auto pretty formatting in xtext - eclipse-plugin

Question

I want to ask that is there a way to do Pretty formatting in xtext automatically without (ctrl+shift+f) or turning it on from preference menu. What I actually want is whenever a user completes writing the code it is automatically pretty formatted (or on runtime) without (ctrl+shift+f).

Answer 1

There is a way for doing that which is called "AutoEdit". It's not exactly when the user completes writing but it's with every token. That's at least what I have done. You can for sure change that. I will give you an example that I implemented myself for my project. It basically capitalizes everykeyword as the user types (triggered by spaces and endlines).
It is a UI thing. So, In your UI project:
in MyDslUiModule.java you need to attach your AutoEdit custom made class do that like this:
public Class<? extends DefaultAutoEditStrategyProvider> bindDefaultAutoEditStrategyProvider()
{
return MyDslAutoEditStrategyProvider.class;
}
Our class will be called MyDslAutoEditStrategyProvider so, go ahead and create it in a MyDslAutoEditStrategyProvider.java file. Mine had this to do what i explained in the introduction:
import java.util.Set;
import org.eclipse.jface.text.DocumentCommand;
import org.eclipse.jface.text.IAutoEditStrategy;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.xtext.GrammarUtil;
import org.eclipse.xtext.IGrammarAccess;
import org.eclipse.xtext.ui.editor.autoedit.DefaultAutoEditStrategyProvider;
import org.eclipse.xtext.ui.editor.model.XtextDocument;
import com.google.inject.Inject;
import com.google.inject.Provider;
public class MyDslAutoEditStrategyProvider extends DefaultAutoEditStrategyProvider {
#Inject
Provider<IGrammarAccess> iGrammar;
private Set<String> KWDS;
#Override
protected void configure(IEditStrategyAcceptor acceptor) {
KWDS = GrammarUtil.getAllKeywords(iGrammar.get().getGrammar());
IAutoEditStrategy strategy = new IAutoEditStrategy()
{
#Override
public void customizeDocumentCommand(IDocument document, DocumentCommand command)
{
if ( command.text.length() == 0 || command.text.charAt(0) > ' ') return;
IRegion reg = ((XtextDocument) document).getLastDamage();
try {
String token = document.get(reg.getOffset(), reg.getLength());
String possibleKWD = token.toLowerCase();
if ( token.equals(possibleKWD.toUpperCase()) || !KWDS.contains(possibleKWD) ) return;
document.replace(reg.getOffset(), reg.getLength(), possibleKWD.toUpperCase());
}
catch (Exception e)
{
System.out.println("AutoEdit error.\n" + e.getMessage());
}
}
};
acceptor.accept(strategy, IDocument.DEFAULT_CONTENT_TYPE);
super.configure(acceptor);
}
}
I assume you saying "user completes writing" can be as "user saves file". If so here is how to trigger the formatter on save:
in MyDslUiModule.java:
public Class<? extends XtextDocumentProvider> bindXtextDocumentProvider()
{
return MyDslDocumentProvider.class;
}
Create the MyDslDocumentProvider class:
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.jface.text.IDocument;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.handlers.IHandlerService;
import org.eclipse.xtext.ui.editor.model.XtextDocumentProvider;
public class MyDslDocumentProvider extends XtextDocumentProvider
{
#Override
protected void doSaveDocument(IProgressMonitor monitor, Object element, IDocument document, boolean overwrite)
throws CoreException {
IHandlerService service = (IHandlerService) PlatformUI.getWorkbench().getService(IHandlerService.class);
try {
service.executeCommand("org.eclipse.xtext.ui.FormatAction", null);
} catch (Exception e)
{
e.printStackTrace();
}
super.doSaveDocument(monitor, element, document, overwrite);
}
}