UnicodeRange.cjs•4.54 kB
'use strict';
const types = require('../../tokenizer/types.cjs');
const charCodeDefinitions = require('../../tokenizer/char-code-definitions.cjs');
const PLUSSIGN = 0x002B; // U+002B PLUS SIGN (+)
const HYPHENMINUS = 0x002D; // U+002D HYPHEN-MINUS (-)
const QUESTIONMARK = 0x003F; // U+003F QUESTION MARK (?)
function eatHexSequence(offset, allowDash) {
let len = 0;
for (let pos = this.tokenStart + offset; pos < this.tokenEnd; pos++) {
const code = this.charCodeAt(pos);
if (code === HYPHENMINUS && allowDash && len !== 0) {
eatHexSequence.call(this, offset + len + 1, false);
return -1;
}
if (!charCodeDefinitions.isHexDigit(code)) {
this.error(
allowDash && len !== 0
? 'Hyphen minus' + (len < 6 ? ' or hex digit' : '') + ' is expected'
: (len < 6 ? 'Hex digit is expected' : 'Unexpected input'),
pos
);
}
if (++len > 6) {
this.error('Too many hex digits', pos);
} }
this.next();
return len;
}
function eatQuestionMarkSequence(max) {
let count = 0;
while (this.isDelim(QUESTIONMARK)) {
if (++count > max) {
this.error('Too many question marks');
}
this.next();
}
}
function startsWith(code) {
if (this.charCodeAt(this.tokenStart) !== code) {
this.error((code === PLUSSIGN ? 'Plus sign' : 'Hyphen minus') + ' is expected');
}
}
// 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 scanUnicodeRange() {
let hexLength = 0;
switch (this.tokenType) {
case types.Number:
// u <number-token> '?'*
// u <number-token> <dimension-token>
// u <number-token> <number-token>
hexLength = eatHexSequence.call(this, 1, true);
if (this.isDelim(QUESTIONMARK)) {
eatQuestionMarkSequence.call(this, 6 - hexLength);
break;
}
if (this.tokenType === types.Dimension ||
this.tokenType === types.Number) {
startsWith.call(this, HYPHENMINUS);
eatHexSequence.call(this, 1, false);
break;
}
break;
case types.Dimension:
// u <dimension-token> '?'*
hexLength = eatHexSequence.call(this, 1, true);
if (hexLength > 0) {
eatQuestionMarkSequence.call(this, 6 - hexLength);
}
break;
default:
// u '+' <ident-token> '?'*
// u '+' '?'+
this.eatDelim(PLUSSIGN);
if (this.tokenType === types.Ident) {
hexLength = eatHexSequence.call(this, 0, true);
if (hexLength > 0) {
eatQuestionMarkSequence.call(this, 6 - hexLength);
}
break;
}
if (this.isDelim(QUESTIONMARK)) {
this.next();
eatQuestionMarkSequence.call(this, 5);
break;
}
this.error('Hex digit or question mark is expected');
}
}
const name = 'UnicodeRange';
const structure = {
value: String
};
function parse() {
const start = this.tokenStart;
// U or u
this.eatIdent('u');
scanUnicodeRange.call(this);
return {
type: 'UnicodeRange',
loc: this.getLocation(start, this.tokenStart),
value: this.substrToCursor(start)
};
}
function generate(node) {
this.tokenize(node.value);
}
exports.generate = generate;
exports.name = name;
exports.parse = parse;
exports.structure = structure;