Create module "adaptors/merge"

src/adaptors/merge.rs

@@ -0,0 +1,140 @@
+use std::fmt;
+use std::iter::{Peekable, FusedIterator};
+
+use crate::size_hint;
+
+pub trait MergePredicate<T> {
+    fn merge_pred(&mut self, a: &T, b: &T) -> bool;
+}
+
+#[derive(Clone, Debug)]
+pub struct MergeLte;
+
+impl<T: PartialOrd> MergePredicate<T> for MergeLte {
+    fn merge_pred(&mut self, a: &T, b: &T) -> bool {
+        a <= b
+    }
+}
+
+/// An iterator adaptor that merges the two base iterators in ascending order.
+/// If both base iterators are sorted (ascending), the result is sorted.
+///
+/// Iterator element type is `I::Item`.
+///
+/// See [`.merge()`](crate::Itertools::merge_by) for more information.
+pub type Merge<I, J> = MergeBy<I, J, MergeLte>;
+
+/// Create an iterator that merges elements in `i` and `j`.
+///
+/// [`IntoIterator`] enabled version of [`Itertools::merge`](crate::Itertools::merge).
+///
+/// ```
+/// use itertools::merge;
+///
+/// for elt in merge(&[1, 2, 3], &[2, 3, 4]) {
+///     /* loop body */
+/// }
+/// ```
+pub fn merge<I, J>(i: I, j: J) -> Merge<<I as IntoIterator>::IntoIter, <J as IntoIterator>::IntoIter>
+    where I: IntoIterator,
+          J: IntoIterator<Item = I::Item>,
+          I::Item: PartialOrd
+{
+    merge_by_new(i, j, MergeLte)
+}
+
+/// An iterator adaptor that merges the two base iterators in ascending order.
+/// If both base iterators are sorted (ascending), the result is sorted.
+///
+/// Iterator element type is `I::Item`.
+///
+/// See [`.merge_by()`](crate::Itertools::merge_by) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct MergeBy<I, J, F>
+    where I: Iterator,
+          J: Iterator<Item = I::Item>
+{
+    a: Peekable<I>,
+    b: Peekable<J>,
+    fused: Option<bool>,
+    cmp: F,
+}
+
+impl<I, J, F> fmt::Debug for MergeBy<I, J, F>
+    where I: Iterator + fmt::Debug, J: Iterator<Item = I::Item> + fmt::Debug,
+          I::Item: fmt::Debug,
+{
+    debug_fmt_fields!(MergeBy, a, b);
+}
+
+impl<T, F: FnMut(&T, &T) -> bool> MergePredicate<T> for F {
+    fn merge_pred(&mut self, a: &T, b: &T) -> bool {
+        self(a, b)
+    }
+}
+
+/// Create a `MergeBy` iterator.
+pub fn merge_by_new<I, J, F>(a: I, b: J, cmp: F) -> MergeBy<I::IntoIter, J::IntoIter, F>
+    where I: IntoIterator,
+          J: IntoIterator<Item = I::Item>,
+          F: MergePredicate<I::Item>,
+{
+    MergeBy {
+        a: a.into_iter().peekable(),
+        b: b.into_iter().peekable(),
+        fused: None,
+        cmp,
+    }
+}
+
+impl<I, J, F> Clone for MergeBy<I, J, F>
+    where I: Iterator,
+          J: Iterator<Item = I::Item>,
+          Peekable<I>: Clone,
+          Peekable<J>: Clone,
+          F: Clone
+{
+    clone_fields!(a, b, fused, cmp);
+}
+
+impl<I, J, F> Iterator for MergeBy<I, J, F>
+    where I: Iterator,
+          J: Iterator<Item = I::Item>,
+          F: MergePredicate<I::Item>
+{
+    type Item = I::Item;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let less_than = match self.fused {
+            Some(lt) => lt,
+            None => match (self.a.peek(), self.b.peek()) {
+                (Some(a), Some(b)) => self.cmp.merge_pred(a, b),
+                (Some(_), None) => {
+                    self.fused = Some(true);
+                    true
+                }
+                (None, Some(_)) => {
+                    self.fused = Some(false);
+                    false
+                }
+                (None, None) => return None,
+            }
+        };
+        if less_than {
+            self.a.next()
+        } else {
+            self.b.next()
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        // Not ExactSizeIterator because size may be larger than usize
+        size_hint::add(self.a.size_hint(), self.b.size_hint())
+    }
+}
+
+impl<I, J, F> FusedIterator for MergeBy<I, J, F>
+    where I: FusedIterator,
+          J: FusedIterator<Item = I::Item>,
+          F: MergePredicate<I::Item>
+{}

src/adaptors/mod.rs

@@ -6,16 +6,18 @@
 
 mod coalesce;
 mod map;
+mod merge;
 mod multi_product;
 pub use self::coalesce::*;
 pub use self::map::{map_into, map_ok, MapInto, MapOk};
 #[allow(deprecated)]
 pub use self::map::MapResults;
+pub use self::merge::*;
 #[cfg(feature = "use_alloc")]
 pub use self::multi_product::*;
 
 use std::fmt;
-use std::iter::{Fuse, Peekable, FromIterator, FusedIterator};
+use std::iter::{Fuse, FromIterator, FusedIterator};
 use std::marker::PhantomData;
 use crate::size_hint;
 
