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	/*
	* Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	/*
	* (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
	* (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved
	*
	* The original version of this source code and documentation
	* is copyrighted and owned by Taligent, Inc., a wholly-owned
	* subsidiary of IBM. These materials are provided under terms
	* of a License Agreement between Taligent and Sun. This technology
	* is protected by multiple US and International patents.
	*
	* This notice and attribution to Taligent may not be removed.
	* Taligent is a registered trademark of Taligent, Inc.
	*
	*/

	package java.text;

	import java.lang.ref.SoftReference;
	import java.text.spi.BreakIteratorProvider;
	import java.util.Locale;
	import sun.util.locale.provider.LocaleProviderAdapter;
	import sun.util.locale.provider.LocaleServiceProviderPool;


	/**
	* The <code>BreakIterator</code> class implements methods for finding
	* the location of boundaries in text. Instances of <code>BreakIterator</code>
	* maintain a current position and scan over text
	* returning the index of characters where boundaries occur.
	* Internally, <code>BreakIterator</code> scans text using a
	* <code>CharacterIterator</code>, and is thus able to scan text held
	* by any object implementing that protocol. A <code>StringCharacterIterator</code>
	* is used to scan <code>String</code> objects passed to <code>setText</code>.
	*
	* <p>
	* You use the factory methods provided by this class to create
	* instances of various types of break iterators. In particular,
	* use <code>getWordInstance</code>, <code>getLineInstance</code>,
	* <code>getSentenceInstance</code>, and <code>getCharacterInstance</code>
	* to create <code>BreakIterator</code>s that perform
	* word, line, sentence, and character boundary analysis respectively.
	* A single <code>BreakIterator</code> can work only on one unit
	* (word, line, sentence, and so on). You must use a different iterator
	* for each unit boundary analysis you wish to perform.
	*
	* <p><a id="line"></a>
	* Line boundary analysis determines where a text string can be
	* broken when line-wrapping. The mechanism correctly handles
	* punctuation and hyphenated words. Actual line breaking needs
	* to also consider the available line width and is handled by
	* higher-level software.
	*
	* <p><a id="sentence"></a>
	* Sentence boundary analysis allows selection with correct interpretation
	* of periods within numbers and abbreviations, and trailing punctuation
	* marks such as quotation marks and parentheses.
	*
	* <p><a id="word"></a>
	* Word boundary analysis is used by search and replace functions, as
	* well as within text editing applications that allow the user to
	* select words with a double click. Word selection provides correct
	* interpretation of punctuation marks within and following
	* words. Characters that are not part of a word, such as symbols
	* or punctuation marks, have word-breaks on both sides.
	*
	* <p><a id="character"></a>
	* Character boundary analysis allows users to interact with characters
	* as they expect to, for example, when moving the cursor through a text
	* string. Character boundary analysis provides correct navigation
	* through character strings, regardless of how the character is stored.
	* The boundaries returned may be those of supplementary characters,
	* combining character sequences, or ligature clusters.
	* For example, an accented character might be stored as a base character
	* and a diacritical mark. What users consider to be a character can
	* differ between languages.
	*
	* <p>
	* The <code>BreakIterator</code> instances returned by the factory methods
	* of this class are intended for use with natural languages only, not for
