Merge pull request #32 from pendulum-chain/spacewalk/544-change-check…

…s-for-unknown-validators-in-stellar-relay-pallet

Add `pop` and `get_element` functions for `LimitedVarArray`

src/xdr/compound_types.rs

@@ -160,6 +160,18 @@ impl<T, const N: i32> LimitedVarArray<T, N> {
         &self.0
     }
 
+    /// Searches for an element in the array that satisfies the predicate.
+    ///
+    /// # Arguments
+    ///
+    /// * `predicate` - a closure that applies to each element of the array.
+    ///                 Returns `true` if any of them return `true`, then get_element() returns Some(element)
+    ///                 If they all return `false`, `get_element()` returns None.
+    pub fn get_element<P>(&self, mut predicate:P) -> Option<&T>
+        where P: FnMut(&T) -> bool {
+        self.0.iter().find(|elem| predicate(elem))
+    }
+
     pub fn len(&self) -> usize {
         self.0.len()
     }
@@ -175,6 +187,12 @@ impl<T, const N: i32> LimitedVarArray<T, N> {
         self.0.push(item);
         Ok(())
     }
+
+    /// Removes an element from the end of the array and returns it, or `None` if it is empty.
+    pub fn pop(&mut self) -> Option<T> {
+        self.0.pop()
+    }
+
 }
 
 impl<T: XdrCodec, const N: i32> XdrCodec for LimitedVarArray<T, N> {
@@ -295,4 +313,16 @@ mod tests {
         );
         assert_eq!(XdrArchive::<LimitedVarArray<Price, 10>>::from_xdr(encoded).unwrap(), xdr_archive)
     }
+
+    #[test]
+    fn pop_and_find_limited_array() {
+        let sample_vec = vec![0,1,2,3,4];
+        let mut sample_limited_array = LimitedVarArray::<u8,5>::new(sample_vec).expect("should return just fine");
+        let len = sample_limited_array.len();
+        let popped = sample_limited_array.pop();
+        assert_eq!(popped, Some(4));
+        assert_ne!(sample_limited_array.len(), len);
+
+        assert!(sample_limited_array.get_element(|elem| *elem == 2).is_some());
+    }
 }