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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.text.Normalizer;
	import java.text.Normalizer.Form;
	import java.util.Locale;
	import java.util.Iterator;
	import java.util.Map;
	import java.util.ArrayList;
	import java.util.HashMap;
	import java.util.LinkedHashSet;
	import java.util.List;
	import java.util.Set;
	import java.util.Arrays;
	import java.util.NoSuchElementException;
	import java.util.Spliterator;
	import java.util.Spliterators;
	import java.util.function.Predicate;
	import java.util.stream.Stream;
	import java.util.stream.StreamSupport;


	/**
	* A compiled representation of a regular expression.
	*
	* <p> A regular expression, specified as a string, must first be compiled into
	* an instance of this class. The resulting pattern can then be used to create
	* a {@link Matcher} object that can match arbitrary {@linkplain
	* java.lang.CharSequence character sequences} against the regular
	* expression. All of the state involved in performing a match resides in the
	* matcher, so many matchers can share the same pattern.
	*
	* <p> A typical invocation sequence is thus
	*
	* <blockquote><pre>
	* Pattern p = Pattern.{@link #compile compile}("a*b");
	* Matcher m = p.{@link #matcher matcher}("aaaaab");
	* boolean b = m.{@link Matcher#matches matches}();</pre></blockquote>
	*
	* <p> A {@link #matches matches} method is defined by this class as a
	* convenience for when a regular expression is used just once. This method
	* compiles an expression and matches an input sequence against it in a single
	* invocation. The statement
	*
	* <blockquote><pre>
	* boolean b = Pattern.matches("a*b", "aaaaab");</pre></blockquote>
	*
	* is equivalent to the three statements above, though for repeated matches it
	* is less efficient since it does not allow the compiled pattern to be reused.
	*
	* <p> Instances of this class are immutable and are safe for use by multiple
	* concurrent threads. Instances of the {@link Matcher} class are not safe for
	* such use.
	*
	*
	* <h3><a id="sum">Summary of regular-expression constructs</a></h3>
	*
	* <table class="borderless">
	* <caption style="display:none">Regular expression constructs, and what they match</caption>
	* <thead style="text-align:left">
	* <tr>
	* <th id="construct">Construct</th>
	* <th id="matches">Matches</th>
	* </tr>
	* </thead>
	* <tbody style="text-align:left">
	*
	* <tr><th colspan="2" style="padding-top:20px" id="characters">Characters</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight: normal" id="x"><i>x</i></th>
	* <td headers="matches characters x">The character <i>x</i></td></tr>
	* <tr><th style="vertical-align:top; font-weight: normal" id="backslash">{@code \\}</th>
	* <td headers="matches characters backslash">The backslash character</td></tr>
	* <tr><th style="vertical-align:top; font-weight: normal" id="octal_n">{@code \0}<i>n</i></th>
	* <td headers="matches characters octal_n">The character with octal value {@code 0}<i>n</i>
	* (0 {@code <=} <i>n</i> {@code <=} 7)</td></tr>
	* <tr><th style="vertical-align:top; font-weight: normal" id="octal_nn">{@code \0}<i>nn</i></th>
	* <td headers="matches characters octal_nn">The character with octal value {@code 0}<i>nn</i>
	* (0 {@code <=} <i>n</i> {@code <=} 7)</td></tr>
	* <tr><th style="vertical-align:top; font-weight: normal" id="octal_nnn">{@code \0}<i>mnn</i></th>
	* <td headers="matches characters octal_nnn">The character with octal value {@code 0}<i>mnn</i>
	* (0 {@code <=} <i>m</i> {@code <=} 3,
	* 0 {@code <=} <i>n</i> {@code <=} 7)</td></tr>
	* <tr><th style="vertical-align:top; font-weight: normal" id="hex_hh">{@code \x}<i>hh</i></th>
	* <td headers="matches characters hex_hh">The character with hexadecimal value {@code 0x}<i>hh</i></td></tr>
	* <tr><th style="vertical-align:top; font-weight: normal" id="hex_hhhh"><code>\u</code><i>hhhh</i></th>
	* <td headers="matches characters hex_hhhh">The character with hexadecimal value {@code 0x}<i>hhhh</i></td></tr>
	* <tr><th style="vertical-align:top; font-weight: normal" id="hex_h_h"><code>\x</code><i>{h...h}</i></th>
	* <td headers="matches characters hex_h_h">The character with hexadecimal value {@code 0x}<i>h...h</i>
	* ({@link java.lang.Character#MIN_CODE_POINT Character.MIN_CODE_POINT}
	*  <= {@code 0x}<i>h...h</i> <=
	* {@link java.lang.Character#MAX_CODE_POINT Character.MAX_CODE_POINT})</td></tr>
	* <tr><th style="vertical-align:top; font-weight: normal" id="unicode_name"><code>\N{</code><i>name</i><code>}</code></th>
	* <td headers="matches characters unicode_name">The character with Unicode character name <i>'name'</i></td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="tab">{@code \t}</th>
	* <td headers="matches characters tab">The tab character (<code>'\u0009'</code>)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="newline">{@code \n}</th>
	* <td headers="matches characters newline">The newline (line feed) character (<code>'\u000A'</code>)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="return">{@code \r}</th>
	* <td headers="matches characters return">The carriage-return character (<code>'\u000D'</code>)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="form_feed">{@code \f}</th>
	* <td headers="matches characters form_feed">The form-feed character (<code>'\u000C'</code>)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="bell">{@code \a}</th>
	* <td headers="matches characters bell">The alert (bell) character (<code>'\u0007'</code>)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="escape">{@code \e}</th>
	* <td headers="matches characters escape">The escape character (<code>'\u001B'</code>)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="ctrl_x">{@code \c}<i>x</i></th>
	* <td headers="matches characters ctrl_x">The control character corresponding to <i>x</i></td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="classes">Character classes</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="simple">{@code [abc]}</th>
	* <td headers="matches classes simple">{@code a}, {@code b}, or {@code c} (simple class)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="negation">{@code [^abc]}</th>
	* <td headers="matches classes negation">Any character except {@code a}, {@code b}, or {@code c} (negation)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="range">{@code [a-zA-Z]}</th>
	* <td headers="matches classes range">{@code a} through {@code z}
	* or {@code A} through {@code Z}, inclusive (range)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="union">{@code [a-d[m-p]]}</th>
	* <td headers="matches classes union">{@code a} through {@code d},
	* or {@code m} through {@code p}: {@code [a-dm-p]} (union)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="intersection">{@code [a-z&&[def]]}</th>
	* <td headers="matches classes intersection">{@code d}, {@code e}, or {@code f} (intersection)</tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="subtraction1">{@code [a-z&&[^bc]]}</th>
	* <td headers="matches classes subtraction1">{@code a} through {@code z},
	* except for {@code b} and {@code c}: {@code [ad-z]} (subtraction)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="subtraction2">{@code [a-z&&[^m-p]]}</th>
	* <td headers="matches classes subtraction2">{@code a} through {@code z},
	* and not {@code m} through {@code p}: {@code [a-lq-z]}(subtraction)</td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="predef">Predefined character classes</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="any">{@code .}</th>
	* <td headers="matches predef any">Any character (may or may not match <a href="#lt">line terminators</a>)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="digit">{@code \d}</th>
	* <td headers="matches predef digit">A digit: {@code [0-9]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="non_digit">{@code \D}</th>
	* <td headers="matches predef non_digit">A non-digit: {@code [^0-9]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="horiz_white">{@code \h}</th>
	* <td headers="matches predef horiz_white">A horizontal whitespace character:
	* <code>[ \t\xA0\u1680\u180e\u2000-\u200a\u202f\u205f\u3000]</code></td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="non_horiz_white">{@code \H}</th>
	* <td headers="matches predef non_horiz_white">A non-horizontal whitespace character: {@code [^\h]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="white">{@code \s}</th>
	* <td headers="matches predef white">A whitespace character: {@code [ \t\n\x0B\f\r]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="non_white">{@code \S}</th>
	* <td headers="matches predef non_white">A non-whitespace character: {@code [^\s]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="vert_white">{@code \v}</th>
	* <td headers="matches predef vert_white">A vertical whitespace character: <code>[\n\x0B\f\r\x85\u2028\u2029]</code>
	* </td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="non_vert_white">{@code \V}</th>
	* <td headers="matches predef non_vert_white">A non-vertical whitespace character: {@code [^\v]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="word">{@code \w}</th>
	* <td headers="matches predef word">A word character: {@code [a-zA-Z_0-9]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="non_word">{@code \W}</th>
	* <td headers="matches predef non_word">A non-word character: {@code [^\w]}</td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="posix"><b>POSIX character classes (US-ASCII only)</b></th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="Lower">{@code \p{Lower}}</th>
	* <td headers="matches posix Lower">A lower-case alphabetic character: {@code [a-z]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="Upper">{@code \p{Upper}}</th>
	* <td headers="matches posix Upper">An upper-case alphabetic character:{@code [A-Z]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="ASCII">{@code \p{ASCII}}</th>
	* <td headers="matches posix ASCII">All ASCII:{@code [\x00-\x7F]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="Alpha">{@code \p{Alpha}}</th>
	* <td headers="matches posix Alpha">An alphabetic character:{@code [\p{Lower}\p{Upper}]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="Digit">{@code \p{Digit}}</th>
	* <td headers="matches posix Digit">A decimal digit: {@code [0-9]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="Alnum">{@code \p{Alnum}}</th>
	* <td headers="matches posix Alnum">An alphanumeric character:{@code [\p{Alpha}\p{Digit}]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="Punct">{@code \p{Punct}}</th>
	* <td headers="matches posix Punct">Punctuation: One of {@code !"#$%&'()*+,-./:;<=>?@[\]^_`{\|}~}</td></tr>
	* <!-- {@code [\!"#\$%&'\*\+,\-\./:;\<=\>\?@\[\\\]\^_`\{\\|\}~]}
	* {@code [\X21-\X2F\X31-\X40\X5B-\X60\X7B-\X7E]} -->
	* <tr><th style="vertical-align:top; font-weight:normal" id="Graph">{@code \p{Graph}}</th>
	* <td headers="matches posix Graph">A visible character: {@code [\p{Alnum}\p{Punct}]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="Print">{@code \p{Print}}</th>
	* <td headers="matches posix Print">A printable character: {@code [\p{Graph}\x20]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="Blank">{@code \p{Blank}}</th>
	* <td headers="matches posix Blank">A space or a tab: {@code [ \t]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="Cntrl">{@code \p{Cntrl}}</th>
	* <td headers="matches posix Cntrl">A control character: {@code [\x00-\x1F\x7F]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="XDigit">{@code \p{XDigit}}</th>
	* <td headers="matches posix XDigit">A hexadecimal digit: {@code [0-9a-fA-F]}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="Space">{@code \p{Space}}</th>
	* <td headers="matches posix Space">A whitespace character: {@code [ \t\n\x0B\f\r]}</td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="java">java.lang.Character classes (simple <a href="#jcc">java character type</a>)</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="javaLowerCase">{@code \p{javaLowerCase}}</th>
	* <td headers="matches java javaLowerCase">Equivalent to java.lang.Character.isLowerCase()</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="javaUpperCase">{@code \p{javaUpperCase}}</th>
	* <td headers="matches java javaUpperCase">Equivalent to java.lang.Character.isUpperCase()</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="javaWhitespace">{@code \p{javaWhitespace}}</th>
	* <td headers="matches java javaWhitespace">Equivalent to java.lang.Character.isWhitespace()</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="javaMirrored">{@code \p{javaMirrored}}</th>
	* <td headers="matches java javaMirrored">Equivalent to java.lang.Character.isMirrored()</td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="unicode">Classes for Unicode scripts, blocks, categories and binary properties</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="IsLatin">{@code \p{IsLatin}}</th>
	* <td headers="matches unicode IsLatin">A Latin script character (<a href="#usc">script</a>)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="InGreek">{@code \p{InGreek}}</th>
	* <td headers="matches unicode InGreek">A character in the Greek block (<a href="#ubc">block</a>)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="Lu">{@code \p{Lu}}</th>
	* <td headers="matches unicode Lu">An uppercase letter (<a href="#ucc">category</a>)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="IsAlphabetic">{@code \p{IsAlphabetic}}</th>
	* <td headers="matches unicode IsAlphabetic">An alphabetic character (<a href="#ubpc">binary property</a>)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="Sc">{@code \p{Sc}}</th>
	* <td headers="matches unicode Sc">A currency symbol</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="not_InGreek">{@code \P{InGreek}}</th>
	* <td headers="matches unicode not_InGreek">Any character except one in the Greek block (negation)</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="not_uppercase">{@code [\p{L}&&[^\p{Lu}]]}</th>
	* <td headers="matches unicode not_uppercase">Any letter except an uppercase letter (subtraction)</td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="bounds">Boundary matchers</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="begin_line">{@code ^}</th>
	* <td headers="matches bounds begin_line">The beginning of a line</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="end_line">{@code $}</th>
	* <td headers="matches bounds end_line">The end of a line</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="word_boundary">{@code \b}</th>
	* <td headers="matches bounds word_boundary">A word boundary</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="grapheme_cluster_boundary">{@code \b{g}}</th>
	* <td headers="matches bounds grapheme_cluster_boundary">A Unicode extended grapheme cluster boundary</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="non_word_boundary">{@code \B}</th>
	* <td headers="matches bounds non_word_boundary">A non-word boundary</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="begin_input">{@code \A}</th>
	* <td headers="matches bounds begin_input">The beginning of the input</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="end_prev_match">{@code \G}</th>
	* <td headers="matches bounds end_prev_match">The end of the previous match</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="end_input_except_term">{@code \Z}</th>
	* <td headers="matches bounds end_input_except_term">The end of the input but for the final
	* <a href="#lt">terminator</a>, if any</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="end_input">{@code \z}</th>
	* <td headers="matches bounds end_input">The end of the input</td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="linebreak">Linebreak matcher</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="any_unicode_linebreak">{@code \R}</th>
	* <td headers="matches linebreak any_unicode_linebreak">Any Unicode linebreak sequence, is equivalent to
	* <code>\u000D\u000A\|[\u000A\u000B\u000C\u000D\u0085\u2028\u2029]
	* </code></td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="grapheme">Unicode Extended Grapheme matcher</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="grapheme_any">{@code \X}</th>
	* <td headers="matches grapheme grapheme_any">Any Unicode extended grapheme cluster</td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="greedy">Greedy quantifiers</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="greedy_once_or_not"><i>X</i>{@code ?}</th>
	* <td headers="matches greedy greedy_once_or_not"><i>X</i>, once or not at all</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="greedy_zero_or_more"><i>X</i>{@code *}</th>
	* <td headers="matches greedy greedy_zero_or_more"><i>X</i>, zero or more times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="greedy_one_or_more"><i>X</i>{@code +}</th>
	* <td headers="matches greedy greedy_one_or_more"><i>X</i>, one or more times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="greedy_exactly"><i>X</i><code>{</code><i>n</i><code>}</code></th>
	* <td headers="matches greedy greedy_exactly"><i>X</i>, exactly <i>n</i> times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="greedy_at_least"><i>X</i><code>{</code><i>n</i>{@code ,}}</th>
	* <td headers="matches greedy greedy_at_least"><i>X</i>, at least <i>n</i> times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="greedy_at_least_up_to"><i>X</i><code>{</code><i>n</i>{@code ,}<i>m</i><code>}</code></th>
	* <td headers="matches greedy greedy_at_least_up_to"><i>X</i>, at least <i>n</i> but not more than <i>m</i> times</td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="reluc">Reluctant quantifiers</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="reluc_once_or_not"><i>X</i>{@code ??}</th>
	* <td headers="matches reluc reluc_once_or_not"><i>X</i>, once or not at all</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="reluc_zero_or_more"><i>X</i>{@code *?}</th>
	* <td headers="matches reluc reluc_zero_or_more"><i>X</i>, zero or more times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="reluc_one_or_more"><i>X</i>{@code +?}</th>
	* <td headers="matches reluc reluc_one_or_more"><i>X</i>, one or more times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="reluc_exactly"><i>X</i><code>{</code><i>n</i><code>}?</code></th>
	* <td headers="matches reluc reluc_exactly"><i>X</i>, exactly <i>n</i> times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="reluc_at_least"><i>X</i><code>{</code><i>n</i><code>,}?</code></th>
	* <td headers="matches reluc reluc_at_least"><i>X</i>, at least <i>n</i> times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="reluc_at_least_up_to"><i>X</i><code>{</code><i>n</i>{@code ,}<i>m</i><code>}?</code></th>
	* <td headers="matches reluc reluc_at_least_up_to"><i>X</i>, at least <i>n</i> but not more than <i>m</i> times</td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="poss">Possessive quantifiers</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="poss_once_or_not"><i>X</i>{@code ?+}</th>
	* <td headers="matches poss poss_once_or_not"><i>X</i>, once or not at all</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="poss_zero_or_more"><i>X</i>{@code *+}</th>
	* <td headers="matches poss poss_zero_or_more"><i>X</i>, zero or more times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="poss_one_or_more"><i>X</i>{@code ++}</th>
	* <td headers="matches poss poss_one_or_more"><i>X</i>, one or more times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="poss_exactly"><i>X</i><code>{</code><i>n</i><code>}+</code></th>
	* <td headers="matches poss poss_exactly"><i>X</i>, exactly <i>n</i> times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="poss_at_least"><i>X</i><code>{</code><i>n</i><code>,}+</code></th>
	* <td headers="matches poss poss_at_least"><i>X</i>, at least <i>n</i> times</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="poss_at_least_up_to"><i>X</i><code>{</code><i>n</i>{@code ,}<i>m</i><code>}+</code></th>
	* <td headers="matches poss poss_at_least_up_to"><i>X</i>, at least <i>n</i> but not more than <i>m</i> times</td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="logical">Logical operators</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="concat"><i>XY</i></th>
	* <td headers="matches logical concat"><i>X</i> followed by <i>Y</i></td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="alternate"><i>X</i>{@code \|}<i>Y</i></th>
	* <td headers="matches logical alternate">Either <i>X</i> or <i>Y</i></td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="group">{@code (}<i>X</i>{@code )}</th>
	* <td headers="matches logical group">X, as a <a href="#cg">capturing group</a></td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="backref">Back references</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="back_nth">{@code \}<i>n</i></th>
	* <td headers="matches backref back_nth">Whatever the <i>n</i><sup>th</sup>
	* <a href="#cg">capturing group</a> matched</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="back_named">{@code \}<i>k</i><<i>name</i>></th>
	* <td headers="matches backref back_named">Whatever the
	* <a href="#groupname">named-capturing group</a> "name" matched</td></tr>
	*
	* <tr><th colspan="2" style="padding-top:20px" id="quote">Quotation</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="quote_follow">{@code \}</th>
	* <td headers="matches quote quote_follow">Nothing, but quotes the following character</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="quote_begin">{@code \Q}</th>
	* <td headers="matches quote quote_begin">Nothing, but quotes all characters until {@code \E}</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="quote_end">{@code \E}</th>
	* <td headers="matches quote quote_end">Nothing, but ends quoting started by {@code \Q}</td></tr>
	* <!-- Metachars: !$()*+.<>?[\]^{\|} -->
	*
	* <tr><th colspan="2" style="padding-top:20px" id="special">Special constructs (named-capturing and non-capturing)</th></tr>
	*
	* <tr><th style="vertical-align:top; font-weight:normal" id="named_group"><code>(?<<a href="#groupname">name</a>></code><i>X</i>{@code )}</th>
	* <td headers="matches special named_group"><i>X</i>, as a named-capturing group</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="non_capture_group">{@code (?:}<i>X</i>{@code )}</th>
	* <td headers="matches special non_capture_group"><i>X</i>, as a non-capturing group</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="flags"><code>(?idmsuxU-idmsuxU) </code></th>
	* <td headers="matches special flags">Nothing, but turns match flags <a href="#CASE_INSENSITIVE">i</a>
	* <a href="#UNIX_LINES">d</a> <a href="#MULTILINE">m</a> <a href="#DOTALL">s</a>
	* <a href="#UNICODE_CASE">u</a> <a href="#COMMENTS">x</a> <a href="#UNICODE_CHARACTER_CLASS">U</a>
	* on - off</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="non_capture_group_flags"><code>(?idmsux-idmsux:</code><i>X</i>{@code )}  </th>
	* <td headers="matches special non_capture_group_flags"><i>X</i>, as a <a href="#cg">non-capturing group</a> with the
	* given flags <a href="#CASE_INSENSITIVE">i</a> <a href="#UNIX_LINES">d</a>
	* <a href="#MULTILINE">m</a> <a href="#DOTALL">s</a> <a href="#UNICODE_CASE">u</a >
	* <a href="#COMMENTS">x</a> on - off</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="pos_lookahead">{@code (?=}<i>X</i>{@code )}</th>
	* <td headers="matches special pos_lookahead"><i>X</i>, via zero-width positive lookahead</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="neg_lookahead">{@code (?!}<i>X</i>{@code )}</th>
	* <td headers="matches special neg_lookahead"><i>X</i>, via zero-width negative lookahead</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="pos_lookbehind">{@code (?<=}<i>X</i>{@code )}</th>
	* <td headers="matches special pos_lookbehind"><i>X</i>, via zero-width positive lookbehind</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="neg_lookbehind">{@code (?<!}<i>X</i>{@code )}</th>
	* <td headers="matches special neg_lookbehind"><i>X</i>, via zero-width negative lookbehind</td></tr>
	* <tr><th style="vertical-align:top; font-weight:normal" id="indep_non_capture_group">{@code (?>}<i>X</i>{@code )}</th>
	* <td headers="matches special indep_non_capture_group"><i>X</i>, as an independent, non-capturing group</td></tr>
	*
	* </tbody>
	* </table>
	*
	* <hr>
	*
	*
	* <h3><a id="bs">Backslashes, escapes, and quoting</a></h3>
	*
	* <p> The backslash character ({@code '\'}) serves to introduce escaped
	* constructs, as defined in the table above, as well as to quote characters
	* that otherwise would be interpreted as unescaped constructs. Thus the
	* expression {@code \\} matches a single backslash and <code>\{</code> matches a
	* left brace.
	*
	* <p> It is an error to use a backslash prior to any alphabetic character that
	* does not denote an escaped construct; these are reserved for future
	* extensions to the regular-expression language. A backslash may be used
	* prior to a non-alphabetic character regardless of whether that character is
	* part of an unescaped construct.
	*
	* <p> Backslashes within string literals in Java source code are interpreted
	* as required by
	* <cite>The Java™ Language Specification</cite>
	* as either Unicode escapes (section 3.3) or other character escapes (section 3.10.6)
	* It is therefore necessary to double backslashes in string
	* literals that represent regular expressions to protect them from
	* interpretation by the Java bytecode compiler. The string literal
	* <code>"\b"</code>, for example, matches a single backspace character when
	* interpreted as a regular expression, while {@code "\\b"} matches a
	* word boundary. The string literal {@code "$hello$"} is illegal
	* and leads to a compile-time error; in order to match the string
	* {@code (hello)} the string literal {@code "\$hello\$"}
	* must be used.
	*
	* <h3><a id="cc">Character Classes</a></h3>
	*
	* <p> Character classes may appear within other character classes, and
	* may be composed by the union operator (implicit) and the intersection
	* operator ({@code &&}).
	* The union operator denotes a class that contains every character that is
	* in at least one of its operand classes. The intersection operator
	* denotes a class that contains every character that is in both of its
	* operand classes.
	*
	* <p> The precedence of character-class operators is as follows, from
	* highest to lowest:
	*
	* <table class="striped" style="margin-left: 2em;">
	* <caption style="display:none">Precedence of character class operators.</caption>
	* <thead>
	* <tr><th scope="col">Precedence<th scope="col">Name<th scope="col">Example
	* </thead>
	* <tbody>
	* <tr><th scope="row">1</th>
	* <td>Literal escape    </td>
	* <td>{@code \x}</td></tr>
	* <tr><th scope="row">2</th>
	* <td>Grouping</td>
	* <td>{@code [...]}</td></tr>
	* <tr><th scope="row">3</th>
	* <td>Range</td>
	* <td>{@code a-z}</td></tr>
	* <tr><th scope="row">4</th>
	* <td>Union</td>
	* <td>{@code [a-e][i-u]}</td></tr>
	* <tr><th scope="row">5</th>
	* <td>Intersection</td>
	* <td>{@code [a-z&&[aeiou]]}</td></tr>
	* </tbody>
	* </table>
	*
	* <p> Note that a different set of metacharacters are in effect inside
	* a character class than outside a character class. For instance, the
	* regular expression {@code .} loses its special meaning inside a
	* character class, while the expression {@code -} becomes a range
	* forming metacharacter.
	*
	* <h3><a id="lt">Line terminators</a></h3>
	*
	* <p> A <i>line terminator</i> is a one- or two-character sequence that marks
	* the end of a line of the input character sequence. The following are
	* recognized as line terminators:
	*
	* <ul>
	*
	* <li> A newline (line feed) character ({@code '\n'}),
	*
	* <li> A carriage-return character followed immediately by a newline
	* character ({@code "\r\n"}),
	*
	* <li> A standalone carriage-return character ({@code '\r'}),
	*
	* <li> A next-line character (<code>'\u0085'</code>),
	*
	* <li> A line-separator character (<code>'\u2028'</code>), or
	*
	* <li> A paragraph-separator character (<code>'\u2029'</code>).
	*
	* </ul>
	* <p>If {@link #UNIX_LINES} mode is activated, then the only line terminators
	* recognized are newline characters.
	*
	* <p> The regular expression {@code .} matches any character except a line
	* terminator unless the {@link #DOTALL} flag is specified.
	*
	* <p> By default, the regular expressions {@code ^} and {@code $} ignore
	* line terminators and only match at the beginning and the end, respectively,
	* of the entire input sequence. If {@link #MULTILINE} mode is activated then
	* {@code ^} matches at the beginning of input and after any line terminator
	* except at the end of input. When in {@link #MULTILINE} mode {@code $}
	* matches just before a line terminator or the end of the input sequence.
	*
	* <h3><a id="cg">Groups and capturing</a></h3>
	*
	* <h4><a id="gnumber">Group number</a></h4>
	* <p> Capturing groups are numbered by counting their opening parentheses from
	* left to right. In the expression {@code ((A)(B(C)))}, for example, there
	* are four such groups: </p>
	*
	* <ol style="margin-left:2em;">
	* <li> {@code ((A)(B(C)))}
	* <li> {@code (A)}
	* <li> {@code (B(C))}
	* <li> {@code (C)}
	* </ol>
	*
	* <p> Group zero always stands for the entire expression.
	*
	* <p> Capturing groups are so named because, during a match, each subsequence
	* of the input sequence that matches such a group is saved. The captured
	* subsequence may be used later in the expression, via a back reference, and
	* may also be retrieved from the matcher once the match operation is complete.
	*
	* <h4><a id="groupname">Group name</a></h4>
	* <p>A capturing group can also be assigned a "name", a {@code named-capturing group},
	* and then be back-referenced later by the "name". Group names are composed of
	* the following characters. The first character must be a {@code letter}.
	*
	* <ul>
	* <li> The uppercase letters {@code 'A'} through {@code 'Z'}
	* (<code>'\u0041'</code> through <code>'\u005a'</code>),
	* <li> The lowercase letters {@code 'a'} through {@code 'z'}
	* (<code>'\u0061'</code> through <code>'\u007a'</code>),
	* <li> The digits {@code '0'} through {@code '9'}
	* (<code>'\u0030'</code> through <code>'\u0039'</code>),
	* </ul>
	*
	* <p> A {@code named-capturing group} is still numbered as described in
	* <a href="#gnumber">Group number</a>.
	*
	* <p> The captured input associated with a group is always the subsequence
	* that the group most recently matched. If a group is evaluated a second time
	* because of quantification then its previously-captured value, if any, will
	* be retained if the second evaluation fails. Matching the string
	* {@code "aba"} against the expression {@code (a(b)?)+}, for example, leaves
	* group two set to {@code "b"}. All captured input is discarded at the
	* beginning of each match.
	*
	* <p> Groups beginning with {@code (?} are either pure, <i>non-capturing</i> groups
	* that do not capture text and do not count towards the group total, or
	* <i>named-capturing</i> group.
	*
	* <h3> Unicode support </h3>
	*
	* <p> This class is in conformance with Level 1 of <a
	* href="http://www.unicode.org/reports/tr18/"><i>Unicode Technical
	* Standard #18: Unicode Regular Expression</i></a>, plus RL2.1
	* Canonical Equivalents.
	* <p>
	* <b>Unicode escape sequences</b> such as <code>\u2014</code> in Java source code
	* are processed as described in section 3.3 of
	* <cite>The Java™ Language Specification</cite>.
	* Such escape sequences are also implemented directly by the regular-expression
	* parser so that Unicode escapes can be used in expressions that are read from
	* files or from the keyboard. Thus the strings <code>"\u2014"</code> and
	* {@code "\\u2014"}, while not equal, compile into the same pattern, which
	* matches the character with hexadecimal value {@code 0x2014}.
	* <p>
	* A Unicode character can also be represented by using its <b>Hex notation</b>
	* (hexadecimal code point value) directly as described in construct
	* <code>\x{...}</code>, for example a supplementary character U+2011F can be
	* specified as <code>\x{2011F}</code>, instead of two consecutive Unicode escape
	* sequences of the surrogate pair <code>\uD840</code><code>\uDD1F</code>.
	* <p>
	* <b>Unicode character names</b> are supported by the named character construct
	* <code>\N{</code>...<code>}</code>, for example, <code>\N{WHITE SMILING FACE}</code>
	* specifies character <code>\u263A</code>. The character names supported
	* by this class are the valid Unicode character names matched by
	* {@link java.lang.Character#codePointOf(String) Character.codePointOf(name)}.
	* <p>
	* <a href="http://www.unicode.org/reports/tr18/#Default_Grapheme_Clusters">
	* <b>Unicode extended grapheme clusters</b></a> are supported by the grapheme
	* cluster matcher {@code \X} and the corresponding boundary matcher {@code \b{g}}.
	* <p>
	* Unicode scripts, blocks, categories and binary properties are written with
	* the {@code \p} and {@code \P} constructs as in Perl.
	* <code>\p{</code><i>prop</i><code>}</code> matches if
	* the input has the property <i>prop</i>, while <code>\P{</code><i>prop</i><code>}</code>
	* does not match if the input has that property.
	* <p>
	* Scripts, blocks, categories and binary properties can be used both inside
	* and outside of a character class.
	*
	* <p>
	* <b><a id="usc">Scripts</a></b> are specified either with the prefix {@code Is}, as in
	* {@code IsHiragana}, or by using the {@code script} keyword (or its short
	* form {@code sc}) as in {@code script=Hiragana} or {@code sc=Hiragana}.
	* <p>
	* The script names supported by {@code Pattern} are the valid script names
	* accepted and defined by
	* {@link java.lang.Character.UnicodeScript#forName(String) UnicodeScript.forName}.
	*
	* <p>
	* <b><a id="ubc">Blocks</a></b> are specified with the prefix {@code In}, as in
	* {@code InMongolian}, or by using the keyword {@code block} (or its short
	* form {@code blk}) as in {@code block=Mongolian} or {@code blk=Mongolian}.
	* <p>
	* The block names supported by {@code Pattern} are the valid block names
	* accepted and defined by
	* {@link java.lang.Character.UnicodeBlock#forName(String) UnicodeBlock.forName}.
	* <p>
	*
	* <b><a id="ucc">Categories</a></b> may be specified with the optional prefix {@code Is}:
	* Both {@code \p{L}} and {@code \p{IsL}} denote the category of Unicode
	* letters. Same as scripts and blocks, categories can also be specified
	* by using the keyword {@code general_category} (or its short form
	* {@code gc}) as in {@code general_category=Lu} or {@code gc=Lu}.
	* <p>
	* The supported categories are those of
	* <a href="http://www.unicode.org/unicode/standard/standard.html">
	* <i>The Unicode Standard</i></a> in the version specified by the
	* {@link java.lang.Character Character} class. The category names are those
	* defined in the Standard, both normative and informative.
	* <p>
	*
	* <b><a id="ubpc">Binary properties</a></b> are specified with the prefix {@code Is}, as in
	* {@code IsAlphabetic}. The supported binary properties by {@code Pattern}
	* are
	* <ul>
	* <li> Alphabetic
	* <li> Ideographic
	* <li> Letter
	* <li> Lowercase
	* <li> Uppercase
	* <li> Titlecase
	* <li> Punctuation
	* <Li> Control
	* <li> White_Space
	* <li> Digit
	* <li> Hex_Digit
	* <li> Join_Control
	* <li> Noncharacter_Code_Point
	* <li> Assigned
	* </ul>
	* <p>
	* The following <b>Predefined Character classes</b> and <b>POSIX character classes</b>
	* are in conformance with the recommendation of <i>Annex C: Compatibility Properties</i>
	* of <a href="http://www.unicode.org/reports/tr18/"><i>Unicode Regular Expression
	* </i></a>, when {@link #UNICODE_CHARACTER_CLASS} flag is specified.
	*
	* <table class="striped">
	* <caption style="display:none">predefined and posix character classes in Unicode mode</caption>
	* <thead>
	* <tr>
	* <th scope="col" id="predef_classes">Classes</th>
	* <th scope="col" id="predef_matches">Matches</th>
	* </tr>
	* </thead>
	* <tbody>
	* <tr><th scope="row">{@code \p{Lower}}</th>
	* <td>A lowercase character:{@code \p{IsLowercase}}</td></tr>
	* <tr><th scope="row">{@code \p{Upper}}</th>
	* <td>An uppercase character:{@code \p{IsUppercase}}</td></tr>
	* <tr><th scope="row">{@code \p{ASCII}}</th>
	* <td>All ASCII:{@code [\x00-\x7F]}</td></tr>
	* <tr><th scope="row">{@code \p{Alpha}}</th>
	* <td>An alphabetic character:{@code \p{IsAlphabetic}}</td></tr>
	* <tr><th scope="row">{@code \p{Digit}}</th>
	* <td>A decimal digit character:{@code \p{IsDigit}}</td></tr>
	* <tr><th scope="row">{@code \p{Alnum}}</th>
	* <td>An alphanumeric character:{@code [\p{IsAlphabetic}\p{IsDigit}]}</td></tr>
	* <tr><th scope="row">{@code \p{Punct}}</th>
	* <td>A punctuation character:{@code \p{IsPunctuation}}</td></tr>
	* <tr><th scope="row">{@code \p{Graph}}</th>
	* <td>A visible character: {@code [^\p{IsWhite_Space}\p{gc=Cc}\p{gc=Cs}\p{gc=Cn}]}</td></tr>
	* <tr><th scope="row">{@code \p{Print}}</th>
	* <td>A printable character: {@code [\p{Graph}\p{Blank}&&[^\p{Cntrl}]]}</td></tr>
	* <tr><th scope="row">{@code \p{Blank}}</th>
	* <td>A space or a tab: {@code [\p{IsWhite_Space}&&[^\p{gc=Zl}\p{gc=Zp}\x0a\x0b\x0c\x0d\x85]]}</td></tr>
	* <tr><th scope="row">{@code \p{Cntrl}}</th>
	* <td>A control character: {@code \p{gc=Cc}}</td></tr>
	* <tr><th scope="row">{@code \p{XDigit}}</th>
	* <td>A hexadecimal digit: {@code [\p{gc=Nd}\p{IsHex_Digit}]}</td></tr>
	* <tr><th scope="row">{@code \p{Space}}</th>
	* <td>A whitespace character:{@code \p{IsWhite_Space}}</td></tr>
	* <tr><th scope="row">{@code \d}</th>
	* <td>A digit: {@code \p{IsDigit}}</td></tr>
	* <tr><th scope="row">{@code \D}</th>
	* <td>A non-digit: {@code [^\d]}</td></tr>
	* <tr><th scope="row">{@code \s}</th>
	* <td>A whitespace character: {@code \p{IsWhite_Space}}</td></tr>
	* <tr><th scope="row">{@code \S}</th>
	* <td>A non-whitespace character: {@code [^\s]}</td></tr>
	* <tr><th scope="row">{@code \w}</th>
	* <td>A word character: {@code [\p{Alpha}\p{gc=Mn}\p{gc=Me}\p{gc=Mc}\p{Digit}\p{gc=Pc}\p{IsJoin_Control}]}</td></tr>
	* <tr><th scope="row">{@code \W}</th>
	* <td>A non-word character: {@code [^\w]}</td></tr>
	* </tbody>
	* </table>
	* <p>
	* <a id="jcc">
	* Categories that behave like the java.lang.Character
	* boolean is<i>methodname</i> methods (except for the deprecated ones) are
	* available through the same <code>\p{</code><i>prop</i><code>}</code> syntax where
	* the specified property has the name <code>java<i>methodname</i></code></a>.
	*
	* <h3> Comparison to Perl 5 </h3>
	*
	* <p>The {@code Pattern} engine performs traditional NFA-based matching
	* with ordered alternation as occurs in Perl 5.
	*
	* <p> Perl constructs not supported by this class: </p>
	*
	* <ul>
	* <li><p> The backreference constructs, <code>\g{</code><i>n</i><code>}</code> for
	* the <i>n</i><sup>th</sup><a href="#cg">capturing group</a> and
	* <code>\g{</code><i>name</i><code>}</code> for
	* <a href="#groupname">named-capturing group</a>.
	* </p></li>
	*
	* <li><p> The conditional constructs
	* {@code (?(}<i>condition</i>{@code )}<i>X</i>{@code )} and
	* {@code (?(}<i>condition</i>{@code )}<i>X</i>{@code \|}<i>Y</i>{@code )},
	* </p></li>
	*
	* <li><p> The embedded code constructs <code>(?{</code><i>code</i><code>})</code>
	* and <code>(??{</code><i>code</i><code>})</code>,</p></li>
	*
	* <li><p> The embedded comment syntax {@code (?#comment)}, and </p></li>
	*
	* <li><p> The preprocessing operations {@code \l} <code>\u</code>,
	* {@code \L}, and {@code \U}. </p></li>
	*
	* </ul>
	*
	* <p> Constructs supported by this class but not by Perl: </p>
	*
	* <ul>
	*
	* <li><p> Character-class union and intersection as described
	* <a href="#cc">above</a>.</p></li>
	*
	* </ul>
	*
	* <p> Notable differences from Perl: </p>
	*
	* <ul>
	*
	* <li><p> In Perl, {@code \1} through {@code \9} are always interpreted
	* as back references; a backslash-escaped number greater than {@code 9} is
	* treated as a back reference if at least that many subexpressions exist,
	* otherwise it is interpreted, if possible, as an octal escape. In this
	* class octal escapes must always begin with a zero. In this class,
	* {@code \1} through {@code \9} are always interpreted as back
	* references, and a larger number is accepted as a back reference if at
	* least that many subexpressions exist at that point in the regular
	* expression, otherwise the parser will drop digits until the number is
	* smaller or equal to the existing number of groups or it is one digit.
	* </p></li>
	*
	* <li><p> Perl uses the {@code g} flag to request a match that resumes
	* where the last match left off. This functionality is provided implicitly
	* by the {@link Matcher} class: Repeated invocations of the {@link
	* Matcher#find find} method will resume where the last match left off,
	* unless the matcher is reset. </p></li>
	*
	* <li><p> In Perl, embedded flags at the top level of an expression affect
	* the whole expression. In this class, embedded flags always take effect
	* at the point at which they appear, whether they are at the top level or
	* within a group; in the latter case, flags are restored at the end of the
	* group just as in Perl. </p></li>
	*
	* </ul>
	*
	*
	* <p> For a more precise description of the behavior of regular expression
	* constructs, please see <a href="http://www.oreilly.com/catalog/regex3/">
	* <i>Mastering Regular Expressions, 3nd Edition</i>, Jeffrey E. F. Friedl,
	* O'Reilly and Associates, 2006.</a>
	* </p>
	*
	* @see java.lang.String#split(String, int)
	* @see java.lang.String#split(String)
	*
	* @author Mike McCloskey
	* @author Mark Reinhold
	* @author JSR-51 Expert Group
	* @since 1.4
	* @spec JSR-51
	*/

