Add all_unique_with_hasher()

Author: 424ever

src/lib.rs

@@ -2333,7 +2333,32 @@ pub trait Itertools: Iterator {
         Self: Sized,
         Self::Item: Eq + Hash,
     {
-        let mut used = HashSet::new();
+        self.all_unique_with_hasher(RandomState::new())
+    }
+
+    /// Check whether all elements are unique (non equal). The specified hash builder is used for
+    /// hashing the elements. See [.all_unique](crate::Itertools::all_unique).
+    ///
+    /// ```
+    /// use std::hash::RandomState;
+    /// use itertools::Itertools;
+    ///
+    /// let data = vec![1, 2, 3, 4, 1, 5];
+    /// assert!(!data.iter().all_unique_with_hasher(RandomState::new()));
+    /// assert!(data[0..4].iter().all_unique_with_hasher(RandomState::new()));
+    /// assert!(data[1..6].iter().all_unique_with_hasher(RandomState::new()));
+    ///
+    /// let data : Option<usize> = None;
+    /// assert!(data.into_iter().all_unique_with_hasher(RandomState::new()));
+    /// ```
+    #[cfg(feature = "use_std")]
+    fn all_unique_with_hasher<S>(&mut self, hash_builder: S) -> bool
+    where
+        Self: Sized,
+        Self::Item: Eq + Hash,
+        S: BuildHasher,
+    {
+        let mut used = HashSet::with_hasher(hash_builder);
         self.all(move |elt| used.insert(elt))
     }