[java-inspections] IDEA-311650 Improvements to conversion of if-else to switch that use guarded patterns

- check guards to reuse pattern variables

GitOrigin-RevId: f09354cfa0dd3f58f154de372b56bc100a461322

java/java-impl/src/com/siyeh/ig/migration/IfCanBeSwitchInspection.java

@@ -4,7 +4,10 @@ package com.siyeh.ig.migration;
 import com.intellij.codeInsight.Nullability;
 import com.intellij.codeInsight.daemon.impl.analysis.HighlightControlFlowUtil;
 import com.intellij.codeInsight.daemon.impl.analysis.HighlightingFeature;
-import com.intellij.codeInspection.*;
+import com.intellij.codeInspection.CommonQuickFixBundle;
+import com.intellij.codeInspection.EnhancedSwitchMigrationInspection;
+import com.intellij.codeInspection.LocalQuickFix;
+import com.intellij.codeInspection.ProblemHighlightType;
 import com.intellij.codeInspection.dataFlow.NullabilityUtil;
 import com.intellij.codeInspection.options.OptPane;
 import com.intellij.codeInspection.util.IntentionFamilyName;
@@ -32,10 +35,7 @@ import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.ArrayList;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
+import java.util.*;
 
 public class IfCanBeSwitchInspection extends BaseInspection {
 
@@ -133,12 +133,9 @@ public class IfCanBeSwitchInspection extends BaseInspection {
     PsiTypeElement type = targetInstanceOf.getCheckType();
     if (type == null) return;
 
-    List<PsiTypeCastExpression> relatedCastExpressions =
-      SyntaxTraverser.psiTraverser(ifStatement.getThenBranch())
-        .filter(PsiTypeCastExpression.class)
-        .filter(cast -> InstanceOfUtils.findPatternCandidate(cast) == targetInstanceOf)
-        .toList();
+    List<PsiTypeCastExpression> relatedCastExpressions = new ArrayList<>(getRelatesCastExpressions(ifStatement.getThenBranch(), targetInstanceOf));
 
+    processConditions(ifStatement, targetInstanceOf, relatedCastExpressions);
     PsiLocalVariable castedVariable = null;
     for (PsiTypeCastExpression castExpression : relatedCastExpressions) {
       castedVariable = findCastedLocalVariable(castExpression);
@@ -162,6 +159,39 @@ public class IfCanBeSwitchInspection extends BaseInspection {
     );
   }
 
+  private static void processConditions(PsiIfStatement ifStatement,
+                                        PsiInstanceOfExpression targetInstanceOf,
+                                        List<PsiTypeCastExpression> relatedCastExpressions) {
+    PsiElement current = targetInstanceOf;
+    while (true) {
+      PsiElement parent = current.getParent();
+      if (parent == null || parent == ifStatement) {
+        break;
+      }
+      if (!(parent instanceof PsiPolyadicExpression polyadicExpression) ||
+          polyadicExpression.getOperationTokenType() != JavaTokenType.ANDAND) {
+        break;
+      }
+      PsiExpression[] operands = polyadicExpression.getOperands();
+      int index = Arrays.asList(operands).indexOf(current);
+      if (index == -1 || index == operands.length - 1) {
+        break;
+      }
+      for (int i = index; i < operands.length; i++) {
+        relatedCastExpressions.addAll(getRelatesCastExpressions(operands[i], targetInstanceOf));
+      }
+      current = parent;
+    }
+  }
+
+  @NotNull
+  private static List<PsiTypeCastExpression> getRelatesCastExpressions(PsiElement expression, PsiInstanceOfExpression targetInstanceOf) {
+    return SyntaxTraverser.psiTraverser(expression)
+      .filter(PsiTypeCastExpression.class)
+      .filter(cast -> InstanceOfUtils.findPatternCandidate(cast) == targetInstanceOf)
+      .toList();
+  }
+
   private static @Nullable PsiLocalVariable findCastedLocalVariable(PsiTypeCastExpression castExpression) {
     PsiLocalVariable variable = PsiTreeUtil.getParentOfType(castExpression, PsiLocalVariable.class);
     if (variable == null) return null;

java/java-tests/testData/ig/com/siyeh/igfixes/migration/if_can_be_switch/WhenCast.after.java

@@ -0,0 +1,15 @@
+package com.siyeh.ipp.switchtoif.replace_if_with_switch;
+
+import java.math.BigDecimal;
+
+public class Test {
+  String getText(Object object) {
+    final String result = switch (object) {
+        case String s when (s.startsWith("PU") || s.startsWith("PU1")) -> s;
+        case Character c -> "Tuesday";
+        case null, default -> "Sunday";
+    };<caret>
+
+      return result;
+  }
+}

java/java-tests/testData/ig/com/siyeh/igfixes/migration/if_can_be_switch/WhenCast.java

@@ -0,0 +1,20 @@
+package com.siyeh.ipp.switchtoif.replace_if_with_switch;
+
+import java.math.BigDecimal;
+
+public class Test {
+  String getText(Object object) {
+    final String result;
+    i<caret>f (object instanceof String && (((String)object).startsWith("PU") || ((String)object).startsWith("PU1"))) {
+      result = (String)object;
+    }
+    else if (object instanceof Character) {
+      result = "Tuesday";
+    }
+    else {
+      result = "Sunday";
+    }
+
+    return result;
+  }
+}

java/java-tests/testSrc/com/siyeh/ig/fixes/migration/IfCanBePatternSwitchFixTest.java

@@ -49,4 +49,5 @@ public class IfCanBePatternSwitchFixTest extends IGQuickFixesTestCase {
   public void testLeakScope() { assertQuickfixNotAvailable(); }
   public void testNullCast() { doTest(); }
   public void testNotDoubleCall() { doTest(); }
+  public void testWhenCast() { doTest(); }
 }