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Hidden whitespace causes parsing error [message #629775]

Wed, 29 September 2010 14:18

Jan-Patrick Osterloh

Messages: 3
Registered: September 2010

Junior Member

Hi,

I have a problem with my grammar, and I don't know why. I constructed the following example, that has the same problem:

grammar org.xtext.example.mydsl.MyDsl hidden(WS)

generate myDsl "http://www.xtext.org/example/mydsl/MyDsl"
import "http://www.eclipse.org/emf/2002/Ecore" as ecore

Model: {Model}
NL*
  (
    (greetings+=Greeting) NL
  )*
 ;
	
Greeting:
	'Hello' name=STRING '!' ;

terminal STRING : '\"' ('a'..'z'|'A'..'Z'|'.'|'_'|'#'|':'|'§'|'0'..'9'|'-')* '\"';
terminal WS     : (' '|'\t')*;
terminal NL     : ('\r'? '\n')+;

If I have the following text opened in the editor, a parsing error occours in the third line (mismatched input '\r\n' expecting EOF):

 
Hello "test"!
 
Hello "testa"!

Both lines before the Hello start with a blank and a newline. If I remove the blank in the third line, the error disappears. Unfortunatly I need the NL as part of my grammar, so I cannot add it to the hidden terminals.

Can someone explain why this happen, and how I can solve this problem?

Thanks in advance.
Jan-Patrick

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Re: Hidden whitespace causes parsing error [message #629782 is a reply to message #629775]

Wed, 29 September 2010 14:24

Sven Efftinge

Messages: 1823
Registered: July 2009

Senior Member

Am 9/29/10 4:18 PM, schrieb Jan-Patrick Osterloh:
> Hi,
> I have a problem with my grammar, and I don't know why. I constructed
> the following example, that has the same problem:
> grammar org.xtext.example.mydsl.MyDsl hidden(WS)
>
> generate myDsl "http://www.xtext.org/example/mydsl/MyDsl"
> import "http://www.eclipse.org/emf/2002/Ecore" as ecore
>
> Model: {Model}
> NL*
> (
> (greetings+=Greeting) NL
> )*
> ;
>
> Greeting:
> 'Hello' name=STRING '!' ;
>
> terminal STRING : '\"'
> ('a'..'z'|'A'..'Z'|'.'|'_'|'#'|':'|'§'|'0'..'9'|'-')* '\"';
> terminal WS : (' '|'\t')*;

(unrelated) You should change the quantifier in WS to '+'.

> terminal NL : ('\r'? '\n')+;
>
>
> If I have the following text opened in the editor, a parsing error
> occours in the third line (mismatched input '\r\n' expecting EOF):
>
> Hello "test"!
>
> Hello "testa"!
>
> Both lines before the Hello start with a blank and a newline. If I
> remove the blank in the third line, the error disappears.

NL only recognizes multiple newlines but not two new lines separated
with a blank.

Sven

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