parsley parsing question, how to make a variable grammar

Discussion in 'Python' started by Eric S. Johansson, Jun 13, 2014.

  1. In my quest for making speech friendly applications, I've developed a
    very simple domain specific language/notation that works well. I'm using
    parsley which is a great tool for writing parsers especially simple ones
    like the one I need. However, I've come across a problem that I don't
    know how to solve.

    Below is my grammar. The problem is the last element which aggregates
    all individual grammar elements. In my domain specific notation, it's
    possible for a user to create extensions and I'm trying to figure out
    how to make the grammar accommodate those extensions.

    The first Issue is adding more statements. I can handle that easy enough
    by splitting the existing grammar into a prefix, statements, and
    postfix. I could append more statements to the end of the statement
    section. When I'm done, I can then join all of the pieces together into
    a single grammar.

    The second issue is adding more elements between parentheses of bot so
    the additional statements can be included in the grammar. Seems to me, I
    should be able to create a Python expression which returns the OR list
    and it is interpreted as part of the grammar. Failing that, I'm just
    going to do a %s expansion when I create the grammar.

    I appreciate any insight before I go too far off track.
    --- eric

    TF_grammar = r"""
    kwToken = (letter|digit|'_')+
    uses_statement = 'uses' ws kwToken:kwT ':' <anything*>:roL -> do_uses
    ("".join(kwT), "".join(roL))
    returns_statement = 'returns' ws kwToken:kwT -> do_returns("".join(kwT))
    template_statement = 'template' ws kwToken:kwT -> do_template("".join(kwT))
    remembers_statement = 'remembers' ws kwToken:kwT ->
    everything_else = <anything*>:roL '\n'{0,1} -> do_everything_else
    bot = (uses_statement | returns_statement | template_statement |
    Eric S. Johansson, Jun 13, 2014
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.