/*
 *******************************************************************************
 * Copyright (C) 1996-2000, International Business Machines Corporation and    *
 * others. All Rights Reserved.                                                *
 *******************************************************************************
 *
 * $Source: /usr/cvs/icu4j/icu4j/src/com/ibm/icu/impl/ICUCharacterIterator.java,v $ 
 * $Date: 2002/06/20 01:18:07 $ 
 * $Revision: 1.1 $
 *
 *******************************************************************************
 */
 
package com.ibm.icu.impl;

import java.text.CharacterIterator;

/**
 * This class is a wrapper around UCharacterIterator and implements the 
 * CharacterIterator protocol
 * @author ram
 */
public class UCharacterIteratorWrapper implements CharacterIterator{
    
    public UCharacterIteratorWrapper(UCharacterIterator iter){
        this.iterator = iter;
        this.currentIndex = 0;
        this.length = iter.getLength();
        //UCharacterIterator always iterates from 0 - length
        this.beginIndex = 0;
    }
    
    private UCharacterIterator iterator;
    private int currentIndex;
    private int length;
    private int beginIndex;

    /**
     * Sets the position to getBeginIndex() and returns the character at that
     * position.
     * @return the first character in the text, or DONE if the text is empty
     * @see #getBeginIndex()
     */
    public char first(){
        iterator.setIndex(beginIndex);
        return (char)iterator.current();
    }

    /**
     * Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty)
     * and returns the character at that position.
     * @return the last character in the text, or DONE if the text is empty
     * @see #getEndIndex()
     */
    public char last(){
        iterator.setIndex(length-1);
        return (char)iterator.current();
    }

    /**
     * Gets the character at the current position (as returned by getIndex()).
     * @return the character at the current position or DONE if the current
     * position is off the end of the text.
     * @see #getIndex()
     */
    public char current(){
        iterator.setIndex(currentIndex);
        return (char) iterator.current();
    }

    /**
     * Increments the iterator's index by one and returns the character
     * at the new index.  If the resulting index is greater or equal
     * to getEndIndex(), the current index is reset to getEndIndex() and
     * a value of DONE is returned.
     * @return the character at the new position or DONE if the new
     * position is off the end of the text range.
     */
    public char next(){
        //pre-increment
        iterator.setIndex(++currentIndex);
        return (char) iterator.current();
    }

    /**
     * Decrements the iterator's index by one and returns the character
     * at the new index. If the current index is getBeginIndex(), the index
     * remains at getBeginIndex() and a value of DONE is returned.
     * @return the character at the new position or DONE if the current
     * position is equal to getBeginIndex().
     */
    public char previous(){
        //pre-decrement
        iterator.setIndex(--currentIndex);
        return (char) iterator.current();
    }

    /**
     * Sets the position to the specified position in the text and returns that
     * character.
     * @param position the position within the text.  Valid values range from
     * getBeginIndex() to getEndIndex().  An IllegalArgumentException is thrown
     * if an invalid value is supplied.
     * @return the character at the specified position or DONE if the specified position is equal to getEndIndex()
     */
    public char setIndex(int position){
        currentIndex=position;
        return (char) iterator.current();
    }

    /**
     * Returns the start index of the text.
     * @return the index at which the text begins.
     */
    public int getBeginIndex(){
        return beginIndex;
    }

    /**
     * Returns the end index of the text.  This index is the index of the first
     * character following the end of the text.
     * @return the index after the last character in the text
     */
    public int getEndIndex(){
        return length;
    }

    /**
     * Returns the current index.
     * @return the current index.
     */
    public int getIndex(){
        return currentIndex;
    }

    /**
     * Create a copy of this iterator
     * @return A copy of this
     */
    public Object clone(){
        try {
            UCharacterIteratorWrapper result = (UCharacterIteratorWrapper) super.clone();
            result.iterator = (UCharacterIterator)this.iterator.clone();
            return result;
        } catch (CloneNotSupportedException e) {      
            return null; // only invoked if bad underlying character iterator
        }
    }   

}