Hi folks,
I've finally upgraded my little interpreter from Antlr 3.1 to Antlr
3.3, but I'm getting different behavior in the treewalkers than I did
before and I'm not quite sure what to make of it. Specifically, I have
a rule for parsing if statements in my grammar. It's nothing fancy,
but here is a snippet:
IF condition = root_expression if_then = THEN
{
//do some processing on the expressions
process_this( $condition.eval.getType(), $condition.step);
}
What's odd, however, is that in antlr 3.3, the values I pass into the
condition in my returns statement seem to be null under conditions
that I have not been able to ascertain. For example, in the "Object"
class in my language, I have the following method:
action Compare(Object object) returns CompareResult
CompareResult result
integer myHash = this:GetHashCode()
integer oHash = object:GetHashCode()
if(myHash < oHash) then
result:result = result:SMALLER
end else if myHash = oHash then
result:result = result:EQUAL
end else then
result:result = result:LARGER
end
return result
end
And Antlr fails when it tries to process if(myHash < oHash) then in
the tree walker. However, if I take basically the same code and place
it into another method (e.g., or call it from somewhere, adjust it,
really anything I've thought of), for example:
action Main
CompareResult result
integer myHash = this:GetHashCode()
integer oHash = this:GetHashCode()
if myHash < oHash then
end
end
The exact same comparison does not fail. So far as I can tell, both
work correctly in Antlr 3.1. So, a few questions:
1. Did anything change between these versions that might cause
something like this?
2. Did anything change with the way "returns" are done? I didn't
notice anything in the documentation, but my expression rules in the
tree grammar do lots of stuff like this:
expression returns[ExpressionValue eval, ExecutionStep step]
:
NOT expr = expression
{
//do some processing
$eval = result.getValue();
$step = result.getStep();
}
Do I need to change this to be 3.3 compatible in some way?
Any tips would be appreciated,
Stefik
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