crates/winnow/src/binary/bits/mod.rs - platform/external/rust/android-crates-io - Git at Google

 //! Bit level parsers
 //!

 #[cfg(test)]
 mod tests;

 use crate::combinator::trace;
 use crate::error::{ErrMode, ErrorConvert, ErrorKind, Needed, ParserError};
 use crate::lib::std::ops::{AddAssign, Div, Shl, Shr};
 use crate::stream::{AsBytes, Stream, StreamIsPartial, ToUsize};
 use crate::{unpeek, IResult, PResult, Parser};

 /// Number of bits in a byte
 const BYTE: usize = u8::BITS as usize;

 /// Converts a byte-level input to a bit-level input
 ///
 /// See [`bytes`] to convert it back.
 ///
 /// # Example
 /// ```
 /// use winnow::prelude::*;
 /// use winnow::Bytes;
 /// use winnow::binary::bits::{bits, take};
 /// use winnow::error::InputError;
 ///
 /// type Stream<'i> = &'i Bytes;
 ///
 /// fn stream(b: &[u8]) -> Stream<'_> {
 ///     Bytes::new(b)
 /// }
 ///
 /// fn parse(input: Stream<'_>) -> IResult<Stream<'_>, (u8, u8)> {
 ///     bits::<_, _, InputError<(_, usize)>, _, _>((take(4usize), take(8usize))).parse_peek(input)
 /// }
 ///
 /// let input = stream(&[0x12, 0x34, 0xff, 0xff]);
 ///
 /// let output = parse(input).expect("We take 1.5 bytes and the input is longer than 2 bytes");
 ///
 /// // The first byte is consumed, the second byte is partially consumed and dropped.
 /// let remaining = output.0;
 /// assert_eq!(remaining, stream(&[0xff, 0xff]));
 ///
 /// let parsed = output.1;
 /// assert_eq!(parsed.0, 0x01);
 /// assert_eq!(parsed.1, 0x23);
 /// ```
 pub fn bits<I, O, E1, E2, P>(mut parser: P) -> impl Parser<I, O, E2>
 where
     E1: ParserError<(I, usize)> + ErrorConvert<E2>,
     E2: ParserError<I>,
     I: Stream + Clone,
     P: Parser<(I, usize), O, E1>,
 {
     trace(
         "bits",
         unpeek(move |input: I| {
             match parser.parse_peek((input, 0)) {
                 Ok(((rest, offset), result)) => {
                     // If the next byte has been partially read, it will be sliced away as well.
                     // The parser functions might already slice away all fully read bytes.
                     // That's why `offset / BYTE` isn't necessarily needed at all times.
                     let remaining_bytes_index =
                         offset / BYTE + if offset % BYTE == 0 { 0 } else { 1 };
                     let (input, _) = rest.peek_slice(remaining_bytes_index);
                     Ok((input, result))
                 }
                 Err(ErrMode::Incomplete(n)) => {
                     Err(ErrMode::Incomplete(n.map(|u| u.get() / BYTE + 1)))
                 }
                 Err(e) => Err(e.convert()),
             }
         }),
     )
 }

