State Machines in Rust

A presentation which introduces a few different techniques for implementing state machines in Rust.

• tennis kata

  • naive implementation
  • naive implementation using enumeration for score
  • a state machine solution
    • fixing problems with naive solution
  • another state machine solution
    • uses minimal memory
    • uses type system to prevent invalid transitions
  • iterating on 20-state solution to replace big match statement with a dynamic dyn call
    • improves performance
    • reduces cognitive load
  • iterating on 20-state solution to replace big match statement with a table lookup
    • improves performance over big match statements
    • best performance?
    • reduces cognitive load

• super simple state machine

  • redemonstrate technique from tennis kata on simple state machine

• type state pattern

  • useful idiom for implementing stateful interfaces
  • prevents incorrect use of stateful interfaces

• asynchronous state machine parser

  • a state machine driven parser
  • uses function pointers to force a jump table

Tennis Kata Images

Use graphviz to generate images for tennis kata state machines:

$ circo -Tpng -o sm4.png sm4.dot
$ dot -Tpng -o sm20.png sm20.dot
$ dot -Tpng -o simple.png simple.dot

View the images using feh:

$ feh -Z -F sm4.png
$ feh -Z -F sm20.png
$ feh -Z -f simple.png

PDF Slides

The slides can be generated using TexMaker.

Code Slides

The code slides require bat and ksh and can be viewed by running ./code_slides.sh

Presentation Monitor Configuration

Configure secondary monitor to mirror the main monitor using xrandr:

$ xrandr --output SECONDARY --same-as PRIMARY

Where SECONDARY is the name of the second monitor and PRIMARY is the name of the primary monitor.