var isHexDigit = require('../tokenizer').isHexDigit;
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var cmpChar = require('../tokenizer').cmpChar;
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var TYPE = require('../tokenizer').TYPE;
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var IDENT = TYPE.Ident;
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var DELIM = TYPE.Delim;
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var NUMBER = TYPE.Number;
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var DIMENSION = TYPE.Dimension;
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var PLUSSIGN = 0x002B; // U+002B PLUS SIGN (+)
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var HYPHENMINUS = 0x002D; // U+002D HYPHEN-MINUS (-)
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var QUESTIONMARK = 0x003F; // U+003F QUESTION MARK (?)
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var U = 0x0075; // U+0075 LATIN SMALL LETTER U (u)
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function isDelim(token, code) {
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return token !== null && token.type === DELIM && token.value.charCodeAt(0) === code;
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}
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function startsWith(token, code) {
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return token.value.charCodeAt(0) === code;
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}
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function hexSequence(token, offset, allowDash) {
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for (var pos = offset, hexlen = 0; pos < token.value.length; pos++) {
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var code = token.value.charCodeAt(pos);
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if (code === HYPHENMINUS && allowDash && hexlen !== 0) {
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if (hexSequence(token, offset + hexlen + 1, false) > 0) {
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return 6; // dissallow following question marks
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}
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return 0; // dash at the ending of a hex sequence is not allowed
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}
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if (!isHexDigit(code)) {
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return 0; // not a hex digit
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}
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if (++hexlen > 6) {
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return 0; // too many hex digits
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};
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}
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return hexlen;
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}
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function withQuestionMarkSequence(consumed, length, getNextToken) {
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if (!consumed) {
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return 0; // nothing consumed
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}
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while (isDelim(getNextToken(length), QUESTIONMARK)) {
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if (++consumed > 6) {
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return 0; // too many question marks
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}
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length++;
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}
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return length;
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}
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// https://drafts.csswg.org/css-syntax/#urange
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// Informally, the <urange> production has three forms:
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// U+0001
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// Defines a range consisting of a single code point, in this case the code point "1".
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// U+0001-00ff
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// Defines a range of codepoints between the first and the second value, in this case
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// the range between "1" and "ff" (255 in decimal) inclusive.
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// U+00??
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// Defines a range of codepoints where the "?" characters range over all hex digits,
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// in this case defining the same as the value U+0000-00ff.
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// In each form, a maximum of 6 digits is allowed for each hexadecimal number (if you treat "?" as a hexadecimal digit).
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//
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// <urange> =
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// u '+' <ident-token> '?'* |
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// u <dimension-token> '?'* |
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// u <number-token> '?'* |
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// u <number-token> <dimension-token> |
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// u <number-token> <number-token> |
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// u '+' '?'+
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module.exports = function urange(token, getNextToken) {
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var length = 0;
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// should start with `u` or `U`
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if (token === null || token.type !== IDENT || !cmpChar(token.value, 0, U)) {
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return 0;
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}
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token = getNextToken(++length);
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if (token === null) {
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return 0;
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}
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// u '+' <ident-token> '?'*
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// u '+' '?'+
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if (isDelim(token, PLUSSIGN)) {
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token = getNextToken(++length);
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if (token === null) {
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return 0;
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}
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if (token.type === IDENT) {
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// u '+' <ident-token> '?'*
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return withQuestionMarkSequence(hexSequence(token, 0, true), ++length, getNextToken);
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}
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if (isDelim(token, QUESTIONMARK)) {
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// u '+' '?'+
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return withQuestionMarkSequence(1, ++length, getNextToken);
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}
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// Hex digit or question mark is expected
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return 0;
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}
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// u <number-token> '?'*
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// u <number-token> <dimension-token>
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// u <number-token> <number-token>
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if (token.type === NUMBER) {
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if (!startsWith(token, PLUSSIGN)) {
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return 0;
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}
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var consumedHexLength = hexSequence(token, 1, true);
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if (consumedHexLength === 0) {
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return 0;
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}
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token = getNextToken(++length);
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if (token === null) {
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// u <number-token> <eof>
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return length;
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}
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if (token.type === DIMENSION || token.type === NUMBER) {
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// u <number-token> <dimension-token>
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// u <number-token> <number-token>
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if (!startsWith(token, HYPHENMINUS) || !hexSequence(token, 1, false)) {
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return 0;
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}
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return length + 1;
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}
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// u <number-token> '?'*
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return withQuestionMarkSequence(consumedHexLength, length, getNextToken);
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}
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// u <dimension-token> '?'*
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if (token.type === DIMENSION) {
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if (!startsWith(token, PLUSSIGN)) {
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return 0;
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}
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return withQuestionMarkSequence(hexSequence(token, 1, true), ++length, getNextToken);
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}
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return 0;
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};
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