Move rtc::FunctionView to the public API
Bug: webrtc:10138
Change-Id: Icc25a2a277a9608701aaddd546882366739991ca
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/127898
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27227}diff --git a/rtc_base/function_view.h b/rtc_base/function_view.h
index 91ab88e..f465cc8 100644
--- a/rtc_base/function_view.h
+++ b/rtc_base/function_view.h
@@ -11,120 +11,9 @@
#ifndef RTC_BASE_FUNCTION_VIEW_H_
#define RTC_BASE_FUNCTION_VIEW_H_
-#include <type_traits>
-#include <utility>
+// This header is deprecated and will be removed. Please use the one,
+// that is specified below instead.
-#include "rtc_base/checks.h"
-
-// Just like std::function, FunctionView will wrap any callable and hide its
-// actual type, exposing only its signature. But unlike std::function,
-// FunctionView doesn't own its callable---it just points to it. Thus, it's a
-// good choice mainly as a function argument when the callable argument will
-// not be called again once the function has returned.
-//
-// Its constructors are implicit, so that callers won't have to convert lambdas
-// and other callables to FunctionView<Blah(Blah, Blah)> explicitly. This is
-// safe because FunctionView is only a reference to the real callable.
-//
-// Example use:
-//
-// void SomeFunction(rtc::FunctionView<int(int)> index_transform);
-// ...
-// SomeFunction([](int i) { return 2 * i + 1; });
-//
-// Note: FunctionView is tiny (essentially just two pointers) and trivially
-// copyable, so it's probably cheaper to pass it by value than by const
-// reference.
-
-namespace rtc {
-
-template <typename T>
-class FunctionView; // Undefined.
-
-template <typename RetT, typename... ArgT>
-class FunctionView<RetT(ArgT...)> final {
- public:
- // Constructor for lambdas and other callables; it accepts every type of
- // argument except those noted in its enable_if call.
- template <
- typename F,
- typename std::enable_if<
- // Not for function pointers; we have another constructor for that
- // below.
- !std::is_function<typename std::remove_pointer<
- typename std::remove_reference<F>::type>::type>::value &&
-
- // Not for nullptr; we have another constructor for that below.
- !std::is_same<std::nullptr_t,
- typename std::remove_cv<F>::type>::value &&
-
- // Not for FunctionView objects; we have another constructor for that
- // (the implicitly declared copy constructor).
- !std::is_same<FunctionView,
- typename std::remove_cv<typename std::remove_reference<
- F>::type>::type>::value>::type* = nullptr>
- FunctionView(F&& f)
- : call_(CallVoidPtr<typename std::remove_reference<F>::type>) {
- f_.void_ptr = &f;
- }
-
- // Constructor that accepts function pointers. If the argument is null, the
- // result is an empty FunctionView.
- template <
- typename F,
- typename std::enable_if<std::is_function<typename std::remove_pointer<
- typename std::remove_reference<F>::type>::type>::value>::type* =
- nullptr>
- FunctionView(F&& f)
- : call_(f ? CallFunPtr<typename std::remove_pointer<F>::type> : nullptr) {
- f_.fun_ptr = reinterpret_cast<void (*)()>(f);
- }
-
- // Constructor that accepts nullptr. It creates an empty FunctionView.
- template <typename F,
- typename std::enable_if<std::is_same<
- std::nullptr_t,
- typename std::remove_cv<F>::type>::value>::type* = nullptr>
- FunctionView(F&& f) : call_(nullptr) {}
-
- // Default constructor. Creates an empty FunctionView.
- FunctionView() : call_(nullptr) {}
-
- RetT operator()(ArgT... args) const {
- RTC_DCHECK(call_);
- return call_(f_, std::forward<ArgT>(args)...);
- }
-
- // Returns true if we have a function, false if we don't (i.e., we're null).
- explicit operator bool() const { return !!call_; }
-
- private:
- union VoidUnion {
- void* void_ptr;
- void (*fun_ptr)();
- };
-
- template <typename F>
- static RetT CallVoidPtr(VoidUnion vu, ArgT... args) {
- return (*static_cast<F*>(vu.void_ptr))(std::forward<ArgT>(args)...);
- }
- template <typename F>
- static RetT CallFunPtr(VoidUnion vu, ArgT... args) {
- return (reinterpret_cast<typename std::add_pointer<F>::type>(vu.fun_ptr))(
- std::forward<ArgT>(args)...);
- }
-
- // A pointer to the callable thing, with type information erased. It's a
- // union because we have to use separate types depending on if the callable
- // thing is a function pointer or something else.
- VoidUnion f_;
-
- // Pointer to a dispatch function that knows the type of the callable thing
- // that's stored in f_, and how to call it. A FunctionView object is empty
- // (null) iff call_ is null.
- RetT (*call_)(VoidUnion, ArgT...);
-};
-
-} // namespace rtc
+#include "api/function_view.h"
#endif // RTC_BASE_FUNCTION_VIEW_H_