54 lines
1.6 KiB
JavaScript
54 lines
1.6 KiB
JavaScript
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import { walk } from 'css-tree';
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import {
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unsafeToSkipNode,
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isEqualSelectors,
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isEqualDeclarations,
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addSelectors,
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hasSimilarSelectors
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} from './utils.js';
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function processRule(node, item, list) {
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const selectors = node.prelude.children;
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const declarations = node.block.children;
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list.prevUntil(item.prev, function(prev) {
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// skip non-ruleset node if safe
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if (prev.type !== 'Rule') {
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return unsafeToSkipNode.call(selectors, prev);
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}
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const prevSelectors = prev.prelude.children;
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const prevDeclarations = prev.block.children;
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// try to join rulesets with equal pseudo signature
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if (node.pseudoSignature === prev.pseudoSignature) {
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// try to join by selectors
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if (isEqualSelectors(prevSelectors, selectors)) {
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prevDeclarations.appendList(declarations);
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list.remove(item);
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return true;
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}
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// try to join by declarations
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if (isEqualDeclarations(declarations, prevDeclarations)) {
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addSelectors(prevSelectors, selectors);
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list.remove(item);
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return true;
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}
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}
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// go to prev ruleset if has no selector similarities
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return hasSimilarSelectors(selectors, prevSelectors);
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});
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}
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// NOTE: direction should be left to right, since rulesets merge to left
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// ruleset. When direction right to left unmerged rulesets may prevent lookup
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// TODO: remove initial merge
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export default function initialMergeRule(ast) {
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walk(ast, {
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visit: 'Rule',
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enter: processRule
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});
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};
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