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 DEFAULT_STORAGE_SIZE 10
  16 int storage_size = -1;
  17
  18 double *storage = NULL;
  19
  20 #define DEFAULT_FORMAT "=> %.6g\n"
  21 char *format = NULL;
  22 char *minform = NULL;
  23
  24 /* compare codes */
  25
  26 int codecmp (char *ref, char *str)
  27 {
  28     int sig;
  29
  30     while (*ref != '\0') {
  31         if (*ref == '\t') {
  32              sig = (*str == '.') ? -1 : ((*str >= '0') && (*str <= '9'));
  33         } else {
  34             sig = *str - *ref;
  35         }
  36         if (sig != 0) {
  37             return (sig > 0) ? 1 : -1;
  38         }
  39         str++;
  40         ref++;
  41     }
  42
  43     return 0;
  44 }
  45
  46 /* allocate new element */
  47
  48 element_t *newelement (func_t function, int nbops, int prio)
  49 {
  50     element_t *new = (element_t *) calloc (1, sizeof (element_t));
  51     if (new == NULL) {
  52         VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
  53         exit (1);
  54     }
  55     if (nbops) {
  56         new->ops = (element_t **) calloc (nbops, sizeof (element_t *));
  57         if (new->ops == NULL) {
  58             VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
  59             exit (1);
  60         }
  61     }
  62     new->func = function;
  63     new->nbops = nbops;
  64     new->prio = prio;
  65
  66     return new;
  67 }
  68
  69 /* desallocate element */
  70
  71 void delelement (element_t *root)
  72 {
  73     if ((root != NULL) && (root != ERROR_OP)) {
  74         int i;
  75         for (i = 0; i < root->nbops; i++) {
  76             if ((root->ops[i] != NULL) && (root->ops[i] != ERROR_OP)) {
  77                 delelement (root->ops[i]);
  78             }
  79         }
  80         if (root->nbops) {
  81             free (root->ops);
  82         }
  83         free (root);
  84     }
  85 }
  86
  87 /* duplicate element */
  88
  89 element_t *dupelement (element_t *root)
  90 {
  91     element_t *tmp = NULL;
  92     int i;
  93
  94     if ((root == NULL) || (root == ERROR_OP)) {
  95         return root;
  96     }
  97     tmp = newelement (root->func, root->nbops, root->prio);
  98     tmp->value = root->value;
  99     for (i = 0; i < root->nbops; i++) {
 100         tmp->ops[i] = dupelement (root->ops[i]);
 101     }
 102     return tmp;
 103 }
 104
 105 /* functions */
 106
 107 #define NB_OPERATORS 14
 108 keyword_t operators[NB_OPERATORS] = {
 109     { "+\t", Add, 2, 1, 1},
 110     { "-\t", Sub, 2, 1, 1},
 111     { "*",   Mul, 2, 1, 2},
 112     { "/",   Div, 2, 1, 2},
 113     { "%",   Mod, 2, 1, 3},
 114     { "^",   Pow, 2, 1, 4},
 115     { "==",  Equal, 2, 2, -1},
 116     { "!=",  Diff, 2, 2, -1},
 117     { ">=",  Ge, 2, 2, -1},
 118     { "<=",  Le, 2, 2, -1},
 119     { ">",   Gt, 2, 1, -1},
 120     { "<",   Lt, 2, 1, -1},
 121     { "&",   And, 2, 1, -2},
 122     { "|",   Or, 2, 1, -2}
 123 };
 124
 125 #define NB_FUNCTIONS 26
 126 keyword_t functions[NB_FUNCTIONS] = {
 127     { "sqrt", Sqr, 1, 4, 5},
 128     { "pow",  Pow, 2, 3, 5},
 129     { "cos",  Cos, 1, 3, 5},
 130     { "sin",  Sin, 1, 3, 5},
 131     { "tan",  Tan, 1, 3, 5},
 132     { "acos", Acos, 1, 4, 5},
 133     { "asin", Asin, 1, 4, 5},
 134     { "atan", Atan, 1, 4, 5},
 135     { "log",  Log, 1, 3, 5},
 136     { "exp",  Exp, 1, 3, 5},
 137     { "abs",  Abs, 1, 3, 5},
 138     { "floor", Floor, 1, 5, 5},
 139     { "ceil", Ceil, 1, 4, 5},
 140     { "sto",  Store, 2, 3, 5},
 141     { "rcl",  Recall, 1, 3, 5},
 142     { "inc",  Inc, 1, 3, 5},
 143     { "dec",  Dec, 1, 3, 5},
 144     { "disp", Disp, 0, 4, 9},
 145     { "mem",  Mem, 1, 3, 9},
 146     { "clr",  Clear, 0, 3, 9},
 147     { "quit", Quit, 0, 4, 9},
 148     { "help", Help, 0, 4, 9},
 149     { "!",    Not, 1, 1, 6},
 150     { "cond", Cond, 3, 4, 5},
