Converts text between Unicode (UCS-2) and the two Unicode transformation formats UTF-7 and UTF-8. There are no functions to convert directly between UTF-7 and UTF-8.

Objects of this class do not need to be created because all the member functions are static. The four functions are passed text in the second argument and output the resulting text in the first argument. Sixteen-bit descriptors are used to hold text encoded in UCS-2 (i.e. normal 16 bit Unicode), and eight-bit descriptors are used to hold text encoded in either of the transformation formats.

The conversion functions return the number of characters which were not converted because the output descriptor was not long enough to hold all of the converted text. This allows users of this class to perform partial conversions on an input descriptor, handling the case when the input descriptor is truncated mid way through a multi-byte character. The caller does not have to guess how big to make the output descriptor for a given input descriptor- they can simply do the conversion in a loop using a small output descriptor. The ability to handle truncated descriptors is particularly useful if the caller is receiving information in chunks from an external source.