utils.js•7.82 kB
import {
isDigit,
isHexDigit,
isUppercaseLetter,
isName,
isWhiteSpace,
isValidEscape
} from './char-code-definitions.js';
function getCharCode(source, offset) {
return offset < source.length ? source.charCodeAt(offset) : 0;
}
export function getNewlineLength(source, offset, code) {
if (code === 13 /* \r */ && getCharCode(source, offset + 1) === 10 /* \n */) {
return 2;
}
return 1;
}
export function cmpChar(testStr, offset, referenceCode) {
let code = testStr.charCodeAt(offset);
// code.toLowerCase() for A..Z
if (isUppercaseLetter(code)) {
code = code | 32;
}
return code === referenceCode;
}
export function cmpStr(testStr, start, end, referenceStr) {
if (end - start !== referenceStr.length) {
return false;
}
if (start < 0 || end > testStr.length) {
return false;
}
for (let i = start; i < end; i++) {
const referenceCode = referenceStr.charCodeAt(i - start);
let testCode = testStr.charCodeAt(i);
// testCode.toLowerCase() for A..Z
if (isUppercaseLetter(testCode)) {
testCode = testCode | 32;
}
if (testCode !== referenceCode) {
return false;
}
}
return true;
}
export function findWhiteSpaceStart(source, offset) {
for (; offset >= 0; offset--) {
if (!isWhiteSpace(source.charCodeAt(offset))) {
break;
}
}
return offset + 1;
}
export function findWhiteSpaceEnd(source, offset) {
for (; offset < source.length; offset++) {
if (!isWhiteSpace(source.charCodeAt(offset))) {
break;
}
}
return offset;
}
export function findDecimalNumberEnd(source, offset) {
for (; offset < source.length; offset++) {
if (!isDigit(source.charCodeAt(offset))) {
break;
}
}
return offset;
}
// § 4.3.7. Consume an escaped code point
export function consumeEscaped(source, offset) {
// It assumes that the U+005C REVERSE SOLIDUS (\) has already been consumed and
// that the next input code point has already been verified to be part of a valid escape.
offset += 2;
// hex digit
if (isHexDigit(getCharCode(source, offset - 1))) {
// Consume as many hex digits as possible, but no more than 5.
// Note that this means 1-6 hex digits have been consumed in total.
for (const maxOffset = Math.min(source.length, offset + 5); offset < maxOffset; offset++) {
if (!isHexDigit(getCharCode(source, offset))) {
break;
}
}
// If the next input code point is whitespace, consume it as well.
const code = getCharCode(source, offset);
if (isWhiteSpace(code)) {
offset += getNewlineLength(source, offset, code);
}
}
return offset;
}
// §4.3.11. Consume a name
// Note: This algorithm does not do the verification of the first few code points that are necessary
// to ensure the returned code points would constitute an <ident-token>. If that is the intended use,
// ensure that the stream starts with an identifier before calling this algorithm.
export function consumeName(source, offset) {
// Let result initially be an empty string.
// Repeatedly consume the next input code point from the stream:
for (; offset < source.length; offset++) {
const code = source.charCodeAt(offset);
// name code point
if (isName(code)) {
// Append the code point to result.
continue;
}
// the stream starts with a valid escape
if (isValidEscape(code, getCharCode(source, offset + 1))) {
// Consume an escaped code point. Append the returned code point to result.
offset = consumeEscaped(source, offset) - 1;
continue;
}
// anything else
// Reconsume the current input code point. Return result.
break;
}
return offset;
}
// §4.3.12. Consume a number
export function consumeNumber(source, offset) {
let code = source.charCodeAt(offset);
// 2. If the next input code point is U+002B PLUS SIGN (+) or U+002D HYPHEN-MINUS (-),
// consume it and append it to repr.
if (code === 0x002B || code === 0x002D) {
code = source.charCodeAt(offset += 1);
}
// 3. While the next input code point is a digit, consume it and append it to repr.
if (isDigit(code)) {
offset = findDecimalNumberEnd(source, offset + 1);
code = source.charCodeAt(offset);
}
// 4. If the next 2 input code points are U+002E FULL STOP (.) followed by a digit, then:
if (code === 0x002E && isDigit(source.charCodeAt(offset + 1))) {
// 4.1 Consume them.
// 4.2 Append them to repr.
offset += 2;
// 4.3 Set type to "number".
// TODO
// 4.4 While the next input code point is a digit, consume it and append it to repr.
offset = findDecimalNumberEnd(source, offset);
}
// 5. If the next 2 or 3 input code points are U+0045 LATIN CAPITAL LETTER E (E)
// or U+0065 LATIN SMALL LETTER E (e), ... , followed by a digit, then:
if (cmpChar(source, offset, 101 /* e */)) {
let sign = 0;
code = source.charCodeAt(offset + 1);
// ... optionally followed by U+002D HYPHEN-MINUS (-) or U+002B PLUS SIGN (+) ...
if (code === 0x002D || code === 0x002B) {
sign = 1;
code = source.charCodeAt(offset + 2);
}
// ... followed by a digit
if (isDigit(code)) {
// 5.1 Consume them.
// 5.2 Append them to repr.
// 5.3 Set type to "number".
// TODO
// 5.4 While the next input code point is a digit, consume it and append it to repr.
offset = findDecimalNumberEnd(source, offset + 1 + sign + 1);
}
}
return offset;
}
// § 4.3.14. Consume the remnants of a bad url
// ... its sole use is to consume enough of the input stream to reach a recovery point
// where normal tokenizing can resume.
export function consumeBadUrlRemnants(source, offset) {
// Repeatedly consume the next input code point from the stream:
for (; offset < source.length; offset++) {
const code = source.charCodeAt(offset);
// U+0029 RIGHT PARENTHESIS ())
// EOF
if (code === 0x0029) {
// Return.
offset++;
break;
}
if (isValidEscape(code, getCharCode(source, offset + 1))) {
// Consume an escaped code point.
// Note: This allows an escaped right parenthesis ("\)") to be encountered
// without ending the <bad-url-token>. This is otherwise identical to
// the "anything else" clause.
offset = consumeEscaped(source, offset);
}
}
return offset;
}
// § 4.3.7. Consume an escaped code point
// Note: This algorithm assumes that escaped is valid without leading U+005C REVERSE SOLIDUS (\)
export function decodeEscaped(escaped) {
// Single char escaped that's not a hex digit
if (escaped.length === 1 && !isHexDigit(escaped.charCodeAt(0))) {
return escaped[0];
}
// Interpret the hex digits as a hexadecimal number.
let code = parseInt(escaped, 16);
if (
(code === 0) || // If this number is zero,
(code >= 0xD800 && code <= 0xDFFF) || // or is for a surrogate,
(code > 0x10FFFF) // or is greater than the maximum allowed code point
) {
// ... return U+FFFD REPLACEMENT CHARACTER
code = 0xFFFD;
}
// Otherwise, return the code point with that value.
return String.fromCodePoint(code);
}