 /// Convert a [`bits`] stream back into a byte stream
 ///
 /// **Warning:** A partial byte remaining in the input will be ignored and the given parser will
 /// start parsing at the next full byte.
 ///
 /// ```
 /// use winnow::prelude::*;
 /// use winnow::Bytes;
 /// use winnow::binary::bits::{bits, bytes, take};
 /// use winnow::combinator::rest;
 /// use winnow::error::InputError;
 ///
 /// type Stream<'i> = &'i Bytes;
 ///
 /// fn stream(b: &[u8]) -> Stream<'_> {
 ///     Bytes::new(b)
 /// }
 ///
 /// fn parse(input: Stream<'_>) -> IResult<Stream<'_>, (u8, u8, &[u8])> {
 ///   bits::<_, _, InputError<(_, usize)>, _, _>((
 ///     take(4usize),
 ///     take(8usize),
 ///     bytes::<_, _, InputError<_>, _, _>(rest)
 ///   )).parse_peek(input)
 /// }
 ///
 /// let input = stream(&[0x12, 0x34, 0xff, 0xff]);
 ///
 /// assert_eq!(parse(input), Ok(( stream(&[]), (0x01, 0x23, &[0xff, 0xff][..]) )));
 /// ```
 pub fn bytes<I, O, E1, E2, P>(mut parser: P) -> impl Parser<(I, usize), O, E2>
 where
     E1: ParserError<I> + ErrorConvert<E2>,
     E2: ParserError<(I, usize)>,
     I: Stream<Token = u8> + Clone,
     P: Parser<I, O, E1>,
 {
     trace(
         "bytes",
         unpeek(move |(input, offset): (I, usize)| {
             let (inner, _) = if offset % BYTE != 0 {
                 input.peek_slice(1 + offset / BYTE)
             } else {
                 input.peek_slice(offset / BYTE)
             };
             let i = (input, offset);
             match parser.parse_peek(inner) {
                 Ok((rest, res)) => Ok(((rest, 0), res)),
                 Err(ErrMode::Incomplete(Needed::Unknown)) => {
                     Err(ErrMode::Incomplete(Needed::Unknown))
                 }
                 Err(ErrMode::Incomplete(Needed::Size(sz))) => {
                     Err(match sz.get().checked_mul(BYTE) {
                         Some(v) => ErrMode::Incomplete(Needed::new(v)),
                         None => ErrMode::Cut(E2::assert(
                             &i,
                             "overflow in turning needed bytes into needed bits",
                         )),
                     })
                 }
                 Err(e) => Err(e.convert()),
             }
         }),
     )
 }

 /// Parse taking `count` bits
 ///
 /// # Example
 /// ```rust
 /// # use winnow::prelude::*;
 /// # use winnow::Bytes;
 /// # use winnow::error::{InputError, ErrorKind};
 /// use winnow::binary::bits::take;
 ///
 /// type Stream<'i> = &'i Bytes;
 ///
 /// fn stream(b: &[u8]) -> Stream<'_> {
 ///     Bytes::new(b)
 /// }
 ///
 /// fn parser(input: (Stream<'_>, usize), count: usize)-> IResult<(Stream<'_>, usize), u8> {
 ///   take(count).parse_peek(input)
 /// }
 ///
 /// // Consumes 0 bits, returns 0
 /// assert_eq!(parser((stream(&[0b00010010]), 0), 0), Ok(((stream(&[0b00010010]), 0), 0)));
 ///
 /// // Consumes 4 bits, returns their values and increase offset to 4
 /// assert_eq!(parser((stream(&[0b00010010]), 0), 4), Ok(((stream(&[0b00010010]), 4), 0b00000001)));
 ///
 /// // Consumes 4 bits, offset is 4, returns their values and increase offset to 0 of next byte
 /// assert_eq!(parser((stream(&[0b00010010]), 4), 4), Ok(((stream(&[]), 0), 0b00000010)));
 ///
 /// // Tries to consume 12 bits but only 8 are available
 /// assert_eq!(parser((stream(&[0b00010010]), 0), 12), Err(winnow::error::ErrMode::Backtrack(InputError::new((stream(&[0b00010010]), 0), ErrorKind::Eof))));
 /// ```
 #[inline(always)]
 pub fn take<I, O, C, E: ParserError<(I, usize)>>(count: C) -> impl Parser<(I, usize), O, E>
 where
     I: Stream<Token = u8> + AsBytes + StreamIsPartial + Clone,
     C: ToUsize,
     O: From<u8> + AddAssign + Shl<usize, Output = O> + Shr<usize, Output = O>,
 {
     let count = count.to_usize();
     trace(
         "take",
         unpeek(move |input: (I, usize)| {
             if <I as StreamIsPartial>::is_partial_supported() {
                 take_::<_, _, _, true>(input, count)
             } else {
                 take_::<_, _, _, false>(input, count)
             }
         }),
     )
 }

