[llvm][ADT] Add wrappers to std::includes

llvm/include/llvm/ADT/STLExtras.h

@@ -1940,6 +1940,28 @@ template <typename R> bool is_sorted(R &&Range) {
   return std::is_sorted(adl_begin(Range), adl_end(Range));
 }
 
+/// Provide wrappers to std::includes which take ranges instead of having to
+/// pass begin/end explicitly.
+/// This function checks if the sorted range \p R2 is a subsequence of the
+/// sorted range \p R1. The ranges must be sorted in non-descending order.
+template <typename R1, typename R2> bool includes(R1 &&Range1, R2 &&Range2) {
+  assert(is_sorted(Range1) && "Range1 must be sorted in non-descending order");
+  assert(is_sorted(Range2) && "Range2 must be sorted in non-descending order");
+  return std::includes(adl_begin(Range1), adl_end(Range1), adl_begin(Range2),
+                       adl_end(Range2));
+}
+
+/// This function checks if the sorted range \p R2 is a subsequence of the
+/// sorted range \p R1. The ranges must be sorted with respect to a comparator
+/// \p C.
+template <typename R1, typename R2, typename Compare>
+bool includes(R1 &&Range1, R2 &&Range2, Compare &&C) {
+  assert(is_sorted(Range1, C) && "Range1 must be sorted with respect to C");
+  assert(is_sorted(Range2, C) && "Range2 must be sorted with respect to C");
+  return std::includes(adl_begin(Range1), adl_end(Range1), adl_begin(Range2),
+                       adl_end(Range2), std::forward<Compare>(C));
+}
+
 /// Wrapper function around std::count to count the number of times an element
 /// \p Element occurs in the given range \p Range.
 template <typename R, typename E> auto count(R &&Range, const E &Element) {

llvm/unittests/ADT/STLExtrasTest.cpp

@@ -1567,6 +1567,30 @@ TEST(STLExtrasTest, Mismatch) {
   }
 }
 
+TEST(STLExtrasTest, Includes) {
+  {
+    std::vector<int> V1 = {1, 2};
+    std::vector<int> V2;
+    EXPECT_TRUE(includes(V1, V2));
+    EXPECT_FALSE(includes(V2, V1));
+    V2.push_back(1);
+    EXPECT_TRUE(includes(V1, V2));
+    V2.push_back(3);
+    EXPECT_FALSE(includes(V1, V2));
+  }
+
+  {
+    std::vector<int> V1 = {3, 2, 1};
+    std::vector<int> V2;
+    EXPECT_TRUE(includes(V1, V2, std::greater<>()));
+    EXPECT_FALSE(includes(V2, V1, std::greater<>()));
+    V2.push_back(3);
+    EXPECT_TRUE(includes(V1, V2, std::greater<>()));
+    V2.push_back(0);
+    EXPECT_FALSE(includes(V1, V2, std::greater<>()));
+  }
+}
+
 struct Foo;
 struct Bar {};