workbench/c/evalParser.y

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Bison file for the Eval grammar.
   6     Lang: English
   7 */
   8
   9 %{
  10 #define YYSTYPE  int
  11
  12 #include  <ctype.h>
  13 #include  <math.h>
  14 #include  <string.h>
  15 #include  <stdio.h>
  16
  17 char *text;
  18
  19 extern int yylval;
  20 extern void yyerror(char *s);
  21
  22 int g_result;
  23
  24 int yylex()
  25 {
  26     int c;
  27
  28     do
  29     {
  30         c = *text++;
  31     } while (c == ' ' || c == '\t');
  32
  33     if (c == '0')
  34     {
  35         switch (*text)
  36         {
  37         case 'x':
  38             sscanf(text + 1, "%x", &yylval);
  39
  40             text++;
  41
  42             while ((*text >= '0' && *text <= '9') ||
  43                    (*text >= 'a' && *text <= 'f') ||
  44                    (*text >= 'A' && *text <= 'F'))
  45             {
  46                 text++;
  47             }
  48
  49             return NUM;
  50
  51         case '0':
  52         case '1':
  53         case '2':
  54         case '3':
  55         case '4':
  56         case '5':
  57         case '6':
  58         case '7':
  59             sscanf(text - 1, "%o", &yylval);
  60
  61             while ((*text >= '0' && *text <= '7'))
  62             {
  63                 text++;
  64             }
  65
  66             return NUM;
  67
  68         case '8':
  69         case '9':
  70             /* Skip 08... and 09... constructions and let them be ordinary
  71                decimal stuff */
  72             break;
  73
  74         default:
  75             /* It was just the constant 0 */
  76             yylval = 0;
  77
  78             return NUM;
  79         }
  80
  81     }
  82
  83     if (c == '#')
  84     {
  85         int d = *text++;
  86
  87         if (d == 'x')
  88         {
  89             sscanf(text, "%x", &yylval);
  90
  91             while ((*text >= '0' && *text <= '9') ||
  92                    (*text >= 'a' && *text <= 'f') ||
  93                    (*text >= 'A' && *text <= 'F'))
  94             {
  95                 text++;
  96             }
  97
  98             return NUM;
  99         }
 100         else if (isdigit(d))
 101         {
 102             sscanf(text - 1, "%o", &yylval);
 103
 104             while ((*text >= '0' && *text <= '7'))
 105             {
 106                 text++;
 107             }
 108
 109             return NUM;
 110         }
 111         else
 112         {
 113             yyerror("Lexer error");
 114         }
 115     }
 116
 117
 118     if (c == '\'')
 119     {
 120         yylval = *text++;
 121
 122         return NUM;
 123     }
 124
 125     if (isdigit(c))
 126     {
 127         sscanf(text - 1, "%i", &yylval);
 128
 129         while (isdigit(*text))
 130         {
 131             text++;
 132         }
 133
 134         return NUM;
 135     }
 136
 137     if (isalpha(c))
 138     {
 139         int   i = 1;
 140         char *textCopy = text - 1;
 141
 142         while (isalpha(text[i]))
 143         {
 144             i++;
 145         }
 146
 147         text += i;
 148
 149         if (strncasecmp(textCopy, "m", i) == 0 ||
 150             strncmp(textCopy, "mod", i) == 0)
 151         {
 152             return '%';
 153         }
 154
 155         if (strncmp(textCopy, "xor", i) == 0 ||
 156             strncasecmp(textCopy, "x", i) == 0)
 157         {
 158             return 'x';
 159         }
 160
 161         if (strncmp(textCopy, "eqv", i) == 0 ||
 162             strncasecmp(textCopy, "e", i) == 0)
 163         {
 164             return 'e';
 165         }
 166
 167         if (strncmp(textCopy, "lsh", i) == 0 ||
 168             strncasecmp(textCopy, "l", i) == 0)
 169         {
 170             return 'l';
 171         }
 172
 173         if (strncmp(textCopy, "rsh", i) == 0 ||
 174             strncasecmp(textCopy, "r", i) == 0)
 175         {
 176             return 'r';
 177         }
 178
 179         yyerror("Lexing error");
 180     }
 181
 182     return c;
 183 }
 184
 185
 186 int intPow(int x, int y)
 187 {
 188     int result = 1;
 189
 190     while (y > 0)
 191     {
 192         result *= x;
 193         y--;
 194     }
 195
 196     return result;
 197 }
 198
 199
 200 void yyerror(char *s)
 201 {
 202     printf("%s\n", s);
 203 }
 204
 205
 206 %}
 207
 208 %token NUM
 209 %left 'l' 'r'
 210 %left 'e'
 211 %left '|'
 212 %left 'x'
 213 %left '&'
 214 %left '-' '+'
 215 %left '*' '/' '%'
 216 %left NEG '~'
 217 %right '^'
 218
 219 %%
 220
 221 val: expr
 222 {
 223     g_result = $1;
 224 }
 225 ;
 226
 227 expr: NUM                  { $$ = $1;         }
 228     | expr 'l' expr        { $$ = $1 << $3;   }
 229     | expr 'r' expr        { $$ = $1 >> $3;   }
 230     | expr 'e' expr        { $$ = ($1 & $3) | (~$1 & ~$3); }
 231     | expr '|' expr        { $$ = $1 | $3;    }
 232     | expr 'x' expr        { $$ = $1 ^ $3;    }
 233     | expr '&' expr        { $$ = $1 & $3;    }
 234     | expr '+' expr        { $$ = $1 + $3;    }
 235     | expr '-' expr        { $$ = $1 - $3;    }
 236     | expr '*' expr        { $$ = $1 * $3;    }
 237     | expr '/' expr        { $$ = $1 / $3;    }
 238     | expr '%' expr        { $$ = $1 % $3;    }
 239     | '-' expr  %prec NEG  { $$ = -$2;        }
 240     | '~' expr             { $$ = ~$2;        }
 241     | expr '^' expr        { $$ = intPow($1, $3); }
 242     | '(' expr ')'         { $$ = $2;         }
 243 ;
 244
 245 %%
 246
 247 #if 0
 248
 249 int main()
 250 {
 251
 252     text = "(1 lsh 4) mod 2";
 253
 254     if (yyparse() == 1)
 255     {
 256         printf("Parse error\n");
 257     }
 258     else
 259     {
 260         printf("The answer is %i\n", g_result);
 261     }
 262
 263     return 0;
 264 }
 265
 266 #endif