 fn take_<I, O, E: ParserError<(I, usize)>, const PARTIAL: bool>(
     (input, bit_offset): (I, usize),
     count: usize,
 ) -> IResult<(I, usize), O, E>
 where
     I: StreamIsPartial,
     I: Stream<Token = u8> + AsBytes + Clone,
     O: From<u8> + AddAssign + Shl<usize, Output = O> + Shr<usize, Output = O>,
 {
     if count == 0 {
         Ok(((input, bit_offset), 0u8.into()))
     } else {
         if input.eof_offset() * BYTE < count + bit_offset {
             if PARTIAL && input.is_partial() {
                 Err(ErrMode::Incomplete(Needed::new(count)))
             } else {
                 Err(ErrMode::from_error_kind(
                     &(input, bit_offset),
                     ErrorKind::Eof,
                 ))
             }
         } else {
             let cnt = (count + bit_offset).div(BYTE);
             let mut acc: O = 0_u8.into();
             let mut offset: usize = bit_offset;
             let mut remaining: usize = count;
             let mut end_offset: usize = 0;

             for byte in input.as_bytes().iter().copied().take(cnt + 1) {
                 if remaining == 0 {
                     break;
                 }
                 let val: O = if offset == 0 {
                     byte.into()
                 } else {
                     (byte << offset >> offset).into()
                 };

                 if remaining < BYTE - offset {
                     acc += val >> (BYTE - offset - remaining);
                     end_offset = remaining + offset;
                     break;
                 } else {
                     acc += val << (remaining - (BYTE - offset));
                     remaining -= BYTE - offset;
                     offset = 0;
                 }
             }
             let (input, _) = input.peek_slice(cnt);
             Ok(((input, end_offset), acc))
         }
     }
 }

 /// Parse taking `count` bits and comparing them to `pattern`
 ///
 /// # Example
 ///
 /// ```rust
 /// # use winnow::prelude::*;
 /// # use winnow::Bytes;
 /// # use winnow::error::{InputError, ErrorKind};
 /// use winnow::binary::bits::tag;
 ///
 /// type Stream<'i> = &'i Bytes;
 ///
 /// fn stream(b: &[u8]) -> Stream<'_> {
 ///     Bytes::new(b)
 /// }
 ///
 /// /// Compare the lowest `count` bits of `input` against the lowest `count` bits of `pattern`.
 /// /// Return Ok and the matching section of `input` if there's a match.
 /// /// Return Err if there's no match.
 /// fn parser(pattern: u8, count: u8, input: (Stream<'_>, usize)) -> IResult<(Stream<'_>, usize), u8> {
 ///     tag(pattern, count).parse_peek(input)
 /// }
 ///
 /// // The lowest 4 bits of 0b00001111 match the lowest 4 bits of 0b11111111.
 /// assert_eq!(
 ///     parser(0b0000_1111, 4, (stream(&[0b1111_1111]), 0)),
 ///     Ok(((stream(&[0b1111_1111]), 4), 0b0000_1111))
 /// );
 ///
 /// // The lowest bit of 0b00001111 matches the lowest bit of 0b11111111 (both are 1).
 /// assert_eq!(
 ///     parser(0b00000001, 1, (stream(&[0b11111111]), 0)),
 ///     Ok(((stream(&[0b11111111]), 1), 0b00000001))
 /// );
 ///
 /// // The lowest 2 bits of 0b11111111 and 0b00000001 are different.
 /// assert_eq!(
 ///     parser(0b000000_01, 2, (stream(&[0b111111_11]), 0)),
 ///     Err(winnow::error::ErrMode::Backtrack(InputError::new(
 ///         (stream(&[0b11111111]), 0),
 ///         ErrorKind::Tag
 ///     )))
 /// );
 ///
 /// // The lowest 8 bits of 0b11111111 and 0b11111110 are different.
 /// assert_eq!(
 ///     parser(0b11111110, 8, (stream(&[0b11111111]), 0)),
 ///     Err(winnow::error::ErrMode::Backtrack(InputError::new(
 ///         (stream(&[0b11111111]), 0),
 ///         ErrorKind::Tag
 ///     )))
 /// );
 /// ```
 #[inline(always)]
 #[doc(alias = "literal")]
 #[doc(alias = "just")]
 pub fn tag<I, O, C, E: ParserError<(I, usize)>>(
     pattern: O,
     count: C,
 ) -> impl Parser<(I, usize), O, E>
 where
     I: Stream<Token = u8> + AsBytes + StreamIsPartial + Clone,
     C: ToUsize,
     O: From<u8> + AddAssign + Shl<usize, Output = O> + Shr<usize, Output = O> + PartialEq,
 {
     let count = count.to_usize();
     trace("tag", move |input: &mut (I, usize)| {
         let start = input.checkpoint();

