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Xtext Grammar - Exclusion of a specific Rule [message #1064689]

Thu, 20 June 2013 10:47

Eclipse User

So I have the following rules:

HtmlAcceptedElement:
	BinaryElements | Image | Link | Text
;

and

BinaryElements:
	Bold | Italic | Underline | Paragraph
;

now I want for Bold to do the following:

Bold:
	'b' (htmlaccelement+=HtmlAcceptedElement)+ '/b'
;

but I want to don't allow Bold rule to be inside this: (htmlaccelement+=HtmlAcceptedElement)+
is this possible? to say somehow HtmlAcceptedElement except Bold ?

Thanks in advance!
Best regards,

Re: Xtext Grammar - Exclusion of a specific Rule [message #1064691 is a reply to message #1064689]

Thu, 20 June 2013 10:49

Eclipse User

Re: Xtext Grammar - Exclusion of a specific Rule [message #1064692 is a reply to message #1064691]

Thu, 20 June 2013 10:52

Eclipse User

so is not an easier way? because then I have to do the same for italic and all others
and thanks for the quick answer!

Re: Xtext Grammar - Exclusion of a specific Rule [message #1064703 is a reply to message #1064692]

Thu, 20 June 2013 11:07

Eclipse User

Hat about a check?

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Re: Xtext Grammar - Exclusion of a specific Rule [message #1064715 is a reply to message #1064703]

Thu, 20 June 2013 12:07

Eclipse User

Sorry, I don't get what you mean. What check? Or if you suggest to check in the grammar, how exactly is done that ?

Re: Xtext Grammar - Exclusion of a specific Rule [message #1064722 is a reply to message #1064715]

Thu, 20 June 2013 12:29

Eclipse User

No i Mean to solve it with Semantic validaton (javavalidator) instead of solving it in grammar

Re: Xtext Grammar - Exclusion of a specific Rule [message #1064740 is a reply to message #1064722]

Thu, 20 June 2013 14:34

Eclipse User

yes i could do that, but then the suggestion (ctrl+space) will still show what I don't need (the Bold again)

Re: Xtext Grammar - Exclusion of a specific Rule [message #1064746 is a reply to message #1064740]

Thu, 20 June 2013 14:54

Eclipse User

Hi,

you could try to fix content assist but this might be even more work than introducing the additional rules as i suggested before.

Update: i dont know if there is a nice place to hook into content assist maybe
org.eclipse.xtext.ui.editor.contentassist.AbstractContentProposalProvider.createProposals(ContentAssistContext, ICompletionProposalAcceptor)
could serve as starting point.

[Updated on: Thu, 20 June 2013 15:00] by Moderator

Re: Xtext Grammar - Exclusion of a specific Rule [message #1064748 is a reply to message #1064746]

Thu, 20 June 2013 15:01

Eclipse User

Hi,
in the additional rules is a flaw imagine that you have the following use case: b i <<here>> /i /b or i b <<here>> /b /i
at <<here>> i can add again b (or i) and /b (or /i) that I don't want. This assuming what you proposed plus:

HtmlAcceptedElementSpezial returns HtmlAcceptedElement:
BinaryElementsSpezialItalic | Image | Link | Text
;
BinaryElementsSpezialItalic returns BinaryElements:
Bold | Underline | Paragraph
;


Italic:
'i' (htmlaccelement+=HtmlAcceptedElementSpezialItalic )+ '/i'
;

Thanks for all the effort!

Re: Xtext Grammar - Exclusion of a specific Rule [message #1064749 is a reply to message #1064748]

Thu, 20 June 2013 15:10

Eclipse User

Sorry i dont know any out of the box solutions for this usecase.
and you are right the rules might explode.
unfortunately ParserBasedContentAssistContextFactory does not seem to have nice hooks for filtering.
and i dont know how easy skipping elements works on later states. (org.eclipse.xtext.ui.editor.contentassist.AbstractContentProposalProvider.createProposals(ContentAssistContext, ICompletionProposalAcceptor))
or even later.

Re: Xtext Grammar - Exclusion of a specific Rule [message #1064796 is a reply to message #1064689]

Fri, 21 June 2013 03:30

Eclipse User

You could write a separate rule for elements that can appear inside a
'Bold'. I would not recommend this, as the user would get an error from
the parser (unexpected token) instead of a helpful message (e.g. 'bold
not allowed within bold'). So rather be generous in the grammar and
cover these constraints with validation rules.

Am 20.06.13 16:47, schrieb Edwin Tuzar:
> So I have the following rules:
>
> HtmlAcceptedElement:
> BinaryElements | Image | Link | Text
> ;
>
>
> and
>
> BinaryElements:
> Bold | Italic | Underline | Paragraph
> ;
>
> now I want for Bold to do the following:
>
> Bold:
> 'b' (htmlaccelement+=HtmlAcceptedElement)+ '/b'
> ;
>
> but I want to don't allow Bold rule to be inside this:
> (htmlaccelement+=HtmlAcceptedElement)+ is this possible? to say somehow
> HtmlAcceptedElement except Bold ?
> Thanks in advance!
> Best regards,

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