mpd/src/util/StringSplit.hxx
2023-03-06 14:59:48 +01:00

94 lines
2.8 KiB
C++

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