         take(count).parse_next(input).and_then(|o| {
             if pattern == o {
                 Ok(o)
             } else {
                 input.reset(start);
                 Err(ErrMode::Backtrack(E::from_error_kind(
                     input,
                     ErrorKind::Tag,
                 )))
             }
         })
     })
 }

 /// Parses one specific bit as a bool.
 ///
 /// # Example
 ///
 /// ```rust
 /// # use winnow::prelude::*;
 /// # use winnow::Bytes;
 /// # use winnow::error::{InputError, ErrorKind};
 /// use winnow::binary::bits::bool;
 ///
 /// type Stream<'i> = &'i Bytes;
 ///
 /// fn stream(b: &[u8]) -> Stream<'_> {
 ///     Bytes::new(b)
 /// }
 ///
 /// fn parse(input: (Stream<'_>, usize)) -> IResult<(Stream<'_>, usize), bool> {
 ///     bool.parse_peek(input)
 /// }
 ///
 /// assert_eq!(parse((stream(&[0b10000000]), 0)), Ok(((stream(&[0b10000000]), 1), true)));
 /// assert_eq!(parse((stream(&[0b10000000]), 1)), Ok(((stream(&[0b10000000]), 2), false)));
 /// ```
 #[doc(alias = "any")]
 pub fn bool<I, E: ParserError<(I, usize)>>(input: &mut (I, usize)) -> PResult<bool, E>
 where
     I: Stream<Token = u8> + AsBytes + StreamIsPartial + Clone,
 {
     trace("bool", |input: &mut (I, usize)| {
         let bit: u32 = take(1usize).parse_next(input)?;
         Ok(bit != 0)
     })
     .parse_next(input)
 }
	//! Bit level parsers
	//!

	#[cfg(test)]
	mod tests;

	use crate::combinator::trace;
	use crate::error::{ErrMode, ErrorConvert, ErrorKind, Needed, ParserError};
	use crate::lib::std::ops::{AddAssign, Div, Shl, Shr};
	use crate::stream::{AsBytes, Stream, StreamIsPartial, ToUsize};
	use crate::{unpeek, IResult, PResult, Parser};

	/// Number of bits in a byte
	const BYTE: usize = u8::BITS as usize;

	/// Converts a byte-level input to a bit-level input
	///
	/// See [`bytes`] to convert it back.
	///
	/// # Example
	/// ```
	/// use winnow::prelude::*;
	/// use winnow::Bytes;
	/// use winnow::binary::bits::{bits, take};
	/// use winnow::error::InputError;
	///
	/// type Stream<'i> = &'i Bytes;
	///
	/// fn stream(b: &[u8]) -> Stream<'_> {
	/// Bytes::new(b)
	/// }
	///
	/// fn parse(input: Stream<'_>) -> IResult<Stream<'_>, (u8, u8)> {
	/// bits::<_, _, InputError<(_, usize)>, _, _>((take(4usize), take(8usize))).parse_peek(input)
	/// }
	///
	/// let input = stream(&[0x12, 0x34, 0xff, 0xff]);
	///
	/// let output = parse(input).expect("We take 1.5 bytes and the input is longer than 2 bytes");
	///
	/// // The first byte is consumed, the second byte is partially consumed and dropped.
	/// let remaining = output.0;
	/// assert_eq!(remaining, stream(&[0xff, 0xff]));
	///
	/// let parsed = output.1;
	/// assert_eq!(parsed.0, 0x01);
	/// assert_eq!(parsed.1, 0x23);
	/// ```
	pub fn bits<I, O, E1, E2, P>(mut parser: P) -> impl Parser<I, O, E2>
	where
	E1: ParserError<(I, usize)> + ErrorConvert<E2>,
	E2: ParserError<I>,
	I: Stream + Clone,
	P: Parser<(I, usize), O, E1>,
	{
	trace(
	"bits",
	unpeek(move \|input: I\| {
	match parser.parse_peek((input, 0)) {
	Ok(((rest, offset), result)) => {
	// If the next byte has been partially read, it will be sliced away as well.
	// The parser functions might already slice away all fully read bytes.
	// That's why `offset / BYTE` isn't necessarily needed at all times.
	let remaining_bytes_index =
	offset / BYTE + if offset % BYTE == 0 { 0 } else { 1 };
	let (input, _) = rest.peek_slice(remaining_bytes_index);
	Ok((input, result))
	}
	Err(ErrMode::Incomplete(n)) => {
	Err(ErrMode::Incomplete(n.map(\|u\| u.get() / BYTE + 1)))
	}
	Err(e) => Err(e.convert()),
	}
	}),
	)
	}

