What's everyone working on this week (20/2022)?

llogiq · May 16, 2022, 6:37am

New week, new Rust! What are you folks up to?

clinuxrulz · May 20, 2022, 3:06am

Still going with parse-bolt. And I have something rather exciting. Its becoming a parser combinator library that compiles down into an LR(1) parser.

In the grammar this means:

Direct left recursion -> No problems
Indirect left recursion -> No problems
It is deterministic -> linear time complexity with length of input. No backtracking is performed (or required) and it feed just 1 token at a time. (Blazing fast!)

It is currently done via parser3.rs while I am experimenting:

github.com

clinuxrulz/parse-bolt/blob/be041e4ea39c7c8c9442fe2de962280bc8d2a61f/src/parser3.rs

use super::TokenStream;
use std::any::Any;
use std::cell::RefCell;
use std::collections::HashMap;
use std::collections::HashSet;
use std::marker::PhantomData;
use std::rc::Rc;

pub struct Pos {
    pub offset: usize,
    pub line: usize,
    pub row: usize,
}

pub struct Span {
    pub from: Pos,
    pub to: Pos,
}

pub trait TokenClass {

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Soon I'll make it the default.

There is one optimization I need to do for the parser that gets generated. Currently it processes the result though a value stack of type Vec<Box<dyn Any>>. But if I instead use Vec<u8> and cast raw pointers into and out of the value stack, then I can match the speed of carefully crafted hand written parsers and parser generators.

flirora · May 22, 2022, 4:14am

Working on refactoring samsara, the proc macro that generates types describing paths in a finite state machine, to move its logic outside of one huge function.