1 files changed, 179 insertions, 0 deletions
diff --git a/third_party/rust/nom/src/bits/mod.rs b/third_party/rust/nom/src/bits/mod.rs
new file mode 100644
index 0000000000..0d3f73db25
--- /dev/null
+++ b/third_party/rust/nom/src/bits/mod.rs
@@ -0,0 +1,179 @@
+//! Bit level parsers
+//!
+
+pub mod complete;
+pub mod streaming;
+
+use crate::error::{ErrorKind, ParseError};
+use crate::internal::{Err, IResult, Needed, Parser};
+use crate::lib::std::ops::RangeFrom;
+use crate::traits::{ErrorConvert, Slice};
+
+/// Converts a byte-level input to a bit-level input, for consumption by a parser that uses bits.
+///
+/// Afterwards, the input is converted back to a byte-level parser, with any remaining bits thrown
+/// away.
+///
+/// # Example
+/// ```
+/// use nom::bits::{bits, streaming::take};
+/// use nom::error::Error;
+/// use nom::sequence::tuple;
+/// use nom::IResult;
+///
+/// fn parse(input: &[u8]) -> IResult<&[u8], (u8, u8)> {
+///     bits::<_, _, Error<(&[u8], usize)>, _, _>(tuple((take(4usize), take(8usize))))(input)
+/// }
+///
+/// let input = &[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, [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 FnMut(I) -> IResult<I, O, E2>
+where
+  E1: ParseError<(I, usize)> + ErrorConvert<E2>,
+  E2: ParseError<I>,
+  I: Slice<RangeFrom<usize>>,
+  P: Parser<(I, usize), O, E1>,
+{
+  move |input: I| match parser.parse((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 / 8` isn't necessarily needed at all times.
+      let remaining_bytes_index = offset / 8 + if offset % 8 == 0 { 0 } else { 1 };
+      Ok((rest.slice(remaining_bytes_index..), result))
+    }
+    Err(Err::Incomplete(n)) => Err(Err::Incomplete(n.map(|u| u.get() / 8 + 1))),
+    Err(Err::Error(e)) => Err(Err::Error(e.convert())),
+    Err(Err::Failure(e)) => Err(Err::Failure(e.convert())),
+  }
+}
+
+/// Counterpart to `bits`, `bytes` transforms its bit stream input into a byte slice for the underlying
+/// parser, allowing byte-slice parsers to work on bit streams.
+///
+/// A partial byte remaining in the input will be ignored and the given parser will start parsing
+/// at the next full byte.
+///
+/// ```
+/// use nom::bits::{bits, bytes, streaming::take};
+/// use nom::combinator::rest;
+/// use nom::error::Error;
+/// use nom::sequence::tuple;
+/// use nom::IResult;
+///
+/// fn parse(input: &[u8]) -> IResult<&[u8], (u8, u8, &[u8])> {
+///   bits::<_, _, Error<(&[u8], usize)>, _, _>(tuple((
+///     take(4usize),
+///     take(8usize),
+///     bytes::<_, _, Error<&[u8]>, _, _>(rest)
+///   )))(input)
+/// }
+///
+/// let input = &[0x12, 0x34, 0xff, 0xff];
+///
+/// assert_eq!(parse( input ), Ok(( &[][..], (0x01, 0x23, &[0xff, 0xff][..]) )));
+/// ```
+pub fn bytes<I, O, E1, E2, P>(mut parser: P) -> impl FnMut((I, usize)) -> IResult<(I, usize), O, E2>
+where
+  E1: ParseError<I> + ErrorConvert<E2>,
+  E2: ParseError<(I, usize)>,
+  I: Slice<RangeFrom<usize>> + Clone,
+  P: Parser<I, O, E1>,
+{
+  move |(input, offset): (I, usize)| {
+    let inner = if offset % 8 != 0 {
+      input.slice((1 + offset / 8)..)
+    } else {
+      input.slice((offset / 8)..)
+    };
+    let i = (input, offset);
+    match parser.parse(inner) {
+      Ok((rest, res)) => Ok(((rest, 0), res)),
+      Err(Err::Incomplete(Needed::Unknown)) => Err(Err::Incomplete(Needed::Unknown)),
+      Err(Err::Incomplete(Needed::Size(sz))) => Err(match sz.get().checked_mul(8) {
+        Some(v) => Err::Incomplete(Needed::new(v)),
+        None => Err::Failure(E2::from_error_kind(i, ErrorKind::TooLarge)),
+      }),
+      Err(Err::Error(e)) => Err(Err::Error(e.convert())),
+      Err(Err::Failure(e)) => Err(Err::Failure(e.convert())),
+    }
+  }
+}
+
+#[cfg(test)]
+mod test {
+  use super::*;
+  use crate::bits::streaming::take;
+  use crate::error::Error;
+  use crate::sequence::tuple;
+
+  #[test]
+  /// Take the `bits` function and assert that remaining bytes are correctly returned, if the
+  /// previous bytes are fully consumed
+  fn test_complete_byte_consumption_bits() {
+    let input = &[0x12, 0x34, 0x56, 0x78];
+
+    // Take 3 bit slices with sizes [4, 8, 4].
+    let result: IResult<&[u8], (u8, u8, u8)> =
+      bits::<_, _, Error<(&[u8], usize)>, _, _>(tuple((take(4usize), take(8usize), take(4usize))))(
+        input,
+      );
+
+    let output = result.expect("We take 2 bytes and the input is longer than 2 bytes");
+
+    let remaining = output.0;
+    assert_eq!(remaining, [0x56, 0x78]);
+
+    let parsed = output.1;
+    assert_eq!(parsed.0, 0x01);
+    assert_eq!(parsed.1, 0x23);
+    assert_eq!(parsed.2, 0x04);
+  }
+
+  #[test]
+  /// Take the `bits` function and assert that remaining bytes are correctly returned, if the
+  /// previous bytes are NOT fully consumed. Partially consumed bytes are supposed to be dropped.
+  /// I.e. if we consume 1.5 bytes of 4 bytes, 2 bytes will be returned, bits 13-16 will be
+  /// dropped.
+  fn test_partial_byte_consumption_bits() {
+    let input = &[0x12, 0x34, 0x56, 0x78];
+
+    // Take bit slices with sizes [4, 8].
+    let result: IResult<&[u8], (u8, u8)> =
+      bits::<_, _, Error<(&[u8], usize)>, _, _>(tuple((take(4usize), take(8usize))))(input);
+
+    let output = result.expect("We take 1.5 bytes and the input is longer than 2 bytes");
+
+    let remaining = output.0;
+    assert_eq!(remaining, [0x56, 0x78]);
+
+    let parsed = output.1;
+    assert_eq!(parsed.0, 0x01);
+    assert_eq!(parsed.1, 0x23);
+  }
+
+  #[test]
+  #[cfg(feature = "std")]
+  /// Ensure that in Incomplete error is thrown, if too few bytes are passed for a given parser.
+  fn test_incomplete_bits() {
+    let input = &[0x12];
+
+    // Take bit slices with sizes [4, 8].
+    let result: IResult<&[u8], (u8, u8)> =
+      bits::<_, _, Error<(&[u8], usize)>, _, _>(tuple((take(4usize), take(8usize))))(input);
+
+    assert!(result.is_err());
+    let error = result.err().unwrap();
+    assert_eq!("Parsing requires 2 bytes/chars", error.to_string());
+  }
+}