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java-team-github-botGoogle Java Core Libraries
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Google Java Core Libraries
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Optimize StringUtil.javaScriptEscape() by replacing boxed Set lookups with binary search and fast-path range checks.
RELNOTES=n/a PiperOrigin-RevId: 918765667
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‎android/guava-tests/benchmark/com/google/common/base/StringUtilJmhBenchmark.java‎

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package com.google.common.base;
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import static java.util.concurrent.TimeUnit.NANOSECONDS;
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import java.io.IOException;
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import java.util.HashSet;
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import java.util.Set;
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import org.openjdk.jmh.annotations.Benchmark;
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import org.openjdk.jmh.annotations.BenchmarkMode;
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import org.openjdk.jmh.annotations.Fork;
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import org.openjdk.jmh.annotations.Mode;
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import org.openjdk.jmh.annotations.OutputTimeUnit;
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import org.openjdk.jmh.annotations.Param;
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import org.openjdk.jmh.annotations.Scope;
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import org.openjdk.jmh.annotations.Setup;
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import org.openjdk.jmh.annotations.State;
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@BenchmarkMode(Mode.AverageTime)
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@OutputTimeUnit(NANOSECONDS)
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@State(Scope.Benchmark)
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@Fork(5)
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public class StringUtilJmhBenchmark {
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@Param({"100", "1000"})
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private int length;
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@Param({"ASCII", "CJK"})
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private String type;
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private String input;
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@Setup
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public void setUp() {
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StringBuilder sb = new StringBuilder(length);
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for (int i = 0; i < length; i++) {
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if ("ASCII".equals(type)) {
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sb.append((char) ('a' + (i % 26)));
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} else {
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sb.append((char) (0x4e00 + (i % 1000))); // Chinese ideographs
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}
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}
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input = sb.toString();
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}
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@Benchmark
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public String escapeUnicodeCurrent() {
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return StringUtil.javaScriptEscape(input);
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}
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@Benchmark
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public String escapeUnicodeOriginal() {
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return originalJavaScriptEscape(input, false);
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}
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@Benchmark
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public String escapeAsciiCurrent() {
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return StringUtil.javaScriptEscapeToAscii(input);
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}
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@Benchmark
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public String escapeAsciiOriginal() {
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return originalJavaScriptEscape(input, true);
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}
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private static String originalJavaScriptEscape(CharSequence s, boolean escapeToAscii) {
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StringBuilder sb = new StringBuilder(s.length() * 9 / 8);
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try {
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originalEscapeStringBody(s, escapeToAscii, StringUtil.JsEscapingMode.EMBEDDABLE_JS, sb);
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} catch (IOException ex) {
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throw new RuntimeException(ex);
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}
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return sb.toString();
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}
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private static void originalEscapeStringBody(
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CharSequence plainText,
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boolean escapeToAscii,
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StringUtil.JsEscapingMode jsEscapingMode,
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Appendable out)
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throws IOException {
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int pos = 0;
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int len = plainText.length();
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for (int codePoint, charCount, i = 0; i < len; i += charCount) {
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codePoint = Character.codePointAt(plainText, i);
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charCount = Character.charCount(codePoint);
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if (!originalShouldEscapeChar(codePoint, escapeToAscii, jsEscapingMode)) {
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continue;
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}
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out.append(plainText, pos, i);
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pos = i + charCount;
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switch (codePoint) {
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case '\b':
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out.append("\\b");
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break;
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case '\t':
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out.append("\\t");
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break;
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case '\n':
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out.append("\\n");
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break;
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case '\f':
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out.append("\\f");
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break;
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case '\r':
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out.append("\\r");
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break;
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case '\\':
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out.append("\\\\");
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break;
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case '"':
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case '\'':
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if (jsEscapingMode == StringUtil.JsEscapingMode.JSON && codePoint == '\'') {
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out.append((char) codePoint);
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break;
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} else if (jsEscapingMode != StringUtil.JsEscapingMode.EMBEDDABLE_JS) {
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out.append('\\').append((char) codePoint);
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break;
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}
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// fall through
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default:
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if (codePoint >= 0x100 || jsEscapingMode == StringUtil.JsEscapingMode.JSON) {
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appendUnicode(codePoint, out);
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} else {
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appendHex((char) codePoint, out);
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}
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break;
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}
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}
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out.append(plainText, pos, len);
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}
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private static boolean originalShouldEscapeChar(
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int codePoint, boolean escapeToAscii, StringUtil.JsEscapingMode jsEscapingMode) {
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if (escapeToAscii && (codePoint < 0x20 || codePoint > 0x7e)) {
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return true;
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}
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return ORIGINAL_JS_ESCAPE_CHARS.contains(codePoint);
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}
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private static final char[] hexChars = "0123456789abcdef".toCharArray();
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private static void appendHex(char ch, Appendable out) throws IOException {
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out.append("\\x").append(hexChars[(ch >>> 4) & 0xf]).append(hexChars[ch & 0xf]);
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}
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private static void appendUnicode(int codePoint, Appendable out) throws IOException {
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if (Character.isSupplementaryCodePoint(codePoint)) {
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char[] surrogates = Character.toChars(codePoint);
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appendUnicode(surrogates[0], out);
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appendUnicode(surrogates[1], out);
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return;
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}
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out.append("\\u")
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.append(hexChars[(codePoint >>> 12) & 0xf])
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.append(hexChars[(codePoint >>> 8) & 0xf])
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.append(hexChars[(codePoint >>> 4) & 0xf])
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.append(hexChars[codePoint & 0xf]);
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}
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private static final class BoxedCodePointSet {
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final boolean[] fastArray;
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final Set<Integer> elements;
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BoxedCodePointSet(Set<Integer> codePoints) {
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this.elements = codePoints;
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fastArray = new boolean[0x100];
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for (int i = 0; i < fastArray.length; i++) {
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fastArray[i] = elements.contains(i);
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}
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}
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boolean contains(int codePoint) {
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if (codePoint < fastArray.length) {
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return fastArray[codePoint];
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}
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return elements.contains(codePoint);
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}
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}
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private static final BoxedCodePointSet ORIGINAL_JS_ESCAPE_CHARS;
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static {
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Set<Integer> set = new HashSet<>();
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set.add(0xAD);
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for (int i = 0x600; i <= 0x603; i++) set.add(i);
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set.add(0x6DD);
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set.add(0x070F);
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for (int i = 0x17B4; i <= 0x17B5; i++) set.add(i);
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for (int i = 0x200B; i <= 0x200F; i++) set.add(i);
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for (int i = 0x202A; i <= 0x202E; i++) set.add(i);
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for (int i = 0x2028; i <= 0x2029; i++) set.add(i);
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for (int i = 0x2060; i <= 0x2064; i++) set.add(i);
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for (int i = 0x206A; i <= 0x206F; i++) set.add(i);
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set.add(0xFEFF);
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for (int i = 0xFFF9; i <= 0xFFFB; i++) set.add(i);
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for (int i = 0x1D173; i <= 0x1D17A; i++) set.add(i);
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set.add(0xE0001);
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for (int i = 0xE0020; i <= 0xE007F; i++) set.add(i);
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set.add(0x0000);
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set.add(0x000A);
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set.add(0x000D);
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set.add(0x0085);
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set.add((int) '\'');
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set.add((int) '\"');
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set.add((int) '&');
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set.add((int) '<');
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set.add((int) '>');
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set.add((int) '=');
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set.add((int) '\\');
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ORIGINAL_JS_ESCAPE_CHARS = new BoxedCodePointSet(set);
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}
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}

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