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	/*
	* Copyright (c) 1999, 2018, 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.
	*/

	package java.util.regex;

	import java.util.ConcurrentModificationException;
	import java.util.Iterator;
	import java.util.NoSuchElementException;
	import java.util.Objects;
	import java.util.Spliterator;
	import java.util.Spliterators;
	import java.util.function.Consumer;
	import java.util.function.Function;
	import java.util.stream.Stream;
	import java.util.stream.StreamSupport;

	/**
	* An engine that performs match operations on a {@linkplain
	* java.lang.CharSequence character sequence} by interpreting a {@link Pattern}.
	*
	* <p> A matcher is created from a pattern by invoking the pattern's {@link
	* Pattern#matcher matcher} method. Once created, a matcher can be used to
	* perform three different kinds of match operations:
	*
	* <ul>
	*
	* <li><p> The {@link #matches matches} method attempts to match the entire
	* input sequence against the pattern. </p></li>
	*
	* <li><p> The {@link #lookingAt lookingAt} method attempts to match the
	* input sequence, starting at the beginning, against the pattern. </p></li>
	*
	* <li><p> The {@link #find find} method scans the input sequence looking
	* for the next subsequence that matches the pattern. </p></li>
	*
	* </ul>
	*
	* <p> Each of these methods returns a boolean indicating success or failure.
	* More information about a successful match can be obtained by querying the
	* state of the matcher.
	*
	* <p> A matcher finds matches in a subset of its input called the
	* <i>region</i>. By default, the region contains all of the matcher's input.
	* The region can be modified via the {@link #region(int, int) region} method
	* and queried via the {@link #regionStart() regionStart} and {@link
	* #regionEnd() regionEnd} methods. The way that the region boundaries interact
	* with some pattern constructs can be changed. See {@link
	* #useAnchoringBounds(boolean) useAnchoringBounds} and {@link
	* #useTransparentBounds(boolean) useTransparentBounds} for more details.
	*
	* <p> This class also defines methods for replacing matched subsequences with
	* new strings whose contents can, if desired, be computed from the match
	* result. The {@link #appendReplacement appendReplacement} and {@link
	* #appendTail appendTail} methods can be used in tandem in order to collect
	* the result into an existing string buffer or string builder. Alternatively,
	* the more convenient {@link #replaceAll replaceAll} method can be used to
	* create a string in which every matching subsequence in the input sequence
	* is replaced.
	*
	* <p> The explicit state of a matcher includes the start and end indices of
	* the most recent successful match. It also includes the start and end
	* indices of the input subsequence captured by each <a
	* href="Pattern.html#cg">capturing group</a> in the pattern as well as a total
	* count of such subsequences. As a convenience, methods are also provided for
	* returning these captured subsequences in string form.
	*
	* <p> The explicit state of a matcher is initially undefined; attempting to
	* query any part of it before a successful match will cause an {@link
	* IllegalStateException} to be thrown. The explicit state of a matcher is
	* recomputed by every match operation.
	*
	* <p> The implicit state of a matcher includes the input character sequence as
	* well as the <i>append position</i>, which is initially zero and is updated
	* by the {@link #appendReplacement appendReplacement} method.
	*
	* <p> A matcher may be reset explicitly by invoking its {@link #reset()}
	* method or, if a new input sequence is desired, its {@link
	* #reset(java.lang.CharSequence) reset(CharSequence)} method. Resetting a
	* matcher discards its explicit state information and sets the append position
	* to zero.
	*
	* <p> Instances of this class are not safe for use by multiple concurrent
	* threads. </p>
	*
	*
	* @author Mike McCloskey
	* @author Mark Reinhold
	* @author JSR-51 Expert Group
	* @since 1.4
	* @spec JSR-51
	*/

	public final class Matcher implements MatchResult {

	/**
	* The Pattern object that created this Matcher.
	*/
	Pattern parentPattern;

	/**
	* The storage used by groups. They may contain invalid values if
	* a group was skipped during the matching.
	*/
	int[] groups;

	/**
	* The range within the sequence that is to be matched. Anchors
	* will match at these "hard" boundaries. Changing the region
	* changes these values.
	*/
	int from, to;

	/**
	* Lookbehind uses this value to ensure that the subexpression
	* match ends at the point where the lookbehind was encountered.
	*/
	int lookbehindTo;

	/**
	* The original string being matched.
	*/
	CharSequence text;

	/**
	* Matcher state used by the last node. NOANCHOR is used when a
	* match does not have to consume all of the input. ENDANCHOR is
	* the mode used for matching all the input.
	*/
	static final int ENDANCHOR = 1;
	static final int NOANCHOR = 0;
	int acceptMode = NOANCHOR;

	/**
	* The range of string that last matched the pattern. If the last
	* match failed then first is -1; last initially holds 0 then it
	* holds the index of the end of the last match (which is where the
	* next search starts).
	*/
	int first = -1, last = 0;

	/**
	* The end index of what matched in the last match operation.
	*/
	int oldLast = -1;

	/**
	* The index of the last position appended in a substitution.
	*/
	int lastAppendPosition = 0;

	/**
	* Storage used by nodes to tell what repetition they are on in
	* a pattern, and where groups begin. The nodes themselves are stateless,
	* so they rely on this field to hold state during a match.
	*/
	int[] locals;

	/**
	* Storage used by top greedy Loop node to store a specific hash set to
	* keep the beginning index of the failed repetition match. The nodes
	* themselves are stateless, so they rely on this field to hold state
	* during a match.
	*/
	IntHashSet[] localsPos;

	/**
	* Boolean indicating whether or not more input could change
	* the results of the last match.
	*
	* If hitEnd is true, and a match was found, then more input
	* might cause a different match to be found.
	* If hitEnd is true and a match was not found, then more
	* input could cause a match to be found.
	* If hitEnd is false and a match was found, then more input
	* will not change the match.
	* If hitEnd is false and a match was not found, then more
	* input will not cause a match to be found.
	*/
	boolean hitEnd;

	/**
	* Boolean indicating whether or not more input could change
	* a positive match into a negative one.
	*
	* If requireEnd is true, and a match was found, then more
	* input could cause the match to be lost.
	* If requireEnd is false and a match was found, then more
	* input might change the match but the match won't be lost.
	* If a match was not found, then requireEnd has no meaning.
	*/
	boolean requireEnd;

	/**
	* If transparentBounds is true then the boundaries of this
	* matcher's region are transparent to lookahead, lookbehind,
	* and boundary matching constructs that try to see beyond them.
	*/
	boolean transparentBounds = false;

	/**
	* If anchoringBounds is true then the boundaries of this
	* matcher's region match anchors such as ^ and $.
	*/
	boolean anchoringBounds = true;

	/**
	* Number of times this matcher's state has been modified
	*/
	int modCount;

	/**
	* No default constructor.
	*/
	Matcher() {
	}

	/**
	* All matchers have the state used by Pattern during a match.
	*/
	Matcher(Pattern parent, CharSequence text) {
	this.parentPattern = parent;
	this.text = text;

