GCOptimizedCharIndex.java

/**
 * Copyright (c) 2003-2009, Xith3D Project Group all rights reserved.
 * 
 * Portions based on the Java3D interface, Copyright by Sun Microsystems.
 * Many thanks to the developers of Java3D and Sun Microsystems for their
 * innovation and design.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the 'Xith3D Project Group' nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) A
 * RISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE
 */
package org.xith3d.utility.characters;

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;

/**
 * Provides methods to get information about printable characters.
 * Any printable character is assotiated with an index to be used in an array
 * of the size [total number of printable chars].
 * 
 * This CharIndex caches the printables in a big int array and does everything in O(1).
 * 
 * @author Kevin Finley (aka horati)
 * @author Marvin Froehlich (aka Qudus)
 */
class GCOptimizedCharIndex extends CharIndex
{
    private Charset charset;
    private int[] arrayCache;
    
    private int numPrintables = -1;
    
    /**
     * {@inheritDoc}
     */
    @Override
    public final MemoryStrategy getMemoryStrategy()
    {
        return ( MemoryStrategy.GC_OPTIMIZED  );
    }
    
    /**
     * {@inheritDoc}
     */
    @Override
    public Charset getCharset()
    {
        return ( charset );
    }
    
    /**
     * {@inheritDoc}
     */
    @Override
    public int getTotalNumberOfCharacters()
    {
        return ( Short.MAX_VALUE + 1 );
    }
    
    /**
     * {@inheritDoc}
     */
    @Override
    public int getNumberOfPrintableChars()
    {
        return ( numPrintables );
    }
    
    /**
     * {@inheritDoc}
     */
    @Override
    public int getIndex( char ch )
    {
        return ( arrayCache[ ch ] );
    }
    
    /**
     * Computes and returns an array of "pointers".<br>
     * Any printable char's index will carry an int greater or equal to zero.
     * This way you can use this array to point to the elements of another
     * (smaller) array containing assotiated info for each printable char.<br>
     * <br>
     * This method simply calls getPrintableChars( Charset.forName( charset ) ).
     * 
     * @param charset the charset to use
     * 
     * @return the map-array
     */
    private int[] createArrayCache( Charset charset )
    {
        final int n = getTotalNumberOfCharacters();
        final int[] result = new int[ n ];
        final CharBuffer charBuffer = CharBuffer.allocate( 1 );
        final ByteBuffer byteBuffer = ByteBuffer.allocate( 2 );
        final CharsetEncoder encoder = charset.newEncoder();
        
        numPrintables = 0;
        for ( char ch = 0; ch < n; ch++ )
        {
            if ( isPrintable( ch, encoder, charBuffer, byteBuffer ) )
            {
                result[ ch ] = numPrintables++;
            }
            else
            {
                result[ ch ] = -1;
            }
            
            charBuffer.clear();
            byteBuffer.clear();
        }
        
        return ( result );
    }
    
    public GCOptimizedCharIndex( Charset charset )
    {
        super();
        
        this.charset = charset;
        this.arrayCache = createArrayCache( charset );
    }
}