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Parsing inmemory text using Xtext outside of Eclipse [message #1765725]

Tue, 13 June 2017 21:14

Santhosh Kumar

Messages: 44
Registered: March 2011

Member

Thank you for this example which shows how to load a full file [0].

However, we have a requirement to parse a inmemory text not stored in the file (for ex., use enters DSL in a webform, which we need to parse and validate). How do I go about parsing arbitrary text?

[0] https://wiki.eclipse.org/Xtext/FAQ#How_do_I_load_my_model_in_a_standalone_Java_application.C2.A0.3F

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Re: Parsing inmemory text using Xtext outside of Eclipse [message #1765727 is a reply to message #1765725]

Tue, 13 June 2017 21:51

Santhosh Kumar

Messages: 44
Registered: March 2011

Member

After some research, got this below snippet working fine. Is this correct?

	public static MyDslModel createModel(String dslText) {
		Injector injector = new MyDslStandaloneSetup().createInjectorAndDoEMFRegistration();
		XtextResourceSet resourceSet = injector.getInstance(XtextResourceSet.class);
		resourceSet.addLoadOption(XtextResource.OPTION_RESOLVE_ALL, Boolean.TRUE);
		Resource resource = resourceSet.createResource(URI.createURI("test.mydsl")); 
		try {
			resource.load(new ByteArrayInputStream(dslText.getBytes("UTF-8")), new HashMap<>());
		} catch (IOException e) {
			throw new RuntimeException(e);
		}
		MyDslModel model = (MyDslModel) resource.getContents().get(0);
		
		return model;
	}

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Re: Parsing inmemory text using Xtext outside of Eclipse [message #1765870 is a reply to message #1765725]

Wed, 14 June 2017 06:28

Karsten Thoms

Messages: 762
Registered: July 2009
Location: Dortmund, Germany

Senior Member

I think you should better use resourceSet.getResource() instead of create/load.
Besides that it looks OK.

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Re: Parsing inmemory text using Xtext outside of Eclipse [message #1766226 is a reply to message #1765870]

Sun, 18 June 2017 22:18

Santhosh Kumar

Messages: 44
Registered: March 2011

Member

@karsten, I tried to do

Resource resource = resourceSet.getResource(URI.createURI("test.mydsl"), true);

but errors out saying file not found. It is resolving the test.mydsl against workspace. Since that file not really exists and we are trying to load inmemory text, not sure if that will work out with that call.

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Re: Parsing inmemory text using Xtext outside of Eclipse [message #1766228 is a reply to message #1766226]

Sun, 18 June 2017 23:57

Santhosh Kumar

Messages: 44
Registered: March 2011

Member

resourceSet.createResource started failing for second time we create same time. Not having complete knowledge about how EMF resource works, I adopted this version of utils which deletes the resource after parsing. Hope this is fine. Any feedback is appreciated.

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.HashMap;

import org.eclipse.emf.common.util.EList;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.xtext.resource.XtextResource;
import org.eclipse.xtext.resource.XtextResourceSet;

import com.MyDsl.MyDslStandaloneSetup;
import com.MyDsl.MyDsl.MyDslModel;
import com.google.inject.Injector;

public class MyDslUtils {
	private static final XtextResourceSet resourceSet;

	static {
		Injector injector = new MyDslStandaloneSetup().createInjectorAndDoEMFRegistration();
		resourceSet = injector.getInstance(XtextResourceSet.class);
		resourceSet.addLoadOption(XtextResource.OPTION_RESOLVE_ALL, Boolean.TRUE);
	}

	public static MyDslVisitor parse(String dslText) {

		URI uri = URI.createURI("temp-" + Math.abs(Math.random()) + ".mydsl");
		Resource resource = resourceSet.getResources().stream().filter(res -> res.getURI().toFileString().equals(uri.toFileString())).findFirst()
				.orElseGet(() -> resourceSet.createResource(uri));

		try {
			resource.unload();
			resource.load(new ByteArrayInputStream(dslText.getBytes("UTF-8")), new HashMap<>());
			EList<EObject> contents = resource.getContents();
			if (contents.isEmpty()) {
				return null;
			}

			MyDslModel model = (MyDslModel) contents.get(0);

			return new MyDslVisitor(model);

		} catch (IOException e) {
			throw new RuntimeException(e);
		} finally {
			try {
				resource.delete(new HashMap<>());
			} catch (IOException e) {
			}
		}

	}

	public static void main(String[] args) {
		MyDslVisitor visitor = MyDslUtils.parse("load into account");
	}
}

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