[ADT] Add an llvm::erase_if utility to make the standard erase+remove_if

pattern easier to write.

Differential Revision: https://reviews.llvm.org/D28120

llvm-svn: 290555

llvm/include/llvm/ADT/STLExtras.h

@@ -815,6 +815,18 @@ auto partition(R &&Range, UnaryPredicate P) -> decltype(std::begin(Range)) {
   return std::partition(std::begin(Range), std::end(Range), P);
 }
 
+/// Provide a container algorithm similar to C++ Library Fundamentals v2's
+/// `erase_if` which is equivalent to:
+///
+///   C.erase(remove_if(C, pred), C.end());
+///
+/// This version works for any container with an erase method call accepting
+/// two iterators.
+template <typename Container, typename UnaryPredicate>
+void erase_if(Container &C, UnaryPredicate P) {
+  C.erase(remove_if(C, P), C.end());
+}
+
 //===----------------------------------------------------------------------===//
 //     Extra additions to <memory>
 //===----------------------------------------------------------------------===//

llvm/unittests/ADT/STLExtrasTest.cpp

@@ -297,4 +297,15 @@ TEST(STLExtrasTest, PartitionAdaptor) {
   EXPECT_EQ(7, V[7]);
 }
 
+TEST(STLExtrasTest, EraseIf) {
+  std::vector<int> V = {1, 2, 3, 4, 5, 6, 7, 8};
+
+  erase_if(V, [](int i) { return i % 2 == 0; });
+  EXPECT_EQ(4u, V.size());
+  EXPECT_EQ(1, V[0]);
+  EXPECT_EQ(3, V[1]);
+  EXPECT_EQ(5, V[2]);
+  EXPECT_EQ(7, V[3]);
+}
+
 }