parser.c

   1 #include <malloc.h>
   2 #include <math.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6
   7 #include "debug.h"
   8
   9 #include "parser.h"
  10
  11 /* global variables */
  12
  13 double answer = 0;
  14
  15 #define STORAGE_SIZE 10
  16 double storage[STORAGE_SIZE] = {0};
  17
  18 /* compare codes */
  19
  20 int codecmp (char *ref, char *str)
  21 {
  22     int sig;
  23
  24     while (*ref != '\0') {
  25         if (*ref == '\t') {
  26              sig = (*str == '.') ? -1 : ((*str >= '0') && (*str <= '9'));
  27         } else {
  28             sig = *str - *ref;
  29         }
  30         if (sig != 0) {
  31             return (sig > 0) ? 1 : -1;
  32         }
  33         str++;
  34         ref++;
  35     }
  36
  37     return 0;
  38 }
  39
  40 /* allocate new element */
  41
  42 element_t *newelement (func_t function, int nbops, int prio)
  43 {
  44     element_t *new = (element_t *) calloc (1, sizeof (element_t));
  45     if (new == NULL) {
  46         VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
  47         exit (1);
  48     }
  49     if (nbops) {
  50         new->ops = (element_t **) calloc (nbops, sizeof (element_t *));
  51         if (new->ops == NULL) {
  52             VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
  53             exit (1);
  54         }
  55     }
  56     new->func = function;
  57     new->nbops = nbops;
  58     new->prio = prio;
  59
  60     return new;
  61 }
  62
  63 /* desallocate element */
  64
  65 void delelement (element_t *root)
  66 {
  67     if ((root != NULL) && (root != ERROR_OP)) {
  68         int i;
  69         for (i = 0; i < root->nbops; i++) {
  70             if ((root->ops[i] != NULL) && (root->ops[i] != ERROR_OP)) {
  71                 delelement (root->ops[i]);
  72             }
  73         }
  74         if (root->nbops) {
  75             free (root->ops);
  76         }
  77         free (root);
  78     }
  79 }
  80
  81 /* duplicate element */
  82
  83 element_t *dupelement (element_t *root)
  84 {
  85     element_t *tmp = NULL;
  86     int i;
  87
  88     if ((root == NULL) || (root == ERROR_OP)) {
  89         return root;
  90     }
  91     tmp = newelement (root->func, root->nbops, root->prio);
  92     tmp->value = root->value;
  93     for (i = 0; i < root->nbops; i++) {
  94         tmp->ops[i] = dupelement (root->ops[i]);
  95     }
  96     return tmp;
  97 }
  98
  99 /* functions */
 100
 101 #define NB_OPERATORS 14
 102 keyword_t operators[NB_OPERATORS] = {
 103     { "+\t", Add, 2, 1, 1},
 104     { "-\t", Sub, 2, 1, 1},
 105     { "*",   Mul, 2, 1, 2},
 106     { "/",   Div, 2, 1, 2},
 107     { "%",   Mod, 2, 1, 3},
 108     { "^",   Pow, 2, 1, 4},
 109     { "==",  Equal, 2, 2, -1},
 110     { "!=",  Diff, 2, 2, -1},
 111     { ">=",  Ge, 2, 2, -1},
 112     { "<=",  Le, 2, 2, -1},
 113     { ">",   Gt, 2, 1, -1},
 114     { "<",   Lt, 2, 1, -1},
 115     { "&",   And, 2, 1, -2},
 116     { "|",   Or, 2, 1, -2}
 117 };
 118
 119 #define NB_FUNCTIONS 23
 120 keyword_t functions[NB_FUNCTIONS] = {
 121     { "sqrt", Sqr, 1, 4, 5},
 122     { "pow",  Pow, 2, 3, 5},
 123     { "cos",  Cos, 1, 3, 5},
 124     { "sin",  Sin, 1, 3, 5},
 125     { "tan",  Tan, 1, 3, 5},
 126     { "acos", Acos, 1, 4, 5},
 127     { "asin", Asin, 1, 4, 5},
 128     { "atan", Atan, 1, 4, 5},
 129     { "log",  Log, 1, 3, 5},
 130     { "exp",  Exp, 1, 3, 5},
 131     { "abs",  Abs, 1, 3, 5},
 132     { "floor", Floor, 1, 5, 5},
 133     { "ceil", Ceil, 1, 4, 5},
 134     { "sto",  Store, 2, 3, 5},
 135     { "rcl",  Recall, 1, 3, 5},
 136     { "inc",  Inc, 1, 3, 5},
 137     { "dec",  Dec, 1, 3, 5},
 138     { "disp", Disp, 0, 4, 9},
 139     { "quit", Quit, 0, 4, 9},
 140     { "help", Help, 0, 4, 9},
 141     { "!",    Not, 1, 1, 6},
 142     { "cond", Cond, 3, 4, 5},
 143     { "while", While, 2, 5, 5}
 144 };
 145
 146 #define NB_CONSTANTS 3
 147 keyword_t constants[NB_CONSTANTS] = {
