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