The repeated sequence of allocating a CharString and CharStringByteSink,
before calling some function that writes into this, can be moved into a
single shared helper function which then is used to give all ulocimp.h
functions that write to ByteSink an overload that instead returns a
CharString, to make call sites look like perfectly normal C++ code.
Some of this code was originally written as C code and some of this code
was originally written as C++ code but made to resemble the then already
existing code that had once been C code. Changing it all to normal C++
now will make it easier and safer to work with going forward.
· Use unnamed namespace instead of static.
· Use reference instead of non-nullable pointer.
· Use bool instead of UBool.
· Use constexpr for static data.
· Use U_EXPORT instead of U_CAPI or U_CFUNC.
· Use the default calling convention instead of U_EXPORT2.
This is the normal standard way in C, C++ as well as Java and there's no
longer any reason for ICU to be different. The various internal macros
providing custom boolean constants can all be deleted and code as well
as documentation can be updated to use lowercase true/false everywhere.
This eliminates the need for scratch buffers in any code path that ends
with these functions and also eliminates the need for counting bytes,
something that ByteSink will now handle correctly when needed.
Existing calls to uloc_addLikelySubtags() and uloc_minimizeSubtags()
throughout ICU4C implementation code are also updated to instead use
either the Locale or ulocimp_* functions with the new API.
None of this should have any externally visible effect, it's all about
cleaning up implementation internals.
