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Álvaro  
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 More options Nov 15 2012, 11:35 am
From: Álvaro <avalormaqued...@gmail.com>
Date: Thu, 15 Nov 2012 17:35:27 +0100
Local: Thurs, Nov 15 2012 11:35 am
Subject: Re: [erlang-questions] Question of yecc
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Hi,

I think the problem is that yecc does not recognize the terminal 'num'.
The default scanner recognizes 'integer' and 'float'.
Change your 'num' for 'integer' and try again.

Best,
Álvaro

2012/11/15 Solomon <solomon....@gmail.com>

> I want to write a parser to parse the string like this:
>   a.id = b.id
>   a.id = 10

> My yrl file like this:
> *Nonterminals
>     val expr alias field.

> Terminals
>     '=' '>' '>=' '<=' '<' '!=' '.' 'atom'
>     'num'.

> Rootsymbol
>     expr.

> expr->val '=' val:['$1', '$3', {'opt', '='}].
> expr->val '>' val:['$1', '$3', {'opt', '>'}].
> expr->val '>=' val:['$1', '$3', {'opt', '>='}].
> expr->val '<' val:['$1', '$3', {'opt', '<'}].
> expr->val '<=' val:['$1', '$3', {'opt', '<='}].
> expr->val '!=' val:['$1', '$3', {'opt', '!='}].

> val->alias '.' field:{'$1', '$3'}.
> val->num:{'num', '$1'}.

> alias->atom:{'alias', '$1'}.
> field->atom:{'field', '$1'}.*

> it is ok for "a.id=b.id":
> *{ok,[{{alias,{atom,1,a}},{field,{atom,1,id}}},
>      {{alias,{atom,1,b}},{field,{atom,1,id}}},
>      {opt,'='}]}*

> and it is ok for "a.id=b":*
> {ok,[{{alias,{atom,1,a}},{field,{atom,1,id}}},
>      {num,{atom,1,a}},
>      {opt,'='}]}*

> but it error for "a.id=12":
> *{error,{1,my_parser,["syntax error before: ","12"]}}*

> what is wrong with my yrl file?

> _______________________________________________
> erlang-questions mailing list
> erlang-questi...@erlang.org
> http://erlang.org/mailman/listinfo/erlang-questions

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