# read_int.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/io/util/read_int.rs`.
Keywords: rust, rustlang, rust-lang

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    use crate::io::{AsyncRead, ReadBuf};

    use bytes::Buf;
    use pin_project_lite::pin_project;
    use std::future::Future;
    use std::io;
    use std::io::ErrorKind::UnexpectedEof;
    use std::marker::PhantomPinned;
    use std::mem::size_of;
    use std::pin::Pin;
    use std::task::{Context, Poll};

    macro_rules! reader {
        ($name:ident, $ty:ty, $reader:ident) => {
            reader!($name, $ty, $reader, size_of::<$ty>());
        };
        ($name:ident, $ty:ty, $reader:ident, $bytes:expr) => {
            pin_project! {
                #[doc(hidden)]
                #[must_use = "futures do nothing unless you `.await` or poll them"]
                pub struct $name<R> {
                    #[pin]
                    src: R,
                    buf: [u8; $bytes],
                    read: u8,
                    // Make this future `!Unpin` for compatibility with async trait methods.
                    #[pin]
                    _pin: PhantomPinned,
                }
            }

            impl<R> $name<R> {
                pub(crate) fn new(src: R) -> Self {
                    $name {
                        src,
                        buf: [0; $bytes],
                        read: 0,
                        _pin: PhantomPinned,
                    }
                }
            }

            impl<R> Future for $name<R>
            where
                R: AsyncRead,
            {
                type Output = io::Result<$ty>;

                fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
                    let mut me = self.project();

                    if *me.read == $bytes as u8 {
                        return Poll::Ready(Ok(Buf::$reader(&mut &me.buf[..])));
                    }

                    while *me.read < $bytes as u8 {
                        let mut buf = ReadBuf::new(&mut me.buf[*me.read as usize..]);

                        *me.read += match me.src.as_mut().poll_read(cx, &mut buf) {
                            Poll::Pending => return Poll::Pending,
                            Poll::Ready(Err(e)) => return Poll::Ready(Err(e.into())),
                            Poll::Ready(Ok(())) => {
                                let n = buf.filled().len();
                                if n == 0 {
                                    return Poll::Ready(Err(UnexpectedEof.into()));
                                }

                                n as u8
                            }
                        };
                    }

                    let num = Buf::$reader(&mut &me.buf[..]);

                    Poll::Ready(Ok(num))
                }
            }
        };
    }

    macro_rules! reader8 {
        ($name:ident, $ty:ty) => {
            pin_project! {
                /// Future returned from `read_u8`
                #[doc(hidden)]
                #[must_use = "futures do nothing unless you `.await` or poll them"]
                pub struct $name<R> {
                    #[pin]
                    reader: R,
                    // Make this future `!Unpin` for compatibility with async trait methods.
                    #[pin]
                    _pin: PhantomPinned,
                }
            }

            impl<R> $name<R> {
                pub(crate) fn new(reader: R) -> $name<R> {
                    $name {
                        reader,
                        _pin: PhantomPinned,
                    }
                }
            }

            impl<R> Future for $name<R>
            where
                R: AsyncRead,
            {
                type Output = io::Result<$ty>;

                fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
                    let me = self.project();

                    let mut buf = [0; 1];
                    let mut buf = ReadBuf::new(&mut buf);
                    match me.reader.poll_read(cx, &mut buf) {
                        Poll::Pending => Poll::Pending,
                        Poll::Ready(Err(e)) => Poll::Ready(Err(e.into())),
                        Poll::Ready(Ok(())) => {
                            if buf.filled().len() == 0 {
                                return Poll::Ready(Err(UnexpectedEof.into()));
                            }

                            Poll::Ready(Ok(buf.filled()[0] as $ty))
                        }
                    }
                }
            }
        };
    }

    reader8!(ReadU8, u8);
    reader8!(ReadI8, i8);

    reader!(ReadU16, u16, get_u16);
    reader!(ReadU32, u32, get_u32);
    reader!(ReadU64, u64, get_u64);
    reader!(ReadU128, u128, get_u128);

    reader!(ReadI16, i16, get_i16);
    reader!(ReadI32, i32, get_i32);
    reader!(ReadI64, i64, get_i64);
    reader!(ReadI128, i128, get_i128);

    reader!(ReadU16Le, u16, get_u16_le);
    reader!(ReadU32Le, u32, get_u32_le);
    reader!(ReadU64Le, u64, get_u64_le);
    reader!(ReadU128Le, u128, get_u128_le);

    reader!(ReadI16Le, i16, get_i16_le);
    reader!(ReadI32Le, i32, get_i32_le);
    reader!(ReadI64Le, i64, get_i64_le);
    reader!(ReadI128Le, i128, get_i128_le);