Update more core operators (TimelyDataflow#555)

* Update Map

* Update Filter

* Update OkErr

* Update Input

* Update UnorderedInput

* Update ToStream

timely/src/dataflow/mod.rs

@@ -16,7 +16,7 @@
 pub use self::stream::{StreamCore, Stream};
 pub use self::scopes::{Scope, ScopeParent};
 
-pub use self::operators::input::HandleCore as InputHandleCore;
+pub use self::operators::core::input::Handle as InputHandleCore;
 pub use self::operators::input::Handle as InputHandle;
 pub use self::operators::probe::Handle as ProbeHandle;
 

timely/src/dataflow/operators/core/filter.rs

@@ -0,0 +1,41 @@
+//! Filters a stream by a predicate.
+use timely_container::{Container, PushContainer, PushInto};
+
+use crate::dataflow::channels::pact::Pipeline;
+use crate::dataflow::{Scope, StreamCore};
+use crate::dataflow::operators::generic::operator::Operator;
+
+/// Extension trait for filtering.
+pub trait Filter<C: Container> {
+    /// Returns a new instance of `self` containing only records satisfying `predicate`.
+    ///
+    /// # Examples
+    /// ```
+    /// use timely::dataflow::operators::ToStream;
+    /// use timely::dataflow::operators::core::{Filter, Inspect};
+    ///
+    /// timely::example(|scope| {
+    ///     (0..10).to_stream(scope)
+    ///            .filter(|x| *x % 2 == 0)
+    ///            .inspect(|x| println!("seen: {:?}", x));
+    /// });
+    /// ```
+    fn filter<P: FnMut(&C::Item<'_>)->bool+'static>(&self, predicate: P) -> Self;
+}
+
+impl<G: Scope, C: PushContainer> Filter<C> for StreamCore<G, C> 
+where
+    for<'a> C::Item<'a>: PushInto<C>
+{
+    fn filter<P: FnMut(&C::Item<'_>)->bool+'static>(&self, mut predicate: P) -> StreamCore<G, C> {
+        let mut container = Default::default();
+        self.unary(Pipeline, "Filter", move |_,_| move |input, output| {
+            input.for_each(|time, data| {
+                data.swap(&mut container);
+                if !container.is_empty() {
+                    output.session(&time).give_iterator(container.drain().filter(&mut predicate));
+                }
+            });
+        })
+    }
+}