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Java example source code file (NativeRegExp.java)

This example Java source code file (NativeRegExp.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

function, getter, global, nativeregexp, object, override, propertymap, regexpmatcher, regexpresult, scriptfunction, specializedconstructor, string, stringbuilder, undefined, util

The NativeRegExp.java Java example source code

/*
 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package jdk.nashorn.internal.objects;

import static jdk.nashorn.internal.runtime.ECMAErrors.typeError;
import static jdk.nashorn.internal.runtime.ScriptRuntime.UNDEFINED;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import jdk.nashorn.internal.objects.annotations.Attribute;
import jdk.nashorn.internal.objects.annotations.Constructor;
import jdk.nashorn.internal.objects.annotations.Function;
import jdk.nashorn.internal.objects.annotations.Getter;
import jdk.nashorn.internal.objects.annotations.Property;
import jdk.nashorn.internal.objects.annotations.ScriptClass;
import jdk.nashorn.internal.objects.annotations.SpecializedConstructor;
import jdk.nashorn.internal.objects.annotations.Where;
import jdk.nashorn.internal.runtime.BitVector;
import jdk.nashorn.internal.runtime.JSType;
import jdk.nashorn.internal.runtime.ParserException;
import jdk.nashorn.internal.runtime.PropertyMap;
import jdk.nashorn.internal.runtime.regexp.RegExp;
import jdk.nashorn.internal.runtime.regexp.RegExpFactory;
import jdk.nashorn.internal.runtime.regexp.RegExpResult;
import jdk.nashorn.internal.runtime.regexp.RegExpMatcher;
import jdk.nashorn.internal.runtime.ScriptFunction;
import jdk.nashorn.internal.runtime.ScriptObject;
import jdk.nashorn.internal.runtime.ScriptRuntime;

/**
 * ECMA 15.10 RegExp Objects.
 */
@ScriptClass("RegExp")
public final class NativeRegExp extends ScriptObject {
    /** ECMA 15.10.7.5 lastIndex property */
    @Property(attributes = Attribute.NOT_ENUMERABLE | Attribute.NOT_CONFIGURABLE)
    public Object lastIndex;

    /** Compiled regexp */
    private RegExp regexp;

    // Reference to global object needed to support static RegExp properties
    private final Global globalObject;

    // initialized by nasgen
    private static PropertyMap $nasgenmap$;

    static PropertyMap getInitialMap() {
        return $nasgenmap$;
    }

    private NativeRegExp(final Global global) {
        super(global.getRegExpPrototype(), global.getRegExpMap());
        this.globalObject = global;
    }

    NativeRegExp(final String input, final String flagString, final Global global) {
        this(global);
        try {
            this.regexp = RegExpFactory.create(input, flagString);
        } catch (final ParserException e) {
            // translate it as SyntaxError object and throw it
            e.throwAsEcmaException();
            throw new AssertionError(); //guard against null warnings below
        }

        this.setLastIndex(0);
    }

    NativeRegExp(final String input, final String flagString) {
        this(input, flagString, Global.instance());
    }

    NativeRegExp(final String string, final Global global) {
        this(string, "", global);
    }

    NativeRegExp(final String string) {
        this(string, Global.instance());
    }

    NativeRegExp(final NativeRegExp regExp) {
        this(Global.instance());
        this.lastIndex  = regExp.getLastIndexObject();
        this.regexp      = regExp.getRegExp();
    }

    @Override
    public String getClassName() {
        return "RegExp";
    }

    /**
     * ECMA 15.10.4
     *
     * Constructor
     *
     * @param isNew is the new operator used for instantiating this regexp
     * @param self  self reference
     * @param args  arguments (optional: pattern and flags)
     * @return new NativeRegExp
     */
    @Constructor(arity = 2)
    public static Object constructor(final boolean isNew, final Object self, final Object... args) {
        if (args.length > 1) {
            return newRegExp(args[0], args[1]);
        } else if (args.length > 0) {
            return newRegExp(args[0], UNDEFINED);
        }

        return newRegExp(UNDEFINED, UNDEFINED);
    }

    /**
     * ECMA 15.10.4
     *
     * Constructor - specialized version, no args, empty regexp
     *
     * @param isNew is the new operator used for instantiating this regexp
     * @param self  self reference
     * @return new NativeRegExp
     */
    @SpecializedConstructor
    public static Object constructor(final boolean isNew, final Object self) {
        return new NativeRegExp("", "");
    }

