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  * 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

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  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

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 package java.util;

 import java.lang.*;

 /**

  * The string tokenizer class allows an application to break a

  * string into tokens. The tokenization method is much simpler than

  * the one used by the <code>StreamTokenizer</code> class. The

  * <code>StringTokenizer</code> methods do not distinguish among

  * identifiers, numbers, and quoted strings, nor do they recognize

  * and skip comments.

  * <p>

  * The set of delimiters (the characters that separate tokens) may

  * be specified either at creation time or on a per-token basis.

  * <p>

  * An instance of <code>StringTokenizer</code> behaves in one of two

  * ways, depending on whether it was created with the

  * <code>returnDelims</code> flag having the value <code>true</code>

  * or <code>false</code>:

  * <ul>

  * <li>If the flag is <code>false</code>, delimiter characters serve to

  *     separate tokens. A token is a maximal sequence of consecutive

  *     characters that are not delimiters.

  * <li>If the flag is <code>true</code>, delimiter characters are themselves

  *     considered to be tokens. A token is thus either one delimiter

  *     character, or a maximal sequence of consecutive characters that are

  *     not delimiters.

  * </ul><p>

  * A <tt>StringTokenizer</tt> object internally maintains a current

  * position within the string to be tokenized. Some operations advance this

  * current position past the characters processed.<p>

  * A token is returned by taking a substring of the string that was used to

  * create the <tt>StringTokenizer</tt> object.

  * <p>

  * The following is one example of the use of the tokenizer. The code:

  * <blockquote><pre>

  *     StringTokenizer st = new StringTokenizer("this is a test");

  *     while (st.hasMoreTokens()) {

  *         System.out.println(st.nextToken());

  *     }

  * </pre></blockquote>

  * <p>

  * prints the following output:

  * <blockquote><pre>

  *     this

  *     is

  *     a

  *     test

  * </pre></blockquote>

  *

  * <p>

  * <tt>StringTokenizer</tt> is a legacy class that is retained for

  * compatibility reasons although its use is discouraged in new code. It is

  * recommended that anyone seeking this functionality use the <tt>split</tt>

  * method of <tt>String</tt> or the java.util.regex package instead.

  * <p>

  * The following example illustrates how the <tt>String.split</tt>

  * method can be used to break up a string into its basic tokens:

  * <blockquote><pre>

  *     String[] result = "this is a test".split("\\s");

  *     for (int x=0; x<result.length; x++)

  *         System.out.println(result[x]);

  * </pre></blockquote>

  * <p>

  * prints the following output:

  * <blockquote><pre>

  *     this

  *     is

  *     a

  *     test

  * </pre></blockquote>

  *

  * @author  unascribed

  * @see     java.io.StreamTokenizer

  * @since   JDK1.0

  */

 public

 class StringTokenizer implements Enumeration<Object> {

     private int currentPosition;

     private int newPosition;

     private int maxPosition;

     private String str;

     private String delimiters;

     private boolean retDelims;

     private boolean delimsChanged;

     /**

      * maxDelimCodePoint stores the value of the delimiter character with the

      * highest value. It is used to optimize the detection of delimiter

      * characters.

      *

      * It is unlikely to provide any optimization benefit in the

      * hasSurrogates case because most string characters will be

      * smaller than the limit, but we keep it so that the two code

      * paths remain similar.

      */

     private int maxDelimCodePoint;

     /**

      * If delimiters include any surrogates (including surrogate

      * pairs), hasSurrogates is true and the tokenizer uses the

      * different code path. This is because String.indexOf(int)

      * doesn't handle unpaired surrogates as a single character.

      */

     private boolean hasSurrogates = false;

     /**

      * When hasSurrogates is true, delimiters are converted to code

      * points and isDelimiter(int) is used to determine if the given

      * codepoint is a delimiter.

      */

     private int[] delimiterCodePoints;

     /**

      * Set maxDelimCodePoint to the highest char in the delimiter set.

