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Henshin Interpreter

The Henshin interpreter is the default engine for executing model transformations defined in Henshin. The interpreter can be invoked either using a wizard or programmatically.

Interpreter Wizard

Henshin Interpreter Wizard

The interpreter wizard can be invoked by a right-click on a *.henshin file in the Package Explorer and selecting Henshin→Apply with Henshin.

In the first page of the wizard, you need to enter the following information:

  • Choose a transformation rule or unit to be applied.
  • Specify a model file to be transformed using the rule or unit.
  • Enter possible parameters of the rule or unit. Make sure that the type of the parameters is correctly set. Ignore means that the parameter is not set and will be matched automatically by the interpreter.

If you click Preview you should either see the modifications to the model or get a message that the rule or unit could not be applied. If you think it should be applicable but still get a message that it is not, make sure the parameters are all correctly set including their types.

If you click Transform the model will be transformed and saved, if possible.

Interpreter API

The interpreter can be also invoked programatically, either as an IApplication in Eclipse or as a simple stand-alone Java app.

Make sure you have all dependencies fulfilled to the Henshin runtime and to EMF. Then you can invoke the interpreter as shown below. Particularly, you should include the model and the interpreter plug-in of Henshin. For examples, see also the Java source codes in the documented examples page.

Loading

For loading you can use HenshinResourceSet, which provides some convenience methods.

Transforming

import java.util.List;
 
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.henshin.interpreter.EmfEngine;
import org.eclipse.emf.henshin.interpreter.RuleApplication;
import org.eclipse.emf.henshin.interpreter.util.Match;
import org.eclipse.emf.henshin.matching.EmfGraph;
import org.eclipse.emf.henshin.model.Rule;
import org.eclipse.emf.henshin.model.TransformationSystem;
import org.eclipse.emf.henshin.model.resource.HenshinResourceSet;
 
/**
 * A benchmark constructing multiple levels of a Sierpinski triangle.
 * 
 * @see <a href="http://en.wikipedia.org/wiki/Sierpinski_triangle">Sierpinski Triangle</a>
 */
public class SierpinskiBenchmark {
 
  public static void main(String[] args) {
 
    // Create a resource set with a base directory:
    HenshinResourceSet resourceSet = 
            new HenshinResourceSet("src/org/eclipse/emf/henshin/examples/sierpinski/model");
 
    // Load the transformation system:
    TransformationSystem trasys = resourceSet.getTransformationSystem("sierpinski.henshin");
 
    // Load the first level of the Sierpinski triangle:
    EObject container = resourceSet.getFirstRoot("sierpinski-start.xmi");
 
    // Initialize the Henshin interpreter:
    EmfGraph graph = new EmfGraph(container);
    graph.removeEObject(container);
    EmfEngine engine = new EmfEngine(graph);
 
    // Load the rule:
    Rule addTriangleRule = trasys.findRuleByName("AddTriangle");
 
    System.out.println(Runtime.getRuntime().maxMemory() / (1024 * 1024) + "MB available memory\n");
 
    // Iteratively compute the Sierpinski triangle:
    int i = 1;
    while (true) {
 
	// Find all matches:
	long startTime = System.nanoTime();
	RuleApplication addTriangle = new RuleApplication(engine, addTriangleRule);
	List<Match> matches = addTriangle.findAllMatches();
	long matchingTime = (System.nanoTime() - startTime) / 1000000;
 
	System.out.println("Level: " + i);
	System.out.println("Rule applications:" + matches.size());
	System.out.println("Matching: " + matchingTime + "ms");
 
	// Apply rule with all matches:
	startTime = System.nanoTime();
	for (Match match : matches) {
	    addTriangle = new RuleApplication(engine, addTriangleRule);
	    addTriangle.setMatch(match);
	    addTriangle.apply();
	}
	long runtime = (System.nanoTime() - startTime) / 1000000;
 
	System.out.println("Application: " + runtime + "ms");
	System.out.println("Total: " + (matchingTime + runtime) + "ms");
	System.out.println("Nodes: " + graph.geteObjects().size());
	System.out.println();
	i++;
 
	}	
    }	
}

Saving

If something goes wrong, you can always use the Eclipse debugger to find out what's going on (see here for a tutorial).