1 files changed, 48 insertions, 0 deletions
diff --git a/node_modules/csso/lib/compressor/restructure/1-initialMergeRuleset.js b/node_modules/csso/lib/compressor/restructure/1-initialMergeRuleset.js
new file mode 100644
index 00000000..036a04b4
--- /dev/null
+++ b/node_modules/csso/lib/compressor/restructure/1-initialMergeRuleset.js
@@ -0,0 +1,48 @@
+var utils = require('./utils.js');
+var walkRules = require('../../utils/walk.js').rules;
+
+function processRuleset(node, item, list) {
+    var selectors = node.selector.selectors;
+    var declarations = node.block.declarations;
+
+    list.prevUntil(item.prev, function(prev) {
+        // skip non-ruleset node if safe
+        if (prev.type !== 'Ruleset') {
+            return utils.unsafeToSkipNode.call(selectors, prev);
+        }
+
+        var prevSelectors = prev.selector.selectors;
+        var prevDeclarations = prev.block.declarations;
+
+        // try to join rulesets with equal pseudo signature
+        if (node.pseudoSignature === prev.pseudoSignature) {
+            // try to join by selectors
+            if (utils.isEqualLists(prevSelectors, selectors)) {
+                prevDeclarations.appendList(declarations);
+                list.remove(item);
+                return true;
+            }
+
+            // try to join by declarations
+            if (utils.isEqualDeclarations(declarations, prevDeclarations)) {
+                utils.addSelectors(prevSelectors, selectors);
+                list.remove(item);
+                return true;
+            }
+        }
+
+        // go to prev ruleset if has no selector similarities
+        return utils.hasSimilarSelectors(selectors, prevSelectors);
+    });
+};
+
+// NOTE: direction should be left to right, since rulesets merge to left
+// ruleset. When direction right to left unmerged rulesets may prevent lookup
+// TODO: remove initial merge
+module.exports = function initialMergeRuleset(ast) {
+    walkRules(ast, function(node, item, list) {
+        if (node.type === 'Ruleset') {
+            processRuleset(node, item, list);
+        }
+    });
+};