66 lines
1.5 KiB
JavaScript
66 lines
1.5 KiB
JavaScript
import postcss from 'postcss'
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import selectorParser from 'postcss-selector-parser'
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let elementSelectorParser = selectorParser((selectors) => {
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return selectors.map((s) => {
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return s
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.split((n) => n.type === 'combinator')
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.pop()
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.filter((n) => n.type !== 'pseudo' || n.value.startsWith('::'))
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.join('')
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.trim()
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})
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})
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let cache = new Map()
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function extractElementSelector(selector) {
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if (!cache.has(selector)) {
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cache.set(selector, elementSelectorParser.transformSync(selector))
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}
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return cache.get(selector)
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}
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export default function collapseAdjacentRules() {
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return (root) => {
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let variableNodeMap = new Map()
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let universals = new Set()
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root.walkAtRules('defaults', (rule) => {
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if (rule.nodes.length > 0) {
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universals.add(rule)
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return
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}
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let variable = rule.params
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if (!variableNodeMap.has(variable)) {
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variableNodeMap.set(variable, new Set())
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}
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variableNodeMap.get(variable).add(rule.parent)
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rule.remove()
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})
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for (let universal of universals) {
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let selectors = new Set()
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let rule = postcss.rule()
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universal.walkDecls((decl) => {
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let variable = decl.prop
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for (let node of variableNodeMap.get(variable) ?? []) {
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for (let selector of extractElementSelector(node.selector)) {
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selectors.add(selector)
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}
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}
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})
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rule.selectors = [...selectors]
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rule.append(universal.clone().nodes)
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universal.before(rule)
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universal.remove()
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}
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}
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}
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