67 lines
1.9 KiB
JavaScript
67 lines
1.9 KiB
JavaScript
'use strict';
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const selectorParser = require('postcss-selector-parser');
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/**
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* @param {string} selectors
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* @return {string}
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*/
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function generateUniqueSelector(selectors) {
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/** @type {Map<string, string>} */
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const uniqueSelectors = new Map();
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/** @type {selectorParser.SyncProcessor<void>} */
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const collectUniqueSelectors = (selNode) => {
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for (const node of selNode.nodes) {
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/** @type {string[]} */
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const comments = [];
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// Duplicates are removed by stripping the comments and using the results as the Map key.
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const keyNode = node.clone();
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keyNode.walk((sel) => {
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if (sel.type === 'comment') {
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comments.push(sel.value);
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sel.remove();
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}
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});
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const key = keyNode.toString().trim();
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const dupeSelector = uniqueSelectors.get(key);
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if (!dupeSelector) {
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uniqueSelectors.set(key, node.toString());
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} else if (comments.length) {
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// If the duplicate selector has a comment, it is concatenated to the end of the selector.
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uniqueSelectors.set(key, `${dupeSelector}${comments.join('')}`);
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}
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}
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};
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selectorParser(collectUniqueSelectors).processSync(selectors);
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return [...uniqueSelectors.entries()]
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.sort(([a], [b]) => (a > b ? 1 : a < b ? -1 : 0))
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.map(([, selector]) => selector)
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.join();
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}
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/**
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* @type {import('postcss').PluginCreator<void>}
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* @return {import('postcss').Plugin}
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*/
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function pluginCreator() {
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return {
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postcssPlugin: 'postcss-unique-selectors',
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OnceExit(css) {
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css.walkRules((nodes) => {
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if (nodes.raws.selector && nodes.raws.selector.raw) {
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nodes.raws.selector.raw = generateUniqueSelector(
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nodes.raws.selector.raw
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);
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} else {
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nodes.selector = generateUniqueSelector(nodes.selector);
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}
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});
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},
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};
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}
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pluginCreator.postcss = true;
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module.exports = pluginCreator;
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