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	/*
	* Copyright (c) 2019, 2020, 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
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	// (c) 2018 and later: Unicode, Inc. and others.
	// License & terms of use: http://www.unicode.org/copyright.html#License

	// created: 2018may10 Markus W. Scherer

	package jdk.internal.icu.util;

	import java.util.Iterator;
	import java.util.NoSuchElementException;

	/**
	* Abstract map from Unicode code points (U+0000..U+10FFFF) to integer values.
	* This does not implement java.util.Map.
	*
	* @stable ICU 63
	*/
	public abstract class CodePointMap implements Iterable<CodePointMap.Range> {
	/**
	* Selectors for how getRange() should report value ranges overlapping with surrogates.
	* Most users should use NORMAL.
	*
	* @see #getRange
	* @stable ICU 63
	*/
	public enum RangeOption {
	/**
	* getRange() enumerates all same-value ranges as stored in the map.
	* Most users should use this option.
	*
	* @stable ICU 63
	*/
	NORMAL,
	/**
	* getRange() enumerates all same-value ranges as stored in the map,
	* except that lead surrogates (U+D800..U+DBFF) are treated as having the
	* surrogateValue, which is passed to getRange() as a separate parameter.
	* The surrogateValue is not transformed via filter().
	* See {@link Character#isHighSurrogate}.
	*
	* <p>Most users should use NORMAL instead.
	*
	* <p>This option is useful for maps that map surrogate code units to
	* special values optimized for UTF-16 string processing
	* or for special error behavior for unpaired surrogates,
	* but those values are not to be associated with the lead surrogate code points.
	*
	* @stable ICU 63
	*/
	FIXED_LEAD_SURROGATES,
	/**
	* getRange() enumerates all same-value ranges as stored in the map,
	* except that all surrogates (U+D800..U+DFFF) are treated as having the
	* surrogateValue, which is passed to getRange() as a separate parameter.
	* The surrogateValue is not transformed via filter().
	* See {@link Character#isSurrogate}.
	*
	* <p>Most users should use NORMAL instead.
	*
	* <p>This option is useful for maps that map surrogate code units to
	* special values optimized for UTF-16 string processing
	* or for special error behavior for unpaired surrogates,
	* but those values are not to be associated with the lead surrogate code points.
	*
	* @stable ICU 63
	*/
	FIXED_ALL_SURROGATES
	}

	/**
	* Callback function interface: Modifies a map value.
	* Optionally called by getRange().
	* The modified value will be returned by the getRange() function.
	*
	* <p>Can be used to ignore some of the value bits,
	* make a filter for one of several values,
	* return a value index computed from the map value, etc.
	*
	* @see #getRange
	* @see #iterator
	* @stable ICU 63
	*/
	public interface ValueFilter {
	/**
	* Modifies the map value.
	*
	* @param value map value
	* @return modified value
	* @stable ICU 63
	*/
	public int apply(int value);
	}

	/**
	* Range iteration result data.
	* Code points from start to end map to the same value.
	* The value may have been modified by {@link ValueFilter#apply(int)},
	* or it may be the surrogateValue if a RangeOption other than "normal" was used.
	*
	* @see #getRange
	* @see #iterator
	* @stable ICU 63
	*/
	public static final class Range {
	private int start;
	private int end;
	private int value;

	/**
	* Constructor. Sets start and end to -1 and value to 0.
	*
	* @stable ICU 63
	*/
	public Range() {
	start = end = -1;
	value = 0;
	}

	/**
	* @return the start code point
	* @stable ICU 63
	*/
	public int getStart() { return start; }
	/**
	* @return the (inclusive) end code point
	* @stable ICU 63
	*/
	public int getEnd() { return end; }
	/**
	* @return the range value
	* @stable ICU 63
	*/
	public int getValue() { return value; }
	/**
	* Sets the range. When using {@link #iterator()},
	* iteration will resume after the newly set end.
	*
	* @param start new start code point
	* @param end new end code point
	* @param value new value
	* @stable ICU 63
	*/
	public void set(int start, int end, int value) {
	this.start = start;
	this.end = end;
	this.value = value;
	}
	}

	private final class RangeIterator implements Iterator<Range> {
	private Range range = new Range();

	@Override
	public boolean hasNext() {
	return -1 <= range.end && range.end < 0x10ffff;
	}

