string.h

   1 global string_first;
   2
   3 constant STRING_NEXT 0;
   4 constant STRING_PTR 1;
   5 constant STRING_LEN 2;
   6 constant STRING_REF 3;
   7 constant STRING__SIZE (4*2);
   8
   9 ! Initialise the string store.
  10
  11 [ string_init;
  12         string_first = 0;
  13 ];
  14
  15 ! Returns false if the string is constant (i.e., it points to a literal in
  16 ! the byte-code itself).
  17
  18 [ string_isvar s;
  19         return ((s < store_bottom) || (s > store_eop));
  20 ];
  21
  22 ! Add an entry for a new string.
  23
  24 [ string_alloc str len  s;
  25         if (string_isvar(str))
  26         {
  27                 ! Need to duplicate the string.
  28                 s = mem_alloc(len);
  29                 memcpy(s, str, len);
  30                 str = s;
  31         }
  32         s = mem_alloc(STRING__SIZE);
  33         s-->STRING_NEXT = string_first;
  34         s-->STRING_PTR = str;
  35         s-->STRING_LEN = len;
  36         string_first = s;
  37         return s;
  38 ];
  39
  40 ! Print a string.
  41
  42 [ string_print s  i;
  43         i = s-->STRING_LEN;
  44         s = s-->STRING_PTR;
  45         while (i--)
  46                 print (char) (s++)->0;
  47 ];
  48
  49 ! Compare two strings.
  50
  51 [ string_compare s1 s2  i;
  52         i = s1-->STRING_LEN;
  53         if (i ~= s2-->STRING_LEN)
  54                 return -1;
  55         s1 = s1-->STRING_PTR;
  56         s2 = s2-->STRING_PTR;
  57         while (i--)
  58                 if ((s1++)->0 ~= (s2++)->0)
  59                         return -1;
  60         return 0;
  61 ];
  62
  63 ! Garbage collection: clean.
  64
  65 [ string_clean  s;
  66         s = string_first;
  67         while (s)
  68         {
  69                 s-->STRING_REF = 0;
  70                 s = s-->STRING_NEXT;
  71         }
  72 ];
  73
  74 ! Garbage collection: mark.
  75
  76 [ string_mark  var;
  77         var = store_firstvar;
  78         while (var)
  79         {
  80                 if (var-->VN_TYPE == TYPE_STRING)
  81                         var-->VN_VALUE-->STRING_REF = 1;
  82                 var = var-->VN_NEXT;
  83         }
  84 ];
  85
  86 #ifdef DEBUG;
  87 ! Garbage collection: list status.
  88
  89 [ string_status  s;
  90         s = string_first;
  91         while (s)
  92         {
  93                 print s, " ", s-->STRING_NEXT, " ";
  94                 string_print(s);
  95                 print " ", s-->STRING_REF, "^";
  96                 s = s-->STRING_NEXT;
  97         }
  98 ];
  99 #endif;
 100
 101 ! Garbage collection: sweep.
 102
 103 [ string_sweep  s olds news;
 104         olds = 0;
 105         s = string_first;
 106         while (s)
 107         {
 108                 news = s-->STRING_NEXT;
 109                 if (s-->STRING_REF == 0)
 110                 {
 111                         if (string_isvar(s-->STRING_PTR))
 112                                 mem_free(s-->STRING_PTR);
 113                         if (olds)
 114                                 olds-->STRING_NEXT = news;
 115                         else
 116                         {
 117                                 ! If olds is null, then we're on the first
 118                                 ! string in the list; which means we need to
 119                                 ! change string_first when we remove it.
 120                                 string_first = news;
 121                         }
 122                         mem_free(s);
 123                 }
 124                 else
 125                         olds = s;
 126
 127                 s = news;
 128         }
 129 ];
 130
 131 ! Garbage collector.
 132
 133 [ string_gc;
 134         ! Phase one: clean.
 135         string_clean();
 136         ! Phase two: mark.
 137         string_mark();
 138 #ifdef DEBUG;
 139         !string_status();
 140 #endif;
 141         ! Phase three: sweep.
 142         string_sweep();
 143 ];
 144
 145 ! Turn a string into an int.
 146
 147 [ string_toint s  len i neg;
 148         len = s-->STRING_LEN;
 149         s = s-->STRING_PTR;
 150         i = 0;
 151         neg = 1;
 152
 153         while (len && (s->0 == 32 or 9))
 154         {
 155                 s++;
 156                 len--;
 157         }
 158
 159         if (len == 0)
 160                 return i;
 161
 162         if (s->0 == '-')
 163         {
 164                 neg = -1;
 165                 s++;
 166                 len--;
 167         }
 168
 169         if (len == 0)
 170                 return i;
 171
 172         while (len && (s->0 >= '0') && (s->0 <= '9'))
 173         {
 174                 i = i*10 + (s->0 - '0');
 175                 s++;
 176                 len--;
 177         }
 178
 179         return i*neg;
 180 ];