91 lines
2.2 KiB
C
91 lines
2.2 KiB
C
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/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include <utility>
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// The inliner doesn't take into account ARC optimizations that may occur after
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// inlining when computing the inline cost of an ObjC++ function. Here we make
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// the inlining decisions to avoid unnecessary code bloat. In effect RCTRequired
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// is a cost-free abstraction in non-DEBUG mode. In DEBUG mode we don't force
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// inlining for ease of debugging.
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#if DEBUG
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#define RCTREQUIRED_INLINE inline
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#else
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#define RCTREQUIRED_INLINE __attribute__((always_inline)) inline
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#endif
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/**
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RCTRequired<T> uses the compiler to enforce definition of a struct member
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(primitives, pointers, or objects).
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Internally, we use an implicit constructor without a default, so there has to
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be an initial value.
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Usage:
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@code
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struct S {
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RCTRequired<int> i;
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RCTRequired<NSString *> str;
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NSString *optionalStr;
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};
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S options = {
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.i = 0, // warning if omitted
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.str = @"Hello World", // warning if omitted
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};
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@endcode
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*/
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template <typename T>
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struct RCTRequired {
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/// Pass-through constructor (allows for implicit conversion) for wrapped type
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/// T
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template <typename... Args>
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RCTREQUIRED_INLINE RCTRequired(Args&&... args)
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: _t(std::forward<Args>(args)...) {
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static_assert(
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sizeof...(Args) > 0,
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"Required struct member not initialized. Expand assert trace to see where this was triggered.");
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}
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RCTREQUIRED_INLINE
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RCTRequired(const RCTRequired&) = default;
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RCTREQUIRED_INLINE
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RCTRequired(RCTRequired&&) = default;
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RCTREQUIRED_INLINE
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RCTRequired& operator=(const RCTRequired&) = default;
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RCTREQUIRED_INLINE
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RCTRequired& operator=(RCTRequired&&) = default;
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RCTREQUIRED_INLINE
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~RCTRequired() = default;
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/// Public accessor for private storage (Use when implicit conversion is
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/// impracticable)
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RCTREQUIRED_INLINE
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const T& get() const {
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return _t;
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}
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RCTREQUIRED_INLINE
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T& get() {
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return _t;
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}
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// Implicit conversion
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RCTREQUIRED_INLINE
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operator T() const {
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return _t;
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}
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RCTREQUIRED_INLINE
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operator T&() {
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return _t;
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}
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private:
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T _t;
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};
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