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JudyL(3)                   Library Functions Manual                   JudyL(3)


NAME

       JudyL macros - C library for creating and accessing a dynamic array of
       words, using a word as an index.


SYNOPSIS

       cc [flags] sourcefiles -lJudy

       #include <Judy.h>

       int      Rc_int;                          // return code - integer
       Word_t   Rc_word;                         // return code - unsigned word
       Word_t   Index, Index1, Index2, Nth;
       PWord_t  PValue;                          // pointer to return value
       Pvoid_t PJLArray = (Pvoid_t) NULL;        // initialize JudyL array

       JLI( PValue,  PJLArray, Index);          // JudyLIns()
       JLD( Rc_int,  PJLArray, Index);          // JudyLDel()
       JLG( PValue,  PJLArray, Index);          // JudyLGet()
       JLC( Rc_word, PJLArray, Index1, Index2); // JudyLCount()
       JLBC(PValue,  PJLArray, Nth, Index);     // JudyLByCount()
       JLFA(Rc_word, PJLArray);                 // JudyLFreeArray()
       JLMU(Rc_word, PJLArray);                 // JudyLMemUsed()
       JLF( PValue,  PJLArray, Index);          // JudyLFirst()
       JLN( PValue,  PJLArray, Index);          // JudyLNext()
       JLL( PValue,  PJLArray, Index);          // JudyLLast()
       JLP( PValue,  PJLArray, Index);          // JudyLPrev()
       JLFE(Rc_int,  PJLArray, Index);          // JudyLFirstEmpty()
       JLNE(Rc_int,  PJLArray, Index);          // JudyLNextEmpty()
       JLLE(Rc_int,  PJLArray, Index);          // JudyLLastEmpty()
       JLPE(Rc_int,  PJLArray, Index);          // JudyLPrevEmpty()


DESCRIPTION

       A JudyL array is the equivalent of an array of word-sized values.  A
       Value is addressed by an Index (key).  The array may be sparse, and the
       Index may be any word-sized number.  Memory to support the array is
       allocated as index/value pairs are inserted, and released as
       index/value pairs are deleted.  A JudyL array can also be thought of as
       a mapper, that is "map" a word to another word/pointer.

       As with an ordinary array, there are no duplicate indexes in a JudyL
       array.

       The value may be used as a scalar, or a pointer to a structure or block
       of data (or even another Judy array).

       A JudyL array is allocated with a NULL pointer

       Pvoid_t PJLArray = (Pvoid_t) NULL;

       Using the macros described here, rather than the JudyL function calls,
       the default error handling sends a message to the standard error and
       terminates the program with exit(1);.  For other error handling
       methods, see the ERRORS section.  JLI( PValue,  PJLArray, Index);
       // JudyLIns()

       Because the macro forms are sometimes faster and have a simpler error
       handling interface than the equivalent JudyL functions, they are the
       preferred way of calling the JudyL functions.

        JLI(PValue, PJLArray, Index) // JudyLIns()
                      Insert an Index and Value into the JudyL array PJLArray.
                      If the Index is successfully inserted, the Value is
                      initialized to 0. If the Index was already present, the
                      Value is not modified.

                      Return PValue pointing to Value.  Your program can use
                      this pointer to read or modify Value until the next
                      JLI() (insert), JLD() (delete) or JLFA() (freearray) is
                      executed on PJLArray. Examples:

                      *PValue = 1234;
                      Value = *PValue;

                      Return PValue set to PJERR if a malloc() fail occured.
                      Note: JLI() and JLD() reorganize the JudyL array.
                      Therefore, PValue returned from previous JudyL calls
                      become invalid and must be re-acquired.

        JLD(Rc_int, PJLArray, Index) // JudyLDel()
                      Delete the Index/Value pair from the JudyL array.

                      Return Rc_int set to 1 if successful.  Return Rc_int set
                      to 0 if Index was not present.  Return Rc_int set to
                      JERR if a malloc() fail occured.

        JLG(PValue, PJLArray, Index) // JudyLGet()
                      Get the pointer PValue associated with Index in the
                      PJLArray Judy array.