	// Allocate state storage
	int parentGroupCount = Math.max(parent.capturingGroupCount, 10);
	groups = new int[parentGroupCount * 2];
	locals = new int[parent.localCount];
	localsPos = new IntHashSet[parent.localTCNCount];

	// Put fields into initial states
	reset();
	}

	/**
	* Returns the pattern that is interpreted by this matcher.
	*
	* @return The pattern for which this matcher was created
	*/
	public Pattern pattern() {
	return parentPattern;
	}

	/**
	* Returns the match state of this matcher as a {@link MatchResult}.
	* The result is unaffected by subsequent operations performed upon this
	* matcher.
	*
	* @return a {@code MatchResult} with the state of this matcher
	* @since 1.5
	*/
	public MatchResult toMatchResult() {
	return toMatchResult(text.toString());
	}

	private MatchResult toMatchResult(String text) {
	return new ImmutableMatchResult(this.first,
	this.last,
	groupCount(),
	this.groups.clone(),
	text);
	}

	private static class ImmutableMatchResult implements MatchResult {
	private final int first;
	private final int last;
	private final int[] groups;
	private final int groupCount;
	private final String text;

	ImmutableMatchResult(int first, int last, int groupCount,
	int groups[], String text)
	{
	this.first = first;
	this.last = last;
	this.groupCount = groupCount;
	this.groups = groups;
	this.text = text;
	}

	@Override
	public int start() {
	checkMatch();
	return first;
	}

	@Override
	public int start(int group) {
	checkMatch();
	if (group < 0 \|\| group > groupCount)
	throw new IndexOutOfBoundsException("No group " + group);
	return groups[group * 2];
	}

	@Override
	public int end() {
	checkMatch();
	return last;
	}

	@Override
	public int end(int group) {
	checkMatch();
	if (group < 0 \|\| group > groupCount)
	throw new IndexOutOfBoundsException("No group " + group);
	return groups[group * 2 + 1];
	}

	@Override
	public int groupCount() {
	return groupCount;
	}

	@Override
	public String group() {
	checkMatch();
	return group(0);
	}

	@Override
	public String group(int group) {
	checkMatch();
	if (group < 0 \|\| group > groupCount)
	throw new IndexOutOfBoundsException("No group " + group);
	if ((groups[group2] == -1) \|\| (groups[group2+1] == -1))
	return null;
	return text.subSequence(groups[group * 2], groups[group * 2 + 1]).toString();
	}

	private void checkMatch() {
	if (first < 0)
	throw new IllegalStateException("No match found");

	}
	}

	/**
	* Changes the {@code Pattern} that this {@code Matcher} uses to
	* find matches with.
	*
	* <p> This method causes this matcher to lose information
	* about the groups of the last match that occurred. The
	* matcher's position in the input is maintained and its
	* last append position is unaffected.</p>
	*
	* @param newPattern
	* The new pattern used by this matcher
	* @return This matcher
	* @throws IllegalArgumentException
	* If newPattern is {@code null}
	* @since 1.5
	*/
	public Matcher usePattern(Pattern newPattern) {
	if (newPattern == null)
	throw new IllegalArgumentException("Pattern cannot be null");
	parentPattern = newPattern;

	// Reallocate state storage
	int parentGroupCount = Math.max(newPattern.capturingGroupCount, 10);
	groups = new int[parentGroupCount * 2];
	locals = new int[newPattern.localCount];
	for (int i = 0; i < groups.length; i++)
	groups[i] = -1;
	for (int i = 0; i < locals.length; i++)
	locals[i] = -1;
	localsPos = new IntHashSet[parentPattern.localTCNCount];
	modCount++;
	return this;
	}

	/**
	* Resets this matcher.
	*
	* <p> Resetting a matcher discards all of its explicit state information
	* and sets its append position to zero. The matcher's region is set to the
	* default region, which is its entire character sequence. The anchoring
	* and transparency of this matcher's region boundaries are unaffected.
	*
	* @return This matcher
	*/
	public Matcher reset() {
	first = -1;
	last = 0;
	oldLast = -1;
	for(int i=0; i<groups.length; i++)
	groups[i] = -1;
	for(int i=0; i<locals.length; i++)
	locals[i] = -1;
	for (int i = 0; i < localsPos.length; i++) {
	if (localsPos[i] != null)
	localsPos[i].clear();
	}
	lastAppendPosition = 0;
	from = 0;
	to = getTextLength();
	modCount++;
	return this;
	}

	/**
	* Resets this matcher with a new input sequence.
	*
	* <p> Resetting a matcher discards all of its explicit state information
	* and sets its append position to zero. The matcher's region is set to
	* the default region, which is its entire character sequence. The
	* anchoring and transparency of this matcher's region boundaries are
	* unaffected.
	*
	* @param input
	* The new input character sequence
	*
	* @return This matcher
	*/
	public Matcher reset(CharSequence input) {
	text = input;
	return reset();
	}

	/**
	* Returns the start index of the previous match.
	*
	* @return The index of the first character matched
	*
	* @throws IllegalStateException
	* If no match has yet been attempted,
	* or if the previous match operation failed
	*/
	public int start() {
	if (first < 0)
	throw new IllegalStateException("No match available");
	return first;
	}

	/**
	* Returns the start index of the subsequence captured by the given group
	* during the previous match operation.
	*
	* <p> <a href="Pattern.html#cg">Capturing groups</a> are indexed from left
	* to right, starting at one. Group zero denotes the entire pattern, so
	* the expression <i>m.</i>{@code start(0)} is equivalent to
	* <i>m.</i>{@code start()}. </p>
	*
	* @param group
	* The index of a capturing group in this matcher's pattern
	*
	* @return The index of the first character captured by the group,
	* or {@code -1} if the match was successful but the group
	* itself did not match anything
	*
	* @throws IllegalStateException
	* If no match has yet been attempted,
	* or if the previous match operation failed
	*
	* @throws IndexOutOfBoundsException
	* If there is no capturing group in the pattern
	* with the given index
	*/
	public int start(int group) {
	if (first < 0)
	throw new IllegalStateException("No match available");
	if (group < 0 \|\| group > groupCount())
	throw new IndexOutOfBoundsException("No group " + group);
	return groups[group * 2];
	}

	/**
	* Returns the start index of the subsequence captured by the given
	* <a href="Pattern.html#groupname">named-capturing group</a> during the
	* previous match operation.
	*
	* @param name
	* The name of a named-capturing group in this matcher's pattern
	*
	* @return The index of the first character captured by the group,
	* or {@code -1} if the match was successful but the group
	* itself did not match anything
	*
	* @throws IllegalStateException
	* If no match has yet been attempted,
	* or if the previous match operation failed
	*
	* @throws IllegalArgumentException
	* If there is no capturing group in the pattern
	* with the given name
	* @since 1.8
	*/
	public int start(String name) {
	return groups[getMatchedGroupIndex(name) * 2];
	}

	/**
	* Returns the offset after the last character matched.
	*
	* @return The offset after the last character matched
	*
	* @throws IllegalStateException
	* If no match has yet been attempted,
	* or if the previous match operation failed
	*/
	public int end() {
	if (first < 0)
	throw new IllegalStateException("No match available");
	return last;
	}

