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Parse an absolut path [message #1066941]

Fri, 05 July 2013 08:22

kon f

Messages: 152
Registered: March 2012

Senior Member

Hey,

I'm trying to parse an absolute path that starts with /. It seems to be pretty tricky then I actually thought:

Path:
	'/' VALUE_WITHOUT_SLASH (VALUE_WITH_SLASH)*;

terminal VALUE_WITHOUT_SLASH:
	(CHARACTER)+;

terminal VALUE_WITH_SLASH:
	(CHARACTER | '/')+;

terminal fragment CHARACTER:
	('a'..'z' | 'A'..'Z' | '_' | '0'..'9' | '\\' | '\\(' | '\\)' | '\\ ' | '\\@');

I need to make sure that Path starts with a / that is why I differ between the value with and without the slash. I also thought about:

Path:
	'/' VALUE_WITH_SLASH+;

But this would allow e.g. //. How to I specify the following rule ('/' CHARACTER+)+.

Thank you.

Kon

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Re: Parse an absolut path [message #1066972 is a reply to message #1066941]

Fri, 05 July 2013 09:57

Alexander Nittka

Messages: 1193
Registered: July 2009

Senior Member

Hi,

as a general pattern, you might look at the qualified name definition. Don't mess with terminals if you don't really have to. You can always implement validation (or value conversion) in order to make sure that the path has the correct syntax

Path: "/" ID ("/" ID)*;

Alex

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Re: Parse an absolut path [message #1067433 is a reply to message #1066972]

Mon, 08 July 2013 16:20

kon f

Messages: 152
Registered: March 2012

Senior Member

Hey Alexander,

thank you! I also added hidden() to omit white spaces between the / and the ID parse rule (that are inherited from Terminals.xtext).

Path hidden(): 
       "/" ID ("/" ID)*;

Thank you.

Kon

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