	/// Convert a [`bits`] stream back into a byte stream
	///
	/// Warning: A partial byte remaining in the input will be ignored and the given parser will
	/// start parsing at the next full byte.
	///
	/// ```
	/// use winnow::prelude::*;
	/// use winnow::Bytes;
	/// use winnow::binary::bits::{bits, bytes, take};
	/// use winnow::combinator::rest;
	/// use winnow::error::InputError;
	///
	/// type Stream<'i> = &'i Bytes;
	///
	/// fn stream(b: &[u8]) -> Stream<'_> {
	/// Bytes::new(b)
	/// }
	///
	/// fn parse(input: Stream<'_>) -> IResult<Stream<'_>, (u8, u8, &[u8])> {
	/// bits::<_, _, InputError<(_, usize)>, _, _>((
	/// take(4usize),
	/// take(8usize),
	/// bytes::<_, _, InputError<_>, _, _>(rest)
	/// )).parse_peek(input)
	/// }
	///
	/// let input = stream(&[0x12, 0x34, 0xff, 0xff]);
	///
	/// assert_eq!(parse(input), Ok(( stream(&[]), (0x01, 0x23, &[0xff, 0xff][..]) )));
	/// ```
	pub fn bytes<I, O, E1, E2, P>(mut parser: P) -> impl Parser<(I, usize), O, E2>
	where
	E1: ParserError<I> + ErrorConvert<E2>,
	E2: ParserError<(I, usize)>,
	I: Stream<Token = u8> + Clone,
	P: Parser<I, O, E1>,
	{
	trace(
	"bytes",
	unpeek(move \|(input, offset): (I, usize)\| {
	let (inner, _) = if offset % BYTE != 0 {
	input.peek_slice(1 + offset / BYTE)
	} else {
	input.peek_slice(offset / BYTE)
	};
	let i = (input, offset);
	match parser.parse_peek(inner) {
	Ok((rest, res)) => Ok(((rest, 0), res)),
	Err(ErrMode::Incomplete(Needed::Unknown)) => {
	Err(ErrMode::Incomplete(Needed::Unknown))
	}
	Err(ErrMode::Incomplete(Needed::Size(sz))) => {
	Err(match sz.get().checked_mul(BYTE) {
	Some(v) => ErrMode::Incomplete(Needed::new(v)),
	None => ErrMode::Cut(E2::assert(
	&i,
	"overflow in turning needed bytes into needed bits",
	)),
	})
	}
	Err(e) => Err(e.convert()),
	}
	}),
	)
	}