	/**
	* Returns the offset after the last character of the subsequence
	* captured by the given group during the previous match operation.
	*
	* <p> <a href="Pattern.html#cg">Capturing groups</a> are indexed from left
	* to right, starting at one. Group zero denotes the entire pattern, so
	* the expression <i>m.</i>{@code end(0)} is equivalent to
	* <i>m.</i>{@code end()}. </p>
	*
	* @param group
	* The index of a capturing group in this matcher's pattern
	*
	* @return The offset after the last character captured by the group,
	* or {@code -1} if the match was successful
	* but the group itself did not match anything
	*
	* @throws IllegalStateException
	* If no match has yet been attempted,
	* or if the previous match operation failed
	*
	* @throws IndexOutOfBoundsException
	* If there is no capturing group in the pattern
	* with the given index
	*/
	public int end(int group) {
	if (first < 0)
	throw new IllegalStateException("No match available");
	if (group < 0 \|\| group > groupCount())
	throw new IndexOutOfBoundsException("No group " + group);
	return groups[group * 2 + 1];
	}

	/**
	* Returns the offset after the last character of the subsequence
	* captured by the given <a href="Pattern.html#groupname">named-capturing
	* group</a> during the previous match operation.
	*
	* @param name
	* The name of a named-capturing group in this matcher's pattern
	*
	* @return The offset after the last character captured by the group,
	* or {@code -1} if the match was successful
	* but the group itself did not match anything
	*
	* @throws IllegalStateException
	* If no match has yet been attempted,
	* or if the previous match operation failed
	*
	* @throws IllegalArgumentException
	* If there is no capturing group in the pattern
	* with the given name
	* @since 1.8
	*/
	public int end(String name) {
	return groups[getMatchedGroupIndex(name) * 2 + 1];
	}

	/**
	* Returns the input subsequence matched by the previous match.
	*
	* <p> For a matcher <i>m</i> with input sequence <i>s</i>,
	* the expressions <i>m.</i>{@code group()} and
	* <i>s.</i>{@code substring(}<i>m.</i>{@code start(),} <i>m.</i>
	* {@code end())} are equivalent. </p>
	*
	* <p> Note that some patterns, for example {@code a*}, match the empty
	* string. This method will return the empty string when the pattern
	* successfully matches the empty string in the input. </p>
	*
	* @return The (possibly empty) subsequence matched by the previous match,
	* in string form
	*
	* @throws IllegalStateException
	* If no match has yet been attempted,
	* or if the previous match operation failed
	*/
	public String group() {
	return group(0);
	}

	/**
	* Returns the input subsequence captured by the given group during the
	* previous match operation.
	*
	* <p> For a matcher <i>m</i>, input sequence <i>s</i>, and group index
	* <i>g</i>, the expressions <i>m.</i>{@code group(}<i>g</i>{@code )} and
	* <i>s.</i>{@code substring(}<i>m.</i>{@code start(}<i>g</i>{@code
	* ),} <i>m.</i>{@code end(}<i>g</i>{@code ))}
	* are equivalent. </p>
	*
	* <p> <a href="Pattern.html#cg">Capturing groups</a> are indexed from left
	* to right, starting at one. Group zero denotes the entire pattern, so
	* the expression {@code m.group(0)} is equivalent to {@code m.group()}.
	* </p>
	*
	* <p> If the match was successful but the group specified failed to match
	* any part of the input sequence, then {@code null} is returned. Note
	* that some groups, for example {@code (a*)}, match the empty string.
	* This method will return the empty string when such a group successfully
	* matches the empty string in the input. </p>
	*
	* @param group
	* The index of a capturing group in this matcher's pattern
	*
	* @return The (possibly empty) subsequence captured by the group
	* during the previous match, or {@code null} if the group
	* failed to match part of the input
	*
	* @throws IllegalStateException
	* If no match has yet been attempted,
	* or if the previous match operation failed
	*
	* @throws IndexOutOfBoundsException
	* If there is no capturing group in the pattern
	* with the given index
	*/
	public String group(int group) {
	if (first < 0)
	throw new IllegalStateException("No match found");
	if (group < 0 \|\| group > groupCount())
	throw new IndexOutOfBoundsException("No group " + group);
	if ((groups[group2] == -1) \|\| (groups[group2+1] == -1))
	return null;
	return getSubSequence(groups[group * 2], groups[group * 2 + 1]).toString();
	}

	/**
	* Returns the input subsequence captured by the given
	* <a href="Pattern.html#groupname">named-capturing group</a> during the
	* previous match operation.
	*
	* <p> If the match was successful but the group specified failed to match
	* any part of the input sequence, then {@code null} is returned. Note
	* that some groups, for example {@code (a*)}, match the empty string.
	* This method will return the empty string when such a group successfully
	* matches the empty string in the input. </p>
	*
	* @param name
	* The name of a named-capturing group in this matcher's pattern
	*
	* @return The (possibly empty) subsequence captured by the named group
	* during the previous match, or {@code null} if the group
	* failed to match part of the input
	*
	* @throws IllegalStateException
	* If no match has yet been attempted,
	* or if the previous match operation failed
	*
	* @throws IllegalArgumentException
	* If there is no capturing group in the pattern
	* with the given name
	* @since 1.7
	*/
	public String group(String name) {
	int group = getMatchedGroupIndex(name);
	if ((groups[group2] == -1) \|\| (groups[group2+1] == -1))
	return null;
	return getSubSequence(groups[group * 2], groups[group * 2 + 1]).toString();
	}

	/**
	* Returns the number of capturing groups in this matcher's pattern.
	*
	* <p> Group zero denotes the entire pattern by convention. It is not
	* included in this count.
	*
	* <p> Any non-negative integer smaller than or equal to the value
	* returned by this method is guaranteed to be a valid group index for
	* this matcher. </p>
	*
	* @return The number of capturing groups in this matcher's pattern
	*/
	public int groupCount() {
	return parentPattern.capturingGroupCount - 1;
	}

	/**
	* Attempts to match the entire region against the pattern.
	*
	* <p> If the match succeeds then more information can be obtained via the
	* {@code start}, {@code end}, and {@code group} methods. </p>
	*
	* @return {@code true} if, and only if, the entire region sequence
	* matches this matcher's pattern
	*/
	public boolean matches() {
	return match(from, ENDANCHOR);
	}

	/**
	* Attempts to find the next subsequence of the input sequence that matches
	* the pattern.
	*
	* <p> This method starts at the beginning of this matcher's region, or, if
	* a previous invocation of the method was successful and the matcher has
	* not since been reset, at the first character not matched by the previous
	* match.
	*
	* <p> If the match succeeds then more information can be obtained via the
	* {@code start}, {@code end}, and {@code group} methods. </p>
	*
	* @return {@code true} if, and only if, a subsequence of the input
	* sequence matches this matcher's pattern
	*/
	public boolean find() {
	int nextSearchIndex = last;
	if (nextSearchIndex == first)
	nextSearchIndex++;

