update

node_modules/clean-css/lib/optimizer/level-2/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;