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//! This file defines the behaviour of the Atomic languages, and
//! provides a default implementation.
//!
//! Here I do not to substitute external packages' implementations in
//! the future, so why define a trait for the atomic languages?
//! Because this way I can easily substitute other implementations if
//! I have better ideas in the future.
use grammar::{Error as GrammarError, TNT};
use nfa::{DOption, Nfa};
/// The expected behaviours of an atomic language.
pub trait Atom: Nfa<DOption<TNT>> {
/// Return the index of a node representing the derivative of the
/// left-linear null closure of `nt` with respect to `t`.
fn atom(&self, nt: usize, t: usize) -> Result<Option<usize>, GrammarError>;
/// Return the index of the empty state.
fn empty(&self) -> usize;
}
pub mod default;
pub use default::DefaultAtom;
#[cfg(test)]
mod tests {
use super::*;
use grammar::test_grammar_helper::*;
#[test]
fn atom() -> Result<(), Box<dyn std::error::Error>> {
let grammar = new_notes_grammar()?;
let atom = DefaultAtom::from_grammar(grammar)?;
println!("atom = {atom}");
Ok(())
}
}
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