	// If next search starts before region, start it at region
	if (nextSearchIndex < from)
	nextSearchIndex = from;

	// If next search starts beyond region then it fails
	if (nextSearchIndex > to) {
	for (int i = 0; i < groups.length; i++)
	groups[i] = -1;
	return false;
	}
	return search(nextSearchIndex);
	}

	/**
	* Resets this matcher and then attempts to find the next subsequence of
	* the input sequence that matches the pattern, starting at the specified
	* index.
	*
	* <p> If the match succeeds then more information can be obtained via the
	* {@code start}, {@code end}, and {@code group} methods, and subsequent
	* invocations of the {@link #find()} method will start at the first
	* character not matched by this match. </p>
	*
	* @param start the index to start searching for a match
	* @throws IndexOutOfBoundsException
	* If start is less than zero or if start is greater than the
	* length of the input sequence.
	*
	* @return {@code true} if, and only if, a subsequence of the input
	* sequence starting at the given index matches this matcher's
	* pattern
	*/
	public boolean find(int start) {
	int limit = getTextLength();
	if ((start < 0) \|\| (start > limit))
	throw new IndexOutOfBoundsException("Illegal start index");
	reset();
	return search(start);
	}

	/**
	* Attempts to match the input sequence, starting at the beginning of the
	* region, against the pattern.
	*
	* <p> Like the {@link #matches matches} method, this method always starts
	* at the beginning of the region; unlike that method, it does not
	* require that the entire region be matched.
	*
	* <p> If the match succeeds then more information can be obtained via the
	* {@code start}, {@code end}, and {@code group} methods. </p>
	*
	* @return {@code true} if, and only if, a prefix of the input
	* sequence matches this matcher's pattern
	*/
	public boolean lookingAt() {
	return match(from, NOANCHOR);
	}

	/**
	* Returns a literal replacement {@code String} for the specified
	* {@code String}.
	*
	* This method produces a {@code String} that will work
	* as a literal replacement {@code s} in the
	* {@code appendReplacement} method of the {@link Matcher} class.
	* The {@code String} produced will match the sequence of characters
	* in {@code s} treated as a literal sequence. Slashes ('\') and
	* dollar signs ('$') will be given no special meaning.
	*
	* @param s The string to be literalized
	* @return A literal string replacement
	* @since 1.5
	*/
	public static String quoteReplacement(String s) {
	if ((s.indexOf('\\') == -1) && (s.indexOf('$') == -1))
	return s;
	StringBuilder sb = new StringBuilder();
	for (int i=0; i<s.length(); i++) {
	char c = s.charAt(i);
	if (c == '\\' \|\| c == '$') {
	sb.append('\\');
	}
	sb.append(c);
	}
	return sb.toString();
	}

	/**
	* Implements a non-terminal append-and-replace step.
	*
	* <p> This method performs the following actions: </p>
	*
	* <ol>
	*
	* <li><p> It reads characters from the input sequence, starting at the
	* append position, and appends them to the given string buffer. It
	* stops after reading the last character preceding the previous match,
	* that is, the character at index {@link
	* #start()} {@code -} {@code 1}. </p></li>
	*
	* <li><p> It appends the given replacement string to the string buffer.
	* </p></li>
	*
	* <li><p> It sets the append position of this matcher to the index of
	* the last character matched, plus one, that is, to {@link #end()}.
	* </p></li>
	*
	* </ol>
	*
	* <p> The replacement string may contain references to subsequences
	* captured during the previous match: Each occurrence of
	* <code>${</code><i>name</i><code>}</code> or {@code $}<i>g</i>
	* will be replaced by the result of evaluating the corresponding
	* {@link #group(String) group(name)} or {@link #group(int) group(g)}
	* respectively. For {@code $}<i>g</i>,
	* the first number after the {@code $} is always treated as part of
	* the group reference. Subsequent numbers are incorporated into g if
	* they would form a legal group reference. Only the numerals '0'
	* through '9' are considered as potential components of the group
	* reference. If the second group matched the string {@code "foo"}, for
	* example, then passing the replacement string {@code "$2bar"} would
	* cause {@code "foobar"} to be appended to the string buffer. A dollar
	* sign ({@code $}) may be included as a literal in the replacement
	* string by preceding it with a backslash ({@code \$}).
	*
	* <p> Note that backslashes ({@code \}) and dollar signs ({@code $}) in
	* the replacement string may cause the results to be different than if it
	* were being treated as a literal replacement string. Dollar signs may be
	* treated as references to captured subsequences as described above, and
	* backslashes are used to escape literal characters in the replacement
	* string.
	*
	* <p> This method is intended to be used in a loop together with the
	* {@link #appendTail(StringBuffer) appendTail} and {@link #find() find}
	* methods. The following code, for example, writes {@code one dog two dogs
	* in the yard} to the standard-output stream: </p>
	*
	* <blockquote><pre>
	* Pattern p = Pattern.compile("cat");
	* Matcher m = p.matcher("one cat two cats in the yard");
	* StringBuffer sb = new StringBuffer();
	* while (m.find()) {
	* m.appendReplacement(sb, "dog");
	* }
	* m.appendTail(sb);
	* System.out.println(sb.toString());</pre></blockquote>
	*
	* @param sb
	* The target string buffer
	*
	* @param replacement
	* The replacement string
	*
	* @return This matcher
	*
	* @throws IllegalStateException
	* If no match has yet been attempted,
	* or if the previous match operation failed
	*
	* @throws IllegalArgumentException
	* If the replacement string refers to a named-capturing
	* group that does not exist in the pattern
	*
	* @throws IndexOutOfBoundsException
	* If the replacement string refers to a capturing group
	* that does not exist in the pattern
	*/
	public Matcher appendReplacement(StringBuffer sb, String replacement) {
	// If no match, return error
	if (first < 0)
	throw new IllegalStateException("No match available");
	StringBuilder result = new StringBuilder();
	appendExpandedReplacement(replacement, result);
	// Append the intervening text
	sb.append(text, lastAppendPosition, first);
	// Append the match substitution
	sb.append(result);
	lastAppendPosition = last;
	modCount++;
	return this;
	}

