[antlr-interest] multiple tree walkers

Michael Bedward michael.bedward at gmail.com
Sun Feb 8 19:07:43 PST 2009


Hi folks,

I'm working on a little DSL, called jiffle, to create raster images
from maths expressions.  I build an initial AST from the input jiffle
script, and next use a couple of tree walkers to (1) check for
undefined vars and (2) categorize vars on whether thay depend on pixel
position or not.

The grammar for each of these tree-walkers is essentially the same as
that for the token parser, except that only a very small number of
rules / sub-rules have actions.  Everything is working swimmingly at
the moment - but I'm concerned that this approach of cloning a grammar
might be prone to error as the language evolves since it depends on
keeping all of clones in sync.

Are there other approaches / best-practices for writing multiple tree walkers ?

cheers
Michael


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