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