Yet Another Useless Language Part 10 — Parser

This is the tenth part of the YAUL series. For your convenience you can find other parts in the table of contents in Part 1 — Introduction

We have our parser almost done, there are just few things left. Let’s begin.

Program structure

For now we focused on parsing separate constructions. Now it is high time to parse the whole application:

Our application is simply a list of functions and statements. We go through the source code and collect all of them.

Error handling

We would like to be able to diagnose common parsing errors, like missing semicolon, wrong syntax, etc. This is called parser resynchronization. Here is the code:

This is just a basic error handling. In practice we would like to have better error descriptions, like what was expected in the code, but for now this is sufficient.

Missing stuff

And here is other parser’s missing stuff:


This is it when it comes to PLY’s part. Next time we are going to finish C#’s part and our language will be complete.