Solidity iterable map

itmap.sol

library itmap {
    struct entry {
        // Equal to the index of the key of this item in keys, plus 1.
        uint keyIndex;
        uint value;
    }

    struct itmap {
        mapping(uint => entry) data;
        uint[] keys;
    }
    
    function insert(itmap storage self, uint key, uint value) internal returns (bool replaced) {
        entry storage e = self.data[key];
        e.value = value;
        if (e.keyIndex > 0) {
            return true;
        } else {
            e.keyIndex = ++self.keys.length;
            self.keys[e.keyIndex - 1] = key;
            return false;
        }
    }
    
    function remove(itmap storage self, uint key) internal returns (bool success) {
        entry storage e = self.data[key];
        if (e.keyIndex == 0)
            return false;
        
        if (e.keyIndex < self.keys.length) {
            // Move an existing element into the vacated key slot.
            self.data[self.keys[self.keys.length - 1]].keyIndex = e.keyIndex;
            self.keys[e.keyIndex - 1] = self.keys[self.keys.length - 1];
            self.keys.length -= 1;
            delete self.data[key];
            return true;
        }
    }
    
    function contains(itmap storage self, uint key) internal constant returns (bool exists) {
        return self.data[key].keyIndex > 0;
    }
    
    function size(itmap storage self) internal constant returns (uint) {
        return self.keys.length;
    }
    
    function get(itmap storage self, uint key) internal constant returns (uint) {
        return self.data[key].value;
    }
    
    function getKey(itmap storage self, uint idx) internal constant returns (uint) {
        return self.keys[idx];
    }
}

contract Test {
    // Use itmap for all functions on the struct
    using itmap for itmap.itmap;
    
    // Declare an iterable mapping
    itmap.itmap mymap;
    
    function insert(uint key, uint value) {
        mymap.insert(key, value);
    }
    
    function get(uint key) returns (uint value) {
        return mymap.get(key);
    }
}

Hi! I've tweaked this, fixed a bug (it wasn't removing the item when there was only 1 item in map) plus added a few new type mappings.
All of it in a new repo: https://github.com/szerintedmi/solidity-itMapsLib
You don't have any licence here, so I've added Apache 2.0. Please let me know if you have any issue with that license.
Suggestions about my changes are welcome too! :)