olm/include/olm/list.hh

119 lines
3 KiB
C++

/* Copyright 2015 OpenMarket Ltd
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef OLM_LIST_HH_
#define OLM_LIST_HH_
#include <cstddef>
namespace olm {
template<typename T, std::size_t max_size>
class List {
public:
List() : _end(_data) {}
typedef T * iterator;
typedef T const * const_iterator;
T * begin() { return _data; }
T * end() { return _end; }
T const * begin() const { return _data; }
T const * end() const { return _end; }
/**
* Is the list empty?
*/
bool empty() const { return _end == _data; }
/**
* The number of items in the list.
*/
std::size_t size() const { return _end - _data; }
T & operator[](std::size_t index) { return _data[index]; }
T const & operator[](std::size_t index) const { return _data[index]; }
/**
* Erase the item from the list at the given position.
*/
void erase(T * pos) {
--_end;
while (pos != _end) {
*pos = *(pos + 1);
++pos;
}
}
/**
* Make space for an item in the list at a given position.
* If inserting the item makes the list longer than max_size then
* the end of the list is discarded.
* Returns the where the item is inserted.
*/
T * insert(T * pos) {
if (_end != _data + max_size) {
++_end;
} else if (pos == _end) {
--pos;
}
T * tmp = _end - 1;
while (tmp != pos) {
*tmp = *(tmp - 1);
--tmp;
}
return pos;
}
/**
* Make space for an item in the list at the start of the list
*/
T * insert() { return insert(begin()); }
/**
* Insert an item into the list at a given position.
* If inserting the item makes the list longer than max_size then
* the end of the list is discarded.
* Returns the where the item is inserted.
*/
T * insert(T * pos, T const & value) {
pos = insert(pos);
*pos = value;
return pos;
}
List<T, max_size> & operator=(List<T, max_size> const & other) {
if (this == &other) {
return *this;
}
T * this_pos = _data;
T * const other_pos = other._data;
while (other_pos != other._end) {
*this_pos = *other;
++this_pos;
++other_pos;
}
_end = this_pos;
return *this;
}
private:
T * _end;
T _data[max_size];
};
} // namespace olm
#endif /* OLM_LIST_HH_ */