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23 lines
871 B
C++
23 lines
871 B
C++
#pragma once
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namespace ext
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{
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/// \brief Identity function for use with other algorithms as a pass-through.
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class identity
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{
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/** \brief Function pointer type template for converting identity to a function pointer.
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* Presumably useless, provided for completeness. */
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template <typename T> using function_ptr_t = T &&(*)(T &&);
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/** \brief Implementation of identity as a non-instance member function for taking function pointer. */
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template <typename T> static T && invoke(T && t) { return std::forward<T>(t); }
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public:
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/** \brief Returns the value passed as a sole argument using perfect forwarding. */
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template <typename T> T && operator()(T && t) const { return std::forward<T>(t); }
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/** \brief Allows conversion of identity instance to a function pointer. */
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template <typename T> operator function_ptr_t<T>() const { return &invoke; };
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};
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}
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