org.sonar.java.checks.AbstractClassWithoutAbstractMethodCheck Maven / Gradle / Ivy

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/*
 * SonarQube Java
 * Copyright (C) 2012 SonarSource
 * [email protected]
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02
 */
package org.sonar.java.checks;

import com.google.common.collect.ImmutableList;
import org.sonar.api.server.rule.RulesDefinition;
import org.sonar.check.Priority;
import org.sonar.check.Rule;
import org.sonar.java.tag.Tag;
import org.sonar.plugins.java.api.IssuableSubscriptionVisitor;
import org.sonar.plugins.java.api.semantic.Symbol;
import org.sonar.plugins.java.api.tree.ClassTree;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.plugins.java.api.tree.TypeTree;
import org.sonar.squidbridge.annotations.SqaleConstantRemediation;
import org.sonar.squidbridge.annotations.SqaleSubCharacteristic;

import java.util.Collection;
import java.util.List;

@Rule(
  key = "S1694",
  name = "An abstract class should have both abstract and concrete methods",
  priority = Priority.MINOR,
  tags = {Tag.CONVENTION})
@SqaleSubCharacteristic(RulesDefinition.SubCharacteristics.UNDERSTANDABILITY)
@SqaleConstantRemediation("5min")
public class AbstractClassWithoutAbstractMethodCheck extends IssuableSubscriptionVisitor {

  @Override
  public List nodesToVisit() {
    return ImmutableList.of(Tree.Kind.CLASS);
  }

  @Override
  public void visitNode(Tree tree) {
    ClassTree classTree = (ClassTree) tree;
    Symbol.TypeSymbol typeSymbol = classTree.symbol();
    if (typeSymbol.isAbstract()) {
      Collection symbols = typeSymbol.memberSymbols();
      int abstractMethod = countAbstractMethods(symbols);
      if (isExtendingObject(classTree) && abstractMethod == symbols.size() - 2) {
        // emtpy abstract class or only abstract method
        context.addIssue(tree, this, "Convert this \"" + typeSymbol + "\" class to an interface");
      }
      if (symbols.size() > 2 && abstractMethod == 0 && !isPartialImplementation(classTree)) {
        // Not empty abstract class with no abstract method
        context.addIssue(tree, this, "Convert this \"" + typeSymbol + "\" class to a concrete class with a private constructor");
      }
    }
  }

  private static boolean isExtendingObject(ClassTree tree) {
    TypeTree superClass = tree.superClass();
    return superClass == null || superClass.symbolType().is("java.lang.Object");
  }

  private static boolean isPartialImplementation(ClassTree tree) {
    return tree.superClass() != null || !tree.superInterfaces().isEmpty();
  }

  private static int countAbstractMethods(Collection symbols) {
    int abstractMethod = 0;
    for (Symbol sym : symbols) {
      if (isAbstractMethod(sym)) {
        abstractMethod++;
      }
    }
    return abstractMethod;
  }

  private static boolean isAbstractMethod(Symbol sym) {
    return sym.isMethodSymbol() && sym.isAbstract();
  }
}