generic-an-plus-b.js•6.69 kB
import {
isDigit,
cmpChar,
Delim,
WhiteSpace,
Comment,
Ident,
Number as NumberToken,
Dimension
} from '../tokenizer/index.js';
const PLUSSIGN = 0x002B; // U+002B PLUS SIGN (+)
const HYPHENMINUS = 0x002D; // U+002D HYPHEN-MINUS (-)
const N = 0x006E; // U+006E LATIN SMALL LETTER N (n)
const DISALLOW_SIGN = true;
const ALLOW_SIGN = false;
function isDelim(token, code) {
return token !== null && token.type === Delim && token.value.charCodeAt(0) === code;
}
function skipSC(token, offset, getNextToken) {
while (token !== null && (token.type === WhiteSpace || token.type === Comment)) {
token = getNextToken(++offset);
}
return offset;
}
function checkInteger(token, valueOffset, disallowSign, offset) {
if (!token) {
return 0;
}
const code = token.value.charCodeAt(valueOffset);
if (code === PLUSSIGN || code === HYPHENMINUS) {
if (disallowSign) {
// Number sign is not allowed
return 0;
}
valueOffset++;
}
for (; valueOffset < token.value.length; valueOffset++) {
if (!isDigit(token.value.charCodeAt(valueOffset))) {
// Integer is expected
return 0;
}
}
return offset + 1;
}
// ... <signed-integer>
// ... ['+' | '-'] <signless-integer>
function consumeB(token, offset_, getNextToken) {
let sign = false;
let offset = skipSC(token, offset_, getNextToken);
token = getNextToken(offset);
if (token === null) {
return offset_;
}
if (token.type !== NumberToken) {
if (isDelim(token, PLUSSIGN) || isDelim(token, HYPHENMINUS)) {
sign = true;
offset = skipSC(getNextToken(++offset), offset, getNextToken);
token = getNextToken(offset);
if (token === null || token.type !== NumberToken) {
return 0;
}
} else {
return offset_;
}
}
if (!sign) {
const code = token.value.charCodeAt(0);
if (code !== PLUSSIGN && code !== HYPHENMINUS) {
// Number sign is expected
return 0;
}
}
return checkInteger(token, sign ? 0 : 1, sign, offset);
}
// An+B microsyntax https://www.w3.org/TR/css-syntax-3/#anb
export default function anPlusB(token, getNextToken) {
/* eslint-disable brace-style*/
let offset = 0;
if (!token) {
return 0;
}
// <integer>
if (token.type === NumberToken) {
return checkInteger(token, 0, ALLOW_SIGN, offset); // b
}
// -n
// -n <signed-integer>
// -n ['+' | '-'] <signless-integer>
// -n- <signless-integer>
// <dashndashdigit-ident>
else if (token.type === Ident && token.value.charCodeAt(0) === HYPHENMINUS) {
// expect 1st char is N
if (!cmpChar(token.value, 1, N)) {
return 0;
}
switch (token.value.length) {
// -n
// -n <signed-integer>
// -n ['+' | '-'] <signless-integer>
case 2:
return consumeB(getNextToken(++offset), offset, getNextToken);
// -n- <signless-integer>
case 3:
if (token.value.charCodeAt(2) !== HYPHENMINUS) {
return 0;
}
offset = skipSC(getNextToken(++offset), offset, getNextToken);
token = getNextToken(offset);
return checkInteger(token, 0, DISALLOW_SIGN, offset);
// <dashndashdigit-ident>
default:
if (token.value.charCodeAt(2) !== HYPHENMINUS) {
return 0;
}
return checkInteger(token, 3, DISALLOW_SIGN, offset);
}
}
// '+'? n
// '+'? n <signed-integer>
// '+'? n ['+' | '-'] <signless-integer>
// '+'? n- <signless-integer>
// '+'? <ndashdigit-ident>
else if (token.type === Ident || (isDelim(token, PLUSSIGN) && getNextToken(offset + 1).type === Ident)) {
// just ignore a plus
if (token.type !== Ident) {
token = getNextToken(++offset);
}
if (token === null || !cmpChar(token.value, 0, N)) {
return 0;
}
switch (token.value.length) {
// '+'? n
// '+'? n <signed-integer>
// '+'? n ['+' | '-'] <signless-integer>
case 1:
return consumeB(getNextToken(++offset), offset, getNextToken);
// '+'? n- <signless-integer>
case 2:
if (token.value.charCodeAt(1) !== HYPHENMINUS) {
return 0;
}
offset = skipSC(getNextToken(++offset), offset, getNextToken);
token = getNextToken(offset);
return checkInteger(token, 0, DISALLOW_SIGN, offset);
// '+'? <ndashdigit-ident>
default:
if (token.value.charCodeAt(1) !== HYPHENMINUS) {
return 0;
}
return checkInteger(token, 2, DISALLOW_SIGN, offset);
}
}
// <ndashdigit-dimension>
// <ndash-dimension> <signless-integer>
// <n-dimension>
// <n-dimension> <signed-integer>
// <n-dimension> ['+' | '-'] <signless-integer>
else if (token.type === Dimension) {
let code = token.value.charCodeAt(0);
let sign = code === PLUSSIGN || code === HYPHENMINUS ? 1 : 0;
let i = sign;
for (; i < token.value.length; i++) {
if (!isDigit(token.value.charCodeAt(i))) {
break;
}
}
if (i === sign) {
// Integer is expected
return 0;
}
if (!cmpChar(token.value, i, N)) {
return 0;
}
// <n-dimension>
// <n-dimension> <signed-integer>
// <n-dimension> ['+' | '-'] <signless-integer>
if (i + 1 === token.value.length) {
return consumeB(getNextToken(++offset), offset, getNextToken);
} else {
if (token.value.charCodeAt(i + 1) !== HYPHENMINUS) {
return 0;
}
// <ndash-dimension> <signless-integer>
if (i + 2 === token.value.length) {
offset = skipSC(getNextToken(++offset), offset, getNextToken);
token = getNextToken(offset);
return checkInteger(token, 0, DISALLOW_SIGN, offset);
}
// <ndashdigit-dimension>
else {
return checkInteger(token, i + 2, DISALLOW_SIGN, offset);
}
}
}
return 0;
};