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Add a utility to resolve main methods from a java file (#222)
* Add an utility to resolve main methods from a java file Signed-off-by: Jinbo Wang <[email protected]> * Refactor the logic to search main method * Return DebugException instead of Exception * fix review comments * Rename codeLens to mainMethod info
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‎com.microsoft.java.debug.plugin/plugin.xml‎

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<command
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id="vscode.java.validateLaunchConfig">
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</command>
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<command
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id="vscode.java.resolveMainMethod">
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</command>
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</delegateCommandHandler>
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</extension>
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</plugin>

‎com.microsoft.java.debug.plugin/src/main/java/com/microsoft/java/debug/plugin/internal/JavaDebugDelegateCommandHandler.java‎

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public static String VALIDATE_LAUNCHCONFIG = "vscode.java.validateLaunchConfig";
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public static String RESOLVE_MAINMETHOD = "vscode.java.resolveMainMethod";
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@Override
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public Object executeCommand(String commandId, List<Object> arguments, IProgressMonitor progress) throws Exception {
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if (DEBUG_STARTSESSION.equals(commandId)) {
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return DebugSettingUtils.configDebugSettings(arguments);
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} else if (VALIDATE_LAUNCHCONFIG.equals(commandId)) {
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return new ResolveMainClassHandler().validateLaunchConfig(arguments);
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} else if (RESOLVE_MAINMETHOD.equals(commandId)) {
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return ResolveMainMethodHandler.resolveMainMethods(arguments);
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}
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throw new UnsupportedOperationException(String.format("Java debug plugin doesn't support the command '%s'.", commandId));

‎com.microsoft.java.debug.plugin/src/main/java/com/microsoft/java/debug/plugin/internal/ResolveMainMethodHandler.java‎

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/*******************************************************************************
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* Copyright (c) 2018 Microsoft Corporation and others.
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/legal/epl-v10.html
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*
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* Contributors:
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* Microsoft Corporation - initial API and implementation
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*******************************************************************************/
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package com.microsoft.java.debug.plugin.internal;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.List;
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import org.eclipse.core.resources.IProject;
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import org.eclipse.core.resources.IResource;
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import org.eclipse.jdt.core.Flags;
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import org.eclipse.jdt.core.ICompilationUnit;
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import org.eclipse.jdt.core.IJavaElement;
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import org.eclipse.jdt.core.IJavaProject;
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import org.eclipse.jdt.core.IMethod;
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import org.eclipse.jdt.core.ISourceRange;
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import org.eclipse.jdt.core.ISourceReference;
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import org.eclipse.jdt.core.IType;
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import org.eclipse.jdt.core.JavaModelException;
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import org.eclipse.jdt.ls.core.internal.JDTUtils;
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import org.eclipse.jdt.ls.core.internal.managers.ProjectsManager;
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import org.eclipse.lsp4j.Range;
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import com.microsoft.java.debug.core.DebugException;
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public class ResolveMainMethodHandler {
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/**
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* Resolve the main methods from the current file.
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* @return an array of main methods.
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*/
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public static Object resolveMainMethods(List<Object> arguments) throws DebugException {
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if (arguments == null || arguments.isEmpty()) {
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return Collections.emptyList();
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}
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String uri = (String) arguments.get(0);
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final ICompilationUnit unit = JDTUtils.resolveCompilationUnit(uri);
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if (unit == null || unit.getResource() == null || !unit.getResource().exists()) {
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return Collections.emptyList();
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}
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try {
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return resolveMainMethodCore(unit);
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} catch (Exception e) {
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throw new DebugException("Failed to resolve main method codeLens: " + e.getMessage(), e);
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}
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}
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private static List<MainMethod> resolveMainMethodCore(ICompilationUnit compilationUnit) throws JavaModelException {
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List<MainMethod> result = new ArrayList<>();
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for (IMethod method : searchMainMethods(compilationUnit)) {
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MainMethod mainMethod = extractMainMethodInfo(compilationUnit, method);
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if (mainMethod != null) {
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result.add(mainMethod);
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}
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}
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return result;
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}
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private static List<IMethod> searchMainMethods(ICompilationUnit compilationUnit) throws JavaModelException {
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List<IMethod> result = new ArrayList<>();
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for (IType type : getPotentialMainClassTypes(compilationUnit)) {
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IMethod method = getMainMethod(type);
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if (method != null) {
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result.add(method);
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}
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}
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return result;
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}
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private static IMethod getMainMethod(IType type) throws JavaModelException {
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for (IMethod method : type.getMethods()) {
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// Have at most one main method in the member methods of the type.
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if (method.isMainMethod()) {
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return method;
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}
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}
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return null;
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}
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private static List<IType> getPotentialMainClassTypes(ICompilationUnit compilationUnit) throws JavaModelException {
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List<IType> result = new ArrayList<>();
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IType[] topLevelTypes = compilationUnit.getTypes();
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result.addAll(Arrays.asList(topLevelTypes));
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for (IType type : topLevelTypes) {
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result.addAll(getPotentialMainClassTypesInChildren(type));
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}
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return result;
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}
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private static List<IType> getPotentialMainClassTypesInChildren(IType type) throws JavaModelException {
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IType[] children = type.getTypes();
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if (children.length == 0) {
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return Collections.emptyList();
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}
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List<IType> result = new ArrayList<>();
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for (IType child : children) {
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// main method can only exist in the static class or top level class.
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if (child.isClass() && Flags.isStatic(child.getFlags())) {
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result.add(child);
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result.addAll(getPotentialMainClassTypesInChildren(child));
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}
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}
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return result;
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}
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private static MainMethod extractMainMethodInfo(ICompilationUnit typeRoot, IMethod method) throws JavaModelException {
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final Range range = getRange(typeRoot, method);
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IResource resource = typeRoot.getResource();
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if (resource != null) {
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IProject project = resource.getProject();
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if (project != null) {
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String mainClass = method.getDeclaringType().getFullyQualifiedName();
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IJavaProject javaProject = JdtUtils.getJavaProject(project);
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if (javaProject != null) {
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String moduleName = JdtUtils.getModuleName(javaProject);
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if (moduleName != null) {
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mainClass = moduleName + "/" + mainClass;
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}
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}
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String projectName = ProjectsManager.DEFAULT_PROJECT_NAME.equals(project.getName()) ? null : project.getName();
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return new MainMethod(range, mainClass, projectName);
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}
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}
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return null;
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}
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private static Range getRange(ICompilationUnit typeRoot, IJavaElement element) throws JavaModelException {
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ISourceRange r = ((ISourceReference) element).getNameRange();
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return JDTUtils.toRange(typeRoot, r.getOffset(), r.getLength());
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}
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static class MainMethod {
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private Range range;
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private String mainClass;
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private String projectName;
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public MainMethod(Range range, String mainClass, String projectName) {
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this.range = range;
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this.mainClass = mainClass;
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this.projectName = projectName;
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}
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}
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}

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