inspircd/include/utility/iterator_range.h
2024-06-07 10:37:56 +01:00

90 lines
2.8 KiB
C++

/*
* InspIRCd -- Internet Relay Chat Daemon
*
* Copyright (C) 2020-2022 Sadie Powell <sadie@witchery.services>
*
* This file is part of InspIRCd. InspIRCd is free software: you can
* redistribute it and/or modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
namespace insp
{
template <typename Iterator>
class iterator_range;
/** Returns a range containing all elements equivalent to \p value.
* @param collection The collection to search within.
* @param value The value to search for.
*/
template <typename Collection, typename Value>
auto equal_range(const Collection& collection, const Value& value)
{
return iterator_range(collection.equal_range(value));
}
/** Returns a range representing a reverse iterator for the specified colleciton.
* @param collection The collection to create a reverse iterator for.
*/
template <typename Collection>
auto reverse_range(const Collection& collection)
{
return iterator_range(collection.rbegin(), collection.rend());
}
}
/** Represents a range of iterators. */
template <typename Iterator>
class insp::iterator_range final
{
private:
/** An iterator which points to the start of the range. */
const Iterator begini;
/* An iterator which points to one past the end of the range. */
const Iterator endi;
public:
/** Initialises a new iterator range with the specified iterators.
* @param begin An iterator which points to the start of the range.
* @param end An iterator which points to one past the end of the range.
*/
explicit iterator_range(Iterator begin, Iterator end)
: begini(begin)
, endi(end)
{
}
/** Initialises a new iterator range from a pair of iterators.
* @param range A pair of iterators in the format [first, last).
*/
explicit iterator_range(std::pair<Iterator, Iterator> range)
: begini(range.first)
, endi(range.second)
{
}
/** Determines whether the iterator range is empty. */
bool empty() const { return begini == endi; }
/** Retrieves an iterator which points to the start of the range. */
const Iterator& begin() const { return begini; }
/** Retrieves an iterator which points to one past the end of the range. */
const Iterator& end() const { return endi; }
/** Retrieves the number of hops within the iterator range. */
typename std::iterator_traits<Iterator>::difference_type count() const { return std::distance(begini, endi); }
};