variable_len_reader/asynchronous/
read_varint.rs

1macro_rules! read_varint_future {
2    ($primitive: ty, $future: ident) => {
3        read_varint_future!(f cfg(feature = "async_varint"), $primitive, $future, u8, ReadU8Raw);
4    };
5    (f $feature: meta, $primitive: ty, $future: ident, $internal: ty, $inner_future: ident) => {
6        #[$feature]
7        $crate::pin_project_lite::pin_project! {
8            #[cfg_attr(docsrs, doc($feature))]
9            #[derive(Debug)]
10            #[project(!Unpin)]
11            #[must_use = "futures do nothing unless you `.await` or poll them"]
12            pub struct $future<'a, R: ?Sized> {
13                value: $primitive,
14                position: usize,
15                ok: Option<bool>,
16                #[pin]
17                inner: $inner_future<'a, R>,
18            }
19        }
20        #[$feature]
21        impl<'a, R: ?Sized> ReaderFuture for $future<'a, R> {
22            fn reset(self: Pin<&mut Self>) {
23                let me = self.project();
24                *me.value = 0;
25                *me.position = 0;
26                *me.ok = None;
27                me.inner.reset();
28            }
29        }
30        #[$feature]
31        impl<'a, R: AsyncVariableReader + Unpin + ?Sized> Future for $future<'a, R> {
32            type Output = ::core::result::Result<$primitive, R::Error>;
33
34            fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
35                let mut me = self.project();
36                if let Some(ok) = me.ok.as_ref() {
37                    return Poll::Ready(if *ok { Ok(*me.value) } else { Err(R::read_varint_error(stringify!($future), *me.value as u128)) });
38                }
39                const SIZE: usize = ::core::mem::size_of::<$primitive>() << 3; // * 8
40                const NUM_BITS: $internal = <$internal>::MAX >> 1;
41                const SIGN_BIT: $internal = NUM_BITS + 1;
42                const POS_OFFSET: usize = (<$internal>::BITS - 1) as usize;
43                loop {
44                    let current = ::core::task::ready!(me.inner.as_mut().poll(cx))?;
45                    *me.value |= ((current & NUM_BITS) as $primitive) << *me.position;
46                    if current & SIGN_BIT == 0 {
47                        *me.ok = Some(true);
48                        return Poll::Ready(Ok(*me.value));
49                    }
50                    *me.position += POS_OFFSET;
51                    if *me.position >= SIZE {
52                        *me.ok = Some(false);
53                        return Poll::Ready(Err(R::read_varint_error(stringify!($future), *me.value as u128)));
54                    }
55                    me.inner.as_mut().reset();
56                }
57            }
58        }
59    };
60}
61macro_rules! read_varint_func {
62    ($func: ident, $future: ident) => {
63        read_varint_func!(f cfg(feature = "async_varint"), $func, $future, read_u8_raw);
64    };
65    (f $feature: meta, $future: ident, $func: ident, $inner_func: ident) => {
66        #[$feature]
67        #[cfg_attr(docsrs, doc($feature))]
68        #[inline]
69        fn $func(&mut self) -> $future<Self> where Self: Unpin {
70            $future { value: 0, position: 0, ok: None, inner: self.$inner_func() }
71        }
72    };
73}
74
75macro_rules! define_read_varint_future {
76    () => {
77        read_varint_future!(u16, ReadU16Varint);
78        read_varint_future!(u32, ReadU32Varint);
79        read_varint_future!(u64, ReadU64Varint);
80        read_varint_future!(u128, ReadU128Varint);
81    };
82}
83macro_rules! define_read_varint_func {
84    () => {
85        #[cfg(feature = "async_varint")]
86        #[cfg_attr(docsrs, doc(cfg(feature = "async_varint")))]
87        fn read_varint_error(future_name: &'static str, value: u128) -> Self::Error;
88
89        read_varint_func!(ReadU16Varint, read_u16_varint);
90        read_varint_func!(ReadU32Varint, read_u32_varint);
91        read_varint_func!(ReadU64Varint, read_u64_varint);
92        read_varint_func!(ReadU128Varint, read_u128_varint);
93    };
94}
95
96define_read_varint_future!();
97
98#[cfg(all(feature = "async_varint", not(feature = "async_raw")))]
99compile_error!("developer error: please check Cargo.toml");
variable_len_reader/asynchronous/read_varint.rs

variable_len_reader/asynchronous/
read_varint.rs
