How to run the Xtext .mydsl file?

Question

The question may seem obvious, but I'm just beginning with Xtext . So after creating the xtext project, and running the mydsl.xtext file.
it launches a new iteration of eclipse. I create a new .mydsl file in a new project. But I don't know what to do next! How do I run the .mydsl file?? How do i use my DSL ??
All Xtext tutorial stops after creating the DSL and don't show how to use it. I was following the 15 minutes Xtext tutorial
My code is the hello word code given by eclipse, nothing really special at this point.

Answer 1

if you want a java main to read the model and execute the generator you may have a look at this snippet

package org.eclipse.xtext.example.domainmodel;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.xtext.generator.GeneratorContext;
import org.eclipse.xtext.generator.GeneratorDelegate;
import org.eclipse.xtext.generator.IGeneratorContext;
import org.eclipse.xtext.generator.JavaIoFileSystemAccess;
import org.eclipse.xtext.util.CancelIndicator;
import org.eclipse.xtext.validation.CheckMode;
import org.eclipse.xtext.validation.IResourceValidator;
import org.eclipse.xtext.validation.Issue;

import com.google.common.collect.Lists;
import com.google.inject.Injector;

/**
 * @author dietrich - Initial contribution and API
 */
public class Main {

    public static void main(String[] args) {
        // TODO traverse directory
        List<String> files = Lists.newArrayList("model/a.dmodel", "model/b.dmodel");
        Injector injector = new DomainmodelStandaloneSetup().createInjectorAndDoEMFRegistration();
        ResourceSet rs = injector.getInstance(ResourceSet.class);
        ArrayList<Resource> resources = Lists.newArrayList();
        for (String file : files) {
            Resource r = rs.getResource(URI.createFileURI(file), true);
            resources.add(r);
        }

        IResourceValidator validator = injector.getInstance(IResourceValidator.class);
        for (Resource r : resources) {
            List<Issue> issues = validator.validate(r, CheckMode.ALL, CancelIndicator.NullImpl);
            for (Issue i : issues) {
                System.out.println(i);
            }
        }

        GeneratorDelegate generator = injector.getInstance(GeneratorDelegate.class);
        JavaIoFileSystemAccess fsa = injector.getInstance(JavaIoFileSystemAccess.class);
        fsa.setOutputPath("src-gen-code/");
        GeneratorContext context = new GeneratorContext();
        context.setCancelIndicator(CancelIndicator.NullImpl);

        for (Resource r : resources) {
            generator.generate(r, fsa, context);
        }
    }

}

Answer 2

When you save your . yourdsl file on the editor you temporarily opened, it will automatically build it. Once it builds successfully without errors, you will have a directory called src-gen inside your project, on your workspace. There you'll have the files your dsl just generated based on your yourdsl Generator.xtend

Answer 3

The result of an Xtext project is a Domain Specific Language designed by your own, that can be parsed, validated, linked and used for code generation inside an IDE (Eclipse or Intellij as far as I know) and headless.

Depending on the features you wish to have in your DSL, you have to alter and create different classes inside your XText project.

Usually the first steps include:

• Create your grammar ( .xtext file), to specify how your DSL should be parsed and look syntactically.
• Run the language generation for the grammar (right click on the .xtext file -> run as --> generate Xtext artifacts)
• Run another eclipse instance (run as --> Eclipse Application) to see your grammar in action. For that, create a new project and put a file with your DSL File ending inside the project. A dialog will ask you to add your DSLs Project nature to the project. Agree and try to edit the file. this file should behave as specified in your xtext grammar.