41 lines
1.5 KiB
JavaScript
41 lines
1.5 KiB
JavaScript
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import { getElementParent } from "./querying.js";
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/**
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* Some selectors such as `:contains` and (non-relative) `:has` will only be
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* able to match elements if their parents match the selector (as they contain
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* a subset of the elements that the parent contains).
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*
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* This function wraps the given `matches` function in a function that caches
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* the results of the parent elements, so that the `matches` function only
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* needs to be called once for each subtree.
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*/
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export function cacheParentResults(next, { adapter, cacheResults }, matches) {
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if (cacheResults === false || typeof WeakMap === "undefined") {
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return (elem) => next(elem) && matches(elem);
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}
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// Use a cache to avoid re-checking children of an element.
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// @ts-expect-error `Node` is not extending object
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const resultCache = new WeakMap();
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function addResultToCache(elem) {
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const result = matches(elem);
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resultCache.set(elem, result);
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return result;
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}
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return function cachedMatcher(elem) {
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if (!next(elem))
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return false;
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if (resultCache.has(elem)) {
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return resultCache.get(elem);
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}
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// Check all of the element's parents.
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let node = elem;
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do {
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const parent = getElementParent(node, adapter);
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if (parent === null) {
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return addResultToCache(elem);
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}
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node = parent;
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} while (!resultCache.has(node));
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return resultCache.get(node) && addResultToCache(elem);
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};
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}
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//# sourceMappingURL=cache.js.map
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