 151     { "while", While, 2, 5, 5},
 152     { "print", Print, 1, 5, 5}
 153 };
 154
 155 #define NB_CONSTANTS 3
 156 keyword_t constants[NB_CONSTANTS] = {
 157     { "ans", Ans, 0, 3, 5},
 158     { "e",   E, 0, 1, 5},
 159     { "pi",  Pi, 0, 2, 5}
 160 };
 161
 162 #define NB_SYMBOLS 4
 163 char *symbols[NB_SYMBOLS] = {
 164     "(", ")", "{", "}"
 165 };
 166
 167 /* subparser function */
 168
 169 element_t *subparser (element_t **proot, char **pstr, func_t func, int nbops, int prio)
 170 {
 171     element_t *new = newelement (func, nbops, prio);
 172     new->ops[0] = *proot;
 173     new->ops[1] = parser (*pstr, pstr, new->prio);
 174     if ((new->ops[1] == NULL) || ((new->ops[1] != ERROR_OP) && (new->ops[1]->prio == 9))) {
 175         delelement (new->ops[1]);
 176         new->ops[1] = ERROR_OP;
 177     }
 178     if (new->ops[1] == ERROR_OP) {
 179         delelement (new);
 180         *proot = NULL;
 181         return ERROR_OP;
 182     }
 183     *proot = newelement (Val, 1, 5);
 184     (*proot)->ops[0] = new;
 185
 186     return *proot;
 187 }
 188
 189 /* parser function */
 190
 191 element_t *parser (char *str, char **next, int prio)
 192 {
 193     element_t *root = NULL;
 194     int i;
 195
 196     VERBOSE (DEBUG, fprintf (stdout, "Starting parsing\n"));
 197
 198     /* main loop */
 199     while (*str != '\0') {
 200         int found = 0;
 201         element_t *new = NULL;
 202         VERBOSE (INFO, fprintf (stdout, "Processing: %s\n", str));
 203
 204         /* end without printing */
 205
 206         if (*str == ';') {
 207             if (root) {
 208                 root->hidden = 1;
 209             }
 210             break;
 211         }
 212
 213         /* skip spaces and tabs */
 214
 215         if ((*str == ' ') || (*str == '\t')) {
 216             str++;
 217             continue;
 218         }
 219
 220         /* check for open brace */
 221
 222         if (*str == '{') {
 223             VERBOSE (DEBUG, fprintf (stdout, "start processing brace\n"));
 224             if (root != NULL) {
 225                 delelement (root);
 226                 return ERROR_OP;
 227             }
 228             element_t **prog = NULL;
 229             new = newelement (Prog, 0, 5);
 230             root = new;
 231             prog = &root;
 232
 233             do {
 234                 new = parser (str + 1, &str, 0);
 235                 if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
 236                     delelement (new);
 237                     new = ERROR_OP;
 238                 }
 239                 if (new == ERROR_OP) {
 240                     delelement (root);
 241                     return ERROR_OP;
 242                 }
 243                 element_t *newprog = newelement (Prog, (*prog)->nbops + 1, 5);
 244                 for (i = 0; i < (*prog)->nbops; i++) {
 245                     newprog->ops[i] = (*prog)->ops[i];
 246                     (*prog)->ops[i] = NULL;
 247                 }
 248                 newprog->ops[(*prog)->nbops] = new;
 249                 delelement (*prog);
 250                 (*prog) = newprog;
 251             } while (*str == ',');
 252
 253             if (*str != '}') {
 254                 delelement (root);
 255                 return ERROR_OP;
 256             }
 257             str++;
 258             VERBOSE (DEBUG, fprintf (stdout, "stop processing brace\n"));
 259             continue;
 260         }
 261
 262         /* check for open bracket */
 263
 264         if (*str == '(') {
 265             VERBOSE (DEBUG, fprintf (stdout, "start processing bracket\n"));
 266             if (root) {
 267                 do {
 268                     found = 0;
 269                     new = parser (str + 1, &str, 0);
 270                     if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
 271                         delelement (new);