	public final class Pattern
	implements java.io.Serializable
	{

	/**
	* Regular expression modifier values. Instead of being passed as
	* arguments, they can also be passed as inline modifiers.
	* For example, the following statements have the same effect.
	* <pre>
	* Pattern p1 = Pattern.compile("abc", Pattern.CASE_INSENSITIVE\|Pattern.MULTILINE);
	* Pattern p2 = Pattern.compile("(?im)abc", 0);
	* </pre>
	*/

	/**
	* Enables Unix lines mode.
	*
	* <p> In this mode, only the {@code '\n'} line terminator is recognized
	* in the behavior of {@code .}, {@code ^}, and {@code $}.
	*
	* <p> Unix lines mode can also be enabled via the embedded flag
	* expression {@code (?d)}.
	*/
	public static final int UNIX_LINES = 0x01;

	/**
	* Enables case-insensitive matching.
	*
	* <p> By default, case-insensitive matching assumes that only characters
	* in the US-ASCII charset are being matched. Unicode-aware
	* case-insensitive matching can be enabled by specifying the {@link
	* #UNICODE_CASE} flag in conjunction with this flag.
	*
	* <p> Case-insensitive matching can also be enabled via the embedded flag
	* expression {@code (?i)}.
	*
	* <p> Specifying this flag may impose a slight performance penalty. </p>
	*/
	public static final int CASE_INSENSITIVE = 0x02;

	/**
	* Permits whitespace and comments in pattern.
	*
	* <p> In this mode, whitespace is ignored, and embedded comments starting
	* with {@code #} are ignored until the end of a line.
	*
	* <p> Comments mode can also be enabled via the embedded flag
	* expression {@code (?x)}.
	*/
	public static final int COMMENTS = 0x04;

	/**
	* Enables multiline mode.
	*
	* <p> In multiline mode the expressions {@code ^} and {@code $} match
	* just after or just before, respectively, a line terminator or the end of
	* the input sequence. By default these expressions only match at the
	* beginning and the end of the entire input sequence.
	*
	* <p> Multiline mode can also be enabled via the embedded flag
	* expression {@code (?m)}. </p>
	*/
	public static final int MULTILINE = 0x08;

	/**
	* Enables literal parsing of the pattern.
	*
	* <p> When this flag is specified then the input string that specifies
	* the pattern is treated as a sequence of literal characters.
	* Metacharacters or escape sequences in the input sequence will be
	* given no special meaning.
	*
	* <p>The flags CASE_INSENSITIVE and UNICODE_CASE retain their impact on
	* matching when used in conjunction with this flag. The other flags
	* become superfluous.
	*
	* <p> There is no embedded flag character for enabling literal parsing.
	* @since 1.5
	*/
	public static final int LITERAL = 0x10;

	/**
	* Enables dotall mode.
	*
	* <p> In dotall mode, the expression {@code .} matches any character,
	* including a line terminator. By default this expression does not match
	* line terminators.
	*
	* <p> Dotall mode can also be enabled via the embedded flag
	* expression {@code (?s)}. (The {@code s} is a mnemonic for
	* "single-line" mode, which is what this is called in Perl.) </p>
	*/
	public static final int DOTALL = 0x20;

	/**
	* Enables Unicode-aware case folding.
	*
	* <p> When this flag is specified then case-insensitive matching, when
	* enabled by the {@link #CASE_INSENSITIVE} flag, is done in a manner
	* consistent with the Unicode Standard. By default, case-insensitive
	* matching assumes that only characters in the US-ASCII charset are being
	* matched.
	*
	* <p> Unicode-aware case folding can also be enabled via the embedded flag
	* expression {@code (?u)}.
	*
	* <p> Specifying this flag may impose a performance penalty. </p>
	*/
	public static final int UNICODE_CASE = 0x40;

	/**
	* Enables canonical equivalence.
	*
	* <p> When this flag is specified then two characters will be considered
	* to match if, and only if, their full canonical decompositions match.
	* The expression <code>"a\u030A"</code>, for example, will match the
	* string <code>"\u00E5"</code> when this flag is specified. By default,
	* matching does not take canonical equivalence into account.
	*
	* <p> There is no embedded flag character for enabling canonical
	* equivalence.
	*
	* <p> Specifying this flag may impose a performance penalty. </p>
	*/
	public static final int CANON_EQ = 0x80;

	/**
	* Enables the Unicode version of <i>Predefined character classes</i> and
	* <i>POSIX character classes</i>.
	*
	* <p> When this flag is specified then the (US-ASCII only)
	* <i>Predefined character classes</i> and <i>POSIX character classes</i>
	* are in conformance with
	* <a href="http://www.unicode.org/reports/tr18/"><i>Unicode Technical
	* Standard #18: Unicode Regular Expression</i></a>
	* <i>Annex C: Compatibility Properties</i>.
	* <p>
	* The UNICODE_CHARACTER_CLASS mode can also be enabled via the embedded
	* flag expression {@code (?U)}.
	* <p>
	* The flag implies UNICODE_CASE, that is, it enables Unicode-aware case
	* folding.
	* <p>
	* Specifying this flag may impose a performance penalty. </p>
	* @since 1.7
	*/
	public static final int UNICODE_CHARACTER_CLASS = 0x100;

