/* String.java -- immutable character sequences; the object of string literals
   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2005
   Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath 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 for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


import gnu.java.lang.CharData;

import java.io.Serializable;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CodingErrorAction;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;
import java.text.Collator;
import java.util.Comparator;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

/**
 * Strings represent an immutable set of characters.  All String literals
 * are instances of this class, and two string literals with the same contents
 * refer to the same String object.
 *
 * <p>This class also includes a number of methods for manipulating the
 * contents of strings (of course, creating a new object if there are any
 * changes, as String is immutable). Case mapping relies on Unicode 3.0.0
 * standards, where some character sequences have a different number of
 * characters in the uppercase version than the lower case.
 *
 * <p>Strings are special, in that they are the only object with an overloaded
 * operator. When you use '+' with at least one String argument, both
 * arguments have String conversion performed on them, and another String (not
 * guaranteed to be unique) results.
 *
 * <p>String is special-cased when doing data serialization - rather than
 * listing the fields of this class, a String object is converted to a string
 * literal in the object stream.
 *
 * @author Paul N. Fisher
 * @author Eric Blake (ebb9@email.byu.edu)
 * @author Per Bothner (bothner@cygnus.com)
 * @since 1.0
 * @status updated to 1.4; but could use better data sharing via offset field
 */

public final class StressClass
    implements java.io.Serializable, Comparable<String>, CharSequence
{
  // WARNING: String is a CORE class in the bootstrap cycle. See the comments
  // in vm/reference/java/lang/Runtime for implications of this fact.

  /**
   * This is probably not necessary because this class is special cased already
   * but it will avoid showing up as a discrepancy when comparing SUIDs.
   */
  private static final long serialVersionUID = -6849794470754667710L;

  /**
   * Stores unicode multi-character uppercase expansion table.
   * @see #toUpperCase(char)
   * @see CharData#UPPER_EXPAND
   */
  private static final char[] upperExpand
	= zeroBasedStringValue(CharData.UPPER_EXPAND);

  /**
   * Stores unicode multi-character uppercase special casing table.
   * @see #upperCaseExpansion(char)
   * @see CharData#UPPER_SPECIAL
   */
  private static final char[] upperSpecial
	  = zeroBasedStringValue(CharData.UPPER_SPECIAL);
  
  /**
   * Characters which make up the String.
   * Package access is granted for use by StringBuffer.
   */
  final char[] value;

  /**
   * Holds the number of characters in value.  This number is generally
   * the same as value.length, but can be smaller because substrings and
   * StringBuffers can share arrays. Package visible for use by trusted code.
   */
  final int count;

  /**
   * Caches the result of hashCode().  If this value is zero, the hashcode
   * is considered uncached (even if 0 is the correct hash value).
   */
  private int cachedHashCode;

  /**
   * Holds the starting position for characters in value[].  Since
   * substring()'s are common, the use of offset allows the operation
   * to perform in O(1). Package access is granted for use by StringBuffer.
   */
  final int offset;

  /**
   * An implementation for {@link CASE_INSENSITIVE_ORDER}.
   * This must be {@link Serializable}. The class name is dictated by
   * compatibility with Sun's JDK.
   */
  private static final class CaseInsensitiveComparator
    implements Comparator, Serializable
  {
    /**
     * Compatible with JDK 1.2.
     */
    private static final long serialVersionUID = 8575799808933029326L;

    /**
     * The default private constructor generates unnecessary overhead.
     */
    CaseInsensitiveComparator() {}

    /**
     * Compares to Strings, using
     * <code>String.compareToIgnoreCase(String)</code>.
     *
     * @param o1 the first string
     * @param o2 the second string
     * @return &lt; 0, 0, or &gt; 0 depending on the case-insensitive
     *         comparison of the two strings.
     * @throws NullPointerException if either argument is null
     * @throws ClassCastException if either argument is not a String
     * @see #compareToIgnoreCase(String)
     */
    public int compare(Object o1, Object o2)
    {
      return ((String) o1).compareToIgnoreCase((String) o2);
    }
  } // class CaseInsensitiveComparator