    /**
     * ECMA 15.10.4
     *
     * Constructor - specialized version, pattern, no flags
     *
     * @param isNew is the new operator used for instantiating this regexp
     * @param self  self reference
     * @param pattern pattern
     * @return new NativeRegExp
     */
    @SpecializedConstructor
    public static Object constructor(final boolean isNew, final Object self, final Object pattern) {
        return newRegExp(pattern, UNDEFINED);
    }

    /**
     * ECMA 15.10.4
     *
     * Constructor - specialized version, pattern and flags
     *
     * @param isNew is the new operator used for instantiating this regexp
     * @param self  self reference
     * @param pattern pattern
     * @param flags  flags
     * @return new NativeRegExp
     */
    @SpecializedConstructor
    public static Object constructor(final boolean isNew, final Object self, final Object pattern, final Object flags) {
        return newRegExp(pattern, flags);
    }

    /**
     * External constructor used in generated code, which explains the public access
     *
     * @param regexp regexp
     * @param flags  flags
     * @return new NativeRegExp
     */
    public static NativeRegExp newRegExp(final Object regexp, final Object flags) {
        String  patternString = "";
        String  flagString    = "";

        if (regexp != UNDEFINED) {
            if (regexp instanceof NativeRegExp) {
                if (flags != UNDEFINED) {
                    throw typeError("regex.cant.supply.flags");
                }
                return (NativeRegExp)regexp; // 15.10.3.1 - undefined flags and regexp as
            }
            patternString = JSType.toString(regexp);
        }

        if (flags != UNDEFINED) {
            flagString = JSType.toString(flags);
        }

        return new NativeRegExp(patternString, flagString);
    }

    /**
     * Build a regexp that matches {@code string} as-is. All meta-characters will be escaped.
     *
     * @param string pattern string
     * @return flat regexp
     */
    static NativeRegExp flatRegExp(String string) {
        // escape special characters
        StringBuilder sb = null;
        final int length = string.length();

        for (int i = 0; i < length; i++) {
            final char c = string.charAt(i);
            switch (c) {
                case '^':
                case '$':
                case '\\':
                case '.':
                case '*':
                case '+':
                case '?':
                case '(':
                case ')':
                case '[':
                case '{':
                case '|':
                    if (sb == null) {
                        sb = new StringBuilder(length * 2);
                        sb.append(string, 0, i);
                    }
                    sb.append('\\');
                    sb.append(c);
                    break;
                default:
                    if (sb != null) {
                        sb.append(c);
                    }
                    break;
            }
        }
        return new NativeRegExp(sb == null ? string : sb.toString(), "");
    }

    private String getFlagString() {
        final StringBuilder sb = new StringBuilder(3);

        if (regexp.isGlobal()) {
            sb.append('g');
        }
        if (regexp.isIgnoreCase()) {
            sb.append('i');
        }
        if (regexp.isMultiline()) {
            sb.append('m');
        }

        return sb.toString();
    }

    @Override
    public String safeToString() {
        return "[RegExp " + toString() + "]";
    }

    @Override
    public String toString() {
        return "/" + regexp.getSource() + "/" + getFlagString();
    }

    /**
     * Nashorn extension: RegExp.prototype.compile - everybody implements this!
     *
     * @param self    self reference
     * @param pattern pattern
     * @param flags   flags
     * @return new NativeRegExp
     */
    @Function(attributes = Attribute.NOT_ENUMERABLE)
    public static Object compile(final Object self, final Object pattern, final Object flags) {
        final NativeRegExp regExp   = checkRegExp(self);
        final NativeRegExp compiled = newRegExp(pattern, flags);
        // copy over regexp to 'self'
        regExp.setRegExp(compiled.getRegExp());

