dfir_lang/graph/ops/
source_stream.rs

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1use quote::quote_spanned;
2
3use super::{
4    FloType, OperatorCategory, OperatorConstraints, OperatorWriteOutput, WriteContextArgs, RANGE_0,
5    RANGE_1,
6};
7
8/// > 0 input streams, 1 output stream
9///
10/// > Arguments: The receive end of a tokio channel
11///
12/// Given a [`Stream`](https://docs.rs/futures/latest/futures/stream/trait.Stream.html)
13/// created in Rust code, `source_stream`
14/// is passed the receive endpoint of the channel and emits each of the
15/// elements it receives downstream.
16///
17/// ```rustbook
18/// let (input_send, input_recv) = dfir_rs::util::unbounded_channel::<&str>();
19/// let mut flow = dfir_rs::dfir_syntax! {
20///     source_stream(input_recv) -> map(|x| x.to_uppercase())
21///         -> for_each(|x| println!("{}", x));
22/// };
23/// input_send.send("Hello").unwrap();
24/// input_send.send("World").unwrap();
25/// flow.run_available();
26/// ```
27pub const SOURCE_STREAM: OperatorConstraints = OperatorConstraints {
28    name: "source_stream",
29    categories: &[OperatorCategory::Source],
30    hard_range_inn: RANGE_0,
31    soft_range_inn: RANGE_0,
32    hard_range_out: RANGE_1,
33    soft_range_out: RANGE_1,
34    num_args: 1,
35    persistence_args: RANGE_0,
36    type_args: RANGE_0,
37    is_external_input: true,
38    has_singleton_output: false,
39    flo_type: Some(FloType::Source),
40    ports_inn: None,
41    ports_out: None,
42    input_delaytype_fn: |_| None,
43    write_fn: |wc @ &WriteContextArgs {
44                   root,
45                   context,
46                   op_span,
47                   ident,
48                   arguments,
49                   ..
50               },
51               _| {
52        let receiver = &arguments[0];
53        let stream_ident = wc.make_ident("stream");
54        let write_prologue = quote_spanned! {op_span=>
55            let mut #stream_ident = {
56                #[inline(always)]
57                fn check_stream<Stream: #root::futures::stream::Stream<Item = Item> + ::std::marker::Unpin, Item>(stream: Stream)
58                    -> impl #root::futures::stream::Stream<Item = Item> + ::std::marker::Unpin
59                {
60                    stream
61                }
62                check_stream(#receiver)
63            };
64        };
65        let write_iterator = quote_spanned! {op_span=>
66            let #ident = std::iter::from_fn(|| {
67                match #root::futures::stream::Stream::poll_next(::std::pin::Pin::new(&mut #stream_ident), &mut std::task::Context::from_waker(&#context.waker())) {
68                    std::task::Poll::Ready(maybe) => maybe,
69                    std::task::Poll::Pending => None,
70                }
71            });
72        };
73        Ok(OperatorWriteOutput {
74            write_prologue,
75            write_iterator,
76            ..Default::default()
77        })
78    },
79};
dfir_lang/graph/ops/source_stream.rs

dfir_lang/graph/ops/
source_stream.rs
