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// SPDX-License-Identifier: AGPL-3.0-or-later
//! Lexer implementation using logos.
use logos::{Lexer, Logos};
/// List of operator codes for the lexer
/// Note: Any input symbol that is not in this list is a comment
fn loop_callback(lex: &Lexer<Token>) -> (usize, usize) {
let span = lex.span();
(span.start, span.len())
}
/// List of Tokens for the lexer
/// Note: Any input symbol that is not in this list is a comment
#[derive(Clone, Copy, Debug, Logos, PartialEq, Eq)]
#[logos(skip r"[^<>+\-.,\[\]]+")]
pub enum Token {
/// `>`
///
/// Increment the data pointer by one (to point to the next cell to the
/// right).
#[token(">")]
IncrementPointer,
/// `<`
///
/// Decrement the data pointer by one (to point to the next cell to the
/// left).
#[token("<")]
DecrementPointer,
/// `+`
///
/// Increment the byte at the data pointer by one.
#[token("+")]
IncrementByte,
/// `-`
///
/// Decrement the byte at the data pointer by one.
#[token("-")]
DecrementByte,
/// `.`
///
/// Output the byte at the data pointer.
#[token(".")]
OutputByte,
/// `,`
///
/// Accept one byte of input, storing its value in the byte at the data
/// pointer.
#[token(",")]
InputByte,
/// `[`
///
/// If the byte at the data pointer is zero, then instead of moving the
/// instruction pointer forward to the next command, jump it forward to the
/// command after the matching ] command.
#[token("[", loop_callback)]
StartLoop((usize, usize)),
/// `]`
///
/// If the byte at the data pointer is nonzero, then instead of moving the
/// instruction pointer forward to the next command, jump it back to the
/// command after the matching [ command.
#[token("]", loop_callback)]
EndLoop((usize, usize)),
}
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