[antlr-interest] Token Stream Rewriting

[Fabien Hermenier]

merge(...) is returning a String.

Fabien.

Le 22/06/11 00:36, Bart Kiers a écrit :
> Fabien, but what is the return type of  this `merge(...)` 
> method? Could you post the method? Or even better: post a SSCCE 
> <http://sscce.org>that causes such an exception?
>
> Regards,
>
> Bart.
>
>
> On Wed, Jun 22, 2011 at 8:30 AM, Fabien Hermenier 
> <hermenierfabien at gmail.com <mailto:hermenierfabien at gmail.com>> wrote:
>
>     In fact, I've badly readed the help. So yet, it is running a
>     String that
>     should be tokenized (then translated into tree I suppose) at run time.
>
>     Le 22/06/11 00:28, Bart Kiers a écrit :
>     > Is your `merge(String, List, String)` method returning
>     > a java.util.ArrayList instead of a Tree?
>     >
>     > Regards,
>     >
>     > Bart.
>     >
>     >
>     > On Wed, Jun 22, 2011 at 8:04 AM, Fabien Hermenier
>     > <hermenierfabien at gmail.com <mailto:hermenierfabien at gmail.com>
>     <mailto:hermenierfabien at gmail.com
>     <mailto:hermenierfabien at gmail.com>>> wrote:
>     >
>     >     Hi
>     >
>     >     I have some troubles with token stream rewriting. Below is the
>     >     piece of
>     >     ANTLR code. I have a grammar, with an AST as output and Java
>     >     as the target. I want to insert a sequence of token into the
>     stream.
>     >
>     >     I have followed the page
>     >
>     http://www.antlr.org/wiki/display/~admin/2007/06/28/Token+stream+rewriting+with+rewrite+rules
>     <http://www.antlr.org/wiki/display/%7Eadmin/2007/06/28/Token+stream+rewriting+with+rewrite+rules>
>     >
>     <http://www.antlr.org/wiki/display/%7Eadmin/2007/06/28/Token+stream+rewriting+with+rewrite+rules>
>     >     and adapted the example that interest me. A piece of the code is
>     >     following. Basically, in the alternative of 'explodedSet', I
>     get the
>     >     return values of other rules and do some stuff in the merge
>     >     method. This
>     >     one returns a list of String as explained in the online example.
>     >
>     >
>     >     explodedSet: '{' (setContent (',' setContent)*)? '}' ->
>     ^(EXPLODED_SET
>     >     setContent+)
>     >         | {List l = new LinkedList();}LEFTY
>     >     r1=brace_content{l.add($r1.ret);} (','
>     >     r2=brace_content{l.add($r2.ret);})* RIGHTY
>     >         -> {
>     >         merge($LEFTY.text,l,$RIGHTY.text)
>     >         };
>     >
>     >     brace_content returns [List ret]:
>     >              st=number ('..' ed=number)? {$ret = new
>     LinkedList(); for
>     >     (int
>     >     i = $st.val; i <= $ed.val; i++) {$ret.add(i);}}
>     >                | NAME {$ret = new LinkedList();
>     $ret.add($NAME.text);};
>     >
>     >     The code compiles well but at runtime, I've got this exception:
>     >
>     >     Caused by: java.lang.ClassCastException: java.util.ArrayList
>     cannot be
>     >     cast to org.antlr.runtime.tree.Tree
>     >         at
>     >    
>     org.antlr.runtime.tree.BaseTreeAdaptor.addChild(BaseTreeAdaptor.java:107)
>     >         at Parser.explodedSet(Parser.java:560)
>     >
>     >     So, the return value of merge does not seems to be converted
>     into
>     >     tokens
>     >     nor Tree. Does someone has an idea ?
>     >
>     >
>     >     Fabien.
>     >
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>     >
>
>
>     --
>     Fabien Hermenier
>     Postdoctoral researcher at Flux
>     http://sites.google.com/site/hermenierfabien/home
>
>
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>


-- 
Fabien Hermenier
Postdoctoral researcher at Flux
http://sites.google.com/site/hermenierfabien/home