Implemented 'count' operation

asparit/src/core/iterator.rs

@@ -9,6 +9,7 @@ use crate::{
         cloned::Cloned,
         collect::Collect,
         copied::Copied,
+        count::Count,
         filter::Filter,
         filter_map::FilterMap,
         flatten::{FlatMapIter, FlattenIter},
@@ -290,6 +291,21 @@ pub trait ParallelIterator<'a>: Sized + Send {
         TryForEachInit::new(self, init, operation)
     }
 
+    /// Counts the number of items in this parallel iterator.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    ///
+    /// let count = (0..100).into_par_iter().count();
+    ///
+    /// assert_eq!(count, 100);
+    /// ```
+    fn count(self) -> Count<Self> {
+        Count::new(self)
+    }
+
     /// Applies `operation` to each item of this iterator, producing a new
     /// iterator with the results.
     ///

asparit/src/inner/count.rs

@@ -0,0 +1,23 @@
+use crate::{Driver, Executor, ParallelIterator};
+
+pub struct Count<X> {
+    iterator: X,
+}
+
+impl<X> Count<X> {
+    pub fn new(iterator: X) -> Self {
+        Self { iterator }
+    }
+}
+
+impl<'a, X> Driver<'a, usize> for Count<X>
+where
+    X: ParallelIterator<'a>,
+{
+    fn exec_with<E>(self, executor: E) -> E::Result
+    where
+        E: Executor<'a, usize>,
+    {
+        self.iterator.map(|_| 1).sum().exec_with(executor)
+    }
+}

asparit/src/inner/mod.rs

@@ -1,6 +1,7 @@
 pub mod cloned;
 pub mod collect;
 pub mod copied;
+pub mod count;
 pub mod filter;
 pub mod filter_map;
 pub mod flatten;