	/**
	* Contains all possible flags for compile(regex, flags).
	*/
	private static final int ALL_FLAGS = CASE_INSENSITIVE \| MULTILINE \|
	DOTALL \| UNICODE_CASE \| CANON_EQ \| UNIX_LINES \| LITERAL \|
	UNICODE_CHARACTER_CLASS \| COMMENTS;

	/* Pattern has only two serialized components: The pattern string
	* and the flags, which are all that is needed to recompile the pattern
	* when it is deserialized.
	*/

	/** use serialVersionUID from Merlin b59 for interoperability */
	private static final long serialVersionUID = 5073258162644648461L;

	/**
	* The original regular-expression pattern string.
	*
	* @serial
	*/
	private String pattern;

	/**
	* The original pattern flags.
	*
	* @serial
	*/
	private int flags;

	/**
	* The temporary pattern flags used during compiling. The flags might be turn
	* on and off by embedded flag.
	*/
	private transient int flags0;

	/**
	* Boolean indicating this Pattern is compiled; this is necessary in order
	* to lazily compile deserialized Patterns.
	*/
	private transient volatile boolean compiled;

	/**
	* The normalized pattern string.
	*/
	private transient String normalizedPattern;

	/**
	* The starting point of state machine for the find operation. This allows
	* a match to start anywhere in the input.
	*/
	transient Node root;

	/**
	* The root of object tree for a match operation. The pattern is matched
	* at the beginning. This may include a find that uses BnM or a First
	* node.
	*/
	transient Node matchRoot;

	/**
	* Temporary storage used by parsing pattern slice.
	*/
	transient int[] buffer;

	/**
	* A temporary storage used for predicate for double return.
	*/
	transient CharPredicate predicate;

	/**
	* Map the "name" of the "named capturing group" to its group id
	* node.
	*/
	transient volatile Map<String, Integer> namedGroups;

	/**
	* Temporary storage used while parsing group references.
	*/
	transient GroupHead[] groupNodes;

	/**
	* Temporary storage used to store the top level closure nodes.
	*/
	transient List<Node> topClosureNodes;

	/**
	* The number of top greedy closure nodes in this Pattern. Used by
	* matchers to allocate storage needed for a IntHashSet to keep the
	* beginning pos {@code i} of all failed match.
	*/
	transient int localTCNCount;

	/*
	* Turn off the stop-exponential-backtracking optimization if there
	* is a group ref in the pattern.
	*/
	transient boolean hasGroupRef;

	/**
	* Temporary null terminated code point array used by pattern compiling.
	*/
	private transient int[] temp;

	/**
	* The number of capturing groups in this Pattern. Used by matchers to
	* allocate storage needed to perform a match.
	*/
	transient int capturingGroupCount;

	/**
	* The local variable count used by parsing tree. Used by matchers to
	* allocate storage needed to perform a match.
	*/
	transient int localCount;

	/**
	* Index into the pattern string that keeps track of how much has been
	* parsed.
	*/
	private transient int cursor;

	/**
	* Holds the length of the pattern string.
	*/
	private transient int patternLength;

	/**
	* If the Start node might possibly match supplementary characters.
	* It is set to true during compiling if
	* (1) There is supplementary char in pattern, or
	* (2) There is complement node of a "family" CharProperty
	*/
	private transient boolean hasSupplementary;

	/**
	* Compiles the given regular expression into a pattern.
	*
	* @param regex
	* The expression to be compiled
	* @return the given regular expression compiled into a pattern
	* @throws PatternSyntaxException
	* If the expression's syntax is invalid
	*/
	public static Pattern compile(String regex) {
	return new Pattern(regex, 0);
	}

	/**
	* Compiles the given regular expression into a pattern with the given
	* flags.
	*
	* @param regex
	* The expression to be compiled
	*
	* @param flags
	* Match flags, a bit mask that may include
	* {@link #CASE_INSENSITIVE}, {@link #MULTILINE}, {@link #DOTALL},
	* {@link #UNICODE_CASE}, {@link #CANON_EQ}, {@link #UNIX_LINES},
	* {@link #LITERAL}, {@link #UNICODE_CHARACTER_CLASS}
	* and {@link #COMMENTS}
	*
	* @return the given regular expression compiled into a pattern with the given flags
	* @throws IllegalArgumentException
	* If bit values other than those corresponding to the defined
	* match flags are set in {@code flags}
	*
	* @throws PatternSyntaxException
	* If the expression's syntax is invalid
	*/
	public static Pattern compile(String regex, int flags) {
	return new Pattern(regex, flags);
	}

	/**
	* Returns the regular expression from which this pattern was compiled.
	*
	* @return The source of this pattern
	*/
	public String pattern() {
	return pattern;
	}

	/**
	* <p>Returns the string representation of this pattern. This
	* is the regular expression from which this pattern was
	* compiled.</p>
	*
	* @return The string representation of this pattern
	* @since 1.5
	*/
	public String toString() {
	return pattern;
	}

	/**
	* Creates a matcher that will match the given input against this pattern.
	*
	* @param input
	* The character sequence to be matched
	*
	* @return A new matcher for this pattern
	*/
	public Matcher matcher(CharSequence input) {
	if (!compiled) {
	synchronized(this) {
	if (!compiled)
	compile();
	}
	}
	Matcher m = new Matcher(this, input);
	return m;
	}

	/**
	* Returns this pattern's match flags.
	*
	* @return The match flags specified when this pattern was compiled
	*/
	public int flags() {
	return flags0;
	}

	/**
	* Compiles the given regular expression and attempts to match the given
	* input against it.
	*
	* <p> An invocation of this convenience method of the form
	*
	* <blockquote><pre>
	* Pattern.matches(regex, input);</pre></blockquote>
	*
	* behaves in exactly the same way as the expression
	*
	* <blockquote><pre>
	* Pattern.compile(regex).matcher(input).matches()</pre></blockquote>
	*
	* <p> If a pattern is to be used multiple times, compiling it once and reusing
	* it will be more efficient than invoking this method each time. </p>
	*
	* @param regex
	* The expression to be compiled
	*
	* @param input
	* The character sequence to be matched
	* @return whether or not the regular expression matches on the input
	* @throws PatternSyntaxException
	* If the expression's syntax is invalid
	*/
	public static boolean matches(String regex, CharSequence input) {
	Pattern p = Pattern.compile(regex);
	Matcher m = p.matcher(input);
	return m.matches();
	}

	/**
	* Splits the given input sequence around matches of this pattern.
	*
	* <p> The array returned by this method contains each substring of the
	* input sequence that is terminated by another subsequence that matches
	* this pattern or is terminated by the end of the input sequence. The
	* substrings in the array are in the order in which they occur in the
	* input. If this pattern does not match any subsequence of the input then
	* the resulting array has just one element, namely the input sequence in
	* string form.
	*
	* <p> When there is a positive-width match at the beginning of the input
	* sequence then an empty leading substring is included at the beginning
	* of the resulting array. A zero-width match at the beginning however
	* never produces such empty leading substring.
	*
	* <p> The {@code limit} parameter controls the number of times the
	* pattern is applied and therefore affects the length of the resulting
	* array.
	* <ul>
	* <li><p>
	* If the <i>limit</i> is positive then the pattern will be applied
	* at most <i>limit</i> - 1 times, the array's length will be
	* no greater than <i>limit</i>, and the array's last entry will contain
	* all input beyond the last matched delimiter.</p></li>
	*
	* <li><p>
	* If the <i>limit</i> is zero then the pattern will be applied as
	* many times as possible, the array can have any length, and trailing
	* empty strings will be discarded.</p></li>
	*
	* <li><p>
	* If the <i>limit</i> is negative then the pattern will be applied
	* as many times as possible and the array can have any length.</p></li>
	* </ul>
	*
	* <p> The input {@code "boo:and:foo"}, for example, yields the following
	* results with these parameters:
	*
	* <table class="plain" style="margin-left:2em;">
	* <caption style="display:none">Split example showing regex, limit, and result</caption>
	* <thead>
	* <tr>
	* <th scope="col">Regex</th>
	* <th scope="col">Limit</th>
	* <th scope="col">Result</th>
	* </tr>
	* </thead>
	* <tbody>
	* <tr><th scope="row" rowspan="3" style="font-weight:normal">:</th>
	* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">2</th>
	* <td>{@code { "boo", "and:foo" }}</td></tr>
	* <tr><!-- : -->
	* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">5</th>
	* <td>{@code { "boo", "and", "foo" }}</td></tr>
	* <tr><!-- : -->
	* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">-2</th>
	* <td>{@code { "boo", "and", "foo" }}</td></tr>
	* <tr><th scope="row" rowspan="3" style="font-weight:normal">o</th>
	* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">5</th>
	* <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
	* <tr><!-- o -->
	* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">-2</th>
	* <td>{@code { "b", "", ":and:f", "", "" }}</td></tr>
	* <tr><!-- o -->
	* <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">0</th>
	* <td>{@code { "b", "", ":and:f" }}</td></tr>
	* </tbody>
	* </table>
	*
	* @param input
	* The character sequence to be split
	*
	* @param limit
	* The result threshold, as described above
	*
	* @return The array of strings computed by splitting the input
	* around matches of this pattern
	*/
	public String[] split(CharSequence input, int limit) {
	int index = 0;
	boolean matchLimited = limit > 0;
	ArrayList<String> matchList = new ArrayList<>();
	Matcher m = matcher(input);

	// Add segments before each match found
	while(m.find()) {
	if (!matchLimited \|\| matchList.size() < limit - 1) {
	if (index == 0 && index == m.start() && m.start() == m.end()) {
	// no empty leading substring included for zero-width match
	// at the beginning of the input char sequence.
	continue;
	}
	String match = input.subSequence(index, m.start()).toString();
	matchList.add(match);
	index = m.end();
	} else if (matchList.size() == limit - 1) { // last one
	String match = input.subSequence(index,
	input.length()).toString();
	matchList.add(match);
	index = m.end();
	}
	}

	// If no match was found, return this
	if (index == 0)
	return new String[] {input.toString()};

	// Add remaining segment
	if (!matchLimited \|\| matchList.size() < limit)
	matchList.add(input.subSequence(index, input.length()).toString());

	// Construct result
	int resultSize = matchList.size();
	if (limit == 0)
	while (resultSize > 0 && matchList.get(resultSize-1).equals(""))
	resultSize--;
	String[] result = new String[resultSize];
	return matchList.subList(0, resultSize).toArray(result);
	}

	/**
	* Splits the given input sequence around matches of this pattern.
	*
	* <p> This method works as if by invoking the two-argument {@link
	* #split(java.lang.CharSequence, int) split} method with the given input
	* sequence and a limit argument of zero. Trailing empty strings are
	* therefore not included in the resulting array. </p>
	*
	* <p> The input {@code "boo:and:foo"}, for example, yields the following
	* results with these expressions:
	*
	* <table class="plain" style="margin-left:2em">
	* <caption style="display:none">Split examples showing regex and result</caption>
	* <thead>
	* <tr>
	* <th scope="col">Regex</th>
	* <th scope="col">Result</th>
	* </tr>
	* </thead>
	* <tbody>
	* <tr><th scope="row" style="text-weight:normal">:</th>
	* <td>{@code { "boo", "and", "foo" }}</td></tr>
	* <tr><th scope="row" style="text-weight:normal">o</th>
	* <td>{@code { "b", "", ":and:f" }}</td></tr>
	* </tbody>
	* </table>
	*
	*
	* @param input
	* The character sequence to be split
	*
	* @return The array of strings computed by splitting the input
	* around matches of this pattern
	*/
	public String[] split(CharSequence input) {
	return split(input, 0);
	}

	/**
	* Returns a literal pattern {@code String} for the specified
	* {@code String}.
	*
	* <p>This method produces a {@code String} that can be used to
	* create a {@code Pattern} that would match the string
	* {@code s} as if it were a literal pattern.</p> Metacharacters
	* or escape sequences in the input sequence will be given no special
	* meaning.
	*
	* @param s The string to be literalized
	* @return A literal string replacement
	* @since 1.5
	*/
	public static String quote(String s) {
	int slashEIndex = s.indexOf("\\E");
	if (slashEIndex == -1)
	return "\\Q" + s + "\\E";

	int lenHint = s.length();
	lenHint = (lenHint < Integer.MAX_VALUE - 8 - lenHint) ?
	(lenHint << 1) : (Integer.MAX_VALUE - 8);

	StringBuilder sb = new StringBuilder(lenHint);
	sb.append("\\Q");
	int current = 0;
	do {
	sb.append(s, current, slashEIndex)
	.append("\\E\\\\E\\Q");
	current = slashEIndex + 2;
	} while ((slashEIndex = s.indexOf("\\E", current)) != -1);

	return sb.append(s, current, s.length())
	.append("\\E")
	.toString();
	}

	/**
	* Recompile the Pattern instance from a stream. The original pattern
	* string is read in and the object tree is recompiled from it.
	*/
	private void readObject(java.io.ObjectInputStream s)
	throws java.io.IOException, ClassNotFoundException {

	// Read in all fields
	s.defaultReadObject();

	// reset the flags
	flags0 = flags;

	// Initialize counts
	capturingGroupCount = 1;
	localCount = 0;
	localTCNCount = 0;

	// if length > 0, the Pattern is lazily compiled
	if (pattern.length() == 0) {
	root = new Start(lastAccept);
	matchRoot = lastAccept;
	compiled = true;
	}
	}

	/**
	* This private constructor is used to create all Patterns. The pattern
	* string and match flags are all that is needed to completely describe
	* a Pattern. An empty pattern string results in an object tree with
	* only a Start node and a LastNode node.
	*/
	private Pattern(String p, int f) {
	if ((f & ~ALL_FLAGS) != 0) {
	throw new IllegalArgumentException("Unknown flag 0x"
	+ Integer.toHexString(f));
	}
	pattern = p;
	flags = f;

	// to use UNICODE_CASE if UNICODE_CHARACTER_CLASS present
	if ((flags & UNICODE_CHARACTER_CLASS) != 0)
	flags \|= UNICODE_CASE;

	// 'flags' for compiling
	flags0 = flags;

	// Reset group index count
	capturingGroupCount = 1;
	localCount = 0;
	localTCNCount = 0;

	if (pattern.length() > 0) {
	compile();
	} else {
	root = new Start(lastAccept);
	matchRoot = lastAccept;
	}
	}

	/**
	* The pattern is converted to normalized form ({@link
	* java.text.Normalizer.Form.NFC NFC}, canonical decomposition,
	* followed by canonical composition for the character class
	* part, and {@link java.text.Normalizer.Form.NFD NFD},
	* canonical decomposition) for the rest), and then a pure
	* group is constructed to match canonical equivalences of the
	* characters.
	*/
	private static String normalize(String pattern) {
	int plen = pattern.length();
	StringBuilder pbuf = new StringBuilder(plen);
	char last = 0;
	int lastStart = 0;
	char cc = 0;
	for (int i = 0; i < plen;) {
	char c = pattern.charAt(i);
	if (cc == 0 && // top level
	c == '\\' && i + 1 < plen && pattern.charAt(i + 1) == '\\') {
	i += 2; last = 0;
	continue;
	}
	if (c == '[' && last != '\\') {
	if (cc == 0) {
	if (lastStart < i)
	normalizeSlice(pattern, lastStart, i, pbuf);
	lastStart = i;
	}
	cc++;
	} else if (c == ']' && last != '\\') {
	cc--;
	if (cc == 0) {
	normalizeClazz(pattern, lastStart, i + 1, pbuf);
	lastStart = i + 1;
	}
	}
	last = c;
	i++;
	}
	assert (cc == 0);
	if (lastStart < plen)
	normalizeSlice(pattern, lastStart, plen, pbuf);
	return pbuf.toString();
	}

	private static void normalizeSlice(String src, int off, int limit,
	StringBuilder dst)
	{
	int len = src.length();
	int off0 = off;
	while (off < limit && ASCII.isAscii(src.charAt(off))) {
	off++;
	}
	if (off == limit) {
	dst.append(src, off0, limit);
	return;
	}
	off--;
	if (off < off0)
	off = off0;
	else
	dst.append(src, off0, off);
	while (off < limit) {
	int ch0 = src.codePointAt(off);
	if (".$\|()[]{}^?*+\\".indexOf(ch0) != -1) {
	dst.append((char)ch0);
	off++;
	continue;
	}
	int j = off + Character.charCount(ch0);
	int ch1;
	while (j < limit) {
	ch1 = src.codePointAt(j);
	if (Grapheme.isBoundary(ch0, ch1))
	break;
	ch0 = ch1;
	j += Character.charCount(ch1);
	}
	String seq = src.substring(off, j);
	String nfd = Normalizer.normalize(seq, Normalizer.Form.NFD);
	off = j;
	if (nfd.length() > 1) {
	ch0 = nfd.codePointAt(0);
	ch1 = nfd.codePointAt(Character.charCount(ch0));
	if (Character.getType(ch1) == Character.NON_SPACING_MARK) {
	Set<String> altns = new LinkedHashSet<>();
	altns.add(seq);
	produceEquivalentAlternation(nfd, altns);
	dst.append("(?:");
	altns.forEach( s -> dst.append(s).append('\|'));
	dst.delete(dst.length() - 1, dst.length());
	dst.append(")");
	continue;
	}
	}
	String nfc = Normalizer.normalize(seq, Normalizer.Form.NFC);
	if (!seq.equals(nfc) && !nfd.equals(nfc))
	dst.append("(?:" + seq + "\|" + nfd + "\|" + nfc + ")");
	else if (!seq.equals(nfd))
	dst.append("(?:" + seq + "\|" + nfd + ")");
	else
	dst.append(seq);
	}
	}

	private static void normalizeClazz(String src, int off, int limit,
	StringBuilder dst)
	{
	dst.append(Normalizer.normalize(src.substring(off, limit), Form.NFC));
	}

	/**
	* Given a specific sequence composed of a regular character and
	* combining marks that follow it, produce the alternation that will
	* match all canonical equivalences of that sequence.
	*/
	private static void produceEquivalentAlternation(String src,
	Set<String> dst)
	{
	int len = countChars(src, 0, 1);
	if (src.length() == len) {
	dst.add(src); // source has one character.
	return;
	}
	String base = src.substring(0,len);
	String combiningMarks = src.substring(len);
	String[] perms = producePermutations(combiningMarks);
	// Add combined permutations
	for(int x = 0; x < perms.length; x++) {
	String next = base + perms[x];
	dst.add(next);
	next = composeOneStep(next);
	if (next != null) {
	produceEquivalentAlternation(next, dst);
	}
	}
	}

	/**
	* Returns an array of strings that have all the possible
	* permutations of the characters in the input string.
	* This is used to get a list of all possible orderings
	* of a set of combining marks. Note that some of the permutations
	* are invalid because of combining class collisions, and these
	* possibilities must be removed because they are not canonically
	* equivalent.
	*/
	private static String[] producePermutations(String input) {
	if (input.length() == countChars(input, 0, 1))
	return new String[] {input};

	if (input.length() == countChars(input, 0, 2)) {
	int c0 = Character.codePointAt(input, 0);
	int c1 = Character.codePointAt(input, Character.charCount(c0));
	if (getClass(c1) == getClass(c0)) {
	return new String[] {input};
	}
	String[] result = new String[2];
	result[0] = input;
	StringBuilder sb = new StringBuilder(2);
	sb.appendCodePoint(c1);
	sb.appendCodePoint(c0);
	result[1] = sb.toString();
	return result;
	}

	int length = 1;
	int nCodePoints = countCodePoints(input);
	for(int x=1; x<nCodePoints; x++)
	length = length * (x+1);

	String[] temp = new String[length];

	int combClass[] = new int[nCodePoints];
	for(int x=0, i=0; x<nCodePoints; x++) {
	int c = Character.codePointAt(input, i);
	combClass[x] = getClass(c);
	i += Character.charCount(c);
	}

	// For each char, take it out and add the permutations
	// of the remaining chars
	int index = 0;
	int len;
	// offset maintains the index in code units.
	loop: for(int x=0, offset=0; x<nCodePoints; x++, offset+=len) {
	len = countChars(input, offset, 1);
	for(int y=x-1; y>=0; y--) {
	if (combClass[y] == combClass[x]) {
	continue loop;
	}
	}
	StringBuilder sb = new StringBuilder(input);
	String otherChars = sb.delete(offset, offset+len).toString();
	String[] subResult = producePermutations(otherChars);

	String prefix = input.substring(offset, offset+len);
	for (String sre : subResult)
	temp[index++] = prefix + sre;
	}
	String[] result = new String[index];
	System.arraycopy(temp, 0, result, 0, index);
	return result;
	}

	private static int getClass(int c) {
	return sun.text.Normalizer.getCombiningClass(c);
	}

	/**
	* Attempts to compose input by combining the first character
	* with the first combining mark following it. Returns a String
	* that is the composition of the leading character with its first
	* combining mark followed by the remaining combining marks. Returns
	* null if the first two characters cannot be further composed.
	*/
	private static String composeOneStep(String input) {
	int len = countChars(input, 0, 2);
	String firstTwoCharacters = input.substring(0, len);
	String result = Normalizer.normalize(firstTwoCharacters, Normalizer.Form.NFC);
	if (result.equals(firstTwoCharacters))
	return null;
	else {
	String remainder = input.substring(len);
	return result + remainder;
	}
	}

	/**
	* Preprocess any \Q...\E sequences in `temp', meta-quoting them.
	* See the description of `quotemeta' in perlfunc(1).
	*/
	private void RemoveQEQuoting() {
	final int pLen = patternLength;
	int i = 0;
	while (i < pLen-1) {
	if (temp[i] != '\\')
	i += 1;
	else if (temp[i + 1] != 'Q')
	i += 2;
	else
	break;
	}
	if (i >= pLen - 1) // No \Q sequence found
	return;
	int j = i;
	i += 2;
	int[] newtemp = new int[j + 3*(pLen-i) + 2];
	System.arraycopy(temp, 0, newtemp, 0, j);

	boolean inQuote = true;
	boolean beginQuote = true;
	while (i < pLen) {
	int c = temp[i++];
	if (!ASCII.isAscii(c) \|\| ASCII.isAlpha(c)) {
	newtemp[j++] = c;
	} else if (ASCII.isDigit(c)) {
	if (beginQuote) {
	/*
	* A unicode escape \[0xu] could be before this quote,
	* and we don't want this numeric char to processed as
	* part of the escape.
	*/
	newtemp[j++] = '\\';
	newtemp[j++] = 'x';
	newtemp[j++] = '3';
	}
	newtemp[j++] = c;
	} else if (c != '\\') {
	if (inQuote) newtemp[j++] = '\\';
	newtemp[j++] = c;
	} else if (inQuote) {
	if (temp[i] == 'E') {
	i++;
	inQuote = false;
	} else {
	newtemp[j++] = '\\';
	newtemp[j++] = '\\';
	}
	} else {
	if (temp[i] == 'Q') {
	i++;
	inQuote = true;
	beginQuote = true;
	continue;
	} else {
	newtemp[j++] = c;
	if (i != pLen)
	newtemp[j++] = temp[i++];
	}
	}

	beginQuote = false;
	}

	patternLength = j;
	temp = Arrays.copyOf(newtemp, j + 2); // double zero termination
	}