	/**
	* Implements a non-terminal append-and-replace step.
	*
	* <p> This method performs the following actions: </p>
	*
	* <ol>
	*
	* <li><p> It reads characters from the input sequence, starting at the
	* append position, and appends them to the given string builder. It
	* stops after reading the last character preceding the previous match,
	* that is, the character at index {@link
	* #start()} {@code -} {@code 1}. </p></li>
	*
	* <li><p> It appends the given replacement string to the string builder.
	* </p></li>
	*
	* <li><p> It sets the append position of this matcher to the index of
	* the last character matched, plus one, that is, to {@link #end()}.
	* </p></li>
	*
	* </ol>
	*
	* <p> The replacement string may contain references to subsequences
	* captured during the previous match: Each occurrence of
	* {@code $}<i>g</i> will be replaced by the result of
	* evaluating {@link #group(int) group}{@code (}<i>g</i>{@code )}.
	* The first number after the {@code $} is always treated as part of
	* the group reference. Subsequent numbers are incorporated into g if
	* they would form a legal group reference. Only the numerals '0'
	* through '9' are considered as potential components of the group
	* reference. If the second group matched the string {@code "foo"}, for
	* example, then passing the replacement string {@code "$2bar"} would
	* cause {@code "foobar"} to be appended to the string builder. A dollar
	* sign ({@code $}) may be included as a literal in the replacement
	* string by preceding it with a backslash ({@code \$}).
	*
	* <p> Note that backslashes ({@code \}) and dollar signs ({@code $}) in
	* the replacement string may cause the results to be different than if it
	* were being treated as a literal replacement string. Dollar signs may be
	* treated as references to captured subsequences as described above, and
	* backslashes are used to escape literal characters in the replacement
	* string.
	*
	* <p> This method is intended to be used in a loop together with the
	* {@link #appendTail(StringBuilder) appendTail} and
	* {@link #find() find} methods. The following code, for example, writes
	* {@code one dog two dogs in the yard} to the standard-output stream: </p>
	*
	* <blockquote><pre>
	* Pattern p = Pattern.compile("cat");
	* Matcher m = p.matcher("one cat two cats in the yard");
	* StringBuilder sb = new StringBuilder();
	* while (m.find()) {
	* m.appendReplacement(sb, "dog");
	* }
	* m.appendTail(sb);
	* System.out.println(sb.toString());</pre></blockquote>
	*
	* @param sb
	* The target string builder
	* @param replacement
	* The replacement string
	* @return This matcher
	*
	* @throws IllegalStateException
	* If no match has yet been attempted,
	* or if the previous match operation failed
	* @throws IllegalArgumentException
	* If the replacement string refers to a named-capturing
	* group that does not exist in the pattern
	* @throws IndexOutOfBoundsException
	* If the replacement string refers to a capturing group
	* that does not exist in the pattern
	* @since 9
	*/
	public Matcher appendReplacement(StringBuilder sb, String replacement) {
	// If no match, return error
	if (first < 0)
	throw new IllegalStateException("No match available");
	StringBuilder result = new StringBuilder();
	appendExpandedReplacement(replacement, result);
	// Append the intervening text
	sb.append(text, lastAppendPosition, first);
	// Append the match substitution
	sb.append(result);
	lastAppendPosition = last;
	modCount++;
	return this;
	}

	/**
	* Processes replacement string to replace group references with
	* groups.
	*/
	private StringBuilder appendExpandedReplacement(
	String replacement, StringBuilder result) {
	int cursor = 0;
	while (cursor < replacement.length()) {
	char nextChar = replacement.charAt(cursor);
	if (nextChar == '\\') {
	cursor++;
	if (cursor == replacement.length())
	throw new IllegalArgumentException(
	"character to be escaped is missing");
	nextChar = replacement.charAt(cursor);
	result.append(nextChar);
	cursor++;
	} else if (nextChar == '$') {
	// Skip past $
	cursor++;
	// Throw IAE if this "$" is the last character in replacement
	if (cursor == replacement.length())
	throw new IllegalArgumentException(
	"Illegal group reference: group index is missing");
	nextChar = replacement.charAt(cursor);
	int refNum = -1;
	if (nextChar == '{') {
	cursor++;
	StringBuilder gsb = new StringBuilder();
	while (cursor < replacement.length()) {
	nextChar = replacement.charAt(cursor);
	if (ASCII.isLower(nextChar) \|\|
	ASCII.isUpper(nextChar) \|\|
	ASCII.isDigit(nextChar)) {
	gsb.append(nextChar);
	cursor++;
	} else {
	break;
	}
	}
	if (gsb.length() == 0)
	throw new IllegalArgumentException(
	"named capturing group has 0 length name");
	if (nextChar != '}')
	throw new IllegalArgumentException(
	"named capturing group is missing trailing '}'");
	String gname = gsb.toString();
	if (ASCII.isDigit(gname.charAt(0)))
	throw new IllegalArgumentException(
	"capturing group name {" + gname +
	"} starts with digit character");
	if (!parentPattern.namedGroups().containsKey(gname))
	throw new IllegalArgumentException(
	"No group with name {" + gname + "}");
	refNum = parentPattern.namedGroups().get(gname);
	cursor++;
	} else {
	// The first number is always a group
	refNum = nextChar - '0';
	if ((refNum < 0) \|\| (refNum > 9))
	throw new IllegalArgumentException(
	"Illegal group reference");
	cursor++;
	// Capture the largest legal group string
	boolean done = false;
	while (!done) {
	if (cursor >= replacement.length()) {
	break;
	}
	int nextDigit = replacement.charAt(cursor) - '0';
	if ((nextDigit < 0) \|\| (nextDigit > 9)) { // not a number
	break;
	}
	int newRefNum = (refNum * 10) + nextDigit;
	if (groupCount() < newRefNum) {
	done = true;
	} else {
	refNum = newRefNum;
	cursor++;
	}
	}
	}
	// Append group
	if (start(refNum) != -1 && end(refNum) != -1)
	result.append(text, start(refNum), end(refNum));
	} else {
	result.append(nextChar);
	cursor++;
	}
	}
	return result;
	}

	/**
	* Implements a terminal append-and-replace step.
	*
	* <p> This method reads characters from the input sequence, starting at
	* the append position, and appends them to the given string buffer. It is
	* intended to be invoked after one or more invocations of the {@link
	* #appendReplacement(StringBuffer, String) appendReplacement} method in
	* order to copy the remainder of the input sequence. </p>
	*
	* @param sb
	* The target string buffer
	*
	* @return The target string buffer
	*/
	public StringBuffer appendTail(StringBuffer sb) {
	sb.append(text, lastAppendPosition, getTextLength());
	return sb;
	}

	/**
	* Implements a terminal append-and-replace step.
	*
	* <p> This method reads characters from the input sequence, starting at
	* the append position, and appends them to the given string builder. It is
	* intended to be invoked after one or more invocations of the {@link
	* #appendReplacement(StringBuilder, String)
	* appendReplacement} method in order to copy the remainder of the input
	* sequence. </p>
	*
	* @param sb
	* The target string builder
	*
	* @return The target string builder
	*
	* @since 9
	*/
	public StringBuilder appendTail(StringBuilder sb) {
	sb.append(text, lastAppendPosition, getTextLength());
	return sb;
	}

