[antlr-interest] RES: RES: Dangling ELSE on Cobol

[Juancarlo Añez]

How is 'ELSE' defined?

-- Juanca

On Thu, Sep 27, 2012 at 8:14 AM, Nilo Roberto C Paim <nilopaim at gmail.com>wrote:

> Hi, Kevin.
>
> You were right about the changes. Thanks for your interest.
>
> But with the following syntax:
>
> ifCmd
>   :
>   IF boolExpr command+
>   (
>     ELSE command+
>   )?
>   ;
>
> When I input something like:
>
>    IF (a > b)
>       Close z
>       Call x
>    ELSE
>       Open y.
>
> The parser shows me:
>
> line 204:11 no viable alternative at input 'call x'
> line 204:11 extraneous input 'ELSE' expecting {'.', 'call', 'close',
> 'open'}
>
> If I remove the "else" and the following line from the input, everything
> parses without errors (but obviously, that´s not what I need...).
>
> Any hints?
>
> TIA.
> Nilo - Brazil
>
> -----Mensagem original-----
> De: Kevin Cummings [mailto:cummings at kjchome.homeip.net]
> Enviada em: quarta-feira, 26 de setembro de 2012 23:38
> Para: Nilo Roberto C Paim
> Cc: Juancarlo Añez; antlr ANTLR
> Assunto: Re: [antlr-interest] RES: Dangling ELSE on Cobol
>
> I don't think you need it at all.  Just remove the => and everything
> before it.
>
> --
> Kevin J. Cummings
> kjchome at verizon.net
> cummings at kjchome.homeip.net
> cummings at kjc386.framingham.ma.us
> Registered Linux User #1232
> (http://www.linuxcounter.net/)
>
>
> On Sep 26, 2012, at 12:56, "Nilo Roberto C Paim" <nilopaim at gmail.com>
> wrote:
>
> > Hi, all.
> >
> >
> >
> > Does anyone knows how is this supposed to be in Antlr V4? The “=>”
> > gave me syntax error…
> >
> >
> >
> > No, I’ve not buy the book yet, but I intend to do soon…
> >
> >
> >
> > TIA,
> >
> > Nilo - Brazil
> >
> >
> >
> > De: juancarlo.anez at gmail.com [mailto:juancarlo.anez at gmail.com] Em nome
> > de Juancarlo Añez Enviada em: sexta-feira, 21 de setembro de 2012
> > 14:11
> > Para: Nilo Roberto C Paim
> > Cc: antlr ANTLR
> > Assunto: Re: [antlr-interest] Dangling ELSE on Cobol
> >
> >
> >
> > Nilo,
> >
> >
> >
> > It's a lot of lookahead, but it solves your problem:
> >
> >
> >
> > command :
> >
> >    ifCmd
> >
> >    | 'INIT'
> >
> >    | 'MOVE'
> >
> >    ;
> >
> >
> >
> > ifCmd:
> >
> >    'IF' 'EXPRE' ((command)=>command)+
> >
> >    (
> >
> >        ('ELSE')=> 'ELSE' ((command)=>command)+
> >
> >    |
> >
> >        ()
> >
> >    )
> >
> >    ;
> >
> >
> >
> > The ambiguity warning were saying that ANTLR didn't know to which
> nesting level to add the next "command". The lookaheads tell it to be
> greedy and match them against the closest IF or ELSE.
> >
> >
> >
> > Cheers,
> >
> >
> >
> > -- Juanca
> >
> >
> >
> > On Thu, Sep 20, 2012 at 2:50 PM, Nilo Roberto C Paim <nilopaim at gmail.com>
> wrote:
> >
> > Hi, folks.
> >
> > I'm trying to parse Cobol sources using Antlr 3.4 (ANTLR Parser
> > Generator
> > 3.4 Jul 19, 2011 11:35:12. actually).
> >
> > I'm stuck with the old dangling ELSE problem. Here the relevant piece
> > of code of my grammar that shows me the problem:
> >
> >
> >        command :
> >                ifCmd
> >                |       initializeCmd
> >                |       moveCmd
> >                |       openCmd
> >                ;
> >
> >        ifCmd:
> >                        IF expr command+ ( (ELSE)=> ELSE command+)?
> >                ;
> >
> >
> > I cannot put a terminator on the commands 'cause commands in Cobol may
> > end or with a '.' or with the following command. This is true
> > including the ifCmd itself.
> >
> > The code above shows me the following messages:
> >
> > warning(200): /SuperCobol/src/SC.g:229:13:
> > Decision can match input such as "IF" using multiple alternatives: 1,
> > 2 As a result, alternative(s) 2 were disabled for that input
> > |---> IF expr command+ ( (ELSE)=> ELSE command+)?
> >
> > warning(200): /SuperCobol/src/SC.g:229:13:
> > Decision can match input such as "MOVE" using multiple alternatives:
> > 1, 2 As a result, alternative(s) 2 were disabled for that input
> > |---> IF expr command+ ( (ELSE)=> ELSE command+)?
> >
> > warning(200): /SuperCobol/src/SC.g:229:13:
> > Decision can match input such as "OPEN" using multiple alternatives:
> > 1, 2 As a result, alternative(s) 2 were disabled for that input
> > |---> IF expr command+ ( (ELSE)=> ELSE command+)?
> >
> > warning(200): /SuperCobol/src/SC.g:229:13:
> > Decision can match input such as "INITIALIZE" using multiple
> alternatives:
> > 1, 2
> > As a result, alternative(s) 2 were disabled for that input
> > |---> IF expr command+ ( (ELSE)=> ELSE command+)?
> >
> > warning(200): /SuperCobol/src/SC.g:229:38:
> > Decision can match input such as "IF" using multiple alternatives: 1,
> > 2 As a result, alternative(s) 2 were disabled for that input
> > |---> IF expr command+ ( (ELSE)=> ELSE command+)?
> >
> > warning(200): /SuperCobol/src/SC.g:229:38:
> > Decision can match input such as "MOVE" using multiple alternatives:
> > 1, 2 As a result, alternative(s) 2 were disabled for that input
> > |---> IF expr command+ ( (ELSE)=> ELSE command+)?
> >
> > warning(200): /SuperCobol/src/SC.g:229:38:
> > Decision can match input such as "OPEN" using multiple alternatives:
> > 1, 2 As a result, alternative(s) 2 were disabled for that input
> > |---> IF expr command+ ( (ELSE)=> ELSE command+)?
> >
> > warning(200): /SuperCobol/src/SC.g:229:38:
> > Decision can match input such as "INITIALIZE" using multiple
> alternatives:
> > 1, 2
> > As a result, alternative(s) 2 were disabled for that input
> > |---> IF expr command+ ( (ELSE)=> ELSE command+)?
> >
> >
> > 8 warnings
> >
> > Please, any hints?
> >
> > Thanks in advance,
> > Nilo
> > Brazil
> >
> >
> > List: http://www.antlr.org/mailman/listinfo/antlr-interest
> > Unsubscribe:
> > http://www.antlr.org/mailman/options/antlr-interest/your-email-address
> >
> >
> >
> >
> >
> >
> >
> > --
> > Juancarlo Añez
> >
> >
> > List: http://www.antlr.org/mailman/listinfo/antlr-interest
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>
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-- 
Juancarlo *Añez*