        // Some implementations return undefined. Some return 'self'. Since return
        // value is most likely be ignored, we can play safe and return 'self'.
        return regExp;
    }

    /**
     * ECMA 15.10.6.2 RegExp.prototype.exec(string)
     *
     * @param self   self reference
     * @param string string to match against regexp
     * @return array containing the matches or {@code null} if no match
     */
    @Function(attributes = Attribute.NOT_ENUMERABLE)
    public static Object exec(final Object self, final Object string) {
        return checkRegExp(self).exec(JSType.toString(string));
    }

    /**
     * ECMA 15.10.6.3 RegExp.prototype.test(string)
     *
     * @param self   self reference
     * @param string string to test for matches against regexp
     * @return true if matches found, false otherwise
     */
    @Function(attributes = Attribute.NOT_ENUMERABLE)
    public static Object test(final Object self, final Object string) {
        return checkRegExp(self).test(JSType.toString(string));
    }

    /**
     * ECMA 15.10.6.4 RegExp.prototype.toString()
     *
     * @param self self reference
     * @return string version of regexp
     */
    @Function(attributes = Attribute.NOT_ENUMERABLE)
    public static Object toString(final Object self) {
        return checkRegExp(self).toString();
    }

    /**
     * ECMA 15.10.7.1 source
     *
     * @param self self reference
     * @return the input string for the regexp
     */
    @Getter(attributes = Attribute.NON_ENUMERABLE_CONSTANT)
    public static Object source(final Object self) {
        return checkRegExp(self).getRegExp().getSource();
    }

    /**
     * ECMA 15.10.7.2 global
     *
     * @param self self reference
     * @return true if this regexp is flagged global, false otherwise
     */
    @Getter(attributes = Attribute.NON_ENUMERABLE_CONSTANT)
    public static Object global(final Object self) {
        return checkRegExp(self).getRegExp().isGlobal();
    }

    /**
     * ECMA 15.10.7.3 ignoreCase
     *
     * @param self self reference
     * @return true if this regexp if flagged to ignore case, false otherwise
     */
    @Getter(attributes = Attribute.NON_ENUMERABLE_CONSTANT)
    public static Object ignoreCase(final Object self) {
        return checkRegExp(self).getRegExp().isIgnoreCase();
    }

    /**
     * ECMA 15.10.7.4 multiline
     *
     * @param self self reference
     * @return true if this regexp is flagged to be multiline, false otherwise
     */
    @Getter(attributes = Attribute.NON_ENUMERABLE_CONSTANT)
    public static Object multiline(final Object self) {
        return checkRegExp(self).getRegExp().isMultiline();
    }

    /**
     * Getter for non-standard RegExp.input property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "input")
    public static Object getLastInput(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getInput();
    }

    /**
     * Getter for non-standard RegExp.multiline property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "multiline")
    public static Object getLastMultiline(Object self) {
        return false; // doesn't ever seem to become true and isn't documented anyhwere
    }

    /**
     * Getter for non-standard RegExp.lastMatch property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "lastMatch")
    public static Object getLastMatch(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getGroup(0);
    }

    /**
     * Getter for non-standard RegExp.lastParen property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "lastParen")
    public static Object getLastParen(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getLastParen();
    }

    /**
     * Getter for non-standard RegExp.leftContext property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "leftContext")
    public static Object getLeftContext(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getInput().substring(0, match.getIndex());
    }

    /**
     * Getter for non-standard RegExp.rightContext property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "rightContext")
    public static Object getRightContext(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getInput().substring(match.getIndex() + match.length());
    }

    /**
     * Getter for non-standard RegExp.$1 property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "$1")
    public static Object getGroup1(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getGroup(1);
    }

    /**
     * Getter for non-standard RegExp.$2 property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "$2")
    public static Object getGroup2(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getGroup(2);
    }

    /**
     * Getter for non-standard RegExp.$3 property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "$3")
    public static Object getGroup3(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getGroup(3);
    }

