org.sonar.java.checks.SwitchCaseWithoutBreakCheck.java Source code

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Here is the source code for org.sonar.java.checks.SwitchCaseWithoutBreakCheck.java

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/*
 * SonarQube Java
 * Copyright (C) 2012-2017 SonarSource SA
 * mailto:info AT sonarsource DOT com
 *
 * 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  02110-1301, USA.
 */
package org.sonar.java.checks;

import com.google.common.collect.Lists;

import org.sonar.check.Rule;
import org.sonar.plugins.java.api.JavaFileScanner;
import org.sonar.plugins.java.api.JavaFileScannerContext;
import org.sonar.plugins.java.api.tree.BaseTreeVisitor;
import org.sonar.plugins.java.api.tree.BlockTree;
import org.sonar.plugins.java.api.tree.CaseLabelTree;
import org.sonar.plugins.java.api.tree.IfStatementTree;
import org.sonar.plugins.java.api.tree.StatementTree;
import org.sonar.plugins.java.api.tree.SwitchStatementTree;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.plugins.java.api.tree.TryStatementTree;

@Rule(key = "S128")
public class SwitchCaseWithoutBreakCheck extends BaseTreeVisitor implements JavaFileScanner {

    private JavaFileScannerContext context;

    @Override
    public void scanFile(JavaFileScannerContext context) {
        this.context = context;
        scan(context.getTree());
    }

    @Override
    public void visitSwitchStatement(SwitchStatementTree switchStatement) {
        switchStatement.cases().stream()
                // Exclude the last case as stated in RSPEC. This also excludes switches with no or a single case group.
                .limit(Math.max(0, switchStatement.cases().size() - 1)).forEach(caseGroup -> {
                    // Assign issues to the last label in the group
                    CaseLabelTree caseLabel = caseGroup.labels().get(caseGroup.labels().size() - 1);

                    // Reverse the body as commonly the unconditional exit will be at the end of the body.
                    if (Lists.reverse(caseGroup.body()).stream()
                            .noneMatch(SwitchCaseWithoutBreakCheck::isUnconditionalExit)) {
                        context.reportIssue(this, caseLabel,
                                "End this switch case with an unconditional break, return or throw statement.");
                    }
                });

        super.visitSwitchStatement(switchStatement);
    }

    private static boolean isUnconditionalExit(Tree syntaxNode) {
        switch (syntaxNode.kind()) {
        case BREAK_STATEMENT:
        case THROW_STATEMENT:
        case RETURN_STATEMENT:
        case CONTINUE_STATEMENT:
            return true;
        case BLOCK:
            return ((BlockTree) syntaxNode).body().stream()
                    .anyMatch(SwitchCaseWithoutBreakCheck::isUnconditionalExit);
        case TRY_STATEMENT:
            return isUnconditionalExitInTryCatchStatement((TryStatementTree) syntaxNode);
        case IF_STATEMENT:
            return isUnconditionalExitInIfStatement((IfStatementTree) syntaxNode);
        default:
            return false;
        }
    }

    private static boolean isUnconditionalExitInTryCatchStatement(TryStatementTree tryStatement) {
        return isUnconditionalExit(tryStatement.block())
                && tryStatement.catches().stream().allMatch(catchTree -> isUnconditionalExit(catchTree.block()));
    }

    private static boolean isUnconditionalExitInIfStatement(IfStatementTree ifStatement) {
        if (!isUnconditionalExit(ifStatement.thenStatement())) {
            return false;
        }

        StatementTree elseStatement = ifStatement.elseStatement();
        if (elseStatement == null) {
            // Without else this is a conditional exit.
            return false;
        }

        return isUnconditionalExit(elseStatement);
    }
}