From cfddb57d3a7541083ee70b0ae9d00331b9c95671 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Sat, 9 Sep 2023 18:52:41 +0300
Subject: [PATCH] Add an overload of enum_from_string that takes a string-like
 type (such as string_view). Fixes #41.

---
 include/boost/describe/enum_from_string.hpp | 24 +++++++
 test/Jamfile                                |  2 +
 test/enum_from_string_test2.cpp             | 78 +++++++++++++++++++++
 3 files changed, 104 insertions(+)
 create mode 100644 test/enum_from_string_test2.cpp

diff --git a/include/boost/describe/enum_from_string.hpp b/include/boost/describe/enum_from_string.hpp
index 3bdc4cf..f296cf0 100644
--- a/include/boost/describe/enum_from_string.hpp
+++ b/include/boost/describe/enum_from_string.hpp
@@ -12,6 +12,7 @@
 #include <boost/describe/enumerators.hpp>
 #include <boost/mp11/algorithm.hpp>
 #include <cstring>
+#include <type_traits>
 
 #if defined(_MSC_VER) && _MSC_VER == 1900
 # pragma warning(push)
@@ -41,6 +42,29 @@ bool enum_from_string( char const* name, E& e ) noexcept
     return found;
 }
 
+template<class S, class E, class De = describe_enumerators<E>,
+    class En = std::enable_if_t<
+        std::is_same<typename S::value_type, char>::value &&
+        std::is_same<typename S::traits_type::char_type, char>::value
+    >
+>
+bool enum_from_string( S const& name, E& e ) noexcept
+{
+    bool found = false;
+
+    mp11::mp_for_each<De>([&](auto D){
+
+        if( !found && name == D.name )
+        {
+            found = true;
+            e = D.value;
+        }
+
+    });
+
+    return found;
+}
+
 } // namespace describe
 } // namespace boost
 
diff --git a/test/Jamfile b/test/Jamfile
index 86e87cf..94fc27e 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -78,6 +78,8 @@ run pedantic_bases_test.cpp
 run pedantic_members_test.cpp
   : : : <warnings>pedantic ;
 
+run enum_from_string_test2.cpp ;
+
 # examples
 
 obj describe_cxx14 : describe_cxx14.cpp ;
diff --git a/test/enum_from_string_test2.cpp b/test/enum_from_string_test2.cpp
new file mode 100644
index 0000000..cc3b3eb
--- /dev/null
+++ b/test/enum_from_string_test2.cpp
@@ -0,0 +1,78 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/describe/enum_from_string.hpp>
+#include <boost/describe/enum.hpp>
+#include <boost/core/detail/string_view.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
+
+#if !defined(BOOST_DESCRIBE_CXX14)
+
+#include <boost/config/pragma_message.hpp>
+
+BOOST_PRAGMA_MESSAGE("Skipping test because C++14 is not available")
+int main() {}
+
+#else
+
+enum E1 { v101 = 101, v102 = 102 };
+BOOST_DESCRIBE_ENUM(E1, v101, v102)
+
+enum class E2 { v201 = 201, v202 = 202 };
+BOOST_DESCRIBE_ENUM(E2, v201, v202)
+
+BOOST_DEFINE_ENUM(E3, v301, v302)
+BOOST_DEFINE_ENUM_CLASS(E4, v401, v402)
+
+template<class St> void test()
+{
+    using boost::describe::enum_from_string;
+
+    {
+        E1 w{};
+        BOOST_TEST( enum_from_string( St( "v101" ), w ) ) && BOOST_TEST_EQ( w, v101 );
+        BOOST_TEST( enum_from_string( St( "v102" ), w ) ) && BOOST_TEST_EQ( w, v102 );
+        BOOST_TEST_NOT( enum_from_string( St( "v103" ), w ) );
+    }
+
+    {
+        E2 w{};
+        BOOST_TEST( enum_from_string( St( "v201" ), w ) ) && BOOST_TEST_EQ( (int)w, (int)E2::v201 );
+        BOOST_TEST( enum_from_string( St( "v202" ), w ) ) && BOOST_TEST_EQ( (int)w, (int)E2::v202 );
+        BOOST_TEST_NOT( enum_from_string( St( "v203" ), w ) );
+    }
+
+    {
+        E3 w{};
+        BOOST_TEST( enum_from_string( St( "v301" ), w ) ) && BOOST_TEST_EQ( w, v301 );
+        BOOST_TEST( enum_from_string( St( "v302" ), w ) ) && BOOST_TEST_EQ( w, v302 );
+        BOOST_TEST_NOT( enum_from_string( St( "v303" ), w ) );
+    }
+
+    {
+        E4 w{};
+        BOOST_TEST( enum_from_string( St( "v401" ), w ) ) && BOOST_TEST_EQ( (int)w, (int)E4::v401 );
+        BOOST_TEST( enum_from_string( St( "v402" ), w ) ) && BOOST_TEST_EQ( (int)w, (int)E4::v402 );
+        BOOST_TEST_NOT( enum_from_string( St( "v403" ), w ) );
+    }
+}
+
+#if !defined(BOOST_NO_CXX17_HDR_STRING_VIEW)
+# include <string_view>
+#endif
+
+int main()
+{
+    test<std::string>();
+    test<boost::core::string_view>();
+
+#if !defined(BOOST_NO_CXX17_HDR_STRING_VIEW)
+    test<std::string_view>();
+#endif
+
+    return boost::report_errors();
+}
+
+#endif // !defined(BOOST_DESCRIBE_CXX14)