lib: intro Collection::has_any

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>

diff --git a/lib/core/collection/abstract_collection.nit b/lib/core/collection/abstract_collection.nit
index 6b07149..ef10cfa 100644 (file)
--- a/lib/core/collection/abstract_collection.nit
+++ b/lib/core/collection/abstract_collection.nit
@@ -177,6 +177,21 @@ interface Collection[E]
                for e in self do if self.count(e) != other.count(e) then return false
                return true
        end
+
+       # Does the collection contain at least one element of `other`?
+       #
+       #     assert [1,3,4,2].has_any([1..10])    == true
+       #     assert [1,3,4,2].has_any([5..10])    == false
+       #
+       # Note that the default implementation is general and correct for any lawful Collections.
+       # It is memory-efficient but relies on `has` so may be CPU-inefficient for some kind of collections.
+       fun has_any(other: Collection[nullable Object]): Bool
+       do
+               for o in other do
+                       if has(o) then return true
+               end
+               return false
+       end
 end
 
 # Iterators generate a series of elements, one at a time.