  /**
   * A Comparator that uses <code>String.compareToIgnoreCase(String)</code>.
   * This comparator is {@link Serializable}. Note that it ignores Locale,
   * for that, you want a Collator.
   *
   * @see Collator#compare(String, String)
   * @since 1.2
   */
  public static final Comparator CASE_INSENSITIVE_ORDER
    = new CaseInsensitiveComparator();

  /**
   * Creates an empty String (length 0). Unless you really need a new object,
   * consider using <code>""</code> instead.
   */
  public String()
  {
    value = "".value;
    offset = 0;
    count = 0;
  }

  /**
   * Copies the contents of a String to a new String. Since Strings are
   * immutable, only a shallow copy is performed.
   *
   * @param str String to copy
   * @throws NullPointerException if value is null
   */
  public String(String str)
  {
    value = str.value;
    offset = str.offset;
    count = str.count;
    cachedHashCode = str.cachedHashCode;
  }

  /**
   * Creates a new String using the character sequence of the char array.
   * Subsequent changes to data do not affect the String.
   *
   * @param data char array to copy
   * @throws NullPointerException if data is null
   */
  public String(char[] data)
  {
    this(data, 0, data.length, false);
  }

  /**
   * Creates a new String using the character sequence of a subarray of
   * characters. The string starts at offset, and copies count chars.
   * Subsequent changes to data do not affect the String.
   *
   * @param data char array to copy
   * @param offset position (base 0) to start copying out of data
   * @param count the number of characters from data to copy
   * @throws NullPointerException if data is null
   * @throws IndexOutOfBoundsException if (offset &lt; 0 || count &lt; 0
   *         || offset + count &gt; data.length)
   *         (while unspecified, this is a StringIndexOutOfBoundsException)
   */
  public String(char[] data, int offset, int count)
  {
    this(data, offset, count, false);
  }

  /**
   * Creates a new String using an 8-bit array of integer values, starting at
   * an offset, and copying up to the count. Each character c, using
   * corresponding byte b, is created in the new String as if by performing:
   *
   * <pre>
   * c = (char) (((hibyte &amp; 0xff) &lt;&lt; 8) | (b &amp; 0xff))
   * </pre>
   *
   * @param ascii array of integer values
   * @param hibyte top byte of each Unicode character
   * @param offset position (base 0) to start copying out of ascii
   * @param count the number of characters from ascii to copy
   * @throws NullPointerException if ascii is null
   * @throws IndexOutOfBoundsException if (offset &lt; 0 || count &lt; 0
   *         || offset + count &gt; ascii.length)
   *         (while unspecified, this is a StringIndexOutOfBoundsException)
   * @see #String(byte[])
   * @see #String(byte[], String)
   * @see #String(byte[], int, int)
   * @see #String(byte[], int, int, String)
   * @deprecated use {@link #String(byte[], int, int, String)} to perform
   *             correct encoding
   */
  public String(byte[] ascii, int hibyte, int offset, int count)
  {
    if (offset < 0 || count < 0 || offset + count > ascii.length)
      throw new StringIndexOutOfBoundsException();
    value = new char[count];
    this.offset = 0;
    this.count = count;
    hibyte <<= 8;
    offset += count;
    while (--count >= 0)
      value[count] = (char) (hibyte | (ascii[--offset] & 0xff));
  }

  /**
   * Creates a new String using an 8-bit array of integer values. Each
   * character c, using corresponding byte b, is created in the new String
   * as if by performing:
   *
   * <pre>
   * c = (char) (((hibyte &amp; 0xff) &lt;&lt; 8) | (b &amp; 0xff))
   * </pre>
   *
   * @param ascii array of integer values
   * @param hibyte top byte of each Unicode character
   * @throws NullPointerException if ascii is null
   * @see #String(byte[])
   * @see #String(byte[], String)
   * @see #String(byte[], int, int)
   * @see #String(byte[], int, int, String)
   * @see #String(byte[], int, int, int)
   * @deprecated use {@link #String(byte[], String)} to perform
   *             correct encoding
   */
  public String(byte[] ascii, int hibyte)
  {
    this(ascii, hibyte, 0, ascii.length);
  }