	* programming language text. It is however possible to define subclasses
	* that tokenize a programming language.
	*
	* <P>
	* <strong>Examples</strong>:<P>
	* Creating and using text boundaries:
	* <blockquote>
	* <pre>
	* public static void main(String args[]) {
	* if (args.length == 1) {
	* String stringToExamine = args[0];
	* //print each word in order
	* BreakIterator boundary = BreakIterator.getWordInstance();
	* boundary.setText(stringToExamine);
	* printEachForward(boundary, stringToExamine);
	* //print each sentence in reverse order
	* boundary = BreakIterator.getSentenceInstance(Locale.US);
	* boundary.setText(stringToExamine);
	* printEachBackward(boundary, stringToExamine);
	* printFirst(boundary, stringToExamine);
	* printLast(boundary, stringToExamine);
	* }
	* }
	* </pre>
	* </blockquote>
	*
	* Print each element in order:
	* <blockquote>
	* <pre>
	* public static void printEachForward(BreakIterator boundary, String source) {
	* int start = boundary.first();
	* for (int end = boundary.next();
	* end != BreakIterator.DONE;
	* start = end, end = boundary.next()) {
	* System.out.println(source.substring(start,end));
	* }
	* }
	* </pre>
	* </blockquote>
	*
	* Print each element in reverse order:
	* <blockquote>
	* <pre>
	* public static void printEachBackward(BreakIterator boundary, String source) {
	* int end = boundary.last();
	* for (int start = boundary.previous();
	* start != BreakIterator.DONE;
	* end = start, start = boundary.previous()) {
	* System.out.println(source.substring(start,end));
	* }
	* }
	* </pre>
	* </blockquote>
	*
	* Print first element:
	* <blockquote>
	* <pre>
	* public static void printFirst(BreakIterator boundary, String source) {
	* int start = boundary.first();
	* int end = boundary.next();
	* System.out.println(source.substring(start,end));
	* }
	* </pre>
	* </blockquote>
	*
	* Print last element:
	* <blockquote>
	* <pre>
	* public static void printLast(BreakIterator boundary, String source) {
	* int end = boundary.last();
	* int start = boundary.previous();
	* System.out.println(source.substring(start,end));
	* }
	* </pre>
	* </blockquote>
	*
	* Print the element at a specified position:
	* <blockquote>
	* <pre>
	* public static void printAt(BreakIterator boundary, int pos, String source) {
	* int end = boundary.following(pos);
	* int start = boundary.previous();
	* System.out.println(source.substring(start,end));
	* }
	* </pre>
	* </blockquote>
	*
	* Find the next word:
	* <blockquote>
	* <pre>{@code
	* public static int nextWordStartAfter(int pos, String text) {
	* BreakIterator wb = BreakIterator.getWordInstance();
	* wb.setText(text);
	* int last = wb.following(pos);
	* int current = wb.next();
	* while (current != BreakIterator.DONE) {
	* for (int p = last; p < current; p++) {
	* if (Character.isLetter(text.codePointAt(p)))
	* return last;
	* }
	* last = current;
	* current = wb.next();
	* }
	* return BreakIterator.DONE;
	* }
	* }</pre>
	* (The iterator returned by BreakIterator.getWordInstance() is unique in that
	* the break positions it returns don't represent both the start and end of the
	* thing being iterated over. That is, a sentence-break iterator returns breaks
	* that each represent the end of one sentence and the beginning of the next.
	* With the word-break iterator, the characters between two boundaries might be a
	* word, or they might be the punctuation or whitespace between two words. The
	* above code uses a simple heuristic to determine which boundary is the beginning
	* of a word: If the characters between this boundary and the next boundary
	* include at least one letter (this can be an alphabetical letter, a CJK ideograph,
	* a Hangul syllable, a Kana character, etc.), then the text between this boundary
	* and the next is a word; otherwise, it's the material between words.)
	* </blockquote>
	*
	* @since 1.1
	* @see CharacterIterator
	*
	*/

