b661614265
* enabled `optimizeUniversalDefaults` by default
This PR is done in a way so that the default is set to `true`, but you
can still disable it if it causes issues. In this case we do appreciate
an issue in that case 😅.
* update tests to use optimized universal selector
* update integration tests
* add dedicated tests for the optimized universal selector
* improve minimumImpactSelector algorithm
I think I cracked the algorithm, but I will probably need another pair
of eyes on the subject.
The current implementation works like this:
Prerequisites:
- The selector should already have been parsed using the selectorParser
from 'postcss-selector-parser'.
Algorithm:
1. Remove all of the pseudo classes from the list of nodes.
1.1. We do want to keep pseudo elements (E.g.: `::before`, `::first-line`, ...)
1.2. We do want to keep pseudo classes that contain nodes (E.g.:
`:not(...)`)
2. Reverse the list of nodes.
This will make it easier to search from the end to the start. For
example `.group:hover .group-hover` should result in `.group-hover`
not `.group`.
2.1. Find the index of the best match (class, id, attribute), and
convert the node if required. (E.g.: `span#app` -> `#app` => `[id="app"]`)
2.2. Remove the rest of the selector that is not important anymore
2.3. Re-join the left-over nodes together
* update tests using new algorithm
* also look for `tag` types
* take `tag` into account
* simplify logic
* add test to prove `rest.reverse()` in first case is required
In case we don't find a match (idx === -1), we use `rest.reverse()`.
However, it looks like you can just use `nodes` instead.
This is not entirely true, because the `rest` variable will contain only
the nodes that are not pseudo elements.
`*:hover` would result in `*:hover` instead of just `*`
* replace all nodes after > with a single universal selector
121 lines
3.1 KiB
JavaScript
121 lines
3.1 KiB
JavaScript
import postcss from 'postcss'
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import selectorParser from 'postcss-selector-parser'
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import { flagEnabled } from '../featureFlags'
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let getNode = {
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id(node) {
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return selectorParser.attribute({
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attribute: 'id',
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operator: '=',
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value: node.value,
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quoteMark: '"',
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})
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},
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}
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function minimumImpactSelector(nodes) {
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let rest = nodes
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.filter((node) => {
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// Keep non-pseudo nodes
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if (node.type !== 'pseudo') return true
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// Keep pseudo nodes that have subnodes
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// E.g.: `:not()` contains subnodes inside the parentheses
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if (node.nodes.length > 0) return true
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// Keep pseudo `elements`
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// This implicitly means that we ignore pseudo `classes`
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return (
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node.value.startsWith('::') ||
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[':before', ':after', ':first-line', ':first-letter'].includes(node.value)
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)
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})
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.reverse()
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let searchFor = new Set(['tag', 'class', 'id', 'attribute'])
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let splitPointIdx = rest.findIndex((n) => searchFor.has(n.type))
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if (splitPointIdx === -1) return rest.reverse().join('').trim()
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let node = rest[splitPointIdx]
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let bestNode = getNode[node.type] ? getNode[node.type](node) : node
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rest = rest.slice(0, splitPointIdx)
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let combinatorIdx = rest.findIndex((n) => n.type === 'combinator' && n.value === '>')
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if (combinatorIdx !== -1) {
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rest.splice(0, combinatorIdx)
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rest.unshift(selectorParser.universal())
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}
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return [bestNode, ...rest.reverse()].join('').trim()
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}
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export let elementSelectorParser = selectorParser((selectors) => {
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return selectors.map((s) => {
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let nodes = s.split((n) => n.type === 'combinator' && n.value === ' ').pop()
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return minimumImpactSelector(nodes)
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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 resolveDefaultsAtRules({ tailwindConfig }) {
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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 && 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 rules = variableNodeMap.get(universal.params) ?? []
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for (let rule of rules) {
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for (let selector of extractElementSelector(rule.selector)) {
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selectors.add(selector)
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}
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}
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if (selectors.size === 0) {
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universal.remove()
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continue
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}
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let universalRule = postcss.rule()
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if (flagEnabled(tailwindConfig, 'optimizeUniversalDefaults')) {
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universalRule.selectors = [...selectors]
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} else {
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universalRule.selectors = ['*', '::before', '::after']
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}
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universalRule.append(universal.nodes)
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universal.before(universalRule)
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universal.remove()
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}
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}
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}
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