parser.c

   1 #include <malloc.h>
   2 #include <math.h>
   3 #include <stdlib.h>
   4
   5 #include "debug.h"
   6 #include "fdprintf.h"
   7
   8 #include "parser.h"
   9
  10 /* compare codes */
  11
  12 int codecmp (char *ref, char *str)
  13 {
  14     int sig;
  15
  16     while (*ref != '\0') {
  17         if (*ref == '\t') {
  18              sig = (*str == '.') ? -1 : ((*str >= '0') && (*str <= '9'));
  19         } else {
  20             sig = *str - *ref;
  21         }
  22         if (sig != 0) {
  23             return (sig > 0) ? 1 : -1;
  24         }
  25         str++;
  26         ref++;
  27     }
  28
  29     return 0;
  30 }
  31
  32 /* allocate new element */
  33
  34 element_t *newelement (func_t function, int nbops, int prio)
  35 {
  36     element_t *new = (element_t *) calloc (1, sizeof (element_t));
  37     if (new == NULL) {
  38         VERBOSE (ERROR, fdprintf (stdfderr, "can't allocate memory\n"));
  39         return NULL;
  40     }
  41     new->func = function;
  42     new->nbops = nbops;
  43     new->prio = prio;
  44
  45     return new;
  46 }
  47
  48 /* functions */
  49
  50 #define NB_OPERATORS 6
  51
  52 keyword_t operators[NB_OPERATORS] = {
  53     { "+\t", Add, 2, 1, 1},
  54     { "-\t", Sub, 2, 1, 1},
  55     { "*",   Mul, 2, 1, 2},
  56     { "/",   Div, 2, 1, 2},
  57     { "%",   Mod, 2, 1, 3},
  58     { "^",   Pow, 2, 1, 4}
  59 };
  60
  61 #define NB_FUNCTIONS 9
  62 keyword_t functions[NB_FUNCTIONS] = {
  63     { "sqrt", Sqr, 1, 4, 5},
  64     { "pow",  Pow, 2, 3, 5},
  65     { "cos",  Cos, 1, 3, 5},
  66     { "sin",  Sin, 1, 3, 5},
  67     { "atan", Atn, 1, 4, 5},
  68     { "exp",  Exp, 1, 3, 5},
  69     { "log",  Log, 1, 3, 5},
  70     { "quit", Qui, 0, 4, 5},
  71     { "help", Hel, 0, 4, 5}
  72 };
  73
  74 /* subparser function */
  75
  76 element_t *subparser (element_t **proot, char **pstr, func_t func, int nbops, int prio)
  77 {
  78     element_t *new = newelement (func, nbops, prio);
  79     if (new == NULL) {
  80         return ERROR_OP;
  81     }
  82     new->ops[0] = *proot;
  83     new->ops[1] = parser (*pstr, pstr, new->prio);
  84     if (new->ops[1] == ERROR_OP) {
  85         return ERROR_OP;
  86     }
  87     *proot = newelement (Val, 1, 5);
  88     if (*proot == ERROR_OP) {
  89         return ERROR_OP;
  90     }
  91     (*proot)->ops[0] = new;
  92
  93     return *proot;
  94 }
  95
  96 /* parser function */
  97
  98 element_t *parser (char *str, char **next, int prio)
  99 {
 100     element_t *root = NULL;
 101     int i;
 102
 103     VERBOSE (DEBUG, PRINTOUT ("Starting parsing\n"));
 104
 105     /* main loop */
 106     while (*str != '\0') {
 107         int found = 0;
 108         element_t *new = NULL;
 109         VERBOSE (INFO, PRINTOUT ("Processing: %s\n", str));
 110
 111         /* skip spaces and tabs */
 112
 113         if ((*str == ' ') || (*str == '\t')) {
 114             str++;
 115             continue;
 116         }
 117
 118         /* check for open bracket */
 119
 120         if (*str == '(') {
 121             VERBOSE (DEBUG, PRINTOUT ("start processing bracket\n"));
 122             if (root) {
 123                 do {
 124                     found = 0;
 125                     new = parser (str + 1, &str, 0);
 126                     if (new == ERROR_OP) {
 127                         return ERROR_OP;
 128                     }
 129                     for (i = 0; i < root->nbops; i++) {
 130                         if (root->ops[i] == NULL) {
 131                             root->ops[i] = new;
 132                             found = 1;
 133                             break;
 134                         }
 135                     }
 136                     if (!found) {
 137                         return ERROR_OP;
 138                     }
 139                 } while (*str == ',');
 140             } else {
 141                 root = newelement (Val, 1, 5);
 142                 if (root == NULL) {
 143                     return ERROR_OP;
 144                 }
 145                 new = parser (str + 1, &str, 0);
 146                 if ((new == ERROR_OP) || (*str == ',')) {
 147                     return ERROR_OP;
 148                 }
 149                 root->ops[0] = new;
 150             }
 151             str++;
 152             VERBOSE (DEBUG, PRINTOUT ("stop processing bracket\n"));
 153             continue;
 154         }
 155
 156         /* check for closing bracket or koma */
 157
 158         if ((*str == ')') || (*str == ',')) {
 159             if (next != NULL) {
 160                 *next = str;
