Gmail and GreaseMonkey

So I finally got around to playing with GreaseMonkey... and I regret not doing it sooner, there's so much I could have done already!

If you're not familiar, GreaseMonkey is a Firefox plugin that lets you add your own/custom javascript code to websites. And it's dead simple - based on a handful of specially formatted comments and a file-naming convention, your javascript becomes custom code you can use to modify any site you want.

I used it to write a scripts for Gmail - when I switched over recently from mutt and pine (I know, to all you text-purists out there: I'm sorry, but I couldn't help it...) I lost the ability to use my nifty cron-based signature auto-rotater. I had written this dead-simple script a while ago to rotate my signature file names every 5 minutes, so essentially every time I sent an email I'd have a different/random sig. Not too useful for business communication, but great for my personal box.

Anyways, Gmail obviously doesn't do this by default, but I managed to get it working with a little bit of custom javascript code via GreaseMonkey in VERY little time... even considering the nasty size (depth) of Gmail's html tree (navigating this with the DOM inspector actually took more time than creating the script).

I'll post a link/the source once I've polished it - at the moment I just have a couple signatures hard-coded in that it chooses from, but I'll add a basic interface for managing signatures as well as post it to userscripts.org and/or SourceForge shortly...

Command-Line Highlighter

I was grepping through some logs the other day at home and I figured "wouldn't it be nice if I could pipe this through something that would highlight lines matching a regex instead of just having grep pull those lines out?" Wouldn't you know it, such a tool doesn't exist, as far as I can tell. Which is very weird, since I've already found it VERY useful...

grep *will* give you context lines if you ask for them explicitly, ie: give me 2 lines before and 4 after the matching line, but I wanted to see ALL the output, with the matches highlighted for easy-spotting.

Anyways, I wrote a little perl script to do the work - it just inserts 'standard' shell color-escape sequences before and after the matching word/line to highlight it (in bright-green-on-black by default... if you're a Matrix fan/l33t hax0r and use a green-on-black setup anyways, there's an option that lets you change the highlighting colors.

It's fairly basic at the moment, but I plan on porting this to C as soon as I have time (possibly tonight) now that it's up on SourceForge, and modify it a bit so that the options/usage syntax matches grep wherever possible/appropriate.

HighLite

XMMS disk_writer plugin patch

This is a (very) small patch I wrote a while ago for the disk_writer plugin of xmms (an open-source X windows media player, modelled after WinAmp). The post in the link is pretty self-explanatory, it's taken from the xmms development list where I sent it... basically it simply modifies how the plugin build the filename to write to so that you get an 'auto-rotate' effect instead of overwriting your previous file recorded from the same source.

Unfortunately, at the time xmms already had a lack of active development, and as far as I can tell is currently no longer an active project. Nevertheless, the patch is there if you're interested/want to take a look, and it does work (I use it myself)...

RFC-Compliant URI Validation

Recently, as part of another project, I needed some code to validate a URI string based on RFC-2396. The goal here was the ability to ensure that a URI was RFC compliant. As such, I decided to use a set of regular expressions which were directly modelled from the ABNF definitions in the RFC. ABNF is by it's nature a very close match for regular expressions in terms of usage, syntax and purpose, and so using them seemed like a logical method of building the URI validation code.

I started by creating an expression for the simplest (and first) definitions in the RFC. 'lowalpha' is defined by the ABNF as being one of the characters a-z inclusive, while 'upalpha' is defined as A-Z inclusive. 'alpha' is defined as either a 'lowalpha' or an 'upalpha' character. 'digit' is defined as one of the characters 0-9 inclusive. Lastly, 'alphanum' is defined as being either an 'alpha' or a 'digit' character. Based on these five definitions, I could create five matching regular expressions which would serve the purpose of indicating whether an arbitrary string matches one of these definitions or not.

<?php

define('LOWALPHA', '[a-z]');
define('UPALPHA', '[A-Z]');

define('ALPHA', '(?:'.LOWALPHA.'|'.UPALPHA.')');
///   (?:[a-z]|[A-Z])

define('ALPHA_OPT', '[a-zA-Z]');

define('DIGIT', '[0-9]');

define('ALPHANUM', '(?:'.ALPHA.'|'.DIGIT.')');
///   (?:(?:[a-z]|[A-Z])|[0-9])

define('ALPHANUM_OPT', '[a-zA-Z0-9]');

?>

The defined expressions ending in _OPT are optimized versions of the regular expression - ie: it's much more efficient to execute a single expression which is a range like [a-zA-Z] than it is to execute two adjacent ranges such as [a-z]|[A-Z].

Within the final implementation, expressions have been optimized where possible but for the most part they mirror the ABNF in the document more or less directly. Almost all the optimization that is present occurs at the lowest level, ie: in the simplest, base expressions from which the further, more complicated expressions are constructed. This approach seems to work since any optimization can loosely be thought of as having an exponential benefit, relative to how low of a level the optimization is performed at.

UriValidator

A New Project

So today I finally decided to start writing a proper blog, after toying with the idea on and off for a little while. Among other things, I want all of the random code I write to be freely available and accessible somewhere online under the GPL and it doesn't always fit nicely into existing projects/categories/paradigms/etc. I'll still send and/or upload whatever I can where an appropriate project exists somewhere, but this gives me a nice way to keep everything referenced from one place, regardless of what it is. Yes, I know - I could just upload everything into it's own project on SourceForge or something, but this also lets me explain everything and talk about stuff in an informal way. It also provides space for me to talk about programming and related topics in general, and gives me somewhere to post random thoughts and opinions on the world of software development. Lastly, I believe the whole idea of open source shouldn't be limited to the actual source itself - the whole process of creating software should be an organic, open, and cooperative activity in most cases, and so I'll be using this to document the life of my various projects, from start to 'release'.