mirror of
https://github.com/wpilibsuite/allwpilib
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59 lines
1.8 KiB
C++
59 lines
1.8 KiB
C++
// Copyright (c) FIRST and other WPILib contributors.
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// Open Source Software; you can modify and/or share it under the terms of
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// the WPILib BSD license file in the root directory of this project.
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#pragma once
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#include <cassert>
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#include <span>
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namespace wpi {
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/// Drop the first \p N elements of the array.
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template <typename T, size_t N>
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constexpr std::span<T> drop_front(std::span<T, N> in,
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typename std::span<T>::size_type n = 1) {
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assert(in.size() >= n && "Dropping more elements than exist");
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return in.subspan(n, in.size() - n);
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}
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/// Drop the last \p N elements of the array.
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template <typename T, size_t N>
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constexpr std::span<T> drop_back(std::span<T, N> in,
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typename std::span<T>::size_type n = 1) {
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assert(in.size() >= n && "Dropping more elements than exist");
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return in.subspan(0, in.size() - n);
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}
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/**
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* Returns a span equal to @p in but with only the first @p n
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* elements remaining. If @p n is greater than the length of the
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* span, the entire span is returned.
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*/
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template <typename T, size_t N>
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constexpr std::span<T> take_front(std::span<T, N> in,
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typename std::span<T>::size_type n = 1) {
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auto length = in.size();
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if (n >= length) {
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return in;
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}
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return drop_back(in, length - n);
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}
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/**
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* Returns a span equal to @p in but with only the last @p n
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* elements remaining. If @p n is greater than the length of the
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* span, the entire span is returned.
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*/
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template <typename T, size_t N>
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constexpr std::span<T> take_back(std::span<T, N> in,
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typename std::span<T>::size_type n = 1) {
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auto length = in.size();
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if (n >= length) {
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return in;
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}
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return drop_front(in, length - n);
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}
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} // namespace wpi
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