JudyHS_funcs(3) JudyHS_funcs(3)

NAME
JudyHS functions - 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 from Hewlett-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.