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problem with using enums as optional elements [message #760200]

Thu, 01 December 2011 10:26

Joerg Thiemer
Messages: 6
Registered: July 2010

Junior Member

Hi,

I have a problem with the use of enums and processing the grammar. I'm not using XTend, I'm using java directly.

My dsl is like this

...
ItemVisualization:
'item' id=ID
'type' dbType=DBTYPE
('caption' caption=STRING)?
('align' align=ALIGNTYPE)?
...
;

enum ALIGNTYPE :
H2 = 'h2' |
B2 = 'b2' |
K1 = 'k1'
...

While processing the DSL I can use the question ...getCaption()!=null ... to test whether the optional element caption is used or not.
In the case of align this did'nt work, getAlign() is not null and getAlign().getLiteral() deliver the first value of the enum ('h2').

How can I check wether th optional align was used or not?

Thanks

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Re: problem with using enums as optional elements [message #760210 is a reply to message #760200]

Thu, 01 December 2011 10:46

Alexander Nittka
Messages: 1081
Registered: July 2009

Senior Member

Hi,

at least 2 possibilities:
-you can introduce an artificial enum (default value) UNSET (first of the list
-you can bind the align keyword to a boolean feature (isAlignSet?='align' align=...)

Alex

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Re: problem with using enums as optional elements [message #760235 is a reply to message #760210]

Thu, 01 December 2011 11:37

Christian Dietrich
Messages: 4426
Registered: July 2009

Senior Member

Hi,

you can use a manually maintained metamodel with an unsettable eattribute
maybe you can use the metamodel postprocessor to make the eattribute unsettable too

~Christian

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Re: problem with using enums as optional elements [message #760358 is a reply to message #760200]

Fri, 02 December 2011 01:33

Joerg Thiemer
Messages: 6
Registered: July 2010

Junior Member

Hi,

Cool!
Thank you for your quick reply.

I tried the binding to a boolean feature and it works fine.

Joerg

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Re: problem with using enums as optional elements [message #760428 is a reply to message #760358]

Fri, 02 December 2011 05:55

Meinte Boersma
Messages: 429
Registered: July 2009
Location: Leiden, Netherlands

Senior Member

You should be able to use the EObject#isSet method as well. Something like this should work (untested):

instance.eIsSet(instance.eClass().getEStructuralFeature("caption"))

Xtext blogs: executable models...again? | workshop material | custom scoping with Xtend

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Re: problem with using enums as optional elements [message #1016985 is a reply to message #760428]

Fri, 08 March 2013 08:34

Robert Wild
Messages: 26
Registered: August 2012

Junior Member

Meinte Boersma wrote on Fri, 02 December 2011 05:55

You should be able to use the EObject#isSet method as well. Something like this should work (untested):
instance.eIsSet(instance.eClass().getEStructuralFeature("caption"))

This doesn't work for the first element in the enum. eIsSet will return false, if the first enum value is specified.

I used UNSET as first element in the list and hid it from ContentAssist.

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