	@Override
	public Range next() {
	if (getRange(range.end + 1, null, range)) {
	return range;
	} else {
	throw new NoSuchElementException();
	}
	}

	@Override
	public final void remove() {
	throw new UnsupportedOperationException();
	}
	}

	/**
	* Iterates over code points of a string and fetches map values.
	* This does not implement java.util.Iterator.
	*
	* <pre>
	* void onString(CodePointMap map, CharSequence s, int start) {
	* CodePointMap.StringIterator iter = map.stringIterator(s, start);
	* while (iter.next()) {
	* int end = iter.getIndex(); // code point from between start and end
	* useValue(s, start, end, iter.getCodePoint(), iter.getValue());
	* start = end;
	* }
	* }
	* </pre>
	*
	* <p>This class is not intended for public subclassing.
	*
	* @stable ICU 63
	*/
	public class StringIterator {
	/**
	* @internal
	* @deprecated This API is ICU internal only.
	*/
	@Deprecated
	protected CharSequence s;
	/**
	* @internal
	* @deprecated This API is ICU internal only.
	*/
	@Deprecated
	protected int sIndex;
	/**
	* @internal
	* @deprecated This API is ICU internal only.
	*/
	@Deprecated
	protected int c;
	/**
	* @internal
	* @deprecated This API is ICU internal only.
	*/
	@Deprecated
	protected int value;

	/**
	* @internal
	* @deprecated This API is ICU internal only.
	*/
	@Deprecated
	protected StringIterator(CharSequence s, int sIndex) {
	this.s = s;
	this.sIndex = sIndex;
	c = -1;
	value = 0;
	}

	/**
	* Resets the iterator to a new string and/or a new string index.
	*
	* @param s string to iterate over
	* @param sIndex string index where the iteration will start
	* @stable ICU 63
	*/
	public void reset(CharSequence s, int sIndex) {
	this.s = s;
	this.sIndex = sIndex;
	c = -1;
	value = 0;
	}

	/**
	* Reads the next code point, post-increments the string index,
	* and gets a value from the map.
	* Sets an implementation-defined error value if the code point is an unpaired surrogate.
	*
	* @return true if the string index was not yet at the end of the string;
	* otherwise the iterator did not advance
	* @stable ICU 63
	*/
	public boolean next() {
	if (sIndex >= s.length()) {
	return false;
	}
	c = Character.codePointAt(s, sIndex);
	sIndex += Character.charCount(c);
	value = get(c);
	return true;
	}

	/**
	* Reads the previous code point, pre-decrements the string index,
	* and gets a value from the map.
	* Sets an implementation-defined error value if the code point is an unpaired surrogate.
	*
	* @return true if the string index was not yet at the start of the string;
	* otherwise the iterator did not advance
	* @stable ICU 63
	*/
	public boolean previous() {
	if (sIndex <= 0) {
	return false;
	}
	c = Character.codePointBefore(s, sIndex);
	sIndex -= Character.charCount(c);
	value = get(c);
	return true;
	}
	/**
	* @return the string index
	* @stable ICU 63
	*/
	public final int getIndex() { return sIndex; }
	/**
	* @return the code point
	* @stable ICU 63
	*/
	public final int getCodePoint() { return c; }
	/**
	* @return the map value,
	* or an implementation-defined error value if
	* the code point is an unpaired surrogate
	* @stable ICU 63
	*/
	public final int getValue() { return value; }
	}

	/**
	* Protected no-args constructor.
	*
	* @stable ICU 63
	*/
	protected CodePointMap() {
	}

	/**
	* Returns the value for a code point as stored in the map, with range checking.
	* Returns an implementation-defined error value if c is not in the range 0..U+10FFFF.
	*
	* @param c the code point
	* @return the map value,
	* or an implementation-defined error value if
	* the code point is not in the range 0..U+10FFFF
	* @stable ICU 63
	*/
	public abstract int get(int c);

