var EOF = 0;
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// https://drafts.csswg.org/css-syntax-3/
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// § 4.2. Definitions
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// digit
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// A code point between U+0030 DIGIT ZERO (0) and U+0039 DIGIT NINE (9).
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function isDigit(code) {
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return code >= 0x0030 && code <= 0x0039;
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}
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// hex digit
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// A digit, or a code point between U+0041 LATIN CAPITAL LETTER A (A) and U+0046 LATIN CAPITAL LETTER F (F),
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// or a code point between U+0061 LATIN SMALL LETTER A (a) and U+0066 LATIN SMALL LETTER F (f).
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function isHexDigit(code) {
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return (
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isDigit(code) || // 0 .. 9
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(code >= 0x0041 && code <= 0x0046) || // A .. F
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(code >= 0x0061 && code <= 0x0066) // a .. f
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);
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}
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// uppercase letter
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// A code point between U+0041 LATIN CAPITAL LETTER A (A) and U+005A LATIN CAPITAL LETTER Z (Z).
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function isUppercaseLetter(code) {
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return code >= 0x0041 && code <= 0x005A;
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}
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// lowercase letter
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// A code point between U+0061 LATIN SMALL LETTER A (a) and U+007A LATIN SMALL LETTER Z (z).
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function isLowercaseLetter(code) {
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return code >= 0x0061 && code <= 0x007A;
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}
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// letter
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// An uppercase letter or a lowercase letter.
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function isLetter(code) {
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return isUppercaseLetter(code) || isLowercaseLetter(code);
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}
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// non-ASCII code point
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// A code point with a value equal to or greater than U+0080 <control>.
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function isNonAscii(code) {
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return code >= 0x0080;
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}
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// name-start code point
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// A letter, a non-ASCII code point, or U+005F LOW LINE (_).
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function isNameStart(code) {
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return isLetter(code) || isNonAscii(code) || code === 0x005F;
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}
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// name code point
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// A name-start code point, a digit, or U+002D HYPHEN-MINUS (-).
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function isName(code) {
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return isNameStart(code) || isDigit(code) || code === 0x002D;
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}
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// non-printable code point
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// A code point between U+0000 NULL and U+0008 BACKSPACE, or U+000B LINE TABULATION,
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// or a code point between U+000E SHIFT OUT and U+001F INFORMATION SEPARATOR ONE, or U+007F DELETE.
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function isNonPrintable(code) {
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return (
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(code >= 0x0000 && code <= 0x0008) ||
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(code === 0x000B) ||
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(code >= 0x000E && code <= 0x001F) ||
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(code === 0x007F)
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);
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}
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// newline
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// U+000A LINE FEED. Note that U+000D CARRIAGE RETURN and U+000C FORM FEED are not included in this definition,
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// as they are converted to U+000A LINE FEED during preprocessing.
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// TODO: we doesn't do a preprocessing, so check a code point for U+000D CARRIAGE RETURN and U+000C FORM FEED
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function isNewline(code) {
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return code === 0x000A || code === 0x000D || code === 0x000C;
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}
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// whitespace
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// A newline, U+0009 CHARACTER TABULATION, or U+0020 SPACE.
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function isWhiteSpace(code) {
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return isNewline(code) || code === 0x0020 || code === 0x0009;
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}
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// § 4.3.8. Check if two code points are a valid escape
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function isValidEscape(first, second) {
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// If the first code point is not U+005C REVERSE SOLIDUS (\), return false.
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if (first !== 0x005C) {
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return false;
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}
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// Otherwise, if the second code point is a newline or EOF, return false.
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if (isNewline(second) || second === EOF) {
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return false;
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}
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// Otherwise, return true.
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return true;
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}
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// § 4.3.9. Check if three code points would start an identifier
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function isIdentifierStart(first, second, third) {
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// Look at the first code point:
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// U+002D HYPHEN-MINUS
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if (first === 0x002D) {
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// If the second code point is a name-start code point or a U+002D HYPHEN-MINUS,
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// or the second and third code points are a valid escape, return true. Otherwise, return false.
