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Author image Jeffrey Kegler
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Marpa::Doc::To_Do - Marpa's To Do List


  • MDLex and MDL will know about Marpa, but not vice versa.

  • I should assume that anyone explicitly using separate recognizer and evaluator stages knows what they are doing. On the other hand, just because they are using the plumbing interface does not mean they want to know about the recognizer/evaluator distinction. When I revise the documentation, I should think accordingly.


  • Create HTML Parser.


  • On ambiguous grammars, it may optimize to save values of reset bocage nodes from the first reset, and simply copy them back in on subsequent resets. In particular for the sorted choices. Note this optimizes only to the degree the user wants multiple parses, or else require multiple interations to get the parse she wants.

  • After MDL is factored out, and stripping & cloning is fully functional, create a matrix of tests of valid grammars vs. their result. Matrix is

        grammars X inputs X clone grammar X clone recognizer X strip grammar X strip recognizer

    Do just one or two inputs per grammar.

  • Add optimizations when max_parses <= 1 For example, no need to prune duplicate parses

  • Add MAX_COUNT for rules. Implement on one of left- and right- recursion only. No immediate need for both.


  • Add a SYNOPSIS to the Plumbing document.

  • When rereading Internals doc, check if parse bocage creation can probably be made a bit slightly cleaner.

  • Make sure that nulling symbols can never be terminals

  • Add code to do cycle rewrite only if there are cycles?


  • Allow action options to be changed when evaluator is created, but not afterwards.

  • Add a trace_choices option? There was an option to trace non-trivial evaluation choices in the old evaluator, and the trace_tasks doesn't entirely replace it.

  • Add a show_derivation option.


  • Allow call to show_tree before first call to value? Should it cause an error message? How about after unsuccessful call to value?


  • MDLex currently does not sort terminals by priority. This means terminal priorities are totally unused. Change this?


MDL is EOL'd.

  • In the MDL grammar, concatenate_lines is called uselessly in a number of places. Eliminate this, for efficiency's sake?

  • bin/mdl in parsing equation.marpa (which is used for many examples in the author.t/Makefile) takes a final return and parses past it, but does not fail.

    The return is NOT in the grammar. What happens is that the call to ::text() is not recognized as a failure, and then the evaluator looks at the last successful parse.

    What to do here? It should be failing, probably. And does the current behavior of the evaluator, (taking the default end as FURTHEST_EARLEME) set the user up for spurious successes.


See the support section in the main module.


Jeffrey Kegler


Copyright 2007 - 2009 Jeffrey Kegler

This program is free software; you can redistribute it and/or modify it under the same terms as Perl 5.10.0.