	/**
	* Copies regular expression to an int array and invokes the parsing
	* of the expression which will create the object tree.
	*/
	private void compile() {
	// Handle canonical equivalences
	if (has(CANON_EQ) && !has(LITERAL)) {
	normalizedPattern = normalize(pattern);
	} else {
	normalizedPattern = pattern;
	}
	patternLength = normalizedPattern.length();

	// Copy pattern to int array for convenience
	// Use double zero to terminate pattern
	temp = new int[patternLength + 2];

	hasSupplementary = false;
	int c, count = 0;
	// Convert all chars into code points
	for (int x = 0; x < patternLength; x += Character.charCount(c)) {
	c = normalizedPattern.codePointAt(x);
	if (isSupplementary(c)) {
	hasSupplementary = true;
	}
	temp[count++] = c;
	}

	patternLength = count; // patternLength now in code points

	if (! has(LITERAL))
	RemoveQEQuoting();

	// Allocate all temporary objects here.
	buffer = new int[32];
	groupNodes = new GroupHead[10];
	namedGroups = null;
	topClosureNodes = new ArrayList<>(10);

	if (has(LITERAL)) {
	// Literal pattern handling
	matchRoot = newSlice(temp, patternLength, hasSupplementary);
	matchRoot.next = lastAccept;
	} else {
	// Start recursive descent parsing
	matchRoot = expr(lastAccept);
	// Check extra pattern characters
	if (patternLength != cursor) {
	if (peek() == ')') {
	throw error("Unmatched closing ')'");
	} else {
	throw error("Unexpected internal error");
	}
	}
	}

	// Peephole optimization
	if (matchRoot instanceof Slice) {
	root = BnM.optimize(matchRoot);
	if (root == matchRoot) {
	root = hasSupplementary ? new StartS(matchRoot) : new Start(matchRoot);
	}
	} else if (matchRoot instanceof Begin \|\| matchRoot instanceof First) {
	root = matchRoot;
	} else {
	root = hasSupplementary ? new StartS(matchRoot) : new Start(matchRoot);
	}

	// Optimize the greedy Loop to prevent exponential backtracking, IF there
	// is no group ref in this pattern. With a non-negative localTCNCount value,
	// the greedy type Loop, Curly will skip the backtracking for any starting
	// position "i" that failed in the past.
	if (!hasGroupRef) {
	for (Node node : topClosureNodes) {
	if (node instanceof Loop) {
	// non-deterministic-greedy-group
	((Loop)node).posIndex = localTCNCount++;
	}
	}
	}

	// Release temporary storage
	temp = null;
	buffer = null;
	groupNodes = null;
	patternLength = 0;
	compiled = true;
	topClosureNodes = null;
	}

	Map<String, Integer> namedGroups() {
	Map<String, Integer> groups = namedGroups;
	if (groups == null) {
	namedGroups = groups = new HashMap<>(2);
	}
	return groups;
	}

	/**
	* Used to accumulate information about a subtree of the object graph
	* so that optimizations can be applied to the subtree.
	*/
	static final class TreeInfo {
	int minLength;
	int maxLength;
	boolean maxValid;
	boolean deterministic;

	TreeInfo() {
	reset();
	}
	void reset() {
	minLength = 0;
	maxLength = 0;
	maxValid = true;
	deterministic = true;
	}
	}

	/*
	* The following private methods are mainly used to improve the
	* readability of the code. In order to let the Java compiler easily
	* inline them, we should not put many assertions or error checks in them.
	*/

	/**
	* Indicates whether a particular flag is set or not.
	*/
	private boolean has(int f) {
	return (flags0 & f) != 0;
	}

	/**
	* Match next character, signal error if failed.
	*/
	private void accept(int ch, String s) {
	int testChar = temp[cursor++];
	if (has(COMMENTS))
	testChar = parsePastWhitespace(testChar);
	if (ch != testChar) {
	throw error(s);
	}
	}

	/**
	* Mark the end of pattern with a specific character.
	*/
	private void mark(int c) {
	temp[patternLength] = c;
	}

	/**
	* Peek the next character, and do not advance the cursor.
	*/
	private int peek() {
	int ch = temp[cursor];
	if (has(COMMENTS))
	ch = peekPastWhitespace(ch);
	return ch;
	}

	/**
	* Read the next character, and advance the cursor by one.
	*/
	private int read() {
	int ch = temp[cursor++];
	if (has(COMMENTS))
	ch = parsePastWhitespace(ch);
	return ch;
	}

	/**
	* Read the next character, and advance the cursor by one,
	* ignoring the COMMENTS setting
	*/
	private int readEscaped() {
	int ch = temp[cursor++];
	return ch;
	}

	/**
	* Advance the cursor by one, and peek the next character.
	*/
	private int next() {
	int ch = temp[++cursor];
	if (has(COMMENTS))
	ch = peekPastWhitespace(ch);
	return ch;
	}

	/**
	* Advance the cursor by one, and peek the next character,
	* ignoring the COMMENTS setting
	*/
	private int nextEscaped() {
	int ch = temp[++cursor];
	return ch;
	}

	/**
	* If in xmode peek past whitespace and comments.
	*/
	private int peekPastWhitespace(int ch) {
	while (ASCII.isSpace(ch) \|\| ch == '#') {
	while (ASCII.isSpace(ch))
	ch = temp[++cursor];
	if (ch == '#') {
	ch = peekPastLine();
	}
	}
	return ch;
	}

	/**
	* If in xmode parse past whitespace and comments.
	*/
	private int parsePastWhitespace(int ch) {
	while (ASCII.isSpace(ch) \|\| ch == '#') {
	while (ASCII.isSpace(ch))
	ch = temp[cursor++];
	if (ch == '#')
	ch = parsePastLine();
	}
	return ch;
	}

	/**
	* xmode parse past comment to end of line.
	*/
	private int parsePastLine() {
	int ch = temp[cursor++];
	while (ch != 0 && !isLineSeparator(ch))
	ch = temp[cursor++];
	return ch;
	}

	/**
	* xmode peek past comment to end of line.
	*/
	private int peekPastLine() {
	int ch = temp[++cursor];
	while (ch != 0 && !isLineSeparator(ch))
	ch = temp[++cursor];
	return ch;
	}

	/**
	* Determines if character is a line separator in the current mode
	*/
	private boolean isLineSeparator(int ch) {
	if (has(UNIX_LINES)) {
	return ch == '\n';
	} else {
	return (ch == '\n' \|\|
	ch == '\r' \|\|
	(ch\|1) == '\u2029' \|\|
	ch == '\u0085');
	}
	}

	/**
	* Read the character after the next one, and advance the cursor by two.
	*/
	private int skip() {
	int i = cursor;
	int ch = temp[i+1];
	cursor = i + 2;
	return ch;
	}

	/**
	* Unread one next character, and retreat cursor by one.
	*/
	private void unread() {
	cursor--;
	}

	/**
	* Internal method used for handling all syntax errors. The pattern is
	* displayed with a pointer to aid in locating the syntax error.
	*/
	private PatternSyntaxException error(String s) {
	return new PatternSyntaxException(s, normalizedPattern, cursor - 1);
	}

	/**
	* Determines if there is any supplementary character or unpaired
	* surrogate in the specified range.
	*/
	private boolean findSupplementary(int start, int end) {
	for (int i = start; i < end; i++) {
	if (isSupplementary(temp[i]))
	return true;
	}
	return false;
	}

	/**
	* Determines if the specified code point is a supplementary
	* character or unpaired surrogate.
	*/
	private static final boolean isSupplementary(int ch) {
	return ch >= Character.MIN_SUPPLEMENTARY_CODE_POINT \|\|
	Character.isSurrogate((char)ch);
	}

	/**
	* The following methods handle the main parsing. They are sorted
	* according to their precedence order, the lowest one first.
	*/

	/**
	* The expression is parsed with branch nodes added for alternations.
	* This may be called recursively to parse sub expressions that may
	* contain alternations.
	*/
	private Node expr(Node end) {
	Node prev = null;
	Node firstTail = null;
	Branch branch = null;
	Node branchConn = null;

	for (;;) {
	Node node = sequence(end);
	Node nodeTail = root; //double return
	if (prev == null) {
	prev = node;
	firstTail = nodeTail;
	} else {
	// Branch
	if (branchConn == null) {
	branchConn = new BranchConn();
	branchConn.next = end;
	}
	if (node == end) {
	// if the node returned from sequence() is "end"
	// we have an empty expr, set a null atom into
	// the branch to indicate to go "next" directly.
	node = null;
	} else {
	// the "tail.next" of each atom goes to branchConn
	nodeTail.next = branchConn;
	}
	if (prev == branch) {
	branch.add(node);
	} else {
	if (prev == end) {
	prev = null;
	} else {
	// replace the "end" with "branchConn" at its tail.next
	// when put the "prev" into the branch as the first atom.
	firstTail.next = branchConn;
	}
	prev = branch = new Branch(prev, node, branchConn);
	}
	}
	if (peek() != '\|') {
	return prev;
	}
	next();
	}
	}

	@SuppressWarnings("fallthrough")
	/**
	* Parsing of sequences between alternations.
	*/
	private Node sequence(Node end) {
	Node head = null;
	Node tail = null;
	Node node = null;
	LOOP:
	for (;;) {
	int ch = peek();
	switch (ch) {
	case '(':
	// Because group handles its own closure,
	// we need to treat it differently
	node = group0();
	// Check for comment or flag group
	if (node == null)
	continue;
	if (head == null)
	head = node;
	else
	tail.next = node;
	// Double return: Tail was returned in root
	tail = root;
	continue;
	case '[':
	if (has(CANON_EQ) && !has(LITERAL))
	node = new NFCCharProperty(clazz(true));
	else
	node = newCharProperty(clazz(true));
	break;
	case '\\':
	ch = nextEscaped();
	if (ch == 'p' \|\| ch == 'P') {
	boolean oneLetter = true;
	boolean comp = (ch == 'P');
	ch = next(); // Consume { if present
	if (ch != '{') {
	unread();
	} else {
	oneLetter = false;
	}
	// node = newCharProperty(family(oneLetter, comp));
	if (has(CANON_EQ) && !has(LITERAL))
	node = new NFCCharProperty(family(oneLetter, comp));
	else
	node = newCharProperty(family(oneLetter, comp));
	} else {
	unread();
	node = atom();
	}
	break;
	case '^':
	next();
	if (has(MULTILINE)) {
	if (has(UNIX_LINES))
	node = new UnixCaret();
	else
	node = new Caret();
	} else {
	node = new Begin();
	}
	break;
	case '$':
	next();
	if (has(UNIX_LINES))
	node = new UnixDollar(has(MULTILINE));
	else
	node = new Dollar(has(MULTILINE));
	break;
	case '.':
	next();
	if (has(DOTALL)) {
	node = new CharProperty(ALL());
	} else {
	if (has(UNIX_LINES)) {
	node = new CharProperty(UNIXDOT());
	} else {
	node = new CharProperty(DOT());
	}
	}
	break;
	case '\|':
	case ')':
	break LOOP;
	case ']': // Now interpreting dangling ] and } as literals
	case '}':
	node = atom();
	break;
	case '?':
	case '*':
	case '+':
	next();
	throw error("Dangling meta character '" + ((char)ch) + "'");
	case 0:
	if (cursor >= patternLength) {
	break LOOP;
	}
	// Fall through
	default:
	node = atom();
	break;
	}

	node = closure(node);
	/* save the top dot-greedy nodes (.*, .+) as well
	if (node instanceof GreedyCharProperty &&
	((GreedyCharProperty)node).cp instanceof Dot) {
	topClosureNodes.add(node);
	}
	*/
	if (head == null) {
	head = tail = node;
	} else {
	tail.next = node;
	tail = node;
	}
	}
	if (head == null) {
	return end;
	}
	tail.next = end;
	root = tail; //double return
	return head;
	}

	@SuppressWarnings("fallthrough")
	/**
	* Parse and add a new Single or Slice.
	*/
	private Node atom() {
	int first = 0;
	int prev = -1;
	boolean hasSupplementary = false;
	int ch = peek();
	for (;;) {
	switch (ch) {
	case '*':
	case '+':
	case '?':
	case '{':
	if (first > 1) {
	cursor = prev; // Unwind one character
	first--;
	}
	break;
	case '$':
	case '.':
	case '^':
	case '(':
	case '[':
	case '\|':
	case ')':
	break;
	case '\\':
	ch = nextEscaped();
	if (ch == 'p' \|\| ch == 'P') { // Property
	if (first > 0) { // Slice is waiting; handle it first
	unread();
	break;
	} else { // No slice; just return the family node
	boolean comp = (ch == 'P');
	boolean oneLetter = true;
	ch = next(); // Consume { if present
	if (ch != '{')
	unread();
	else
	oneLetter = false;
	if (has(CANON_EQ) && !has(LITERAL))
	return new NFCCharProperty(family(oneLetter, comp));
	else
	return newCharProperty(family(oneLetter, comp));
	}
	}
	unread();
	prev = cursor;
	ch = escape(false, first == 0, false);
	if (ch >= 0) {
	append(ch, first);
	first++;
	if (isSupplementary(ch)) {
	hasSupplementary = true;
	}
	ch = peek();
	continue;
	} else if (first == 0) {
	return root;
	}
	// Unwind meta escape sequence
	cursor = prev;
	break;
	case 0:
	if (cursor >= patternLength) {
	break;
	}
	// Fall through
	default:
	prev = cursor;
	append(ch, first);
	first++;
	if (isSupplementary(ch)) {
	hasSupplementary = true;
	}
	ch = next();
	continue;
	}
	break;
	}
	if (first == 1) {
	return newCharProperty(single(buffer[0]));
	} else {
	return newSlice(buffer, first, hasSupplementary);
	}
	}

	private void append(int ch, int len) {
	if (len >= buffer.length) {
	int[] tmp = new int[len+len];
	System.arraycopy(buffer, 0, tmp, 0, len);
	buffer = tmp;
	}
	buffer[len] = ch;
	}

	/**
	* Parses a backref greedily, taking as many numbers as it
	* can. The first digit is always treated as a backref, but
	* multi digit numbers are only treated as a backref if at
	* least that many backrefs exist at this point in the regex.
	*/
	private Node ref(int refNum) {
	boolean done = false;
	while(!done) {
	int ch = peek();
	switch(ch) {
	case '0':
	case '1':
	case '2':
	case '3':
	case '4':
	case '5':
	case '6':
	case '7':
	case '8':
	case '9':
	int newRefNum = (refNum * 10) + (ch - '0');
	// Add another number if it doesn't make a group
	// that doesn't exist
	if (capturingGroupCount - 1 < newRefNum) {
	done = true;
	break;
	}
	refNum = newRefNum;
	read();
	break;
	default:
	done = true;
	break;
	}
	}
	hasGroupRef = true;
	if (has(CASE_INSENSITIVE))
	return new CIBackRef(refNum, has(UNICODE_CASE));
	else
	return new BackRef(refNum);
	}

	/**
	* Parses an escape sequence to determine the actual value that needs
	* to be matched.
	* If -1 is returned and create was true a new object was added to the tree
	* to handle the escape sequence.
	* If the returned value is greater than zero, it is the value that
	* matches the escape sequence.
	*/
	private int escape(boolean inclass, boolean create, boolean isrange) {
	int ch = skip();
	switch (ch) {
	case '0':
	return o();
	case '1':
	case '2':
	case '3':
	case '4':
	case '5':
	case '6':
	case '7':
	case '8':
	case '9':
	if (inclass) break;
	if (create) {
	root = ref((ch - '0'));
	}
	return -1;
	case 'A':
	if (inclass) break;
	if (create) root = new Begin();
	return -1;
	case 'B':
	if (inclass) break;
	if (create) root = new Bound(Bound.NONE, has(UNICODE_CHARACTER_CLASS));
	return -1;
	case 'C':
	break;
	case 'D':
	if (create) {
	predicate = has(UNICODE_CHARACTER_CLASS) ?
	CharPredicates.DIGIT() : CharPredicates.ASCII_DIGIT();
	predicate = predicate.negate();
	if (!inclass)
	root = newCharProperty(predicate);
	}
	return -1;
	case 'E':
	case 'F':
	break;
	case 'G':
	if (inclass) break;
	if (create) root = new LastMatch();
	return -1;
	case 'H':
	if (create) {
	predicate = HorizWS().negate();
	if (!inclass)
	root = newCharProperty(predicate);
	}
	return -1;
	case 'I':
	case 'J':
	case 'K':
	case 'L':
	case 'M':
	break;
	case 'N':
	return N();
	case 'O':
	case 'P':
	case 'Q':
	break;
	case 'R':
	if (inclass) break;
	if (create) root = new LineEnding();
	return -1;
	case 'S':
	if (create) {
	predicate = has(UNICODE_CHARACTER_CLASS) ?
	CharPredicates.WHITE_SPACE() : CharPredicates.ASCII_SPACE();
	predicate = predicate.negate();
	if (!inclass)
	root = newCharProperty(predicate);
	}
	return -1;
	case 'T':
	case 'U':
	break;
	case 'V':
	if (create) {
	predicate = VertWS().negate();
	if (!inclass)
	root = newCharProperty(predicate);
	}
	return -1;
	case 'W':
	if (create) {
	predicate = has(UNICODE_CHARACTER_CLASS) ?
	CharPredicates.WORD() : CharPredicates.ASCII_WORD();
	predicate = predicate.negate();
	if (!inclass)
	root = newCharProperty(predicate);
	}
	return -1;
	case 'X':
	if (inclass) break;
	if (create) {
	root = new XGrapheme();
	}
	return -1;
	case 'Y':
	break;
	case 'Z':
	if (inclass) break;
	if (create) {
	if (has(UNIX_LINES))
	root = new UnixDollar(false);
	else
	root = new Dollar(false);
	}
	return -1;
	case 'a':
	return '\007';
	case 'b':
	if (inclass) break;
	if (create) {
	if (peek() == '{') {
	if (skip() == 'g') {
	if (read() == '}') {
	root = new GraphemeBound();
	return -1;
	}
	break; // error missing trailing }
	}
	unread(); unread();
	}
	root = new Bound(Bound.BOTH, has(UNICODE_CHARACTER_CLASS));
	}
	return -1;
	case 'c':
	return c();
	case 'd':
	if (create) {
	predicate = has(UNICODE_CHARACTER_CLASS) ?
	CharPredicates.DIGIT() : CharPredicates.ASCII_DIGIT();
	if (!inclass)
	root = newCharProperty(predicate);
	}
	return -1;
	case 'e':
	return '\033';
	case 'f':
	return '\f';
	case 'g':
	break;
	case 'h':
	if (create) {
	predicate = HorizWS();
	if (!inclass)
	root = newCharProperty(predicate);
	}
	return -1;
	case 'i':
	case 'j':
	break;
	case 'k':
	if (inclass)
	break;
	if (read() != '<')
	throw error("\\k is not followed by '<' for named capturing group");
	String name = groupname(read());
	if (!namedGroups().containsKey(name))
	throw error("named capturing group <" + name + "> does not exist");
	if (create) {
	hasGroupRef = true;
	if (has(CASE_INSENSITIVE))
	root = new CIBackRef(namedGroups().get(name), has(UNICODE_CASE));
	else
	root = new BackRef(namedGroups().get(name));
	}
	return -1;
	case 'l':
	case 'm':
	break;
	case 'n':
	return '\n';
	case 'o':
	case 'p':
	case 'q':
	break;
	case 'r':
	return '\r';
	case 's':
	if (create) {
	predicate = has(UNICODE_CHARACTER_CLASS) ?
	CharPredicates.WHITE_SPACE() : CharPredicates.ASCII_SPACE();
	if (!inclass)
	root = newCharProperty(predicate);
	}
	return -1;
	case 't':
	return '\t';
	case 'u':
	return u();
	case 'v':
	// '\v' was implemented as VT/0x0B in releases < 1.8 (though
	// undocumented). In JDK8 '\v' is specified as a predefined
	// character class for all vertical whitespace characters.
	// So [-1, root=VertWS node] pair is returned (instead of a
	// single 0x0B). This breaks the range if '\v' is used as
	// the start or end value, such as [\v-...] or [...-\v], in
	// which a single definite value (0x0B) is expected. For
	// compatibility concern '\013'/0x0B is returned if isrange.
	if (isrange)
	return '\013';
	if (create) {
	predicate = VertWS();
	if (!inclass)
	root = newCharProperty(predicate);
	}
	return -1;
	case 'w':
	if (create) {
	predicate = has(UNICODE_CHARACTER_CLASS) ?
	CharPredicates.WORD() : CharPredicates.ASCII_WORD();
	if (!inclass)
	root = newCharProperty(predicate);
	}
	return -1;
	case 'x':
	return x();
	case 'y':
	break;
	case 'z':
	if (inclass) break;
	if (create) root = new End();
	return -1;
	default:
	return ch;
	}
	throw error("Illegal/unsupported escape sequence");
	}

	/**
	* Parse a character class, and return the node that matches it.
	*
	* Consumes a ] on the way out if consume is true. Usually consume
	* is true except for the case of [abc&&def] where def is a separate
	* right hand node with "understood" brackets.
	*/
	private CharPredicate clazz(boolean consume) {
	CharPredicate prev = null;
	CharPredicate curr = null;
	BitClass bits = new BitClass();
	BmpCharPredicate bitsP = ch -> ch < 256 && bits.bits[ch];

	boolean isNeg = false;
	boolean hasBits = false;
	int ch = next();