 148     { "ans", Ans, 0, 3, 5},
 149     { "e",   E, 0, 1, 5},
 150     { "pi",  Pi, 0, 2, 5}
 151 };
 152
 153 /* subparser function */
 154
 155 element_t *subparser (element_t **proot, char **pstr, func_t func, int nbops, int prio)
 156 {
 157     element_t *new = newelement (func, nbops, prio);
 158     new->ops[0] = *proot;
 159     new->ops[1] = parser (*pstr, pstr, new->prio);
 160     if ((new->ops[1] == NULL) || ((new->ops[1] != ERROR_OP) && (new->ops[1]->prio == 9))) {
 161         delelement (new->ops[1]);
 162         new->ops[1] = ERROR_OP;
 163     }
 164     if (new->ops[1] == ERROR_OP) {
 165         delelement (new);
 166         *proot = NULL;
 167         return ERROR_OP;
 168     }
 169     *proot = newelement (Val, 1, 5);
 170     (*proot)->ops[0] = new;
 171
 172     return *proot;
 173 }
 174
 175 /* parser function */
 176
 177 element_t *parser (char *str, char **next, int prio)
 178 {
 179     element_t *root = NULL;
 180     int i;
 181
 182     VERBOSE (DEBUG, fprintf (stdout, "Starting parsing\n"));
 183
 184     /* main loop */
 185     while (*str != '\0') {
 186         int found = 0;
 187         element_t *new = NULL;
 188         VERBOSE (INFO, fprintf (stdout, "Processing: %s\n", str));
 189
 190         /* skip spaces and tabs */
 191
 192         if ((*str == ' ') || (*str == '\t')) {
 193             str++;
 194             continue;
 195         }
 196
 197         /* check for open brace */
 198
 199         if (*str == '{') {
 200             VERBOSE (DEBUG, fprintf (stdout, "start processing brace\n"));
 201             if (root != NULL) {
 202                 delelement (root);
 203                 return ERROR_OP;
 204             }
 205             element_t **prog = NULL;
 206             new = newelement (Prog, 0, 5);
 207             root = new;
 208             prog = &root;
 209
 210             do {
 211                 new = parser (str + 1, &str, 0);
 212                 if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
 213                     delelement (new);
 214                     new = ERROR_OP;
 215                 }
 216                 if (new == ERROR_OP) {
 217                     delelement (root);
 218                     return ERROR_OP;
 219                 }
 220                 element_t *newprog = newelement (Prog, (*prog)->nbops + 1, 5);
 221                 for (i = 0; i < (*prog)->nbops; i++) {
 222                     newprog->ops[i] = (*prog)->ops[i];
 223                     (*prog)->ops[i] = NULL;
 224                 }
 225                 newprog->ops[(*prog)->nbops] = new;
 226                 delelement (*prog);
 227                 (*prog) = newprog;
 228             } while (*str == ',');
 229
 230             if (*str != '}') {
 231                 delelement (root);
 232                 return ERROR_OP;
 233             }
 234             str++;
 235             VERBOSE (DEBUG, fprintf (stdout, "stop processing brace\n"));
 236             continue;
 237         }
 238
 239         /* check for open bracket */
 240
 241         if (*str == '(') {
 242             VERBOSE (DEBUG, fprintf (stdout, "start processing bracket\n"));
 243             if (root) {
 244                 do {
 245                     found = 0;
 246                     new = parser (str + 1, &str, 0);
 247                     if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
 248                         delelement (new);
 249                         new = ERROR_OP;
 250                     }
 251                     if ((new == NULL) || (new == ERROR_OP)) {
 252                         delelement (root);
 253                         return ERROR_OP;
 254                     }
 255                     for (i = 0; i < root->nbops; i++) {
 256                         if (root->ops[i] == NULL) {
 257                             root->ops[i] = new;
 258                             found = 1;
 259                             break;
