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rOACCT/node_modules/clean-css/lib/optimizer/level-2/merge-media-queries.js
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merge-media-queries.js
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			var canReorder = require('./reorderable').canReorder;
			var canReorderSingle = require('./reorderable').canReorderSingle;
			var extractProperties = require('./extract-properties');
			var rulesOverlap = require('./rules-overlap');

			var serializeRules = require('../../writer/one-time').rules;
			var OptimizationLevel = require('../../options/optimization-level').OptimizationLevel;
			var Token = require('../../tokenizer/token');

			function mergeMediaQueries(tokens, context) {
			var mergeSemantically = context.options.level[OptimizationLevel.Two].mergeSemantically;
			var specificityCache = context.cache.specificity;
			var candidates = {};
			var reduced = [];

			for (var i = tokens.length - 1; i >= 0; i--) {
			var token = tokens[i];
			if (token[0] != Token.NESTED_BLOCK) {
			continue;
			}

			var key = serializeRules(token[1]);
			var candidate = candidates[key];
			if (!candidate) {
			candidate = [];
			candidates[key] = candidate;
			}

			candidate.push(i);
			}

			for (var name in candidates) {
			var positions = candidates[name];

			positionLoop:
			for (var j = positions.length - 1; j > 0; j--) {
			var positionOne = positions[j];
			var tokenOne = tokens[positionOne];
			var positionTwo = positions[j - 1];
			var tokenTwo = tokens[positionTwo];

			directionLoop:
			for (var direction = 1; direction >= -1; direction -= 2) {
			var topToBottom = direction == 1;
			var from = topToBottom ? positionOne + 1 : positionTwo - 1;
			var to = topToBottom ? positionTwo : positionOne;
			var delta = topToBottom ? 1 : -1;
			var source = topToBottom ? tokenOne : tokenTwo;
			var target = topToBottom ? tokenTwo : tokenOne;
			var movedProperties = extractProperties(source);

			while (from != to) {
			var traversedProperties = extractProperties(tokens[from]);
			from += delta;

			if (mergeSemantically
			&& allSameRulePropertiesCanBeReordered(movedProperties, traversedProperties, specificityCache)
			) {
			continue;
			}

			if (!canReorder(movedProperties, traversedProperties, specificityCache)) { continue directionLoop; }
			}

			target[2] = topToBottom
			? source[2].concat(target[2])
			: target[2].concat(source[2]);
			source[2] = [];

			reduced.push(target);
			continue positionLoop;
			}
			}
			}

			return reduced;
			}

			function allSameRulePropertiesCanBeReordered(movedProperties, traversedProperties, specificityCache) {
			var movedProperty;
			var movedRule;
			var traversedProperty;
			var traversedRule;
			var i, l;
			var j, m;

			for (i = 0, l = movedProperties.length; i < l; i++) {
			movedProperty = movedProperties[i];
			movedRule = movedProperty[5];

			for (j = 0, m = traversedProperties.length; j < m; j++) {
			traversedProperty = traversedProperties[j];
			traversedRule = traversedProperty[5];

			if (rulesOverlap(movedRule, traversedRule, true)
			&& !canReorderSingle(movedProperty, traversedProperty, specificityCache)) {
			return false;
			}
			}
			}

			return true;
			}

			module.exports = mergeMediaQueries;