IDEA-19061 Integrate the Rearranger-plugin into core-IDE

Correct tree merge when non-first rule should be merged down

java/java-tests/testSrc/com/intellij/application/options/codeStyle/arrangement/ArrangementConfigUtilTest.groovy

@@ -139,6 +139,40 @@ node =  '4'()
     checkRowMappings([:], rowMappings)
   }
   
+    @Test
+  void replaceWithTwoLevelMergeToNodeBelow() {
+        // Init.
+    def from;
+    def to;
+    def initial = new TreeNodeBuilder().
+      '0' {
+from =  '1'() {
+          '2'()
+to =      '3'()}
+        '4'() {
+          '5'() }        
+      }
+    
+    // Modify.
+    def replacement = new TreeNodeBuilder().
+      '4' {
+        '3'()
+      }
+    def rowMappings = doReplace(initial, from, to, replacement)
+    
+    // Check.
+    def expected = new TreeNodeBuilder().
+      '0' {
+        '1' {
+          '2'()}
+        '4' {
+          '3'()
+          '5'()}
+      }
+    assertNodesEqual(expected, initial)
+    checkRowMappings([:], rowMappings)
+  }
+  
   @Test
   void addWithoutMergeAbove() {
     def initial = new TreeNodeBuilder().

platform/lang-impl/src/com/intellij/application/options/codeStyle/arrangement/ArrangementConfigUtil.java

@@ -341,7 +341,18 @@ public class ArrangementConfigUtil {
     int insertionIndex = root.getChildCount() < childCountBefore ? childCountBefore - 1 : childCountBefore;
     boolean merged = insert(root, insertionIndex, replacement, treeModel);
     if (cutHierarchy != null) {
-      insert(root, insertionIndex + (merged ? 0 : 1), cutHierarchy, treeModel);
+      List<ArrangementTreeNode> toInsert = new ArrayList<ArrangementTreeNode>();
+      if (hasEqualSetting(root, cutHierarchy)) {
+        for (int i = 0; i < cutHierarchy.getChildCount(); i++) {
+          toInsert.add(cutHierarchy.getChildAt(i));
+        }
+      }
+      else {
+        toInsert.add(cutHierarchy);
+      }
+      for (ArrangementTreeNode node : toInsert) {
+        insert(root, root.getChildCount(), node, treeModel);
+      }
     }
     //endregion