	/**
	* Replaces every subsequence of the input sequence that matches the
	* pattern with the given replacement string.
	*
	* <p> This method first resets this matcher. It then scans the input
	* sequence looking for matches of the pattern. Characters that are not
	* part of any match are appended directly to the result string; each match
	* is replaced in the result by the replacement string. The replacement
	* string may contain references to captured subsequences as in the {@link
	* #appendReplacement appendReplacement} method.
	*
	* <p> Note that backslashes ({@code \}) and dollar signs ({@code $}) in
	* the replacement string may cause the results to be different than if it
	* were being treated as a literal replacement string. Dollar signs may be
	* treated as references to captured subsequences as described above, and
	* backslashes are used to escape literal characters in the replacement
	* string.
	*
	* <p> Given the regular expression {@code a*b}, the input
	* {@code "aabfooaabfooabfoob"}, and the replacement string
	* {@code "-"}, an invocation of this method on a matcher for that
	* expression would yield the string {@code "-foo-foo-foo-"}.
	*
	* <p> Invoking this method changes this matcher's state. If the matcher
	* is to be used in further matching operations then it should first be
	* reset. </p>
	*
	* @param replacement
	* The replacement string
	*
	* @return The string constructed by replacing each matching subsequence
	* by the replacement string, substituting captured subsequences
	* as needed
	*/
	public String replaceAll(String replacement) {
	reset();
	boolean result = find();
	if (result) {
	StringBuilder sb = new StringBuilder();
	do {
	appendReplacement(sb, replacement);
	result = find();
	} while (result);
	appendTail(sb);
	return sb.toString();
	}
	return text.toString();
	}

	/**
	* Replaces every subsequence of the input sequence that matches the
	* pattern with the result of applying the given replacer function to the
	* match result of this matcher corresponding to that subsequence.
	* Exceptions thrown by the function are relayed to the caller.
	*
	* <p> This method first resets this matcher. It then scans the input
	* sequence looking for matches of the pattern. Characters that are not
	* part of any match are appended directly to the result string; each match
	* is replaced in the result by the applying the replacer function that
	* returns a replacement string. Each replacement string may contain
	* references to captured subsequences as in the {@link #appendReplacement
	* appendReplacement} method.
	*
	* <p> Note that backslashes ({@code \}) and dollar signs ({@code $}) in
	* a replacement string may cause the results to be different than if it
	* were being treated as a literal replacement string. Dollar signs may be
	* treated as references to captured subsequences as described above, and
	* backslashes are used to escape literal characters in the replacement
	* string.
	*
	* <p> Given the regular expression {@code dog}, the input
	* {@code "zzzdogzzzdogzzz"}, and the function
	* {@code mr -> mr.group().toUpperCase()}, an invocation of this method on
	* a matcher for that expression would yield the string
	* {@code "zzzDOGzzzDOGzzz"}.
	*
	* <p> Invoking this method changes this matcher's state. If the matcher
	* is to be used in further matching operations then it should first be
	* reset. </p>
	*
	* <p> The replacer function should not modify this matcher's state during
	* replacement. This method will, on a best-effort basis, throw a
	* {@link java.util.ConcurrentModificationException} if such modification is
	* detected.
	*
	* <p> The state of each match result passed to the replacer function is
	* guaranteed to be constant only for the duration of the replacer function
	* call and only if the replacer function does not modify this matcher's
	* state.
	*
	* @implNote
	* This implementation applies the replacer function to this matcher, which
	* is an instance of {@code MatchResult}.
	*
	* @param replacer
	* The function to be applied to the match result of this matcher
	* that returns a replacement string.
	* @return The string constructed by replacing each matching subsequence
	* with the result of applying the replacer function to that
	* matched subsequence, substituting captured subsequences as
	* needed.
	* @throws NullPointerException if the replacer function is null
	* @throws ConcurrentModificationException if it is detected, on a
	* best-effort basis, that the replacer function modified this
	* matcher's state
	* @since 9
	*/
	public String replaceAll(Function<MatchResult, String> replacer) {
	Objects.requireNonNull(replacer);
	reset();
	boolean result = find();
	if (result) {
	StringBuilder sb = new StringBuilder();
	do {
	int ec = modCount;
	String replacement = replacer.apply(this);
	if (ec != modCount)
	throw new ConcurrentModificationException();
	appendReplacement(sb, replacement);
	result = find();
	} while (result);
	appendTail(sb);
	return sb.toString();
	}
	return text.toString();
	}

	/**
	* Returns a stream of match results for each subsequence of the input
	* sequence that matches the pattern. The match results occur in the
	* same order as the matching subsequences in the input sequence.
	*
	* <p> Each match result is produced as if by {@link #toMatchResult()}.
	*
	* <p> This method does not reset this matcher. Matching starts on
	* initiation of the terminal stream operation either at the beginning of
	* this matcher's region, or, if the matcher has not since been reset, at
	* the first character not matched by a previous match.
	*
	* <p> If the matcher is to be used for further matching operations after
	* the terminal stream operation completes then it should be first reset.
	*
	* <p> This matcher's state should not be modified during execution of the
	* returned stream's pipeline. The returned stream's source
	* {@code Spliterator} is <em>fail-fast</em> and will, on a best-effort
	* basis, throw a {@link java.util.ConcurrentModificationException} if such
	* modification is detected.
	*
	* @return a sequential stream of match results.
	* @since 9
	*/
	public Stream<MatchResult> results() {
	class MatchResultIterator implements Iterator<MatchResult> {
	// -ve for call to find, 0 for not found, 1 for found
	int state = -1;
	// State for concurrent modification checking
	// -1 for uninitialized
	int expectedCount = -1;
	// The input sequence as a string, set once only after first find
	// Avoids repeated conversion from CharSequence for each match
	String textAsString;

	@Override
	public MatchResult next() {
	if (expectedCount >= 0 && expectedCount != modCount)
	throw new ConcurrentModificationException();

	if (!hasNext())
	throw new NoSuchElementException();

	state = -1;
	return toMatchResult(textAsString);
	}

	@Override
	public boolean hasNext() {
	if (state >= 0)
	return state == 1;

	// Defer throwing ConcurrentModificationException to when next
	// or forEachRemaining is called. The is consistent with other
	// fail-fast implementations.
	if (expectedCount >= 0 && expectedCount != modCount)
	return true;

	boolean found = find();
	// Capture the input sequence as a string on first find
	if (found && state < 0)
	textAsString = text.toString();
	state = found ? 1 : 0;
	expectedCount = modCount;
	return found;
	}

	@Override
	public void forEachRemaining(Consumer<? super MatchResult> action) {
	if (expectedCount >= 0 && expectedCount != modCount)
	throw new ConcurrentModificationException();

	int s = state;
	if (s == 0)
	return;

	// Set state to report no more elements on further operations
	state = 0;
	expectedCount = -1;

	// Perform a first find if required
	if (s < 0 && !find())
	return;

	// Capture the input sequence as a string on first find
	textAsString = text.toString();

	do {
	int ec = modCount;
	action.accept(toMatchResult(textAsString));
	if (ec != modCount)
	throw new ConcurrentModificationException();
	} while (find());
	}
	}
	return StreamSupport.stream(Spliterators.spliteratorUnknownSize(
	new MatchResultIterator(), Spliterator.ORDERED \| Spliterator.NONNULL), false);
	}

