Eclipse Community Forums: TMF (Xtext) » Same rule multiple times

Help

Home

Home » Modeling » TMF (Xtext) » Same rule multiple times

Show: Today's Messages :: Show Polls :: Message Navigator

Same rule multiple times [message #1710087]

Sun, 04 October 2015 06:45

Mihael Schmidt

Messages: 81
Registered: August 2010

Member

Hi,

sorry for this beginner questions but I can't wrap my head around it.

I have the following dsl:

/* this is a comment */
/* another comment*/

start
/* comment */
statements
split +
  statement
/* comment */
another_statement
end

Comments can occur almost everywhere, before the start, between statements, ...

I started with the grammar:

Program:
	'start'
	statements+=Statement*
	'end';

Statement:
	Comment |
	Command;

Command:
	name=ID;

Comment:
	'/*' content=ID '*/';

But this doesn't cover the cases where the comments are before the start or even after the end.

Thanx in advance.

Mihael

Report message to a moderator

Re: Same rule multiple times [message #1710101 is a reply to message #1710087]

Sun, 04 October 2015 08:49

Christian Dietrich

Messages: 14718
Registered: July 2009

Senior Member

is it intended to have the comments explicitely?

Program:
         statements+=Comment*
	'start'
	statements+=Statement*
	'end'
        statements+=Comment*
;

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

Report message to a moderator

Re: Same rule multiple times [message #1710141 is a reply to message #1710101]

Mon, 05 October 2015 06:09

Mihael Schmidt

Messages: 81
Registered: August 2010

Member

Yes. I need the comments (explicitly? any other option?).

Syntax for comments is /* some text */. But /* -> */ is added to the hidden terminals (ML_COMMENT) . Does that mean that these terminals are excluded? How would I "unhide" it?

Thanx in advance

Mihael

Report message to a moderator

Re: Same rule multiple times [message #1710144 is a reply to message #1710141]

Mon, 05 October 2015 06:16

Christian Dietrich

Messages: 14718
Registered: July 2009

Senior Member

you can list the hidden token in the hidden(TOKEN1,.....,TOKENN) clause on grammar or rules

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

Report message to a moderator

Re: Same rule multiple times [message #1710149 is a reply to message #1710144]

Mon, 05 October 2015 06:32

Mihael Schmidt

Messages: 81
Registered: August 2010

Member

Sorry for being a little bit dumb on this but adding the ML_COMMENT to hidden would actually hide it (as it is by default). I need to not have it hidden. Do I have to use my own grammar for this?

Report message to a moderator

Re: Same rule multiple times [message #1710152 is a reply to message #1710149]

Mon, 05 October 2015 06:45

Christian Dietrich

Messages: 14718
Registered: July 2009

Senior Member

no simply remove ML_COMMENT from the hidden list of the grammar

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

Report message to a moderator

Re: Same rule multiple times [message #1710155 is a reply to message #1710152]

Mon, 05 October 2015 06:56

Mihael Schmidt

Messages: 81
Registered: August 2010

Member

declaring a new set of hidden tokens on the top rule did the trick thanks. also now found the section "Hidden Terminal Symbols" in the documenation. =)

Report message to a moderator

Re: Same rule multiple times [message #1710402 is a reply to message #1710155]

Tue, 06 October 2015 12:47

Sven Efftinge

Messages: 1823
Registered: July 2009

Senior Member

Note that you can also leave the ML_COMMENT rule hidden so you can have comments everywhere and don't need to deal with them throughout the grammar.
Although in that case the comments won't be part of the AST (i.e. the resulting EMF model), there is the parse tree (the node model) that still contains them. So you can obtain them from there when needed.
There is for instance the DocumentationProvider that gives you the comment preceding a given element.

Sven

Report message to a moderator