 272                         new = ERROR_OP;
 273                     }
 274                     if ((new == NULL) || (new == ERROR_OP)) {
 275                         delelement (root);
 276                         return ERROR_OP;
 277                     }
 278                     for (i = 0; i < root->nbops; i++) {
 279                         if (root->ops[i] == NULL) {
 280                             root->ops[i] = new;
 281                             found = 1;
 282                             break;
 283                         }
 284                     }
 285                     if (!found) {
 286                         delelement (new);
 287                         delelement (root);
 288                         return ERROR_OP;
 289                     }
 290                 } while (*str == ',');
 291             } else {
 292                 root = newelement (Val, 1, 5);
 293                 new = parser (str + 1, &str, 0);
 294                 if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
 295                     delelement (new);
 296                     new = ERROR_OP;
 297                 }
 298                 if ((new == NULL) || (new == ERROR_OP) || (*str == ',')) {
 299                     delelement (new);
 300                     delelement (root);
 301                     return ERROR_OP;
 302                 }
 303                 root->ops[0] = new;
 304             }
 305             if (*str != ')') {
 306                 delelement (root);
 307                 return ERROR_OP;
 308             }
 309             str++;
 310             VERBOSE (DEBUG, fprintf (stdout, "stop processing bracket\n"));
 311             continue;
 312         }
 313
 314         /* check for closing bracket, closing brace or koma */
 315
 316         if ((*str == ')') || (*str == '}') || (*str == ',')) {
 317             if (prio == -9) {
 318                 delelement (root);
 319                 return ERROR_OP;
 320             }
 321             if (next != NULL) {
 322                 *next = str;
 323             }
 324             return root;
 325         }
 326
 327         /* look for operators */
 328
 329         for (i = 0; i < NB_OPERATORS; i++) {
 330             keyword_t *operator = operators + i;
 331             if (codecmp (operator->keyword, str) == 0) {
 332                 VERBOSE (DEBUG, fprintf (stdout, "start processing operator\n"));
 333                 if (root) {
 334                     if ((prio) && (prio > operator->prio)) {
 335                         VERBOSE (DEBUG, fprintf (stdout, "stop because operator priority\n"));
 336                         *next = str;
 337                         return root;
 338                     }
 339                     str += operator->offset;
 340                     VERBOSE (INFO, fprintf (stdout, "Oper: %d\n", operator->func));
 341                     if (subparser (&root, &str, operator->func, operator->nbops, operator->prio) == ERROR_OP) {
 342                         delelement (root);
 343                         return ERROR_OP;
 344                     }
 345                 } else if (*str == '-') {
 346                     root = newelement (Sig, 1, 9);
 347                 } else {
 348                     return ERROR_OP;
 349                 }
 350                 found = 1;
 351                 VERBOSE (DEBUG, fprintf (stdout, "stop processing operator\n"));
 352                 break;
 353             }
 354         }
 355         if (found) {
 356             continue;
 357         }
 358
 359         /* look for functions */
 360
 361         for (i = 0; i < NB_FUNCTIONS; i++) {
 362             keyword_t *function = functions + i;
 363             if (codecmp (function->keyword, str) == 0) {
 364                 VERBOSE (DEBUG, fprintf (stdout, "start processing function\n"));
