issuperset

Summary:
set([1,2,3]).issuperset([1,2]) == True
>= currentlu quite hard to implement

Reviewed By: stepancheg

Differential Revision: D60527930

fbshipit-source-id: 9a22effe41ecae81838e02adb0f432691e929670

2 files changed, 53 insertions, 3 deletions

diff --git a/starlark/src/values/types/set/methods.rs b/starlark/src/values/types/set/methods.rs
index 01837b0c..ab6ade0e 100644
--- a/starlark/src/values/types/set/methods.rs
+++ b/starlark/src/values/types/set/methods.rs
@@ -301,6 +301,30 @@ pub(crate) fn set_methods(builder: &mut MethodsBuilder) {
         }
         Ok(data)
     }
+
+    /// Test whether every element other iterable is in the set.
+    /// ```
+    /// # starlark::assert::is_true(r#"
+    /// x = set([1, 2, 3])
+    /// y = [1, 3]
+    /// x.issuperset(y) == True
+    /// # "#);
+    /// ```
+    fn issuperset<'v>(
+        this: SetRef<'v>,
+        #[starlark(require=pos)] other: ValueOfUnchecked<'v, StarlarkIter<Value<'v>>>,
+        heap: &'v Heap,
+    ) -> starlark::Result<bool> {
+        let other = other.get().iterate(heap)?;
+        //TODO (romanp) skip if other is larger
+        for elem in other {
+            let hashed = elem.get_hashed()?;
+            if !this.contains_hashed(hashed) {
+                return Ok(false);
+            }
+        }
+        Ok(true)
+    }
 }
 #[cfg(test)]
 mod tests {
@@ -501,4 +525,30 @@ mod tests {
     fn test_difference_empty_rhs() {
         assert::eq("set([1, 2]).difference(set([]))", "set([2, 1])")
     }
+
+    #[test]
+    fn test_is_superset() {
+        assert::is_true("set([1, 2, 3, 4]).issuperset(set([1, 3, 2]))")
+    }
+
+    #[test]
+    fn test_is_not_superset() {
+        assert::is_false("set([1, 2]).issuperset(set([1, 3, 5]))")
+    }
+
+    #[test]
+    fn test_is_not_superset_empty_lhs() {
+        assert::is_false("set([]).issuperset(set([1]))");
+    }
+
+    #[test]
+    fn test_is_superset_empty_rhs() {
+        assert::is_true("set([1, 2]).issuperset(set([]))");
+        assert::is_true("set([]).issuperset(set([]))")
+    }
+
+    #[test]
+    fn test_is_superset_iter() {
+        assert::is_true("set([1, 2, 3]).issuperset([3, 1])")
+    }
 }
diff --git a/starlark/testcases/eval/go/set.star b/starlark/testcases/eval/go/set.star
index 28a11e4e..d1001501 100644
--- a/starlark/testcases/eval/go/set.star
+++ b/starlark/testcases/eval/go/set.star
@@ -176,9 +176,9 @@ asserts.eq(set([1,2,3,4]).difference(set([1,2,3])), set([4]))
 asserts.eq(set([1,2,3,4]) - set([1,2,3,4]), set())
 asserts.eq(set([1,2,3,4]) - set([1,2]), set([3,4]))
 
-# # issuperset: set >= set or set.issuperset(iterable)
-# asserts.true(set([1,2,3]).issuperset([1,2]))
-# asserts.true(not set([1,2,3]).issuperset(set([1,2,4])))
+# issuperset: set >= set or set.issuperset(iterable)
+asserts.true(set([1,2,3]).issuperset([1,2]))
+asserts.true(not set([1,2,3]).issuperset(set([1,2,4])))
 # asserts.true(set([1,2,3]) >= set([1,2,3]))
 # asserts.true(set([1,2,3]) >= set([1,2]))
 # asserts.true(not set([1,2,3]) >= set([1,2,4]))