOR.

      * <li> It is {@code '\u005Cu001E'}, U+001E RECORD SEPARATOR.

      * <li> It is {@code '\u005Cu001F'}, U+001F UNIT SEPARATOR.

      * </ul>

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #isWhitespace(int)} method.

      *

      * @param   ch the character to be tested.

      * @return  {@code true} if the character is a Java whitespace

      *          character; {@code false} otherwise.

      * @see     Character#isSpaceChar(char)

      * @since   1.1

      */

     public static boolean isWhitespace(char ch) {

         return isWhitespace((int)ch);

     }

     /**

      * Determines if the specified character (Unicode code point) is

      * white space according to Java.  A character is a Java

      * whitespace character if and only if it satisfies one of the

      * following criteria:

      * <ul>

      * <li> It is a Unicode space character ({@link #SPACE_SEPARATOR},

      *      {@link #LINE_SEPARATOR}, or {@link #PARAGRAPH_SEPARATOR})

      *      but is not also a non-breaking space ({@code '\u005Cu00A0'},

      *      {@code '\u005Cu2007'}, {@code '\u005Cu202F'}).

      * <li> It is {@code '\u005Ct'}, U+0009 HORIZONTAL TABULATION.

      * <li> It is {@code '\u005Cn'}, U+000A LINE FEED.

      * <li> It is {@code '\u005Cu000B'}, U+000B VERTICAL TABULATION.

      * <li> It is {@code '\u005Cf'}, U+000C FORM FEED.

      * <li> It is {@code '\u005Cr'}, U+000D CARRIAGE RETURN.

      * <li> It is {@code '\u005Cu001C'}, U+001C FILE SEPARATOR.

      * <li> It is {@code '\u005Cu001D'}, U+001D GROUP SEPARATOR.

      * <li> It is {@code '\u005Cu001E'}, U+001E RECORD SEPARATOR.

      * <li> It is {@code '\u005Cu001F'}, U+001F UNIT SEPARATOR.

      * </ul>

      * <p>

      *

      * @param   codePoint the character (Unicode code point) to be tested.

      * @return  {@code true} if the character is a Java whitespace

      *          character; {@code false} otherwise.

      * @see     Character#isSpaceChar(int)

      * @since   1.5

      */

     public static boolean isWhitespace(int codePoint) {

         throw new UnsupportedOperationException();

     }

     /**

      * Determines if the specified character is an ISO control

      * character.  A character is considered to be an ISO control

      * character if its code is in the range {@code '\u005Cu0000'}

      * through {@code '\u005Cu001F'} or in the range

      * {@code '\u005Cu007F'} through {@code '\u005Cu009F'}.

      *

      * <p><b>Note:</b> This method cannot handle <a

      * href="#supplementary"> supplementary characters</a>. To support

      * all Unicode characters, including supplementary characters, use

      * the {@link #isISOControl(int)} method.

      *

      * @param   ch      the character to be tested.

      * @return  {@code true} if the character is an ISO control character;

      *          {@code false} otherwise.

      *

      * @see     Character#isSpaceChar(char)

      * @see     Character#isWhitespace(char)

      * @since   1.1

      */

     public static boolean isISOControl(char ch) {

         return isISOControl((int)ch);

     }

     /**

      * Determines if the referenced character (Unicode code point) is an ISO control

      * character.  A character is considered to be an ISO control

      * character if its code is in the range {@code '\u005Cu0000'}

      * through {@code '\u005Cu001F'} or in the range

      * {@code '\u005Cu007F'} through {@code '\u005Cu009F'}.

      *

      * @param   codePoint the character (Unicode code point) to be tested.

      * @return  {@code true} if the character is an ISO control character;

      *          {@code false} otherwise.

      * @see     Character#isSpaceChar(int)

      * @see     Character#isWhitespace(int)

      * @since   1.5

      */

     public static boolean isISOControl(int codePoint) {

         // Optimized form of:

         //     (codePoint >= 0x00 && codePoint <= 0x1F) ||

         //     (codePoint >= 0x7F && codePoint <= 0x9F);

         return codePoint <= 0x9F &&

             (codePoint >= 0x7F || (codePoint >>> 5 == 0));

     }

     /**

      * Determines the character representation for a specific digit in

      * the specified radix. If the value of {@code radix} is not a

      * valid radix, or the value of {@code digit} is not a valid

      * digit in the specified radix, the null character

      * ({@code '\u005Cu0000'}) is returned.

      * <p>

      * The {@code radix} argument is valid if it is greater than or

      * equal to {@code MIN_RADIX} and less than or equal to

      * {@code MAX_RADIX}. The {@code digit} argument is valid if

      * {@code 0 <= digit < radix}.

      * <p>

      * If the digit is less than 10, then

      * {@code '0' + digit} is returned. Otherwise, the value

      * {@code 'a' + digit - 10} is returned.

      *

      * @param   digit   the number to convert to a character.

      * @param   radix   the radix.

      * @return  the {@code char} representation of the specified digit

      *          in the specified radix.

      * @see     Character#MIN_RADIX

      * @see     Character#MAX_RADIX

      * @see     Character#digit(char, int)

      */

     public static char forDigit(int digit, int radix) {

         if ((digit >= radix) || (digit < 0)) {

             return '\0';

         }

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

             return '\0';

         }

         if (digit < 10) {

             return (char)('0' + digit);

         }

         return (char)('a' - 10 + digit);

     }

     /**

      * Compares two {@code Character} objects numerically.

      *

      * @param   anotherCharacter   the {@code Character} to be compared.

      * @return  the value {@code 0} if the argument {@code Character}

      *          is equal to this {@code Character}; a value less than

      *          {@code 0} if this {@code Character} is numerically less

      *          than the {@code Character} argument; and a value greater than

      *          {@code 0} if this {@code Character} is numerically greater

      *          than the {@code Character} argument (unsigned comparison).

      *          Note that this is strictly a numerical comparison; it is not

      *          locale-dependent.

      * @since   1.2

      */

     public int compareTo(Character anotherCharacter) {

         return compare(this.value, anotherCharacter.value);

     }

     /**

      * Compares two {@code char} values numerically.

      * The value returned is identical to what would be returned by:

      * <pre>

      *    Character.valueOf(x).compareTo(Character.valueOf(y))

      * </pre>

      *

      * @param  x the first {@code char} to compare

      * @param  y the second {@code char} to compare

      * @return the value {@code 0} if {@code x == y};

      *         a value less than {@code 0} if {@code x < y}; and

      *         a value greater than {@code 0} if {@code x > y}

      * @since 1.7

      */

     public static int compare(char x, char y) {

         return x - y;

     }

     /**

      * The number of bits used to represent a <tt>char</tt> value in unsigned

      * binary form, constant {@code 16}.

      *

      * @since 1.5

      */

     public static final int SIZE = 16;

     /**

      * Returns the value obtained by reversing the order of the bytes in the

      * specified <tt>char</tt> value.

      *

      * @return the value obtained by reversing (or, equivalently, swapping)

      *     the bytes in the specified <tt>char</tt> value.

      * @since 1.5

      */

     public static char reverseBytes(char ch) {

         return (char) (((ch & 0xFF00) >> 8) | (ch << 8));

     }

 }