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