grouping_map module behind use_alloc feature

Relax `K: Hash + Eq` bounds to soon accept `BTreeMap<K, V>`.

src/grouping_map.rs

@@ -1,11 +1,13 @@
-#![cfg(feature = "use_std")]
+#![cfg(feature = "use_alloc")]
 
 use crate::{
     adaptors::map::{MapSpecialCase, MapSpecialCaseFn},
     MinMaxResult,
 };
 use std::cmp::Ordering;
+#[cfg(feature = "use_std")]
 use std::collections::HashMap;
+#[cfg(feature = "use_std")]
 use std::hash::Hash;
 use std::iter::Iterator;
 use std::ops::{Add, Mul};
@@ -41,7 +43,6 @@ pub(crate) fn new_map_for_grouping<K, I: Iterator, F: FnMut(&I::Item) -> K>(
 pub fn new<I, K, V>(iter: I) -> GroupingMap<I>
 where
     I: Iterator<Item = (K, V)>,
-    K: Hash + Eq,
 {
     GroupingMap { iter }
 }
@@ -62,6 +63,7 @@ pub struct GroupingMap<I> {
     iter: I,
 }
 
+#[cfg(feature = "use_std")]
 impl<I, K, V> GroupingMap<I>
 where
     I: Iterator<Item = (K, V)>,

src/lib.rs

@@ -106,7 +106,7 @@ pub mod structs {
     pub use crate::groupbylazy::GroupBy;
     #[cfg(feature = "use_alloc")]
     pub use crate::groupbylazy::{Chunk, ChunkBy, Chunks, Group, Groups, IntoChunks};
-    #[cfg(feature = "use_std")]
+    #[cfg(feature = "use_alloc")]
     pub use crate::grouping_map::{GroupingMap, GroupingMapBy};
     pub use crate::intersperse::{Intersperse, IntersperseWith};
     #[cfg(feature = "use_alloc")]
@@ -191,7 +191,7 @@ mod generic_containers;
 mod group_map;
 #[cfg(feature = "use_alloc")]
 mod groupbylazy;
-#[cfg(feature = "use_std")]
+#[cfg(feature = "use_alloc")]
 mod grouping_map;
 mod intersperse;
 #[cfg(feature = "use_alloc")]
@@ -3272,11 +3272,10 @@ pub trait Itertools: Iterator {
     ///
     /// See [`GroupingMap`] for more informations
     /// on what operations are available.
-    #[cfg(feature = "use_std")]
+    #[cfg(feature = "use_alloc")]
     fn into_grouping_map<K, V>(self) -> GroupingMap<Self>
     where
         Self: Iterator<Item = (K, V)> + Sized,
-        K: Hash + Eq,
     {
         grouping_map::new(self)
     }
@@ -3289,11 +3288,10 @@ pub trait Itertools: Iterator {
     ///
     /// See [`GroupingMap`] for more informations
     /// on what operations are available.
-    #[cfg(feature = "use_std")]
+    #[cfg(feature = "use_alloc")]
     fn into_grouping_map_by<K, V, F>(self, key_mapper: F) -> GroupingMapBy<Self, F>
     where
         Self: Iterator<Item = V> + Sized,
-        K: Hash + Eq,
         F: FnMut(&V) -> K,
     {
         grouping_map::new(grouping_map::new_map_for_grouping(self, key_mapper))