add embedded defer.hpp

develop/singles/headers/meta.hpp/meta_all.hpp

@@ -9,6 +9,7 @@
 #include <algorithm>
 #include <array>
 #include <atomic>
+#include <cassert>
 #include <climits>
 #include <compare>
 #include <concepts>
@@ -17,6 +18,7 @@
 #include <cstdlib>
 #include <cstring>
 #include <deque>
+#include <exception>
 #include <functional>
 #include <initializer_list>
 #include <map>
@@ -28,6 +30,8 @@
 #include <string_view>
 #include <tuple>
 #include <type_traits>
+#include <typeindex>
+#include <typeinfo>
 #include <utility>
 #include <vector>
 #include <version>
@@ -40,24 +44,19 @@
 #    define META_HPP_NO_RTTI
 #endif
 
-#if !defined(META_HPP_NO_EXCEPTIONS)
-#    include <exception>
-#endif
-
-#if !defined(META_HPP_NO_RTTI)
-#    include <typeindex>
-#    include <typeinfo>
-#endif
-
 #if !defined(META_HPP_FWD)
 #    define META_HPP_FWD(v) std::forward<decltype(v)>(v)
 #endif
 
 #if !defined(META_HPP_ASSERT)
-#    include <cassert>
 #    define META_HPP_ASSERT(...) assert(__VA_ARGS__) // NOLINT
 #endif
 
+#if !defined(META_HPP_PP_CAT)
+#    define META_HPP_PP_CAT(x, y) META_HPP_PP_CAT_I(x, y)
+#    define META_HPP_PP_CAT_I(x, y) x##y
+#endif
+
 namespace meta_hpp::detail
 {
     template < typename Enum >
@@ -303,6 +302,141 @@ namespace meta_hpp::detail
     using copy_cvref_t = typename copy_cvref<From, To>::type;
 }
 
+namespace meta_hpp::detail::impl
+{
+    template < typename F, typename... Args >
+    class defer_impl {
+    public:
+        defer_impl() = delete;
+        defer_impl(defer_impl&&) = delete;
+        defer_impl(const defer_impl&) = delete;
+        defer_impl& operator=(defer_impl&&) = delete;
+        defer_impl& operator=(const defer_impl&) = delete;
+
+        template < typename UF >
+        explicit defer_impl(UF&& f, std::tuple<Args...>&& args)
+        : f_{std::forward<UF>(f)}
+        , args_{std::move(args)} {}
+
+        void dismiss() noexcept {
+            dismissed_ = true;
+        }
+
+    protected:
+        ~defer_impl() noexcept {
+            if ( !dismissed_ ) {
+                std::apply(std::move(f_), std::move(args_));
+            }
+        }
+
+    private:
+        F f_;
+        std::tuple<Args...> args_;
+        bool dismissed_{};
+    };
+}
+
+namespace meta_hpp::detail
+{
+    template < typename F, typename... Args >
+    class defer final : public impl::defer_impl<F, Args...> {
+    public:
+        defer() = delete;
+        defer(defer&&) = delete;
+        defer(const defer&) = delete;
+        defer& operator=(defer&&) = delete;
+        defer& operator=(const defer&) = delete;
+
+        template < typename UF >
+        explicit defer(UF&& f, std::tuple<Args...>&& args)
+        : impl::defer_impl<F, Args...>{std::forward<UF>(f), std::move(args)} {}
+
+        ~defer() noexcept = default;
+    };
+
+    template < typename F, typename... Args >
+    class error_defer final : public impl::defer_impl<F, Args...> {
+    public:
+        error_defer() = delete;
+        error_defer(error_defer&&) = delete;
+        error_defer(const error_defer&) = delete;
+        error_defer& operator=(error_defer&&) = delete;
+        error_defer& operator=(const error_defer&) = delete;
+
+        template < typename UF >
+        explicit error_defer(UF&& f, std::tuple<Args...>&& args)
+        : impl::defer_impl<F, Args...>{std::forward<UF>(f), std::move(args)}
+        , exceptions_{std::uncaught_exceptions()} {}
+
+        ~error_defer() noexcept {
+            if ( exceptions_ == std::uncaught_exceptions() ) {
+                this->dismiss();
+            }
+        }
+
+    private:
+        int exceptions_{};
+    };
+
+    template < typename F, typename... Args >
+    class return_defer final : public impl::defer_impl<F, Args...> {
+    public:
+        return_defer() = delete;
+        return_defer(return_defer&&) = delete;
+        return_defer(const return_defer&) = delete;
+        return_defer& operator=(return_defer&&) = delete;
+        return_defer& operator=(const return_defer&) = delete;
+
+        template < typename UF >
+        explicit return_defer(UF&& f, std::tuple<Args...>&& args)
+        : impl::defer_impl<F, Args...>{std::forward<UF>(f), std::move(args)}
+        , exceptions_{std::uncaught_exceptions()} {}
+
+        ~return_defer() noexcept {
+            if ( exceptions_ != std::uncaught_exceptions() ) {
+                this->dismiss();
+            }
+        }
+
+    private:
+        int exceptions_{};
+    };
+
+    template < typename F, typename... Args >
+    auto make_defer(F&& f, Args&&... args) {
+        using defer_t = defer<std::decay_t<F>, std::decay_t<Args>...>;
+        return defer_t{std::forward<F>(f), std::make_tuple(std::forward<Args>(args)...)};
+    }
+
+    template < typename F, typename... Args >
+    auto make_error_defer(F&& f, Args&&... args) {
+        using defer_t = error_defer<std::decay_t<F>, std::decay_t<Args>...>;
+        return defer_t{std::forward<F>(f), std::make_tuple(std::forward<Args>(args)...)};
+    }
+
+    template < typename F, typename... Args >
+    auto make_return_defer(F&& f, Args&&... args) {
+        using defer_t = return_defer<std::decay_t<F>, std::decay_t<Args>...>;
+        return defer_t{std::forward<F>(f), std::make_tuple(std::forward<Args>(args)...)};
+    }
+}
+
+#ifdef __COUNTER__
+#    define META_HPP_DEFER(...) \
+        auto META_HPP_PP_CAT(meta_hpp_generated_defer_, __COUNTER__) { ::meta_hpp::detail::make_defer(__VA_ARGS__) }
+#    define META_HPP_ERROR_DEFER(...) \
+        auto META_HPP_PP_CAT(meta_hpp_generated_error_defer_, __COUNTER__) { ::meta_hpp::detail::make_error_defer(__VA_ARGS__) }
+#    define META_HPP_RETURN_DEFER(...) \
+        auto META_HPP_PP_CAT(meta_hpp_generated_return_defer_, __COUNTER__) { ::meta_hpp::detail::make_return_defer(__VA_ARGS__) }
+#else
+#    define META_HPP_DEFER(...) \
+        auto META_HPP_PP_CAT(meta_hpp_generated_defer_, __LINE__) { ::meta_hpp::detail::make_defer(__VA_ARGS__) }
+#    define META_HPP_ERROR_DEFER(...) \
+        auto META_HPP_PP_CAT(meta_hpp_generated_error_defer_, __LINE__) { ::meta_hpp::detail::make_error_defer(__VA_ARGS__) }
+#    define META_HPP_RETURN_DEFER(...) \
+        auto META_HPP_PP_CAT(meta_hpp_generated_return_defer_, __LINE__) { ::meta_hpp::detail::make_return_defer(__VA_ARGS__) }
+#endif
+
 #if !defined(META_HPP_NO_EXCEPTIONS)
 #    define META_HPP_TRY try
 #    define META_HPP_CATCH(...) catch ( __VA_ARGS__ )