[antlr-interest] trees with payloads??
John D. Mitchell
johnm-antlr at non.net
Wed Nov 10 14:11:48 PST 2004
>>>>> "Terence" == Terence Parr <parrt at cs.usfca.edu> writes:
[...]
> After Loring bitched at me on the phone yesterday <snicker>, I'm
> beginning to think he's right: if separating the node data from the
> navigation is the right concept, then trees should be a single
> implementation that simply carry a "payload" object defined by the user.
> This is like Sun's MutableTreeNode.
Go Loring! :-? :-)
I strongly concur.
[...]
> As a bonus to the payload strategy, we can enhance the tree functionality
> later w/o forcing alterations in people's application; their payload
> objects still fit in our nodes.
Yea!
> This all comes at the cost of an additional object creation (payload
> creation + node creation).
In Java, who cares.
For people who care (embedded C), the code gen could be made smart enough
to do just one single allocation for both "objects".
> Side note: Mitchell suggested Tokens and Tree nodes should have not only
> fixed fields like this, but the ability to dynamically acquire
> "attributes"; this would basically be a hashmap. It cuts down on a
> bazillion subclasses. It would be useful when parsing xml for example.
> The TAG token could have a list of tag attributes w/o creating subclasses
> etc...
Yeah, that's a damn good idea! :-?
LinkedHashSet is your friend.
Have fun,
John
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