 365                 if (root == NULL) {
 366                     VERBOSE (INFO, fprintf (stdout, "Func: %d\n", function->func));
 367                     root = newelement (function->func, function->nbops, function->prio);
 368                 } else {
 369                     delelement (root);
 370                     return ERROR_OP;
 371                 }
 372                 str += function->offset;
 373                 found = 1;
 374                 VERBOSE (DEBUG, fprintf (stdout, "stop processing function\n"));
 375                 break;
 376             }
 377         }
 378         if (found) {
 379             continue;
 380         }
 381
 382         /* look for constant */
 383
 384         for (i = 0; i < NB_CONSTANTS; i++) {
 385             keyword_t *constant = constants + i;
 386             if (codecmp (constant->keyword, str) == 0) {
 387                 VERBOSE (DEBUG, fprintf (stdout, "start processing constant\n"));
 388                 if (root == NULL) {
 389                     VERBOSE (INFO, fprintf (stdout, "Const: %d\n", constant->func));
 390                     root = newelement (constant->func, constant->nbops, constant->prio);
 391                 } else {
 392                     delelement (root);
 393                     return ERROR_OP;
 394                 }
 395                 str += constant->offset;
 396                 found = 1;
 397                 VERBOSE (DEBUG, fprintf (stdout, "stop processing constant\n"));
 398                 break;
 399             }
 400         }
 401         if (found) {
 402             continue;
 403         }
 404
 405         /* look for number */
 406
 407         if (((*str >= '0') && (*str <= '9')) ||
 408             (*str == '.') || (*str == '+') || (*str == '-')) {
 409             VERBOSE (DEBUG, fprintf (stdout, "start processing value\n"));
 410             char *pt;
 411             double value = strtod (str, &pt);
 412             VERBOSE (INFO, fprintf (stdout, "Value: %f\n", value));
 413             if (str != pt) {
 414                 if ((root == NULL) || (root->prio == 6)) {
 415                     new = newelement (Val, 1, 5);
 416                     new->value = value;
 417                     if (root == NULL) {
 418                         root = new;
 419                     } else {
 420                         for (i = 0; i < root->nbops; i++) {
 421                             if (root->ops[i] == NULL) {
 422                                 root->ops[i] = new;
 423                                 found = 1;
 424                                 break;
 425                             }
 426                         }
 427                         if (!found) {
 428                             delelement (new);
 429                             delelement (root);
 430                             return ERROR_OP;
 431                         }
 432                     }
 433                     str = pt;
 434                 } else if ((*str == '+') || (*str == '-')) {
 435                     if ((prio) && (prio > 1)) {
 436                         VERBOSE (DEBUG, fprintf (stdout, "stop because operator priority\n"));
 437                         *next = str;
 438                         return root;
 439                     }
 440                     if (subparser (&root, &str, Add, 2, 1) == ERROR_OP) {
 441                         delelement (root);
 442                         return ERROR_OP;
 443                     }
 444                 } else {
 445                     delelement (root);
 446                     return ERROR_OP;
 447                 }
 448                 found = 1;
 449             }
 450             VERBOSE (DEBUG, fprintf (stdout, "stop processing value\n"));
 451         }
 452
 453         /* error */
 454
 455         if (!found) {
 456             delelement (root);
 457             return ERROR_OP;