 260                         }
 261                     }
 262                     if (!found) {
 263                         delelement (new);
 264                         delelement (root);
 265                         return ERROR_OP;
 266                     }
 267                 } while (*str == ',');
 268             } else {
 269                 root = newelement (Val, 1, 5);
 270                 new = parser (str + 1, &str, 0);
 271                 if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
 272                     delelement (new);
 273                     new = ERROR_OP;
 274                 }
 275                 if ((new == NULL) || (new == ERROR_OP) || (*str == ',')) {
 276                     delelement (new);
 277                     delelement (root);
 278                     return ERROR_OP;
 279                 }
 280                 root->ops[0] = new;
 281             }
 282             if (*str != ')') {
 283                 delelement (root);
 284                 return ERROR_OP;
 285             }
 286             str++;
 287             VERBOSE (DEBUG, fprintf (stdout, "stop processing bracket\n"));
 288             continue;
 289         }
 290
 291         /* check for closing bracket, closing brace or koma */
 292
 293         if ((*str == ')') || (*str == '}') || (*str == ',')) {
 294             if (prio == -9) {
 295                 delelement (root);
 296                 return ERROR_OP;
 297             }
 298             if (next != NULL) {
 299                 *next = str;
 300             }
 301             return root;
 302         }
 303
 304         /* look for operators */
 305
 306         for (i = 0; i < NB_OPERATORS; i++) {
 307             keyword_t *operator = operators + i;
 308             if (codecmp (operator->keyword, str) == 0) {
 309                 VERBOSE (DEBUG, fprintf (stdout, "start processing operator\n"));
 310                 if (root) {
 311                     if ((prio) && (prio > operator->prio)) {
 312                         VERBOSE (DEBUG, fprintf (stdout, "stop because operator priority\n"));
 313                         *next = str;
 314                         return root;
 315                     }
 316                     str += operator->offset;
 317                     VERBOSE (INFO, fprintf (stdout, "Oper: %d\n", operator->func));
 318                     if (subparser (&root, &str, operator->func, operator->nbops, operator->prio) == ERROR_OP) {
 319                         delelement (root);
 320                         return ERROR_OP;
 321                     }
 322                 } else if (*str == '-') {
 323                     root = newelement (Sig, 1, 9);
 324                 } else {
 325                     return ERROR_OP;
 326                 }
 327                 found = 1;
 328                 VERBOSE (DEBUG, fprintf (stdout, "stop processing operator\n"));
 329                 break;
 330             }
 331         }
 332         if (found) {
 333             continue;
 334         }
 335
 336         /* look for functions */
 337
 338         for (i = 0; i < NB_FUNCTIONS; i++) {
 339             keyword_t *function = functions + i;
 340             if (codecmp (function->keyword, str) == 0) {
 341                 VERBOSE (DEBUG, fprintf (stdout, "start processing function\n"));
 342                 if (root == NULL) {
 343                     VERBOSE (INFO, fprintf (stdout, "Func: %d\n", function->func));
 344                     root = newelement (function->func, function->nbops, function->prio);
 345                 } else {
 346                     delelement (root);
 347                     return ERROR_OP;
 348                 }
 349                 str += function->offset;
 350                 found = 1;
 351                 VERBOSE (DEBUG, fprintf (stdout, "stop processing function\n"));
 352                 break;
 353             }
 354         }
 355         if (found) {
 356             continue;
