mirror of https://github.com/JakubMelka/PDF4QT.git
131 lines
4.2 KiB
C++
131 lines
4.2 KiB
C++
// Copyright (C) 2018 Jakub Melka
|
|
//
|
|
// This file is part of PdfForQt.
|
|
//
|
|
// PdfForQt is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU Lesser General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// PdfForQt 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 Lesser General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU Lesser General Public License
|
|
// along with PDFForQt. If not, see <https://www.gnu.org/licenses/>.
|
|
|
|
|
|
#ifndef PDFFLATMAP_H
|
|
#define PDFFLATMAP_H
|
|
|
|
#include <set>
|
|
#include <array>
|
|
#include <algorithm>
|
|
|
|
namespace pdf
|
|
{
|
|
|
|
/// This class behaves like std::set, but have "flat" part, and if size of the set
|
|
/// is small (smaller than \p FlatSize), then no memory allocation is needed. This
|
|
/// container supports inserting, deleting and searching for the object presence.
|
|
template<typename Key, int FlatSize>
|
|
class PDFFlatMap
|
|
{
|
|
public:
|
|
constexpr inline PDFFlatMap();
|
|
|
|
/// Inserts a key in the container. Checks, if key is already present
|
|
/// in the container, in this case no insertion occurs.
|
|
/// \param key Key to be inserted
|
|
void insert(const Key& key);
|
|
|
|
/// Erases a key in the container, if it is in the set
|
|
/// \param key Key to be erased
|
|
void erase(const Key& key);
|
|
|
|
/// Searchs for a given key. If it is found, true is returned, false otherwise.
|
|
/// \param key Key to be searched
|
|
bool search(const Key& key) const;
|
|
|
|
/// Returns size of the container
|
|
std::size_t size() const;
|
|
|
|
/// Returns true, if container is empty
|
|
bool empty() const;
|
|
|
|
private:
|
|
/// Flat part of the set
|
|
std::array<Key, FlatSize> m_flat;
|
|
|
|
/// This iterator points to first empty position, or it is
|
|
/// the last iterator (pointing to the end of the array).
|
|
typename std::array<Key, FlatSize>::iterator m_flatEmptyPosition;
|
|
|
|
std::set<Key> m_overflowContainer;
|
|
};
|
|
|
|
template<typename Key, int FlatSize>
|
|
constexpr PDFFlatMap<Key, FlatSize>::PDFFlatMap() :
|
|
m_flat(),
|
|
m_flatEmptyPosition(m_flat.begin()),
|
|
m_overflowContainer()
|
|
{
|
|
|
|
}
|
|
|
|
template<typename Key, int FlatSize>
|
|
void PDFFlatMap<Key, FlatSize>::insert(const Key& key)
|
|
{
|
|
if (!search(key))
|
|
{
|
|
// Try to insert key in the flat part, if possible (we are not at end of the array)
|
|
if (m_flatEmptyPosition != m_flat.end())
|
|
{
|
|
*m_flatEmptyPosition++ = key;
|
|
}
|
|
else
|
|
{
|
|
m_overflowContainer.insert(key);
|
|
}
|
|
}
|
|
}
|
|
|
|
template<typename Key, int FlatSize>
|
|
void PDFFlatMap<Key, FlatSize>::erase(const Key& key)
|
|
{
|
|
// First we must check, if the key is present in the flat part. If yes, then remove key
|
|
// from the flat part and try to move one item from the overflow part to the flat part, if possible.
|
|
// Otherwise check overflow part.
|
|
m_flatEmptyPosition = std::remove_if(m_flat.begin(), m_flatEmptyPosition, [&key](const Key& otherKey) { return key == otherKey; });
|
|
m_overflowContainer.erase(key);
|
|
|
|
if (!m_overflowContainer.empty() && m_flatEmptyPosition != m_flat.end())
|
|
{
|
|
*m_flatEmptyPosition++ = *m_overflowContainer.begin();
|
|
m_overflowContainer.erase(m_overflowContainer.begin());
|
|
}
|
|
}
|
|
|
|
template<typename Key, int FlatSize>
|
|
bool PDFFlatMap<Key, FlatSize>::search(const Key& key) const
|
|
{
|
|
return std::find<typename std::array<Key, FlatSize>::const_iterator, Key>(m_flat.begin(), m_flatEmptyPosition, key) != m_flatEmptyPosition || static_cast<bool>(m_overflowContainer.count(key));
|
|
}
|
|
|
|
template<typename Key, int FlatSize>
|
|
std::size_t PDFFlatMap<Key, FlatSize>::size() const
|
|
{
|
|
return std::distance<typename std::array<Key, FlatSize>::const_iterator>(m_flat.begin(), m_flatEmptyPosition) + m_overflowContainer.size();
|
|
}
|
|
|
|
template<typename Key, int FlatSize>
|
|
bool PDFFlatMap<Key, FlatSize>::empty() const
|
|
{
|
|
return size() == 0;
|
|
}
|
|
|
|
} // namespace pdf
|
|
|
|
#endif // PDFFLATMAP_H
|