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Xtext 2.4.2: What is CancelationIndicator ? [message #1075745]

Tue, 30 July 2013 01:29

J A

Messages: 31
Registered: July 2013

Member

Dear all,

While reading the code of of a validator, I hit the CancelIndicator, and don't understand what is its purpose and how to see its effect.

Can someone provide me with a hint ?

// Initializing code, inside org.eclipse.xtext.validation.NamesAreUniqueValidator{}

Map context = AbstractDeclarativeValidator.getContext();
CancelIndicator cancelIndicator = (CancelIndicator) context.get(CancelableDiagnostician.CANCEL_INDICATOR);
...

// Client code
org.eclipse.xtext.validation.NamesAreUniqueValidationHelper{

	public void checkUniqueNames(Iterable<IEObjectDescription> descriptions, CancelIndicator cancelIndicator, ValidationMessageAcceptor acceptor)
	{
		Iterator iter = descriptions.iterator();
		if (!(iter.hasNext()))
			return;
		Map clusterToNames = Maps.newHashMap();
		while (iter.hasNext())
		{
			IEObjectDescription description = (IEObjectDescription) iter.next();
			checkDescriptionForDuplicatedName(description, clusterToNames, acceptor);
			if ((cancelIndicator != null) && (cancelIndicator.isCanceled()))
				return;
		}
	}

}

[Updated on: Tue, 30 July 2013 01:30]

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Re: Xtext 2.4.2: What is CancelationIndicator ? [message #1075763 is a reply to message #1075745]

Tue, 30 July 2013 02:30

Henrik Lindberg

Messages: 2509
Registered: July 2009

Senior Member

It is used to periodically check if the user (or the system) has
cancelled an operation running in the background.

Look at the source of:

org.eclipse.xtext.util.CancelIndicator

where there is a null implementation (i.e. one that always reports that
operation should not be cancelled).

Hope that helps.

- henrik

On 2013-30-07 3:29, J A wrote:
> Dear all,
>
> While reading the code of of a validator, I hit the CancelIndicator, and
> don't understand what is its purpose and how to see its effect.
>
> Can someone provide me with a hint ?
>
>
> // Initializing code, inside
> org.eclipse.xtext.validation.NamesAreUniqueValidator{}
>
> Map context = AbstractDeclarativeValidator.getContext();
> CancelIndicator cancelIndicator = (CancelIndicator)
> context.get(CancelableDiagnostician.CANCEL_INDICATOR);
> ...
>
> // Client code
> org.eclipse.xtext.validation.NamesAreUniqueValidationHelper{
>
> public void checkUniqueNames(Iterable<IEObjectDescription>
> descriptions, CancelIndicator cancelIndicator, ValidationMessageAcceptor
> acceptor)
> {
> Iterator iter = descriptions.iterator();
> if (!(iter.hasNext()))
> return;
> Map clusterToNames = Maps.newHashMap();
> while (iter.hasNext())
> {
> IEObjectDescription description = (IEObjectDescription)
> iter.next();
> checkDescriptionForDuplicatedName(description,
> clusterToNames, acceptor);
> if ((cancelIndicator != null) &&
> (cancelIndicator.isCanceled()))
> return;
> }
> }
>
> }
>

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