47 lines
1.2 KiB
JavaScript
47 lines
1.2 KiB
JavaScript
import { invariant } from './utils';
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/**
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* https://tc39.es/ecma402/#sec-unicodeextensionvalue
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* @param extension
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* @param key
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*/
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export function UnicodeExtensionValue(extension, key) {
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invariant(key.length === 2, 'key must have 2 elements');
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var size = extension.length;
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var searchValue = "-".concat(key, "-");
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var pos = extension.indexOf(searchValue);
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if (pos !== -1) {
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var start = pos + 4;
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var end = start;
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var k = start;
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var done = false;
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while (!done) {
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var e = extension.indexOf('-', k);
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var len = void 0;
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if (e === -1) {
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len = size - k;
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}
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else {
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len = e - k;
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}
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if (len === 2) {
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done = true;
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}
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else if (e === -1) {
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end = size;
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done = true;
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}
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else {
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end = e;
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k = e + 1;
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}
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}
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return extension.slice(start, end);
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}
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searchValue = "-".concat(key);
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pos = extension.indexOf(searchValue);
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if (pos !== -1 && pos + 3 === size) {
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return '';
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}
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return undefined;
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}
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