STL support: add c++20 std::erase and std::erase_if functions

Utilities/std/cm/string

@@ -0,0 +1,42 @@
+// -*-c++-*-
+// vim: set ft=cpp:
+
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#ifndef cm_string
+#define cm_string
+
+#include <algorithm>
+#include <string> // IWYU pragma: export
+
+namespace cm {
+
+// should be updated when C++20 is finalized
+#if (__cplusplus > 201703L ||                                                 \
+     (defined(_MSVC_LANG) && _MSVC_LANG > 201703)) &&                         \
+  defined(__cpp_lib_erase_if)
+
+using std::erase;
+using std::erase_if;
+
+#else
+
+template <typename T, typename Traits, typename Allocator, typename V>
+inline void erase(std::basic_string<T, Traits, Allocator>& cont,
+                  const V& value)
+{
+  cont.erase(std::remove(cont.begin(), cont.end(), value), cont.end());
+}
+
+template <typename T, typename Traits, typename Allocator, typename Predicate>
+inline void erase_if(std::basic_string<T, Traits, Allocator>& cont,
+                     Predicate pred)
+{
+  cont.erase(std::remove_if(cont.begin(), cont.end(), pred), cont.end());
+}
+
+#endif
+
+} // namespace cm
+
+#endif