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adx_util - Array Descriptor (ADX) Utilities

The ADX_UTIL package provides functions for creating and manipulating dynamically sized arrays of arbitrary, homogeneous (fixed-size) elements.

This package was inspired by my MDX_UTIL memory region descriptor package, which, in fact, did include the ability to treat a memory region as an array. However, the mechanisms for working with memory regions as arrays were awkward for the application using the package. Hopefully, ADX_UTIL improves on that front.

The following example reads a complete text file into an array of SDX_UTIL string descriptors, one element per line, a convenient framework for a simple text editor. Note that the array is composed of pointers (StringDx) to string descriptors (_StringDx), not an array of string descriptors themselves.

    #include  "adx_util.h"	-- Array Descriptor utilities.
    #include  "sdx_util.h"	-- String Descriptor utilities.

    FILE  *file ;
    ssize_t  count ;
    ArrayDx  adx ;
    StringDx  *element41, sdx ;

    adxCreate (0, sizeof (StringDx), NULL, 0, AdxDynamic, &adx) ;

    file = fopen ("example.txt", "r") ;
    for ( ; ; ) {			-- Break on EOF or error.
        sdxCreate (NULL, -1, SdxDynamic, &sdx) ;
        if (sdxReadLine (file, sdx, &count) || (count < 1))  break ;
        adxAdd (adx, (const void *) &sdx, 1, -1) ;
    fclose (file) ;

Then, access line 20. Note the distinction between line numbers, 1..N, and their corresponding array indices, 0..N-1 — hence all the little "-1"s in the few lines of code below; e.g., line 20 is at index 20-1 = 19.

    printf ("Line 20: \"%s\"\n",
            sdxStringZ (*((StringDx) adxGet (adx, 20-1)))) ;

Next, insert a line between line 30 and line 31.

    sdxCreate ("I'm the new line 31!!!", -1, SdxVolatile, &sdx) ;
    adxAdd (adx, (const void *) &sdx, 1, 31-1) ;

Now, delete lines 41-45. Since the elements have dynamically allocated resources of their own, it is necessary to destroy or save the elements being deleted before actually deleting them from the array.

    element41 = (StringDx *) adxGet (adx, 41-1) ;
					-- Destroy descriptors being deleted
    for (i = 0 ;  i < 5 ;  i++) {	-- (or save them in cut/undo buffer).
        sdxDestroy (element41[i]) ;
    adxDelete (adx, 5, 41-1) ;	-- Delete the 5 elements.

Public Procedures

adxAdd() - adds one or more elements to a described array.
adxCopy() - copy the contents of one array descriptor to another.
adxCount() - gets the number of elements in a described array.
adxCreate() - creates an array descriptor.
adxDelete() - deletes one or more elements from a described array.
adxDestroy() - destroys an array descriptor.
adxDuplicate() - duplicates an array descriptor.
adxElementSize() - gets the size in bytes of a described array's elements.
adxErase() - erases the contents of an array descriptor.
adxGet() - gets the address of an element in a described array.
adxIncrement() - sets or gets the block size used to expand an array.
adxOwn() - takes ownership of a described array.

Source Files


(See libgpl for the complete source, including support routines and build files.)

Alex Measday  /  E-mail