tox

A Rust workspace of parsing and expression evaluation crates.

// Quick example: parse and evaluate a math expression
use shunting::{ShuntingParser, MathContext};

let expr = ShuntingParser::parse_str("sin(0.2)^2 + cos(0.2)^2").unwrap();
let result = MathContext::new().eval(&expr).unwrap();
println!("{}", result);

Crates

Crate	Description
lexers	Reusable tokenizers — numbers, identifiers, math, strings, lisp, quoted text
earlgrey	Earley CFG parser — ambiguous grammars, EBNF, custom ASTs, all parse trees
kronos	Time sequence computation — "the 3rd Monday of the month", intervals, shifts
fluxcap	Natural language time parsing — "next Tuesday at 3pm", "3 weeks ago"
shunting	Math expression evaluator — operators, functions, variables, random variables
lisp	Minimal Lisp interpreter — closures, special forms, REPL
lox	C-style scripting language — variables, functions, closures, classes

Quick Examples

Parse natural language time expressions:

use fluxcap::TimeMachine;

let tm = TimeMachine::new();
let results = tm.eval("next Tuesday", None).unwrap();
for r in results {
    println!("{:?}", r);
}

Build a grammar and parse custom syntax:

use earlgrey::{ParserBuilder, EbnfParser};

let grammar = EbnfParser::new().parse(r#"
    expr := 'x' '+' 'y';
"#).unwrap();

let parser = ParserBuilder::new(grammar, "expr")
    .terminal("x", |_| Some(1))
    .terminal("y", |_| Some(2))
    .build()
    .unwrap();

for tree in parser.parse_all(&mut vec!["x", "+", "y"].into_iter()) {
    println!("{:?}", tree);
}

Compute time sequences:

use kronos::{TimeSeqSpec, TimeSpan};
use time::macros::datetime;

let reftime = datetime!(2024-06-01 12:00 UTC);
let mondays = TimeSeqSpec::weekday(1); // Monday
for day in mondays.future(reftime).take(3) {
    println!("{:?}", day);
}

Running a Crate's REPL or Binary

Most crates ship with a runnable example or binary:

cargo run -p toxtools --bin numerica  # Numerica REPL
cargo run -p toxtools --bin shunting  # Math expression REPL
cargo run -p toxtools --bin fluxcap   # Time expression parser
cargo run -p toxtools --bin lisp      # Lisp REPL
cargo run -p lox                      # Lox interpreter

See each crate's README for detailed documentation.