    /**
     * Getter for non-standard RegExp.$4 property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "$4")
    public static Object getGroup4(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getGroup(4);
    }

    /**
     * Getter for non-standard RegExp.$5 property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "$5")
    public static Object getGroup5(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getGroup(5);
    }

    /**
     * Getter for non-standard RegExp.$6 property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "$6")
    public static Object getGroup6(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getGroup(6);
    }

    /**
     * Getter for non-standard RegExp.$7 property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "$7")
    public static Object getGroup7(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getGroup(7);
    }

    /**
     * Getter for non-standard RegExp.$8 property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "$8")
    public static Object getGroup8(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getGroup(8);
    }

    /**
     * Getter for non-standard RegExp.$9 property.
     * @param self self object
     * @return last regexp input
     */
    @Getter(where = Where.CONSTRUCTOR, attributes = Attribute.CONSTANT, name = "$9")
    public static Object getGroup9(Object self) {
        final RegExpResult match = Global.instance().getLastRegExpResult();
        return match == null ? "" : match.getGroup(9);
    }

    private RegExpResult execInner(final String string) {
        final boolean isGlobal = regexp.isGlobal();
        int start = getLastIndex();
        if (!isGlobal) {
            start = 0;
        }

        if (start < 0 || start > string.length()) {
            if (isGlobal) {
                setLastIndex(0);
            }
            return null;
        }

        final RegExpMatcher matcher = regexp.match(string);
        if (matcher == null || !matcher.search(start)) {
            if (isGlobal) {
                setLastIndex(0);
            }
            return null;
        }

        if (isGlobal) {
            setLastIndex(matcher.end());
        }

        final RegExpResult match = new RegExpResult(string, matcher.start(), groups(matcher));
        globalObject.setLastRegExpResult(match);
        return match;
    }

    // String.prototype.split method ignores the global flag and should not update lastIndex property.
    private RegExpResult execSplit(final String string, int start) {
        if (start < 0 || start > string.length()) {
            return null;
        }

        final RegExpMatcher matcher = regexp.match(string);
        if (matcher == null || !matcher.search(start)) {
            return null;
        }

        final RegExpResult match = new RegExpResult(string, matcher.start(), groups(matcher));
        globalObject.setLastRegExpResult(match);
        return match;
    }

    /**
     * Convert java.util.regex.Matcher groups to JavaScript groups.
     * That is, replace null and groups that didn't match with undefined.
     */
    private Object[] groups(final RegExpMatcher matcher) {
        final int groupCount = matcher.groupCount();
        final Object[] groups = new Object[groupCount + 1];
        final BitVector groupsInNegativeLookahead  = regexp.getGroupsInNegativeLookahead();

        for (int i = 0, lastGroupStart = matcher.start(); i <= groupCount; i++) {
            final int groupStart = matcher.start(i);
            if (lastGroupStart > groupStart
                    || (groupsInNegativeLookahead != null && groupsInNegativeLookahead.isSet(i))) {
                // (1) ECMA 15.10.2.5 NOTE 3: need to clear Atom's captures each time Atom is repeated.
                // (2) ECMA 15.10.2.8 NOTE 3: Backreferences to captures in (?!Disjunction) from elsewhere
                // in the pattern always return undefined because the negative lookahead must fail.
                groups[i] = UNDEFINED;
                continue;
            }
            final String group = matcher.group(i);
            groups[i] = group == null ? UNDEFINED : group;
            lastGroupStart = groupStart;
        }
        return groups;
    }

    /**
     * Executes a search for a match within a string based on a regular
     * expression. It returns an array of information or null if no match is
     * found.
     *
     * @param string String to match.
     * @return NativeArray of matches, string or null.
     */
    public Object exec(final String string) {
        final RegExpResult match = execInner(string);

        if (match == null) {
            return null;
        }

        return new NativeRegExpExecResult(match, globalObject);
    }

    /**
     * Executes a search for a match within a string based on a regular
     * expression.
     *
     * @param string String to match.
     * @return True if a match is found.
     */
    public Object test(final String string) {
        return execInner(string) != null;
    }