	// Negates if first char in a class, otherwise literal
	if (ch == '^' && temp[cursor-1] == '[') {
	ch = next();
	isNeg = true;
	}
	for (;;) {
	switch (ch) {
	case '[':
	curr = clazz(true);
	if (prev == null)
	prev = curr;
	else
	prev = prev.union(curr);
	ch = peek();
	continue;
	case '&':
	ch = next();
	if (ch == '&') {
	ch = next();
	CharPredicate right = null;
	while (ch != ']' && ch != '&') {
	if (ch == '[') {
	if (right == null)
	right = clazz(true);
	else
	right = right.union(clazz(true));
	} else { // abc&&def
	unread();
	right = clazz(false);
	}
	ch = peek();
	}
	if (hasBits) {
	// bits used, union has high precedence
	if (prev == null) {
	prev = curr = bitsP;
	} else {
	prev = prev.union(bitsP);
	}
	hasBits = false;
	}
	if (right != null)
	curr = right;
	if (prev == null) {
	if (right == null)
	throw error("Bad class syntax");
	else
	prev = right;
	} else {
	prev = prev.and(curr);
	}
	} else {
	// treat as a literal &
	unread();
	break;
	}
	continue;
	case 0:
	if (cursor >= patternLength)
	throw error("Unclosed character class");
	break;
	case ']':
	if (prev != null \|\| hasBits) {
	if (consume)
	next();
	if (prev == null)
	prev = bitsP;
	else if (hasBits)
	prev = prev.union(bitsP);
	if (isNeg)
	return prev.negate();
	return prev;
	}
	break;
	default:
	break;
	}
	curr = range(bits);
	if (curr == null) { // the bits used
	hasBits = true;
	} else {
	if (prev == null)
	prev = curr;
	else if (prev != curr)
	prev = prev.union(curr);
	}
	ch = peek();
	}
	}

	private CharPredicate bitsOrSingle(BitClass bits, int ch) {
	/* Bits can only handle codepoints in [u+0000-u+00ff] range.
	Use "single" node instead of bits when dealing with unicode
	case folding for codepoints listed below.
	(1)Uppercase out of range: u+00ff, u+00b5
	toUpperCase(u+00ff) -> u+0178
	toUpperCase(u+00b5) -> u+039c
	(2)LatinSmallLetterLongS u+17f
	toUpperCase(u+017f) -> u+0053
	(3)LatinSmallLetterDotlessI u+131
	toUpperCase(u+0131) -> u+0049
	(4)LatinCapitalLetterIWithDotAbove u+0130
	toLowerCase(u+0130) -> u+0069
	(5)KelvinSign u+212a
	toLowerCase(u+212a) ==> u+006B
	(6)AngstromSign u+212b
	toLowerCase(u+212b) ==> u+00e5
	*/
	if (ch < 256 &&
	!(has(CASE_INSENSITIVE) && has(UNICODE_CASE) &&
	(ch == 0xff \|\| ch == 0xb5 \|\|
	ch == 0x49 \|\| ch == 0x69 \|\| //I and i
	ch == 0x53 \|\| ch == 0x73 \|\| //S and s
	ch == 0x4b \|\| ch == 0x6b \|\| //K and k
	ch == 0xc5 \|\| ch == 0xe5))) { //A+ring
	bits.add(ch, flags0);
	return null;
	}
	return single(ch);
	}

	/**
	* Returns a suitably optimized, single character predicate
	*/
	private CharPredicate single(final int ch) {
	if (has(CASE_INSENSITIVE)) {
	int lower, upper;
	if (has(UNICODE_CASE)) {
	upper = Character.toUpperCase(ch);
	lower = Character.toLowerCase(upper);
	// Unicode case insensitive matches
	if (upper != lower)
	return SingleU(lower);
	} else if (ASCII.isAscii(ch)) {
	lower = ASCII.toLower(ch);
	upper = ASCII.toUpper(ch);
	// Case insensitive matches a given BMP character
	if (lower != upper)
	return SingleI(lower, upper);
	}
	}
	if (isSupplementary(ch))
	return SingleS(ch);
	return Single(ch); // Match a given BMP character
	}

	/**
	* Parse a single character or a character range in a character class
	* and return its representative node.
	*/
	private CharPredicate range(BitClass bits) {
	int ch = peek();
	if (ch == '\\') {
	ch = nextEscaped();
	if (ch == 'p' \|\| ch == 'P') { // A property
	boolean comp = (ch == 'P');
	boolean oneLetter = true;
	// Consume { if present
	ch = next();
	if (ch != '{')
	unread();
	else
	oneLetter = false;
	return family(oneLetter, comp);
	} else { // ordinary escape
	boolean isrange = temp[cursor+1] == '-';
	unread();
	ch = escape(true, true, isrange);
	if (ch == -1)
	return predicate;
	}
	} else {
	next();
	}
	if (ch >= 0) {
	if (peek() == '-') {
	int endRange = temp[cursor+1];
	if (endRange == '[') {
	return bitsOrSingle(bits, ch);
	}
	if (endRange != ']') {
	next();
	int m = peek();
	if (m == '\\') {
	m = escape(true, false, true);
	} else {
	next();
	}
	if (m < ch) {
	throw error("Illegal character range");
	}
	if (has(CASE_INSENSITIVE)) {
	if (has(UNICODE_CASE))
	return CIRangeU(ch, m);
	return CIRange(ch, m);
	} else {
	return Range(ch, m);
	}
	}
	}
	return bitsOrSingle(bits, ch);
	}
	throw error("Unexpected character '"+((char)ch)+"'");
	}

	/**
	* Parses a Unicode character family and returns its representative node.
	*/
	private CharPredicate family(boolean singleLetter, boolean isComplement) {
	next();
	String name;
	CharPredicate p = null;

	if (singleLetter) {
	int c = temp[cursor];
	if (!Character.isSupplementaryCodePoint(c)) {
	name = String.valueOf((char)c);
	} else {
	name = new String(temp, cursor, 1);
	}
	read();
	} else {
	int i = cursor;
	mark('}');
	while(read() != '}') {
	}
	mark('\000');
	int j = cursor;
	if (j > patternLength)
	throw error("Unclosed character family");
	if (i + 1 >= j)
	throw error("Empty character family");
	name = new String(temp, i, j-i-1);
	}

	int i = name.indexOf('=');
	if (i != -1) {
	// property construct \p{name=value}
	String value = name.substring(i + 1);
	name = name.substring(0, i).toLowerCase(Locale.ENGLISH);
	switch (name) {
	case "sc":
	case "script":
	p = CharPredicates.forUnicodeScript(value);
	break;
	case "blk":
	case "block":
	p = CharPredicates.forUnicodeBlock(value);
	break;
	case "gc":
	case "general_category":
	p = CharPredicates.forProperty(value);
	break;
	default:
	break;
	}
	if (p == null)
	throw error("Unknown Unicode property {name=<" + name + ">, "
	+ "value=<" + value + ">}");

	} else {
	if (name.startsWith("In")) {
	// \p{InBlockName}
	p = CharPredicates.forUnicodeBlock(name.substring(2));
	} else if (name.startsWith("Is")) {
	// \p{IsGeneralCategory} and \p{IsScriptName}
	name = name.substring(2);
	p = CharPredicates.forUnicodeProperty(name);
	if (p == null)
	p = CharPredicates.forProperty(name);
	if (p == null)
	p = CharPredicates.forUnicodeScript(name);
	} else {
	if (has(UNICODE_CHARACTER_CLASS)) {
	p = CharPredicates.forPOSIXName(name);
	}
	if (p == null)
	p = CharPredicates.forProperty(name);
	}
	if (p == null)
	throw error("Unknown character property name {In/Is" + name + "}");
	}
	if (isComplement) {
	// it might be too expensive to detect if a complement of
	// CharProperty can match "certain" supplementary. So just
	// go with StartS.
	hasSupplementary = true;
	p = p.negate();
	}
	return p;
	}

	private CharProperty newCharProperty(CharPredicate p) {
	if (p == null)
	return null;
	if (p instanceof BmpCharPredicate)
	return new BmpCharProperty((BmpCharPredicate)p);
	else
	return new CharProperty(p);
	}

	/**
	* Parses and returns the name of a "named capturing group", the trailing
	* ">" is consumed after parsing.
	*/
	private String groupname(int ch) {
	StringBuilder sb = new StringBuilder();
	if (!ASCII.isAlpha(ch))
	throw error("capturing group name does not start with a Latin letter");
	do {
	sb.append((char) ch);
	} while (ASCII.isAlnum(ch=read()));
	if (ch != '>')
	throw error("named capturing group is missing trailing '>'");
	return sb.toString();
	}

	/**
	* Parses a group and returns the head node of a set of nodes that process
	* the group. Sometimes a double return system is used where the tail is
	* returned in root.
	*/
	private Node group0() {
	boolean capturingGroup = false;
	Node head = null;
	Node tail = null;
	int save = flags0;
	int saveTCNCount = topClosureNodes.size();
	root = null;
	int ch = next();
	if (ch == '?') {
	ch = skip();
	switch (ch) {
	case ':': // (?:xxx) pure group
	head = createGroup(true);
	tail = root;
	head.next = expr(tail);
	break;
	case '=': // (?=xxx) and (?!xxx) lookahead
	case '!':
	head = createGroup(true);
	tail = root;
	head.next = expr(tail);
	if (ch == '=') {
	head = tail = new Pos(head);
	} else {
	head = tail = new Neg(head);
	}
	break;
	case '>': // (?>xxx) independent group
	head = createGroup(true);
	tail = root;
	head.next = expr(tail);
	head = tail = new Ques(head, Qtype.INDEPENDENT);
	break;
	case '<': // (?<xxx) look behind
	ch = read();
	if (ch != '=' && ch != '!') {
	// named captured group
	String name = groupname(ch);
	if (namedGroups().containsKey(name))
	throw error("Named capturing group <" + name
	+ "> is already defined");
	capturingGroup = true;
	head = createGroup(false);
	tail = root;
	namedGroups().put(name, capturingGroupCount-1);
	head.next = expr(tail);
	break;
	}
	int start = cursor;
	head = createGroup(true);
	tail = root;
	head.next = expr(tail);
	tail.next = lookbehindEnd;
	TreeInfo info = new TreeInfo();
	head.study(info);
	if (info.maxValid == false) {
	throw error("Look-behind group does not have "
	+ "an obvious maximum length");
	}
	boolean hasSupplementary = findSupplementary(start, patternLength);
	if (ch == '=') {
	head = tail = (hasSupplementary ?
	new BehindS(head, info.maxLength,
	info.minLength) :
	new Behind(head, info.maxLength,
	info.minLength));
	} else { // if (ch == '!')
	head = tail = (hasSupplementary ?
	new NotBehindS(head, info.maxLength,
	info.minLength) :
	new NotBehind(head, info.maxLength,
	info.minLength));
	}
	// clear all top-closure-nodes inside lookbehind
	if (saveTCNCount < topClosureNodes.size())
	topClosureNodes.subList(saveTCNCount, topClosureNodes.size()).clear();
	break;
	case '$':
	case '@':
	throw error("Unknown group type");
	default: // (?xxx:) inlined match flags
	unread();
	addFlag();
	ch = read();
	if (ch == ')') {
	return null; // Inline modifier only
	}
	if (ch != ':') {
	throw error("Unknown inline modifier");
	}
	head = createGroup(true);
	tail = root;
	head.next = expr(tail);
	break;
	}
	} else { // (xxx) a regular group
	capturingGroup = true;
	head = createGroup(false);
	tail = root;
	head.next = expr(tail);
	}

	accept(')', "Unclosed group");
	flags0 = save;

	// Check for quantifiers
	Node node = closure(head);
	if (node == head) { // No closure
	root = tail;
	return node; // Dual return
	}
	if (head == tail) { // Zero length assertion
	root = node;
	return node; // Dual return
	}

	// have group closure, clear all inner closure nodes from the
	// top list (no backtracking stopper optimization for inner
	if (saveTCNCount < topClosureNodes.size())
	topClosureNodes.subList(saveTCNCount, topClosureNodes.size()).clear();

	if (node instanceof Ques) {
	Ques ques = (Ques) node;
	if (ques.type == Qtype.POSSESSIVE) {
	root = node;
	return node;
	}
	tail.next = new BranchConn();
	tail = tail.next;
	if (ques.type == Qtype.GREEDY) {
	head = new Branch(head, null, tail);
	} else { // Reluctant quantifier
	head = new Branch(null, head, tail);
	}
	root = tail;
	return head;
	} else if (node instanceof Curly) {
	Curly curly = (Curly) node;
	if (curly.type == Qtype.POSSESSIVE) {
	root = node;
	return node;
	}
	// Discover if the group is deterministic
	TreeInfo info = new TreeInfo();
	if (head.study(info)) { // Deterministic
	GroupTail temp = (GroupTail) tail;
	head = root = new GroupCurly(head.next, curly.cmin,
	curly.cmax, curly.type,
	((GroupTail)tail).localIndex,
	((GroupTail)tail).groupIndex,
	capturingGroup);
	return head;
	} else { // Non-deterministic
	int temp = ((GroupHead) head).localIndex;
	Loop loop;
	if (curly.type == Qtype.GREEDY) {
	loop = new Loop(this.localCount, temp);
	// add the max_reps greedy to the top-closure-node list
	if (curly.cmax == MAX_REPS)
	topClosureNodes.add(loop);
	} else { // Reluctant Curly
	loop = new LazyLoop(this.localCount, temp);
	}
	Prolog prolog = new Prolog(loop);
	this.localCount += 1;
	loop.cmin = curly.cmin;
	loop.cmax = curly.cmax;
	loop.body = head;
	tail.next = loop;
	root = loop;
	return prolog; // Dual return
	}
	}
	throw error("Internal logic error");
	}

	/**
	* Create group head and tail nodes using double return. If the group is
	* created with anonymous true then it is a pure group and should not
	* affect group counting.
	*/
	private Node createGroup(boolean anonymous) {
	int localIndex = localCount++;
	int groupIndex = 0;
	if (!anonymous)
	groupIndex = capturingGroupCount++;
	GroupHead head = new GroupHead(localIndex);
	root = new GroupTail(localIndex, groupIndex);

	// for debug/print only, head.match does NOT need the "tail" info
	head.tail = (GroupTail)root;

	if (!anonymous && groupIndex < 10)
	groupNodes[groupIndex] = head;
	return head;
	}

	@SuppressWarnings("fallthrough")
	/**
	* Parses inlined match flags and set them appropriately.
	*/
	private void addFlag() {
	int ch = peek();
	for (;;) {
	switch (ch) {
	case 'i':
	flags0 \|= CASE_INSENSITIVE;
	break;
	case 'm':
	flags0 \|= MULTILINE;
	break;
	case 's':
	flags0 \|= DOTALL;
	break;
	case 'd':
	flags0 \|= UNIX_LINES;
	break;
	case 'u':
	flags0 \|= UNICODE_CASE;
	break;
	case 'c':
	flags0 \|= CANON_EQ;
	break;
	case 'x':
	flags0 \|= COMMENTS;
	break;
	case 'U':
	flags0 \|= (UNICODE_CHARACTER_CLASS \| UNICODE_CASE);
	break;
	case '-': // subFlag then fall through
	ch = next();
	subFlag();
	default:
	return;
	}
	ch = next();
	}
	}

	@SuppressWarnings("fallthrough")
	/**
	* Parses the second part of inlined match flags and turns off
	* flags appropriately.
	*/
	private void subFlag() {
	int ch = peek();
	for (;;) {
	switch (ch) {
	case 'i':
	flags0 &= ~CASE_INSENSITIVE;
	break;
	case 'm':
	flags0 &= ~MULTILINE;
	break;
	case 's':
	flags0 &= ~DOTALL;
	break;
	case 'd':
	flags0 &= ~UNIX_LINES;
	break;
	case 'u':
	flags0 &= ~UNICODE_CASE;
	break;
	case 'c':
	flags0 &= ~CANON_EQ;
	break;
	case 'x':
	flags0 &= ~COMMENTS;
	break;
	case 'U':
	flags0 &= ~(UNICODE_CHARACTER_CLASS \| UNICODE_CASE);
	break;
	default:
	return;
	}
	ch = next();
	}
	}

	static final int MAX_REPS = 0x7FFFFFFF;

	static enum Qtype {
	GREEDY, LAZY, POSSESSIVE, INDEPENDENT
	}

	private Node curly(Node prev, int cmin) {
	int ch = next();
	if (ch == '?') {
	next();
	return new Curly(prev, cmin, MAX_REPS, Qtype.LAZY);
	} else if (ch == '+') {
	next();
	return new Curly(prev, cmin, MAX_REPS, Qtype.POSSESSIVE);
	}
	if (prev instanceof BmpCharProperty) {
	return new BmpCharPropertyGreedy((BmpCharProperty)prev, cmin);
	} else if (prev instanceof CharProperty) {
	return new CharPropertyGreedy((CharProperty)prev, cmin);
	}
	return new Curly(prev, cmin, MAX_REPS, Qtype.GREEDY);
	}

	/**
	* Processes repetition. If the next character peeked is a quantifier
	* then new nodes must be appended to handle the repetition.
	* Prev could be a single or a group, so it could be a chain of nodes.
	*/
	private Node closure(Node prev) {
	Node atom;
	int ch = peek();
	switch (ch) {
	case '?':
	ch = next();
	if (ch == '?') {
	next();
	return new Ques(prev, Qtype.LAZY);
	} else if (ch == '+') {
	next();
	return new Ques(prev, Qtype.POSSESSIVE);
	}
	return new Ques(prev, Qtype.GREEDY);
	case '*':
	return curly(prev, 0);
	case '+':
	return curly(prev, 1);
	case '{':
	ch = temp[cursor+1];
	if (ASCII.isDigit(ch)) {
	skip();
	int cmin = 0;
	do {
	cmin = cmin * 10 + (ch - '0');
	} while (ASCII.isDigit(ch = read()));
	int cmax = cmin;
	if (ch == ',') {
	ch = read();
	cmax = MAX_REPS;
	if (ch != '}') {
	cmax = 0;
	while (ASCII.isDigit(ch)) {
	cmax = cmax * 10 + (ch - '0');
	ch = read();
	}
	}
	}
	if (ch != '}')
	throw error("Unclosed counted closure");
	if (((cmin) \| (cmax) \| (cmax - cmin)) < 0)
	throw error("Illegal repetition range");
	Curly curly;
	ch = peek();
	if (ch == '?') {
	next();
	curly = new Curly(prev, cmin, cmax, Qtype.LAZY);
	} else if (ch == '+') {
	next();
	curly = new Curly(prev, cmin, cmax, Qtype.POSSESSIVE);
	} else {
	curly = new Curly(prev, cmin, cmax, Qtype.GREEDY);
	}
	return curly;
	} else {
	throw error("Illegal repetition");
	}
	default:
	return prev;
	}
	}

	/**
	* Utility method for parsing control escape sequences.
	*/
	private int c() {
	if (cursor < patternLength) {
	return read() ^ 64;
	}
	throw error("Illegal control escape sequence");
	}

	/**
	* Utility method for parsing octal escape sequences.
	*/
	private int o() {
	int n = read();
	if (((n-'0')\|('7'-n)) >= 0) {
	int m = read();
	if (((m-'0')\|('7'-m)) >= 0) {
	int o = read();
	if ((((o-'0')\|('7'-o)) >= 0) && (((n-'0')\|('3'-n)) >= 0)) {
	return (n - '0') * 64 + (m - '0') * 8 + (o - '0');
	}
	unread();
	return (n - '0') * 8 + (m - '0');
	}
	unread();
	return (n - '0');
	}
	throw error("Illegal octal escape sequence");
	}

	/**
	* Utility method for parsing hexadecimal escape sequences.
	*/
	private int x() {
	int n = read();
	if (ASCII.isHexDigit(n)) {
	int m = read();
	if (ASCII.isHexDigit(m)) {
	return ASCII.toDigit(n) * 16 + ASCII.toDigit(m);
	}
	} else if (n == '{' && ASCII.isHexDigit(peek())) {
	int ch = 0;
	while (ASCII.isHexDigit(n = read())) {
	ch = (ch << 4) + ASCII.toDigit(n);
	if (ch > Character.MAX_CODE_POINT)
	throw error("Hexadecimal codepoint is too big");
	}
	if (n != '}')
	throw error("Unclosed hexadecimal escape sequence");
	return ch;
	}
	throw error("Illegal hexadecimal escape sequence");
	}

	/**
	* Utility method for parsing unicode escape sequences.
	*/
	private int cursor() {
	return cursor;
	}

	private void setcursor(int pos) {
	cursor = pos;
	}

	private int uxxxx() {
	int n = 0;
	for (int i = 0; i < 4; i++) {
	int ch = read();
	if (!ASCII.isHexDigit(ch)) {
	throw error("Illegal Unicode escape sequence");
	}
	n = n * 16 + ASCII.toDigit(ch);
	}
	return n;
	}

	private int u() {
	int n = uxxxx();
	if (Character.isHighSurrogate((char)n)) {
	int cur = cursor();
	if (read() == '\\' && read() == 'u') {
	int n2 = uxxxx();
	if (Character.isLowSurrogate((char)n2))
	return Character.toCodePoint((char)n, (char)n2);
	}
	setcursor(cur);
	}
	return n;
	}

	private int N() {
	if (read() == '{') {
	int i = cursor;
	while (cursor < patternLength && read() != '}') {}
	if (cursor > patternLength)
	throw error("Unclosed character name escape sequence");
	String name = new String(temp, i, cursor - i - 1);
	try {
	return Character.codePointOf(name);
	} catch (IllegalArgumentException x) {
	throw error("Unknown character name [" + name + "]");
	}
	}
	throw error("Illegal character name escape sequence");
	}

	//
	// Utility methods for code point support
	//
	private static final int countChars(CharSequence seq, int index,
	int lengthInCodePoints) {
	// optimization
	if (lengthInCodePoints == 1 && !Character.isHighSurrogate(seq.charAt(index))) {
	assert (index >= 0 && index < seq.length());
	return 1;
	}
	int length = seq.length();
	int x = index;
	if (lengthInCodePoints >= 0) {
	assert (index >= 0 && index < length);
	for (int i = 0; x < length && i < lengthInCodePoints; i++) {
	if (Character.isHighSurrogate(seq.charAt(x++))) {
	if (x < length && Character.isLowSurrogate(seq.charAt(x))) {
	x++;
	}
	}
	}
	return x - index;
	}

	assert (index >= 0 && index <= length);
	if (index == 0) {
	return 0;
	}
	int len = -lengthInCodePoints;
	for (int i = 0; x > 0 && i < len; i++) {
	if (Character.isLowSurrogate(seq.charAt(--x))) {
	if (x > 0 && Character.isHighSurrogate(seq.charAt(x-1))) {
	x--;
	}
	}
	}
	return index - x;
	}

	private static final int countCodePoints(CharSequence seq) {
	int length = seq.length();
	int n = 0;
	for (int i = 0; i < length; ) {
	n++;
	if (Character.isHighSurrogate(seq.charAt(i++))) {
	if (i < length && Character.isLowSurrogate(seq.charAt(i))) {
	i++;
	}
	}
	}
	return n;
	}