	public abstract class BreakIterator implements Cloneable
	{
	/**
	* Constructor. BreakIterator is stateless and has no default behavior.
	*/
	protected BreakIterator()
	{
	}

	/**
	* Create a copy of this iterator
	* @return A copy of this
	*/
	@Override
	public Object clone()
	{
	try {
	return super.clone();
	}
	catch (CloneNotSupportedException e) {
	throw new InternalError(e);
	}
	}

	/**
	* DONE is returned by previous(), next(), next(int), preceding(int)
	* and following(int) when either the first or last text boundary has been
	* reached.
	*/
	public static final int DONE = -1;

	/**
	* Returns the first boundary. The iterator's current position is set
	* to the first text boundary.
	* @return The character index of the first text boundary.
	*/
	public abstract int first();

	/**
	* Returns the last boundary. The iterator's current position is set
	* to the last text boundary.
	* @return The character index of the last text boundary.
	*/
	public abstract int last();

	/**
	* Returns the nth boundary from the current boundary. If either
	* the first or last text boundary has been reached, it returns
	* <code>BreakIterator.DONE</code> and the current position is set to either
	* the first or last text boundary depending on which one is reached. Otherwise,
	* the iterator's current position is set to the new boundary.
	* For example, if the iterator's current position is the mth text boundary
	* and three more boundaries exist from the current boundary to the last text
	* boundary, the next(2) call will return m + 2. The new text position is set
	* to the (m + 2)th text boundary. A next(4) call would return
	* <code>BreakIterator.DONE</code> and the last text boundary would become the
	* new text position.
	* @param n which boundary to return. A value of 0
	* does nothing. Negative values move to previous boundaries
	* and positive values move to later boundaries.
	* @return The character index of the nth boundary from the current position
	* or <code>BreakIterator.DONE</code> if either first or last text boundary
	* has been reached.
	*/
	public abstract int next(int n);

	/**
	* Returns the boundary following the current boundary. If the current boundary
	* is the last text boundary, it returns <code>BreakIterator.DONE</code> and
	* the iterator's current position is unchanged. Otherwise, the iterator's
	* current position is set to the boundary following the current boundary.
	* @return The character index of the next text boundary or
	* <code>BreakIterator.DONE</code> if the current boundary is the last text
	* boundary.
	* Equivalent to next(1).
	* @see #next(int)
	*/
	public abstract int next();

	/**
	* Returns the boundary preceding the current boundary. If the current boundary
	* is the first text boundary, it returns <code>BreakIterator.DONE</code> and
	* the iterator's current position is unchanged. Otherwise, the iterator's
	* current position is set to the boundary preceding the current boundary.
	* @return The character index of the previous text boundary or
	* <code>BreakIterator.DONE</code> if the current boundary is the first text
	* boundary.
	*/
	public abstract int previous();

	/**
	* Returns the first boundary following the specified character offset. If the
	* specified offset equals to the last text boundary, it returns
	* <code>BreakIterator.DONE</code> and the iterator's current position is unchanged.
	* Otherwise, the iterator's current position is set to the returned boundary.
	* The value returned is always greater than the offset or the value
	* <code>BreakIterator.DONE</code>.
	* @param offset the character offset to begin scanning.
	* @return The first boundary after the specified offset or
	* <code>BreakIterator.DONE</code> if the last text boundary is passed in
	* as the offset.
	* @exception IllegalArgumentException if the specified offset is less than
	* the first text boundary or greater than the last text boundary.
	*/
	public abstract int following(int offset);

	/**
	* Returns the last boundary preceding the specified character offset. If the
	* specified offset equals to the first text boundary, it returns
	* <code>BreakIterator.DONE</code> and the iterator's current position is unchanged.
	* Otherwise, the iterator's current position is set to the returned boundary.
	* The value returned is always less than the offset or the value
	* <code>BreakIterator.DONE</code>.
	* @param offset the character offset to begin scanning.
	* @return The last boundary before the specified offset or
	* <code>BreakIterator.DONE</code> if the first text boundary is passed in
	* as the offset.
	* @exception IllegalArgumentException if the specified offset is less than
	* the first text boundary or greater than the last text boundary.
	* @since 1.2
	*/
	public int preceding(int offset) {
	// NOTE: This implementation is here solely because we can't add new
	// abstract methods to an existing class. There is almost ALWAYS a
	// better, faster way to do this.
	int pos = following(offset);
	while (pos >= offset && pos != DONE) {
	pos = previous();
	}
	return pos;
	}