    /**
     * Searches and replaces the regular expression portion (match) with the
     * replaced text instead. For the "replacement text" parameter, you can use
     * the keywords $1 to $2 to replace the original text with values from
     * sub-patterns defined within the main pattern.
     *
     * @param string String to match.
     * @param replacement Replacement string.
     * @return String with substitutions.
     */
    Object replace(final String string, final String replacement, final ScriptFunction function) {
        final RegExpMatcher matcher = regexp.match(string);

        if (matcher == null) {
            return string;
        }

        if (!regexp.isGlobal()) {
            if (!matcher.search(0)) {
                return string;
            }

            final StringBuilder sb = new StringBuilder();
            sb.append(string, 0, matcher.start());

            if (function != null) {
                sb.append(callReplaceValue(function, matcher, string));
            } else {
                appendReplacement(matcher, string, replacement, sb);
            }
            sb.append(string, matcher.end(), string.length());
            return sb.toString();
        }

        setLastIndex(0);

        if (!matcher.search(0)) {
            return string;
        }

        int thisIndex = 0;
        int previousLastIndex = 0;
        final StringBuilder sb = new StringBuilder();

        do {
            sb.append(string, thisIndex, matcher.start());
            if (function != null) {
                sb.append(callReplaceValue(function, matcher, string));
            } else {
                appendReplacement(matcher, string, replacement, sb);
            }

            thisIndex = matcher.end();
            if (thisIndex == string.length() && matcher.start() == matcher.end()) {
                // Avoid getting empty match at end of string twice
                break;
            }

            // ECMA 15.5.4.10 String.prototype.match(regexp)
            if (thisIndex == previousLastIndex) {
                setLastIndex(thisIndex + 1);
                previousLastIndex = thisIndex + 1;
            } else {
                previousLastIndex = thisIndex;
            }
        } while (previousLastIndex <= string.length() && matcher.search(previousLastIndex));

        sb.append(string, thisIndex, string.length());

        return sb.toString();
    }

    private void appendReplacement(final RegExpMatcher matcher, final String text, final String replacement, final StringBuilder sb) {
        /*
         * Process substitution patterns:
         *
         * $$ -> $
         * $& -> the matched substring
         * $` -> the portion of string that preceeds matched substring
         * $' -> the portion of string that follows the matched substring
         * $n -> the nth capture, where n is [1-9] and $n is NOT followed by a decimal digit
         * $nn -> the nnth capture, where nn is a two digit decimal number [01-99].
         */

        int cursor = 0;
        Object[] groups = null;

        while (cursor < replacement.length()) {
            char nextChar = replacement.charAt(cursor);
            if (nextChar == '$') {
                // Skip past $
                cursor++;
                nextChar = replacement.charAt(cursor);
                final int firstDigit = nextChar - '0';

                if (firstDigit >= 0 && firstDigit <= 9 && firstDigit <= matcher.groupCount()) {
                    // $0 is not supported, but $01 is. implementation-defined: if n>m, ignore second digit.
                    int refNum = firstDigit;
                    cursor++;
                    if (cursor < replacement.length() && firstDigit < matcher.groupCount()) {
                        final int secondDigit = replacement.charAt(cursor) - '0';
                        if ((secondDigit >= 0) && (secondDigit <= 9)) {
                            final int newRefNum = (firstDigit * 10) + secondDigit;
                            if (newRefNum <= matcher.groupCount() && newRefNum > 0) {
                                // $nn ($01-$99)
                                refNum = newRefNum;
                                cursor++;
                            }
                        }
                    }
                    if (refNum > 0) {
                        if (groups == null) {
                            groups = groups(matcher);
                        }
                        // Append group if matched.
                        if (groups[refNum] != UNDEFINED) {
                            sb.append((String) groups[refNum]);
                        }
                    } else { // $0. ignore.
                        assert refNum == 0;
                        sb.append("$0");
                    }
                } else if (nextChar == '$') {
                    sb.append('$');
                    cursor++;
                } else if (nextChar == '&') {
                    sb.append(matcher.group());
                    cursor++;
                } else if (nextChar == '`') {
                    sb.append(text, 0, matcher.start());
                    cursor++;
                } else if (nextChar == '\'') {
                    sb.append(text, matcher.end(), text.length());
                    cursor++;
                } else {
                    // unknown substitution or $n with n>m. skip.
                    sb.append('$');
                }
            } else {
                sb.append(nextChar);
                cursor++;
            }
        }
    }