      */

     private void setMaxDelimCodePoint() {

         if (delimiters == null) {

             maxDelimCodePoint = 0;

             return;

         }

         int m = 0;

         int c;

         int count = 0;

         for (int i = 0; i < delimiters.length(); i += Character.charCount(c)) {

             c = delimiters.charAt(i);

             if (c >= Character.MIN_HIGH_SURROGATE && c <= Character.MAX_LOW_SURROGATE) {

                 c = delimiters.codePointAt(i);

                 hasSurrogates = true;

             }

             if (m < c)

                 m = c;

             count++;

         }

         maxDelimCodePoint = m;

         if (hasSurrogates) {

             delimiterCodePoints = new int[count];

             for (int i = 0, j = 0; i < count; i++, j += Character.charCount(c)) {

                 c = delimiters.codePointAt(j);

                 delimiterCodePoints[i] = c;

             }

         }

     }

     /**

      * Constructs a string tokenizer for the specified string. All

      * characters in the <code>delim</code> argument are the delimiters

      * for separating tokens.

      * <p>

      * If the <code>returnDelims</code> flag is <code>true</code>, then

      * the delimiter characters are also returned as tokens. Each

      * delimiter is returned as a string of length one. If the flag is

      * <code>false</code>, the delimiter characters are skipped and only

      * serve as separators between tokens.

      * <p>

      * Note that if <tt>delim</tt> is <tt>null</tt>, this constructor does

      * not throw an exception. However, trying to invoke other methods on the

      * resulting <tt>StringTokenizer</tt> may result in a

      * <tt>NullPointerException</tt>.

      *

      * @param   str            a string to be parsed.

      * @param   delim          the delimiters.

      * @param   returnDelims   flag indicating whether to return the delimiters

      *                         as tokens.

      * @exception NullPointerException if str is <CODE>null</CODE>

      */

     public StringTokenizer(String str, String delim, boolean returnDelims) {

         currentPosition = 0;

         newPosition = -1;

         delimsChanged = false;

         this.str = str;

         maxPosition = str.length();

         delimiters = delim;

         retDelims = returnDelims;

         setMaxDelimCodePoint();

     }

     /**

      * Constructs a string tokenizer for the specified string. The

      * characters in the <code>delim</code> argument are the delimiters

      * for separating tokens. Delimiter characters themselves will not

      * be treated as tokens.

      * <p>

      * Note that if <tt>delim</tt> is <tt>null</tt>, this constructor does

      * not throw an exception. However, trying to invoke other methods on the

      * resulting <tt>StringTokenizer</tt> may result in a

      * <tt>NullPointerException</tt>.

      *

      * @param   str     a string to be parsed.

      * @param   delim   the delimiters.

      * @exception NullPointerException if str is <CODE>null</CODE>

      */

     public StringTokenizer(String str, String delim) {

         this(str, delim, false);

     }

     /**

      * Constructs a string tokenizer for the specified string. The

      * tokenizer uses the default delimiter set, which is

      * <code>"&nbsp;&#92;t&#92;n&#92;r&#92;f"</code>: the space character,

      * the tab character, the newline character, the carriage-return character,

      * and the form-feed character. Delimiter characters themselves will

      * not be treated as tokens.

      *

      * @param   str   a string to be parsed.

      * @exception NullPointerException if str is <CODE>null</CODE>

      */

     public StringTokenizer(String str) {

         this(str, " \t\n\r\f", false);

     }

     /**

      * Skips delimiters starting from the specified position. If retDelims

      * is false, returns the index of the first non-delimiter character at or

      * after startPos. If retDelims is true, startPos is returned.

      */

     private int skipDelimiters(int startPos) {

         if (delimiters == null)

             throw new NullPointerException();

         int position = startPos;

         while (!retDelims && position < maxPosition) {

             if (!hasSurrogates) {

                 char c = str.charAt(position);

                 if ((c > maxDelimCodePoint) || (delimiters.indexOf(c) < 0))

                     break;

                 position++;

             } else {

                 int c = str.codePointAt(position);

                 if ((c > maxDelimCodePoint) || !isDelimiter(c)) {

                     break;

                 }

                 position += Character.charCount(c);

             }

         }

         return position;

     }

     /**

      * Skips ahead from startPos and returns the index of the next delimiter

      * character encountered, or maxPosition if no such delimiter is found.

