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Vanishing whitespaces due to optional keyword [message #643586]

Tue, 07 December 2010 15:05

Ulf Rueegg

Messages: 26
Registered: February 2010

Junior Member

Hi guys,

I'm currently facing a rather strange behaviour which I cannot explain.

Consider the following grammar:

grammar org.xtext.example.mydsl.MyDsl with org.eclipse.xtext.common.Terminals

generate myDsl "http://www.xtext.org/example/mydsl/MyDsl"

Module:
	"module" name=ID ":" body=ModuleBody "end" "module";
	
ModuleBody:
	name=ID ';'?
;

and this input:

module m1:
foo;
end module

Parsing works fine and as expected, but calling save on the resource results in the following

module m1:
fooend module

The semicolon is not there anymore as it is optional and the serializer cannot know if it was set before or not - so it's omitted. But why is there no whitespace between 'foo' and 'end'?

best regards

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Re: Vanishing whitespaces due to optional keyword [message #643668 is a reply to message #643586]

Tue, 07 December 2010 18:48

Sebastian Zarnekow

Messages: 3118
Registered: July 2009

Senior Member

Hi Ulf,

you'll have to tell your formatter that the whitespace between both
tokens is mandatory.

Regards,
Sebastian
--
Need professional support for Eclipse Modeling?
Go visit: http://xtext.itemis.com

Am 07.12.10 16:05, schrieb Ulf:
> Hi guys,
>
> I'm currently facing a rather strange behaviour which I cannot explain.
>
> Consider the following grammar:
>
>
> grammar org.xtext.example.mydsl.MyDsl with
> org.eclipse.xtext.common.Terminals
>
> generate myDsl "http://www.xtext.org/example/mydsl/MyDsl"
>
> Module:
> "module" name=ID ":" body=ModuleBody "end" "module";
>
> ModuleBody:
> name=ID ';'?
> ;
>
>
> and this input:
>
> module m1:
> foo;
> end module
>
>
> Parsing works fine and as expected, but calling save on the resource
> results in the following
>
> module m1:
> fooend module
>
>
> The semicolon is not there anymore as it is optional and the serializer
> cannot know if it was set before or not - so it's omitted. But why is
> there no whitespace between 'foo' and 'end'?
>
> best regards
>

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Re: Vanishing whitespaces due to optional keyword [message #643679 is a reply to message #643586]

Tue, 07 December 2010 20:01

Ulf Rueegg

Messages: 26
Registered: February 2010

Junior Member

Hi Sebastian,

Thanks for the quick answer - I realized that the OneWhiteSpaceFormatter would solve the problem but was wondering why the serialzier omits whitespaces just for optional keywords.
Is it because the whitespace is connected to the semicolon and therefore omitted as well?
Or is there no particular reason?

Regards

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