Introduce variable: support extraction form switch labels (IDEA-128795)

java/java-impl/src/com/intellij/refactoring/introduceVariable/IntroduceVariableBase.java

@@ -589,6 +589,12 @@ public abstract class IntroduceVariableBase extends IntroduceHandlerBase {
       }
     }
 
+    String enumInSwitchError = RefactoringUtil.checkEnumConstantInSwitchLabel(expr);
+    if (enumInSwitchError != null) {
+      showErrorMessage(project, editor, enumInSwitchError);
+      return false;
+    }
+
 
     final PsiType originalType = RefactoringUtil.getTypeByExpressionWithExpectedType(expr);
     if (originalType == null || LambdaUtil.notInferredType(originalType)) {
@@ -662,7 +668,7 @@ public abstract class IntroduceVariableBase extends IntroduceHandlerBase {
             getSettings(project, editor, expr, occurrences, typeSelectorManager, inFinalContext, hasWriteAccess, validator, chosenAnchor,
                         choice);
 
-          final boolean cantChangeFinalModifier = (hasWriteAccess || inFinalContext) && allChoice;
+          final boolean cantChangeFinalModifier = (hasWriteAccess && allChoice) || inFinalContext;
 
           PsiExpression[] allOccurrences = Arrays.stream(occurrences)
             .filter(occurrence -> allChoice || (noWriteChoice && !PsiUtil.isAccessedForWriting(occurrence)) || expr.equals(occurrence))

java/java-impl/src/com/intellij/refactoring/introduceVariable/VariableExtractor.java

@@ -254,6 +254,12 @@ class VariableExtractor {
         return firstOccurrence;
       }
     }
+    if (anchor instanceof PsiSwitchLabelStatement) {
+      PsiSwitchStatement statement = ((PsiSwitchLabelStatement)anchor).getEnclosingSwitchStatement();
+      if (statement != null) {
+        return statement;
+      }
+    }
     if (RefactoringUtil.isLoopOrIf(anchor.getParent())) return anchor;
     PsiElement child = locateAnchor(anchor);
     if (IntroduceVariableBase.isFinalVariableOnLHS(expr)) {

java/java-impl/src/com/intellij/refactoring/util/RefactoringUtil.java

@@ -46,9 +46,11 @@ import com.intellij.psi.search.SearchScope;
 import com.intellij.psi.search.searches.ReferencesSearch;
 import com.intellij.psi.util.*;
 import com.intellij.refactoring.PackageWrapper;
+import com.intellij.refactoring.RefactoringBundle;
 import com.intellij.refactoring.introduceField.ElementToWorkOn;
 import com.intellij.refactoring.introduceVariable.IntroduceVariableBase;
 import com.intellij.util.IncorrectOperationException;
+import com.intellij.util.ObjectUtils;
 import com.intellij.util.text.UniqueNameGenerator;
 import gnu.trove.THashMap;
 import org.jetbrains.annotations.Contract;
@@ -1024,6 +1026,16 @@ public class RefactoringUtil {
     return EnsureCodeBlockImpl.ensureCodeBlock(expression);
   }
 
+  public static String checkEnumConstantInSwitchLabel(PsiExpression expr) {
+    if (PsiUtil.skipParenthesizedExprUp(expr.getParent()) instanceof PsiSwitchLabelStatement) {
+      PsiReferenceExpression ref = ObjectUtils.tryCast(PsiUtil.skipParenthesizedExprDown(expr), PsiReferenceExpression.class);
+      if (ref != null && ref.resolve() instanceof PsiEnumConstant) {
+        return RefactoringBundle.getCannotRefactorMessage(RefactoringBundle.message("refactoring.introduce.variable.enum.in.label.message"));
+      }
+    }
+    return null;
+  }
+
   public interface ImplicitConstructorUsageVisitor {
     void visitConstructor(PsiMethod constructor, PsiMethod baseConstructor);
 

java/java-impl/src/com/intellij/refactoring/util/occurrences/BaseOccurrenceManager.java

