This repository contains a simple interpreter for algebraic expressions, built to demonstrate some core compiler concepts. This is a companion to the blog post I wrote on Compilers. The entire codebase is just over 300 lines.
This interpreter is capable of parsing expressions including any combination of the 4 basic mathematic operators (+, -, *, /), and assignments to variables. Operands for the operators may only be integer values or variable references. For example, the following is a valid program:
@a = 2 + 2
@b = 1 + 3 * 3
@c = b / a
For simplicity, running a program will print out the stack contents and the symbol table after execution. For the above, this would appear as:
Stack contents: []
Variables:
a = 4
b = 10
c = 2.5
You will need Crystal installed, which can easily be done on the command line. Installing with brew is as simple as running brew install:
brew install crystal-langInstalling on linux depends on your distribution, so check the installation guide for more information.
With Crystal installed, getting this project installed is as simple as a git clone:
git clone https://github.com/faultyserver/compilers-introWith the project installed locally, running the interpreter is as simple as running crystal run:
crystal run src/runner.crYou can also build a standalone binary to run at anytime with crystal build:
crystal build src/runner.cr
# Then later on, run it
./runnerTo change the input to the interpreter, edit the string passed to Parser.new in runner.cr, then rerun/rebuild.
I don't expect this repository to change much, as it is just demonstrating initial concepts.
- Fork it ( https://github.com/faultyserver/compilers-intro/fork )
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create a new Pull Request
- faultyserver Jon Egeland - creator, maintainer