42 lines
1.2 KiB
Rust
42 lines
1.2 KiB
Rust
use ethers_core::types::{Log, U256};
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use futures_util::stream::{Stream, StreamExt};
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use pin_project::pin_project;
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use std::pin::Pin;
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use std::task::{Context, Poll};
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type MapEvent<'a, R, E> = Box<dyn Fn(Log) -> Result<R, E> + 'a>;
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#[pin_project]
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/// Generic wrapper around Log streams, mapping their content to a specific
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/// deserialized log struct.
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///
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/// We use this wrapper type instead of `StreamExt::map` in order to preserve
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/// information about the filter/subscription's id.
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pub struct EventStream<'a, T, R, E> {
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pub id: U256,
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#[pin]
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stream: T,
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parse: MapEvent<'a, R, E>,
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}
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impl<'a, T, R, E> EventStream<'a, T, R, E> {
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pub fn new(id: U256, stream: T, parse: MapEvent<'a, R, E>) -> Self {
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Self { id, stream, parse }
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}
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}
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impl<'a, T, R, E> Stream for EventStream<'a, T, R, E>
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where
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T: Stream<Item = Log> + Unpin,
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{
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type Item = Result<R, E>;
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fn poll_next(self: Pin<&mut Self>, ctx: &mut Context) -> Poll<Option<Self::Item>> {
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let mut this = self.project();
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match futures_util::ready!(this.stream.poll_next_unpin(ctx)) {
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Some(item) => Poll::Ready(Some((this.parse)(item))),
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None => Poll::Pending,
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}
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}
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}
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