    private String callReplaceValue(final ScriptFunction function, final RegExpMatcher matcher, final String string) {
        final Object[] groups = groups(matcher);
        final Object[] args   = Arrays.copyOf(groups, groups.length + 2);

        args[groups.length]     = matcher.start();
        args[groups.length + 1] = string;

        final Object self = function.isStrict() ? UNDEFINED : Global.instance();

        return JSType.toString(ScriptRuntime.apply(function, self, args));
    }

    /**
     * Breaks up a string into an array of substrings based on a regular
     * expression or fixed string.
     *
     * @param string String to match.
     * @param limit  Split limit.
     * @return Array of substrings.
     */
    Object split(final String string, final long limit) {
        if (limit == 0L) {
            return new NativeArray();
        }

        final List<Object> matches = new ArrayList<>();

        RegExpResult match;
        final int inputLength = string.length();
        int splitLastLength = -1;
        int splitLastIndex = 0;
        int splitLastLastIndex = 0;

        while ((match = execSplit(string, splitLastIndex)) != null) {
            splitLastIndex = match.getIndex() + match.length();

            if (splitLastIndex > splitLastLastIndex) {
                matches.add(string.substring(splitLastLastIndex, match.getIndex()));
                final Object[] groups = match.getGroups();
                if (groups.length > 1 && match.getIndex() < inputLength) {
                    for (int index = 1; index < groups.length && matches.size() < limit; index++) {
                        matches.add(groups[index]);
                    }
                }

                splitLastLength = match.length();

                if (matches.size() >= limit) {
                    break;
                }
            }

            // bump the index to avoid infinite loop
            if (splitLastIndex == splitLastLastIndex) {
                splitLastIndex++;
            } else {
                splitLastLastIndex = splitLastIndex;
            }
        }

        if (matches.size() < limit) {
            // check special case if we need to append an empty string at the
            // end of the match
            // if the lastIndex was the entire string
            if (splitLastLastIndex == string.length()) {
                if (splitLastLength > 0 || execSplit("", 0) == null) {
                    matches.add("");
                }
            } else {
                matches.add(string.substring(splitLastLastIndex, inputLength));
            }
        }

        return new NativeArray(matches.toArray());
    }

    /**
     * Tests for a match in a string. It returns the index of the match, or -1
     * if not found.
     *
     * @param string String to match.
     * @return Index of match.
     */
    Object search(final String string) {
        final RegExpResult match = execInner(string);

        if (match == null) {
            return -1;
        }

        return match.getIndex();
    }

    /**
     * Fast lastIndex getter
     * @return last index property as int
     */
    public int getLastIndex() {
        return JSType.toInteger(lastIndex);
    }

    /**
     * Fast lastIndex getter
     * @return last index property as boxed integer
     */
    public Object getLastIndexObject() {
        return lastIndex;
    }

    /**
     * Fast lastIndex setter
     * @param lastIndex lastIndex
     */
    public void setLastIndex(final int lastIndex) {
        this.lastIndex = JSType.toObject(lastIndex);
    }

    private static NativeRegExp checkRegExp(final Object self) {
        Global.checkObjectCoercible(self);
        if (self instanceof NativeRegExp) {
            return (NativeRegExp)self;
        } else if (self != null && self == Global.instance().getRegExpPrototype()) {
            return Global.instance().DEFAULT_REGEXP;
        } else {
            throw typeError("not.a.regexp", ScriptRuntime.safeToString(self));
        }
    }

    boolean getGlobal() {
        return regexp.isGlobal();
    }

    private RegExp getRegExp() {
        return regexp;
    }

    private void setRegExp(final RegExp regexp) {
        this.regexp = regexp;
    }

}

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