Improve SyntaxTree / C / math expression parser

[translunar]

SyntaxTree (ext/nmatrix/generator/syntax_tree.rb) supports only very simple mathematical expressions. I'd like it if it could handle more complicated stuff.

That probably means finding a library with few or no dependencies which can parse C. It's possible you could derive your own from SyntaxTree, though this doesn't really even support parentheses.

It'd also be nice if it understood things like absolute value functions -- or really anything else you might find in NETLIB's BLAS subroutines.

[translunar]

I've found a really great C AST parser, called -- fittingly -- CAST.

gem install cast19 # Ruby 1.9 version

I'm playing around with it as I write this.

[translunar]

I wrote this, but @chriswailes recommends using C++ templates embedded in extern "C" {} blocks.