1 files changed, 172 insertions, 0 deletions
diff --git a/include/boost/sqlite/detail/scalar_function.hpp b/include/boost/sqlite/detail/scalar_function.hpp
new file mode 100644
index 0000000..ee16a23
--- /dev/null
+++ b/include/boost/sqlite/detail/scalar_function.hpp
@@ -0,0 +1,172 @@
+// Copyright (c) 2023 Klemens D. Morgenstern
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef BOOST_SQLITE_DETAIL_SCALAR_FUNCTION_HPP
+#define BOOST_SQLITE_DETAIL_SCALAR_FUNCTION_HPP
+
+#include <boost/sqlite/detail/config.hpp>
+#include <boost/sqlite/cstring_ref.hpp>
+#include <boost/sqlite/memory.hpp>
+#include <boost/sqlite/result.hpp>
+#include <boost/sqlite/value.hpp>
+
+#include <boost/callable_traits/args.hpp>
+#include <boost/callable_traits/return_type.hpp>
+#include <boost/callable_traits/has_void_return.hpp>
+#include <boost/core/span.hpp>
+
+
+BOOST_SQLITE_BEGIN_NAMESPACE
+
+template<typename ... Args>
+struct context;
+
+namespace detail
+{
+
+template<typename Func, typename ... Args, std::size_t Extent>
+auto create_scalar_function_impl(sqlite3 * db,
+                                 cstring_ref name,
+                                 Func && func,
+                                 int flags,
+                                 std::tuple<context<Args...>, boost::span<value, Extent>> * ,
+                                 std::false_type /* void return */,
+                                 std::false_type /* is pointer */) -> int
+{
+  using func_type = typename std::decay<Func>::type;
+  return sqlite3_create_function_v2(
+      db, name.c_str(),
+      Extent == boost::dynamic_extent ? -1 : static_cast<int>(Extent),
+      SQLITE_UTF8 | flags,
+      new (memory_tag{}) func_type(std::forward<Func>(func)),
+      +[](sqlite3_context* ctx, int len, sqlite3_value** args)
+      {
+        auto cc = context<Args...>(ctx);
+        auto aa =  reinterpret_cast<value*>(args);
+        auto &f = *reinterpret_cast<func_type*>(sqlite3_user_data(ctx));
+        boost::span<value, Extent> vals{aa, static_cast<std::size_t>(len)};
+
+        execute_context_function(ctx, f, cc, vals);
+      }, nullptr, nullptr,
+      +[](void * ptr) noexcept {delete_(static_cast<func_type*>(ptr));}
+  );
+}
+
+template<typename Func, typename ... Args, std::size_t Extent>
+auto create_scalar_function_impl(sqlite3 * db,
+                                 cstring_ref name,
+                                 Func && func, int flags,
+                                 std::tuple<context<Args...>, boost::span<value, Extent>> * ,
+                                 std::true_type /* void return */,
+                                 std::false_type /* is pointer */) -> int
+{
+  using func_type = typename std::decay<Func>::type;
+  return sqlite3_create_function_v2(
+      db,
+      name.c_str(),
+      (Extent == boost::dynamic_extent) ? -1 : static_cast<int>(Extent),
+      SQLITE_UTF8 | flags,
+      new (memory_tag{}) func_type(std::forward<Func>(func)),
+      +[](sqlite3_context* ctx, int len, sqlite3_value** args)
+      {
+        auto cc = context<Args...>(ctx);
+        auto aa =  reinterpret_cast<value*>(args);
+        auto &f = *reinterpret_cast<func_type*>(sqlite3_user_data(ctx));
+        boost::span<value, Extent> vals{aa, static_cast<std::size_t>(len)};
+
+        execute_context_function(
+            ctx,
+            [&]()
+            {
+              f(cc, vals);
+              return result<void>();
+            });
+
+      }, nullptr, nullptr,
+      +[](void * ptr){delete_(static_cast<func_type*>(ptr));}
+  );
+}
+
+
+template<typename Func, typename ... Args, std::size_t Extent>
+auto create_scalar_function_impl(sqlite3 * db,
+                                 cstring_ref name,
+                                 Func * func, int flags,
+                                 std::tuple<context<Args...>, boost::span<value, Extent>> * ,
+                                 std::false_type /* void return */,
+                                 std::true_type /* is pointer */) -> int
+{
+  return sqlite3_create_function_v2(
+      db, name.c_str(),
+      Extent == boost::dynamic_extent ? -1 : static_cast<int>(Extent),
+      SQLITE_UTF8 | flags,
+      reinterpret_cast<void*>(func),
+      +[](sqlite3_context* ctx, int len, sqlite3_value** args)
+      {
+        auto cc = context<Args...>(ctx);
+        auto aa = reinterpret_cast<value*>(args);
+        auto  f = reinterpret_cast<Func*>(sqlite3_user_data(ctx));
+
+        boost::span<value, Extent> vals{aa, static_cast<std::size_t>(len)};
+
+        execute_context_function(
+            ctx, f, cc, vals);
+      }, nullptr, nullptr, nullptr);
+}
+
+template<typename Func, typename ... Args, std::size_t Extent>
+auto create_scalar_function_impl(sqlite3 * db,
+                                 cstring_ref name,
+                                 Func * func, int flags,
+                                 std::tuple<context<Args...>, boost::span<value, Extent>> * ,
+                                 std::true_type /* void return */,
+                                 std::true_type /* is pointer */) -> int
+{
+  return sqlite3_create_function_v2(
+      db,
+      name.c_str(),
+      (Extent == boost::dynamic_extent) ? -1 : static_cast<int>(Extent),
+      SQLITE_UTF8 | flags,
+      reinterpret_cast<void*>(func),
+      +[](sqlite3_context* ctx, int len, sqlite3_value** args)
+      {
+        auto cc = context<Args...>(ctx);
+        auto aa =  reinterpret_cast<value*>(args);
+        auto  f = *reinterpret_cast<Func*>(sqlite3_user_data(ctx));
+        boost::span<value, Extent> vals{aa, static_cast<std::size_t>(len)};
+        execute_context_function(
+            ctx,
+            [&]()
+            {
+              f(cc, vals);
+              return result<void>();
+            });
+
+      }, nullptr, nullptr, nullptr);
+}
+
+template<typename Func>
+auto create_scalar_function(sqlite3 * db,
+                     cstring_ref name,
+                     Func && func,
+                     int flags)
+                     -> decltype(create_scalar_function_impl(
+                         db, name, std::forward<Func>(func), flags,
+                         static_cast<callable_traits::args_t<Func>*>(nullptr),
+                         callable_traits::has_void_return<Func>{},
+                         std::is_pointer<typename std::decay<Func>::type>{}
+                         ))
+{
+  return create_scalar_function_impl(db, name, std::forward<Func>(func), flags,
+                                     static_cast<callable_traits::args_t<Func>*>(nullptr),
+                                     callable_traits::has_void_return<Func>{},
+                                     std::is_pointer<typename std::decay<Func>::type>{});
+}
+
+
+}
+
+BOOST_SQLITE_END_NAMESPACE
+
+#endif //BOOST_SQLITE_DETAIL_SCALAR_FUNCTION_HPP