org.sonar.java.checks.UselessIncrementCheck 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.model.SyntacticEquivalence;
import org.sonar.plugins.java.api.tree.AssignmentExpressionTree;
import org.sonar.plugins.java.api.tree.ExpressionTree;
import org.sonar.plugins.java.api.tree.ReturnStatementTree;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.plugins.java.api.tree.UnaryExpressionTree;
import org.sonar.squidbridge.annotations.ActivatedByDefault;
import org.sonar.squidbridge.annotations.SqaleConstantRemediation;
import org.sonar.squidbridge.annotations.SqaleSubCharacteristic;

import java.util.List;

@Rule(
  key = "S2123",
  name = "Values should not be uselessly incremented",
  tags = {"bug"},
  priority = Priority.CRITICAL)
@ActivatedByDefault
@SqaleSubCharacteristic(RulesDefinition.SubCharacteristics.LOGIC_RELIABILITY)
@SqaleConstantRemediation("5min")
public class UselessIncrementCheck extends SubscriptionBaseVisitor {

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

  @Override
  public void visitNode(Tree tree) {
    if (tree.is(Tree.Kind.RETURN_STATEMENT)) {
      ExpressionTree returnExpression = ((ReturnStatementTree) tree).expression();
      if (returnExpression != null && isPostfix(returnExpression)) {
        addIssue(returnExpression);
      }
    } else if (tree.is(Tree.Kind.ASSIGNMENT)) {
      AssignmentExpressionTree aet = (AssignmentExpressionTree) tree;
      if (isPostfix(aet.expression())) {
        UnaryExpressionTree postfix = (UnaryExpressionTree) aet.expression();
        if (SyntacticEquivalence.areEquivalent(aet.variable(), postfix.expression())) {
          addIssue(postfix);
        }
      }
    }
  }

  private void addIssue(ExpressionTree expression) {
    addIssue(expression, "Remove this increment or correct the code not to waste it.");
  }

  private boolean isPostfix(ExpressionTree tree) {
    return tree.is(Tree.Kind.POSTFIX_INCREMENT, Tree.Kind.POSTFIX_DECREMENT);
  }

}