 357         }
 358
 359         /* look for constant */
 360
 361         for (i = 0; i < NB_CONSTANTS; i++) {
 362             keyword_t *constant = constants + i;
 363             if (codecmp (constant->keyword, str) == 0) {
 364                 VERBOSE (DEBUG, fprintf (stdout, "start processing constant\n"));
 365                 if (root == NULL) {
 366                     VERBOSE (INFO, fprintf (stdout, "Const: %d\n", constant->func));
 367                     root = newelement (constant->func, constant->nbops, constant->prio);
 368                 } else {
 369                     delelement (root);
 370                     return ERROR_OP;
 371                 }
 372                 str += constant->offset;
 373                 found = 1;
 374                 VERBOSE (DEBUG, fprintf (stdout, "stop processing constant\n"));
 375                 break;
 376             }
 377         }
 378         if (found) {
 379             continue;
 380         }
 381
 382         /* look for number */
 383
 384         if (((*str >= '0') && (*str <= '9')) ||
 385             (*str == '.') || (*str == '+') || (*str == '-')) {
 386             VERBOSE (DEBUG, fprintf (stdout, "start processing value\n"));
 387             char *pt;
 388             double value = strtod (str, &pt);
 389             VERBOSE (INFO, fprintf (stdout, "Value: %f\n", value));
 390             if (str != pt) {
 391                 if ((root == NULL) || (root->prio == 6)) {
 392                     new = newelement (Val, 1, 5);
 393                     new->value = value;
 394                     if (root == NULL) {
 395                         root = new;
 396                     } else {
 397                         for (i = 0; i < root->nbops; i++) {
 398                             if (root->ops[i] == NULL) {
 399                                 root->ops[i] = new;
 400                                 found = 1;
 401                                 break;
 402                             }
 403                         }
 404                         if (!found) {
 405                             delelement (new);
 406                             delelement (root);
 407                             return ERROR_OP;
 408                         }
 409                     }
 410                     str = pt;
 411                 } else if ((*str == '+') || (*str == '-')) {
 412                     if ((prio) && (prio > 1)) {
 413                         VERBOSE (DEBUG, fprintf (stdout, "stop because operator priority\n"));
 414                         *next = str;
 415                         return root;
 416                     }
 417                     if (subparser (&root, &str, Add, 2, 1) == ERROR_OP) {
 418                         delelement (root);
 419                         return ERROR_OP;
 420                     }
 421                 } else {
 422                     delelement (root);
 423                     return ERROR_OP;
 424                 }
 425                 found = 1;
 426             }
 427             VERBOSE (DEBUG, fprintf (stdout, "stop processing value\n"));
 428         }
 429
 430         /* error */
 431
 432         if (!found) {
 433             delelement (root);
 434             return ERROR_OP;
 435         }
 436
 437     }
 438
 439     if (next != NULL) {
 440         *next = str;
 441     }
 442
 443     return root;
 444 }
 445
 446 /* print element tree */
 447
 448 void print_element (element_t *root, int level)
 449 {
 450     char *func = NULL;
 451     int i;
 452
 453     if ((root == NULL) || (root == ERROR_OP)) {
 454         return;
 455     }
 456
 457     for (i = 0; i < level; i++) {
 458         fprintf (stdout, " ");
 459     }
 460
 461     switch (root->func) {
 462     case Val: func = "Value"; break;
 463     case Sig: func = "Sign"; break;
 464     case Add: func = "Addition"; break;
 465     case Sub: func = "Subtraction"; break;
 466     case Mul: func = "Multiplication"; break;
