/*
 
* Copyright (c) 1994, 2004, 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.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&lt;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
   
returnDelimsflag 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
   
stra string to be parsed.
     
* @param
   
delimthe 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
   
stra 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.
     
*
     
* @returnthe next token from this string tokenizer.
     
* @exception
  
NoSuchElementExceptionif 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.
     
* @returnthe next token, after switching to the new delimiter set.
     
* @exception
  
NoSuchElementExceptionif 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.
     
* @seejava.util.Enumeration
     
* @seejava.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.
     
*
     
* @returnthe next token in the string.
     
* @exception
  
NoSuchElementExceptionif 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.
     
* @seejava.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;
    
}
}