//===- llvm/ADT/STLExtras.h - Useful STL related functions ------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains some templates that are useful if you are working with the
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// STL at all.
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//
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// No library is required when using these functions.
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//
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//===----------------------------------------------------------------------===//
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// c10: modified from llvm::function_ref
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// c10: added more SFINAE to enable use in overloaded functions
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#pragma once
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namespace c10 {
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/// An efficient, type-erasing, non-owning reference to a callable. This is
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/// intended for use as the type of a function parameter that is not used
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/// after the function in question returns.
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///
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/// This class does not own the callable, so it is not in general safe to store
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/// a function_ref.
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template<typename Fn> class function_ref;
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template<typename Ret, typename ...Params>
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class function_ref<Ret(Params...)> {
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Ret (*callback)(intptr_t callable, Params ...params) = nullptr;
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intptr_t callable;
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template<typename Callable>
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static Ret callback_fn(intptr_t callable, Params ...params) {
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return (*reinterpret_cast<Callable*>(callable))(
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std::forward<Params>(params)...);
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}
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public:
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function_ref() = default;
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function_ref(std::nullptr_t) {}
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template <typename Callable>
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function_ref(Callable &&callable,
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typename std::enable_if<
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!std::is_same<typename std::remove_reference<Callable>::type,
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function_ref>::value>::type * = nullptr,
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typename std::enable_if<
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std::is_convertible<
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typename std::result_of<Callable&&(Params&&...)>::type,
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Ret>::value>::type * = nullptr)
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: callback(callback_fn<typename std::remove_reference<Callable>::type>),
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callable(reinterpret_cast<intptr_t>(&callable)) {}
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Ret operator()(Params ...params) const {
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return callback(callable, std::forward<Params>(params)...);
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}
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operator bool() const { return callback; }
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};
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}
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