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121 lines
3.8 KiB
C++
121 lines
3.8 KiB
C++
// SPDX-License-Identifier: BSD-2-Clause
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// author: Max Kellermann <max.kellermann@gmail.com>
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#pragma once
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#include <algorithm>
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#include <string_view>
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#include <type_traits>
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/**
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* Partition the string_view at the specified position, returning one
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* string_view until the given position and one beginning at the given
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* position.
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*/
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template<typename T>
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constexpr std::pair<std::basic_string_view<T>, std::basic_string_view<T>>
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Partition(const std::basic_string_view<T> haystack,
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const typename std::basic_string_view<T>::size_type position) noexcept
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{
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return {
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haystack.substr(0, position),
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haystack.substr(position),
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};
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}
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template<typename T>
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constexpr std::pair<std::basic_string_view<T>, std::basic_string_view<T>>
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Partition(const std::basic_string_view<T> haystack,
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const typename std::basic_string_view<T>::const_pointer position) noexcept
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{
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return Partition(haystack, position - haystack.data());
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}
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template<typename T>
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requires(!std::is_same_v<typename std::basic_string_view<T>::const_pointer,
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typename std::basic_string_view<T>::const_iterator>)
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constexpr std::pair<std::basic_string_view<T>, std::basic_string_view<T>>
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Partition(const std::basic_string_view<T> haystack,
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const typename std::basic_string_view<T>::const_iterator i) noexcept
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{
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return Partition(haystack, i - haystack.begin());
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}
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/**
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* Like Partition(), but exclude the given position from the second
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* string_view.
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*/
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template<typename T>
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constexpr std::pair<std::basic_string_view<T>, std::basic_string_view<T>>
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PartitionWithout(const std::basic_string_view<T> haystack,
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const typename std::basic_string_view<T>::size_type separator) noexcept
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{
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return {
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haystack.substr(0, separator),
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haystack.substr(separator + 1),
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};
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}
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template<typename T>
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constexpr std::pair<std::basic_string_view<T>, std::basic_string_view<T>>
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PartitionWithout(const std::basic_string_view<T> haystack,
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const typename std::basic_string_view<T>::const_pointer separator) noexcept
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{
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return PartitionWithout(haystack, separator - haystack.data());
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}
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template<typename T>
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requires(!std::is_same_v<typename std::basic_string_view<T>::const_pointer,
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typename std::basic_string_view<T>::const_iterator>)
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constexpr std::pair<std::basic_string_view<T>, std::basic_string_view<T>>
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PartitionWithout(const std::basic_string_view<T> haystack,
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const typename std::basic_string_view<T>::const_iterator separator) noexcept
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{
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return PartitionWithout(haystack, separator - haystack.begin());
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}
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/**
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* Split the string at the first occurrence of the given character.
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* If the character is not found, then the first value is the whole
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* string and the second value is nullptr.
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*/
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template<typename T>
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constexpr std::pair<std::basic_string_view<T>, std::basic_string_view<T>>
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Split(const std::basic_string_view<T> haystack, const T ch) noexcept
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{
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const auto i = haystack.find(ch);
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if (i == haystack.npos)
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return {haystack, {}};
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return PartitionWithout(haystack, i);
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}
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/**
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* Split the string at the last occurrence of the given
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* character. If the character is not found, then the first
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* value is the whole string and the second value is nullptr.
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*/
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template<typename T>
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constexpr std::pair<std::basic_string_view<T>, std::basic_string_view<T>>
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SplitLast(const std::basic_string_view<T> haystack, const T ch) noexcept
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{
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const auto i = haystack.rfind(ch);
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if (i == haystack.npos)
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return {haystack, {}};
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return PartitionWithout(haystack, i);
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}
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/**
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* Find the first character that does not match the given predicate
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* and split at this boundary.
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*/
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template<typename T, typename P>
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constexpr std::pair<std::basic_string_view<T>, std::basic_string_view<T>>
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SplitWhile(const std::basic_string_view<T> haystack, P &&predicate) noexcept
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{
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const auto i = std::find_if_not(haystack.begin(), haystack.end(),
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std::forward<P>(predicate));
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return Partition(haystack, i);
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}
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