	/// Parse taking `count` bits
	///
	/// # Example
	/// ```rust
	/// # use winnow::prelude::*;
	/// # use winnow::Bytes;
	/// # use winnow::error::{InputError, ErrorKind};
	/// use winnow::binary::bits::take;
	///
	/// type Stream<'i> = &'i Bytes;
	///
	/// fn stream(b: &[u8]) -> Stream<'_> {
	/// Bytes::new(b)
	/// }
	///
	/// fn parser(input: (Stream<'_>, usize), count: usize)-> IResult<(Stream<'_>, usize), u8> {
	/// take(count).parse_peek(input)
	/// }
	///
	/// // Consumes 0 bits, returns 0
	/// assert_eq!(parser((stream(&[0b00010010]), 0), 0), Ok(((stream(&[0b00010010]), 0), 0)));
	///
	/// // Consumes 4 bits, returns their values and increase offset to 4
	/// assert_eq!(parser((stream(&[0b00010010]), 0), 4), Ok(((stream(&[0b00010010]), 4), 0b00000001)));
	///
	/// // Consumes 4 bits, offset is 4, returns their values and increase offset to 0 of next byte
	/// assert_eq!(parser((stream(&[0b00010010]), 4), 4), Ok(((stream(&[]), 0), 0b00000010)));
	///
	/// // Tries to consume 12 bits but only 8 are available
	/// assert_eq!(parser((stream(&[0b00010010]), 0), 12), Err(winnow::error::ErrMode::Backtrack(InputError::new((stream(&[0b00010010]), 0), ErrorKind::Eof))));
	/// ```
	#[inline(always)]
	pub fn take<I, O, C, E: ParserError<(I, usize)>>(count: C) -> impl Parser<(I, usize), O, E>
	where
	I: Stream<Token = u8> + AsBytes + StreamIsPartial + Clone,
	C: ToUsize,
	O: From<u8> + AddAssign + Shl<usize, Output = O> + Shr<usize, Output = O>,
	{
	let count = count.to_usize();
	trace(
	"take",
	unpeek(move \|input: (I, usize)\| {
	if <I as StreamIsPartial>::is_partial_supported() {
	take_::<_, _, _, true>(input, count)
	} else {
	take_::<_, _, _, false>(input, count)
	}
	}),
	)
	}

	fn take_<I, O, E: ParserError<(I, usize)>, const PARTIAL: bool>(
	(input, bit_offset): (I, usize),
	count: usize,
	) -> IResult<(I, usize), O, E>
	where
	I: StreamIsPartial,
	I: Stream<Token = u8> + AsBytes + Clone,
	O: From<u8> + AddAssign + Shl<usize, Output = O> + Shr<usize, Output = O>,
	{
	if count == 0 {
	Ok(((input, bit_offset), 0u8.into()))
	} else {
	if input.eof_offset() * BYTE < count + bit_offset {
	if PARTIAL && input.is_partial() {
	Err(ErrMode::Incomplete(Needed::new(count)))
	} else {
	Err(ErrMode::from_error_kind(
	&(input, bit_offset),
	ErrorKind::Eof,
	))
	}
	} else {
	let cnt = (count + bit_offset).div(BYTE);
	let mut acc: O = 0_u8.into();
	let mut offset: usize = bit_offset;
	let mut remaining: usize = count;
	let mut end_offset: usize = 0;

	for byte in input.as_bytes().iter().copied().take(cnt + 1) {
	if remaining == 0 {
	break;
	}
	let val: O = if offset == 0 {
	byte.into()
	} else {
	(byte << offset >> offset).into()
	};

	if remaining < BYTE - offset {
	acc += val >> (BYTE - offset - remaining);
	end_offset = remaining + offset;
	break;
	} else {
	acc += val << (remaining - (BYTE - offset));
	remaining -= BYTE - offset;
	offset = 0;
	}
	}
	let (input, _) = input.peek_slice(cnt);
	Ok(((input, end_offset), acc))
	}
	}
	}

