Dictionary – Key Map

The remaining member of the Dictionary class to change to a standard class is the key hash, which was defined as a QHash.  This class is equivalent to the std::unordered_map, which also stores keys using a hash.  The member was renamed to key map and a Key Map alias was added since the the map type is rather lengthy:

using KeyMap = std::unordered_map<std::string, int>;

The add routine, was changed to use the key as a standard string.  The standard string class does not have a member function for converting the string to upper case.  For case insensitive dictionaries, the string is converted to upper case using the standard transform function:

std::transform(key.begin(), key.end(), key.begin(), toupper);

The first two arguments specify the range of the string to transform (the entire string).  The third argument specifies the destination (back into the string).  The last argument is function that takes and returns a character.  To find a key value in the map, the map find function is used, which returns an iterator.  A key not found is detected if the iterator is the end iterator of the map.  The value in the map (the index of the entry) is obtained using the iterator:

auto iterator = m_keyMap.find(key);
if (iterator == m_keyMap.end())  // key not found?
...
index = iterator->index;

Similar changes were made in the remove function for converting the key to upper case for case insensitive dictionaries.  The map erase function is used to remove a key from the map.

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