@@ -15,9 +15,7 @@
  */
 package com.intellij.refactoring.util.occurrences;
 
-import com.intellij.psi.PsiClass;
-import com.intellij.psi.PsiElement;
-import com.intellij.psi.PsiExpression;
+import com.intellij.psi.*;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.refactoring.introduceField.ElementToWorkOn;
 import com.intellij.refactoring.util.RefactoringUtil;
@@ -87,11 +85,15 @@ public abstract class BaseOccurrenceManager implements OccurrenceManager {
     PsiElement scopeToDeclare = null;
     for (PsiExpression occurrence : occurrences) {
       final PsiElement data = occurrence.getUserData(ElementToWorkOn.PARENT);
+      PsiElement element = data != null ? data : occurrence;
       if (scopeToDeclare == null) {
-        scopeToDeclare = data != null ? data : occurrence;
+        scopeToDeclare = element;
       }
       else {
-        scopeToDeclare = PsiTreeUtil.findCommonParent(scopeToDeclare, data != null ? data : occurrence);
+        scopeToDeclare = PsiTreeUtil.findCommonParent(scopeToDeclare, element);
+      }
+      if (PsiTreeUtil.getParentOfType(element, PsiSwitchLabelStatement.class, true, PsiStatement.class) != null) {
+        return true;
       }
     }
     if(scopeToDeclare == null) {

java/java-tests/testData/refactoring/introduceVariable/CaseLabel.after.java

@@ -0,0 +1,14 @@
+class A {
+    private void A() {
+        final int temp = 2;
+        switch (1) {
+            case 1:
+                System.out.println(1);
+                break;
+            case temp:
+                System.out.println(temp);
+                break;
+        }
+
+    }
+}

java/java-tests/testData/refactoring/introduceVariable/CaseLabel.java

@@ -0,0 +1,13 @@
+class A {
+    private void A() {
+        switch (1) {
+            case 1:
+                System.out.println(1);
+                break;
+            case <selection>2</selection>:
+                System.out.println(2);
+                break;
+        }
+
+    }
+}

java/java-tests/testData/refactoring/introduceVariable/CaseLabelEnum.java

@@ -0,0 +1,14 @@
+class A {
+    private void A(X x) {
+        switch (x) {
+            case A:
+                System.out.println(1);
+                break;
+            case <selection>B</selection>:
+                System.out.println(2);
+                break;
+        }
+
+    }
+}
+enum X {A,B,C}

java/java-tests/testSrc/com/intellij/java/refactoring/IntroduceVariableTest.java

@@ -204,6 +204,21 @@ public class IntroduceVariableTest extends LightCodeInsightTestCase {
     doTest(new MockIntroduceVariableHandler("temp", true, false, false, "Node"));
   }
 
+  public void testCaseLabel() {
+    doTest(new MockIntroduceVariableHandler("temp", true, false, false, "int"));
+  }
+
+  public void testCaseLabelEnum() {
+    try {
+      doTest(new MockIntroduceVariableHandler("temp", true, false, false, ""));
+    }
+    catch (RuntimeException e) {
+      assertEquals("Error message:Cannot perform refactoring.\nEnum constant in switch label cannot be extracted", e.getMessage());
+      return;
+    }
+    fail("Should not be able to perform refactoring");
+  }
+
   public void testIfConditionAndChain() {
     doTest(new MockIntroduceVariableHandler("temp", true, false, false, CommonClassNames.JAVA_LANG_STRING));
   }

platform/platform-resources-en/src/messages/RefactoringBundle.properties

@@ -846,4 +846,6 @@ generate.module.descriptors.build.required.message=Couldn't generate module desc
 generate.module.descriptors.scanning.message=Scanning Compiler Output
 generate.module.descriptors.collecting.message=Collecting Dependencies
 generate.module.descriptors.analysing.message=Analysing Dependencies
-generate.module.descriptors.preparing.message=Preparing Code
+generate.module.descriptors.preparing.message=Preparing Code
+
+refactoring.introduce.variable.enum.in.label.message=Enum constant in switch label cannot be extracted