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Some questions. [message #1858007]

Fri, 10 March 2023 16:09

Frank Behr

Messages: 5
Registered: March 2023

Junior Member

I defined this grammar.

grammar org.xtext.dataformat.swiftbankingdsl.SwiftBankingDSL // hidden(WS, ML_COMMENT, SL_COMMENT)

generate swiftBankingDSL "http://www.xtext.org/dataformat/swiftbankingdsl/SwiftBankingDSL"

import "http://www.eclipse.org/emf/2002/Ecore" as ecore

Model:
    SWSyntax += Syntaxitem+;

Syntaxitem: 
    OPEN | FILLER | MULTIROWINDICATOR | SimpleSyntax | CLOSE;
    
SimpleSyntax:
    (FIELDLENGTH FIXEDLENGTHINDICATOR? ALPHACHARACTERSET) | 
    (NEGATIVESIGN? FIELDLENGTH FIXEDLENGTHINDICATOR? NUMCHARACTERSET);

terminal FILLER: ('/'|':');
terminal MULTIROWINDICATOR: ('2'..'9')('1'..'9')* ('*');
terminal FIELDLENGTH : ('1'..'9')('1'..'9')*; 
terminal FIXEDLENGTHINDICATOR: "!";
terminal ALPHACHARACTERSET: ( 'a' | 'x' );
terminal NUMCHARACTERSET: ( 'n' | 'd' );  
terminal NEGATIVESIGN: "[N]";
terminal OPEN: "[";
terminal CLOSE: "]";

It is part of the grammar used to exchange Swift messages. I programmed this in Delphi many years ago. Because I'm curious, I want to try it this way now. :-)
I now have some questions.

1. How can I output something in the XText editor when a terminal or nonterminal has been matched? So basically an event on a rule.
2. How do I translate the expressions of my grammar.
The grammar allows expressions like:

6!n6!n16x/1!a3!a15d or 4*1!n/33x

5!a means e.g. [A-Z]{5}
5a means [A-Z]{1,5}

For example, there are the following translation rules:
OPEN -> (
CLOSE -> )?
'a' -> [A-Z]
'n' -> [0-9]
MULTIROWINDICATOR -> (<the_whole_thing>\n){1,x}

Where can I program such rules?

I care more about understanding. Less about the fact that a productive system is created.

Thanks very much. :-)

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Re: Some questions. [message #1858016 is a reply to message #1858007]

Sat, 11 March 2023 08:55

Christian Dietrich

Messages: 14738
Registered: July 2009

Senior Member

hi, am not sure if i can sort you anyway on the "journey to Xtext" line

i would propose to do the tutorials first and then have a look at the examples that ship with Xtext

from what you wrote:

- your grammar does not produce an ast. Without an ast it is hard to do anything. You should create assignments for attributes and children
- what do you mean by "output in the editor" you may have a look at the interpreter on enter as its done in the arithmetics example or at the code minings in the domain model example
- what do you man by "translate the expressions"?

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de
Day Job: https://www.everest-systems.com

[Updated on: Sat, 11 March 2023 16:20]

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