 161             }
 162             return root;
 163         }
 164
 165         /* look for operators */
 166
 167         for (i = 0; i < NB_OPERATORS; i++) {
 168             keyword_t *operator = operators + i;
 169             if (codecmp (operator->keyword, str) == 0) {
 170                 VERBOSE (DEBUG, PRINTOUT ("start processing operator\n"));
 171                 if (root) {
 172                     if ((prio) && (prio > operator->prio)) {
 173                         VERBOSE (DEBUG, PRINTOUT ("stop because operator priority\n"));
 174                         *next = str;
 175                         return root;
 176                     }
 177                     str += operator->offset;
 178                     VERBOSE (INFO, PRINTOUT ("Oper: %d\n", operator->func));
 179                     if (subparser (&root, &str, operator->func, operator->nbops, operator->prio) == ERROR_OP) {
 180                         return ERROR_OP;
 181                     }
 182                 } else if (*str == '-') {
 183                     new = newelement (Sig, 1, 9);
 184                     if (new == NULL) {
 185                         return ERROR_OP;
 186                     }
 187                     root = new;
 188                 } else {
 189                     return ERROR_OP;
 190                 }
 191                 found = 1;
 192                 VERBOSE (DEBUG, PRINTOUT ("stop processing operator\n"));
 193                 break;
 194             }
 195         }
 196         if (found) {
 197             continue;
 198         }
 199
 200         /* look for functions */
 201
 202         for (i = 0; i < NB_FUNCTIONS; i++) {
 203             keyword_t *function = functions + i;
 204             if (codecmp (function->keyword, str) == 0) {
 205                 VERBOSE (DEBUG, PRINTOUT ("start processing function\n"));
 206                 if (root == NULL) {
 207                     VERBOSE (INFO, PRINTOUT ("Func: %d\n", function->func));
 208                     new = newelement (function->func, function->nbops, function->prio);
 209                     if (new == NULL) {
 210                         return ERROR_OP;
 211                     }
 212                     root = new;
 213                  } else {
 214                     return ERROR_OP;
 215                 }
 216                 str += function->offset;
 217                 found = 1;
 218                 VERBOSE (DEBUG, PRINTOUT ("stop processing function\n"));
 219                 break;
 220             }
 221         }
 222         if (found) {
 223             continue;
 224         }
 225
 226         /* look for number */
 227
 228         if (((*str >= '0') && (*str <= '9')) ||
 229             (*str == '.') || (*str == '+') || (*str == '-')) {
 230             VERBOSE (DEBUG, PRINTOUT ("start processing value\n"));
 231             char *pt;
 232             float value = strtof (str, &pt);
 233             VERBOSE (INFO, PRINTOUT ("Value: %f\n", value));
 234             if (str != pt) {
 235                 if (root == NULL) {
 236                     new = newelement (Val, 1, 5);
 237                     if (new == NULL) {
 238                         return ERROR_OP;
 239                     }
 240                     new->value = value;
 241                     root = new;
 242                     str = pt;
 243                 } else if (root->func == Val) {
 244                     if ((*str == '+') || (*str == '-')) {
 245                         if ((prio) && (prio > 1)) {
 246                             VERBOSE (DEBUG, PRINTOUT ("stop because operator priority\n"));
 247                             *next = str;
 248                             return root;
 249                         }
 250                         if (subparser (&root, &str, Add, 2, 1) == ERROR_OP) {
 251                             return ERROR_OP;
 252                         }
 253                     } else {
 254                         return ERROR_OP;
 255                     }
 256                 } else {
 257                     return ERROR_OP;
 258                 }
 259                 found = 1;
 260             }
 261             VERBOSE (DEBUG, PRINTOUT ("stop processing value\n"));
 262         }
 263
 264         /* error */
 265
 266         if (!found) {
 267             return ERROR_OP;
 268         }
 269
 270     }
 271
 272     if (next != NULL) {
 273         *next = str;
 274     }
 275     return root;
 276 }
 277
 278 /* print element tree */
 279
 280 void print_element (element_t *root, int level)
 281 {
 282     char *func = NULL;
 283     int i;
 284
