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Sonar codemod to remove redundant variable creation expression (#253)
Remove redundant variable creation expression when it is only returned or thrown [Given examples of the file](https://sonarcloud.io/project/issues?fileUuids=AYvtrjqJLCzGLicz7AcH&resolved=false&types=CODE_SMELL&id=nahsra_WebGoat_10_23): [Immediately return this expression instead of assigning it to the temporary variable "localeResolver".](https://sonarcloud.io/project/issues?open=AYvtrj5QLCzGLicz7AqQ&id=nahsra_WebGoat_10_23) [Immediately throw this expression instead of assigning it to the temporary variable "myException".](https://sonarcloud.io/project/issues?open=AYw20oU9yE-xQ1mlDtlZ&id=nahsra_WebGoat_10_23) Sonar rule reference: https://rules.sonarsource.com/java/RSPEC-1488/
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‎core-codemods/src/main/java/io/codemodder/codemods/RemoveRedundantVariableCreationCodemod.java‎

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package io.codemodder.codemods;
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import com.github.javaparser.ast.CompilationUnit;
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import com.github.javaparser.ast.expr.*;
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import com.github.javaparser.ast.stmt.*;
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import io.codemodder.*;
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import io.codemodder.providers.sonar.ProvidedSonarScan;
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import io.codemodder.providers.sonar.RuleIssues;
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import io.codemodder.providers.sonar.SonarPluginJavaParserChanger;
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import io.codemodder.providers.sonar.api.Issue;
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import java.util.Optional;
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import javax.inject.Inject;
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/** A codemod to remove redundant variable creation */
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@Codemod(
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id = "sonar:java/remove-redundant-variable-creation-s1488",
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reviewGuidance = ReviewGuidance.MERGE_WITHOUT_REVIEW,
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executionPriority = CodemodExecutionPriority.HIGH)
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public final class RemoveRedundantVariableCreationCodemod
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extends SonarPluginJavaParserChanger<ObjectCreationExpr> {
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@Inject
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public RemoveRedundantVariableCreationCodemod(
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@ProvidedSonarScan(ruleId = "java:S1488") final RuleIssues issues) {
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super(issues, ObjectCreationExpr.class, RegionNodeMatcher.MATCHES_START);
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}
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@Override
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public boolean onIssueFound(
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final CodemodInvocationContext context,
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final CompilationUnit cu,
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final ObjectCreationExpr objectCreationExpr,
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final Issue issue) {
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// Get full block statement
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final Optional<BlockStmt> blockStmtOpt = objectCreationExpr.findAncestor(BlockStmt.class);
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if (blockStmtOpt.isPresent()) {
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final BlockStmt blockStmt = blockStmtOpt.get();
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// Retrieve return/throw statement to update its expression to given objectCreationExpr param
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final Optional<Statement> lastStmtOpt = blockStmt.getStatements().getLast();
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// Retrieve the redundant variable declaration expression that will be removed
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final Optional<ExpressionStmt> exprStmtOpt =
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objectCreationExpr.findAncestor(ExpressionStmt.class);
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if (lastStmtOpt.isPresent() && exprStmtOpt.isPresent()) {
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final Statement lastStmt = lastStmtOpt.get();
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if (lastStmt instanceof ReturnStmt returnStmt) {
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returnStmt.setExpression(objectCreationExpr);
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} else if (lastStmt instanceof ThrowStmt throwStmt) {
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throwStmt.setExpression(objectCreationExpr);
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} else {
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return false;
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}
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// Remove the redundant variable creation expression
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blockStmt.getStatements().remove(exprStmtOpt.get());
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return true;
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}
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}
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return false;
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}
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}

‎core-codemods/src/main/resources/io/codemodder/codemods/RemoveRedundantVariableCreationCodemod/description.md‎

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This change removes intermediate variables who are only created to be thrown or returned in the next statement. This makes the code more readable, which makes reviewing the code for issues easier.
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Our changes look something like this:
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```diff
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public LocaleResolver localeResolver() {
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- SessionLocaleResolver localeResolver = new SessionLocaleResolver();
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- return localeResolver;
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+ return new SessionLocaleResolver();
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}
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```
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```diff
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public void process() {
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- Exception ex = new Exception();
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- throw ex;
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+ throw new Exception();
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}
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```

‎core-codemods/src/main/resources/io/codemodder/codemods/RemoveRedundantVariableCreationCodemod/report.json‎

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{
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"summary" : "Remove redundant variable creation expression when it is only returned/thrown (Sonar).",
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"change" : "Remove redundant variable creation expression when it is only returned/thrown.",
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"references" : [
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"https://rules.sonarsource.com/java/RSPEC-1488/"
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]
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}

‎core-codemods/src/test/java/io/codemodder/codemods/RemoveRedundantVariableCreationCodemodTest.java‎

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package io.codemodder.codemods;
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import io.codemodder.testutils.CodemodTestMixin;
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import io.codemodder.testutils.Metadata;
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@Metadata(
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codemodType = RemoveRedundantVariableCreationCodemod.class,
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testResourceDir = "remove-redundant-variable-creation-s1488",
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renameTestFile = "src/main/java/org/owasp/webgoat/container/MvcConfiguration.java",
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dependencies = {})
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final class RemoveRedundantVariableCreationCodemodTest implements CodemodTestMixin {}