      */

     private int scanToken(int startPos) {

         int position = startPos;

         while (position < maxPosition) {

             if (!hasSurrogates) {

                 char c = str.charAt(position);

                 if ((c <= maxDelimCodePoint) && (delimiters.indexOf(c) >= 0))

                     break;

                 position++;

             } else {

                 int c = str.codePointAt(position);

                 if ((c <= maxDelimCodePoint) && isDelimiter(c))

                     break;

                 position += Character.charCount(c);

             }

         }

         if (retDelims && (startPos == position)) {

             if (!hasSurrogates) {

                 char c = str.charAt(position);

                 if ((c <= maxDelimCodePoint) && (delimiters.indexOf(c) >= 0))

                     position++;

             } else {

                 int c = str.codePointAt(position);

                 if ((c <= maxDelimCodePoint) && isDelimiter(c))

                     position += Character.charCount(c);

             }

         }

         return position;

     }

     private boolean isDelimiter(int codePoint) {

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

             if (delimiterCodePoints[i] == codePoint) {

                 return true;

             }

         }

         return false;

     }

     /**

      * Tests if there are more tokens available from this tokenizer's string.

      * If this method returns <tt>true</tt>, then a subsequent call to

      * <tt>nextToken</tt> with no argument will successfully return a token.

      *

      * @return  <code>true</code> if and only if there is at least one token

      *          in the string after the current position; <code>false</code>

      *          otherwise.

      */

     public boolean hasMoreTokens() {

         /*

          * Temporarily store this position and use it in the following

          * nextToken() method only if the delimiters haven't been changed in

          * that nextToken() invocation.

          */

         newPosition = skipDelimiters(currentPosition);

         return (newPosition < maxPosition);

     }

     /**

      * Returns the next token from this string tokenizer.

      *

      * @return     the next token from this string tokenizer.

      * @exception  NoSuchElementException  if there are no more tokens in this

      *               tokenizer's string.

      */

     public String nextToken() {

         /*

          * If next position already computed in hasMoreElements() and

          * delimiters have changed between the computation and this invocation,

          * then use the computed value.

          */

         currentPosition = (newPosition >= 0 && !delimsChanged) ?

             newPosition : skipDelimiters(currentPosition);

         /* Reset these anyway */

         delimsChanged = false;

         newPosition = -1;

         if (currentPosition >= maxPosition)

             throw new NoSuchElementException();

         int start = currentPosition;

         currentPosition = scanToken(currentPosition);

         return str.substring(start, currentPosition);

     }

     /**

      * Returns the next token in this string tokenizer's string. First,

      * the set of characters considered to be delimiters by this

      * <tt>StringTokenizer</tt> object is changed to be the characters in

      * the string <tt>delim</tt>. Then the next token in the string

      * after the current position is returned. The current position is

      * advanced beyond the recognized token.  The new delimiter set

      * remains the default after this call.

      *

      * @param      delim   the new delimiters.

      * @return     the next token, after switching to the new delimiter set.

      * @exception  NoSuchElementException  if there are no more tokens in this

      *               tokenizer's string.

      * @exception NullPointerException if delim is <CODE>null</CODE>

      */

     public String nextToken(String delim) {

         delimiters = delim;

         /* delimiter string specified, so set the appropriate flag. */

         delimsChanged = true;

         setMaxDelimCodePoint();

         return nextToken();

     }

     /**

      * Returns the same value as the <code>hasMoreTokens</code>

      * method. It exists so that this class can implement the

      * <code>Enumeration</code> interface.

      *

      * @return  <code>true</code> if there are more tokens;

      *          <code>false</code> otherwise.

      * @see     java.util.Enumeration

      * @see     java.util.StringTokenizer#hasMoreTokens()

      */

     public boolean hasMoreElements() {

         return hasMoreTokens();

     }

     /**

      * Returns the same value as the <code>nextToken</code> method,

      * except that its declared return value is <code>Object</code> rather than

      * <code>String</code>. It exists so that this class can implement the

      * <code>Enumeration</code> interface.

      *

      * @return     the next token in the string.

      * @exception  NoSuchElementException  if there are no more tokens in this

      *               tokenizer's string.

      * @see        java.util.Enumeration

      * @see        java.util.StringTokenizer#nextToken()

      */

     public Object nextElement() {

         return nextToken();

     }

     /**

      * Calculates the number of times that this tokenizer's

      * <code>nextToken</code> method can be called before it generates an

      * exception. The current position is not advanced.

      *

      * @return  the number of tokens remaining in the string using the current

      *          delimiter set.

      * @see     java.util.StringTokenizer#nextToken()

      */

     public int countTokens() {

         int count = 0;

         int currpos = currentPosition;

         while (currpos < maxPosition) {

             currpos = skipDelimiters(currpos);

             if (currpos >= maxPosition)

                 break;

             currpos = scanToken(currpos);

             count++;

         }

         return count;

     }

 }