103 lines
3.3 KiB
JavaScript
103 lines
3.3 KiB
JavaScript
import { AttributeAction, SelectorType, isTraversal as isTraversalBase, } from "css-what";
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export function isTraversal(token) {
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return token.type === "_flexibleDescendant" || isTraversalBase(token);
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}
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/**
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* Sort the parts of the passed selector, as there is potential for
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* optimization (some types of selectors are faster than others).
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*
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* @param arr Selector to sort
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*/
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export function sortRules(arr) {
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const ratings = arr.map(getQuality);
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for (let i = 1; i < arr.length; i++) {
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const procNew = ratings[i];
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if (procNew < 0)
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continue;
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// Use insertion sort to move the token to the correct position.
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for (let j = i; j > 0 && procNew < ratings[j - 1]; j--) {
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const token = arr[j];
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arr[j] = arr[j - 1];
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arr[j - 1] = token;
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ratings[j] = ratings[j - 1];
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ratings[j - 1] = procNew;
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}
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}
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}
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function getAttributeQuality(token) {
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switch (token.action) {
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case AttributeAction.Exists: {
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return 10;
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}
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case AttributeAction.Equals: {
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// Prefer ID selectors (eg. #ID)
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return token.name === "id" ? 9 : 8;
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}
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case AttributeAction.Not: {
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return 7;
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}
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case AttributeAction.Start: {
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return 6;
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}
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case AttributeAction.End: {
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return 6;
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}
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case AttributeAction.Any: {
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return 5;
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}
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case AttributeAction.Hyphen: {
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return 4;
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}
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case AttributeAction.Element: {
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return 3;
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}
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}
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}
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/**
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* Determine the quality of the passed token. The higher the number, the
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* faster the token is to execute.
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*
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* @param token Token to get the quality of.
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* @returns The token's quality.
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*/
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export function getQuality(token) {
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// eslint-disable-next-line @typescript-eslint/switch-exhaustiveness-check
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switch (token.type) {
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case SelectorType.Universal: {
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return 50;
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}
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case SelectorType.Tag: {
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return 30;
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}
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case SelectorType.Attribute: {
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return Math.floor(getAttributeQuality(token) /
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// `ignoreCase` adds some overhead, half the result if applicable.
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(token.ignoreCase ? 2 : 1));
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}
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case SelectorType.Pseudo: {
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return !token.data
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? 3
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: token.name === "has" ||
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token.name === "contains" ||
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token.name === "icontains"
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? // Expensive in any case — run as late as possible.
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0
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: Array.isArray(token.data)
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? // Eg. `:is`, `:not`
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Math.max(
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// If we have traversals, try to avoid executing this selector
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0, Math.min(...token.data.map((d) => Math.min(...d.map(getQuality)))))
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: 2;
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}
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default: {
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return -1;
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}
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}
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}
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export function includesScopePseudo(t) {
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return (t.type === SelectorType.Pseudo &&
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(t.name === "scope" ||
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(Array.isArray(t.data) &&
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t.data.some((data) => data.some(includesScopePseudo)))));
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}
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//# sourceMappingURL=selectors.js.map
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