	/**
	* Replaces the first subsequence of the input sequence that matches the
	* pattern with the given replacement string.
	*
	* <p> This method first resets this matcher. It then scans the input
	* sequence looking for a match of the pattern. Characters that are not
	* part of the match are appended directly to the result string; the match
	* is replaced in the result by the replacement string. The replacement
	* string may contain references to captured subsequences as in the {@link
	* #appendReplacement appendReplacement} method.
	*
	* <p>Note that backslashes ({@code \}) and dollar signs ({@code $}) in
	* the replacement string may cause the results to be different than if it
	* were being treated as a literal replacement string. Dollar signs may be
	* treated as references to captured subsequences as described above, and
	* backslashes are used to escape literal characters in the replacement
	* string.
	*
	* <p> Given the regular expression {@code dog}, the input
	* {@code "zzzdogzzzdogzzz"}, and the replacement string
	* {@code "cat"}, an invocation of this method on a matcher for that
	* expression would yield the string {@code "zzzcatzzzdogzzz"}. </p>
	*
	* <p> Invoking this method changes this matcher's state. If the matcher
	* is to be used in further matching operations then it should first be
	* reset. </p>
	*
	* @param replacement
	* The replacement string
	* @return The string constructed by replacing the first matching
	* subsequence by the replacement string, substituting captured
	* subsequences as needed
	*/
	public String replaceFirst(String replacement) {
	if (replacement == null)
	throw new NullPointerException("replacement");
	reset();
	if (!find())
	return text.toString();
	StringBuilder sb = new StringBuilder();
	appendReplacement(sb, replacement);
	appendTail(sb);
	return sb.toString();
	}

	/**
	* Replaces the first subsequence of the input sequence that matches the
	* pattern with the result of applying the given replacer function to the
	* match result of this matcher corresponding to that subsequence.
	* Exceptions thrown by the replace function are relayed to the caller.
	*
	* <p> This method first resets this matcher. It then scans the input
	* sequence looking for a match of the pattern. Characters that are not
	* part of the match are appended directly to the result string; the match
	* is replaced in the result by the applying the replacer function that
	* returns a replacement string. The replacement string may contain
	* references to captured subsequences as in the {@link #appendReplacement
	* appendReplacement} method.
	*
	* <p>Note that backslashes ({@code \}) and dollar signs ({@code $}) in
	* the replacement string may cause the results to be different than if it
	* were being treated as a literal replacement string. Dollar signs may be
	* treated as references to captured subsequences as described above, and
	* backslashes are used to escape literal characters in the replacement
	* string.
	*
	* <p> Given the regular expression {@code dog}, the input
	* {@code "zzzdogzzzdogzzz"}, and the function
	* {@code mr -> mr.group().toUpperCase()}, an invocation of this method on
	* a matcher for that expression would yield the string
	* {@code "zzzDOGzzzdogzzz"}.
	*
	* <p> Invoking this method changes this matcher's state. If the matcher
	* is to be used in further matching operations then it should first be
	* reset.
	*
	* <p> The replacer function should not modify this matcher's state during
	* replacement. This method will, on a best-effort basis, throw a
	* {@link java.util.ConcurrentModificationException} if such modification is
	* detected.
	*
	* <p> The state of the match result passed to the replacer function is
	* guaranteed to be constant only for the duration of the replacer function
	* call and only if the replacer function does not modify this matcher's
	* state.
	*
	* @implNote
	* This implementation applies the replacer function to this matcher, which
	* is an instance of {@code MatchResult}.
	*
	* @param replacer
	* The function to be applied to the match result of this matcher
	* that returns a replacement string.
	* @return The string constructed by replacing the first matching
	* subsequence with the result of applying the replacer function to
	* the matched subsequence, substituting captured subsequences as
	* needed.
	* @throws NullPointerException if the replacer function is null
	* @throws ConcurrentModificationException if it is detected, on a
	* best-effort basis, that the replacer function modified this
	* matcher's state
	* @since 9
	*/
	public String replaceFirst(Function<MatchResult, String> replacer) {
	Objects.requireNonNull(replacer);
	reset();
	if (!find())
	return text.toString();
	StringBuilder sb = new StringBuilder();
	int ec = modCount;
	String replacement = replacer.apply(this);
	if (ec != modCount)
	throw new ConcurrentModificationException();
	appendReplacement(sb, replacement);
	appendTail(sb);
	return sb.toString();
	}

	/**
	* Sets the limits of this matcher's region. The region is the part of the
	* input sequence that will be searched to find a match. Invoking this
	* method resets the matcher, and then sets the region to start at the
	* index specified by the {@code start} parameter and end at the
	* index specified by the {@code end} parameter.
	*
	* <p>Depending on the transparency and anchoring being used (see
	* {@link #useTransparentBounds(boolean) useTransparentBounds} and
	* {@link #useAnchoringBounds(boolean) useAnchoringBounds}), certain
	* constructs such as anchors may behave differently at or around the
	* boundaries of the region.
	*
	* @param start
	* The index to start searching at (inclusive)
	* @param end
	* The index to end searching at (exclusive)
	* @throws IndexOutOfBoundsException
	* If start or end is less than zero, if
	* start is greater than the length of the input sequence, if
	* end is greater than the length of the input sequence, or if
	* start is greater than end.
	* @return this matcher
	* @since 1.5
	*/
	public Matcher region(int start, int end) {
	if ((start < 0) \|\| (start > getTextLength()))
	throw new IndexOutOfBoundsException("start");
	if ((end < 0) \|\| (end > getTextLength()))
	throw new IndexOutOfBoundsException("end");
	if (start > end)
	throw new IndexOutOfBoundsException("start > end");
	reset();
	from = start;
	to = end;
	return this;
	}

	/**
	* Reports the start index of this matcher's region. The
	* searches this matcher conducts are limited to finding matches
	* within {@link #regionStart() regionStart} (inclusive) and
	* {@link #regionEnd() regionEnd} (exclusive).
	*
	* @return The starting point of this matcher's region
	* @since 1.5
	*/
	public int regionStart() {
	return from;
	}

	/**
	* Reports the end index (exclusive) of this matcher's region.
	* The searches this matcher conducts are limited to finding matches
	* within {@link #regionStart() regionStart} (inclusive) and
	* {@link #regionEnd() regionEnd} (exclusive).
	*
	* @return the ending point of this matcher's region
	* @since 1.5
	*/
	public int regionEnd() {
	return to;
	}

	/**
	* Queries the transparency of region bounds for this matcher.
	*
	* <p> This method returns {@code true} if this matcher uses
	* <i>transparent</i> bounds, {@code false} if it uses <i>opaque</i>
	* bounds.
	*
	* <p> See {@link #useTransparentBounds(boolean) useTransparentBounds} for a
	* description of transparent and opaque bounds.
	*
	* <p> By default, a matcher uses opaque region boundaries.
	*
	* @return {@code true} iff this matcher is using transparent bounds,
	* {@code false} otherwise.
	* @see java.util.regex.Matcher#useTransparentBounds(boolean)
	* @since 1.5
	*/
	public boolean hasTransparentBounds() {
	return transparentBounds;
	}