 458         }
 459
 460     }
 461
 462     if (next != NULL) {
 463         *next = str;
 464     }
 465
 466     return root;
 467 }
 468
 469 /* print element tree */
 470
 471 void print_element (element_t *root, int level)
 472 {
 473     char *func = NULL;
 474     int i;
 475
 476     if ((root == NULL) || (root == ERROR_OP)) {
 477         return;
 478     }
 479
 480     for (i = 0; i < level; i++) {
 481         fprintf (stdout, " ");
 482     }
 483
 484     switch (root->func) {
 485     case Val: func = "Value"; break;
 486     case Sig: func = "Sign"; break;
 487     case Add: func = "Addition"; break;
 488     case Sub: func = "Subtraction"; break;
 489     case Mul: func = "Multiplication"; break;
 490     case Div: func = "Division"; break;
 491     case Mod: func = "Modulo"; break;
 492     case Pow: func = "Power"; break;
 493     case Sqr: func = "Square Root"; break;
 494     case Cos: func = "Cosine"; break;
 495     case Sin: func = "Sine"; break;
 496     case Tan: func = "Tangent"; break;
 497     case Acos: func = "Arc Cosine"; break;
 498     case Asin: func = "Arc Sine"; break;
 499     case Atan: func = "Arc Tangent"; break;
 500     case Log: func = "Logarithm"; break;
 501     case Exp: func = "Exponantial"; break;
 502     case Abs: func = "Absolute value"; break;
 503     case Ceil: func = "Ceil value"; break;
 504     case Floor: func = "Floor value"; break;
 505     case Store: func = "Store"; break;
 506     case Recall: func = "Recall"; break;
 507     case Inc: func = "Increase"; break;
 508     case Dec: func = "Decrease"; break;
 509     case Disp: func = "Display"; break;
 510     case Mem: func = "Memory"; break;
 511     case Clear: func = "Clear"; break;
 512     case Quit: func = "Quit"; break;
 513     case Help: func = "Help"; break;
 514     case Ans: func = "Ans"; break;
 515     case Pi: func = "Pi"; break;
 516     case E: func = "E"; break;
 517     case Equal: func = "Equal"; break;
 518     case Diff: func = "Different"; break;
 519     case Ge: func = "Greater or equal"; break;
 520     case Le: func = "Lesser or equal"; break;
 521     case Gt: func = "Greater"; break;
 522     case Lt: func = "Lesser"; break;
 523     case And: func = "And"; break;
 524     case Or: func = "Or"; break;
 525     case Not: func = "Not"; break;
 526     case Cond: func = "Condition"; break;
 527     case While: func = "While"; break;
 528     case Prog: func = "Program"; break;
 529     case Print: func = "Print"; break;
 530     }
 531
 532     fprintf (stdout, "Function: %s\n", func);
 533
 534     if ((root->func == Val) && (root->ops[0] == NULL)) {
 535         for (i = 0; i < level; i++) {
 536             fprintf (stdout, " ");
 537         }
 538         fprintf (stdout, "value: %f\n", root->value);
 539     } else {
 540         for (i = 0; i < root->nbops; i++) {
 541             print_element (root->ops[i], level + 1);
 542         }
 543     }
 544 }
 545
 546 /* storage functions */
 547
 548 void memory (int nb)
 549 {
 550     int i, l;
 551     double *tmp = NULL;
 552     if (nb != storage_size) {
 553         l = (nb < storage_size) ? nb : storage_size;
 554         tmp = (double *) calloc (nb, sizeof (double));
 555         if (tmp == NULL) {
 556             VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
 557             exit (1);
 558         }
 559         for (i = 0; i < l; i++) {
 560             tmp[i] = storage[i];
 561         }
 562         if (storage != NULL) {
 563             free (storage);
 564         }
 565         storage = tmp;
 566         storage_size = nb;
 567     }
 568 }
 569
 570 double store (int index, double value)
 571 {
 572     if (storage_size == -1) {
 573         memory (DEFAULT_STORAGE_SIZE);
 574     }
 575     if ((index > 0) && (index <= storage_size)) {
 576         storage[index - 1] = value;
 577     } else {