	/**
	* Sets the range object to a range of code points beginning with the start parameter.
	* The range start is the same as the start input parameter
	* (even if there are preceding code points that have the same value).
	* The range end is the last code point such that
	* all those from start to there have the same value.
	* Returns false if start is not 0..U+10FFFF.
	* Can be used to efficiently iterate over all same-value ranges in a map.
	* (This is normally faster than iterating over code points and get()ting each value,
	* but may be much slower than a data structure that stores ranges directly.)
	*
	* <p>If the {@link ValueFilter} parameter is not null, then
	* the value to be delivered is passed through that filter, and the return value is the end
	* of the range where all values are modified to the same actual value.
	* The value is unchanged if that parameter is null.
	*
	* <p>Example:
	* <pre>
	* int start = 0;
	* CodePointMap.Range range = new CodePointMap.Range();
	* while (map.getRange(start, null, range)) {
	* int end = range.getEnd();
	* int value = range.getValue();
	* // Work with the range start..end and its value.
	* start = end + 1;
	* }
	* </pre>
	*
	* @param start range start
	* @param filter an object that may modify the map data value,
	* or null if the values from the map are to be used unmodified
	* @param range the range object that will be set to the code point range and value
	* @return true if start is 0..U+10FFFF; otherwise no new range is fetched
	* @stable ICU 63
	*/
	public abstract boolean getRange(int start, ValueFilter filter, Range range);

	/**
	* Sets the range object to a range of code points beginning with the start parameter.
	* The range start is the same as the start input parameter
	* (even if there are preceding code points that have the same value).
	* The range end is the last code point such that
	* all those from start to there have the same value.
	* Returns false if start is not 0..U+10FFFF.
	*
	* <p>Same as the simpler {@link #getRange(int, ValueFilter, Range)} but optionally
	* modifies the range if it overlaps with surrogate code points.
	*
	* @param start range start
	* @param option defines whether surrogates are treated normally,
	* or as having the surrogateValue; usually {@link RangeOption#NORMAL}
	* @param surrogateValue value for surrogates; ignored if option=={@link RangeOption#NORMAL}
	* @param filter an object that may modify the map data value,
	* or null if the values from the map are to be used unmodified
	* @param range the range object that will be set to the code point range and value
	* @return true if start is 0..U+10FFFF; otherwise no new range is fetched
	* @stable ICU 63
	*/
	public boolean getRange(int start, RangeOption option, int surrogateValue,
	ValueFilter filter, Range range) {
	assert option != null;
	if (!getRange(start, filter, range)) {
	return false;
	}
	if (option == RangeOption.NORMAL) {
	return true;
	}
	int surrEnd = option == RangeOption.FIXED_ALL_SURROGATES ? 0xdfff : 0xdbff;
	int end = range.end;
	if (end < 0xd7ff \|\| start > surrEnd) {
	return true;
	}
	// The range overlaps with surrogates, or ends just before the first one.
	if (range.value == surrogateValue) {
	if (end >= surrEnd) {
	// Surrogates followed by a non-surrValue range,
	// or surrogates are part of a larger surrValue range.
	return true;
	}
	} else {
	if (start <= 0xd7ff) {
	range.end = 0xd7ff; // Non-surrValue range ends before surrValue surrogates.
	return true;
	}
	// Start is a surrogate with a non-surrValue code unit value.
	// Return a surrValue code point range.
	range.value = surrogateValue;
	if (end > surrEnd) {
	range.end = surrEnd; // Surrogate range ends before non-surrValue rest of range.
	return true;
	}
	}
	// See if the surrValue surrogate range can be merged with
	// an immediately following range.
	if (getRange(surrEnd + 1, filter, range) && range.value == surrogateValue) {
	range.start = start;
	return true;
	}
	range.start = start;
	range.end = surrEnd;
	range.value = surrogateValue;
	return true;
	}

	/**
	* Convenience iterator over same-map-value code point ranges.
	* Same as looping over all ranges with {@link #getRange(int, ValueFilter, Range)}
	* without filtering.
	* Adjacent ranges have different map values.
	*
	* <p>The iterator always returns the same Range object.
	*
	* @return a Range iterator
	* @stable ICU 63
	*/
	@Override
	public Iterator<Range> iterator() {
	return new RangeIterator();
	}

	/**
	* Returns an iterator (not a java.util.Iterator) over code points of a string
	* for fetching map values.
	*
	* @param s string to iterate over
	* @param sIndex string index where the iteration will start
	* @return the iterator
	* @stable ICU 63
	*/
	public StringIterator stringIterator(CharSequence s, int sIndex) {
	return new StringIterator(s, sIndex);
	}
	}

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