 467     case Div: func = "Division"; break;
 468     case Mod: func = "Modulo"; break;
 469     case Pow: func = "Power"; break;
 470     case Sqr: func = "Square Root"; break;
 471     case Cos: func = "Cosine"; break;
 472     case Sin: func = "Sine"; break;
 473     case Tan: func = "Tangent"; break;
 474     case Acos: func = "Arc Cosine"; break;
 475     case Asin: func = "Arc Sine"; break;
 476     case Atan: func = "Arc Tangent"; break;
 477     case Log: func = "Logarithm"; break;
 478     case Exp: func = "Exponantial"; break;
 479     case Abs: func = "Absolute value"; break;
 480     case Ceil: func = "Ceil value"; break;
 481     case Floor: func = "Floor value"; break;
 482     case Store: func = "Store"; break;
 483     case Recall: func = "Recall"; break;
 484     case Inc: func = "Increase"; break;
 485     case Dec: func = "Decrease"; break;
 486     case Disp: func = "Display"; break;
 487     case Quit: func = "Quit"; break;
 488     case Help: func = "Help"; break;
 489     case Ans: func = "Ans"; break;
 490     case Pi: func = "Pi"; break;
 491     case E: func = "E"; break;
 492     case Equal: func = "Equal"; break;
 493     case Diff: func = "Different"; break;
 494     case Ge: func = "Greater or equal"; break;
 495     case Le: func = "Lesser or equal"; break;
 496     case Gt: func = "Greater"; break;
 497     case Lt: func = "Lesser"; break;
 498     case And: func = "And"; break;
 499     case Or: func = "Or"; break;
 500     case Not: func = "Not"; break;
 501     case Cond: func = "Condition"; break;
 502     case While: func = "While"; break;
 503     case Prog: func = "Program"; break;
 504     }
 505
 506     fprintf (stdout, "Function: %s\n", func);
 507
 508     if ((root->func == Val) && (root->ops[0] == NULL)) {
 509         for (i = 0; i < level; i++) {
 510             fprintf (stdout, " ");
 511         }
 512         fprintf (stdout, "value: %f\n", root->value);
 513     } else {
 514         for (i = 0; i < root->nbops; i++) {
 515             print_element (root->ops[i], level + 1);
 516         }
 517     }
 518 }
 519
 520 /* storage functions */
 521
 522 double store (int index, double value)
 523 {
 524     if ((index > 0) && (index <= STORAGE_SIZE)) {
 525         storage[index - 1] = value;
 526     } else {
 527         VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [1, %d]\n", index, STORAGE_SIZE));
 528     }
 529     return value;
 530 }
 531
 532 double recall (int index)
 533 {
 534     if ((index > 0) && (index <= STORAGE_SIZE)) {
 535         return storage[index - 1];
 536     } else {
 537         VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [1, %d]\n", index, STORAGE_SIZE));
 538     }
 539     return 0;
 540 }
 541
 542 double increase (int index)
 543 {
 544     if ((index > 0) && (index <= STORAGE_SIZE)) {
 545         return storage[index - 1]++;
 546     } else {
 547         VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [1, %d]\n", index, STORAGE_SIZE));
 548     }
 549     return 0;
 550 }
 551
 552 double decrease (int index)
 553 {
 554     if ((index > 0) && (index <= STORAGE_SIZE)) {
 555         return storage[index - 1]--;
 556     } else {
 557         VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [1, %d]\n", index, STORAGE_SIZE));
 558     }
 559     return 0;
 560 }
 561
 562 void display (void)
 563 {
 564     int i;
 565     fprintf (stdout, "storage:");
 566     for (i = 0; i < STORAGE_SIZE; i++) {
 567         fprintf (stdout, " %g", storage[i]);
 568     }
 569     fprintf (stdout, "\n");
 570 }
 571
 572 /* While do function */
 573
 574 double while_do (element_t *cond, element_t *action)
 575 {
 576     double ret = 0;
 577     element_t *temp = NULL;
 578
 579     VERBOSE (DEBUG, fprintf (stdout, "starting while loop\n"));
 580     while (1) {
 581         VERBOSE (DEBUG, fprintf (stdout, "loop...\n"));
 582
 583         temp = dupelement (cond);
 584         if (!evaluate_element (temp, 0)) {
