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Rule for enclosing a value in apostrophes [message #1068140]

Fri, 12 July 2013 11:53

Tobias Freudenreich

Messages: 19
Registered: July 2013

Junior Member

Hi,

I am trying to write a rule that (as part of my language) supports statements like

(keyword='value')

I have the rules

Statement:
	"(" attribute=Attribute "=" state=AttributeValue ")"
;

Attribute:
	ID
;

AttributeValue:
	"'" ID "'"
;

The problem I am facing is that the generated editor complains about statements like test='hi'. Reporting that "mismatched input 'hi' expecting ''' "

If I replace the last rule with

AttributeValue:
	"!" ID "!"
;

the generated editor accepts test=!hi!. So I assume that I am somehow treating ' wrong. Does anyone know how to correctly handle this? I have no custom terminal rules (just the ones imported from the Terminals file).

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Re: Rule for enclosing a value in apostrophes [message #1068143 is a reply to message #1068140]

Fri, 12 July 2013 12:09

Alexander Nittka

Messages: 1193
Registered: July 2009

Senior Member

Hi,

the definition collides with the STRING terminal definition. Is there a reason not to use STRING directly?

Alex

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Re: Rule for enclosing a value in apostrophes [message #1068155 is a reply to message #1068143]

Fri, 12 July 2013 12:52

Ed Willink

Messages: 7655
Registered: July 2009

Senior Member

Hi Alex

The default STRING terminal supports "..." and '...' strings.

terminal STRING :
'"' ( '\\' ('b'|'t'|'n'|'f'|'r'|'u'|'"'|"'"|'\\') |
!('\\'|'"') )* '"' |
"'" ( '\\' ('b'|'t'|'n'|'f'|'r'|'u'|'"'|"'"|'\\') |
!('\\'|"'") )* "'"
;

If this is not what you want, you need to define/inherit a custom
variant of org.eclipse.xtext.common.Terminals that perhaps does

terminal STRING :
'"' ( '\\' ('b'|'t'|'n'|'f'|'r'|'u'|'"'|"'"|'\\') |
!('\\'|'"') )* '"'
;
terminal SINGLE_QUOTED_STRING :
"'" ( '\\' ('b'|'t'|'n'|'f'|'r'|'u'|'"'|"'"|'\\') |
!('\\'|"'") )* "'"
;

It is worth preserving as many of the standard terminal names as
possible since there is helpful built-in functionality for ID etc.

You will however need to reference and implement a ValueConverterService
to make SINGLE_QUOTED_STRING work as required.

Regards

Ed Willink

On 12/07/2013 13:09, Alexander Nittka wrote:
> Hi,
>
> the definition collides with the STRING terminal definition. Is there
> a reason not to use STRING directly?
>
> Alex

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