plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/inheritance/StaticInheritanceInspection.java

/*
 * Copyright 2003-2007 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.inheritance;

import com.intellij.psi.PsiClass;
import com.intellij.psi.PsiJavaCodeReferenceElement;
import com.intellij.psi.PsiReferenceList;
import com.siyeh.InspectionGadgetsBundle;
import com.siyeh.ig.BaseInspection;
import com.siyeh.ig.BaseInspectionVisitor;
import com.siyeh.ig.InspectionGadgetsFix;
import org.jetbrains.annotations.NotNull;

import java.util.HashSet;
import java.util.Set;

public class StaticInheritanceInspection extends BaseInspection {

  @Override
  @NotNull
  public String getDisplayName() {
    return InspectionGadgetsBundle.message(
      "static.inheritance.display.name");
  }

  @Override
  @NotNull
  protected String buildErrorString(Object... infos) {
    return InspectionGadgetsBundle.message(
      "static.inheritance.problem.descriptor");
  }

  @NotNull
  @Override
  protected InspectionGadgetsFix[] buildFixes(Object... infos) {
    return new InspectionGadgetsFix[]{new StaticInheritanceFix(false), new StaticInheritanceFix(true)};
  }


  @Override
  public BaseInspectionVisitor buildVisitor() {
    return new StaticInheritanceVisitor();
  }

  private static class StaticInheritanceVisitor
    extends BaseInspectionVisitor {

    @Override
    public void visitClass(@NotNull PsiClass aClass) {
      // no call to super, so it doesn't drill down
      final PsiReferenceList implementsList = aClass.getImplementsList();
      if (implementsList == null) {
        return;
      }
      final PsiJavaCodeReferenceElement[] references =
        implementsList.getReferenceElements();
      for (final PsiJavaCodeReferenceElement reference : references) {
        final PsiClass iface = (PsiClass)reference.resolve();
        if (iface != null) {
          if (interfaceContainsOnlyConstants(iface, new HashSet<PsiClass>())) {
            registerError(reference);
          }
        }
      }
    }

    private static boolean interfaceContainsOnlyConstants(
      PsiClass iface, Set<PsiClass> visitedIntefaces) {
      if (!visitedIntefaces.add(iface)) {
        return true;
      }
      if (iface.getAllFields().length == 0) {
        // ignore it, it's either a true interface or just a marker
        return false;
      }
      if (iface.getMethods().length != 0) {
        return false;
      }
      final PsiClass[] parentInterfaces = iface.getInterfaces();
      for (final PsiClass parentInterface : parentInterfaces) {
        if (!interfaceContainsOnlyConstants(parentInterface,
                                            visitedIntefaces)) {
          return false;
        }
      }
      return true;
    }
  }
}