	/**
	* Returns true if the specified character offset is a text boundary.
	* @param offset the character offset to check.
	* @return <code>true</code> if "offset" is a boundary position,
	* <code>false</code> otherwise.
	* @exception IllegalArgumentException if the specified offset is less than
	* the first text boundary or greater than the last text boundary.
	* @since 1.2
	*/
	public boolean isBoundary(int offset) {
	// NOTE: This implementation probably is wrong for most situations
	// because it fails to take into account the possibility that a
	// CharacterIterator passed to setText() may not have a begin offset
	// of 0. But since the abstract BreakIterator doesn't have that
	// knowledge, it assumes the begin offset is 0. If you subclass
	// BreakIterator, copy the SimpleTextBoundary implementation of this
	// function into your subclass. [This should have been abstract at
	// this level, but it's too late to fix that now.]
	if (offset == 0) {
	return true;
	}
	int boundary = following(offset - 1);
	if (boundary == DONE) {
	throw new IllegalArgumentException();
	}
	return boundary == offset;
	}

	/**
	* Returns character index of the text boundary that was most
	* recently returned by next(), next(int), previous(), first(), last(),
	* following(int) or preceding(int). If any of these methods returns
	* <code>BreakIterator.DONE</code> because either first or last text boundary
	* has been reached, it returns the first or last text boundary depending on
	* which one is reached.
	* @return The text boundary returned from the above methods, first or last
	* text boundary.
	* @see #next()
	* @see #next(int)
	* @see #previous()
	* @see #first()
	* @see #last()
	* @see #following(int)
	* @see #preceding(int)
	*/
	public abstract int current();

	/**
	* Get the text being scanned
	* @return the text being scanned
	*/
	public abstract CharacterIterator getText();

	/**
	* Set a new text string to be scanned. The current scan
	* position is reset to first().
	* @param newText new text to scan.
	*/
	public void setText(String newText)
	{
	setText(new StringCharacterIterator(newText));
	}

	/**
	* Set a new text for scanning. The current scan
	* position is reset to first().
	* @param newText new text to scan.
	*/
	public abstract void setText(CharacterIterator newText);

	private static final int CHARACTER_INDEX = 0;
	private static final int WORD_INDEX = 1;
	private static final int LINE_INDEX = 2;
	private static final int SENTENCE_INDEX = 3;

	@SuppressWarnings("unchecked")
	private static final SoftReference<BreakIteratorCache>[] iterCache = (SoftReference<BreakIteratorCache>[]) new SoftReference<?>[4];

	/**
	* Returns a new <code>BreakIterator</code> instance
	* for <a href="BreakIterator.html#word">word breaks</a>
	* for the {@linkplain Locale#getDefault() default locale}.
	* @return A break iterator for word breaks
	*/
	public static BreakIterator getWordInstance()
	{
	return getWordInstance(Locale.getDefault());
	}

	/**
	* Returns a new <code>BreakIterator</code> instance
	* for <a href="BreakIterator.html#word">word breaks</a>
	* for the given locale.
	* @param locale the desired locale
	* @return A break iterator for word breaks
	* @exception NullPointerException if <code>locale</code> is null
	*/
	public static BreakIterator getWordInstance(Locale locale)
	{
	return getBreakInstance(locale, WORD_INDEX);
	}

	/**
	* Returns a new <code>BreakIterator</code> instance
	* for <a href="BreakIterator.html#line">line breaks</a>
	* for the {@linkplain Locale#getDefault() default locale}.
	* @return A break iterator for line breaks
	*/
	public static BreakIterator getLineInstance()
	{
	return getLineInstance(Locale.getDefault());
	}

	/**
	* Returns a new <code>BreakIterator</code> instance
	* for <a href="BreakIterator.html#line">line breaks</a>
	* for the given locale.
	* @param locale the desired locale
	* @return A break iterator for line breaks
	* @exception NullPointerException if <code>locale</code> is null
	*/
	public static BreakIterator getLineInstance(Locale locale)
	{
	return getBreakInstance(locale, LINE_INDEX);
	}

	/**
	* Returns a new <code>BreakIterator</code> instance
	* for <a href="BreakIterator.html#character">character breaks</a>
	* for the {@linkplain Locale#getDefault() default locale}.
	* @return A break iterator for character breaks
	*/
	public static BreakIterator getCharacterInstance()
	{
	return getCharacterInstance(Locale.getDefault());
	}