‎core-codemods/src/test/resources/remove-redundant-variable-creation-s1488/Test.java.after‎

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/**
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* ************************************************************************************************
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*
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* <p>
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*
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* <p>This file is part of WebGoat, an Open Web Application Security Project utility. For details,
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* please see http://www.owasp.org/
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*
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* <p>Copyright (c) 2002 - 2014 Bruce Mayhew
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*
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* <p>This program is free software; you can redistribute it and/or modify it under the terms of the
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* GNU General Public License as published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* <p>This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* <p>You should have received a copy of the GNU General Public License along with this program; if
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* not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*
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* <p>Getting Source ==============
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*
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* <p>Source for this application is maintained at https://github.com/WebGoat/WebGoat, a repository
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* for free software projects.
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*
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* @author WebGoat
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* @version $Id: $Id
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* @since October 28, 2003
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*/
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package org.owasp.webgoat.container;
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import java.io.IOException;
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import java.nio.charset.StandardCharsets;
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import java.util.Map;
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import java.util.Set;
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import lombok.RequiredArgsConstructor;
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import lombok.extern.slf4j.Slf4j;
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import org.owasp.webgoat.container.i18n.Language;
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import org.owasp.webgoat.container.i18n.Messages;
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import org.owasp.webgoat.container.i18n.PluginMessages;
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import org.owasp.webgoat.container.lessons.LessonScanner;
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import org.owasp.webgoat.container.session.LabelDebugger;
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import org.springframework.context.ApplicationContext;
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import org.springframework.context.annotation.Bean;
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import org.springframework.context.annotation.Configuration;
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import org.springframework.core.io.ResourceLoader;
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import org.springframework.core.io.support.ResourcePatternResolver;
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import org.springframework.web.servlet.LocaleResolver;
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import org.springframework.web.servlet.ViewResolver;
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import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
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import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
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import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
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import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
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import org.springframework.web.servlet.i18n.LocaleChangeInterceptor;
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import org.springframework.web.servlet.i18n.SessionLocaleResolver;
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import org.thymeleaf.IEngineConfiguration;
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import org.thymeleaf.extras.springsecurity6.dialect.SpringSecurityDialect;
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import org.thymeleaf.spring6.SpringTemplateEngine;
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import org.thymeleaf.spring6.templateresolver.SpringResourceTemplateResolver;
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import org.thymeleaf.spring6.view.ThymeleafViewResolver;
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import org.thymeleaf.templatemode.TemplateMode;
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import org.thymeleaf.templateresolver.FileTemplateResolver;
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import org.thymeleaf.templateresolver.ITemplateResolver;
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import org.thymeleaf.templateresource.ITemplateResource;
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import org.thymeleaf.templateresource.StringTemplateResource;
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/** Configuration for Spring MVC */
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@Configuration
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@RequiredArgsConstructor
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@Slf4j
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public class MvcConfiguration implements WebMvcConfigurer {
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private static final String UTF8 = "UTF-8";
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private final LessonScanner lessonScanner;
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@Override
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public void addViewControllers(ViewControllerRegistry registry) {
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registry.addViewController("/login").setViewName("login");
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registry.addViewController("/lesson_content").setViewName("lesson_content");
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registry.addViewController("/start.mvc").setViewName("main_new");
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registry.addViewController("/scoreboard").setViewName("scoreboard");
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}
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@Bean
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public ViewResolver viewResolver(SpringTemplateEngine thymeleafTemplateEngine) {
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ThymeleafViewResolver resolver = new ThymeleafViewResolver();
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resolver.setTemplateEngine(thymeleafTemplateEngine);
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resolver.setCharacterEncoding(StandardCharsets.UTF_8.displayName());
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return resolver;
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}
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/**
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* Responsible for loading lesson templates based on Thymeleaf, for example:
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*
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* <p><div th:include="/lessons/spoofcookie/templates/spoofcookieform.html" id="content"></div>
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*/
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@Bean
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public ITemplateResolver lessonThymeleafTemplateResolver(ResourceLoader resourceLoader) {
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var resolver =
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new FileTemplateResolver() {
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@Override
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protected ITemplateResource computeTemplateResource(
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IEngineConfiguration configuration,
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String ownerTemplate,
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String template,
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String resourceName,
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String characterEncoding,
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Map<String, Object> templateResolutionAttributes) {
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try (var is =
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resourceLoader.getResource("classpath:" + resourceName).getInputStream()) {
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return new StringTemplateResource(
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new String(is.readAllBytes(), StandardCharsets.UTF_8));
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} catch (IOException e) {
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return null;
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}
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}
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};
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resolver.setOrder(1);
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return resolver;
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}
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/** Loads all normal WebGoat specific Thymeleaf templates */
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@Bean
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public ITemplateResolver springThymeleafTemplateResolver(ApplicationContext applicationContext) {
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SpringResourceTemplateResolver resolver = new SpringResourceTemplateResolver();