  /**
   * Creates a new String using the portion of the byte array starting at the
   * offset and ending at offset + count. Uses the specified encoding type
   * to decode the byte array, so the resulting string may be longer or
   * shorter than the byte array. For more decoding control, use
   * {@link java.nio.charset.CharsetDecoder}, and for valid character sets,
   * see {@link java.nio.charset.Charset}. The behavior is not specified if
   * the decoder encounters invalid characters; this implementation throws
   * an Error.
   *
   * @param data byte array to copy
   * @param offset the offset to start at
   * @param count the number of bytes in the array to use
   * @param encoding the name of the encoding to use
   * @throws NullPointerException if data or encoding is null
   * @throws IndexOutOfBoundsException if offset or count is incorrect
   *         (while unspecified, this is a StringIndexOutOfBoundsException)
   * @throws UnsupportedEncodingException if encoding is not found
   * @throws Error if the decoding fails
   * @since 1.1
   */
  public String(byte[] data, int offset, int count, String encoding)
    throws UnsupportedEncodingException
  {
    if (offset < 0 || count < 0 || offset + count > data.length)
      throw new StringIndexOutOfBoundsException();
    try 
      {
        CharsetDecoder csd = Charset.forName(encoding).newDecoder();
	csd.onMalformedInput(CodingErrorAction.REPLACE);
	csd.onUnmappableCharacter(CodingErrorAction.REPLACE);
	CharBuffer cbuf = csd.decode(ByteBuffer.wrap(data, offset, count));
 	if(cbuf.hasArray())
 	  {
 	    value = cbuf.array();
	    this.offset = cbuf.position();
	    this.count = cbuf.remaining();
 	  } else {
	    // Doubt this will happen. But just in case.
	    value = new char[cbuf.remaining()];
	    cbuf.get(value);
	    this.offset = 0;
	    this.count = value.length;
	  }
      } catch(CharacterCodingException e){
	  throw new UnsupportedEncodingException("Encoding: "+encoding+
						 " not found.");	  
      } catch(IllegalCharsetNameException e){
	  throw new UnsupportedEncodingException("Encoding: "+encoding+
						 " not found.");
      } catch(UnsupportedCharsetException e){
	  throw new UnsupportedEncodingException("Encoding: "+encoding+
						 " not found.");
      }    
  }

  /**
   * Creates a new String using the byte array. Uses the specified encoding
   * type to decode the byte array, so the resulting string may be longer or
   * shorter than the byte array. For more decoding control, use
   * {@link java.nio.charset.CharsetDecoder}, and for valid character sets,
   * see {@link java.nio.charset.Charset}. The behavior is not specified if
   * the decoder encounters invalid characters; this implementation throws
   * an Error.
   *
   * @param data byte array to copy
   * @param encoding the name of the encoding to use
   * @throws NullPointerException if data or encoding is null
   * @throws UnsupportedEncodingException if encoding is not found
   * @throws Error if the decoding fails
   * @see #String(byte[], int, int, String)
   * @since 1.1
   */
  public String(byte[] data, String encoding)
    throws UnsupportedEncodingException
  {
    this(data, 0, data.length, encoding);
  }