 585             break;
 586         }
 587         if (action) {
 588             temp = dupelement (action);
 589             ret = evaluate_element (temp, 0);
 590         }
 591     }
 592
 593     VERBOSE (DEBUG, fprintf (stdout, "ending while loop\n"));
 594
 595     return ret;
 596 }
 597
 598 /* program function */
 599
 600 double program_do (element_t **prog, int nbcalls)
 601 {
 602     double ret = 0;
 603     int i;
 604     for (i = 0; i < nbcalls; i++) {
 605         ret = evaluate_element (prog[i], 0);
 606         prog[i] = NULL;
 607     }
 608     return ret;
 609 }
 610
 611 /* quit function */
 612
 613 void quit (void)
 614 {
 615     fprintf (stdout, "bye\n");
 616     exit (0);
 617 }
 618
 619 /* help message */
 620
 621 void help (void)
 622 {
 623     fprintf (stdout, "calc is a simple calculator\n\n");
 624     fprintf (stdout, "supported operators:");
 625     fprintf (stdout, " + - * / %% ^\n");
 626     fprintf (stdout, "camparison operators:");
 627     fprintf (stdout, " == != >= <= > <\n");
 628     fprintf (stdout, "logical operators:");
 629     fprintf (stdout, " & | !\n");
 630     fprintf (stdout, "mathematic functions:");
 631     fprintf (stdout, " pow sqrt log exp\n");
 632     fprintf (stdout, "trigonometric functions:");
 633     fprintf (stdout, " cos sin tan acos asin atan\n");
 634     fprintf (stdout, "supported functions:");
 635     fprintf (stdout, " abs ceil floor\n");
 636     fprintf (stdout, "storage functions:");
 637     fprintf (stdout, " sto rcl inc dec\n");
 638     fprintf (stdout, "conditional functions:");
 639     fprintf (stdout, " cond while\n");
 640     fprintf (stdout, "miscellaneous functions:");
 641     fprintf (stdout, " quit help\n");
 642     fprintf (stdout, "supported constants:");
 643     fprintf (stdout, " e pi\n");
 644 }
 645
 646 /* evaluate element tree */
 647
 648 #define MASK_SUB 0x1
 649 #define MASK_DIV 0x2
 650
 651 double evaluate_element (element_t *root, char mask)
 652 {
 653     double op0 = 0, op1 = 0;
 654     char nextmask = mask;
 655
 656     if ((root == NULL) || (root == ERROR_OP)) {
 657         VERBOSE (WARNING, fprintf (stdout, "error while evaluating\n"));
 658         return 0;
 659     }
 660
 661     /* mask to manage sub operator sub and div */
 662     switch (root->func) {
 663     case Add:
 664         nextmask &= ~MASK_SUB;
 665         nextmask &= ~MASK_DIV;
 666         break;
 667     case Sub:
 668         nextmask |= MASK_SUB;
 669         nextmask &= ~MASK_DIV;
 670         break;
 671     case Mul:
 672         nextmask &= ~MASK_DIV;
 673         break;
 674     case Div:
 675         nextmask |= MASK_DIV;
 676         break;
 677     default:
 678         nextmask = mask;
 679     }
 680
 681     switch (root->func) {
 682     case Val:
 683     case Sig:
 684         op0 = (root->ops[0]) ? evaluate_element (root->ops[0], nextmask) : root->value;
 685         break;
 686     case Add:
 687     case Sub:
 688     case Mul:
 689     case Div:
 690     case Mod:
 691     case Pow:
 692     case Store:
 693     case Equal:
 694     case Diff:
 695     case Ge:
 696     case Le:
 697     case Gt:
 698     case Lt:
 699     case And:
 700     case Or:
 701         if (root->ops[1]) {
 702             op1 = evaluate_element (root->ops[1], nextmask);
 703         } else if (root->func != Store) {
 704             VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[1])\n"));
 705             return 0;
 706         }
 707         /* fallthrough */
 708     case Sqr:
 709     case Cos:
 710     case Sin:
 711     case Tan:
 712     case Acos:
 713     case Asin:
 714     case Atan:
 715     case Log:
 716     case Exp:
 717     case Abs:
 718     case Ceil:
 719     case Floor:
 720     case Recall:
 721     case Inc:
 722     case Dec:
 723     case Not:
 724     case Cond:
 725         if (root->ops[0]) {
 726             op0 = evaluate_element (root->ops[0], 0);
 727         } else {
