[gentoo-soc] libbash Weekly Update

[Nathan Eloe]

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I've had a productive week overall, with lots of good progress towards
the final goal of this project.

As the grammar becomes finalized, a change must be made.  All of the
debugging tools are used for grammars that output Java code, but I want
a C/C++ library to handle everything.  So this meant the following things:
1) Grammar file had to work regardless of what the output language was.
2) I needed to know just how the C runtime worked for ANTLR.
3) Since I'm starting to write library code (not just a grammar in a
fancy IDE) I need to document my coding standards for any C/C++ code
written over the next half of the project.

And that indeed is what I've done.  I now have coding style guidelines
(which can be found at http://web.mst.edu/~nwe5g8/coding_standard.pdf,
though as changes are made to the .tex file in the repository, the
guaranteed up to date version of the guidelines can be generated from that).

Also, I've written a quick sample program that parses a single ebuild.
This is mostly a proof of concept, not a final product.  All I was
trying to do was get familiar with the C runtime and see how it worked.

In a previous email I wrote about "infinite loops" in the parser, or at
least loops that I was too impatient to wait to finish (5 minutes is too
long to wait for a parser to finish parsing something).  I found the
problem: I was attempting to recursively aggregate complex strings in
the parser, and the backtracking became too complex for it to handle.
So, I removed the aggregation step, instead just showing the individual
portions of the strings.  Aggregation will be handled by the C++
implementation (which has to do other things with variable expansions in
strings, etc).  So that was a major problem solved, and it tuned the
performance of the parser quite nicely.

The last thing I needed to do was get a language agnostic grammar.  C++
already has functions like exp, and bitor, bitxor, and bitand are C++
keywords.  The runtime doesn't do anything to fix/catch any of this.  As
such I had to go back and do that manually.  However, the changes I made
seemed to make it a grammar that was easier to read.


This week is mostly setup and input.  I'm writing a big bash script that
demonstrates all the features that the grammar supports, and will be
sending the resulting AST to the bash upstream mailing list and the
portage_devs mailing list to see if they have suggestions.  I'm also
going to scour man bash for missing features, set up the build system
for the libbash portion of the code (most likely cmake), Implement a
very simple bash builtin (echo), and finally implement a symbol table.
A busy week, but a week that should leave me in excellent shape for the
rest of the project.

Nate
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