[java-core] JavaPsiEnumUtil moved to codeserver.core

GitOrigin-RevId: c4f14fb79181cebe0ff87f5830b64228c0937e70

java/codeserver/core/src/com/intellij/java/codeserver/core/JavaPsiEnumUtil.java

@@ -0,0 +1,50 @@
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.java.codeserver.core;
+
+import com.intellij.openapi.projectRoots.JavaSdkVersion;
+import com.intellij.openapi.projectRoots.JavaVersionService;
+import com.intellij.psi.*;
+import com.intellij.psi.impl.PsiImplUtil;
+import com.intellij.psi.util.PsiUtil;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Utility methods related to Java enums
+ */
+public final class JavaPsiEnumUtil {
+  /**
+   * @param field field to check
+   * @param enumClass an enum class returned from {@link #getEnumClassForExpressionInInitializer(PsiExpression)}
+   * @return true if the given field cannot be referenced in constructors or instance initializers of the given enum class.
+   */
+  public static boolean isRestrictedStaticEnumField(@NotNull PsiField field, @NotNull PsiClass enumClass) {
+    if (!field.hasModifierProperty(PsiModifier.STATIC)) return false;
+    if (field.getContainingClass() != enumClass) return false;
+
+    if (!JavaVersionService.getInstance().isAtLeast(field, JavaSdkVersion.JDK_1_6)) {
+      PsiType type = field.getType();
+      if (type instanceof PsiClassType classType && classType.resolve() == enumClass) return false;
+    }
+
+    return !PsiUtil.isCompileTimeConstant(field);
+  }
+
+  /**
+   * @param expr expression to analyze
+   * @return enum class, whose non-constant static fields cannot be used at a given place,
+   * null if there's no such restriction 
+   */
+  public static @Nullable PsiClass getEnumClassForExpressionInInitializer(@NotNull PsiExpression expr) {
+    if (PsiImplUtil.getSwitchLabel(expr) != null) return null;
+    PsiMember constructorOrInitializer = PsiUtil.findEnclosingConstructorOrInitializer(expr);
+    if (constructorOrInitializer == null || constructorOrInitializer.hasModifierProperty(PsiModifier.STATIC)) return null;
+    PsiClass enumClass = constructorOrInitializer instanceof PsiEnumConstantInitializer initializer
+                         ? initializer
+                         : constructorOrInitializer.getContainingClass();
+    if (enumClass instanceof PsiEnumConstantInitializer) {
+      enumClass = enumClass.getSuperClass();
+    }
+    return enumClass != null && enumClass.isEnum() ? enumClass : null;
+  }
+}