NAME¶
JudyHS - C library for creating and accessing a dynamic array, using an
array-of-bytes of a length:
Length as an
Index and a word as a
Value.
SYNOPSIS¶
PPvoid_t JudyHSIns(PPvoid_t PPJHS, void *Index, Word_t Length, PJError_t PJError);
int JudyHSDel(PPvoid_t PPJHS, void *Index, Word_t Length, PJError_t PJError);
PPvoid_t JudyHSGet(Pcvoid_t PJHS, void *Index, Word_t Length, PJError_t PJError);
Word_t JudyHSFreeArray(PPvoid_t PPJHS, PJError_t PJError);
DESCRIPTION¶
A macro equivalent exists for each function call. Because the macro forms are
sometimes faster and have a simpler error handling interface than the
equivalent functions, they are the preferred way of calling the JudyHS
functions. See
JudyHS(3) for more information. The function call
definitions are included here for completeness.
One of the difficulties in using the JudyHS function calls lies in determining
whether to pass a pointer or the address of a pointer. Since the functions
that modify the JudyHS array must also modify the pointer to the JudyHS array,
you must pass the address of the pointer rather than the pointer itself. This
often leads to hard-to-debug programmatic errors. In practice, the macros
allow the compiler to catch programming errors when pointers instead of
addresses of pointers are passed.
The JudyHS function calls have an additional parameter beyond those specified in
the macro calls. This parameter is either a pointer to an error structure, or
NULL (in which case the error information is not returned -- only
PJERR in the return parameter).
In the following descriptions, the functions are described in terms of how the
macros use them. This is the suggested use of the macros after your program
has been fully debugged. When the
JUDYERROR_NOTEST macro is not
specified, an error structure is declared to store error information returned
from the JudyHS functions when an error occurs.
Notice the placement of the
& in the different functions.
-
JudyHSIns(&PJHS, Index, Length, &JError)
-
#define JHSI(PValue, PJHS, Index) \
PValue = JudyLIns(&PJHS, Index, PJE0)
-
-
JudyHSDel(&PJHS, Index, Length, &JError)
-
#define JHSD(Rc_int, PJHS, Index, Length) \
Rc_int = JudyHSDel(&PJHS, Index, Length, PJE0)
-
-
JudyHSGet(PJHS, Index, Length)
-
#define JHSG(PValue, PJHS, Index, Length) \
PValue = JudyHSIns(PJHS, Index, Length)
-
-
JudyHSFreeArray(&PJHS, &JError)
-
#define JHSFA(Rc_word, PJHS) \
Rc_word = JudyHSFreeArray(&PJHS, PJE0)
-
Definitions for all the Judy functions, the types
Pvoid_t,
Pcvoid_t,
PPvoid_t,
Word_t ,
JError_t, and
PJError_t, the constants
NULL,
JU_ERRNO_*,
JERR,
PPJERR, and
PJE0 are provided in the
Judy.h header file
(/usr/include/Judy.h).
Note: Callers should define JudyHS arrays as
type
Pvoid_t, which can be passed by value to functions that take
Pcvoid_t (constant
Pvoid_t), and also by address to functions
that take
PPvoid_t.
The return type from most
JudyHS functions is
PPvoid_t so that the
values stored in the array can be pointers to other objects, which is a
typical usage, or cast to a
Word_t * when a pointer to a value is
required instead of a pointer to a pointer.
AUTHOR¶
JudyHS was invented and implemented by Doug Baskins after retiring -Packard.
SEE ALSO¶
Judy(3),
Judy1(3),
JudyL(3),
JudySL(3),
JudyHS(3),
malloc(),
the Judy website,
http://judy.sourceforge.net, for more information and
Application Notes.