  /**
   * Creates a new String using the portion of the byte array starting at the
   * offset and ending at offset + count. Uses the encoding of the platform's
   * default charset, so the resulting string may be longer or shorter than
   * the byte array. For more decoding control, use
   * {@link java.nio.charset.CharsetDecoder}.  The behavior is not specified
   * if the decoder encounters invalid characters; this implementation throws
   * an Error.
   *
   * @param data byte array to copy
   * @param offset the offset to start at
   * @param count the number of bytes in the array to use
   * @throws NullPointerException if data is null
   * @throws IndexOutOfBoundsException if offset or count is incorrect
   * @throws Error if the decoding fails
   * @see #String(byte[], int, int, String)
   * @since 1.1
   */
  public String(byte[] data, int offset, int count)
  {
    if (offset < 0 || count < 0 || offset + count > data.length)
      throw new StringIndexOutOfBoundsException();
    int o, c;
    char[] v;
    String encoding;
    try 
	{
	  encoding = System.getProperty("file.encoding");
	  CharsetDecoder csd = Charset.forName(encoding).newDecoder();
	  csd.onMalformedInput(CodingErrorAction.REPLACE);
	  csd.onUnmappableCharacter(CodingErrorAction.REPLACE);
	  CharBuffer cbuf = csd.decode(ByteBuffer.wrap(data, offset, count));
	  if(cbuf.hasArray())
	    {
              v = cbuf.array();
	      o = cbuf.position();
	      c = cbuf.remaining();
	    } else {
	      // Doubt this will happen. But just in case.
	      v = new char[cbuf.remaining()];
	      cbuf.get(v);
	      o = 0;
	      c = v.length;
	    }
	} catch(Exception ex){
	    // If anything goes wrong (System property not set,
	    // NIO provider not available, etc)
	    // Default to the 'safe' encoding ISO8859_1
	    v = new char[count];
	    o = 0;
	    c = count;
	    for (int i=0;i<count;i++)
	      v[i] = (char)data[offset+i];
	}
    this.value = v;
    this.offset = o;
    this.count = c;
  }

  /**
   * Creates a new String using the byte array. Uses the encoding of the
   * platform's default charset, so the resulting string may be longer or
   * shorter than the byte array. For more decoding control, use
   * {@link java.nio.charset.CharsetDecoder}.  The behavior is not specified
   * if the decoder encounters invalid characters; this implementation throws
   * an Error.
   *
   * @param data byte array to copy
   * @throws NullPointerException if data is null
   * @throws Error if the decoding fails
   * @see #String(byte[], int, int)
   * @see #String(byte[], int, int, String)
   * @since 1.1
   */
  public String(byte[] data)
  {
    this(data, 0, data.length);
  }

  /**
   * Creates a new String using the character sequence represented by
   * the StringBuffer. Subsequent changes to buf do not affect the String.
   *
   * @param buffer StringBuffer to copy
   * @throws NullPointerException if buffer is null
   */
  public String(StringBuffer buffer)
  {
    synchronized (buffer)
      {
        offset = 0;
        count = buffer.count;
        // Share unless buffer is 3/4 empty.
        if ((count << 2) < buffer.value.length)
          {
            value = new char[count];
            VMSystem.arraycopy(buffer.value, 0, value, 0, count);
          }
        else
          {
            buffer.shared = true;
            value = buffer.value;
          }
      }
  }

  /**
   * Creates a new String using the character sequence represented by
   * the StringBuilder. Subsequent changes to buf do not affect the String.
   *
   * @param buffer StringBuilder to copy
   * @throws NullPointerException if buffer is null
   */
  public String(StringBuilder buffer)
  {
    this(buffer.value, 0, buffer.count);
  }

  /**
   * Special constructor which can share an array when safe to do so.
   *
   * @param data the characters to copy
   * @param offset the location to start from
   * @param count the number of characters to use
   * @param dont_copy true if the array is trusted, and need not be copied
   * @throws NullPointerException if chars is null
   * @throws StringIndexOutOfBoundsException if bounds check fails
   */
  String(char[] data, int offset, int count, boolean dont_copy)
  {
    if (offset < 0 || count < 0 || offset + count > data.length)
      throw new StringIndexOutOfBoundsException();
    if (dont_copy)
      {
        value = data;
        this.offset = offset;
      }
    else
      {
        value = new char[count];
        VMSystem.arraycopy(data, offset, value, 0, count);
        this.offset = 0;
      }
    this.count = count;
  }

  /**
   * Returns the number of characters contained in this String.
   *
   * @return the length of this String
   */
  public int length()
  {
    return count;
  }

  /**
   * Returns the character located at the specified index within this String.
   *
   * @param index position of character to return (base 0)
   * @return character located at position index
   * @throws IndexOutOfBoundsException if index &lt; 0 || index &gt;= length()
   *         (while unspecified, this is a StringIndexOutOfBoundsException)
   */
  public char charAt(int index)
  {
    if (index < 0 || index >= count)
      throw new StringIndexOutOfBoundsException(index);
    return value[offset + index];
  }

