/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/pool.h is in libubuntugestures5-gles-dev 1.3.1918+16.04.20160404-0ubuntu3.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 | /*
* Copyright 2015 Canonical Ltd.
*
* This program 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; version 3.
*
* 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef UBUNTUGESTURES_POOL_H
#define UBUNTUGESTURES_POOL_H
#include <QVector>
#include "ubuntugesturesglobal.h"
/*
An object pool.
Avoids unnecessary creations/initializations and deletions/destructions of items. Useful
in a scenario where items are created and destroyed very frequently but the total number
of items at any given time remains small. They're stored in a unordered fashion.
To be used in Pool, ItemType needs to have the following methods:
- ItemType();
A constructor that takes no parameters. An object contructed with it must return false if
isValid() is called.
- bool isValid() const;
Returns wheter the object holds a valid , "filled" state or is empty.
Used by Pool to check if the slot occupied by this object is actually available.
- void reset();
Resets the object to its initial, empty, state. After calling this method, isValid() must
return false.
*/
template <class ItemType> class Pool
{
public:
Pool() : m_lastUsedIndex(-1) {
}
class Iterator {
public:
Iterator() : index(-1), item(nullptr) {}
Iterator(int index, ItemType *item)
: index(index), item(item) {}
ItemType *operator->() const { return item; }
ItemType &operator*() const { return *item; }
ItemType &value() const { return *item; }
Iterator &operator= (const Iterator& other) {
index = other.index;
item = other.item;
// by convention, always return *this
return *this;
}
operator bool() const { return item != nullptr; }
int index;
ItemType *item;
};
ItemType &getEmptySlot() {
Q_ASSERT(m_lastUsedIndex < m_slots.size());
// Look for an in-between vacancy first
for (int i = 0; i < m_lastUsedIndex; ++i) {
ItemType &item = m_slots[i];
if (!item.isValid()) {
return item;
}
}
++m_lastUsedIndex;
if (m_lastUsedIndex >= m_slots.size()) {
m_slots.resize(m_lastUsedIndex + 1);
}
return m_slots[m_lastUsedIndex];
}
void freeSlot(Iterator &iterator) {
m_slots[iterator.index].reset();
if (iterator.index == m_lastUsedIndex) {
do {
--m_lastUsedIndex;
} while (m_lastUsedIndex >= 0 && !m_slots.at(m_lastUsedIndex).isValid());
}
}
// Iterates through all valid items (i.e. the occupied slots)
// calling the given function, with the option of ending the loop early.
//
// bool Func(Iterator& item)
//
// Returning true means it wants to continue the "for" loop, false
// terminates the loop.
template<typename Func> void forEach(Func func) {
Iterator it;
for (it.index = 0; it.index <= m_lastUsedIndex; ++it.index) {
it.item = &m_slots[it.index];
if (!it.item->isValid())
continue;
if (!func(it))
break;
}
}
bool isEmpty() const { return m_lastUsedIndex == -1; }
private:
QVector<ItemType> m_slots;
int m_lastUsedIndex;
};
#endif // UBUNTUGESTURES_POOL_H
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