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//! Byte order mark occurs at the start of the document.
//!
//! It’s the three bytes 0xEF, 0xBB, and 0xBF.
//!
//! ## Tokens
//!
//! * [`ByteOrderMark`][Token::ByteOrderMark]
//!
//! ## References
//!
//! * [`micromark/lib/preprocess.js` in `micromark`](https://github.com/micromark/micromark/blob/ed23453/packages/micromark/dev/lib/preprocess.js#L54-L60)
use crate::token::Token;
use crate::tokenizer::{State, Tokenizer};
/// Before a BOM.
///
/// ```text
/// > | 0xEF 0xBB 0xBF
/// ^^^^
/// ```
pub fn start(tokenizer: &mut Tokenizer) -> State {
if tokenizer.current == Some(0xEF) {
tokenizer.enter(Token::ByteOrderMark);
tokenizer.consume();
State::Fn(Box::new(cont))
} else {
State::Nok
}
}
/// Second byte in BOM.
///
/// ```text
/// > | 0xEF 0xBB 0xBF
/// ^^^^
/// ```
fn cont(tokenizer: &mut Tokenizer) -> State {
if tokenizer.current == Some(0xBB) {
tokenizer.consume();
State::Fn(Box::new(end))
} else {
State::Nok
}
}
/// Last byte in BOM.
///
/// ```text
/// > | 0xEF 0xBB 0xBF
/// ^^^^
/// ```
fn end(tokenizer: &mut Tokenizer) -> State {
if tokenizer.current == Some(0xBF) {
tokenizer.consume();
tokenizer.exit(Token::ByteOrderMark);
State::Ok
} else {
State::Nok
}
}
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