[antlr-interest] Fundamental question

[Ian Kaplan]

  There is nothing wrong as far as the syntax goes with this.  There could,
for example, be a user defined type called strig (strings for trigonometry
:).  So this is grammatically correct.  What is not correct is the
semantics.  In fact, there probably is no user defined type strig.  So this
is an error may be issued after the syntax tree is built, when a semantic
phase makes a pass over the tree.  The semantic phase would discover that
there was no type strig and report an error ("No type 'strig' on line 42").


On Wed, Nov 9, 2011 at 8:18 AM, Mari Matinlassi <mmatinlassi at icinetic.com>wrote:

> Hi,
>
> There is something fundamental and important that I have not understood
> with
> ANTLR grammars.
>
> If I need to parse something like...
>
>        int test;
>        strig another;
>        int variable;
>        string here;
>
> You notice there is a typing error on the second line ('strig' instead of
> 'string').
>
> How do I make a grammar that will not stop parsing but, continues after an
> error??
>
> Below is an example how I CANNOT make it work the right way (created AST
> contains only 'int test ;')..
>
> grammar List;
>
> options {
>        language = CSharp3;
>        TokenLabelType = CommonToken;
>        output=AST;
>        ASTLabelType = CommonTree;
> }
>
> @lexer::namespace{ConsoleApplication4}
> @parser::namespace{ConsoleApplication4}
>
>
> public r
>        : variables*
>        ;
>
> variables
>        : type ID ';'
>        ;
>
> type
>        : 'int'
>        | 'string'
>        ;
>
> ID : 'a'..'z' + ;
>
> WS : (' ' |'\n' |'\r' ) {$channel=Hidden;} ;
>
>
> Many thanks for your time and help,
>
> Mari
>
>
>
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