                      Return PValue pointing to Value.  Return PValue set to
                      NULL if the Index was not present.  Return PValue set to
                      PJERR if a malloc() fail occured.

        JLC(Rc_word, PJLArray, Index1, Index2) // JudyLCount()
                      Count the number of indexes present in the JudyL array
                      PJLArray between Index1 and Index2 (inclusive).

                      Return Rc_word set to the count.  A return value of 0
                      can be valid as a count.

                      To count all indexes present in a JudyL array, use:

                      JLC(Rc_word, PJLArray, 0, -1);

        JLBC(PValue, PJLArray, Nth, Index) // JudyLByCount()
                      Locate the Nth index that is present in the JudyL array
                      PJLArray (Nth = 1 returns the first index present).

                      Return PValue pointing to its Value and Index set to the
                      Nth index if found, otherwise return PValue set to NULL
                      (the value of Index is undefined).

        JLFA(Rc_word, PJLArray) // JudyLFreeArray()
                      Given a pointer to a JudyL array, free the entire array
                      (much faster than using a JLN(), JLD() loop).

                      Return Rc_word set to the number of bytes freed and
                      PJLArray set to NULL.

        JLMU(Rc_word, PJLArray) // JudyLMemUsed()
                      Return Rc_word set to the number of bytes of memory
                      malloc()'ed by PJLArray.  This is a very fast routine,
                      and may be used before and after a JLI() or JLD() call
                      with little performance impact.

        JudyL Search Functions
                      JLF(), JLN(), JLL(), JLP() allow you to search for
                      indexes in the array.  You may search inclusively or
                      exclusively, in either forward or reverse directions.
                      If successful, Index is returned set to the found index,
                      and PValue is returned set to a pointer to Index's
                      Value.  If unsuccessful, PValue is returned set to NULL,
                      and Index contains no useful information.  PValue must
                      be tested for non-NULL prior to using Index, since a
                      search failure is possible.

                      JLFE(), JLNE(), JLLE(), JLPE() allow you to search for
                      indexes that are not present ("empty") in the array.
                      You may search inclusively or exclusively, in either
                      forward or reverse directions.  If successful, Index is
                      returned set to a not present ("empty") index, and
                      Rc_int is returned set to 1.  If unsuccessful, Rc_int is
                      returned set to 0, and and Index contains no useful
                      information.  Rc_int must be checked prior to using
                      Index, since a search failure is possible.

        JLF(PValue, PJLArray, Index) // JudyLFirst()
                      Search (inclusive) for the first index present that is
                      equal to or greater than the passed Index.  (Start with
                      Index = 0 to find the first index in the array.)  JLF()
                      is typically used to begin a sorted-order scan of the
                      indexes present in a JudyL array.

        JLN(PValue, PJLArray, Index) // JudyLNext()
                      Search (exclusive) for the next index present that is
                      greater than the passed Index.  JLN() is typically used
                      to continue a sorted-order scan of the indexes present
                      in a JudyL array, or to locate a "neighbor" of a given
                      index.

        JLL(PValue, PJLArray, Index) // JudyLLast()
                      Search (inclusive) for the last index present that is
                      equal to or less than the passed Index.  (Start with
                      Index = -1, that is, all ones, to find the last index in
                      the array.)  JLL() is typically used to begin a reverse-
                      sorted-order scan of the indexes present in a JudyL
                      array.

        JLP(PValue, PJLArray, Index) // JudyLPrev()
                      Search (exclusive) for the previous index present that
                      is less than the passed Index.  JLP() is typically used
                      to continue a reverse-sorted-order scan of the indexes
                      present in a JudyL array, or to locate a "neighbor" of a
                      given index.

        JLFE(Rc_int, PJLArray, Index) // JudyLFirstEmpty()
                      Search (inclusive) for the first index absent that is
                      equal to or greater than the passed Index.  (Start with
                      Index = 0 to find the first index absent in the array.)

