Implemented 'inspect' operation

asparit/src/core/iterator.rs

@@ -8,6 +8,7 @@ use crate::{
         collect::Collect,
         copied::Copied,
         for_each::ForEach,
+        inspect::Inspect,
         map::Map,
         map_init::MapInit,
         map_with::MapWith,
@@ -435,6 +436,42 @@ pub trait ParallelIterator<'a>: Sized + Send {
         Copied::new(self)
     }
 
+    /// Applies `operation` to a reference to each item of this iterator,
+    /// producing a new iterator passing through the original items.  This is
+    /// often useful for debugging to see what's happening in iterator stages.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    ///
+    /// let a = [1, 4, 2, 3];
+    ///
+    /// // this iterator sequence is complex.
+    /// let sum = a.par_iter()
+    ///             .cloned()
+    ///             .filter(|&x| x % 2 == 0)
+    ///             .reduce(|| 0, |sum, i| sum + i);
+    ///
+    /// println!("{}", sum);
+    ///
+    /// // let's add some inspect() calls to investigate what's happening
+    /// let sum = a.par_iter()
+    ///             .cloned()
+    ///             .inspect(|x| println!("about to filter: {}", x))
+    ///             .filter(|&x| x % 2 == 0)
+    ///             .inspect(|x| println!("made it through filter: {}", x))
+    ///             .reduce(|| 0, |sum, i| sum + i);
+    ///
+    /// println!("{}", sum);
+    /// ```
+    fn inspect<O>(self, operation: O) -> Inspect<Self, O>
+    where
+        O: Fn(&Self::Item) + Clone + Send + 'a,
+    {
+        Inspect::new(self, operation)
+    }
+
     /// Reduces the items in the iterator into one item using `operation`.
     /// The argument `identity` should be a closure that can produce
     /// "identity" value which may be inserted into the sequence as

