//! To do.

use crate::token::Token;
use crate::tokenizer::{State, Tokenizer};

/// Before a BOM.
///
/// ```text
/// > | 0xEF 0xBB 0xBF
///     ^^^^
/// ```
pub fn start(tokenizer: &mut Tokenizer) -> State {
    match tokenizer.current {
        Some(0xEF) => {
            tokenizer.enter(Token::ByteOrderMark);
            tokenizer.consume();
            State::Fn(Box::new(cont))
        }
        _ => State::Nok,
    }
}

/// Second byte in BOM.
///
/// ```text
/// > | 0xEF 0xBB 0xBF
///          ^^^^
/// ```
fn cont(tokenizer: &mut Tokenizer) -> State {
    match tokenizer.current {
        Some(0xBB) => {
            tokenizer.consume();
            State::Fn(Box::new(end))
        }
        _ => State::Nok,
    }
}

/// Last byte in BOM.
///
/// ```text
/// > | 0xEF 0xBB 0xBF
///               ^^^^
/// ```
fn end(tokenizer: &mut Tokenizer) -> State {
    match tokenizer.current {
        Some(0xBF) => {
            tokenizer.consume();
            tokenizer.exit(Token::ByteOrderMark);
            State::Ok
        }
        _ => State::Nok,
    }
}