  /**
   * Copies characters from this String starting at a specified start index,
   * ending at a specified stop index, to a character array starting at
   * a specified destination begin index.
   *
   * @param srcBegin index to begin copying characters from this String
   * @param srcEnd index after the last character to be copied from this String
   * @param dst character array which this String is copied into
   * @param dstBegin index to start writing characters into dst
   * @throws NullPointerException if dst is null
   * @throws IndexOutOfBoundsException if any indices are out of bounds
   *         (while unspecified, source problems cause a
   *         StringIndexOutOfBoundsException, and dst problems cause an
   *         ArrayIndexOutOfBoundsException)
   */
  public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin)
  {
    if (srcBegin < 0 || srcBegin > srcEnd || srcEnd > count)
      throw new StringIndexOutOfBoundsException();
    VMSystem.arraycopy(value, srcBegin + offset,
                     dst, dstBegin, srcEnd - srcBegin);
  }

  /**
   * Copies the low byte of each character from this String starting at a
   * specified start index, ending at a specified stop index, to a byte array
   * starting at a specified destination begin index.
   *
   * @param srcBegin index to being copying characters from this String
   * @param srcEnd index after the last character to be copied from this String
   * @param dst byte array which each low byte of this String is copied into
   * @param dstBegin index to start writing characters into dst
   * @throws NullPointerException if dst is null and copy length is non-zero
   * @throws IndexOutOfBoundsException if any indices are out of bounds
   *         (while unspecified, source problems cause a
   *         StringIndexOutOfBoundsException, and dst problems cause an
   *         ArrayIndexOutOfBoundsException)
   * @see #getBytes()
   * @see #getBytes(String)
   * @deprecated use {@link #getBytes()}, which uses a char to byte encoder
   */
  public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin)
  {
    if (srcBegin < 0 || srcBegin > srcEnd || srcEnd > count)
      throw new StringIndexOutOfBoundsException();
    int i = srcEnd - srcBegin;
    srcBegin += offset;
    while (--i >= 0)
      dst[dstBegin++] = (byte) value[srcBegin++];
  }

  /**
   * Converts the Unicode characters in this String to a byte array. Uses the
   * specified encoding method, so the result may be longer or shorter than
   * the String. For more encoding control, use
   * {@link java.nio.charset.CharsetEncoder}, and for valid character sets,
   * see {@link java.nio.charset.Charset}. Unsupported characters get
   * replaced by an encoding specific byte.
   *
   * @param enc encoding name
   * @return the resulting byte array
   * @throws NullPointerException if enc is null
   * @throws UnsupportedEncodingException if encoding is not supported
   * @since 1.1
   */
  public byte[] getBytes(String enc) throws UnsupportedEncodingException
  {
    try 
      {
	CharsetEncoder cse = Charset.forName(enc).newEncoder();
	cse.onMalformedInput(CodingErrorAction.REPLACE);
	cse.onUnmappableCharacter(CodingErrorAction.REPLACE);
	ByteBuffer bbuf = cse.encode(CharBuffer.wrap(value, offset, count));
	if(bbuf.hasArray())
	  return bbuf.array();

	// Doubt this will happen. But just in case.
	byte[] bytes = new byte[bbuf.remaining()];
	bbuf.get(bytes);
	return bytes;

      } catch(IllegalCharsetNameException e){
	  throw new UnsupportedEncodingException("Encoding: "+enc+
						 " not found.");
      } catch(UnsupportedCharsetException e){
	  throw new UnsupportedEncodingException("Encoding: "+enc+
						 " not found.");
      } catch(CharacterCodingException e){
	  // XXX - Ignore coding exceptions? They shouldn't really happen.
	  return null;
      }	  
  }