@@ -466,142 +468,6 @@ impl<I> ExactSizeIterator for Step<I>
     where I: ExactSizeIterator
 {}
 
-pub trait MergePredicate<T> {
-    fn merge_pred(&mut self, a: &T, b: &T) -> bool;
-}
-
-#[derive(Clone, Debug)]
-pub struct MergeLte;
-
-impl<T: PartialOrd> MergePredicate<T> for MergeLte {
-    fn merge_pred(&mut self, a: &T, b: &T) -> bool {
-        a <= b
-    }
-}
-
-/// An iterator adaptor that merges the two base iterators in ascending order.
-/// If both base iterators are sorted (ascending), the result is sorted.
-///
-/// Iterator element type is `I::Item`.
-///
-/// See [`.merge()`](crate::Itertools::merge_by) for more information.
-pub type Merge<I, J> = MergeBy<I, J, MergeLte>;
-
-/// Create an iterator that merges elements in `i` and `j`.
-///
-/// [`IntoIterator`] enabled version of [`Itertools::merge`](crate::Itertools::merge).
-///
-/// ```
-/// use itertools::merge;
-///
-/// for elt in merge(&[1, 2, 3], &[2, 3, 4]) {
-///     /* loop body */
-/// }
-/// ```
-pub fn merge<I, J>(i: I, j: J) -> Merge<<I as IntoIterator>::IntoIter, <J as IntoIterator>::IntoIter>
-    where I: IntoIterator,
-          J: IntoIterator<Item = I::Item>,
-          I::Item: PartialOrd
-{
-    merge_by_new(i, j, MergeLte)
-}
-
-/// An iterator adaptor that merges the two base iterators in ascending order.
-/// If both base iterators are sorted (ascending), the result is sorted.
-///
-/// Iterator element type is `I::Item`.
-///
-/// See [`.merge_by()`](crate::Itertools::merge_by) for more information.
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
-pub struct MergeBy<I, J, F>
-    where I: Iterator,
-          J: Iterator<Item = I::Item>
-{
-    a: Peekable<I>,
-    b: Peekable<J>,
-    fused: Option<bool>,
-    cmp: F,
-}
-
-impl<I, J, F> fmt::Debug for MergeBy<I, J, F>
-    where I: Iterator + fmt::Debug, J: Iterator<Item = I::Item> + fmt::Debug,
-          I::Item: fmt::Debug,
-{
-    debug_fmt_fields!(MergeBy, a, b);
-}
-
-impl<T, F: FnMut(&T, &T)->bool> MergePredicate<T> for F {
-    fn merge_pred(&mut self, a: &T, b: &T) -> bool {
-        self(a, b)
-    }
-}
-
-/// Create a `MergeBy` iterator.
-pub fn merge_by_new<I, J, F>(a: I, b: J, cmp: F) -> MergeBy<I::IntoIter, J::IntoIter, F>
-    where I: IntoIterator,
-          J: IntoIterator<Item = I::Item>,
-          F: MergePredicate<I::Item>,
-{
-    MergeBy {
-        a: a.into_iter().peekable(),
-        b: b.into_iter().peekable(),
-        fused: None,
-        cmp,
-    }
-}
-
-impl<I, J, F> Clone for MergeBy<I, J, F>
-    where I: Iterator,
-          J: Iterator<Item = I::Item>,
-          Peekable<I>: Clone,
-          Peekable<J>: Clone,
-          F: Clone
-{
-    clone_fields!(a, b, fused, cmp);
-}
-
-impl<I, J, F> Iterator for MergeBy<I, J, F>
-    where I: Iterator,
-          J: Iterator<Item = I::Item>,
-          F: MergePredicate<I::Item>
-{
-    type Item = I::Item;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        let less_than = match self.fused {
-            Some(lt) => lt,
-            None => match (self.a.peek(), self.b.peek()) {
-                (Some(a), Some(b)) => self.cmp.merge_pred(a, b),
-                (Some(_), None) => {
-                    self.fused = Some(true);
-                    true
-                }
-                (None, Some(_)) => {
-                    self.fused = Some(false);
-                    false
-                }
-                (None, None) => return None,
-            }
-        };
-        if less_than {
-            self.a.next()
-        } else {
-            self.b.next()
-        }
-    }
-
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        // Not ExactSizeIterator because size may be larger than usize
-        size_hint::add(self.a.size_hint(), self.b.size_hint())
-    }
-}
-
-impl<I, J, F> FusedIterator for MergeBy<I, J, F>
-    where I: FusedIterator,
-          J: FusedIterator<Item = I::Item>,
-          F: MergePredicate<I::Item>
-{}
-
 /// An iterator adaptor that borrows from a `Clone`-able iterator
 /// to only pick off elements while the predicate returns `true`.
 ///