JudyL_funcs(3)

JudyL_funcs(3) — straight outta the Library Functions Manual, bestie 🫶✨

🌸 NAME 🌸

JudyL functions — a C library for creating and accessing a dynamic array of words, using any value of a word as an index. Periodt.

✨ SYNOPSIS ✨

Okay bestie, here's the full function-call lineup, copied exactly — every signature, every type, every comma:

       PPvoid_t JudyLIns(       PPvoid_t PPJLArray, Word_t    Index, PJError_t PJError);
       int      JudyLDel(       PPvoid_t PPJLArray, Word_t    Index, PJError_t PJError);
       PPvoid_t JudyLGet(       Pcvoid_t  PJLArray, Word_t    Index, PJError_t PJError);
       Word_t   JudyLCount(     Pcvoid_t  PJLArray, Word_t    Index1, Word_t    Index2, PJError_t PJError);
       PPvoid_t JudyLByCount(   Pcvoid_t  PJLArray, Word_t    Nth,  Word_t * PIndex,  PJError_t PJError);
       Word_t   JudyLFreeArray( PPvoid_t PPJLArray, PJError_t PJError);
       Word_t   JudyLMemUsed(   Pcvoid_t  PJLArray);
       PPvoid_t JudyLFirst(     Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
       PPvoid_t JudyLNext(      Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
       PPvoid_t JudyLLast(      Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
       PPvoid_t JudyLPrev(      Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
       int      JudyLFirstEmpty(Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
       int      JudyLNextEmpty( Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
       int      JudyLLastEmpty( Pcvoid_t  PJLArray, Word_t * PIndex, PJError_t PJError);
       int      JudyLPrevEmpty( Pcvoid_t  PJLArray, Word_t * PIndex, 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 JudyL functions. See JudyL(3) for more information. The function call definitions are included here for completeness. Yes, both flavors are in the group chat 💅

🙈 pointer vs. address-of-pointer (the classic trap)

One of the difficulties in using the JudyL function calls lies in determining whether to pass a pointer or the address of a pointer. Since the functions that modify the JudyL array must also modify the pointer to the JudyL 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.

🚨 lowkey important: for the modifying calls, hand over &PJLArray — the address of the pointer — not just PJLArray. That's the whole plot twist.

🫶 the extra error parameter

The JudyL 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 detailed error information is not returned).

💅 how these descriptions work (JUDYERROR_NOTEST)

In the following descriptions, the functions are described in terms of how the macros use them (only in the case of #define JUDYERROR_NOTEST 1). 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 JudyL functions when an error occurs.

👑 notice the placement of &

Notice the placement of the & in the different functions — it's giving very deliberate main character energy. Here's every call + macro pair, exactly as written:

• JudyLIns — notice the &PJLArray:

        JudyLIns(&PJLArray, Index, &JError)

                      #define JLI(PValue, PJLArray, Index)  \
                         PValue = JudyLIns(&PJLArray, Index, PJE0)

• JudyLDel — again, &PJLArray:

        JudyLDel(&PJLArray, Index, &JError)

                      #define JLD(Rc_int, PJLArray, Index)  \
                         Rc_int = JudyLDel(&PJLArray, Index, PJE0)

• JudyLGet — no & on PJLArray here:

        JudyLGet(PJLArray, Index, &JError)

                      #define JLG(PValue, PJLArray, Index)  \
                         PValue = JudyLGet(PJLArray, Index, PJE0)

• JudyLCount — PJLArray by value:

        JudyLCount(PJLArray, Index1, Index2, &JError)

                      #define JLC(Rc_word, PJLArray, Index1, Index2)  \
                         Rc_word = JudyLCount(PJLArray, Index1, Index2, PJE0)

• JudyLByCount — Nth in, &Index out:

        JudyLByCount(PJLArray, Nth, &Index, &JError)

                      #define JLBC(PValue, PJLArray, Nth, Index) \
                         PValue = JudyLByCount(PJLArray, Nth, &Index, PJE0)

• JudyLFreeArray — address of the pointer, because it's freeing the whole thing:

        JudyLFreeArray(&PJLArray, &JError)

                      #define JLFA(Rc_word, PJLArray) \
                         Rc_word = JudyLFreeArray(&PJLArray, PJE0)

• JudyLMemUsed — no error parameter, just vibes and memory numbers:

        JudyLMemUsed(PJLArray)

                      #define JLMU(Rc_word, PJLArray) \
                         Rc_word = JudyLMemUsed(PJLArray)

• JudyLFirst — &Index for the output index:

        JudyLFirst(PJLArray, &Index, &JError)

                      #define JLF(PValue, PJLArray, Index) \
                         PValue = JudyLFirst(PJLArray, &Index, PJEO)

• JudyLNext — same energy:

        JudyLNext(PJLArray, &Index, &JError)

                      #define JLN(PValue, PJLArray, Index) \
                         PValue = JudyLNext(PJLArray, &Index, PJEO)

• JudyLLast — same energy, but backwards-ish:

        JudyLLast(PJLArray, &Index, &JError)

                      #define JLL(PValue, PJLArray, Index) \
                         PValue = JudyLLast(PJLArray, &Index, PJEO)

• JudyLPrev — same energy, but definitely backwards:

        JudyLPrev(PJLArray, &Index, &JError)

                      #define JLP(PValue, PJLArray, Index) \
                         PValue = JudyLPrev(PJLArray, &Index, PJEO)

• JudyLFirstEmpty — empty-slot hunt begins:

        JudyLFirstEmpty(PJLArray, &Index, &JError)

                      #define JLFE(Rc_int, PJLArray, Index) \
                         Rc_int = JudyLFirstEmpty(PJLArray, &Index, PJEO)

• JudyLNextEmpty — next empty, coming through:

        JudyLNextEmpty(PJLArray, &Index, &JError)

                      #define JLNE(Rc_int, PJLArray, Index) \
                         Rc_int = JudyLNextEmpty(PJLArray, &Index, PJEO)

• JudyLLastEmpty — last empty, from the other end:

        JudyLLastEmpty(PJLArray, &Index, &JError)

                      #define JLLE(Rc_int, PJLArray, Index) \
                         Rc_int = JudyLLastEmpty(PJLArray, &Index, PJEO)

• JudyLPrevEmpty — prev empty, still on the hunt:

        JudyLPrevEmpty(PJLArray, &Index, &JError)

                      #define JLPE(Rc_int, PJLArray, Index) \
                         Rc_int = JudyLPrevEmpty(PJLArray, &Index, PJEO)

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 JudyL 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 JudyL 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 🍓

Judy was invented by Doug Baskins and implemented by Hewlett-Packard. Iconic collaboration, honestly 👑

🌈 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.

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Sign-off time, bestie: this is JudyL_funcs(3) from the Library Functions Manual; the footer in this copy only gives that page name, with no separate version/date line, so consider this your cute ending. Byeee 🎀💖