	/**
	* Sets the transparency of region bounds for this matcher.
	*
	* <p> Invoking this method with an argument of {@code true} will set this
	* matcher to use <i>transparent</i> bounds. If the boolean
	* argument is {@code false}, then <i>opaque</i> bounds will be used.
	*
	* <p> Using transparent bounds, the boundaries of this
	* matcher's region are transparent to lookahead, lookbehind,
	* and boundary matching constructs. Those constructs can see beyond the
	* boundaries of the region to see if a match is appropriate.
	*
	* <p> Using opaque bounds, the boundaries of this matcher's
	* region are opaque to lookahead, lookbehind, and boundary matching
	* constructs that may try to see beyond them. Those constructs cannot
	* look past the boundaries so they will fail to match anything outside
	* of the region.
	*
	* <p> By default, a matcher uses opaque bounds.
	*
	* @param b a boolean indicating whether to use opaque or transparent
	* regions
	* @return this matcher
	* @see java.util.regex.Matcher#hasTransparentBounds
	* @since 1.5
	*/
	public Matcher useTransparentBounds(boolean b) {
	transparentBounds = b;
	return this;
	}

	/**
	* Queries the anchoring of region bounds for this matcher.
	*
	* <p> This method returns {@code true} if this matcher uses
	* <i>anchoring</i> bounds, {@code false} otherwise.
	*
	* <p> See {@link #useAnchoringBounds(boolean) useAnchoringBounds} for a
	* description of anchoring bounds.
	*
	* <p> By default, a matcher uses anchoring region boundaries.
	*
	* @return {@code true} iff this matcher is using anchoring bounds,
	* {@code false} otherwise.
	* @see java.util.regex.Matcher#useAnchoringBounds(boolean)
	* @since 1.5
	*/
	public boolean hasAnchoringBounds() {
	return anchoringBounds;
	}

	/**
	* Sets the anchoring of region bounds for this matcher.
	*
	* <p> Invoking this method with an argument of {@code true} will set this
	* matcher to use <i>anchoring</i> bounds. If the boolean
	* argument is {@code false}, then <i>non-anchoring</i> bounds will be
	* used.
	*
	* <p> Using anchoring bounds, the boundaries of this
	* matcher's region match anchors such as ^ and $.
	*
	* <p> Without anchoring bounds, the boundaries of this
	* matcher's region will not match anchors such as ^ and $.
	*
	* <p> By default, a matcher uses anchoring region boundaries.
	*
	* @param b a boolean indicating whether or not to use anchoring bounds.
	* @return this matcher
	* @see java.util.regex.Matcher#hasAnchoringBounds
	* @since 1.5
	*/
	public Matcher useAnchoringBounds(boolean b) {
	anchoringBounds = b;
	return this;
	}

	/**
	* <p>Returns the string representation of this matcher. The
	* string representation of a {@code Matcher} contains information
	* that may be useful for debugging. The exact format is unspecified.
	*
	* @return The string representation of this matcher
	* @since 1.5
	*/
	public String toString() {
	StringBuilder sb = new StringBuilder();
	sb.append("java.util.regex.Matcher")
	.append("[pattern=").append(pattern())
	.append(" region=")
	.append(regionStart()).append(',').append(regionEnd())
	.append(" lastmatch=");
	if ((first >= 0) && (group() != null)) {
	sb.append(group());
	}
	sb.append(']');
	return sb.toString();
	}

	/**
	* <p>Returns true if the end of input was hit by the search engine in
	* the last match operation performed by this matcher.
	*
	* <p>When this method returns true, then it is possible that more input
	* would have changed the result of the last search.
	*
	* @return true iff the end of input was hit in the last match; false
	* otherwise
	* @since 1.5
	*/
	public boolean hitEnd() {
	return hitEnd;
	}

	/**
	* <p>Returns true if more input could change a positive match into a
	* negative one.
	*
	* <p>If this method returns true, and a match was found, then more
	* input could cause the match to be lost. If this method returns false
	* and a match was found, then more input might change the match but the
	* match won't be lost. If a match was not found, then requireEnd has no
	* meaning.
	*
	* @return true iff more input could change a positive match into a
	* negative one.
	* @since 1.5
	*/
	public boolean requireEnd() {
	return requireEnd;
	}

	/**
	* Initiates a search to find a Pattern within the given bounds.
	* The groups are filled with default values and the match of the root
	* of the state machine is called. The state machine will hold the state
	* of the match as it proceeds in this matcher.
	*
	* Matcher.from is not set here, because it is the "hard" boundary
	* of the start of the search which anchors will set to. The from param
	* is the "soft" boundary of the start of the search, meaning that the
	* regex tries to match at that index but ^ won't match there. Subsequent
	* calls to the search methods start at a new "soft" boundary which is
	* the end of the previous match.
	*/
	boolean search(int from) {
	this.hitEnd = false;
	this.requireEnd = false;
	from = from < 0 ? 0 : from;
	this.first = from;
	this.oldLast = oldLast < 0 ? from : oldLast;
	for (int i = 0; i < groups.length; i++)
	groups[i] = -1;
	for (int i = 0; i < localsPos.length; i++) {
	if (localsPos[i] != null)
	localsPos[i].clear();
	}
	acceptMode = NOANCHOR;
	boolean result = parentPattern.root.match(this, from, text);
	if (!result)
	this.first = -1;
	this.oldLast = this.last;
	this.modCount++;
	return result;
	}

	/**
	* Initiates a search for an anchored match to a Pattern within the given
	* bounds. The groups are filled with default values and the match of the
	* root of the state machine is called. The state machine will hold the
	* state of the match as it proceeds in this matcher.
	*/
	boolean match(int from, int anchor) {
	this.hitEnd = false;
	this.requireEnd = false;
	from = from < 0 ? 0 : from;
	this.first = from;
	this.oldLast = oldLast < 0 ? from : oldLast;
	for (int i = 0; i < groups.length; i++)
	groups[i] = -1;
	for (int i = 0; i < localsPos.length; i++) {
	if (localsPos[i] != null)
	localsPos[i].clear();
	}
	acceptMode = anchor;
	boolean result = parentPattern.matchRoot.match(this, from, text);
	if (!result)
	this.first = -1;
	this.oldLast = this.last;
	this.modCount++;
	return result;
	}

	/**
	* Returns the end index of the text.
	*
	* @return the index after the last character in the text
	*/
	int getTextLength() {
	return text.length();
	}

	/**
	* Generates a String from this matcher's input in the specified range.
	*
	* @param beginIndex the beginning index, inclusive
	* @param endIndex the ending index, exclusive
	* @return A String generated from this matcher's input
	*/
	CharSequence getSubSequence(int beginIndex, int endIndex) {
	return text.subSequence(beginIndex, endIndex);
	}

	/**
	* Returns this matcher's input character at index i.
	*
	* @return A char from the specified index
	*/
	char charAt(int i) {
	return text.charAt(i);
	}

	/**
	* Returns the group index of the matched capturing group.
	*
	* @return the index of the named-capturing group
	*/
	int getMatchedGroupIndex(String name) {
	Objects.requireNonNull(name, "Group name");
	if (first < 0)
	throw new IllegalStateException("No match found");
	if (!parentPattern.namedGroups().containsKey(name))
	throw new IllegalArgumentException("No group with name <" + name + ">");
	return parentPattern.namedGroups().get(name);
	}
	}

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