# iter.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/httparse-1.3.6/src/iter.rs`.
Keywords: rust, rustlang, rust-lang

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    use core::slice;

    pub struct Bytes<'a> {
        slice: &'a [u8],
        pos: usize
    }

    impl<'a> Bytes<'a> {
        #[inline]
        pub fn new(slice: &'a [u8]) -> Bytes<'a> {
            Bytes {
                slice: slice,
                pos: 0
            }
        }

        #[inline]
        pub fn pos(&self) -> usize {
            self.pos
        }

        #[inline]
        pub fn peek(&self) -> Option<u8> {
            self.slice.get(self.pos).cloned()
        }

        #[inline]
        pub unsafe fn bump(&mut self) {
            debug_assert!(self.pos + 1 <= self.slice.len(), "overflow");
            self.pos += 1;
        }

        #[allow(unused)]
        #[inline]
        pub unsafe fn advance(&mut self, n: usize) {
            debug_assert!(self.pos + n <= self.slice.len(), "overflow");
            self.pos += n;
        }

        #[inline]
        pub fn len(&self) -> usize {
            self.slice.len()
        }

        #[inline]
        pub fn slice(&mut self) -> &'a [u8] {
            // not moving position at all, so it's safe
            unsafe {
                self.slice_skip(0)
            }
        }

        #[inline]
        pub unsafe fn slice_skip(&mut self, skip: usize) -> &'a [u8] {
            debug_assert!(self.pos >= skip);
            let head_pos = self.pos - skip;
            let ptr = self.slice.as_ptr();
            let head = slice::from_raw_parts(ptr, head_pos);
            let tail = slice::from_raw_parts(ptr.offset(self.pos as isize), self.slice.len() - self.pos);
            self.pos = 0;
            self.slice = tail;
            head
        }

        #[inline]
        pub fn next_8<'b>(&'b mut self) -> Option<Bytes8<'b, 'a>> {
            if self.slice.len() >= self.pos + 8 {
                Some(Bytes8::new(self))
            } else {
                None
            }
        }
    }

    impl<'a> AsRef<[u8]> for Bytes<'a> {
        #[inline]
        fn as_ref(&self) -> &[u8] {
            &self.slice[self.pos..]
        }
    }

    impl<'a> Iterator for Bytes<'a> {
        type Item = u8;

        #[inline]
        fn next(&mut self) -> Option<u8> {
            if self.slice.len() > self.pos {
                let b = unsafe { *self.slice.get_unchecked(self.pos) };
                self.pos += 1;
                Some(b)
            } else {
                None
            }
        }
    }

    pub struct Bytes8<'a, 'b: 'a> {
        bytes: &'a mut Bytes<'b>,
        #[cfg(debug_assertions)]
        pos: usize
    }

    macro_rules! bytes8_methods {
        ($f:ident, $pos:expr) => {
            #[inline]
            pub fn $f(&mut self) -> u8 {
                self.assert_pos($pos);
                let b = unsafe { *self.bytes.slice.get_unchecked(self.bytes.pos) };
                self.bytes.pos += 1;
                b
            }
        };
        () => {
            bytes8_methods!(_0, 0);
            bytes8_methods!(_1, 1);
            bytes8_methods!(_2, 2);
            bytes8_methods!(_3, 3);
            bytes8_methods!(_4, 4);
            bytes8_methods!(_5, 5);
            bytes8_methods!(_6, 6);
            bytes8_methods!(_7, 7);
        }
    }

    impl<'a, 'b: 'a> Bytes8<'a, 'b> {
        bytes8_methods! {}

        #[cfg(not(debug_assertions))]
        #[inline]
        fn new(bytes: &'a mut Bytes<'b>) -> Bytes8<'a, 'b> {
            Bytes8 {
                bytes: bytes,
            }
        }

        #[cfg(debug_assertions)]
        #[inline]
        fn new(bytes: &'a mut Bytes<'b>) -> Bytes8<'a, 'b> {
            Bytes8 {
                bytes: bytes,
                pos: 0,
            }
        }

        #[cfg(not(debug_assertions))]
        #[inline]
        fn assert_pos(&mut self, _pos: usize) {
        }

        #[cfg(debug_assertions)]
        #[inline]
        fn assert_pos(&mut self, pos: usize) {
            assert!(self.pos == pos);
            self.pos += 1;
        }
    }

    #[cfg(test)]
    mod tests {
        use super::Bytes;

        #[test]
        fn test_next_8_too_short() {
            // Start with 10 bytes.
            let slice = [0u8, 1u8, 2u8, 3u8, 4u8, 5u8, 6u8, 7u8, 8u8, 9u8];
            let mut bytes = Bytes::new(&slice);
            // Skip 3 of them.
            unsafe { bytes.advance(3); }
            // There should be 7 left, not enough to call next_8.
            assert!(bytes.next_8().is_none());
        }

        #[test]
        fn test_next_8_just_right() {
            // Start with 10 bytes.
            let slice = [0u8, 1u8, 2u8, 3u8, 4u8, 5u8, 6u8, 7u8, 8u8, 9u8];
            let mut bytes = Bytes::new(&slice);
            // Skip 2 of them.
            unsafe { bytes.advance(2); }
            // There should be 8 left, just enough to call next_8.
            let ret = bytes.next_8();
            assert!(ret.is_some());
            let mut ret = ret.unwrap();
            // They should be the bytes starting with 2.
            assert_eq!(ret._0(), 2u8);
            assert_eq!(ret._1(), 3u8);
            assert_eq!(ret._2(), 4u8);
            assert_eq!(ret._3(), 5u8);
            assert_eq!(ret._4(), 6u8);
            assert_eq!(ret._5(), 7u8);
            assert_eq!(ret._6(), 8u8);
            assert_eq!(ret._7(), 9u8);
        }

        #[test]
        fn test_next_8_extra() {
            // Start with 10 bytes.
            let slice = [0u8, 1u8, 2u8, 3u8, 4u8, 5u8, 6u8, 7u8, 8u8, 9u8];
            let mut bytes = Bytes::new(&slice);
            // Skip 1 of them.
            unsafe { bytes.advance(1); }
            // There should be 9 left, more than enough to call next_8.
            let ret = bytes.next_8();
            assert!(ret.is_some());
            let mut ret = ret.unwrap();
            // They should be the bytes starting with 1.
            assert_eq!(ret._0(), 1u8);
            assert_eq!(ret._1(), 2u8);
            assert_eq!(ret._2(), 3u8);
            assert_eq!(ret._3(), 4u8);
            assert_eq!(ret._4(), 5u8);
            assert_eq!(ret._5(), 6u8);
            assert_eq!(ret._6(), 7u8);
            assert_eq!(ret._7(), 8u8);
        }
    }