1 files changed, 126 insertions, 0 deletions
diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/memory/InnerClassReferenceVisitor.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/memory/InnerClassReferenceVisitor.java
new file mode 100644
index 000000000000..6f1f817a7735
--- /dev/null
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/memory/InnerClassReferenceVisitor.java
@@ -0,0 +1,126 @@
+/*
+ * Copyright 2003-2014 Dave Griffith, Bas Leijdekkers
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.siyeh.ig.memory;
+
+import com.intellij.psi.*;
+import com.intellij.psi.util.InheritanceUtil;
+import com.intellij.psi.util.PsiTreeUtil;
+import com.siyeh.ig.psiutils.ParenthesesUtils;
+import org.jetbrains.annotations.NotNull;
+
+class InnerClassReferenceVisitor extends JavaRecursiveElementVisitor {
+
+  private final PsiClass innerClass;
+  private boolean referencesStaticallyAccessible = true;
+
+  public InnerClassReferenceVisitor(@NotNull PsiClass innerClass) {
+    this.innerClass = innerClass;
+  }
+
+  public boolean canInnerClassBeStatic() {
+    final PsiClass superClass = innerClass.getSuperClass();
+    if (!isClassStaticallyAccessible(superClass)) {
+      return false;
+    }
+    return referencesStaticallyAccessible;
+  }
+
+  private boolean isClassStaticallyAccessible(PsiClass aClass) {
+    if (PsiTreeUtil.isAncestor(innerClass, aClass, false) || aClass.hasModifierProperty(PsiModifier.STATIC)) {
+      return true;
+    }
+    final PsiClass containingClass = aClass.getContainingClass();
+    return containingClass == null || InheritanceUtil.isInheritorOrSelf(innerClass, containingClass, true);
+  }
+
+  @Override
+  public void visitThisExpression(@NotNull PsiThisExpression expression) {
+    if (!referencesStaticallyAccessible) {
+      return;
+    }
+    super.visitThisExpression(expression);
+    if (hasContainingClassQualifier(expression)) {
+      referencesStaticallyAccessible = false;
+    }
+  }
+
+  @Override
+  public void visitSuperExpression(@NotNull PsiSuperExpression expression) {
+    if (!referencesStaticallyAccessible) {
+      return;
+    }
+    super.visitSuperExpression(expression);
+    if (hasContainingClassQualifier(expression)) {
+      referencesStaticallyAccessible = false;
+    }
+  }
+
+  private boolean hasContainingClassQualifier(PsiQualifiedExpression expression) {
+    final PsiJavaCodeReferenceElement qualifier = expression.getQualifier();
+    if (qualifier == null) {
+      return false;
+    }
+    return !innerClass.equals(qualifier.resolve());
+  }
+
+  @Override
+  public void visitReferenceExpression(PsiReferenceExpression expression) {
+    if (!referencesStaticallyAccessible) {
+      return;
+    }
+    super.visitReferenceExpression(expression);
+    final PsiExpression qualifierExpression = ParenthesesUtils.stripParentheses(expression.getQualifierExpression());
+    if (qualifierExpression != null) {
+      return;
+    }
+    final PsiElement target = expression.resolve();
+    if (target instanceof PsiLocalVariable || target instanceof PsiParameter) {
+      return;
+    }
+    if (target instanceof PsiMethod || target instanceof PsiField) {
+      final PsiMember member = (PsiMember)target;
+      if (member.hasModifierProperty(PsiModifier.STATIC) || PsiTreeUtil.isAncestor(innerClass, member, true)) {
+        return;
+      }
+      if (!member.hasModifierProperty(PsiModifier.PRIVATE)) {
+        final PsiClass containingClass = member.getContainingClass();
+        if (InheritanceUtil.isInheritorOrSelf(innerClass, containingClass, true)) {
+          return;
+        }
+      }
+      referencesStaticallyAccessible = false;
+    }
+  }
+
+  @Override
+  public void visitNewExpression(PsiNewExpression expression) {
+    if (!referencesStaticallyAccessible) {
+      return;
+    }
+    super.visitNewExpression(expression);
+    final PsiJavaCodeReferenceElement classReference = expression.getClassOrAnonymousClassReference();
+    if (classReference == null) {
+      return;
+    }
+    final PsiElement target = classReference.resolve();
+    if (!(target instanceof PsiClass)) {
+      return;
+    }
+    if (!isClassStaticallyAccessible((PsiClass)target)) {
+      referencesStaticallyAccessible = false;
+    }
+  }
+}