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International Component for Unicode for Java (ICU4J) is a mature, widely used Java library
providing Unicode and Globalization support
/*
*******************************************************************************
* Copyright (C) 1996-2009, International Business Machines Corporation and *
* others. All Rights Reserved. *
*******************************************************************************
*/
package com.ibm.icu.text;
import java.text.CharacterIterator;
import com.ibm.icu.impl.CharacterIteratorWrapper;
import com.ibm.icu.impl.ReplaceableUCharacterIterator;
import com.ibm.icu.impl.UCharArrayIterator;
import com.ibm.icu.impl.UCharacterIteratorWrapper;
import com.ibm.icu.impl.UCharacterProperty;
/**
* 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
* @stable ICU 2.4
*/
public abstract class UCharacterIterator
implements Cloneable,UForwardCharacterIterator {
/**
* Protected default constructor for the subclasses
* @stable ICU 2.4
*/
protected UCharacterIterator(){
}
// static final methods ----------------------------------------------------
/**
* Returns a UCharacterIterator object given a
* Replaceable object.
* @param source a valid source as a Replaceable object
* @return UCharacterIterator object
* @exception IllegalArgumentException if the argument is null
* @stable ICU 2.4
*/
public static final UCharacterIterator getInstance(Replaceable source){
return new ReplaceableUCharacterIterator(source);
}
/**
* Returns a UCharacterIterator 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 character array.
* @param source an array of UTF-16 code units
* @return UCharacterIterator object
* @exception IllegalArgumentException if the argument is null
* @stable ICU 2.4
*/
public static final UCharacterIterator getInstance(char[] source){
return getInstance(source,0,source.length);
}
/**
* Returns a UCharacterIterator object given a
* source character array.
* @param source an array of UTF-16 code units
* @return UCharacterIterator object
* @exception IllegalArgumentException if the argument is null
* @stable ICU 2.4
*/
public static final UCharacterIterator getInstance(char[] source, int start, int limit){
return new UCharArrayIterator(source,start,limit);
}
/**
* Returns a UCharacterIterator 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.
* @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 a java.text.CharacterIterator object for
* the underlying text of this iterator. The returned iterator is
* independent of this iterator.
* @return java.text.CharacterIterator object
* @stable ICU 2.4
*/
public CharacterIterator getCharacterIterator(){
return new UCharacterIteratorWrapper(this);
}
/**
* Returns the code unit at the current index. If index is out
* of range, returns DONE. Index is not changed.
* @return current code unit
* @stable ICU 2.4
*/
public abstract int current();
/**
* Returns the codepoint at the current index.
* If the current index is invalid, DONE is returned.
* If the current index points to a lead surrogate, and there is a following
* trail surrogate, then the code point is returned. Otherwise, the code
* unit at index is returned. Index is not changed.
* @return current codepoint
* @stable ICU 2.4
*/
public int currentCodePoint(){
int ch = current();
if(UTF16.isLeadSurrogate((char)ch)){
// advance the index to get the
// next code point
next();
// due to post increment semantics
// current() after next() actually
// returns the char we want
int ch2 = current();
// current should never change
// the current index so back off
previous();
if(UTF16.isTrailSurrogate((char)ch2)){
// we found a surrogate pair
// return the codepoint
return UCharacterProperty.getRawSupplementary(
(char)ch,(char)ch2
);
}
}
return ch;
}
/**
* 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
* next(). 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();
/**
* 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.
* @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.
* @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 limit.
* @stable ICU 2.4
*/
public void setToLimit() {
setIndex(getLength());
}
/**
* 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()];
* }
* }
*
*
*
* @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)>/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 as 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 units
* specified, either forward or backward depending on the sign
* of delta (positive or negative respectively). 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 index is
* supplied
* @stable ICU 2.4
*
*/
public int moveIndex(int delta) {
int x = Math.max(0, Math.min(getIndex() + delta, getLength()));
setIndex(x);
return x;
}
/**
* 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.
* @return copy of this iterator
* @stable ICU 2.4
*/
public Object clone() throws CloneNotSupportedException{
return super.clone();
}
}