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resolver.setPrefix("classpath:/webgoat/templates/");
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resolver.setSuffix(".html");
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resolver.setTemplateMode(TemplateMode.HTML);
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resolver.setOrder(2);
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resolver.setCharacterEncoding(UTF8);
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resolver.setApplicationContext(applicationContext);
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return resolver;
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}
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/** Loads the html for the complete lesson, see lesson_content.html */
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@Bean
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public LessonTemplateResolver lessonTemplateResolver(ResourceLoader resourceLoader) {
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LessonTemplateResolver resolver = new LessonTemplateResolver(resourceLoader);
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resolver.setOrder(0);
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resolver.setCacheable(false);
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resolver.setCharacterEncoding(UTF8);
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return resolver;
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}
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/** Loads the lesson asciidoc. */
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@Bean
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public AsciiDoctorTemplateResolver asciiDoctorTemplateResolver(
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Language language, ResourceLoader resourceLoader) {
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log.debug("template locale {}", language);
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AsciiDoctorTemplateResolver resolver =
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new AsciiDoctorTemplateResolver(language, resourceLoader);
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resolver.setCacheable(false);
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resolver.setOrder(1);
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resolver.setCharacterEncoding(UTF8);
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return resolver;
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}
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@Bean
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public SpringTemplateEngine thymeleafTemplateEngine(
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ITemplateResolver springThymeleafTemplateResolver,
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LessonTemplateResolver lessonTemplateResolver,
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AsciiDoctorTemplateResolver asciiDoctorTemplateResolver,
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ITemplateResolver lessonThymeleafTemplateResolver) {
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SpringTemplateEngine engine = new SpringTemplateEngine();
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engine.setEnableSpringELCompiler(true);
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engine.addDialect(new SpringSecurityDialect());
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engine.setTemplateResolvers(
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Set.of(
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lessonTemplateResolver,
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asciiDoctorTemplateResolver,
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lessonThymeleafTemplateResolver,
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springThymeleafTemplateResolver));
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return engine;
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}
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@Override
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public void addResourceHandlers(ResourceHandlerRegistry registry) {
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// WebGoat internal
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registry.addResourceHandler("/css/**").addResourceLocations("classpath:/webgoat/static/css/");
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registry.addResourceHandler("/js/**").addResourceLocations("classpath:/webgoat/static/js/");
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registry
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.addResourceHandler("/plugins/**")
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.addResourceLocations("classpath:/webgoat/static/plugins/");
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registry
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.addResourceHandler("/fonts/**")
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.addResourceLocations("classpath:/webgoat/static/fonts/");
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// WebGoat lessons
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registry
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.addResourceHandler("/images/**")
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.addResourceLocations(
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lessonScanner.applyPattern("classpath:/lessons/%s/images/").toArray(String[]::new));
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registry
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.addResourceHandler("/lesson_js/**")
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.addResourceLocations(
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lessonScanner.applyPattern("classpath:/lessons/%s/js/").toArray(String[]::new));
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registry
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.addResourceHandler("/lesson_css/**")
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.addResourceLocations(
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lessonScanner.applyPattern("classpath:/lessons/%s/css/").toArray(String[]::new));
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registry
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.addResourceHandler("/lesson_templates/**")
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.addResourceLocations(
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lessonScanner.applyPattern("classpath:/lessons/%s/templates/").toArray(String[]::new));
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registry
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.addResourceHandler("/video/**")
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.addResourceLocations(
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lessonScanner.applyPattern("classpath:/lessons/%s/video/").toArray(String[]::new));
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}
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@Bean
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public PluginMessages pluginMessages(
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Messages messages, Language language, ResourcePatternResolver resourcePatternResolver) {
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PluginMessages pluginMessages = new PluginMessages(messages, language, resourcePatternResolver);
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pluginMessages.setDefaultEncoding("UTF-8");
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pluginMessages.setBasenames("i18n/WebGoatLabels");
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pluginMessages.setFallbackToSystemLocale(false);
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return pluginMessages;
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}
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@Bean
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public Language language(LocaleResolver localeResolver) {
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return new Language(localeResolver);
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}
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@Bean
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public LocaleResolver localeResolver() {
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return new SessionLocaleResolver();
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}
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public void doSomething() {
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throw new RuntimeException();
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}
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@Bean
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public LocaleChangeInterceptor localeChangeInterceptor() {
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LocaleChangeInterceptor lci = new LocaleChangeInterceptor();
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lci.setParamName("lang");
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return lci;
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}
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@Override
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public void addInterceptors(InterceptorRegistry registry) {
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registry.addInterceptor(localeChangeInterceptor());
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}
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@Bean
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public Messages messageSource(Language language) {
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Messages messages = new Messages(language);
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messages.setDefaultEncoding("UTF-8");
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messages.setBasename("classpath:i18n/messages");
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messages.setFallbackToSystemLocale(false);
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return messages;
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}
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@Bean
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public LabelDebugger labelDebugger() {
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return new LabelDebugger();
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}
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}

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