generic-urange.cjs•4.45 kB
'use strict';
const charCodeDefinitions = require('../tokenizer/char-code-definitions.cjs');
const types = require('../tokenizer/types.cjs');
const utils = require('../tokenizer/utils.cjs');
const PLUSSIGN = 0x002B; // U+002B PLUS SIGN (+)
const HYPHENMINUS = 0x002D; // U+002D HYPHEN-MINUS (-)
const QUESTIONMARK = 0x003F; // U+003F QUESTION MARK (?)
const U = 0x0075; // U+0075 LATIN SMALL LETTER U (u)
function isDelim(token, code) {
return token !== null && token.type === types.Delim && token.value.charCodeAt(0) === code;
}
function startsWith(token, code) {
return token.value.charCodeAt(0) === code;
}
function hexSequence(token, offset, allowDash) {
let hexlen = 0;
for (let pos = offset; pos < token.value.length; pos++) {
const code = token.value.charCodeAt(pos);
if (code === HYPHENMINUS && allowDash && hexlen !== 0) {
hexSequence(token, offset + hexlen + 1, false);
return 6; // dissallow following question marks
}
if (!charCodeDefinitions.isHexDigit(code)) {
return 0; // not a hex digit
}
if (++hexlen > 6) {
return 0; // too many hex digits
} }
return hexlen;
}
function withQuestionMarkSequence(consumed, length, getNextToken) {
if (!consumed) {
return 0; // nothing consumed
}
while (isDelim(getNextToken(length), QUESTIONMARK)) {
if (++consumed > 6) {
return 0; // too many question marks
}
length++;
}
return length;
}
// https://drafts.csswg.org/css-syntax/#urange
// Informally, the <urange> production has three forms:
// U+0001
// Defines a range consisting of a single code point, in this case the code point "1".
// U+0001-00ff
// Defines a range of codepoints between the first and the second value, in this case
// the range between "1" and "ff" (255 in decimal) inclusive.
// U+00??
// Defines a range of codepoints where the "?" characters range over all hex digits,
// in this case defining the same as the value U+0000-00ff.
// In each form, a maximum of 6 digits is allowed for each hexadecimal number (if you treat "?" as a hexadecimal digit).
//
// <urange> =
// u '+' <ident-token> '?'* |
// u <dimension-token> '?'* |
// u <number-token> '?'* |
// u <number-token> <dimension-token> |
// u <number-token> <number-token> |
// u '+' '?'+
function urange(token, getNextToken) {
let length = 0;
// should start with `u` or `U`
if (token === null || token.type !== types.Ident || !utils.cmpChar(token.value, 0, U)) {
return 0;
}
token = getNextToken(++length);
if (token === null) {
return 0;
}
// u '+' <ident-token> '?'*
// u '+' '?'+
if (isDelim(token, PLUSSIGN)) {
token = getNextToken(++length);
if (token === null) {
return 0;
}
if (token.type === types.Ident) {
// u '+' <ident-token> '?'*
return withQuestionMarkSequence(hexSequence(token, 0, true), ++length, getNextToken);
}
if (isDelim(token, QUESTIONMARK)) {
// u '+' '?'+
return withQuestionMarkSequence(1, ++length, getNextToken);
}
// Hex digit or question mark is expected
return 0;
}
// u <number-token> '?'*
// u <number-token> <dimension-token>
// u <number-token> <number-token>
if (token.type === types.Number) {
const consumedHexLength = hexSequence(token, 1, true);
if (consumedHexLength === 0) {
return 0;
}
token = getNextToken(++length);
if (token === null) {
// u <number-token> <eof>
return length;
}
if (token.type === types.Dimension || token.type === types.Number) {
// u <number-token> <dimension-token>
// u <number-token> <number-token>
if (!startsWith(token, HYPHENMINUS) || !hexSequence(token, 1, false)) {
return 0;
}
return length + 1;
}
// u <number-token> '?'*
return withQuestionMarkSequence(consumedHexLength, length, getNextToken);
}
// u <dimension-token> '?'*
if (token.type === types.Dimension) {
return withQuestionMarkSequence(hexSequence(token, 1, true), ++length, getNextToken);
}
return 0;
}
module.exports = urange;