The hint form Christian Dietrich pointed me in the right direction. Below is the code that I ended up with.
I have created a new class MyOutputConfigurationProvider that implements IOutputConfigurationProvider. The getOutputConfigurations method returns two output configurations, the default src-gen and a custom src-gen-once with the correct settings for generating sources only once.
package com.my.dsl;
import static com.google.common.collect.Sets.newHashSet;
import java.util.Set;
import org.eclipse.xtext.generator.IFileSystemAccess;
import org.eclipse.xtext.generator.IOutputConfigurationProvider;
import org.eclipse.xtext.generator.OutputConfiguration;
public class MyOutputConfigurationProvider implements
IOutputConfigurationProvider {
public final static String DEFAULT_OUTPUT_ONCE = "DEFAULT_OUTPUT_ONCE";
/**
* @return a set of {@link OutputConfiguration} available for the generator
*/
public Set<OutputConfiguration> getOutputConfigurations() {
OutputConfiguration defaultOutput = new OutputConfiguration(IFileSystemAccess.DEFAULT_OUTPUT);
defaultOutput.setDescription("Output Folder");
defaultOutput.setOutputDirectory("./src-gen");
defaultOutput.setOverrideExistingResources(true);
defaultOutput.setCreateOutputDirectory(true);
defaultOutput.setCleanUpDerivedResources(true);
defaultOutput.setSetDerivedProperty(true);
OutputConfiguration onceOutput = new OutputConfiguration(DEFAULT_OUTPUT_ONCE);
onceOutput.setDescription("Output Folder (once)");
onceOutput.setOutputDirectory("./src-gen-once");
onceOutput.setOverrideExistingResources(false);
onceOutput.setCreateOutputDirectory(true);
onceOutput.setCleanUpDerivedResources(false);
onceOutput.setSetDerivedProperty(true);
return newHashSet(defaultOutput, onceOutput);
}
}
To use the MyOutputConfigurationProvider implementation add a configure method to your module class:
/**
* Use this class to register components to be used within the IDE.
*/
public class MyDslUiModule extends com.my.dsl.ui.AbstractMyDslUiModule {
public MyDslUiModule(AbstractUIPlugin plugin) {
super(plugin);
}
@Override
public void configure(Binder binder) {
super.configure(binder);
binder.bind(IOutputConfigurationProvider.class).to(MyOutputConfigurationProvider.class).in(Singleton.class);
}
}