fbthrift 0.0.2

Facebook fork of thrift
Documentation 
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/*
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

use crate::varint;
use bufsize::SizeCounter;
use bytes::{Buf, BufMut, Bytes, BytesMut};
use std::io::Cursor;

pub trait BufExt: Buf {
    /// Reset buffer back to the beginning.
    fn reset(self) -> Self;
}

impl BufExt for Cursor<Bytes> {
    fn reset(self) -> Self {
        Cursor::new(self.into_inner())
    }
}

impl BufExt for Cursor<bytes_old::Bytes> {
    fn reset(self) -> Self {
        Cursor::new(self.into_inner())
    }
}

pub trait BufMutExt: BufMut {
    type Final: Send + 'static;

    fn put_varint_u64(&mut self, v: u64)
    where
        Self: Sized,
    {
        varint::write_u64(self, v)
    }

    fn put_varint_i64(&mut self, v: i64)
    where
        Self: Sized,
    {
        varint::write_u64(self, varint::zigzag(v))
    }

    fn finalize(self) -> Self::Final;
}

impl BufMutExt for BytesMut {
    type Final = Bytes;

    fn finalize(self) -> Self::Final {
        self.freeze()
    }
}

impl BufMutExt for SizeCounter {
    type Final = usize;

    #[inline]
    fn put_varint_u64(&mut self, v: u64) {
        self.put_uint(v, varint::u64_len(v));
    }

    #[inline]
    fn put_varint_i64(&mut self, v: i64) {
        self.put_int(v, varint::u64_len(varint::zigzag(v)));
    }

    #[inline]
    fn finalize(self) -> Self::Final {
        self.size()
    }
}

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

    #[test]
    fn test_bytes_reset() {
        let b = Bytes::from(b"hello, world".to_vec());
        let mut c = Cursor::new(b);

        assert_eq!(c.remaining(), 12);
        assert_eq!(c.get_u8(), b'h');

        c.advance(5);
        assert_eq!(c.remaining(), 6);
        assert_eq!(c.get_u8(), b' ');

        let mut c = c.reset();
        assert_eq!(c.remaining(), 12);
        assert_eq!(c.get_u8(), b'h');
    }

    #[test]
    fn test_empty_bytes_reset() {
        let b = Bytes::from(Vec::new());
        let c = Cursor::new(b);

        assert_eq!(c.remaining(), 0);

        let c = c.reset();
        assert_eq!(c.remaining(), 0);
    }
}