 578         VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [%d, %d]\n", index, (storage_size) ? 1 : 0, storage_size));
 579     }
 580     return value;
 581 }
 582
 583 double recall (int index)
 584 {
 585     if (storage_size == -1) {
 586         memory (DEFAULT_STORAGE_SIZE);
 587     }
 588     if ((index > 0) && (index <= storage_size)) {
 589         return storage[index - 1];
 590     } else {
 591         VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [%d, %d]\n", index, (storage_size) ? 1 : 0, storage_size));
 592     }
 593     return 0;
 594 }
 595
 596 double increase (int index)
 597 {
 598     if (storage_size == -1) {
 599         memory (DEFAULT_STORAGE_SIZE);
 600     }
 601     if ((index > 0) && (index <= storage_size)) {
 602         return storage[index - 1]++;
 603     } else {
 604         VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [%d, %d]\n", index, (storage_size) ? 1 : 0, storage_size));
 605     }
 606     return 0;
 607 }
 608
 609 double decrease (int index)
 610 {
 611     if (storage_size == -1) {
 612         memory (DEFAULT_STORAGE_SIZE);
 613     }
 614     if ((index > 0) && (index <= storage_size)) {
 615         return storage[index - 1]--;
 616     } else {
 617         VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [%d, %d]\n", index, (storage_size) ? 1 : 0, storage_size));
 618     }
 619     return 0;
 620 }
 621
 622 void display (void)
 623 {
 624     int i;
 625     if (storage_size == -1) {
 626         memory (DEFAULT_STORAGE_SIZE);
 627     }
 628     fprintf (stdout, "storage:");
 629     for (i = 0; i < storage_size; i++) {
 630         fprintf (stdout, " ");
 631         fprintf (stdout, minform, storage[i]);
 632     }
 633     fprintf (stdout, "\n");
 634 }
 635
 636 void clear ()
 637 {
 638     int i;
 639     for (i = 0; i < storage_size; i++) {
 640         storage[i] = 0;
 641     }
 642 }
 643
 644 /* While do function */
 645
 646 double while_do (element_t *cond, element_t *action)
 647 {
 648     double ret = 0;
 649     element_t *temp = NULL;
 650
 651     VERBOSE (DEBUG, fprintf (stdout, "starting while loop\n"));
 652     while (1) {
 653         VERBOSE (DEBUG, fprintf (stdout, "loop...\n"));
 654
 655         temp = dupelement (cond);
 656         if (!evaluate_element (temp, 0)) {
 657             break;
 658         }
 659         if (action) {
 660             temp = dupelement (action);
 661             ret = evaluate_element (temp, 0);
 662         }
 663     }
 664
 665     VERBOSE (DEBUG, fprintf (stdout, "ending while loop\n"));
 666
 667     return ret;
 668 }
 669
 670 /* program function */
 671
 672 double program_do (element_t **prog, int nbcalls)
 673 {
 674     double ret = 0;
 675     int i;
 676     for (i = 0; i < nbcalls; i++) {
 677         ret = evaluate_element (prog[i], 0);
 678         prog[i] = NULL;
 679     }
 680     return ret;
 681 }
 682
 683 /* print function */
 684
 685 void set_format (char *prompt, int precision)
 686 {
 687     char buffer[128] = {0};
 688     free_format ();
 689     sprintf (buffer, "%s%%.%dg\n", prompt, precision);
 690     format = strdup (buffer);
 691     sprintf (buffer, "%%.%dg", precision);
 692     minform = strdup (buffer);
 693 }
 694
 695 void free_format ()
 696 {
 697     if (format) {
 698         free (format);
 699         format = NULL;
 700     }
 701     if (minform) {
 702         free (minform);
 703         minform = NULL;
 704     }
 705 }
 706
 707 double print (double value)
 708 {
 709     fprintf (stdout, format ? format : DEFAULT_FORMAT, value);
 710     fflush (stdout);
 711     return value;
 712 }
 713
 714 /* quit function */
 715
 716 void quit (void)
 717 {
 718     fprintf (stdout, "bye\n");
 719     exit (0);
 720 }
 721
 722 /* help message */
 723
 724 void help (void)
 725 {
 726     fprintf (stdout, "calc is a simple calculator\n\n");