	/**
	* Creates a bit vector for matching Latin-1 values. A normal BitClass
	* never matches values above Latin-1, and a complemented BitClass always
	* matches values above Latin-1.
	*/
	static final class BitClass extends BmpCharProperty {
	final boolean[] bits;
	BitClass() {
	this(new boolean[256]);
	}
	private BitClass(boolean[] bits) {
	super( ch -> ch < 256 && bits[ch]);
	this.bits = bits;
	}
	BitClass add(int c, int flags) {
	assert c >= 0 && c <= 255;
	if ((flags & CASE_INSENSITIVE) != 0) {
	if (ASCII.isAscii(c)) {
	bits[ASCII.toUpper(c)] = true;
	bits[ASCII.toLower(c)] = true;
	} else if ((flags & UNICODE_CASE) != 0) {
	bits[Character.toLowerCase(c)] = true;
	bits[Character.toUpperCase(c)] = true;
	}
	}
	bits[c] = true;
	return this;
	}
	}

	/**
	* Utility method for creating a string slice matcher.
	*/
	private Node newSlice(int[] buf, int count, boolean hasSupplementary) {
	int[] tmp = new int[count];
	if (has(CASE_INSENSITIVE)) {
	if (has(UNICODE_CASE)) {
	for (int i = 0; i < count; i++) {
	tmp[i] = Character.toLowerCase(
	Character.toUpperCase(buf[i]));
	}
	return hasSupplementary? new SliceUS(tmp) : new SliceU(tmp);
	}
	for (int i = 0; i < count; i++) {
	tmp[i] = ASCII.toLower(buf[i]);
	}
	return hasSupplementary? new SliceIS(tmp) : new SliceI(tmp);
	}
	for (int i = 0; i < count; i++) {
	tmp[i] = buf[i];
	}
	return hasSupplementary ? new SliceS(tmp) : new Slice(tmp);
	}

	/**
	* The following classes are the building components of the object
	* tree that represents a compiled regular expression. The object tree
	* is made of individual elements that handle constructs in the Pattern.
	* Each type of object knows how to match its equivalent construct with
	* the match() method.
	*/

	/**
	* Base class for all node classes. Subclasses should override the match()
	* method as appropriate. This class is an accepting node, so its match()
	* always returns true.
	*/
	static class Node extends Object {
	Node next;
	Node() {
	next = Pattern.accept;
	}
	/**
	* This method implements the classic accept node.
	*/
	boolean match(Matcher matcher, int i, CharSequence seq) {
	matcher.last = i;
	matcher.groups[0] = matcher.first;
	matcher.groups[1] = matcher.last;
	return true;
	}
	/**
	* This method is good for all zero length assertions.
	*/
	boolean study(TreeInfo info) {
	if (next != null) {
	return next.study(info);
	} else {
	return info.deterministic;
	}
	}
	}

	static class LastNode extends Node {
	/**
	* This method implements the classic accept node with
	* the addition of a check to see if the match occurred
	* using all of the input.
	*/
	boolean match(Matcher matcher, int i, CharSequence seq) {
	if (matcher.acceptMode == Matcher.ENDANCHOR && i != matcher.to)
	return false;
	matcher.last = i;
	matcher.groups[0] = matcher.first;
	matcher.groups[1] = matcher.last;
	return true;
	}
	}

	/**
	* Used for REs that can start anywhere within the input string.
	* This basically tries to match repeatedly at each spot in the
	* input string, moving forward after each try. An anchored search
	* or a BnM will bypass this node completely.
	*/
	static class Start extends Node {
	int minLength;
	Start(Node node) {
	this.next = node;
	TreeInfo info = new TreeInfo();
	next.study(info);
	minLength = info.minLength;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	if (i > matcher.to - minLength) {
	matcher.hitEnd = true;
	return false;
	}
	int guard = matcher.to - minLength;
	for (; i <= guard; i++) {
	if (next.match(matcher, i, seq)) {
	matcher.first = i;
	matcher.groups[0] = matcher.first;
	matcher.groups[1] = matcher.last;
	return true;
	}
	}
	matcher.hitEnd = true;
	return false;
	}
	boolean study(TreeInfo info) {
	next.study(info);
	info.maxValid = false;
	info.deterministic = false;
	return false;
	}
	}

	/*
	* StartS supports supplementary characters, including unpaired surrogates.
	*/
	static final class StartS extends Start {
	StartS(Node node) {
	super(node);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	if (i > matcher.to - minLength) {
	matcher.hitEnd = true;
	return false;
	}
	int guard = matcher.to - minLength;
	while (i <= guard) {
	//if ((ret = next.match(matcher, i, seq)) \|\| i == guard)
	if (next.match(matcher, i, seq)) {
	matcher.first = i;
	matcher.groups[0] = matcher.first;
	matcher.groups[1] = matcher.last;
	return true;
	}
	if (i == guard)
	break;
	// Optimization to move to the next character. This is
	// faster than countChars(seq, i, 1).
	if (Character.isHighSurrogate(seq.charAt(i++))) {
	if (i < seq.length() &&
	Character.isLowSurrogate(seq.charAt(i))) {
	i++;
	}
	}
	}
	matcher.hitEnd = true;
	return false;
	}
	}

	/**
	* Node to anchor at the beginning of input. This object implements the
	* match for a \A sequence, and the caret anchor will use this if not in
	* multiline mode.
	*/
	static final class Begin extends Node {
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int fromIndex = (matcher.anchoringBounds) ?
	matcher.from : 0;
	if (i == fromIndex && next.match(matcher, i, seq)) {
	matcher.first = i;
	matcher.groups[0] = i;
	matcher.groups[1] = matcher.last;
	return true;
	} else {
	return false;
	}
	}
	}

	/**
	* Node to anchor at the end of input. This is the absolute end, so this
	* should not match at the last newline before the end as $ will.
	*/
	static final class End extends Node {
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int endIndex = (matcher.anchoringBounds) ?
	matcher.to : matcher.getTextLength();
	if (i == endIndex) {
	matcher.hitEnd = true;
	return next.match(matcher, i, seq);
	}
	return false;
	}
	}

	/**
	* Node to anchor at the beginning of a line. This is essentially the
	* object to match for the multiline ^.
	*/
	static final class Caret extends Node {
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int startIndex = matcher.from;
	int endIndex = matcher.to;
	if (!matcher.anchoringBounds) {
	startIndex = 0;
	endIndex = matcher.getTextLength();
	}
	// Perl does not match ^ at end of input even after newline
	if (i == endIndex) {
	matcher.hitEnd = true;
	return false;
	}
	if (i > startIndex) {
	char ch = seq.charAt(i-1);
	if (ch != '\n' && ch != '\r'
	&& (ch\|1) != '\u2029'
	&& ch != '\u0085' ) {
	return false;
	}
	// Should treat /r/n as one newline
	if (ch == '\r' && seq.charAt(i) == '\n')
	return false;
	}
	return next.match(matcher, i, seq);
	}
	}

	/**
	* Node to anchor at the beginning of a line when in unixdot mode.
	*/
	static final class UnixCaret extends Node {
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int startIndex = matcher.from;
	int endIndex = matcher.to;
	if (!matcher.anchoringBounds) {
	startIndex = 0;
	endIndex = matcher.getTextLength();
	}
	// Perl does not match ^ at end of input even after newline
	if (i == endIndex) {
	matcher.hitEnd = true;
	return false;
	}
	if (i > startIndex) {
	char ch = seq.charAt(i-1);
	if (ch != '\n') {
	return false;
	}
	}
	return next.match(matcher, i, seq);
	}
	}

	/**
	* Node to match the location where the last match ended.
	* This is used for the \G construct.
	*/
	static final class LastMatch extends Node {
	boolean match(Matcher matcher, int i, CharSequence seq) {
	if (i != matcher.oldLast)
	return false;
	return next.match(matcher, i, seq);
	}
	}

	/**
	* Node to anchor at the end of a line or the end of input based on the
	* multiline mode.
	*
	* When not in multiline mode, the $ can only match at the very end
	* of the input, unless the input ends in a line terminator in which
	* it matches right before the last line terminator.
	*
	* Note that \r\n is considered an atomic line terminator.
	*
	* Like ^ the $ operator matches at a position, it does not match the
	* line terminators themselves.
	*/
	static final class Dollar extends Node {
	boolean multiline;
	Dollar(boolean mul) {
	multiline = mul;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int endIndex = (matcher.anchoringBounds) ?
	matcher.to : matcher.getTextLength();
	if (!multiline) {
	if (i < endIndex - 2)
	return false;
	if (i == endIndex - 2) {
	char ch = seq.charAt(i);
	if (ch != '\r')
	return false;
	ch = seq.charAt(i + 1);
	if (ch != '\n')
	return false;
	}
	}
	// Matches before any line terminator; also matches at the
	// end of input
	// Before line terminator:
	// If multiline, we match here no matter what
	// If not multiline, fall through so that the end
	// is marked as hit; this must be a /r/n or a /n
	// at the very end so the end was hit; more input
	// could make this not match here
	if (i < endIndex) {
	char ch = seq.charAt(i);
	if (ch == '\n') {
	// No match between \r\n
	if (i > 0 && seq.charAt(i-1) == '\r')
	return false;
	if (multiline)
	return next.match(matcher, i, seq);
	} else if (ch == '\r' \|\| ch == '\u0085' \|\|
	(ch\|1) == '\u2029') {
	if (multiline)
	return next.match(matcher, i, seq);
	} else { // No line terminator, no match
	return false;
	}
	}
	// Matched at current end so hit end
	matcher.hitEnd = true;
	// If a $ matches because of end of input, then more input
	// could cause it to fail!
	matcher.requireEnd = true;
	return next.match(matcher, i, seq);
	}
	boolean study(TreeInfo info) {
	next.study(info);
	return info.deterministic;
	}
	}

	/**
	* Node to anchor at the end of a line or the end of input based on the
	* multiline mode when in unix lines mode.
	*/
	static final class UnixDollar extends Node {
	boolean multiline;
	UnixDollar(boolean mul) {
	multiline = mul;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int endIndex = (matcher.anchoringBounds) ?
	matcher.to : matcher.getTextLength();
	if (i < endIndex) {
	char ch = seq.charAt(i);
	if (ch == '\n') {
	// If not multiline, then only possible to
	// match at very end or one before end
	if (multiline == false && i != endIndex - 1)
	return false;
	// If multiline return next.match without setting
	// matcher.hitEnd
	if (multiline)
	return next.match(matcher, i, seq);
	} else {
	return false;
	}
	}
	// Matching because at the end or 1 before the end;
	// more input could change this so set hitEnd
	matcher.hitEnd = true;
	// If a $ matches because of end of input, then more input
	// could cause it to fail!
	matcher.requireEnd = true;
	return next.match(matcher, i, seq);
	}
	boolean study(TreeInfo info) {
	next.study(info);
	return info.deterministic;
	}
	}

	/**
	* Node class that matches a Unicode line ending '\R'
	*/
	static final class LineEnding extends Node {
	boolean match(Matcher matcher, int i, CharSequence seq) {
	// (u+000Du+000A\|[u+000Au+000Bu+000Cu+000Du+0085u+2028u+2029])
	if (i < matcher.to) {
	int ch = seq.charAt(i);
	if (ch == 0x0A \|\| ch == 0x0B \|\| ch == 0x0C \|\|
	ch == 0x85 \|\| ch == 0x2028 \|\| ch == 0x2029)
	return next.match(matcher, i + 1, seq);
	if (ch == 0x0D) {
	i++;
	if (i < matcher.to) {
	if (seq.charAt(i) == 0x0A &&
	next.match(matcher, i + 1, seq)) {
	return true;
	}
	} else {
	matcher.hitEnd = true;
	}
	return next.match(matcher, i, seq);
	}
	} else {
	matcher.hitEnd = true;
	}
	return false;
	}
	boolean study(TreeInfo info) {
	info.minLength++;
	info.maxLength += 2;
	return next.study(info);
	}
	}

	/**
	* Abstract node class to match one character satisfying some
	* boolean property.
	*/
	static class CharProperty extends Node {
	CharPredicate predicate;

	CharProperty (CharPredicate predicate) {
	this.predicate = predicate;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	if (i < matcher.to) {
	int ch = Character.codePointAt(seq, i);
	return predicate.is(ch) &&
	next.match(matcher, i + Character.charCount(ch), seq);
	} else {
	matcher.hitEnd = true;
	return false;
	}
	}
	boolean study(TreeInfo info) {
	info.minLength++;
	info.maxLength++;
	return next.study(info);
	}
	}

	/**
	* Optimized version of CharProperty that works only for
	* properties never satisfied by Supplementary characters.
	*/
	private static class BmpCharProperty extends CharProperty {
	BmpCharProperty (BmpCharPredicate predicate) {
	super(predicate);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	if (i < matcher.to) {
	return predicate.is(seq.charAt(i)) &&
	next.match(matcher, i + 1, seq);
	} else {
	matcher.hitEnd = true;
	return false;
	}
	}
	}

	private static class NFCCharProperty extends Node {
	CharPredicate predicate;
	NFCCharProperty (CharPredicate predicate) {
	this.predicate = predicate;
	}

	boolean match(Matcher matcher, int i, CharSequence seq) {
	if (i < matcher.to) {
	int ch0 = Character.codePointAt(seq, i);
	int n = Character.charCount(ch0);
	int j = i + n;
	while (j < matcher.to) {
	int ch1 = Character.codePointAt(seq, j);
	if (Grapheme.isBoundary(ch0, ch1))
	break;
	ch0 = ch1;
	j += Character.charCount(ch1);
	}
	if (i + n == j) { // single, assume nfc cp
	if (predicate.is(ch0))
	return next.match(matcher, j, seq);
	} else {
	while (i + n < j) {
	String nfc = Normalizer.normalize(
	seq.toString().substring(i, j), Normalizer.Form.NFC);
	if (nfc.codePointCount(0, nfc.length()) == 1) {
	if (predicate.is(nfc.codePointAt(0)) &&
	next.match(matcher, j, seq)) {
	return true;
	}
	}

	ch0 = Character.codePointBefore(seq, j);
	j -= Character.charCount(ch0);
	}
	}
	if (j < matcher.to)
	return false;
	}
	matcher.hitEnd = true;
	return false;
	}

	boolean study(TreeInfo info) {
	info.minLength++;
	info.deterministic = false;
	return next.study(info);
	}
	}

	/**
	* Node class that matches an unicode extended grapheme cluster
	*/
	static class XGrapheme extends Node {
	boolean match(Matcher matcher, int i, CharSequence seq) {
	if (i < matcher.to) {
	int ch0 = Character.codePointAt(seq, i);
	i += Character.charCount(ch0);
	while (i < matcher.to) {
	int ch1 = Character.codePointAt(seq, i);
	if (Grapheme.isBoundary(ch0, ch1))
	break;
	ch0 = ch1;
	i += Character.charCount(ch1);
	}
	return next.match(matcher, i, seq);
	}
	matcher.hitEnd = true;
	return false;
	}

	boolean study(TreeInfo info) {
	info.minLength++;
	info.deterministic = false;
	return next.study(info);
	}
	}

	/**
	* Node class that handles grapheme boundaries
	*/
	static class GraphemeBound extends Node {
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int startIndex = matcher.from;
	int endIndex = matcher.to;
	if (matcher.transparentBounds) {
	startIndex = 0;
	endIndex = matcher.getTextLength();
	}
	if (i == startIndex) {
	return next.match(matcher, i, seq);
	}
	if (i < endIndex) {
	if (Character.isSurrogatePair(seq.charAt(i-1), seq.charAt(i)) \|\|
	!Grapheme.isBoundary(Character.codePointBefore(seq, i),
	Character.codePointAt(seq, i))) {
	return false;
	}
	} else {
	matcher.hitEnd = true;
	matcher.requireEnd = true;
	}
	return next.match(matcher, i, seq);
	}
	}

	/**
	* Base class for all Slice nodes
	*/
	static class SliceNode extends Node {
	int[] buffer;
	SliceNode(int[] buf) {
	buffer = buf;
	}
	boolean study(TreeInfo info) {
	info.minLength += buffer.length;
	info.maxLength += buffer.length;
	return next.study(info);
	}
	}

	/**
	* Node class for a case sensitive/BMP-only sequence of literal
	* characters.
	*/
	static class Slice extends SliceNode {
	Slice(int[] buf) {
	super(buf);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int[] buf = buffer;
	int len = buf.length;
	for (int j=0; j<len; j++) {
	if ((i+j) >= matcher.to) {
	matcher.hitEnd = true;
	return false;
	}
	if (buf[j] != seq.charAt(i+j))
	return false;
	}
	return next.match(matcher, i+len, seq);
	}
	}

	/**
	* Node class for a case_insensitive/BMP-only sequence of literal
	* characters.
	*/
	static class SliceI extends SliceNode {
	SliceI(int[] buf) {
	super(buf);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int[] buf = buffer;
	int len = buf.length;
	for (int j=0; j<len; j++) {
	if ((i+j) >= matcher.to) {
	matcher.hitEnd = true;
	return false;
	}
	int c = seq.charAt(i+j);
	if (buf[j] != c &&
	buf[j] != ASCII.toLower(c))
	return false;
	}
	return next.match(matcher, i+len, seq);
	}
	}

	/**
	* Node class for a unicode_case_insensitive/BMP-only sequence of
	* literal characters. Uses unicode case folding.
	*/
	static final class SliceU extends SliceNode {
	SliceU(int[] buf) {
	super(buf);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int[] buf = buffer;
	int len = buf.length;
	for (int j=0; j<len; j++) {
	if ((i+j) >= matcher.to) {
	matcher.hitEnd = true;
	return false;
	}
	int c = seq.charAt(i+j);
	if (buf[j] != c &&
	buf[j] != Character.toLowerCase(Character.toUpperCase(c)))
	return false;
	}
	return next.match(matcher, i+len, seq);
	}
	}

	/**
	* Node class for a case sensitive sequence of literal characters
	* including supplementary characters.
	*/
	static final class SliceS extends Slice {
	SliceS(int[] buf) {
	super(buf);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int[] buf = buffer;
	int x = i;
	for (int j = 0; j < buf.length; j++) {
	if (x >= matcher.to) {
	matcher.hitEnd = true;
	return false;
	}
	int c = Character.codePointAt(seq, x);
	if (buf[j] != c)
	return false;
	x += Character.charCount(c);
	if (x > matcher.to) {
	matcher.hitEnd = true;
	return false;
	}
	}
	return next.match(matcher, x, seq);
	}
	}

	/**
	* Node class for a case insensitive sequence of literal characters
	* including supplementary characters.
	*/
	static class SliceIS extends SliceNode {
	SliceIS(int[] buf) {
	super(buf);
	}
	int toLower(int c) {
	return ASCII.toLower(c);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int[] buf = buffer;
	int x = i;
	for (int j = 0; j < buf.length; j++) {
	if (x >= matcher.to) {
	matcher.hitEnd = true;
	return false;
	}
	int c = Character.codePointAt(seq, x);
	if (buf[j] != c && buf[j] != toLower(c))
	return false;
	x += Character.charCount(c);
	if (x > matcher.to) {
	matcher.hitEnd = true;
	return false;
	}
	}
	return next.match(matcher, x, seq);
	}
	}

	/**
	* Node class for a case insensitive sequence of literal characters.
	* Uses unicode case folding.
	*/
	static final class SliceUS extends SliceIS {
	SliceUS(int[] buf) {
	super(buf);
	}
	int toLower(int c) {
	return Character.toLowerCase(Character.toUpperCase(c));
	}
	}

	/**
	* The 0 or 1 quantifier. This one class implements all three types.
	*/
	static final class Ques extends Node {
	Node atom;
	Qtype type;
	Ques(Node node, Qtype type) {
	this.atom = node;
	this.type = type;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	switch (type) {
	case GREEDY:
	return (atom.match(matcher, i, seq) && next.match(matcher, matcher.last, seq))
	\|\| next.match(matcher, i, seq);
	case LAZY:
	return next.match(matcher, i, seq)
	\|\| (atom.match(matcher, i, seq) && next.match(matcher, matcher.last, seq));
	case POSSESSIVE:
	if (atom.match(matcher, i, seq)) i = matcher.last;
	return next.match(matcher, i, seq);
	default:
	return atom.match(matcher, i, seq) && next.match(matcher, matcher.last, seq);
	}
	}
	boolean study(TreeInfo info) {
	if (type != Qtype.INDEPENDENT) {
	int minL = info.minLength;
	atom.study(info);
	info.minLength = minL;
	info.deterministic = false;
	return next.study(info);
	} else {
	atom.study(info);
	return next.study(info);
	}
	}
	}

	/**
	* Handles the greedy style repetition with the minimum either be
	* 0 or 1 and the maximum be MAX_REPS, for * and + quantifier.
	*/
	static class CharPropertyGreedy extends Node {
	final CharPredicate predicate;
	final int cmin;

	CharPropertyGreedy(CharProperty cp, int cmin) {
	this.predicate = cp.predicate;
	this.cmin = cmin;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int n = 0;
	int to = matcher.to;
	// greedy, all the way down
	while (i < to) {
	int ch = Character.codePointAt(seq, i);
	if (!predicate.is(ch))
	break;
	i += Character.charCount(ch);
	n++;
	}
	if (i >= to) {
	matcher.hitEnd = true;
	}
	while (n >= cmin) {
	if (next.match(matcher, i, seq))
	return true;
	if (n == cmin)
	return false;
	// backing off if match fails
	int ch = Character.codePointBefore(seq, i);
	i -= Character.charCount(ch);
	n--;
	}
	return false;
	}

	boolean study(TreeInfo info) {
	info.minLength += cmin;
	if (info.maxValid) {
	info.maxLength += MAX_REPS;
	}
	info.deterministic = false;
	return next.study(info);
	}
	}

	static final class BmpCharPropertyGreedy extends CharPropertyGreedy {

	BmpCharPropertyGreedy(BmpCharProperty bcp, int cmin) {
	super(bcp, cmin);
	}

	boolean match(Matcher matcher, int i, CharSequence seq) {
	int n = 0;
	int to = matcher.to;
	while (i < to && predicate.is(seq.charAt(i))) {
	i++; n++;
	}
	if (i >= to) {
	matcher.hitEnd = true;
	}
	while (n >= cmin) {
	if (next.match(matcher, i, seq))
	return true;
	i--; n--; // backing off if match fails
	}
	return false;
	}
	}

	/**
	* Handles the curly-brace style repetition with a specified minimum and
	* maximum occurrences. The * quantifier is handled as a special case.
	* This class handles the three types.
	*/
	static final class Curly extends Node {
	Node atom;
	Qtype type;
	int cmin;
	int cmax;

