Eclipse Community Forums: TMF (Xtext) » Create a value converter

Help

Home

Home » Modeling » TMF (Xtext) » Create a value converter

Show: Today's Messages :: Show Polls :: Message Navigator

Create a value converter [message #1797485]

Wed, 31 October 2018 14:29

Nuno Burnay

Messages: 5
Registered: October 2018

Junior Member

I'm trying to create a converter for a terminal rule of my grammar:

terminal URI_TEMPLATE: '`' .* '`';

I created a conversion class for that purpose:

public class HeadRESTTerminalConverters extends DefaultTerminalConverters {
	
	@Inject
	private PrettyPrintUriTemplate prettyPrint;
	
	@ValueConverter(rule = "URI_TEMPLATE")
	public IValueConverter<Optional<UriTemplate>> URI_TEMPLATE() {
		return new AbstractNullSafeConverter<Optional<UriTemplate>>() {
			@Override
			protected Optional<UriTemplate> internalToValue(String string, INode node) {
				return new UriTemplateParser().parse(string);
			}
			@Override
			protected String internalToString(Optional<UriTemplate> value) {
				return "`" + prettyPrint.print(value.get()) + "`";
			}
		};
	}
}

And I added the class to the runtime module:

class HeadRESTRuntimeModule extends AbstractHeadRESTRuntimeModule {
	
	override Class<? extends IValueConverterService> bindIValueConverterService() {
         HeadRESTTerminalConverters
    }
    
}

However, when generated again the artifacts, the terminal rule stays with the standard type String. Am I missing something?

Thank you.

Report message to a moderator

Re: Create a value converter [message #1797566 is a reply to message #1797485]

Thu, 01 November 2018 19:18

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

you actually need a EDatatype (via imported metamodel) to map to a custom Java Class.
then you have to state that the rule produces that datatype in the grammar

import "......" as mymetamodel

terminal URI_TEMPLATE returns mymetamodel::MyDataType: '`' .* '`';

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

Report message to a moderator

Re: Create a value converter [message #1797588 is a reply to message #1797566]

Fri, 02 November 2018 11:39

Nuno Burnay

Messages: 5
Registered: October 2018

Junior Member

Thank you for the answer.

I understood the general idea, however I cannot understand what to put in the "....." part of the import in this case (I'm suppose that must be similar to the 'ecore' case).

Now I have a solution that works, using the ecore::EJavaObject and doing casts in the necessary places, but it seems that your solution is more elegant.

Report message to a moderator