 727     fprintf (stdout, "supported operators:");
 728     fprintf (stdout, " + - * / %% ^\n");
 729     fprintf (stdout, "camparison operators:");
 730     fprintf (stdout, " == != >= <= > <\n");
 731     fprintf (stdout, "logical operators:");
 732     fprintf (stdout, " & | !\n");
 733     fprintf (stdout, "mathematic functions:");
 734     fprintf (stdout, " pow sqrt log exp\n");
 735     fprintf (stdout, "trig. func.:");
 736     fprintf (stdout, " cos sin tan acos asin atan\n");
 737     fprintf (stdout, "supported functions:");
 738     fprintf (stdout, " abs ceil floor\n");
 739     fprintf (stdout, "storage functions:");
 740     fprintf (stdout, " mem sto rcl inc dec disp\n");
 741     fprintf (stdout, "prog. functions:");
 742     fprintf (stdout, " cond while print {} ;\n");
 743     fprintf (stdout, "misc. functions:");
 744     fprintf (stdout, " quit help\n");
 745     fprintf (stdout, "supported constants:");
 746     fprintf (stdout, " e pi\n");
 747 }
 748
 749 /* evaluate element tree */
 750
 751 #define MASK_SUB 0x1
 752 #define MASK_DIV 0x2
 753
 754 double evaluate_element (element_t *root, char mask)
 755 {
 756     double op0 = 0, op1 = 0;
 757     char nextmask = mask;
 758
 759     if ((root == NULL) || (root == ERROR_OP)) {
 760         VERBOSE (WARNING, fprintf (stdout, "error while evaluating\n"));
 761         return 0;
 762     }
 763
 764     /* mask to manage sub operator sub and div */
 765     switch (root->func) {
 766     case Add:
 767         nextmask &= ~MASK_SUB;
 768         nextmask &= ~MASK_DIV;
 769         break;
 770     case Sub:
 771         nextmask |= MASK_SUB;
 772         nextmask &= ~MASK_DIV;
 773         break;
 774     case Mul:
 775         nextmask &= ~MASK_DIV;
 776         break;
 777     case Div:
 778         nextmask |= MASK_DIV;
 779         break;
 780     default:
 781         nextmask = mask;
 782     }
 783
 784     switch (root->func) {
 785     case Val:
 786     case Sig:
 787         op0 = (root->ops[0]) ? evaluate_element (root->ops[0], nextmask) : root->value;
 788         break;
 789     case Add:
 790     case Sub:
 791     case Mul:
 792     case Div:
 793     case Mod:
 794     case Pow:
 795     case Store:
 796     case Equal:
 797     case Diff:
 798     case Ge:
 799     case Le:
 800     case Gt:
 801     case Lt:
 802     case And:
 803     case Or:
 804         if (root->ops[1]) {
 805             op1 = evaluate_element (root->ops[1], nextmask);
 806         } else if (root->func != Store) {
 807             VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[1])\n"));
 808             return 0;
 809         }
 810         /* fallthrough */
 811     case Sqr:
 812     case Cos:
 813     case Sin:
 814     case Tan:
 815     case Acos:
 816     case Asin:
 817     case Atan:
 818     case Log:
 819     case Exp:
 820     case Abs:
 821     case Ceil:
 822     case Floor:
 823     case Recall:
 824     case Inc:
 825     case Dec:
 826     case Not:
 827     case Mem:
 828     case Cond:
 829         if (root->ops[0]) {
 830             op0 = evaluate_element (root->ops[0], 0);
 831         } else {
 832             VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[0])\n"));
 833             return 0;
 834         }
 835         break;
 836     case Disp:
 837     case Clear:
 838     case Quit:
 839     case Help:
 840     case Ans:
 841     case Pi:
 842     case E:
 843     case Prog:
 844         break;
 845     case While:
 846         if (root->ops[0] == NULL) {
 847             VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[0])\n"));
 848             return 0;
 849         }
 850         break;
 851     case Print:
 852         op0 = (root->ops[0]) ? evaluate_element (root->ops[0], 0) : answer;
 853         break;
 854     }
 855
 856     switch (root->func) {
 857     case Val: return op0;
 858     case Sig: return -op0;
