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![]() | Wide-character versions |
Support for exchange of wide-character strings is still under
consideration. The functions dealing with 8-bit character strings return
failure when operating on a wide-character atom or Prolog string object.
The functions below can extract and unify both 8-bit and wide atoms and
string objects. Wide character strings are represented as C arrays of
objects of the type pl_wchar_t
, which is guaranteed to be
the same as wchar_t
on platforms supporting this type. For
example, on MS-Windows, this represents 16-bit UCS2 characters, while
using the GNU C library (glibc) this represents 32-bit UCS4 characters.
(size_t)-1
,
it is computed from s using wcslen().PL_ATOM
, PL_STRING
,
PL_CODE_LIST
or PL_CHAR_LIST
.PL_CODE_LIST
and PL_CHAR_LIST
.
It serves two purposes. It allows for returning very long lists from
data read from a stream without the need for a resizing buffer in C.
Also, the use of difference lists is often practical for further
processing in Prolog. Examples can be found in packages/clib/readutil.c
from the source distribution.