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return (
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isNameStart(second) ||
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second === 0x002D ||
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isValidEscape(second, third)
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);
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}
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// name-start code point
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if (isNameStart(first)) {
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// Return true.
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return true;
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}
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// U+005C REVERSE SOLIDUS (\)
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if (first === 0x005C) {
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// If the first and second code points are a valid escape, return true. Otherwise, return false.
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return isValidEscape(first, second);
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}
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// anything else
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// Return false.
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return false;
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}
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// § 4.3.10. Check if three code points would start a number
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function isNumberStart(first, second, third) {
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// Look at the first code point:
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// U+002B PLUS SIGN (+)
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// U+002D HYPHEN-MINUS (-)
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if (first === 0x002B || first === 0x002D) {
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// If the second code point is a digit, return true.
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if (isDigit(second)) {
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return 2;
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}
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// Otherwise, if the second code point is a U+002E FULL STOP (.)
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// and the third code point is a digit, return true.
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// Otherwise, return false.
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return second === 0x002E && isDigit(third) ? 3 : 0;
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}
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// U+002E FULL STOP (.)
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if (first === 0x002E) {
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// If the second code point is a digit, return true. Otherwise, return false.
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return isDigit(second) ? 2 : 0;
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}
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// digit
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if (isDigit(first)) {
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// Return true.
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return 1;
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}
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// anything else
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// Return false.
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return 0;
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}
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//
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// Misc
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//
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// detect BOM (https://en.wikipedia.org/wiki/Byte_order_mark)
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function isBOM(code) {
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// UTF-16BE
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if (code === 0xFEFF) {
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return 1;
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}
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// UTF-16LE
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if (code === 0xFFFE) {
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return 1;
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}
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return 0;
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}
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// Fast code category
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//
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// https://drafts.csswg.org/css-syntax/#tokenizer-definitions
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// > non-ASCII code point
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// > A code point with a value equal to or greater than U+0080 <control>
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// > name-start code point
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// > A letter, a non-ASCII code point, or U+005F LOW LINE (_).
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// > name code point
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// > A name-start code point, a digit, or U+002D HYPHEN-MINUS (-)
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// That means only ASCII code points has a special meaning and we define a maps for 0..127 codes only
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var CATEGORY = new Array(0x80);
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charCodeCategory.Eof = 0x80;
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charCodeCategory.WhiteSpace = 0x82;
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charCodeCategory.Digit = 0x83;
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charCodeCategory.NameStart = 0x84;
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charCodeCategory.NonPrintable = 0x85;
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for (var i = 0; i < CATEGORY.length; i++) {
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switch (true) {
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case isWhiteSpace(i):
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CATEGORY[i] = charCodeCategory.WhiteSpace;
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break;
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case isDigit(i):
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CATEGORY[i] = charCodeCategory.Digit;
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break;
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case isNameStart(i):
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CATEGORY[i] = charCodeCategory.NameStart;
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break;
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case isNonPrintable(i):
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CATEGORY[i] = charCodeCategory.NonPrintable;
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break;
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default:
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CATEGORY[i] = i || charCodeCategory.Eof;
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}
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}
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function charCodeCategory(code) {
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return code < 0x80 ? CATEGORY[code] : charCodeCategory.NameStart;
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};
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module.exports = {
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isDigit: isDigit,
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isHexDigit: isHexDigit,
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isUppercaseLetter: isUppercaseLetter,
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isLowercaseLetter: isLowercaseLetter,
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isLetter: isLetter,
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isNonAscii: isNonAscii,
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isNameStart: isNameStart,
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isName: isName,
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isNonPrintable: isNonPrintable,
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isNewline: isNewline,
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isWhiteSpace: isWhiteSpace,
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isValidEscape: isValidEscape,
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isIdentifierStart: isIdentifierStart,
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isNumberStart: isNumberStart,
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isBOM: isBOM,
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charCodeCategory: charCodeCategory
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};
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