A Qt based implementation of an ordered map.

An ordered map stores key-value pairs according to the insertion order of the keys. It supports a sub-set of the QMap API, as certain APIs like QMap::insertMulti() etc do not make sense for an ordered map.

OrderedMap stores keys according to their insertion order, so if you add a key that already exists, it's order is changed to being the last key in the map. Eg:

#include "orderedmap.h"
...
OrderedMap<int, int> om;
om.insert(1,1);
om.insert(2,2);
// Order of keys is [1, 2]

om.insert(1,1);
// Order of keys is [2, 1]

Here, another example that shows a map of QString > int:

OrderedMap<QString, int> map;

// put some values
map["z-key"] = 10;
map["a-key"] = 20;
map["c-key"] = 15;

// edit some values
map["a-key"] = 21;

foreach (int value, map.values()) {
    qDebug() << value;
}

// [Output will be]:
// > 10
// > 21
// > 15

foreach (QString key, map.keys()) {
    qDebug() << key << ">" << map[key];
}

// [Output will be]:
// > "z-key" > 10
// > "a-key" > 21
// > "c-key" > 15

• The key type for the OrderedMap must provide operator==() and a global hash function called qHash().

• OrderedMap currently does NOT support implicit sharing like other Qt containers. A deep-copy will be made whenever copying the container with either copy constructor or assignment operator.

OrderedMap uses a hashtable (QHash) for storing the data and a map (QLinkedList) for storing the order of the keys.