  /**
   * Converts the Unicode characters in this String to a byte array. Uses the
   * encoding of the platform's default charset, so the result may be longer
   * or shorter than the String. For more encoding control, use
   * {@link java.nio.charset.CharsetEncoder}. Unsupported characters get
   * replaced by an encoding specific byte.
   *
   * @return the resulting byte array, or null on a problem
   * @since 1.1
   */
  public byte[] getBytes()
  { 
      try 
	  {
	      return getBytes(System.getProperty("file.encoding"));
	  } catch(Exception e) {
	      // XXX - Throw an error here? 
	      // For now, default to the 'safe' encoding.
	      byte[] bytes = new byte[count];
	      for(int i=0;i<count;i++)
		  bytes[i] = (byte)((value[offset+i] <= 0xFF)?
				    value[offset+i]:'?');
	      return bytes;
      }
  }

  /**
   * Predicate which compares anObject to this. This is true only for Strings
   * with the same character sequence.
   *
   * @param anObject the object to compare
   * @return true if anObject is semantically equal to this
   * @see #compareTo(String)
   * @see #equalsIgnoreCase(String)
   */
  public boolean equals(Object anObject)
  {
    if (! (anObject instanceof String))
      return false;
    String str2 = (String) anObject;
    if (count != str2.count)
      return false;
    if (value == str2.value && offset == str2.offset)
      return true;
    int i = count;
    int x = offset;
    int y = str2.offset;
    while (--i >= 0)
      if (value[x++] != str2.value[y++])
        return false;
    return true;
  }

  /**
   * Compares the given StringBuffer to this String. This is true if the
   * StringBuffer has the same content as this String at this moment.
   *
   * @param buffer the StringBuffer to compare to
   * @return true if StringBuffer has the same character sequence
   * @throws NullPointerException if the given StringBuffer is null
   * @since 1.4
   */
  public boolean contentEquals(StringBuffer buffer)
  {
    synchronized (buffer)
      {
        if (count != buffer.count)
          return false;
        if (value == buffer.value)
          return true; // Possible if shared.
        int i = count;
        int x = offset + count;
        while (--i >= 0)
          if (value[--x] != buffer.value[i])
            return false;
        return true;
      }
  }

  /**
   * Compares a String to this String, ignoring case. This does not handle
   * multi-character capitalization exceptions; instead the comparison is
   * made on a character-by-character basis, and is true if:<br><ul>
   * <li><code>c1 == c2</code></li>
   * <li><code>Character.toUpperCase(c1)
   *     == Character.toUpperCase(c2)</code></li>
   * <li><code>Character.toLowerCase(c1)
   *     == Character.toLowerCase(c2)</code></li>
   * </ul>
   *
   * @param anotherString String to compare to this String
   * @return true if anotherString is equal, ignoring case
   * @see #equals(Object)
   * @see Character#toUpperCase(char)
   * @see Character#toLowerCase(char)
   */
  public boolean equalsIgnoreCase(String anotherString)
  {
    if (anotherString == null || count != anotherString.count)
      return false;
    int i = count;
    int x = offset;
    int y = anotherString.offset;
    while (--i >= 0)
      {
        char c1 = value[x++];
        char c2 = anotherString.value[y++];
        // Note that checking c1 != c2 is redundant, but avoids method calls.
        if (c1 != c2
            && Character.toUpperCase(c1) != Character.toUpperCase(c2)
            && Character.toLowerCase(c1) != Character.toLowerCase(c2))
          return false;
      }
    return true;
  }

  /**
   * Compares this String and another String (case sensitive,
   * lexicographically). The result is less than 0 if this string sorts
   * before the other, 0 if they are equal, and greater than 0 otherwise.
   * After any common starting sequence is skipped, the result is
   * <code>this.charAt(k) - anotherString.charAt(k)</code> if both strings
   * have characters remaining, or
   * <code>this.length() - anotherString.length()</code> if one string is
   * a subsequence of the other.
   *
   * @param anotherString the String to compare against
   * @return the comparison
   * @throws NullPointerException if anotherString is null
   */
  public int compareTo(String anotherString)
  {
    int i = Math.min(count, anotherString.count);
    int x = offset;
    int y = anotherString.offset;
    while (--i >= 0)
      {
        int result = value[x++] - anotherString.value[y++];
        if (result != 0)
          return result;
      }
    return count - anotherString.count;
  }

