[antlr-interest] String template questions.

[PSheehan at decaresystems.ie]

I've got a simple grammar up and running which generates Java beans and 
Hibernate config files.  I have a few questions as I'm not really sure if 
I am going about things in the correctly way.  My solution uses a lexer 
and parser to create an AST which I then pass on to a tree walker for the 
generation of the output.

1.  How do people generally create multiple files from a single  tree 
output.  For example if the result of the tree needs to create Bean1.java 
and Bean2.java.  Currently I've created a streamer strategy which my tree 
walker calls when it needs be, passing the output of a template to it. The 
strategy then knows how to create java files in the correct package 
structure.  I can then easily change the strategy in order to write 
Hibernate config files.  Is this a valid approach or should I just get the 
tree walker to roll up all the template results and break them up after 
the walker has finished.

2.   I've created one entry point into my templates from my grammar like 
so '%modeltmp($namespace,$name,$fieldDefinations)'.  Only one rule in the 
tree walker invodes a grammar, the other rules just gather the information 
needed to pass to the template. The main reason I did this was so I could 
call different templates from within the main template to produce 
different output given the same input.  For example I could generate a 
constructor, bean properties and a 'toString' method all from 
$fieldDefinations.    Is there a better way of doing this?  Should I move 
some of this work back into my parser so it creates, in the AST, a 
constructor node with field definations as childern or a 'toString' node 
with field definations as childern etc.

Here is a snippet of what I'm doing in the tree grammar.

model 
scope{
    ArrayList fieldDefList;
}
@init{
    $model::fieldDefList=new ArrayList();
}
        :       ^(MODEL TYPE fs+=fielddef+) 
                    {
                        StringTemplate 
temp=%modeltmp(namespace={$stat::namespaceDef},name={$TYPE},fields={$model::fieldDefList});
 streamer.write($stat::namespaceDef,$TYPE.text,temp.toString());
                    }
        ;

fielddef
        :       ^(FIELD TYPE ID) {$model::fieldDefList.add(new 
SimpleFieldType($TYPE.text,$ID.text));}
        ;

namespace
        :       ^(NAMESPACE ^(NAMESPACEMETA (ids+=ID)+)) 
{$stat::namespaceDef=$ids;}
        ;

Thanks,
Paul

 


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