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Keyword with whitespace [message #1836212]

Thu, 24 December 2020 11:07

Alex Gor

Messages: 159
Registered: November 2014
Location: Russia

Senior Member

Dears

XText is able to support keyword with whitespaces

In case I write in grammar something like :

MY_KEYWORD:
	"KeywordStart KeywordSecond"
;

Xtext suggests me to rewrite as

MY_KEYWORD:
	"KeywordStart"  "KeywordSecond"
;

But seems to me it is not fully corresponded

Thank you in advance

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Re: Keyword with whitespace [message #1836230 is a reply to message #1836212]

Fri, 25 December 2020 07:27

Uli Merkel

Messages: 250
Registered: June 2013

Senior Member

I think it is because the parser
treats multiple whitespace characters as one.
So the suggested one is more meaninful.

Happy new year, Uli

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Re: Keyword with whitespace [message #1836234 is a reply to message #1836212]

Fri, 25 December 2020 10:47

Alex Gor

Messages: 159
Registered: November 2014
Location: Russia

Senior Member

There is more common question. Lexer and parser take whitespace into account as delimiter and remove it .

So if we using xtext as platform can we create a grammar where keyword will contains whitespace

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Re: Keyword with whitespace [message #1836237 is a reply to message #1836234]

Fri, 25 December 2020 15:40

Ed Willink

Messages: 7655
Registered: July 2009

Senior Member

Hi

If you really really want precise sequences of whitespace in keywords you can probably do it, but make sure that you do not inherit the default hidden WS and beware that you will have to manually handle token separation yourself.

If you really want arbitrary whitespace in keywords you may choose to use a datatype rule to treat the compound letters and whitespace as a production. You will still need to handle all WS explicitly.

If there are a few multi-word keywords then you can simply specify e.g. 'abstract' 'static' in your grammar and work as normal. More likely the multiples have subtle semantics and you should sit back and reconsider what made you think you ever wanted whitespace in keywords in the first place.

Happy Xmas

Ed Willink

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