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/*
 *******************************************************************************
 * Copyright (C) 1996-2014, International Business Machines Corporation and    *
 * others. All Rights Reserved.                                                *
 *******************************************************************************
 */

package jdk.internal.icu.text;

import jdk.internal.icu.impl.CharacterIteratorWrapper;
import jdk.internal.icu.impl.ReplaceableUCharacterIterator;
import jdk.internal.icu.impl.UCharacterProperty;

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
java.text.CharacterIterator 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, java.text.CharacterIterator can only iterate over
code units and is limited to BMP (0 - 0xFFFF)

Author:Ram
@stableICU 2.4
/**
 * 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

@stableICU 2.4
/**
     * 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

@stableICU 2.4
/**
     * 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 UCharacterIterator object given a
source string.

Params:
  • source – a string
Throws:
Returns:UCharacterIterator object
@stableICU 2.4
/**
     * 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 UCharacterIterator object given a
source StringBuffer.

Params:
  • source – an string buffer of UTF-16 code units
Throws:
Returns:UCharacterIterator object
@stableICU 2.4
/**
     * 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 UCharacterIterator object given a
CharacterIterator.

Params:
  • source – a valid CharacterIterator object.
Throws:
Returns:UCharacterIterator object
@stableICU 2.4
/**
     * 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

Returns:length of the text
@stableICU 2.4
/**
     * 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.

Returns:current index in text.
@stableICU 2.4
/**
     * 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.

Returns:the next UTF16 code unit, or DONE if the index is at the limit
        of the text.
@stableICU 2.4
/**
     * 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
next().  Otherwise the iterator is incremented past
the surrogate pair, and the code point represented by the pair
is returned.

Returns:the next codepoint in text, or DONE if the index is at
        the limit of the text.
@stableICU 2.4
/**
     * 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.

Returns:the previous code unit in the text, or DONE if the new
        index is before the start of the text.
@stableICU 2.4
/**
     * 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();


    
Retreat to the start of the previous code point in the text,
and return it (pre-decrement semantics).  If the index is not
preceeded by a valid surrogate pair, the behavior is the same
as previous().  Otherwise the iterator is
decremented to the start of the surrogate pair, and the code
point represented by the pair is returned.

Returns:the previous code point in the text, or DONE if the new
        index is before the start of the text.
@stableICU 2.4
/**
     * Retreat to the start of the previous code point in the text,
     * and return it (pre-decrement semantics).  If the index is not
     * preceeded by a valid surrogate pair, the behavior is the same
     * as <code>previous()</code>.  Otherwise the iterator is
     * decremented to the start of the surrogate pair, and the code
     * point represented by the pair is returned.
     * @return the previous code point in the text, or DONE if the new
     *         index is before the start of the text.
     * @stable ICU 2.4
     */
    public int previousCodePoint(){
        int ch1 = previous();
        if(UTF16.isTrailSurrogate((char)ch1)){
            int ch2 = previous();
            if(UTF16.isLeadSurrogate((char)ch2)){
                return UCharacterProperty.getRawSupplementary((char)ch2,
                                                              (char)ch1);
            }else if (ch2 != DONE) {
                //unmatched trail surrogate so back out
                next();
            }
        }
        return ch1;
    }

    
Sets the index to the specified index in the text.

Params:
  • index – the index within the text.
Throws:
@stableICU 2.4
/**
     * 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);

    
Sets the current index to the start.

@stableICU 2.4
/**
     * Sets the current index to the start.
     * @stable ICU 2.4
     */
    public void setToStart() {
        setIndex(0);
    }

    
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 getLength().
Usage:


        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()];
            }
        }



Params:
  • fillIn – an array of chars to fill with the underlying UTF-16 code
        units.
  • offset – the position within the array to start putting the data.
Throws:
Returns:the number of code units added to fillIn, as a convenience
@stableICU 2.4
/**
     * 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
     * @exception IndexOutOfBoundsException exception if there is not enough
     *            room after offset in the array, or if offset < 0.
     * @stable ICU 2.4
     */
    public abstract int getText(char[] fillIn, int offset);

    
Convenience override for getText(char[], int) that provides
an offset of 0.

Params:
  • fillIn – an array of chars to fill with the underlying UTF-16 code
        units.
Throws:
Returns:the number of code units added to fillIn, as a convenience
@stableICU 2.4
/**
     * 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
     * @exception IndexOutOfBoundsException exception if there is not enough
     *            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

Returns:the underlying text storage in the iterator as a string
@stableICU 2.4
/**
     * 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);
    }

    
Moves the current position by the number of code points
specified, either forward or backward depending on the sign of
delta (positive or negative respectively). If the current index
is at a trail surrogate then the first adjustment is by code
unit, and the remaining adjustments are by code points.  If the
resulting index would be less than zero, the index is set to
zero, and if the resulting index would be greater than limit,
the index is set to limit.

Params:
  • delta – the number of code units to move the current index.
Throws:
Returns:the new index
@stableICU 2.4
/**
     * Moves the current position by the number of code points
     * specified, either forward or backward depending on the sign of
     * delta (positive or negative respectively). If the current index
     * is at a trail surrogate then the first adjustment is by code
     * unit, and the remaining adjustments are by code points.  If the
     * resulting index would be less than zero, the index is set to
     * zero, and if the resulting index would be greater than limit,
     * the index is set to limit.
     * @param delta the number of code units to move the current index.
     * @return the new index
     * @exception IndexOutOfBoundsException is thrown if an invalid delta is
     *            supplied
     * @stable ICU 2.4
     *
     */
    public int moveCodePointIndex(int delta){
        if(delta>0){
            while(delta>0 && nextCodePoint() != DONE){delta--;}
        }else{
            while(delta<0 && previousCodePoint() != DONE){delta++;}
        }
        if(delta!=0){
            throw new IndexOutOfBoundsException();
        }

        return getIndex();
    }

    
Creates a copy of this iterator, independent from other iterators.
If it is not possible to clone the iterator, returns null.

Returns:copy of this iterator
@stableICU 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();
    }

}