        JLNE(Rc_int, PJLArray, Index) // JudyLNextEmpty()
                      Search (exclusive) for the next index absent that is
                      greater than the passed Index.

        JLLE(Rc_int, PJLArray, Index) // JudyLLastEmpty()
                      Search (inclusive) for the last index absent that is
                      equal to or less than the passed Index.  (Start with
                      Index = -1, that is, all ones, to find the last index
                      absent in the array.)

        JLPE(Rc_int, PJLArray, Index) // JudyLPrevEmpty()
                      Search (exclusive) for the previous index absent that is
                      less than the passed Index.


Multi-dimensional JudyL Arrays

       Storing a pointer to another JudyL array in a JudyL array's Value is a
       simple way to support dynamic multi-dimensional arrays.  These arrays
       (or trees) built using JudyL arrays are very fast and memory efficient.
       (In fact, that is how JudySL and JudyHS are implemented).  An arbitrary
       number of dimensions can be realized this way.  To terminate the number
       of dimensions (or tree), the Value pointer is marked to NOT point to
       another Judy array. A JLAP_INVALID flag is used in the least
       significant bit(s) of the pointer.  After the flag JLAP_INVALID is
       removed, it is used as a pointer to the users data.  The Judy.h header
       file defines JLAP_INVALID.  See code fragment below.

       Note: The current version of Judy.h changed this flag from 0x4 to 0x1
       to allow for a malloc() that does not deliver memory on an 8 byte
       aligned boundry (such as old versions of valgrind).

       The following example code segment can be used to determine whether or
       not a pointer points to another JudyL:

       PValue = (PWord_t)PMultiDimArray;

       for (Dim = 0; ;Dim++)
       {
          if (PValue == (PWord_t)NULL) goto IndexNotFound;

          /* Advance to next dimension in array */
          JLG(PValue, (Pvoid_t)*PValue, Index[Dim]);

          /* Check if pointer to user buffer: */
          if (*PValue & JLAP_INVALID)) break;
       }
       UPointer = (UPointer_t) (*PValue & ~JLAP_INVALID);  // mask and cast.
       printf("User object pointer is 0x%lx\n", (Word_t) UPointer);
              ...

       Note:  This works because malloc() guarantees to return a pointer with
       the least bit(s) == 0x0.  You must remove JLAP_INVALID before using the
       pointer.


ERRORS: See: Judy_3.htm#ERRORS


EXAMPLE

       Read a series of index/value pairs from the standard input, store in a
       JudyL array, and then print out in sorted order.

       #include <stdio.h>
       #include <Judy.h>

       Word_t   Index;                     // array index
       Word_t   Value;                     // array element value
       Word_t * PValue;                    // pointer to array element value
       int      Rc_int;                    // return code

       Pvoid_t  PJLArray = (Pvoid_t) NULL; // initialize JudyL array

       while (scanf("%lu %lu", &Index, &Value))
       {
           JLI(PValue, PJLArray, Index);
           If (PValue == PJERR) goto process_malloc_failure;
           *PValue = Value;                 // store new value
       }
       // Next, visit all the stored indexes in sorted order, first ascending,
       // then descending, and delete each index during the descending pass.

       Index = 0;
       JLF(PValue, PJLArray, Index);
       while (PValue != NULL)
       {
           printf("%lu %lu\n", Index, *PValue));
           JLN(PValue, PJLArray, Index);
       }

       Index = -1;
       JLL(PValue, PJLArray, Index);
       while (PValue != NULL)
       {
           printf("%lu %lu\n", Index, *PValue));

           JLD(Rc_int, PJLArray, Index);
           if (Rc_int == JERR) goto process_malloc_failure;

           JLP(PValue, PJLArray, Index);
       }


AUTHOR

       Judy was invented by Doug Baskins and implemented by Hewlett-Packard.


SEE ALSO

       Judy(3), Judy1(3), JudySL(3), JudyHS(3),
       malloc(),
       http://judy.sourceforge.net, for more information and Application
       Notes.

                                                                      JudyL(3)

judy 1.0.5 - Generated Sun Nov 12 16:50:17 CST 2023
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