Loop over multiple arrays simultaneously/C-Elaboration

<lang c>#include <stdio.h>

typedef struct closure {

   void (*f)( void *elem, void *data);
   void  *data;

} *Closure;

typedef struct listSpec{

   void (*print)(const void *);
   void *ary;
   int  count;
   size_t elem_size;

} *ListSpec;

1. define LIST_SPEC( pf,typ,aa) {pf, aa, (sizeof(aa)/sizeof(typ)), sizeof(typ) }

/* calls closure's function f for each element in list */ void DoForEach( Closure c, ListSpec aspec ) {

   int i;
   void *val_ptr;
   for (i=0, val_ptr=aspec->ary; i< aspec->count; i++) {
       (*c->f)(val_ptr, c->data);
        val_ptr = ((char *)val_ptr) + aspec->elem_size;
   }

}

/* Used to find the minimum array length of list of lists */ void FindMin( ListSpec *paspec, int *minCount ) {

   ListSpec aspec = *paspec;
   if (*minCount>aspec->count) *minCount = aspec->count;

}

/* prints an element of a list using the list's print function */ void PrintElement( ListSpec *paspec, int *indx ) {

   ListSpec aspec = *paspec;
   (*aspec->print)( ((char*)aspec->ary) + (*indx)*aspec->elem_size);

}

/* Loop Over multiple lists (a list of lists)*/ void LoopMultiple( ListSpec arrays) {

   int indx;
   int minCount = 100000;
   struct closure c1 = { &FindMin, &minCount };
   struct closure xclsr = { &PrintElement, &indx };
   DoForEach( &c1, arrays);
   printf("min count = %d\n", minCount);

   for (indx=0; indx<minCount; indx++) {
       DoForEach(&xclsr, arrays );
       printf("\n");
   }

}

/* Defining our Lists */

void PrintInt(const int *ival) { printf("%3d,", *ival); } int ary1[] = { 6,5,4,9,8,7 }; struct listSpec lspec1 = LIST_SPEC( &PrintInt, int, ary1 );

void PrintShort(const short *ival) { printf("%3d,", *ival); } short ary2[] = { 3, 66, 20, 15, 7, 22, 10 }; struct listSpec lspec2 = LIST_SPEC( &PrintShort , short, ary2 );

void PrintStrg(const char *const *strg ) { printf(" %s", *strg); } const char *ary3[] = {"Hello", "all", "you","good", "folks","out", "there" }; struct listSpec lspec3 = LIST_SPEC( &PrintStrg , const char *, ary3 );

void PrintLstSpec(const ListSpec *ls) { printf("not-implemented"); } ListSpec listList[] = { &lspec1, &lspec2, &lspec3 }; struct listSpec llSpec = LIST_SPEC(&PrintLstSpec, ListSpec, listList);

int main(int argc, char *argv[]) {

   LoopMultiple( &llSpec);
   return 0;

}</lang>