	/**
	* Returns a new <code>BreakIterator</code> instance
	* for <a href="BreakIterator.html#character">character breaks</a>
	* for the given locale.
	* @param locale the desired locale
	* @return A break iterator for character breaks
	* @exception NullPointerException if <code>locale</code> is null
	*/
	public static BreakIterator getCharacterInstance(Locale locale)
	{
	return getBreakInstance(locale, CHARACTER_INDEX);
	}

	/**
	* Returns a new <code>BreakIterator</code> instance
	* for <a href="BreakIterator.html#sentence">sentence breaks</a>
	* for the {@linkplain Locale#getDefault() default locale}.
	* @return A break iterator for sentence breaks
	*/
	public static BreakIterator getSentenceInstance()
	{
	return getSentenceInstance(Locale.getDefault());
	}

	/**
	* Returns a new <code>BreakIterator</code> instance
	* for <a href="BreakIterator.html#sentence">sentence breaks</a>
	* for the given locale.
	* @param locale the desired locale
	* @return A break iterator for sentence breaks
	* @exception NullPointerException if <code>locale</code> is null
	*/
	public static BreakIterator getSentenceInstance(Locale locale)
	{
	return getBreakInstance(locale, SENTENCE_INDEX);
	}

	private static BreakIterator getBreakInstance(Locale locale, int type) {
	if (iterCache[type] != null) {
	BreakIteratorCache cache = iterCache[type].get();
	if (cache != null) {
	if (cache.getLocale().equals(locale)) {
	return cache.createBreakInstance();
	}
	}
	}

	BreakIterator result = createBreakInstance(locale, type);
	BreakIteratorCache cache = new BreakIteratorCache(locale, result);
	iterCache[type] = new SoftReference<>(cache);
	return result;
	}

	private static BreakIterator createBreakInstance(Locale locale,
	int type) {
	LocaleProviderAdapter adapter = LocaleProviderAdapter.getAdapter(BreakIteratorProvider.class, locale);
	BreakIterator iterator = createBreakInstance(adapter, locale, type);
	if (iterator == null) {
	iterator = createBreakInstance(LocaleProviderAdapter.forJRE(), locale, type);
	}
	return iterator;
	}

	private static BreakIterator createBreakInstance(LocaleProviderAdapter adapter, Locale locale, int type) {
	BreakIteratorProvider breakIteratorProvider = adapter.getBreakIteratorProvider();
	BreakIterator iterator = null;
	switch (type) {
	case CHARACTER_INDEX:
	iterator = breakIteratorProvider.getCharacterInstance(locale);
	break;
	case WORD_INDEX:
	iterator = breakIteratorProvider.getWordInstance(locale);
	break;
	case LINE_INDEX:
	iterator = breakIteratorProvider.getLineInstance(locale);
	break;
	case SENTENCE_INDEX:
	iterator = breakIteratorProvider.getSentenceInstance(locale);
	break;
	}
	return iterator;
	}

	/**
	* Returns an array of all locales for which the
	* <code>get*Instance</code> methods of this class can return
	* localized instances.
	* The returned array represents the union of locales supported by the Java
	* runtime and by installed
	* {@link java.text.spi.BreakIteratorProvider BreakIteratorProvider} implementations.
	* It must contain at least a <code>Locale</code>
	* instance equal to {@link java.util.Locale#US Locale.US}.
	*
	* @return An array of locales for which localized
	* <code>BreakIterator</code> instances are available.
	*/
	public static synchronized Locale[] getAvailableLocales()
	{
	LocaleServiceProviderPool pool =
	LocaleServiceProviderPool.getPool(BreakIteratorProvider.class);
	return pool.getAvailableLocales();
	}

	private static final class BreakIteratorCache {

	private BreakIterator iter;
	private Locale locale;

	BreakIteratorCache(Locale locale, BreakIterator iter) {
	this.locale = locale;
	this.iter = (BreakIterator) iter.clone();
	}

	Locale getLocale() {
	return locale;
	}

	BreakIterator createBreakInstance() {
	return (BreakIterator) iter.clone();
	}
	}
	}

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