 285     if ((root == NULL) || (root == ERROR_OP)) {
 286         return;
 287     }
 288
 289     for (i = 0; i < level; i++) {
 290         PRINTOUT (" ");
 291     }
 292
 293     switch (root->func) {
 294     case Val: func = "Value"; break;
 295     case Sig: func = "Sign"; break;
 296     case Add: func = "Addition"; break;
 297     case Sub: func = "Subtraction"; break;
 298     case Mul: func = "Multiplication"; break;
 299     case Div: func = "Division"; break;
 300     case Mod: func = "Modulo"; break;
 301     case Pow: func = "Power"; break;
 302     case Sqr: func = "Square Root"; break;
 303     case Cos: func = "Cosine"; break;
 304     case Sin: func = "Sine"; break;
 305     case Atn: func = "Arc Tangent"; break;
 306     case Log: func = "Logarithm"; break;
 307     case Exp: func = "Exponantial"; break;
 308     case Qui: func = "Quit"; break;
 309     case Hel: func = "Help"; break;
 310     }
 311
 312     PRINTOUT ("Function: %s\n", func);
 313
 314     if ((root->func == Val) && (root->ops[0] == NULL)) {
 315         for (i = 0; i < level; i++) {
 316             PRINTOUT (" ");
 317         }
 318         PRINTOUT ("value: %f\n", root->value);
 319     } else {
 320         for (i = 0; i < root->nbops; i++) {
 321             print_element (root->ops[i], level + 1);
 322         }
 323     }
 324 }
 325
 326 /* quit function */
 327
 328 void quit (void)
 329 {
 330     PRINTOUT ("bye\n");
 331     exit (0);
 332 }
 333
 334 /* help message */
 335
 336 void help (void)
 337 {
 338     PRINTOUT ("calc is a simple calculator\n\n");
 339     PRINTOUT ("supported operators:\n");
 340     PRINTOUT (" + - * / % ^\n\n");
 341     PRINTOUT ("supported functions:\n");
 342     PRINTOUT (" pow sqrt cos sin atan log exp\n\n");
 343     PRINTOUT ("miscellaneous functions:\n");
 344     PRINTOUT (" quit help\n");
 345 }
 346
 347 /* evaluate element tree */
 348
 349 #define MASK_SUB 0x1
 350 #define MASK_DIV 0x2
 351
 352 double evaluate_element (element_t *root, char mask)
 353 {
 354     double op0 = 0, op1 = 0;
 355     char nextmask = mask;
 356
 357     if ((root == NULL) || (root == ERROR_OP)) {
 358         VERBOSE (WARNING, PRINTOUT ("error while evaluating\n"));
 359         return 0;
 360     }
 361
 362     /* mask to manage sub operator sub and div */
 363     switch (root->func) {
 364     case Add:
 365         nextmask &= ~MASK_SUB;
 366         nextmask &= ~MASK_DIV;
 367         break;
 368     case Sub:
 369         nextmask |= MASK_SUB;
 370         nextmask &= ~MASK_DIV;
 371         break;
 372     case Mul:
 373         nextmask &= ~MASK_DIV;
 374         break;
 375     case Div:
 376         nextmask |= MASK_DIV;
 377         break;
 378     default:
 379         nextmask = mask;
 380     }
 381
 382     switch (root->func) {
 383     case Val:
 384     case Sig:
 385         op0 = (root->ops[0]) ? evaluate_element (root->ops[0], nextmask) : root->value;
 386         break;
 387     case Add:
 388     case Sub:
 389     case Mul:
 390     case Div:
 391     case Mod:
 392     case Pow:
 393         if (root->ops[1]) {
 394             op1 = evaluate_element (root->ops[1], nextmask);
 395         } else {
 396             VERBOSE (WARNING, PRINTOUT ("error while evaluating (op[1])\n"));
 397             return 0;
 398         }
 399         /* fallthrough */
 400     case Sqr:
 401     case Cos:
 402     case Sin:
 403     case Atn:
 404     case Log:
 405     case Exp:
 406         if (root->ops[0]) {
 407             op0 = evaluate_element (root->ops[0], 0);
 408         } else {
 409             VERBOSE (WARNING, PRINTOUT ("error while evaluating (op[0])\n"));
 410             return 0;
 411         }
 412         break;
 413     case Qui:
 414     case Hel:
 415         break;
 416     }
 417
 418     switch (root->func) {
 419     case Val: return op0;
 420     case Sig: return -op0;
 421     case Add: return ((mask & MASK_SUB) == 0) ? op0 + op1 : op0 - op1;
 422     case Sub: return ((mask & MASK_SUB) == 0) ? op0 - op1 : op0 + op1;
 423     case Mul: return ((mask & MASK_DIV) == 0) ? op0 * op1 : op0 / op1;
 424     case Div: return ((mask & MASK_DIV) == 0) ? op0 / op1 : op0 * op1;
 425     case Mod: return fmod (op0, op1);
 426     case Pow: return pow (op0, op1);
 427     case Sqr: return sqrt (op0);
 428     case Cos: return cos (op0);
 429     case Sin: return sin (op0);
 430     case Atn: return atan (op0);
 431     case Log: return log (op0);
 432     case Exp: return exp (op0);
 433     case Qui: quit (); break;
 434     case Hel: help (); break;
 435     }
 436
 437     return 0;
 438 }
 439
 440 /* vim: set ts=4 sw=4 et: */