39 lines
965 B
C++
39 lines
965 B
C++
// SPDX-License-Identifier: BSD-2-Clause
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// author: Max Kellermann <max.kellermann@gmail.com>
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#ifndef TRANSFORM_N_HXX
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#define TRANSFORM_N_HXX
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#include <cstddef>
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/**
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* The std::transform_n() function that is missing in the C++ standard
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* library.
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*/
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template<class InputIt, class OutputIt, class UnaryOperation>
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OutputIt
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transform_n(InputIt input, size_t n, OutputIt output,
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UnaryOperation unary_op)
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{
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while (n-- > 0)
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*output++ = unary_op(*input++);
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return output;
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}
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/**
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* Optimized overload for the above transform_n() implementation for
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* the special case that both input and output are regular pointers.
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* Turns out that most compilers generate better code this way.
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*/
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template<class InputType, class OutputType, class UnaryOperation>
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OutputType *
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transform_n(const InputType *input, size_t n, OutputType *output,
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UnaryOperation unary_op)
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{
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for (size_t i = 0; i < n; ++i)
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output[i] = unary_op(input[i]);
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return output + n;
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}
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#endif
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