IDEA-218391 Transform to single return: remove excessive braces in if-else chains.

GitOrigin-RevId: b13d36218843ae5ff7fbfbcadc898113ad4c9bc1

java/java-impl/src/com/intellij/codeInsight/intention/impl/singlereturn/ReturnReplacementContext.java

@@ -289,34 +289,53 @@ class ReturnReplacementContext {
     }
     PsiCodeBlock block = tryCast(myReturnStatement.getParent(), PsiCodeBlock.class);
     new CommentTracker().deleteAndRestoreComments(myReturnStatement);
-    cleanUpEmptyBlocks(block);
+    PsiElement place = cleanUpEmptyBlocks(block);
+    stripUnnecessaryBlocks(place);
   }
 
-  private static void cleanUpEmptyBlocks(PsiCodeBlock block) {
-    if (block == null || !block.isEmpty()) return;
+  private void stripUnnecessaryBlocks(PsiElement place) {
+    while (place != null && place != myBlock) {
+      if (place instanceof PsiBlockStatement) {
+        PsiIfStatement parentIf = tryCast(place.getParent(), PsiIfStatement.class);
+        if (parentIf != null && parentIf.getElseBranch() == place) {
+          PsiIfStatement childIf = tryCast(ControlFlowUtils.stripBraces((PsiStatement)place), PsiIfStatement.class);
+          if (childIf != null) {
+            place = place.replace(childIf);
+          }
+        }
+      }
+      place = place.getParent();
+    }
+  }
+
+  private static PsiElement cleanUpEmptyBlocks(PsiCodeBlock block) {
+    if (block == null || !block.isEmpty()) return block;
     PsiBlockStatement blockStatement = tryCast(block.getParent(), PsiBlockStatement.class);
-    if (blockStatement == null) return;
+    if (blockStatement == null) return block;
     PsiIfStatement parent = tryCast(blockStatement.getParent(), PsiIfStatement.class);
-    if (parent == null) return;
+    if (parent == null) return block;
     PsiExpression condition = parent.getCondition();
-    if (condition == null) return;
+    if (condition == null) return block;
     if (blockStatement == parent.getElseBranch()) {
       new CommentTracker().deleteAndRestoreComments(blockStatement);
+      return parent;
     }
-    else if (blockStatement == parent.getThenBranch()) {
+    if (blockStatement == parent.getThenBranch()) {
       if (parent.getElseBranch() != null) {
         new CommentTracker().replaceAndRestoreComments(blockStatement, parent.getElseBranch());
         parent.getElseBranch().delete();
         CommentTracker ct = new CommentTracker();
         String negatedCondition = BoolUtils.getNegatedExpressionText(condition, ct);
         ct.replaceAndRestoreComments(condition, negatedCondition);
+        return parent;
       }
-      else if (!SideEffectChecker.mayHaveSideEffects(condition)) {
+      if (!SideEffectChecker.mayHaveSideEffects(condition)) {
         PsiCodeBlock parentBlock = tryCast(parent.getParent(), PsiCodeBlock.class);
         new CommentTracker().deleteAndRestoreComments(parent);
-        cleanUpEmptyBlocks(parentBlock);
+        return cleanUpEmptyBlocks(parentBlock);
       }
     }
+    return block;
   }
 
   static void replaceSingleReturn(@NotNull Project project,

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/convertToSingleReturn/afterBooleanNestedIf.java

@@ -12,12 +12,10 @@ class Test {
                 s = arr[1];
                 if (s == null) {
                     result = false;
-                } else {
-                    if (arr.length > 3) {
-                        s = arr[2];
-                        if (s != null && s.isEmpty()) {
-                            result = false;
-                        }
+                } else if (arr.length > 3) {
+                    s = arr[2];
+                    if (s != null && s.isEmpty()) {
+                        result = false;
                     }
                 }
             }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/convertToSingleReturn/afterIntIfs.java

@@ -8,12 +8,10 @@ class Test {
             } else {
                 result = 4;
             }
+        } else if (s.isEmpty()) {
+            result = 3;
         } else {
-            if (s.isEmpty()) {
-                result = 3;
-            } else {
-                System.out.println(s);
-            }
+            System.out.println(s);
         }
         return result;
     }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/convertToSingleReturn/afterSynchronized.java

@@ -5,12 +5,10 @@ class Test {
         synchronized (this) {
             if (x == 0) {
                 result = "foo";
+            } else if (x == 1) {
+                result = "bar";
             } else {
-                if (x == 1) {
-                    result = "bar";
-                } else {
-                    result = "baz";
-                }
+                result = "baz";
             }
         }
         return result;

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/convertToSingleReturn/afterSynchronized2.java

@@ -5,10 +5,8 @@ class Test {
         synchronized (this) {
             if (x == 0) {
                 result = "foo";
-            } else {
-                if (x == 1) {
-                    result = "bar";
-                }
+            } else if (x == 1) {
+                result = "bar";
             }
         }
         if (result == null) {