Crate langen

Langen - A tool to create programming languages

use langen::{Grammar, NoErr, Span, Tokens};

#[derive(Tokens, Grammar, Debug)]
#[ignored(r"[ \t]")]
enum Math {
    #[token(r"\(")]
    LParen,

    #[token(r"\)")]
    RParen,

    #[token(r"\+")]
    Plus,

    #[token(r"-")]
    Minus,

    #[token(r"\*")]
    Mul,

    #[token(r"/")]
    Div,

    #[token(r"[0-9]+", |s: &str| {s.parse()})]
    IntLit(i32),

    #[rule(|_span: Span, expr: i32, term: i32| Ok::<i32, NoErr>(expr+term), Expression, Plus, Term)]
    #[rule(|_span: Span, expr: i32, term: i32| Ok::<i32, NoErr>(expr+term), Expression, Minus, Term)]
    #[rule(|_span: Span, term: i32| Ok::<i32, NoErr>(term), Term)]
    #[rule(|_span: Span, term: i32| Ok::<i32, NoErr>(-term), Minus, Factor)]
    Expression(i32),

    #[rule(|_span: Span, term: i32, factor: i32| Ok::<i32, NoErr>(term*factor), Term, Mul, Factor)]
    #[rule(|_span: Span, term: i32, factor: i32| Ok::<i32, NoErr>(term/factor), Term, Div, Factor)]
    #[rule(|_span: Span, factor: i32| Ok::<i32, NoErr>(factor), Factor)]
    Term(i32),

    #[rule(|_span: Span, intlit: i32| Ok::<i32, NoErr>(intlit), IntLit)]
    #[rule(|_span: Span, expr: i32| Ok::<i32, NoErr>(expr), LParen, Expression, RParen)]
    Factor(i32),
}

let input = "(33+5) * (-34)";
let tokens = Math::scan(input).unwrap();
for (t, s) in &tokens {
    println!("{}\t{:?}", s, t);
}
let result = Math::parse(tokens).unwrap();
println!("{:?}", result);

Re-exports

pub use regex_automata;

Structs

NoErr

A placeholder type that you can use in the type of process_funcs that can’t error

Span

A range of characters in the input file

Enums

LexerError

Possible runtime errors during the lexical analysis

ParserError

Possible runtime errors during the syntactical analysis

Traits

Grammar

Use the Grammar derive macro to generate a parser. See Grammar for more info.

Tokens

Use the Tokens derive macro to generate a lexer. See Tokens for more info.

Derive Macros

Grammar

Derive macro for Grammar

Tokens

Derive macro for Tokens