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//===- llvm/ADT/STLFunctionalExtras.h - Extras for <functional> -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains some extension to <functional>.
//
// No library is required when using these functions.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_STLFUNCTIONALEXTRAS_H
#define LLVM_ADT_STLFUNCTIONALEXTRAS_H
#include "llvm/ADT/STLForwardCompat.h"
#include <cstdint>
#include <type_traits>
#include <utility>
namespace llvm {
//===----------------------------------------------------------------------===//
// Extra additions to <functional>
//===----------------------------------------------------------------------===//
/// An efficient, type-erasing, non-owning reference to a callable. This is
/// intended for use as the type of a function parameter that is not used
/// after the function in question returns.
///
/// This class does not own the callable, so it is not in general safe to store
/// a function_ref.
template<typename Fn> class function_ref;
template<typename Ret, typename ...Params>
class function_ref<Ret(Params...)> {
Ret (*callback)(intptr_t callable, Params ...params) = nullptr;
intptr_t callable;
template<typename Callable>
static Ret callback_fn(intptr_t callable, Params ...params) {
return (*reinterpret_cast<Callable*>(callable))(
std::forward<Params>(params)...);
}
public:
function_ref() = default;
function_ref(std::nullptr_t) {}
template <typename Callable>
function_ref(
Callable &&callable,
// This is not the copy-constructor.
std::enable_if_t<!std::is_same<remove_cvref_t<Callable>,
function_ref>::value> * = nullptr,
// Functor must be callable and return a suitable type.
std::enable_if_t<std::is_void<Ret>::value ||
std::is_convertible<decltype(std::declval<Callable>()(
std::declval<Params>()...)),
Ret>::value> * = nullptr)
: callback(callback_fn<std::remove_reference_t<Callable>>),
callable(reinterpret_cast<intptr_t>(&callable)) {}
Ret operator()(Params ...params) const {
return callback(callable, std::forward<Params>(params)...);
}
explicit operator bool() const { return callback; }
};
} // end namespace llvm
#endif // LLVM_ADT_STLFUNCTIONALEXTRAS_H
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