Flesh out Optional members swap, reset, emplace, has_value

[folly.git] / folly / ExceptionWrapper.h

diff --git a/folly/ExceptionWrapper.h b/folly/ExceptionWrapper.h
index a1adfecdd3763110c8a9f0f0cab86bf9ee74027f..eb493fc68c10429428515a8f6459429e24d01162 100644 (file)
--- a/folly/ExceptionWrapper.h
+++ b/folly/ExceptionWrapper.h
@@ -34,7 +34,9 @@
 #include <folly/Demangle.h>
 #include <folly/ExceptionString.h>
 #include <folly/FBString.h>
+#include <folly/Portability.h>
 #include <folly/Traits.h>
+#include <folly/Utility.h>
 
 #ifdef __GNUC__
 #pragma GCC diagnostic push
@@ -42,8 +44,7 @@
 #pragma GCC diagnostic ignored "-Wpotentially-evaluated-expression"
 // GCC gets confused about lambda scopes and issues shadow-local warnings for
 // parameters in totally different functions.
-#pragma GCC diagnostic ignored "-Wshadow-local"
-#pragma GCC diagnostic ignored "-Wshadow-compatible-local"
+FOLLY_GCC_DISABLE_NEW_SHADOW_WARNINGS
 #endif
 
 #define FOLLY_EXCEPTION_WRAPPER_H_INCLUDED
@@ -196,7 +197,7 @@ class exception_wrapper final {
     exception_wrapper (*get_exception_ptr_)(exception_wrapper const*);
   };
 
-  [[noreturn]] static void onNoExceptionError();
+  [[noreturn]] static void onNoExceptionError(char const* name);
 
   template <class Ret, class... Args>
   static Ret noop_(Args...);
@@ -226,8 +227,8 @@ class exception_wrapper final {
 
     Buffer() : buff_{} {}
 
-    template <class Ex, class DEx = _t<std::decay<Ex>>>
-    Buffer(in_place_t, Ex&& ex);
+    template <class Ex, typename... As>
+    Buffer(in_place_type_t<Ex>, As&&... as_);
     template <class Ex>
     Ex& as() noexcept;
     template <class Ex>
@@ -258,8 +259,12 @@ class exception_wrapper final {
         "Surprise! std::exception and std::type_info don't have alignment "
         "greater than one. as_int_ below will not work!");
 
-    static std::uintptr_t as_int_(std::exception const& e);
-    static std::uintptr_t as_int_(AnyException e);
+    static std::uintptr_t as_int_(
+        std::exception_ptr const& ptr,
+        std::exception const& e);
+    static std::uintptr_t as_int_(
+        std::exception_ptr const& ptr,
+        AnyException e);
     bool has_exception_() const;
     std::exception const* as_exception_() const;
     std::type_info const* as_type_() const;
@@ -305,10 +310,10 @@ class exception_wrapper final {
     struct Impl final : public Base {
       Ex ex_;
       Impl() = default;
-      explicit Impl(Ex const& ex) : Base{typeid(ex)}, ex_(ex) {}
-      explicit Impl(Ex&& ex)
-          : Base{typeid(ex)},
-            ex_(std::move(ex)){}[[noreturn]] void throw_() const override;
+      template <typename... As>
+      explicit Impl(As&&... as)
+          : Base{typeid(Ex)}, ex_(std::forward<As>(as)...) {}
+      [[noreturn]] void throw_() const override;
       std::exception const* get_exception_() const noexcept override;
       exception_wrapper get_exception_ptr_() const noexcept override;
     };
@@ -331,11 +336,11 @@ class exception_wrapper final {
   };
   VTable const* vptr_{&uninit_};
 
-  template <class Ex, class DEx = _t<std::decay<Ex>>>
-  exception_wrapper(Ex&& ex, OnHeapTag);
+  template <class Ex, typename... As>
+  exception_wrapper(OnHeapTag, in_place_type_t<Ex>, As&&... as);
 
