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How to deal with keywords that are not really reserved? [message #675589]

Tue, 31 May 2011 23:32

Alex Ruiz

Messages: 103
Registered: March 2011

Senior Member

Greetings,

In my grammar, I specified the following definitions:

Message:
  'message' name=ID '{'
  elements+=MessageElement*
  ('extensions' extensionsFrom=INT 'to' (extensionsTo=INT | 'max') ';')?
  '}'(';')?;

MessageElement:
  Type | Property | Group | ExtendMessage | Option;

Property:
  modifier=Modifier type=AbstractTypeReference name=ID '=' index=INT ';';

According to this grammar, "message" a keyword. It turns out that the language allows 'message' to be a valid name for names of properties!!! so I can also have a property like this:

optional string message = 2;

and right now, the editor is giving me a syntax error. Is there any way to specify that keywords can be used in other context?

Many thanks in advance,
-Alex

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Re: How to deal with keywords that are not really reserved? [message #675627 is a reply to message #675589]

Wed, 01 June 2011 03:58

Alexander Nittka

Messages: 1193
Registered: July 2009

Senior Member

Hi,

the standard way is escaping the keyword, i.e. writing ^message instead of message, when it is used as ID rather than as a keyword. "^" is dealt with by the the value converter for ID, i.e. it is removed when parsing and added when serialising.

If you don't want the escaping, things become more complicated:
You have to use a datatype rule

IdOrKeyword: ID|'message'|listOfAllOtherKeywordsAllowedAsID;

and use that rule wherever you would use ID (and want the keywords allowed). However, the keywords will be highlighted as such wherever they appear (even if used as id), so you would have to adapt semantic highlighting as well.

Alex

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(no subject) [message #675643 is a reply to message #675627]

Wed, 01 June 2011 04:49

Ed Willink

Messages: 7655
Registered: July 2009

Senior Member

Hi

And if there are some keywords not in listOfAllOtherKeywordsAllowedAsID,
you will still need to escape them which will require a custom
ValueConverterService.

Regards

Ed Willink

On 01/06/2011 04:58, Alexander Nittka wrote:
> Hi,
>
> the standard way is escaping the keyword, i.e. writing ^message
> instead of message, when it is used as ID rather than as a keyword.
> "^" is dealt with by the the value converter for ID, i.e. it is
> removed when parsing and added when serialising.
>
> If you don't want the escaping, things become more complicated:
> You have to use a datatype rule
>
> IdOrKeyword: ID|'message'|listOfAllOtherKeywordsAllowedAsID;
>
> and use that rule wherever you would use ID (and want the keywords
> allowed). However, the keywords will be highlighted as such wherever
> they appear (even if used as id), so you would have to adapt semantic
> highlighting as well.
>
> Alex

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