	Curly(Node node, int cmin, int cmax, Qtype type) {
	this.atom = node;
	this.type = type;
	this.cmin = cmin;
	this.cmax = cmax;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int j;
	for (j = 0; j < cmin; j++) {
	if (atom.match(matcher, i, seq)) {
	i = matcher.last;
	continue;
	}
	return false;
	}
	if (type == Qtype.GREEDY)
	return match0(matcher, i, j, seq);
	else if (type == Qtype.LAZY)
	return match1(matcher, i, j, seq);
	else
	return match2(matcher, i, j, seq);
	}
	// Greedy match.
	// i is the index to start matching at
	// j is the number of atoms that have matched
	boolean match0(Matcher matcher, int i, int j, CharSequence seq) {
	if (j >= cmax) {
	// We have matched the maximum... continue with the rest of
	// the regular expression
	return next.match(matcher, i, seq);
	}
	int backLimit = j;
	while (atom.match(matcher, i, seq)) {
	// k is the length of this match
	int k = matcher.last - i;
	if (k == 0) // Zero length match
	break;
	// Move up index and number matched
	i = matcher.last;
	j++;
	// We are greedy so match as many as we can
	while (j < cmax) {
	if (!atom.match(matcher, i, seq))
	break;
	if (i + k != matcher.last) {
	if (match0(matcher, matcher.last, j+1, seq))
	return true;
	break;
	}
	i += k;
	j++;
	}
	// Handle backing off if match fails
	while (j >= backLimit) {
	if (next.match(matcher, i, seq))
	return true;
	i -= k;
	j--;
	}
	return false;
	}
	return next.match(matcher, i, seq);
	}
	// Reluctant match. At this point, the minimum has been satisfied.
	// i is the index to start matching at
	// j is the number of atoms that have matched
	boolean match1(Matcher matcher, int i, int j, CharSequence seq) {
	for (;;) {
	// Try finishing match without consuming any more
	if (next.match(matcher, i, seq))
	return true;
	// At the maximum, no match found
	if (j >= cmax)
	return false;
	// Okay, must try one more atom
	if (!atom.match(matcher, i, seq))
	return false;
	// If we haven't moved forward then must break out
	if (i == matcher.last)
	return false;
	// Move up index and number matched
	i = matcher.last;
	j++;
	}
	}
	boolean match2(Matcher matcher, int i, int j, CharSequence seq) {
	for (; j < cmax; j++) {
	if (!atom.match(matcher, i, seq))
	break;
	if (i == matcher.last)
	break;
	i = matcher.last;
	}
	return next.match(matcher, i, seq);
	}
	boolean study(TreeInfo info) {
	// Save original info
	int minL = info.minLength;
	int maxL = info.maxLength;
	boolean maxV = info.maxValid;
	boolean detm = info.deterministic;
	info.reset();

	atom.study(info);

	int temp = info.minLength * cmin + minL;
	if (temp < minL) {
	temp = 0xFFFFFFF; // arbitrary large number
	}
	info.minLength = temp;

	if (maxV & info.maxValid) {
	temp = info.maxLength * cmax + maxL;
	info.maxLength = temp;
	if (temp < maxL) {
	info.maxValid = false;
	}
	} else {
	info.maxValid = false;
	}

	if (info.deterministic && cmin == cmax)
	info.deterministic = detm;
	else
	info.deterministic = false;
	return next.study(info);
	}
	}

	/**
	* Handles the curly-brace style repetition with a specified minimum and
	* maximum occurrences in deterministic cases. This is an iterative
	* optimization over the Prolog and Loop system which would handle this
	* in a recursive way. The * quantifier is handled as a special case.
	* If capture is true then this class saves group settings and ensures
	* that groups are unset when backing off of a group match.
	*/
	static final class GroupCurly extends Node {
	Node atom;
	Qtype type;
	int cmin;
	int cmax;
	int localIndex;
	int groupIndex;
	boolean capture;

	GroupCurly(Node node, int cmin, int cmax, Qtype type, int local,
	int group, boolean capture) {
	this.atom = node;
	this.type = type;
	this.cmin = cmin;
	this.cmax = cmax;
	this.localIndex = local;
	this.groupIndex = group;
	this.capture = capture;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int[] groups = matcher.groups;
	int[] locals = matcher.locals;
	int save0 = locals[localIndex];
	int save1 = 0;
	int save2 = 0;

	if (capture) {
	save1 = groups[groupIndex];
	save2 = groups[groupIndex+1];
	}

	// Notify GroupTail there is no need to setup group info
	// because it will be set here
	locals[localIndex] = -1;

	boolean ret = true;
	for (int j = 0; j < cmin; j++) {
	if (atom.match(matcher, i, seq)) {
	if (capture) {
	groups[groupIndex] = i;
	groups[groupIndex+1] = matcher.last;
	}
	i = matcher.last;
	} else {
	ret = false;
	break;
	}
	}
	if (ret) {
	if (type == Qtype.GREEDY) {
	ret = match0(matcher, i, cmin, seq);
	} else if (type == Qtype.LAZY) {
	ret = match1(matcher, i, cmin, seq);
	} else {
	ret = match2(matcher, i, cmin, seq);
	}
	}
	if (!ret) {
	locals[localIndex] = save0;
	if (capture) {
	groups[groupIndex] = save1;
	groups[groupIndex+1] = save2;
	}
	}
	return ret;
	}
	// Aggressive group match
	boolean match0(Matcher matcher, int i, int j, CharSequence seq) {
	// don't back off passing the starting "j"
	int min = j;
	int[] groups = matcher.groups;
	int save0 = 0;
	int save1 = 0;
	if (capture) {
	save0 = groups[groupIndex];
	save1 = groups[groupIndex+1];
	}
	for (;;) {
	if (j >= cmax)
	break;
	if (!atom.match(matcher, i, seq))
	break;
	int k = matcher.last - i;
	if (k <= 0) {
	if (capture) {
	groups[groupIndex] = i;
	groups[groupIndex+1] = i + k;
	}
	i = i + k;
	break;
	}
	for (;;) {
	if (capture) {
	groups[groupIndex] = i;
	groups[groupIndex+1] = i + k;
	}
	i = i + k;
	if (++j >= cmax)
	break;
	if (!atom.match(matcher, i, seq))
	break;
	if (i + k != matcher.last) {
	if (match0(matcher, i, j, seq))
	return true;
	break;
	}
	}
	while (j > min) {
	if (next.match(matcher, i, seq)) {
	if (capture) {
	groups[groupIndex+1] = i;
	groups[groupIndex] = i - k;
	}
	return true;
	}
	// backing off
	i = i - k;
	if (capture) {
	groups[groupIndex+1] = i;
	groups[groupIndex] = i - k;
	}
	j--;

	}
	break;
	}
	if (capture) {
	groups[groupIndex] = save0;
	groups[groupIndex+1] = save1;
	}
	return next.match(matcher, i, seq);
	}
	// Reluctant matching
	boolean match1(Matcher matcher, int i, int j, CharSequence seq) {
	for (;;) {
	if (next.match(matcher, i, seq))
	return true;
	if (j >= cmax)
	return false;
	if (!atom.match(matcher, i, seq))
	return false;
	if (i == matcher.last)
	return false;
	if (capture) {
	matcher.groups[groupIndex] = i;
	matcher.groups[groupIndex+1] = matcher.last;
	}
	i = matcher.last;
	j++;
	}
	}
	// Possessive matching
	boolean match2(Matcher matcher, int i, int j, CharSequence seq) {
	for (; j < cmax; j++) {
	if (!atom.match(matcher, i, seq)) {
	break;
	}
	if (capture) {
	matcher.groups[groupIndex] = i;
	matcher.groups[groupIndex+1] = matcher.last;
	}
	if (i == matcher.last) {
	break;
	}
	i = matcher.last;
	}
	return next.match(matcher, i, seq);
	}
	boolean study(TreeInfo info) {
	// Save original info
	int minL = info.minLength;
	int maxL = info.maxLength;
	boolean maxV = info.maxValid;
	boolean detm = info.deterministic;
	info.reset();

	atom.study(info);

	int temp = info.minLength * cmin + minL;
	if (temp < minL) {
	temp = 0xFFFFFFF; // Arbitrary large number
	}
	info.minLength = temp;

	if (maxV & info.maxValid) {
	temp = info.maxLength * cmax + maxL;
	info.maxLength = temp;
	if (temp < maxL) {
	info.maxValid = false;
	}
	} else {
	info.maxValid = false;
	}

	if (info.deterministic && cmin == cmax) {
	info.deterministic = detm;
	} else {
	info.deterministic = false;
	}
	return next.study(info);
	}
	}

	/**
	* A Guard node at the end of each atom node in a Branch. It
	* serves the purpose of chaining the "match" operation to
	* "next" but not the "study", so we can collect the TreeInfo
	* of each atom node without including the TreeInfo of the
	* "next".
	*/
	static final class BranchConn extends Node {
	BranchConn() {};
	boolean match(Matcher matcher, int i, CharSequence seq) {
	return next.match(matcher, i, seq);
	}
	boolean study(TreeInfo info) {
	return info.deterministic;
	}
	}

	/**
	* Handles the branching of alternations. Note this is also used for
	* the ? quantifier to branch between the case where it matches once
	* and where it does not occur.
	*/
	static final class Branch extends Node {
	Node[] atoms = new Node[2];
	int size = 2;
	Node conn;
	Branch(Node first, Node second, Node branchConn) {
	conn = branchConn;
	atoms[0] = first;
	atoms[1] = second;
	}

	void add(Node node) {
	if (size >= atoms.length) {
	Node[] tmp = new Node[atoms.length*2];
	System.arraycopy(atoms, 0, tmp, 0, atoms.length);
	atoms = tmp;
	}
	atoms[size++] = node;
	}

	boolean match(Matcher matcher, int i, CharSequence seq) {
	for (int n = 0; n < size; n++) {
	if (atoms[n] == null) {
	if (conn.next.match(matcher, i, seq))
	return true;
	} else if (atoms[n].match(matcher, i, seq)) {
	return true;
	}
	}
	return false;
	}

	boolean study(TreeInfo info) {
	int minL = info.minLength;
	int maxL = info.maxLength;
	boolean maxV = info.maxValid;

	int minL2 = Integer.MAX_VALUE; //arbitrary large enough num
	int maxL2 = -1;
	for (int n = 0; n < size; n++) {
	info.reset();
	if (atoms[n] != null)
	atoms[n].study(info);
	minL2 = Math.min(minL2, info.minLength);
	maxL2 = Math.max(maxL2, info.maxLength);
	maxV = (maxV & info.maxValid);
	}

	minL += minL2;
	maxL += maxL2;

	info.reset();
	conn.next.study(info);

	info.minLength += minL;
	info.maxLength += maxL;
	info.maxValid &= maxV;
	info.deterministic = false;
	return false;
	}
	}

	/**
	* The GroupHead saves the location where the group begins in the locals
	* and restores them when the match is done.
	*
	* The matchRef is used when a reference to this group is accessed later
	* in the expression. The locals will have a negative value in them to
	* indicate that we do not want to unset the group if the reference
	* doesn't match.
	*/
	static final class GroupHead extends Node {
	int localIndex;
	GroupTail tail; // for debug/print only, match does not need to know
	GroupHead(int localCount) {
	localIndex = localCount;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int save = matcher.locals[localIndex];
	matcher.locals[localIndex] = i;
	boolean ret = next.match(matcher, i, seq);
	matcher.locals[localIndex] = save;
	return ret;
	}
	boolean matchRef(Matcher matcher, int i, CharSequence seq) {
	int save = matcher.locals[localIndex];
	matcher.locals[localIndex] = ~i; // HACK
	boolean ret = next.match(matcher, i, seq);
	matcher.locals[localIndex] = save;
	return ret;
	}
	}

	/**
	* Recursive reference to a group in the regular expression. It calls
	* matchRef because if the reference fails to match we would not unset
	* the group.
	*/
	static final class GroupRef extends Node {
	GroupHead head;
	GroupRef(GroupHead head) {
	this.head = head;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	return head.matchRef(matcher, i, seq)
	&& next.match(matcher, matcher.last, seq);
	}
	boolean study(TreeInfo info) {
	info.maxValid = false;
	info.deterministic = false;
	return next.study(info);
	}
	}

	/**
	* The GroupTail handles the setting of group beginning and ending
	* locations when groups are successfully matched. It must also be able to
	* unset groups that have to be backed off of.
	*
	* The GroupTail node is also used when a previous group is referenced,
	* and in that case no group information needs to be set.
	*/
	static final class GroupTail extends Node {
	int localIndex;
	int groupIndex;
	GroupTail(int localCount, int groupCount) {
	localIndex = localCount;
	groupIndex = groupCount + groupCount;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int tmp = matcher.locals[localIndex];
	if (tmp >= 0) { // This is the normal group case.
	// Save the group so we can unset it if it
	// backs off of a match.
	int groupStart = matcher.groups[groupIndex];
	int groupEnd = matcher.groups[groupIndex+1];

	matcher.groups[groupIndex] = tmp;
	matcher.groups[groupIndex+1] = i;
	if (next.match(matcher, i, seq)) {
	return true;
	}
	matcher.groups[groupIndex] = groupStart;
	matcher.groups[groupIndex+1] = groupEnd;
	return false;
	} else {
	// This is a group reference case. We don't need to save any
	// group info because it isn't really a group.
	matcher.last = i;
	return true;
	}
	}
	}

	/**
	* This sets up a loop to handle a recursive quantifier structure.
	*/
	static final class Prolog extends Node {
	Loop loop;
	Prolog(Loop loop) {
	this.loop = loop;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	return loop.matchInit(matcher, i, seq);
	}
	boolean study(TreeInfo info) {
	return loop.study(info);
	}
	}

	/**
	* Handles the repetition count for a greedy Curly. The matchInit
	* is called from the Prolog to save the index of where the group
	* beginning is stored. A zero length group check occurs in the
	* normal match but is skipped in the matchInit.
	*/
	static class Loop extends Node {
	Node body;
	int countIndex; // local count index in matcher locals
	int beginIndex; // group beginning index
	int cmin, cmax;
	int posIndex;
	Loop(int countIndex, int beginIndex) {
	this.countIndex = countIndex;
	this.beginIndex = beginIndex;
	this.posIndex = -1;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	// Avoid infinite loop in zero-length case.
	if (i > matcher.locals[beginIndex]) {
	int count = matcher.locals[countIndex];

	// This block is for before we reach the minimum
	// iterations required for the loop to match
	if (count < cmin) {
	matcher.locals[countIndex] = count + 1;
	boolean b = body.match(matcher, i, seq);
	// If match failed we must backtrack, so
	// the loop count should NOT be incremented
	if (!b)
	matcher.locals[countIndex] = count;
	// Return success or failure since we are under
	// minimum
	return b;
	}
	// This block is for after we have the minimum
	// iterations required for the loop to match
	if (count < cmax) {
	// Let's check if we have already tried and failed
	// at this starting position "i" in the past.
	// If yes, then just return false wihtout trying
	// again, to stop the exponential backtracking.
	if (posIndex != -1 &&
	matcher.localsPos[posIndex].contains(i)) {
	return next.match(matcher, i, seq);
	}
	matcher.locals[countIndex] = count + 1;
	boolean b = body.match(matcher, i, seq);
	// If match failed we must backtrack, so
	// the loop count should NOT be incremented
	if (b)
	return true;
	matcher.locals[countIndex] = count;
	// save the failed position
	if (posIndex != -1) {
	matcher.localsPos[posIndex].add(i);
	}
	}
	}
	return next.match(matcher, i, seq);
	}
	boolean matchInit(Matcher matcher, int i, CharSequence seq) {
	int save = matcher.locals[countIndex];
	boolean ret = false;
	if (posIndex != -1 && matcher.localsPos[posIndex] == null) {
	matcher.localsPos[posIndex] = new IntHashSet();
	}
	if (0 < cmin) {
	matcher.locals[countIndex] = 1;
	ret = body.match(matcher, i, seq);
	} else if (0 < cmax) {
	matcher.locals[countIndex] = 1;
	ret = body.match(matcher, i, seq);
	if (ret == false)
	ret = next.match(matcher, i, seq);
	} else {
	ret = next.match(matcher, i, seq);
	}
	matcher.locals[countIndex] = save;
	return ret;
	}
	boolean study(TreeInfo info) {
	info.maxValid = false;
	info.deterministic = false;
	return false;
	}
	}

	/**
	* Handles the repetition count for a reluctant Curly. The matchInit
	* is called from the Prolog to save the index of where the group
	* beginning is stored. A zero length group check occurs in the
	* normal match but is skipped in the matchInit.
	*/
	static final class LazyLoop extends Loop {
	LazyLoop(int countIndex, int beginIndex) {
	super(countIndex, beginIndex);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	// Check for zero length group
	if (i > matcher.locals[beginIndex]) {
	int count = matcher.locals[countIndex];
	if (count < cmin) {
	matcher.locals[countIndex] = count + 1;
	boolean result = body.match(matcher, i, seq);
	// If match failed we must backtrack, so
	// the loop count should NOT be incremented
	if (!result)
	matcher.locals[countIndex] = count;
	return result;
	}
	if (next.match(matcher, i, seq))
	return true;
	if (count < cmax) {
	matcher.locals[countIndex] = count + 1;
	boolean result = body.match(matcher, i, seq);
	// If match failed we must backtrack, so
	// the loop count should NOT be incremented
	if (!result)
	matcher.locals[countIndex] = count;
	return result;
	}
	return false;
	}
	return next.match(matcher, i, seq);
	}
	boolean matchInit(Matcher matcher, int i, CharSequence seq) {
	int save = matcher.locals[countIndex];
	boolean ret = false;
	if (0 < cmin) {
	matcher.locals[countIndex] = 1;
	ret = body.match(matcher, i, seq);
	} else if (next.match(matcher, i, seq)) {
	ret = true;
	} else if (0 < cmax) {
	matcher.locals[countIndex] = 1;
	ret = body.match(matcher, i, seq);
	}
	matcher.locals[countIndex] = save;
	return ret;
	}
	boolean study(TreeInfo info) {
	info.maxValid = false;
	info.deterministic = false;
	return false;
	}
	}

	/**
	* Refers to a group in the regular expression. Attempts to match
	* whatever the group referred to last matched.
	*/
	static class BackRef extends Node {
	int groupIndex;
	BackRef(int groupCount) {
	super();
	groupIndex = groupCount + groupCount;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int j = matcher.groups[groupIndex];
	int k = matcher.groups[groupIndex+1];

	int groupSize = k - j;
	// If the referenced group didn't match, neither can this
	if (j < 0)
	return false;

	// If there isn't enough input left no match
	if (i + groupSize > matcher.to) {
	matcher.hitEnd = true;
	return false;
	}
	// Check each new char to make sure it matches what the group
	// referenced matched last time around
	for (int index=0; index<groupSize; index++)
	if (seq.charAt(i+index) != seq.charAt(j+index))
	return false;

	return next.match(matcher, i+groupSize, seq);
	}
	boolean study(TreeInfo info) {
	info.maxValid = false;
	return next.study(info);
	}
	}

	static class CIBackRef extends Node {
	int groupIndex;
	boolean doUnicodeCase;
	CIBackRef(int groupCount, boolean doUnicodeCase) {
	super();
	groupIndex = groupCount + groupCount;
	this.doUnicodeCase = doUnicodeCase;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int j = matcher.groups[groupIndex];
	int k = matcher.groups[groupIndex+1];

	int groupSize = k - j;

	// If the referenced group didn't match, neither can this
	if (j < 0)
	return false;

	// If there isn't enough input left no match
	if (i + groupSize > matcher.to) {
	matcher.hitEnd = true;
	return false;
	}

	// Check each new char to make sure it matches what the group
	// referenced matched last time around
	int x = i;
	for (int index=0; index<groupSize; index++) {
	int c1 = Character.codePointAt(seq, x);
	int c2 = Character.codePointAt(seq, j);
	if (c1 != c2) {
	if (doUnicodeCase) {
	int cc1 = Character.toUpperCase(c1);
	int cc2 = Character.toUpperCase(c2);
	if (cc1 != cc2 &&
	Character.toLowerCase(cc1) !=
	Character.toLowerCase(cc2))
	return false;
	} else {
	if (ASCII.toLower(c1) != ASCII.toLower(c2))
	return false;
	}
	}
	x += Character.charCount(c1);
	j += Character.charCount(c2);
	}

	return next.match(matcher, i+groupSize, seq);
	}
	boolean study(TreeInfo info) {
	info.maxValid = false;
	return next.study(info);
	}
	}

	/**
	* Searches until the next instance of its atom. This is useful for
	* finding the atom efficiently without passing an instance of it
	* (greedy problem) and without a lot of wasted search time (reluctant
	* problem).
	*/
	static final class First extends Node {
	Node atom;
	First(Node node) {
	this.atom = BnM.optimize(node);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	if (atom instanceof BnM) {
	return atom.match(matcher, i, seq)
	&& next.match(matcher, matcher.last, seq);
	}
	for (;;) {
	if (i > matcher.to) {
	matcher.hitEnd = true;
	return false;
	}
	if (atom.match(matcher, i, seq)) {
	return next.match(matcher, matcher.last, seq);
	}
	i += countChars(seq, i, 1);
	matcher.first++;
	}
	}
	boolean study(TreeInfo info) {
	atom.study(info);
	info.maxValid = false;
	info.deterministic = false;
	return next.study(info);
	}
	}

	static final class Conditional extends Node {
	Node cond, yes, not;
	Conditional(Node cond, Node yes, Node not) {
	this.cond = cond;
	this.yes = yes;
	this.not = not;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	if (cond.match(matcher, i, seq)) {
	return yes.match(matcher, i, seq);
	} else {
	return not.match(matcher, i, seq);
	}
	}
	boolean study(TreeInfo info) {
	int minL = info.minLength;
	int maxL = info.maxLength;
	boolean maxV = info.maxValid;
	info.reset();
	yes.study(info);

	int minL2 = info.minLength;
	int maxL2 = info.maxLength;
	boolean maxV2 = info.maxValid;
	info.reset();
	not.study(info);

	info.minLength = minL + Math.min(minL2, info.minLength);
	info.maxLength = maxL + Math.max(maxL2, info.maxLength);
	info.maxValid = (maxV & maxV2 & info.maxValid);
	info.deterministic = false;
	return next.study(info);
	}
	}

	/**
	* Zero width positive lookahead.
	*/
	static final class Pos extends Node {
	Node cond;
	Pos(Node cond) {
	this.cond = cond;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int savedTo = matcher.to;
	boolean conditionMatched = false;

	// Relax transparent region boundaries for lookahead
	if (matcher.transparentBounds)
	matcher.to = matcher.getTextLength();
	try {
	conditionMatched = cond.match(matcher, i, seq);
	} finally {
	// Reinstate region boundaries
	matcher.to = savedTo;
	}
	return conditionMatched && next.match(matcher, i, seq);
	}
	}

	/**
	* Zero width negative lookahead.
	*/
	static final class Neg extends Node {
	Node cond;
	Neg(Node cond) {
	this.cond = cond;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int savedTo = matcher.to;
	boolean conditionMatched = false;

