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 static void yyerror(char *s);
  21 static int intPow(int x, int y);
  22 static int yylex();
  23
  24 int g_result;
  25
  26 %}
  27
  28 %token NUM
  29 %left 'l' 'r'
  30 %left 'e'
  31 %left '|'
  32 %left 'x'
  33 %left '&'
  34 %left '-' '+'
  35 %left '*' '/' '%'
  36 %left NEG '~'
  37 %right '^'
  38
  39
  40 %%
  41
  42 val: expr
  43 {
  44     g_result = $1;
  45 }
  46 ;
  47
  48 expr: NUM                  { $$ = $1;         }
  49     | expr 'l' expr        { $$ = $1 << $3;   }
  50     | expr 'r' expr        { $$ = $1 >> $3;   }
  51     | expr 'e' expr        { $$ = ($1 & $3) | (~$1 & ~$3); }
  52     | expr '|' expr        { $$ = $1 | $3;    }
  53     | expr 'x' expr        { $$ = $1 ^ $3;    }
  54     | expr '&' expr        { $$ = $1 & $3;    }
  55     | expr '+' expr        { $$ = $1 + $3;    }
  56     | expr '-' expr        { $$ = $1 - $3;    }
  57     | expr '*' expr        { $$ = $1 * $3;    }
  58     | expr '/' expr        { $$ = $1 / $3;    }
  59     | expr '%' expr        { $$ = $1 % $3;    }
  60     | '-' expr  %prec NEG  { $$ = -$2;        }
  61     | '~' expr             { $$ = ~$2;        }
  62     | expr '^' expr        { $$ = intPow($1, $3); }
  63     | '(' expr ')'         { $$ = $2;         }
  64 ;
  65
  66 %%
  67
  68 static int yylex()
  69 {
  70     int c;
  71
  72     do
  73     {
  74         c = *text++;
  75     } while (c == ' ' || c == '\t');
  76
  77     if (c == '0')
  78     {
  79         switch (*text)
  80         {
  81         case 'x':
  82             sscanf(text + 1, "%x", &yylval);
  83
  84             text++;
  85
  86             while ((*text >= '0' && *text <= '9') ||
  87                    (*text >= 'a' && *text <= 'f') ||
  88                    (*text >= 'A' && *text <= 'F'))
  89             {
  90                 text++;
  91             }
  92
  93             return NUM;
  94
  95         case '0':
  96         case '1':
  97         case '2':
  98         case '3':
  99         case '4':
 100         case '5':
 101         case '6':
 102         case '7':
 103             sscanf(text - 1, "%o", &yylval);
 104
 105             while ((*text >= '0' && *text <= '7'))
 106             {
 107                 text++;
 108             }
 109
 110             return NUM;
 111
 112         case '8':
 113         case '9':
 114             /* Skip 08... and 09... constructions and let them be ordinary
 115                decimal stuff */
 116             break;
 117
 118         default:
 119             /* It was just the constant 0 */
 120             yylval = 0;
 121
 122             return NUM;
 123         }
 124
 125     }
 126
 127     if (c == '#')
 128     {
 129         int d = *text++;
 130
 131         if (d == 'x')
 132         {
 133             sscanf(text, "%x", &yylval);
 134
 135             while ((*text >= '0' && *text <= '9') ||
 136                    (*text >= 'a' && *text <= 'f') ||
 137                    (*text >= 'A' && *text <= 'F'))
 138             {
 139                 text++;
 140             }
 141
 142             return NUM;
 143         }
 144         else if (isdigit(d))
 145         {
 146             sscanf(text - 1, "%o", &yylval);
 147
 148             while ((*text >= '0' && *text <= '7'))
 149             {
 150                 text++;
 151             }
 152
 153             return NUM;
 154         }
 155         else
 156         {
 157             yyerror("Lexer error");
 158         }
 159     }
 160
 161
 162     if (c == '\'')
 163     {
 164         yylval = *text++;
 165
 166         return NUM;
 167     }
 168
 169     if (isdigit(c))
 170     {
 171         sscanf(text - 1, "%i", &yylval);
 172
 173         while (isdigit(*text))
 174         {
 175             text++;
 176         }
 177
 178         return NUM;
 179     }
 180
 181     if (isalpha(c))
 182     {
 183         int   i = 1;
 184         char *textCopy = text - 1;
 185
 186         while (isalpha(text[i]))
 187         {
 188             i++;
 189         }
 190
 191         text += i;
 192
 193         if (strncasecmp(textCopy, "m", i) == 0 ||
 194             strncmp(textCopy, "mod", i) == 0)
 195         {
 196             return '%';
 197         }
 198
 199         if (strncmp(textCopy, "xor", i) == 0 ||
 200             strncasecmp(textCopy, "x", i) == 0)
 201         {
 202             return 'x';
 203         }
 204
 205         if (strncmp(textCopy, "eqv", i) == 0 ||
 206             strncasecmp(textCopy, "e", i) == 0)
 207         {
 208             return 'e';
 209         }
 210
 211         if (strncmp(textCopy, "lsh", i) == 0 ||
 212             strncasecmp(textCopy, "l", i) == 0)
 213         {
 214             return 'l';
 215         }
 216
 217         if (strncmp(textCopy, "rsh", i) == 0 ||
 218             strncasecmp(textCopy, "r", i) == 0)
 219         {
 220             return 'r';
 221         }
 222
 223         yyerror("Lexing error");
 224     }
 225
 226     return c;
 227 }
 228
 229
 230 static int intPow(int x, int y)
 231 {
 232     int result = 1;
 233
 234     while (y > 0)
 235     {
 236         result *= x;
 237         y--;
 238     }
 239
 240     return result;
 241 }
 242
 243
 244 static void yyerror(char *s)
 245 {
 246     printf("%s\n", s);
 247 }
 248
 249
 250 #if 0
 251
 252 int main()
 253 {
 254
 255     text = "(1 lsh 4) mod 2";
 256
 257     if (yyparse() == 1)
 258     {
 259         printf("Parse error\n");
 260     }
 261     else
 262     {
 263         printf("The answer is %i\n", g_result);
 264     }
 265
 266     return 0;
 267 }
 268
 269 #endif