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//! Extension methods for `StreamVec` containing `Result`s.
use crate::dataflow::operators::vec::Map;
use crate::progress::Timestamp;
use crate::dataflow::StreamVec;
/// Extension trait for `StreamVec`.
pub trait ResultStream<'scope, T: Timestamp, D: 'static, E: 'static> {
/// Returns a new instance of `self` containing only `ok` records.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Inspect, vec::ResultStream};
///
/// timely::example(|scope| {
/// vec![Ok(0), Err(())].to_stream(scope)
/// .ok()
/// .inspect(|x| println!("seen: {:?}", x));
/// });
/// ```
fn ok(self) -> StreamVec<'scope, T, D>;
/// Returns a new instance of `self` containing only `err` records.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Inspect, vec::ResultStream};
///
/// timely::example(|scope| {
/// vec![Ok(0), Err(())].to_stream(scope)
/// .err()
/// .inspect(|x| println!("seen: {:?}", x));
/// });
/// ```
fn err(self) -> StreamVec<'scope, T, E>;
/// Returns a new instance of `self` applying `logic` on all `Ok` records.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Inspect, vec::ResultStream};
///
/// timely::example(|scope| {
/// vec![Ok(0), Err(())].to_stream(scope)
/// .map_ok(|x| x + 1)
/// .inspect(|x| println!("seen: {:?}", x));
/// });
/// ```
fn map_ok<D2: 'static, L: FnMut(D) -> D2 + 'static>(self, logic: L) -> StreamVec<'scope, T, Result<D2, E>>;
/// Returns a new instance of `self` applying `logic` on all `Err` records.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Inspect, vec::ResultStream};
///
/// timely::example(|scope| {
/// vec![Ok(0), Err(())].to_stream(scope)
/// .map_err(|_| 1)
/// .inspect(|x| println!("seen: {:?}", x));
/// });
/// ```
fn map_err<E2: 'static, L: FnMut(E) -> E2 + 'static>(self, logic: L) -> StreamVec<'scope, T, Result<D, E2>>;
/// Returns a new instance of `self` applying `logic` on all `Ok` records, passes through `Err`
/// records.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Inspect, vec::ResultStream};
///
/// timely::example(|scope| {
/// vec![Ok(0), Err(())].to_stream(scope)
/// .and_then(|x| Ok(1 + 1))
/// .inspect(|x| println!("seen: {:?}", x));
/// });
/// ```
fn and_then<D2: 'static, L: FnMut(D) -> Result<D2, E> + 'static>(
self,
logic: L,
) -> StreamVec<'scope, T, Result<D2, E>>;
/// Returns a new instance of `self` applying `logic` on all `Ok` records.
///
/// # Examples
/// ```
/// use timely::dataflow::operators::{ToStream, Inspect, vec::ResultStream};
///
/// timely::example(|scope| {
/// vec![Ok(1), Err(())].to_stream(scope)
/// .unwrap_or_else(|_| 0)
/// .inspect(|x| println!("seen: {:?}", x));
/// });
/// ```
fn unwrap_or_else<L: FnMut(E) -> D + 'static>(self, logic: L) -> StreamVec<'scope, T, D>;
}
impl<'scope, T: Timestamp, D: 'static, E: 'static> ResultStream<'scope, T, D, E> for StreamVec<'scope, T, Result<D, E>> {
fn ok(self) -> StreamVec<'scope, T, D> {
self.flat_map(Result::ok)
}
fn err(self) -> StreamVec<'scope, T, E> {
self.flat_map(Result::err)
}
fn map_ok<D2: 'static, L: FnMut(D) -> D2 + 'static>(self, mut logic: L) -> StreamVec<'scope, T, Result<D2, E>> {
self.map(move |r| r.map(&mut logic))
}
fn map_err<E2: 'static, L: FnMut(E) -> E2 + 'static>(self, mut logic: L) -> StreamVec<'scope, T, Result<D, E2>> {
self.map(move |r| r.map_err(&mut logic))
}
fn and_then<D2: 'static, L: FnMut(D) -> Result<D2, E> + 'static>(self, mut logic: L) -> StreamVec<'scope, T, Result<D2, E>> {
self.map(move |r| r.and_then(&mut logic))
}
fn unwrap_or_else<L: FnMut(E) -> D + 'static>(self, mut logic: L) -> StreamVec<'scope, T, D> {
self.map(move |r| r.unwrap_or_else(&mut logic))
}
}
#[cfg(test)]
mod tests {
use crate::dataflow::operators::{vec::{ToStream, ResultStream}, Capture, capture::Extract};
#[test]
fn test_ok() {
let output = crate::example(|scope| {
vec![Ok(0), Err(())].to_stream(scope)
.ok()
.capture()
});
assert_eq!(output.extract()[0].1, vec![0]);
}
#[test]
fn test_err() {
let output = crate::example(|scope| {
vec![Ok(0), Err(())].to_stream(scope)
.err()
.capture()
});
assert_eq!(output.extract()[0].1, vec![()]);
}
#[test]
fn test_map_ok() {
let output = crate::example(|scope| {
vec![Ok(0), Err(())].to_stream(scope)
.map_ok(|_| 10)
.capture()
});
assert_eq!(output.extract()[0].1, vec![Ok(10), Err(())]);
}
#[test]
fn test_map_err() {
let output = crate::example(|scope| {
vec![Ok(0), Err(())].to_stream(scope)
.map_err(|_| 10)
.capture()
});
assert_eq!(output.extract()[0].1, vec![Ok(0), Err(10)]);
}
#[test]
fn test_and_then() {
let output = crate::example(|scope| {
vec![Ok(0), Err(())].to_stream(scope)
.and_then(|_| Ok(1))
.capture()
});
assert_eq!(output.extract()[0].1, vec![Ok(1), Err(())]);
}
#[test]
fn test_unwrap_or_else() {
let output = crate::example(|scope| {
vec![Ok(0), Err(())].to_stream(scope)
.unwrap_or_else(|_| 10)
.capture()
});
assert_eq!(output.extract()[0].1, vec![0, 10]);
}
}