lalrpop VS pest

And some related parser tools: - https://github.com/kevinmehall/rust-peg - https://github.com/pest-parser/pest - https://github.com/lalrpop/lalrpop

lalrpop

Rust is a very nice langage for implementing compilers, and has a nice ecosystem for it (logos, rust-peg, lalrpop, astmaker -- this one is mine --, etc...).

rust-langdev has a lot of libraries for building compilers in Rust. Perhaps you could use these to make your implementation easier, and revisit it later if you want to build things from scratch. I'd suggest logos for lexing, LALRPOP / chumsky for parsing, and rust-gc for garbage collection.

Hi! For one of my projects I am currently using lalrpop (https://github.com/lalrpop/lalrpop/tree/master/doc/calculator/src), which is far from complete, but has the basic syntax I was looking for. I took some examples and worked around some lexer stuff but I’m currently happy with it. If you use it and have Intellij stuff installed, you can also use a plug-in for highlighting and SOMETIMES error checking. Otherwise, even VSCode had a great plug-in for highlighting!

How would you compare and contrast this with, say, lalrpop?

lalrpop is great. It's a completely different approach from nom, but for parsing a programming language, I would at least consider it. RustPython uses it.

I presume LALRPOP handles left recursion just fine.

I wanted to share an experimental side project I have been working on for some time. I constantly use commands like `jq` and `yq` for processing structured data in my day job and I was curious if a similar idea could be applied to images.

Another goal of mine was to get some exposure to with rust. I discovered the LALRPOP parser generator which really helped moved the project along (https://github.com/lalrpop/lalrpop)

The key point here is that we are going to depend on the lalrpop library to generate the parser based on the formal grammar we define. Note that we have it as part of the [build-dependencies] section and we only depend on a tiny utility crate called lalrpop-util at runtime. The reason for that is the main lalrpop "magic" would happen during the crate compilation (in the build.rs file) when lalrpop would generate the deterministic pushdown automaton based on our grammar. The code generation logic is not required to be part of our interpreter, we only need a few utility methods from the lalrpop-util for the automaton to operate. You might have noticed that we also enable the lexer feature of lalrpop, because we are going to use lexer provided by lalrpop as well (please refer to the Part I if you do not know what the lexer is).

Would definitely be interesting, but from a cursory look at the repository, it doesn't look like squeezing the last percentage points of performance has been a priority yet.

Things that stand out:

- The `awk` implementation uses the Pest parser generator (https://pest.rs/), which is known to not generate the fastest possible parsers, but is great for getting up and running.

- They are using the `clap` crate for argument parsing, which is also known to not be the fastest, but again is very user friendly (for example, it does Unicode linebreaks in the output of `--help`). It's marginal, but for a tiny utility being invoked many times from a shell script, this can add up.

It's very probably "fast enough", and it makes sense to prioritize like this at this point, but people shouldn't use this expecting a performance improvement right now.

Nice work. Out of curiosity, did you consider using pest (https://pest.rs/) to help build your parser? Or is it too much for what you are doing?

And some related parser tools: - https://github.com/kevinmehall/rust-peg - https://github.com/pest-parser/pest - https://github.com/lalrpop/lalrpop

I had recently completed the first year of my Computer Science class at school and will begin my second year soon. My schools' class forces the use of Java programming language, and I absolutely hated it. So, over the course of a little less than a month, I wrote my own programming language, in Rust (objectively best programming language), using pest, to be as similar to Rust as possible, but compiling to Java.

I second pest.rs. Using it is fairly intuitive and there's also a live playground on their website which is great for quickly developing and testing your AST (abstract syntax tree) parser for whatever language you're implementing.

This is where you'll run into trouble. People who write parsing-related Rust crates generally write things like pest that expect their syntax to be defined completely at compile time so the parser can be run through the compiler's optimizers for best performance.

Give https://pest.rs a try.

For now I have used pest to generate an AST that borrows from the given input. But if I can manage to make the parser generic over the return type it may be worth a refactoring.