asparit/src/inner/inspect.rs

@@ -0,0 +1,342 @@
+use crate::{
+    Consumer, Executor, Folder, IndexedParallelIterator, IndexedProducer, IndexedProducerCallback,
+    ParallelIterator, Producer, ProducerCallback, Reducer,
+};
+
+/* Inspect */
+
+pub struct Inspect<X, O> {
+    base: X,
+    operation: O,
+}
+
+impl<X, O> Inspect<X, O> {
+    pub fn new(base: X, operation: O) -> Self {
+        Self { base, operation }
+    }
+}
+
+impl<'a, X, O> ParallelIterator<'a> for Inspect<X, O>
+where
+    X: ParallelIterator<'a>,
+    O: Fn(&X::Item) + Clone + Send + 'a,
+{
+    type Item = X::Item;
+
+    fn drive<E, C, D, R>(self, executor: E, consumer: C) -> E::Result
+    where
+        E: Executor<'a, D>,
+        C: Consumer<Self::Item, Result = D, Reducer = R> + 'a,
+        D: Send,
+        R: Reducer<D> + Send,
+    {
+        self.base.drive(
+            executor,
+            InspectConsumer {
+                base: consumer,
+                operation: self.operation,
+            },
+        )
+    }
+
+    fn with_producer<CB>(self, callback: CB) -> CB::Output
+    where
+        CB: ProducerCallback<'a, Self::Item>,
+    {
+        self.base.with_producer(InspectCallback {
+            base: callback,
+            operation: self.operation,
+        })
+    }
+
+    fn len_hint_opt(&self) -> Option<usize> {
+        self.base.len_hint_opt()
+    }
+}
+
+impl<'a, X, O> IndexedParallelIterator<'a> for Inspect<X, O>
+where
+    X: IndexedParallelIterator<'a>,
+    O: Fn(&X::Item) + Clone + Send + 'a,
+{
+    fn drive_indexed<E, C, D, R>(self, executor: E, consumer: C) -> E::Result
+    where
+        E: Executor<'a, D>,
+        C: Consumer<Self::Item, Result = D, Reducer = R> + 'a,
+        D: Send,
+        R: Reducer<D> + Send,
+    {
+        self.base.drive_indexed(
+            executor,
+            InspectConsumer {
+                base: consumer,
+                operation: self.operation,
+            },
+        )
+    }
+
+    fn with_producer_indexed<CB>(self, callback: CB) -> CB::Output
+    where
+        CB: IndexedProducerCallback<'a, Self::Item>,
+    {
+        self.base.with_producer_indexed(InspectCallback {
+            base: callback,
+            operation: self.operation,
+        })
+    }
+
+    fn len_hint(&self) -> usize {
+        self.base.len_hint()
+    }
+}
+
+/* InspectConsumer */
+
+struct InspectConsumer<C, O> {
+    base: C,
+    operation: O,
+}
+
+impl<'a, C, O, T> Consumer<T> for InspectConsumer<C, O>
+where
+    C: Consumer<T>,
+    O: Fn(&T) + Clone + Send,
+{
+    type Folder = InspectFolder<C::Folder, O>;
+    type Reducer = C::Reducer;
+    type Result = C::Result;
+
+    fn split(self) -> (Self, Self, Self::Reducer) {
+        let (left, right, reducer) = self.base.split();
+
+        let left = InspectConsumer {
+            base: left,
+            operation: self.operation.clone(),
+        };
+        let right = InspectConsumer {
+            base: right,
+            operation: self.operation,
+        };
+
+        (left, right, reducer)
+    }
+
+    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
+        let (left, right, reducer) = self.base.split_at(index);
+
+        let left = InspectConsumer {
+            base: left,
+            operation: self.operation.clone(),
+        };
+        let right = InspectConsumer {
+            base: right,
+            operation: self.operation,
+        };
+
+        (left, right, reducer)
+    }
+
+    fn into_folder(self) -> Self::Folder {
+        InspectFolder {
+            base: self.base.into_folder(),
+            operation: self.operation,
+        }
+    }
+
+    fn is_full(&self) -> bool {
+        self.base.is_full()
+    }
+}
+
+/* InspectFolder */
+
+struct InspectFolder<F, O> {
+    base: F,
+    operation: O,
+}
+
+impl<F, O, T> Folder<T> for InspectFolder<F, O>
+where
+    F: Folder<T>,
+    O: Fn(&T) + Clone,
+{
+    type Result = F::Result;
+
+    fn consume(mut self, item: T) -> Self {
+        (self.operation)(&item);
+
+        self.base = self.base.consume(item);
+
+        self
+    }
+
+    fn consume_iter<X>(mut self, iter: X) -> Self
+    where
+        X: IntoIterator<Item = T>,
+    {
+        self.base = self
+            .base
+            .consume_iter(iter.into_iter().inspect(self.operation.clone()));
+
+        self
+    }
+
+    fn complete(self) -> Self::Result {
+        self.base.complete()
+    }
+
+    fn is_full(&self) -> bool {
+        self.base.is_full()
+    }
+}
+
+/* InspectCallback */
+
+struct InspectCallback<CB, O> {
+    base: CB,
+    operation: O,
+}
+
+impl<'a, CB, O, T> ProducerCallback<'a, T> for InspectCallback<CB, O>
+where
+    CB: ProducerCallback<'a, T>,
+    O: Fn(&T) + Clone + Send + 'a,
+{
+    type Output = CB::Output;
+
+    fn callback<P>(self, producer: P) -> Self::Output
+    where
+        P: Producer<Item = T> + 'a,
+    {
+        self.base.callback(InspectProducer {
+            base: producer,
+            operation: self.operation,
+        })
+    }
+}
+
+impl<'a, CB, O, T> IndexedProducerCallback<'a, T> for InspectCallback<CB, O>
+where
+    CB: IndexedProducerCallback<'a, T>,
+    O: Fn(&T) + Clone + Send + 'a,
+{
+    type Output = CB::Output;
+
+    fn callback<P>(self, producer: P) -> Self::Output
+    where
+        P: IndexedProducer<Item = T> + 'a,
+    {
+        self.base.callback(InspectProducer {
+            base: producer,
+            operation: self.operation,
+        })
+    }
+}
+
+/* InspectProducer */
+
+struct InspectProducer<P, O> {
+    base: P,
+    operation: O,
+}
+
+impl<'a, P, O, T> Producer for InspectProducer<P, O>
+where
+    P: Producer<Item = T>,
+    O: Fn(&T) + Clone + Send,
+{
+    type Item = T;
+    type IntoIter = std::iter::Inspect<P::IntoIter, O>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.base.into_iter().inspect(self.operation)
+    }
+
+    fn split(self) -> (Self, Option<Self>) {
+        let operation = self.operation;
+        let (left, right) = self.base.split();
+
+        let left = InspectProducer {
+            base: left,
+            operation: operation.clone(),
+        };
+        let right = right.map(move |right| InspectProducer {
+            base: right,
+            operation,
+        });
+
+        (left, right)
+    }
+
+    fn splits(&self) -> Option<usize> {
+        self.base.splits()
+    }
+
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        self.base
+            .fold_with(InspectFolder {
+                base: folder,
+                operation: self.operation,
+            })
+            .base
+    }
+}
+
+impl<'a, P, O, T> IndexedProducer for InspectProducer<P, O>
+where
+    P: IndexedProducer<Item = T>,
+    O: Fn(&T) + Clone + Send,
+{
+    type Item = T;
+    type IntoIter = std::iter::Inspect<P::IntoIter, O>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.base.into_iter().inspect(self.operation)
+    }
+
+    fn len(&self) -> usize {
+        self.base.len()
+    }
+
+    fn split_at(self, index: usize) -> (Self, Self) {
+        let (left, right) = self.base.split_at(index);
+
+        let left = InspectProducer {
+            base: left,
+            operation: self.operation.clone(),
+        };
+        let right = InspectProducer {
+            base: right,
+            operation: self.operation,
+        };
+
+        (left, right)
+    }
+
+    fn splits(&self) -> Option<usize> {
+        self.base.splits()
+    }
+
+    fn min_len(&self) -> Option<usize> {
+        self.base.min_len()
+    }
+
+    fn max_len(&self) -> Option<usize> {
+        self.base.max_len()
+    }
+
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        self.base
+            .fold_with(InspectFolder {
+                base: folder,
+                operation: self.operation,
+            })
+            .base
+    }
+}

asparit/src/inner/mod.rs

@@ -2,6 +2,7 @@ pub mod cloned;
 pub mod collect;
 pub mod copied;
 pub mod for_each;
+pub mod inspect;
 pub mod map;
 pub mod map_init;
 pub mod map_with;
@@ -34,6 +35,7 @@ mod tests {
         let x = x
             .par_iter()
             .cloned()
+            .inspect(|x| println!("inspect: {:?}", x))
             .map_init(
                 move || i.fetch_add(1, Ordering::Relaxed),
                 |init, item| Some((*init, item)),