[antlr-interest] Interpreter built-in functions: code in grammar or use function table?

Michael Bedward michael.bedward at gmail.com
Sun Oct 28 13:22:27 PDT 2012

There would have to be some really pressing reason to do anything
other than a simple table lookup. The other approach seems like the
road to bloated grammars.


On 29 October 2012 06:17, Michael Cooper <tillerman35 at yahoo.com> wrote:
> I need the usual set of built-in functions for my (java-based) interpreter.  Stuff like string manipulation functions, math functions, date functions, etc.
> I'm on a fence about how to implement them.
> On the one hand, I could do it with two simple grammar rules.  One for method invocations and another for function calls.  Then all I would have to
> do is maintain a function table with a list of built-in functions.  I already maintain a function table for functions in the input, so it wouldn't be much of
> a stretch to adapt that to built-in functions as well.
> The other alternative is to define each built-in function in the grammar itself.  E.g. a rule for "println" and another for "substr" and another for "randbetween" etc. etc.
> The advantage to that approach is that they appear in the railroad diagrams in Eclipse.  Those are pretty handy for documentation.  I suppose I could write a
> little helper function to output function definitions to ANTLR-compatible grammar rules.
> Any thoughts?
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