	/// Parse taking `count` bits and comparing them to `pattern`
	///
	/// # Example
	///
	/// ```rust
	/// # use winnow::prelude::*;
	/// # use winnow::Bytes;
	/// # use winnow::error::{InputError, ErrorKind};
	/// use winnow::binary::bits::tag;
	///
	/// type Stream<'i> = &'i Bytes;
	///
	/// fn stream(b: &[u8]) -> Stream<'_> {
	/// Bytes::new(b)
	/// }
	///
	/// /// Compare the lowest `count` bits of `input` against the lowest `count` bits of `pattern`.
	/// /// Return Ok and the matching section of `input` if there's a match.
	/// /// Return Err if there's no match.
	/// fn parser(pattern: u8, count: u8, input: (Stream<'_>, usize)) -> IResult<(Stream<'_>, usize), u8> {
	/// tag(pattern, count).parse_peek(input)
	/// }
	///
	/// // The lowest 4 bits of 0b00001111 match the lowest 4 bits of 0b11111111.
	/// assert_eq!(
	/// parser(0b0000_1111, 4, (stream(&[0b1111_1111]), 0)),
	/// Ok(((stream(&[0b1111_1111]), 4), 0b0000_1111))
	/// );
	///
	/// // The lowest bit of 0b00001111 matches the lowest bit of 0b11111111 (both are 1).
	/// assert_eq!(
	/// parser(0b00000001, 1, (stream(&[0b11111111]), 0)),
	/// Ok(((stream(&[0b11111111]), 1), 0b00000001))
	/// );
	///
	/// // The lowest 2 bits of 0b11111111 and 0b00000001 are different.
	/// assert_eq!(
	/// parser(0b000000_01, 2, (stream(&[0b111111_11]), 0)),
	/// Err(winnow::error::ErrMode::Backtrack(InputError::new(
	/// (stream(&[0b11111111]), 0),
	/// ErrorKind::Tag
	/// )))
	/// );
	///
	/// // The lowest 8 bits of 0b11111111 and 0b11111110 are different.
	/// assert_eq!(
	/// parser(0b11111110, 8, (stream(&[0b11111111]), 0)),
	/// Err(winnow::error::ErrMode::Backtrack(InputError::new(
	/// (stream(&[0b11111111]), 0),
	/// ErrorKind::Tag
	/// )))
	/// );
	/// ```
	#[inline(always)]
	#[doc(alias = "literal")]
	#[doc(alias = "just")]
	pub fn tag<I, O, C, E: ParserError<(I, usize)>>(
	pattern: O,
	count: C,
	) -> impl Parser<(I, usize), O, E>
	where
	I: Stream<Token = u8> + AsBytes + StreamIsPartial + Clone,
	C: ToUsize,
	O: From<u8> + AddAssign + Shl<usize, Output = O> + Shr<usize, Output = O> + PartialEq,
	{
	let count = count.to_usize();
	trace("tag", move \|input: &mut (I, usize)\| {
	let start = input.checkpoint();

	take(count).parse_next(input).and_then(\|o\| {
	if pattern == o {
	Ok(o)
	} else {
	input.reset(start);
	Err(ErrMode::Backtrack(E::from_error_kind(
	input,
	ErrorKind::Tag,
	)))
	}
	})
	})
	}

	/// Parses one specific bit as a bool.
	///
	/// # Example
	///
	/// ```rust
	/// # use winnow::prelude::*;
	/// # use winnow::Bytes;
	/// # use winnow::error::{InputError, ErrorKind};
	/// use winnow::binary::bits::bool;
	///
	/// type Stream<'i> = &'i Bytes;
	///
	/// fn stream(b: &[u8]) -> Stream<'_> {
	/// Bytes::new(b)
	/// }
	///
	/// fn parse(input: (Stream<'_>, usize)) -> IResult<(Stream<'_>, usize), bool> {
	/// bool.parse_peek(input)
	/// }
	///
	/// assert_eq!(parse((stream(&[0b10000000]), 0)), Ok(((stream(&[0b10000000]), 1), true)));
	/// assert_eq!(parse((stream(&[0b10000000]), 1)), Ok(((stream(&[0b10000000]), 2), false)));
	/// ```
	#[doc(alias = "any")]
	pub fn bool<I, E: ParserError<(I, usize)>>(input: &mut (I, usize)) -> PResult<bool, E>
	where
	I: Stream<Token = u8> + AsBytes + StreamIsPartial + Clone,
	{
	trace("bool", \|input: &mut (I, usize)\| {
	let bit: u32 = take(1usize).parse_next(input)?;
	Ok(bit != 0)
	})
	.parse_next(input)
	}