IDEA-219189 "Split into 2 if's" generates redundant 'else if' clause

GitOrigin-RevId: 0218fd86bb09eea638be20dd96bd248ce498a399

java/java-impl/src/com/intellij/codeInsight/intention/impl/SplitConditionUtil.java

@@ -6,8 +6,10 @@ import com.intellij.psi.*;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.PsiUtil;
+import com.siyeh.ig.psiutils.BoolUtils;
 import com.siyeh.ig.psiutils.CommentTracker;
 import com.siyeh.ig.psiutils.ControlFlowUtils;
+import com.siyeh.ig.psiutils.EquivalenceChecker;
 import com.siyeh.ipp.psiutils.ErrorUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -117,10 +119,21 @@ public class SplitConditionUtil {
       if (nextIf == null) break;
       PsiExpression nextCondition = PsiUtil.skipParenthesizedExprDown(nextIf.getCondition());
       if (nextCondition == null) break;
-      if (PsiEquivalenceUtil.areElementsEquivalent(extract, nextCondition) && nextIf.getThenBranch() != null) {
+      EquivalenceChecker equivalence = EquivalenceChecker.getCanonicalPsiEquivalence();
+      if (nextIf.getThenBranch() == null) break;
+      if (equivalence.expressionsAreEquivalent(extract, nextCondition)) {
         elseChain.add(tracker.text(nextIf.getThenBranch()));
         chainFinished = true;
       }
+      else if (nextIf.getElseBranch() == null && equivalence.expressionsAreEquivalent(
+        extract, factory.createExpressionFromText(BoolUtils.getNegatedExpressionText(nextCondition), nextCondition))) {
+        // skip duplicating else branch in cases like
+        // if(foo && bar) {1} else if (!foo) {2} =>
+        // if(foo) { if(bar) {1} } else {2}
+        elseBranch = nextIf.getThenBranch();
+        chainFinished = true;
+        break;
+      }
       else {
         if (!(nextCondition instanceof PsiPolyadicExpression)) break;
         PsiPolyadicExpression nextPolyadic = (PsiPolyadicExpression)nextCondition;
@@ -150,6 +163,9 @@ public class SplitConditionUtil {
     String thenString;
     if (elseChain.isEmpty()) {
       thenString = createIfString(leave, thenBranch, (String)null, tracker);
+      if (elseBranch != null) {
+        thenString = "{" + thenString + "}";
+      }
     }
     else {
       thenString = "{" + createIfString(leave, thenBranch, String.join("\nelse ", elseChain), tracker) + "\n}";

java/java-tests/testData/codeInsight/splitIfAction/afterCommentBeforeElse2.java

@@ -1,5 +1,5 @@
 class C {
-    void foo() {
+    void foo(boolean a, boolean b, boolean c) {
         if (a) {
             if (b) {
                 call();

java/java-tests/testData/codeInsight/splitIfAction/afterIncomplete2.java

@@ -0,0 +1,8 @@
+public class SplitCondition {
+  void test(int x) {
+      if (x > 0) {
+          if (x < 10) {
+          } else if (x > 0 && x > 50)
+      } else if (x > 0 && x > 50)
+  }
+}

java/java-tests/testData/codeInsight/splitIfAction/afterRedundantChainedCondition.java

@@ -0,0 +1,11 @@
+public class SplitCondition {
+  private static void appendString(String phrase) {
+      if (phrase != null) {
+          if (phrase.contains("abc")) {
+              System.out.println("abc!");
+          }
+      } else {
+          System.out.println("null");
+      }
+  }
+}

java/java-tests/testData/codeInsight/splitIfAction/beforeCommentBeforeElse2.java

@@ -1,5 +1,5 @@
 class C {
-    void foo() {
+    void foo(boolean a, boolean b, boolean c) {
         if (a &<caret>& b) {
             call();
         } // foo

java/java-tests/testData/codeInsight/splitIfAction/beforeIncomplete2.java

@@ -0,0 +1,6 @@
+public class SplitCondition {
+  void test(int x) {
+    if(x > 0 &<caret>& x < 10) {}
+    else if(x > 0 && x > 50)
+  }
+}

java/java-tests/testData/codeInsight/splitIfAction/beforeRedundantChainedCondition.java

@@ -0,0 +1,10 @@
+public class SplitCondition {
+  private static void appendString(String phrase) {
+    if (phrase != null &<caret>& phrase.contains("abc")) {
+      System.out.println("abc!");
+    }
+    else if (phrase == null) {
+      System.out.println("null");
+    }
+  }
+}

java/java-tests/testSrc/com/intellij/java/codeInsight/intention/SplitIfActionTest.java

@@ -76,13 +76,21 @@ public class SplitIfActionTest extends LightJavaCodeInsightTestCase {
   public void testWithoutSpaces() {
     doTest();
   }
-  
+
+  public void testRedundantChainedCondition() {
+    doTest();
+  }
+
   public void testIncomplete() {
     configureByFile("/codeInsight/splitIfAction/before" + getTestName(false) + ".java");
     SplitIfAction action = new SplitIfAction();
     assertFalse(action.isAvailable(getProject(), getEditor(), getFile()));
   }
 
+  public void testIncomplete2() {
+    doTest();
+  }
+
   private void doTest() {
     configureByFile("/codeInsight/splitIfAction/before" + getTestName(false)+ ".java");
     CommonCodeStyleSettings settings = CodeStyle.getSettings(getFile()).getCommonSettings(JavaLanguage.INSTANCE);