-  template <class Ex, class DEx = _t<std::decay<Ex>>>
-  exception_wrapper(Ex&& ex, InSituTag);
+  template <class Ex, typename... As>
+  exception_wrapper(InSituTag, in_place_type_t<Ex>, As&&... as);
 
   template <class T>
   struct IsRegularExceptionType
@@ -363,6 +368,9 @@ class exception_wrapper final {
   static bool with_exception_(This& this_, Fn fn_);
 
  public:
+  static exception_wrapper from_exception_ptr(
+      std::exception_ptr const& eptr) noexcept;
+
   //! Default-constructs an empty `exception_wrapper`
   //! \post `type() == none()`
   exception_wrapper() noexcept {}
@@ -430,10 +438,16 @@ class exception_wrapper final {
       FOLLY_REQUIRES(IsRegularExceptionType<Ex_>::value)>
   exception_wrapper(in_place_t, Ex&& ex);
 
+  template <
+      class Ex,
+      typename... As,
+      FOLLY_REQUIRES(IsRegularExceptionType<Ex>::value)>
+  exception_wrapper(in_place_type_t<Ex>, As&&... as);
+
   //! Swaps the value of `*this` with the value of `that`
   void swap(exception_wrapper& that) noexcept;
 
-  //! \return `true` if `*this` is not holding an exception.
+  //! \return `true` if `*this` is holding an exception.
   explicit operator bool() const noexcept;
 
   //! \return `!bool(*this)`
@@ -457,6 +471,18 @@ class exception_wrapper final {
   //! \overload
   std::exception const* get_exception() const noexcept;
 
+  //! \returns a pointer to the `Ex` held by `*this`, if it holds an object
+  //!     whose type `From` permits `std::is_convertible<From*, Ex*>`;
+  //!     otherwise, returns `nullptr`.
+  //! \note This function does not mutate the `exception_wrapper` object.
+  //! \note This function may cause an exception to be thrown and immediately
+  //!     caught internally, affecting runtime performance.
+  template <typename Ex>
+  Ex* get_exception() noexcept;
+  //! \overload
+  template <typename Ex>
+  Ex const* get_exception() const noexcept;
+
   //! \return A `std::exception_ptr` that references either the exception held
   //!     by `*this`, or a copy of same.
   //! \note This function may need to throw an exception to complete the action.
@@ -501,11 +527,6 @@ class exception_wrapper final {
   //! Throws the wrapped expression.
   [[noreturn]] void throw_exception() const;
 
-  [[noreturn]] FOLLY_DEPRECATED(
-      "use throw_exception") void throwException() const {
-    throw_exception();
-  }
-
   //! Call `fn` with the wrapped exception (if any), if `fn` can accept it.
   //! \par Example
   //! \code
@@ -587,7 +608,7 @@ constexpr exception_wrapper::VTable exception_wrapper::InPlace<Ex>::ops_;
  */
 template <class Ex, typename... As>
 exception_wrapper make_exception_wrapper(As&&... as) {
-  return exception_wrapper{Ex{std::forward<As>(as)...}};
+  return exception_wrapper{in_place_type<Ex>, std::forward<As>(as)...};
 }
 
 /**
@@ -625,7 +646,7 @@ inline exception_wrapper try_and_catch_(F&& f) {
     return exception_wrapper(std::current_exception(), ex);
   }
 }
-} // detail
+} // namespace detail
 
 //! `try_and_catch` is a simple replacement for `try {} catch(){}`` that allows
 //! you to specify which derived exceptions you would like to catch and store in
@@ -666,7 +687,7 @@ template <typename... Exceptions, typename F>
 exception_wrapper try_and_catch(F&& fn) {
   return detail::try_and_catch_<F, Exceptions...>(std::forward<F>(fn));
 }
-} // folly
+} // namespace folly
 
 #include <folly/ExceptionWrapper-inl.h>