 859     case Add: return ((mask & MASK_SUB) == 0) ? op0 + op1 : op0 - op1;
 860     case Sub: return ((mask & MASK_SUB) == 0) ? op0 - op1 : op0 + op1;
 861     case Mul: return ((mask & MASK_DIV) == 0) ? op0 * op1 : op0 / op1;
 862     case Div: return ((mask & MASK_DIV) == 0) ? op0 / op1 : op0 * op1;
 863     case Mod: return fmod (op0, op1);
 864     case Pow: return pow (op0, op1);
 865     case Sqr: return sqrt (op0);
 866     case Cos: return cos (op0);
 867     case Sin: return sin (op0);
 868     case Tan: return tan (op0);
 869     case Acos: return acos (op0);
 870     case Asin: return asin (op0);
 871     case Atan: return atan (op0);
 872     case Log: return log (op0);
 873     case Exp: return exp (op0);
 874     case Abs: return fabs (op0);
 875     case Ceil: return ceil (op0);
 876     case Floor: return floor (op0);
 877     case Store: return store ((int)op0, (op1) ? op1 : answer);
 878     case Recall: return recall ((int)op0);
 879     case Inc: return increase ((int)op0);
 880     case Dec: return decrease ((int)op0);
 881     case Disp: display (); break;
 882     case Mem: memory ((int)op0); break;
 883     case Clear: clear (); break;
 884     case Quit: quit (); break;
 885     case Help: help (); break;
 886     case Ans: return answer;
 887     case Pi: return M_PI;
 888     case E: return M_E;
 889     case Equal: return op0 == op1;
 890     case Diff: return op0 != op1;
 891     case Ge: return op0 >= op1;
 892     case Le: return op0 <= op1;
 893     case Gt: return op0 > op1;
 894     case Lt: return op0 < op1;
 895     case And: return (op0 != 0) && (op1 != 0);
 896     case Or: return (op0 != 0) || (op1 != 0);
 897     case Not: return (op0 == 0);
 898     case Cond:
 899         if ((op0) && (root->ops[1])) {
 900             return evaluate_element (root->ops[1], 0);
 901         } else if ((!op0) && (root->ops[2])) {
 902             return evaluate_element (root->ops[2], 0);
 903         } else {
 904             return 0;
 905         }
 906     case While: return while_do (root->ops[0], root->ops[1]);
 907     case Prog: return program_do (root->ops, root->nbops);
 908     case Print: return print (op0);
 909     }
 910
 911     return 0;
 912 }
 913
 914 char **generate_completion_list ()
 915 {
 916     int i, j, l = 0;
 917     char **list = (char **) calloc (NB_OPERATORS + NB_FUNCTIONS + NB_CONSTANTS + NB_SYMBOLS + 1, sizeof (char *));
 918     if (list == NULL) {
 919         VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
 920         exit (1);
 921     }
 922
 923     for (i = 0; i < NB_OPERATORS; i++) {
 924         list[l] = strdup ((operators + i)->keyword);
 925         for (j = 0; j < (int)strlen (list[l]); j++) {
 926             if (list[i][j] == '\t') {
 927                 list[i][j] = '\0';
 928             }
 929         }
 930         if (list[l] != NULL) {
 931             l++;
 932         }
 933     }
 934
 935     for (i = 0; i < NB_FUNCTIONS; i++) {
 936         list[l] = strdup ((functions + i)->keyword);
 937         if (list[l] != NULL) {
 938             l++;
 939         }
 940     }
 941
 942     for (i = 0; i < NB_CONSTANTS; i++) {
 943         list[l] = strdup ((constants + i)->keyword);
 944         if (list[l] != NULL) {
 945             l++;
 946         }
 947     }
 948
 949     for (i = 0; i < NB_SYMBOLS; i++) {
 950         list[l] = strdup (symbols[i]);
 951         if (list[l] != NULL) {
 952             l++;
 953         }
 954     }
 955
 956     return (list);
 957 }
 958
 959 void free_completion_list (char **list)
 960 {
 961     int i;
 962
 963     if (list) {
 964         for (i = 0; i < NB_FUNCTIONS + NB_CONSTANTS; i++) {
 965             if (list[i] != NULL) {
 966                 free (list[i]);
 967             }
 968         }
 969         free (list);
 970     }
 971 }
 972
 973
 974 /* vim: set ts=4 sw=4 et: */