 728             VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[0])\n"));
 729             return 0;
 730         }
 731         break;
 732     case Disp:
 733     case Quit:
 734     case Help:
 735     case Ans:
 736     case Pi:
 737     case E:
 738     case Prog:
 739         break;
 740     case While:
 741         if (root->ops[0] == NULL) {
 742             VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[0])\n"));
 743             return 0;
 744         }
 745         break;
 746     }
 747
 748     switch (root->func) {
 749     case Val: return op0;
 750     case Sig: return -op0;
 751     case Add: return ((mask & MASK_SUB) == 0) ? op0 + op1 : op0 - op1;
 752     case Sub: return ((mask & MASK_SUB) == 0) ? op0 - op1 : op0 + op1;
 753     case Mul: return ((mask & MASK_DIV) == 0) ? op0 * op1 : op0 / op1;
 754     case Div: return ((mask & MASK_DIV) == 0) ? op0 / op1 : op0 * op1;
 755     case Mod: return fmod (op0, op1);
 756     case Pow: return pow (op0, op1);
 757     case Sqr: return sqrt (op0);
 758     case Cos: return cos (op0);
 759     case Sin: return sin (op0);
 760     case Tan: return tan (op0);
 761     case Acos: return acos (op0);
 762     case Asin: return asin (op0);
 763     case Atan: return atan (op0);
 764     case Log: return log (op0);
 765     case Exp: return exp (op0);
 766     case Abs: return fabs (op0);
 767     case Ceil: return ceil (op0);
 768     case Floor: return floor (op0);
 769     case Store: return store ((int)op0, (op1) ? op1 : answer);
 770     case Recall: return recall ((int)op0);
 771     case Inc: return increase ((int)op0);
 772     case Dec: return decrease ((int)op0);
 773     case Disp: display (); break;
 774     case Quit: quit (); break;
 775     case Help: help (); break;
 776     case Ans: return answer;
 777     case Pi: return M_PI;
 778     case E: return M_E;
 779     case Equal: return op0 == op1;
 780     case Diff: return op0 != op1;
 781     case Ge: return op0 >= op1;
 782     case Le: return op0 <= op1;
 783     case Gt: return op0 > op1;
 784     case Lt: return op0 < op1;
 785     case And: return (op0 != 0) && (op1 != 0);
 786     case Or: return (op0 != 0) || (op1 != 0);
 787     case Not: return (op0 == 0);
 788     case Cond:
 789         if ((op0) && (root->ops[1])) {
 790             return evaluate_element (root->ops[1], 0);
 791         } else if ((!op0) && (root->ops[2])) {
 792             return evaluate_element (root->ops[2], 0);
 793         } else {
 794             return 0;
 795         }
 796     case While: return while_do (root->ops[0], root->ops[1]);
 797     case Prog: return program_do (root->ops, root->nbops);
 798     }
 799
 800     return 0;
 801 }
 802
 803 char **generate_completion_list ()
 804 {
 805     int i, l = 0;
 806     char **list = (char **) calloc (NB_FUNCTIONS + NB_CONSTANTS + 1, sizeof (char *));
 807     if (list == NULL) {
 808         VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
 809         exit (1);
 810     }
 811
 812     for (i = 0; i < NB_FUNCTIONS; i++) {
 813         list[l] = strdup ((functions + i)->keyword);
 814         if (list[l] == NULL) {
 815             VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
 816             exit (1);
 817         }
 818         l++;
 819     }
 820
 821     for (i = 0; i < NB_CONSTANTS; i++) {
 822         list[l] = strdup ((constants + i)->keyword);
 823         if (list[l] == NULL) {
 824             VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
 825             exit (1);
 826         }
 827         l++;
 828     }
 829
 830     return (list);
 831 }
 832
 833 void free_completion_list (char **list)
 834 {
 835     int i;
 836
 837     if (list) {
 838         for (i = 0; i < NB_FUNCTIONS + NB_CONSTANTS; i++) {
 839             if (list[i] != NULL) {
 840                 free (list[i]);
 841             }
 842         }
 843         free (list);
 844     }
 845 }
 846
 847
 848 /* vim: set ts=4 sw=4 et: */