variables.cpp

   1 //-----------------------------------------------------------------------------
   2 //
   3 //      Scan expr for vars, return in vector
   4 //
   5 //      Input:          Expression on stack
   6 //
   7 //      Output:         Vector
   8 //
   9 //-----------------------------------------------------------------------------
  10
  11 #include "stdafx.h"
  12 #include "defs.h"
  13 static void scan(U *);
  14 static int __cmp(const void *, const void *);
  15 static int h;
  16
  17 void
  18 variables(void)
  19 {
  20         int i, n;
  21         save();
  22         p1 = pop();
  23         h = tos;
  24         scan(p1);
  25         n = tos - h;
  26         if (n > 1)
  27                 qsort(stack + h, n, sizeof (U *), __cmp);
  28         p1 = alloc_tensor(n);
  29         p1->u.tensor->ndim = 1;
  30         p1->u.tensor->dim[0] = n;
  31         for (i = 0; i < n; i++)
  32                 p1->u.tensor->elem[i] = stack[i];
  33         tos = h;
  34         push(p1);
  35         restore();
  36 }
  37
  38 static void
  39 scan(U *p)
  40 {
  41         int i;
  42         if (iscons(p)) {
  43                 p = cdr(p);
  44                 while (iscons(p)) {
  45                         scan(car(p));
  46                         p = cdr(p);
  47                 }
  48         } else if (issymbol(p) && p != symbol(E)) {
  49                 for (i = h; i < tos; i++)
  50                         if (stack[i] == p)
  51                                 return;
  52                 push(p);
  53         }
  54 }
  55
  56 static int
  57 __cmp(const void *p1, const void *p2)
  58 {
  59         return cmp_expr(*((U **) p1), *((U **) p2));
  60 }