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/*

 *******************************************************************************

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 */

package sun.text.normalizer;

import java.text.CharacterIterator;

/**

 * Abstract class that defines an API for iteration on text objects.This is an

 * interface for forward and backward iteration and random access into a text

 * object. Forward iteration is done with post-increment and backward iteration

 * is done with pre-decrement semantics, while the

 * <code>java.text.CharacterIterator</code> interface methods provided forward

 * iteration with "pre-increment" and backward iteration with pre-decrement

 * semantics. This API is more efficient for forward iteration over code points.

 * The other major difference is that this API can do both code unit and code point

 * iteration, <code>java.text.CharacterIterator</code> can only iterate over

 * code units and is limited to BMP (0 - 0xFFFF)

 * @author Ram

 * @stable ICU 2.4

 */

public abstract class UCharacterIterator

                      implements Cloneable {

    /**

     * Protected default constructor for the subclasses

     * @stable ICU 2.4

     */

    protected UCharacterIterator(){

    }

    /**

     * Indicator that we have reached the ends of the UTF16 text.

     * Moved from UForwardCharacterIterator.java

     * @stable ICU 2.4

     */

    public static final int DONE = -1;

    // static final methods ----------------------------------------------------

    /**

     * Returns a <code>UCharacterIterator</code> object given a

     * source string.

     * @param source a string

     * @return UCharacterIterator object

     * @exception IllegalArgumentException if the argument is null

     * @stable ICU 2.4

     */

    public static final UCharacterIterator getInstance(String source){

        return new ReplaceableUCharacterIterator(source);

    }

    /**

     * Returns a <code>UCharacterIterator</code> object given a

     * source StringBuffer.

     * @param source an string buffer of UTF-16 code units

     * @return UCharacterIterator object

     * @exception IllegalArgumentException if the argument is null

     * @stable ICU 2.4

     */

    public static final UCharacterIterator getInstance(StringBuffer source){

        return new ReplaceableUCharacterIterator(source);

    }

     * Returns a <code>UCharacterIterator</code> object given a

     * CharacterIterator.

     * @param source a valid CharacterIterator object.

     * @return UCharacterIterator object

     * @exception IllegalArgumentException if the argument is null

     * @stable ICU 2.4

     */

    public static final UCharacterIterator getInstance(CharacterIterator source){

        return new CharacterIteratorWrapper(source);

    }

    // public methods ----------------------------------------------------------

    /**

     * Returns the length of the text

     * @return length of the text

     * @stable ICU 2.4

     */

    public abstract int getLength();

    /**

     * Gets the current index in text.

     * @return current index in text.

     * @stable ICU 2.4

     */

    public abstract int getIndex();

    /**

     * Returns the UTF16 code unit at index, and increments to the next

     * code unit (post-increment semantics).  If index is out of

     * range, DONE is returned, and the iterator is reset to the limit

     * of the text.

     * @return the next UTF16 code unit, or DONE if the index is at the limit

     *         of the text.

     * @stable ICU 2.4

     */

    public abstract int next();

    /**

     * Returns the code point at index, and increments to the next code

     * point (post-increment semantics).  If index does not point to a

     * valid surrogate pair, the behavior is the same as

     * <code>next()</code>.  Otherwise the iterator is incremented past

     * the surrogate pair, and the code point represented by the pair

     * is returned.

     * @return the next codepoint in text, or DONE if the index is at

     *         the limit of the text.

     * @stable ICU 2.4

     */

    public int nextCodePoint(){

        int ch1 = next();

        if(UTF16.isLeadSurrogate((char)ch1)){

            int ch2 = next();

            if(UTF16.isTrailSurrogate((char)ch2)){

                return UCharacterProperty.getRawSupplementary((char)ch1,

                                                              (char)ch2);

            }else if (ch2 != DONE) {

                // unmatched surrogate so back out

                previous();

            }

        }

        return ch1;

    }

    /**

     * Decrement to the position of the previous code unit in the

     * text, and return it (pre-decrement semantics).  If the

     * resulting index is less than 0, the index is reset to 0 and

     * DONE is returned.

     * @return the previous code unit in the text, or DONE if the new

     *         index is before the start of the text.

     * @stable ICU 2.4

     */

    public abstract int previous();

    /**

     * Sets the index to the specified index in the text.

     * @param index the index within the text.

     * @exception IndexOutOfBoundsException is thrown if an invalid index is

     *            supplied

     * @stable ICU 2.4

     */

    public abstract void setIndex(int index);

    /**

     * Fills the buffer with the underlying text storage of the iterator

     * If the buffer capacity is not enough a exception is thrown. The capacity

     * of the fill in buffer should at least be equal to length of text in the

     * iterator obtained by calling <code>getLength()</code>.

     * <b>Usage:</b>

     *

     * <pre>{@code

     *         UChacterIterator iter = new UCharacterIterator.getInstance(text);

     *         char[] buf = new char[iter.getLength()];

     *         iter.getText(buf);

     *

     *         OR

     *         char[] buf= new char[1];

     *         int len = 0;

     *         for(;;){

     *             try{

     *                 len = iter.getText(buf);

     *                 break;

     *             }catch(IndexOutOfBoundsException e){

     *                 buf = new char[iter.getLength()];

     *             }

     *         }

     * }</pre>

     *

     * @param fillIn an array of chars to fill with the underlying UTF-16 code

     *         units.

     * @param offset the position within the array to start putting the data.

     * @return the number of code units added to fillIn, as a convenience

     * @stable ICU 2.4

     */

    public abstract int getText(char[] fillIn, int offset);

    /**

     * Convenience override for <code>getText(char[], int)</code> that provides

     * an offset of 0.

     * @param fillIn an array of chars to fill with the underlying UTF-16 code

     *         units.

     * @return the number of code units added to fillIn, as a convenience

     *            room in the array.

     * @stable ICU 2.4

     */

    public final int getText(char[] fillIn) {

        return getText(fillIn, 0);

    }

    /**

     * Convenience method for returning the underlying text storage as a string

     * @return the underlying text storage in the iterator as a string

     * @stable ICU 2.4

     */

    public String getText() {

        char[] text = new char[getLength()];

        getText(text);

        return new String(text);

    }

    /**

     *            supplied

     * @stable ICU 2.4

     *

     */

    }

    /**

     * Creates a copy of this iterator, independent from other iterators.

     * If it is not possible to clone the iterator, returns null.

     * @return copy of this iterator

     * @stable ICU 2.4

     */

    public Object clone() throws CloneNotSupportedException{

        return super.clone();

    }

}