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Newbie-- JVM Language-Extend Xbase and add joda.time.Interval as literal and add new operators [message #1723000]

Wed, 10 February 2016 18:17

Dildar Mising name

Messages: 4
Registered: April 2011

Junior Member

Hi All,

I am new to XText, Xtend and Xbase. I have reviewed practically all the material available on the internet. I am working on creating a new JVM DSL by inheriting Xbase grammar and adding 'temporal' syntax by incorporating joda.time.Interval.

The idea is to have literals and/or expressions that will help in a variety of situations dealing with the "interval" like constructs such as time periods.

I am trying to make some design decisions and will definitely benefit from your experience.

My questions is as follows:
i. Create new operators and Literals or ii. Use Expressions with statically imported methods?

I am trying to use the first approach and not finding much guidance about creating new operators on the internet. As an experiment, in my grammar I redefined:

OpCompare:
super
| '|-|' // equals
| '|>-' // starts
| '>-|' // finishes
| '|||' // overlaps
| '<->' // meets
| '<-|' // before
| '|->' // after
;

When I run the generated DSL and try to use one of these operators I get

"|-| cannot be resolved."

Please point me to the right direction.

In the mean time, I will work on using ImplicitlyImportedFeatures so that methods such as "overlaps", "meets" etc become available without having to import and with better integration with my DSL.

Thanks in advance.

Dildar

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Re: Newbie-- JVM Language-Extend Xbase and add joda.time.Interval as literal and add new operators [message #1723005 is a reply to message #1723000]

Wed, 10 February 2016 18:40

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

Have a look at

- OperatorMapping (this class maps Operators to Methods)
- ImplicitlyImportedFeatures (this class lets you add implicit extension classes)

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: Newbie-- JVM Language-Extend Xbase and add joda.time.Interval as literal and add new operators [message #1723024 is a reply to message #1723005]

Thu, 11 February 2016 05:31

Dildar Mising name

Messages: 4
Registered: April 2011

Junior Member

I see a sample for using ImplicitlyImportedFeatures in the "BuildDsl" example from the Seven JVM languages but it seems it works with 2.7 and the configuration is a bit different from 2.9 defaults. Do you recommend I change the default configuration to look more like "BuildDsl" example?

I am wondering if it is possible to gen the required stubs for ImplicitlyImportedFeatures and hook them up with the runtime module. I did this manually but I am not sure if I missed anything. Everything compiles fine.

Also, I see a warning:

"Discouraged access: The type ImplicitlyImportedFeatures is not accessible due to restriction on required project ...". I went ahead and ignored it. Has something changed since 2.7 in this area? Or can I go ahead and change the access rules?

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Re: Newbie-- JVM Language-Extend Xbase and add joda.time.Interval as literal and add new operators [message #1723025 is a reply to message #1723024]

Thu, 11 February 2016 06:15

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

Xtext may have 1000 extension points (this is just a wild guess) so
generating stubs for all of them would be a mess. Thus the "add a binding
manually" pattern is fine and good practice for non standard extension
points. The api warning you can ignore if you can live with potential api
changes in future xtext releases

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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