if (ast == null)
if (ast == null || fPresenter.isCanceled())
	public void reconciled(CompilationUnit ast, boolean forced, IProgressMonitor progressMonitor) {		// TODO: get timestamp from document when copying its content for parsing		Object timeStamp= fPresenter.getTimestamp();				if (ast == null)			return;				ASTNode[] subtrees= getAffectedSubtrees(ast);		if (subtrees.length == 0)			return;				startReconcilingPositions();				reconcilePositions(subtrees);				TextPresentation textPresentation= fPresenter.createPresentation(fAddedPositions, fRemovedPositions, timeStamp);				fPresenter.updatePresentation(textPresentation, fAddedPositions, fRemovedPositions, timeStamp);				stopReconcilingPositions();	}