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94 lines
2.1 KiB
94 lines
2.1 KiB
'use strict'; |
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const OVERRIDABLE_RULES = new Set(['keyframes', 'counter-style']); |
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const SCOPE_RULES = new Set(['media', 'supports']); |
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|
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/** |
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* @param {string} prop |
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* @return {string} |
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*/ |
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function vendorUnprefixed(prop) { |
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return prop.replace(/^-\w+-/, ''); |
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} |
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/** |
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* @param {string} name |
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* @return {boolean} |
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*/ |
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function isOverridable(name) { |
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return OVERRIDABLE_RULES.has(vendorUnprefixed(name.toLowerCase())); |
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} |
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/** |
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* @param {string} name |
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* @return {boolean} |
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*/ |
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function isScope(name) { |
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return SCOPE_RULES.has(vendorUnprefixed(name.toLowerCase())); |
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} |
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/** |
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* @param {import('postcss').AtRule} node |
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* @return {string} |
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*/ |
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function getScope(node) { |
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/** @type {import('postcss').Container<import('postcss').ChildNode> | import('postcss').Document | undefined} */ |
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let current = node.parent; |
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const chain = [node.name.toLowerCase(), node.params]; |
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while (current) { |
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if ( |
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current.type === 'atrule' && |
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isScope(/** @type import('postcss').AtRule */ (current).name) |
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) { |
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chain.unshift( |
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/** @type import('postcss').AtRule */ (current).name + |
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' ' + |
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/** @type import('postcss').AtRule */ (current).params |
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); |
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} |
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current = current.parent; |
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} |
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return chain.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-discard-overridden', |
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prepare() { |
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const cache = new Map(); |
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/** @type {{node: import('postcss').AtRule, scope: string}[]} */ |
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const rules = []; |
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return { |
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OnceExit(css) { |
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css.walkAtRules((node) => { |
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if (isOverridable(node.name)) { |
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const scope = getScope(node); |
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cache.set(scope, node); |
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rules.push({ |
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node, |
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scope, |
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}); |
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} |
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}); |
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rules.forEach((rule) => { |
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if (cache.get(rule.scope) !== rule.node) { |
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rule.node.remove(); |
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} |
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}); |
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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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