var walk = require('css-tree').walk;
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var utils = require('./utils');
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/*
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At this step all rules has single simple selector. We try to join by equal
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declaration blocks to first rule, e.g.
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.a { color: red }
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b { ... }
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.b { color: red }
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->
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.a, .b { color: red }
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b { ... }
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*/
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function processRule(node, item, list) {
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var selectors = node.prelude.children;
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var declarations = node.block.children;
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var nodeCompareMarker = selectors.first().compareMarker;
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var skippedCompareMarkers = {};
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list.nextUntil(item.next, function(next, nextItem) {
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// skip non-ruleset node if safe
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if (next.type !== 'Rule') {
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return utils.unsafeToSkipNode.call(selectors, next);
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}
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if (node.pseudoSignature !== next.pseudoSignature) {
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return true;
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}
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var nextFirstSelector = next.prelude.children.head;
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var nextDeclarations = next.block.children;
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var nextCompareMarker = nextFirstSelector.data.compareMarker;
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// if next ruleset has same marked as one of skipped then stop joining
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if (nextCompareMarker in skippedCompareMarkers) {
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return true;
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}
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// try to join by selectors
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if (selectors.head === selectors.tail) {
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if (selectors.first().id === nextFirstSelector.data.id) {
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declarations.appendList(nextDeclarations);
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list.remove(nextItem);
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return;
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}
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}
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// try to join by properties
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if (utils.isEqualDeclarations(declarations, nextDeclarations)) {
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var nextStr = nextFirstSelector.data.id;
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selectors.some(function(data, item) {
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var curStr = data.id;
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if (nextStr < curStr) {
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selectors.insert(nextFirstSelector, item);
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return true;
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}
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if (!item.next) {
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selectors.insert(nextFirstSelector);
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return true;
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}
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});
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list.remove(nextItem);
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return;
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}
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// go to next ruleset if current one can be skipped (has no equal specificity nor element selector)
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if (nextCompareMarker === nodeCompareMarker) {
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return true;
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}
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skippedCompareMarkers[nextCompareMarker] = true;
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});
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}
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module.exports = function mergeRule(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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