	// Relax transparent region boundaries for lookahead
	if (matcher.transparentBounds)
	matcher.to = matcher.getTextLength();
	try {
	if (i < matcher.to) {
	conditionMatched = !cond.match(matcher, i, seq);
	} else {
	// If a negative lookahead succeeds then more input
	// could cause it to fail!
	matcher.requireEnd = true;
	conditionMatched = !cond.match(matcher, i, seq);
	}
	} finally {
	// Reinstate region boundaries
	matcher.to = savedTo;
	}
	return conditionMatched && next.match(matcher, i, seq);
	}
	}

	/**
	* For use with lookbehinds; matches the position where the lookbehind
	* was encountered.
	*/
	static Node lookbehindEnd = new Node() {
	boolean match(Matcher matcher, int i, CharSequence seq) {
	return i == matcher.lookbehindTo;
	}
	};

	/**
	* Zero width positive lookbehind.
	*/
	static class Behind extends Node {
	Node cond;
	int rmax, rmin;
	Behind(Node cond, int rmax, int rmin) {
	this.cond = cond;
	this.rmax = rmax;
	this.rmin = rmin;
	}

	boolean match(Matcher matcher, int i, CharSequence seq) {
	int savedFrom = matcher.from;
	boolean conditionMatched = false;
	int startIndex = (!matcher.transparentBounds) ?
	matcher.from : 0;
	int from = Math.max(i - rmax, startIndex);
	// Set end boundary
	int savedLBT = matcher.lookbehindTo;
	matcher.lookbehindTo = i;
	// Relax transparent region boundaries for lookbehind
	if (matcher.transparentBounds)
	matcher.from = 0;
	for (int j = i - rmin; !conditionMatched && j >= from; j--) {
	conditionMatched = cond.match(matcher, j, seq);
	}
	matcher.from = savedFrom;
	matcher.lookbehindTo = savedLBT;
	return conditionMatched && next.match(matcher, i, seq);
	}
	}

	/**
	* Zero width positive lookbehind, including supplementary
	* characters or unpaired surrogates.
	*/
	static final class BehindS extends Behind {
	BehindS(Node cond, int rmax, int rmin) {
	super(cond, rmax, rmin);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int rmaxChars = countChars(seq, i, -rmax);
	int rminChars = countChars(seq, i, -rmin);
	int savedFrom = matcher.from;
	int startIndex = (!matcher.transparentBounds) ?
	matcher.from : 0;
	boolean conditionMatched = false;
	int from = Math.max(i - rmaxChars, startIndex);
	// Set end boundary
	int savedLBT = matcher.lookbehindTo;
	matcher.lookbehindTo = i;
	// Relax transparent region boundaries for lookbehind
	if (matcher.transparentBounds)
	matcher.from = 0;

	for (int j = i - rminChars;
	!conditionMatched && j >= from;
	j -= j>from ? countChars(seq, j, -1) : 1) {
	conditionMatched = cond.match(matcher, j, seq);
	}
	matcher.from = savedFrom;
	matcher.lookbehindTo = savedLBT;
	return conditionMatched && next.match(matcher, i, seq);
	}
	}

	/**
	* Zero width negative lookbehind.
	*/
	static class NotBehind extends Node {
	Node cond;
	int rmax, rmin;
	NotBehind(Node cond, int rmax, int rmin) {
	this.cond = cond;
	this.rmax = rmax;
	this.rmin = rmin;
	}

	boolean match(Matcher matcher, int i, CharSequence seq) {
	int savedLBT = matcher.lookbehindTo;
	int savedFrom = matcher.from;
	boolean conditionMatched = false;
	int startIndex = (!matcher.transparentBounds) ?
	matcher.from : 0;
	int from = Math.max(i - rmax, startIndex);
	matcher.lookbehindTo = i;
	// Relax transparent region boundaries for lookbehind
	if (matcher.transparentBounds)
	matcher.from = 0;
	for (int j = i - rmin; !conditionMatched && j >= from; j--) {
	conditionMatched = cond.match(matcher, j, seq);
	}
	// Reinstate region boundaries
	matcher.from = savedFrom;
	matcher.lookbehindTo = savedLBT;
	return !conditionMatched && next.match(matcher, i, seq);
	}
	}

	/**
	* Zero width negative lookbehind, including supplementary
	* characters or unpaired surrogates.
	*/
	static final class NotBehindS extends NotBehind {
	NotBehindS(Node cond, int rmax, int rmin) {
	super(cond, rmax, rmin);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int rmaxChars = countChars(seq, i, -rmax);
	int rminChars = countChars(seq, i, -rmin);
	int savedFrom = matcher.from;
	int savedLBT = matcher.lookbehindTo;
	boolean conditionMatched = false;
	int startIndex = (!matcher.transparentBounds) ?
	matcher.from : 0;
	int from = Math.max(i - rmaxChars, startIndex);
	matcher.lookbehindTo = i;
	// Relax transparent region boundaries for lookbehind
	if (matcher.transparentBounds)
	matcher.from = 0;
	for (int j = i - rminChars;
	!conditionMatched && j >= from;
	j -= j>from ? countChars(seq, j, -1) : 1) {
	conditionMatched = cond.match(matcher, j, seq);
	}
	//Reinstate region boundaries
	matcher.from = savedFrom;
	matcher.lookbehindTo = savedLBT;
	return !conditionMatched && next.match(matcher, i, seq);
	}
	}

	/**
	* Handles word boundaries. Includes a field to allow this one class to
	* deal with the different types of word boundaries we can match. The word
	* characters include underscores, letters, and digits. Non spacing marks
	* can are also part of a word if they have a base character, otherwise
	* they are ignored for purposes of finding word boundaries.
	*/
	static final class Bound extends Node {
	static int LEFT = 0x1;
	static int RIGHT= 0x2;
	static int BOTH = 0x3;
	static int NONE = 0x4;
	int type;
	boolean useUWORD;
	Bound(int n, boolean useUWORD) {
	type = n;
	this.useUWORD = useUWORD;
	}

	boolean isWord(int ch) {
	return useUWORD ? CharPredicates.WORD().is(ch)
	: (ch == '_' \|\| Character.isLetterOrDigit(ch));
	}

	int check(Matcher matcher, int i, CharSequence seq) {
	int ch;
	boolean left = false;
	int startIndex = matcher.from;
	int endIndex = matcher.to;
	if (matcher.transparentBounds) {
	startIndex = 0;
	endIndex = matcher.getTextLength();
	}
	if (i > startIndex) {
	ch = Character.codePointBefore(seq, i);
	left = (isWord(ch) \|\|
	((Character.getType(ch) == Character.NON_SPACING_MARK)
	&& hasBaseCharacter(matcher, i-1, seq)));
	}
	boolean right = false;
	if (i < endIndex) {
	ch = Character.codePointAt(seq, i);
	right = (isWord(ch) \|\|
	((Character.getType(ch) == Character.NON_SPACING_MARK)
	&& hasBaseCharacter(matcher, i, seq)));
	} else {
	// Tried to access char past the end
	matcher.hitEnd = true;
	// The addition of another char could wreck a boundary
	matcher.requireEnd = true;
	}
	return ((left ^ right) ? (right ? LEFT : RIGHT) : NONE);
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	return (check(matcher, i, seq) & type) > 0
	&& next.match(matcher, i, seq);
	}
	}

	/**
	* Non spacing marks only count as word characters in bounds calculations
	* if they have a base character.
	*/
	private static boolean hasBaseCharacter(Matcher matcher, int i,
	CharSequence seq)
	{
	int start = (!matcher.transparentBounds) ?
	matcher.from : 0;
	for (int x=i; x >= start; x--) {
	int ch = Character.codePointAt(seq, x);
	if (Character.isLetterOrDigit(ch))
	return true;
	if (Character.getType(ch) == Character.NON_SPACING_MARK)
	continue;
	return false;
	}
	return false;
	}

	/**
	* Attempts to match a slice in the input using the Boyer-Moore string
	* matching algorithm. The algorithm is based on the idea that the
	* pattern can be shifted farther ahead in the search text if it is
	* matched right to left.
	* <p>
	* The pattern is compared to the input one character at a time, from
	* the rightmost character in the pattern to the left. If the characters
	* all match the pattern has been found. If a character does not match,
	* the pattern is shifted right a distance that is the maximum of two
	* functions, the bad character shift and the good suffix shift. This
	* shift moves the attempted match position through the input more
	* quickly than a naive one position at a time check.
	* <p>
	* The bad character shift is based on the character from the text that
	* did not match. If the character does not appear in the pattern, the
	* pattern can be shifted completely beyond the bad character. If the
	* character does occur in the pattern, the pattern can be shifted to
	* line the pattern up with the next occurrence of that character.
	* <p>
	* The good suffix shift is based on the idea that some subset on the right
	* side of the pattern has matched. When a bad character is found, the
	* pattern can be shifted right by the pattern length if the subset does
	* not occur again in pattern, or by the amount of distance to the
	* next occurrence of the subset in the pattern.
	*
	* Boyer-Moore search methods adapted from code by Amy Yu.
	*/
	static class BnM extends Node {
	int[] buffer;
	int[] lastOcc;
	int[] optoSft;

	/**
	* Pre calculates arrays needed to generate the bad character
	* shift and the good suffix shift. Only the last seven bits
	* are used to see if chars match; This keeps the tables small
	* and covers the heavily used ASCII range, but occasionally
	* results in an aliased match for the bad character shift.
	*/
	static Node optimize(Node node) {
	if (!(node instanceof Slice)) {
	return node;
	}

	int[] src = ((Slice) node).buffer;
	int patternLength = src.length;
	// The BM algorithm requires a bit of overhead;
	// If the pattern is short don't use it, since
	// a shift larger than the pattern length cannot
	// be used anyway.
	if (patternLength < 4) {
	return node;
	}
	int i, j, k;
	int[] lastOcc = new int[128];
	int[] optoSft = new int[patternLength];
	// Precalculate part of the bad character shift
	// It is a table for where in the pattern each
	// lower 7-bit value occurs
	for (i = 0; i < patternLength; i++) {
	lastOcc[src[i]&0x7F] = i + 1;
	}
	// Precalculate the good suffix shift
	// i is the shift amount being considered
	NEXT: for (i = patternLength; i > 0; i--) {
	// j is the beginning index of suffix being considered
	for (j = patternLength - 1; j >= i; j--) {
	// Testing for good suffix
	if (src[j] == src[j-i]) {
	// src[j..len] is a good suffix
	optoSft[j-1] = i;
	} else {
	// No match. The array has already been
	// filled up with correct values before.
	continue NEXT;
	}
	}
	// This fills up the remaining of optoSft
	// any suffix can not have larger shift amount
	// then its sub-suffix. Why???
	while (j > 0) {
	optoSft[--j] = i;
	}
	}
	// Set the guard value because of unicode compression
	optoSft[patternLength-1] = 1;
	if (node instanceof SliceS)
	return new BnMS(src, lastOcc, optoSft, node.next);
	return new BnM(src, lastOcc, optoSft, node.next);
	}
	BnM(int[] src, int[] lastOcc, int[] optoSft, Node next) {
	this.buffer = src;
	this.lastOcc = lastOcc;
	this.optoSft = optoSft;
	this.next = next;
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int[] src = buffer;
	int patternLength = src.length;
	int last = matcher.to - patternLength;

	// Loop over all possible match positions in text
	NEXT: while (i <= last) {
	// Loop over pattern from right to left
	for (int j = patternLength - 1; j >= 0; j--) {
	int ch = seq.charAt(i+j);
	if (ch != src[j]) {
	// Shift search to the right by the maximum of the
	// bad character shift and the good suffix shift
	i += Math.max(j + 1 - lastOcc[ch&0x7F], optoSft[j]);
	continue NEXT;
	}
	}
	// Entire pattern matched starting at i
	matcher.first = i;
	boolean ret = next.match(matcher, i + patternLength, seq);
	if (ret) {
	matcher.first = i;
	matcher.groups[0] = matcher.first;
	matcher.groups[1] = matcher.last;
	return true;
	}
	i++;
	}
	// BnM is only used as the leading node in the unanchored case,
	// and it replaced its Start() which always searches to the end
	// if it doesn't find what it's looking for, so hitEnd is true.
	matcher.hitEnd = true;
	return false;
	}
	boolean study(TreeInfo info) {
	info.minLength += buffer.length;
	info.maxValid = false;
	return next.study(info);
	}
	}

	/**
	* Supplementary support version of BnM(). Unpaired surrogates are
	* also handled by this class.
	*/
	static final class BnMS extends BnM {
	int lengthInChars;

	BnMS(int[] src, int[] lastOcc, int[] optoSft, Node next) {
	super(src, lastOcc, optoSft, next);
	for (int cp : buffer) {
	lengthInChars += Character.charCount(cp);
	}
	}
	boolean match(Matcher matcher, int i, CharSequence seq) {
	int[] src = buffer;
	int patternLength = src.length;
	int last = matcher.to - lengthInChars;

	// Loop over all possible match positions in text
	NEXT: while (i <= last) {
	// Loop over pattern from right to left
	int ch;
	for (int j = countChars(seq, i, patternLength), x = patternLength - 1;
	j > 0; j -= Character.charCount(ch), x--) {
	ch = Character.codePointBefore(seq, i+j);
	if (ch != src[x]) {
	// Shift search to the right by the maximum of the
	// bad character shift and the good suffix shift
	int n = Math.max(x + 1 - lastOcc[ch&0x7F], optoSft[x]);
	i += countChars(seq, i, n);
	continue NEXT;
	}
	}
	// Entire pattern matched starting at i
	matcher.first = i;
	boolean ret = next.match(matcher, i + lengthInChars, seq);
	if (ret) {
	matcher.first = i;
	matcher.groups[0] = matcher.first;
	matcher.groups[1] = matcher.last;
	return true;
	}
	i += countChars(seq, i, 1);
	}
	matcher.hitEnd = true;
	return false;
	}
	}

	@FunctionalInterface
	static interface CharPredicate {
	boolean is(int ch);

	default CharPredicate and(CharPredicate p) {
	return ch -> is(ch) && p.is(ch);
	}
	default CharPredicate union(CharPredicate p) {
	return ch -> is(ch) \|\| p.is(ch);
	}
	default CharPredicate union(CharPredicate p1,
	CharPredicate p2 ) {
	return ch -> is(ch) \|\| p1.is(ch) \|\| p2.is(ch);
	}
	default CharPredicate negate() {
	return ch -> !is(ch);
	}
	}

	static interface BmpCharPredicate extends CharPredicate {

	default CharPredicate and(CharPredicate p) {
	if(p instanceof BmpCharPredicate)
	return (BmpCharPredicate)(ch -> is(ch) && p.is(ch));
	return ch -> is(ch) && p.is(ch);
	}
	default CharPredicate union(CharPredicate p) {
	if (p instanceof BmpCharPredicate)
	return (BmpCharPredicate)(ch -> is(ch) \|\| p.is(ch));
	return ch -> is(ch) \|\| p.is(ch);
	}
	static CharPredicate union(CharPredicate... predicates) {
	CharPredicate cp = ch -> {
	for (CharPredicate p : predicates) {
	if (!p.is(ch))
	return false;
	}
	return true;
	};
	for (CharPredicate p : predicates) {
	if (! (p instanceof BmpCharPredicate))
	return cp;
	}
	return (BmpCharPredicate)cp;
	}
	}

	/**
	* matches a Perl vertical whitespace
	*/
	static BmpCharPredicate VertWS() {
	return cp -> (cp >= 0x0A && cp <= 0x0D) \|\|
	cp == 0x85 \|\| cp == 0x2028 \|\| cp == 0x2029;
	}

	/**
	* matches a Perl horizontal whitespace
	*/
	static BmpCharPredicate HorizWS() {
	return cp ->
	cp == 0x09 \|\| cp == 0x20 \|\| cp == 0xa0 \|\| cp == 0x1680 \|\|
	cp == 0x180e \|\| cp >= 0x2000 && cp <= 0x200a \|\| cp == 0x202f \|\|
	cp == 0x205f \|\| cp == 0x3000;
	}

	/**
	* for the Unicode category ALL and the dot metacharacter when
	* in dotall mode.
	*/
	static CharPredicate ALL() {
	return ch -> true;
	}

	/**
	* for the dot metacharacter when dotall is not enabled.
	*/
	static CharPredicate DOT() {
	return ch ->
	(ch != '\n' && ch != '\r'
	&& (ch\|1) != '\u2029'
	&& ch != '\u0085');
	}

	/**
	* the dot metacharacter when dotall is not enabled but UNIX_LINES is enabled.
	*/
	static CharPredicate UNIXDOT() {
	return ch -> ch != '\n';
	}

	/**
	* Indicate that matches a Supplementary Unicode character
	*/
	static CharPredicate SingleS(int c) {
	return ch -> ch == c;
	}

	/**
	* A bmp/optimized predicate of single
	*/
	static BmpCharPredicate Single(int c) {
	return ch -> ch == c;
	}

	/**
	* Case insensitive matches a given BMP character
	*/
	static BmpCharPredicate SingleI(int lower, int upper) {
	return ch -> ch == lower \|\| ch == upper;
	}

	/**
	* Unicode case insensitive matches a given Unicode character
	*/
	static CharPredicate SingleU(int lower) {
	return ch -> lower == ch \|\|
	lower == Character.toLowerCase(Character.toUpperCase(ch));
	}

	private static boolean inRange(int lower, int ch, int upper) {
	return lower <= ch && ch <= upper;
	}

	/**
	* Charactrs within a explicit value range
	*/
	static CharPredicate Range(int lower, int upper) {
	if (upper < Character.MIN_HIGH_SURROGATE \|\|
	lower > Character.MAX_HIGH_SURROGATE &&
	upper < Character.MIN_SUPPLEMENTARY_CODE_POINT)
	return (BmpCharPredicate)(ch -> inRange(lower, ch, upper));
	return ch -> inRange(lower, ch, upper);
	}

	/**
	* Charactrs within a explicit value range in a case insensitive manner.
	*/
	static CharPredicate CIRange(int lower, int upper) {
	return ch -> inRange(lower, ch, upper) \|\|
	ASCII.isAscii(ch) &&
	(inRange(lower, ASCII.toUpper(ch), upper) \|\|
	inRange(lower, ASCII.toLower(ch), upper));
	}

	static CharPredicate CIRangeU(int lower, int upper) {
	return ch -> {
	if (inRange(lower, ch, upper))
	return true;
	int up = Character.toUpperCase(ch);
	return inRange(lower, up, upper) \|\|
	inRange(lower, Character.toLowerCase(up), upper);
	};
	}

	/**
	* This must be the very first initializer.
	*/
	static final Node accept = new Node();

	static final Node lastAccept = new LastNode();

	/**
	* Creates a predicate that tests if this pattern is found in a given input
	* string.
	*
	* @apiNote
	* This method creates a predicate that behaves as if it creates a matcher
	* from the input sequence and then calls {@code find}, for example a
	* predicate of the form:
	* <pre>{@code
	* s -> matcher(s).find();
	* }</pre>
	*
	* @return The predicate which can be used for finding a match on a
	* subsequence of a string
	* @since 1.8
	* @see Matcher#find
	*/
	public Predicate<String> asPredicate() {
	return s -> matcher(s).find();
	}

	/**
	* Creates a predicate that tests if this pattern matches a given input string.
	*
	* @apiNote
	* This method creates a predicate that behaves as if it creates a matcher
	* from the input sequence and then calls {@code matches}, for example a
	* predicate of the form:
	* <pre>{@code
	* s -> matcher(s).matches();
	* }</pre>
	*
	* @return The predicate which can be used for matching an input string
	* against this pattern.
	* @since 11
	* @see Matcher#matches
	*/
	public Predicate<String> asMatchPredicate() {
	return s -> matcher(s).matches();
	}

	/**
	* Creates a stream from the given input sequence around matches of this
	* pattern.
	*
	* <p> The stream returned by this method contains each substring of the
	* input sequence that is terminated by another subsequence that matches
	* this pattern or is terminated by the end of the input sequence. The
	* substrings in the stream are in the order in which they occur in the
	* input. Trailing empty strings will be discarded and not encountered in
	* the stream.
	*
	* <p> If this pattern does not match any subsequence of the input then
	* the resulting stream has just one element, namely the input sequence in
	* string form.
	*
	* <p> When there is a positive-width match at the beginning of the input
	* sequence then an empty leading substring is included at the beginning
	* of the stream. A zero-width match at the beginning however never produces
	* such empty leading substring.
	*
	* <p> If the input sequence is mutable, it must remain constant during the
	* execution of the terminal stream operation. Otherwise, the result of the
	* terminal stream operation is undefined.
	*
	* @param input
	* The character sequence to be split
	*
	* @return The stream of strings computed by splitting the input
	* around matches of this pattern
	* @see #split(CharSequence)
	* @since 1.8
	*/
	public Stream<String> splitAsStream(final CharSequence input) {
	class MatcherIterator implements Iterator<String> {
	private Matcher matcher;
	// The start position of the next sub-sequence of input
	// when current == input.length there are no more elements
	private int current;
	// null if the next element, if any, needs to obtained
	private String nextElement;
	// > 0 if there are N next empty elements
	private int emptyElementCount;

	public String next() {
	if (!hasNext())
	throw new NoSuchElementException();

	if (emptyElementCount == 0) {
	String n = nextElement;
	nextElement = null;
	return n;
	} else {
	emptyElementCount--;
	return "";
	}
	}

	public boolean hasNext() {
	if (matcher == null) {
	matcher = matcher(input);
	// If the input is an empty string then the result can only be a
	// stream of the input. Induce that by setting the empty
	// element count to 1
	emptyElementCount = input.length() == 0 ? 1 : 0;
	}
	if (nextElement != null \|\| emptyElementCount > 0)
	return true;

	if (current == input.length())
	return false;

	// Consume the next matching element
	// Count sequence of matching empty elements
	while (matcher.find()) {
	nextElement = input.subSequence(current, matcher.start()).toString();
	current = matcher.end();
	if (!nextElement.isEmpty()) {
	return true;
	} else if (current > 0) { // no empty leading substring for zero-width
	// match at the beginning of the input
	emptyElementCount++;
	}
	}

	// Consume last matching element
	nextElement = input.subSequence(current, input.length()).toString();
	current = input.length();
	if (!nextElement.isEmpty()) {
	return true;
	} else {
	// Ignore a terminal sequence of matching empty elements
	emptyElementCount = 0;
	nextElement = null;
	return false;
	}
	}
	}
	return StreamSupport.stream(Spliterators.spliteratorUnknownSize(
	new MatcherIterator(), Spliterator.ORDERED \| Spliterator.NONNULL), false);
	}
	}

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