  /**
   * Behaves like <code>compareTo(java.lang.String)</code> unless the Object
   * is not a <code>String</code>.  Then it throws a
   * <code>ClassCastException</code>.
   *
   * @param o the object to compare against
   * @return the comparison
   * @throws NullPointerException if o is null
   * @throws ClassCastException if o is not a <code>String</code>
   * @since 1.2
   */
  public int compareTo(Object o)
  {
    return compareTo((String) o);
  }

  /**
   * Compares this String and another String (case insensitive). This
   * comparison is <em>similar</em> to equalsIgnoreCase, in that it ignores
   * locale and multi-characater capitalization, and compares characters
   * after performing
   * <code>Character.toLowerCase(Character.toUpperCase(c))</code> on each
   * character of the string. This is unsatisfactory for locale-based
   * comparison, in which case you should use {@link java.text.Collator}.
   *
   * @param str the string to compare against
   * @return the comparison
   * @see Collator#compare(String, String)
   * @since 1.2
   */
  public int compareToIgnoreCase(String str)
  {
    int i = Math.min(count, str.count);
    int x = offset;
    int y = str.offset;
    while (--i >= 0)
      {
        int result = Character.toLowerCase(Character.toUpperCase(value[x++]))
          - Character.toLowerCase(Character.toUpperCase(str.value[y++]));
        if (result != 0)
          return result;
      }
    return count - str.count;
  }  

  /**
   * Predicate which determines if this String matches another String
   * starting at a specified offset for each String and continuing
   * for a specified length. Indices out of bounds are harmless, and give
   * a false result.
   *
   * @param toffset index to start comparison at for this String
   * @param other String to compare region to this String
   * @param ooffset index to start comparison at for other
   * @param len number of characters to compare
   * @return true if regions match (case sensitive)
   * @throws NullPointerException if other is null
   */
  public boolean regionMatches(int toffset, String other, int ooffset, int len)
  {
    return regionMatches(false, toffset, other, ooffset, len);
  }

  /**
   * Predicate which determines if this String matches another String
   * starting at a specified offset for each String and continuing
   * for a specified length, optionally ignoring case. Indices out of bounds
   * are harmless, and give a false result. Case comparisons are based on
   * <code>Character.toLowerCase()</code> and
   * <code>Character.toUpperCase()</code>, not on multi-character
   * capitalization expansions.
   *
   * @param ignoreCase true if case should be ignored in comparision
   * @param toffset index to start comparison at for this String
   * @param other String to compare region to this String
   * @param ooffset index to start comparison at for other
   * @param len number of characters to compare
   * @return true if regions match, false otherwise
   * @throws NullPointerException if other is null
   */
  public boolean regionMatches(boolean ignoreCase, int toffset,
                               String other, int ooffset, int len)
  {
    if (toffset < 0 || ooffset < 0 || toffset + len > count
        || ooffset + len > other.count)
      return false;
    toffset += offset;
    ooffset += other.offset;
    while (--len >= 0)
      {
        char c1 = value[toffset++];
        char c2 = other.value[ooffset++];
        // Note that checking c1 != c2 is redundant when ignoreCase is true,
        // but it avoids method calls.
        if (c1 != c2
            && (! ignoreCase
                || (Character.toLowerCase(c1) != Character.toLowerCase(c2)
                    && (Character.toUpperCase(c1)
                        != Character.toUpperCase(c2)))))
          return false;
      }
    return true;
  }

  /**
   * Predicate which determines if this String contains the given prefix,
   * beginning comparison at toffset. The result is false if toffset is
   * negative or greater than this.length(), otherwise it is the same as
   * <code>this.substring(toffset).startsWith(prefix)</code>.
   *
   * @param prefix String to compare
   * @param toffset offset for this String where comparison starts
   * @return true if this String starts with prefix
   * @throws NullPointerException if prefix is null
   * @see #regionMatches(boolean, int, String, int, int)
   */
  public boolean startsWith(String prefix, int toffset)
  {
    return regionMatches(false, toffset, prefix, 0, prefix.count);
  }

  /**
   * Predicate which determines if this String starts with a given prefix.
   * If the prefix is an empty String, true is returned.
   *
   * @param prefix String to compare
   * @return true if this String starts with the prefix
