topfew-rs: Rust implementation of Tim Bray's topfew tool

Tim Bray recently blogged about topfew, his Go implementation of a tool to replace the awk '{print $1}' access_log | sort | uniq -c | sort -rn | head -12 pipeline. This is a reimplementation of that tool in idiomatic stable Rust.

The initial Rust version was 2.9x faster than Tim's Go implementation; current master appears to be around 6.7x faster thanks to some additional optimizations. The Rust version currently has slightly fewer non-test SLOC than the Go version. Thanks to Thomas Andreas Jung for contributing substantial performance improvements.

``` topfew 0.1.0

USAGE: tf [OPTIONS] --fields

FLAGS: -h, --help Prints help information -V, --version Prints version information

OPTIONS: -f, --fields Fields to use as part of the line's key -n, --num Top number of matches to show [default: 10] -e, --regex Regular expression used to split lines into fields [default: [ \t]]

ARGS: File to search ```

If you have the Rust toolchain installed, you can install it with cargo install topfew.