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grammar to permit zipfiles in a string [message #1835654]

Wed, 09 December 2020 15:10

Nils K.

Messages: 13
Registered: November 2020

Junior Member

Hello,

I'm looking into a grammar template to allow zip files like e.g.

"test.zip"
"AA333.zip"
"23test.zip"

My current idea is the following terminal line to do so, but it seems not correct yet. What's wrong? I understand the following line in that way that all figures 0 to 9 or all letter a to z or A to Z are permitted (like the examples above), besides the required ending of ".zip".

terminal zipfile returns ecore::EString:
('a' .. 'z'+ | '0' .. '9'+ | 'A' .. 'Z'+ '.zip')
;

P.S.
Is there any tool around to make this grammar creation easier?

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Re: grammar to permit zipfiles in a string [message #1835657 is a reply to message #1835654]

Wed, 09 December 2020 15:14

Christian Dietrich

Messages: 14566
Registered: July 2009

Senior Member

hi, is there any reason to do this in grammar and not via semantic validation?

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

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Re: grammar to permit zipfiles in a string [message #1835659 is a reply to message #1835657]

Wed, 09 December 2020 15:34

Nils K.

Messages: 13
Registered: November 2020

Junior Member

What do you mean by semantic validation? (Sorry I'm new to xtend/xtext)

Where are semantic validations usually performed in a xtend/xtext project? Can I look for some keywords maybe?

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Re: grammar to permit zipfiles in a string [message #1835660 is a reply to message #1835659]

Wed, 09 December 2020 15:46

Christian Dietrich

Messages: 14566
Registered: July 2009

Senior Member

have a look at the example xtext generates in the wizard

public class MyDslValidator extends AbstractMyDslValidator {
	
	public static final String INVALID_NAME = "invalidName";

	@Check
	public void checkGreetingStartsWithCapital(Greeting greeting) {
		if (!Character.isUpperCase(greeting.getName().charAt(0))) {
			warning("Name should start with a capital",
					MyDslPackage.Literals.GREETING__NAME,
					INVALID_NAME);
		}
	}
	
}

imagine instead of checking for first char is upper you check for the string to end with zip

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

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Re: grammar to permit zipfiles in a string [message #1835662 is a reply to message #1835660]

Wed, 09 December 2020 16:14

Nils K.

Messages: 13
Registered: November 2020

Junior Member

Well, I found the designated files for that purposes and it includes some checks, but none of them include the current checks that may be defined by the grammar file.

My current issue is that the grammar definition is defined by some sort of image definition (ecore file) that needs to be extended to permit zip files.

How can I achieve that via grammar definition?
I thought about this way (adding | '<' zipfile '>' )

Image:
'<' ...existing type.. '>' | '<' zipfile '>'
;

terminal zipfile returns ecore::EString:
('a' .. 'z'+ | '0' .. '9'+ | 'A' .. 'Z'+ '.zip')
;

Does my zipfile definition allow all sorts of names in front of a .zip ending?

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Re: grammar to permit zipfiles in a string [message #1835663 is a reply to message #1835662]

Wed, 09 December 2020 16:24

Christian Dietrich

Messages: 14566
Registered: July 2009

Senior Member

the problem is. lexers in antlr are not quite powerful and they are not context sensitive

thus again: why in grammar.
why not use normal STRING in grammar to parse "test.zip"
and validate it.

or dont you have " at all.
can you then give examples
for the

< > stuff.

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

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Re: grammar to permit zipfiles in a string [message #1836066 is a reply to message #1835663]

Sat, 19 December 2020 15:24

Nils K.

Messages: 13
Registered: November 2020

Junior Member

Thanks for your help. I resolved it and it appears to be an issue with the validation code of the first grammar option. Maybe, that's of help to others anyway and besides the grammar, there might be code elsewhere that leads to errors even it looks like the grammar is the issue on first sight.

[Updated on: Sat, 19 December 2020 15:25]

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