bytesbuf 0.4.2

Types for creating and manipulating byte sequences.
Documentation 
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// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.

use std::io::IoSlice;

use bytes::Buf;

use crate::BytesView;

impl Buf for BytesView {
    #[cfg_attr(test, mutants::skip)] // Trivial forwarder.
    fn remaining(&self) -> usize {
        self.len()
    }

    #[cfg_attr(test, mutants::skip)] // Trivial forwarder.
    fn chunk(&self) -> &[u8] {
        self.first_slice()
    }

    #[cfg_attr(test, mutants::skip)] // Trivial forwarder.
    fn chunks_vectored<'a>(&'a self, dst: &mut [IoSlice<'a>]) -> usize {
        if dst.is_empty() {
            return 0;
        }

        let slice_count = self.spans_reversed.len().min(dst.len());

        for (i, span) in self.spans_reversed.iter().rev().take(slice_count).enumerate() {
            *dst.get_mut(i).expect("guarded by min()") = IoSlice::new(span);
        }

        slice_count
    }

    #[cfg_attr(test, mutants::skip)] // Trivial forwarder.
    fn advance(&mut self, cnt: usize) {
        self.advance(cnt);
    }
}

#[cfg_attr(coverage_nightly, coverage(off))]
#[cfg(test)]
mod tests {
    use new_zealand::nz;

    use super::*;
    use crate::mem::testing::FixedBlockMemory;

    #[test]
    fn buf_compat() {
        let memory = FixedBlockMemory::new(nz!(25));

        // 25 x 4
        let mut buf = memory.reserve(100);
        buf.put_byte_repeated(0x44, 100);

        let mut bytes = buf.consume_all();

        assert_eq!(Buf::remaining(&bytes), 100);

        let chunk = Buf::chunk(&bytes);
        assert_eq!(chunk.len(), 25);
        assert_eq!(chunk, &[0x44; 25]);

        Buf::advance(&mut bytes, 20);

        let chunk = Buf::chunk(&bytes);
        assert_eq!(chunk.len(), 5);
        assert_eq!(chunk, &[0x44; 5]);

        Buf::advance(&mut bytes, 5);

        let chunk = Buf::chunk(&bytes);
        assert_eq!(chunk.len(), 25);
        assert_eq!(chunk, &[0x44; 25]);

        Buf::advance(&mut bytes, 5);

        let mut io_slices = [IoSlice::new(&[]); 4];
        let n = Buf::chunks_vectored(&bytes, &mut io_slices);

        // We have already advanced past the first 30 bytes
        // but the remaining 70 should still be here for us as 20 + 25 + 25.
        assert_eq!(n, 3);

        assert_eq!(&*io_slices[0], &[0x44; 20]);
        assert_eq!(&*io_slices[1], &[0x44; 25]);
        assert_eq!(&*io_slices[2], &[0x44; 25]);
    }

    #[test]
    fn chunks_vectored_empty_dst() {
        let memory = FixedBlockMemory::new(nz!(25));
        let mut buf = memory.reserve(25);
        buf.put_byte_repeated(0x44, 25);

        let bytes = buf.consume_all();
        let n = Buf::chunks_vectored(&bytes, &mut []);
        assert_eq!(n, 0);
    }
}