parser.c

   1 #include <math.h>
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5
   6 #include "alloc.h"
   7 #include "debug.h"
   8 #include "element.h"
   9 #include "format.h"
  10 #include "program.h"
  11 #include "stack.h"
  12 #include "storage.h"
  13
  14 #include "parser.h"
  15
  16 /* global variables */
  17
  18 double answer = 0;
  19
  20 /* compare codes */
  21
  22 int codecmp (char *ref, char *str)
  23 {
  24     int sig;
  25
  26     while (*ref != '\0') {
  27         if (*ref == '\t') {
  28              sig = (*str == '.') ? -1 : ((*str >= '0') && (*str <= '9'));
  29         } else {
  30             sig = *str - *ref;
  31         }
  32         if (sig != 0) {
  33             return (sig > 0) ? 1 : -1;
  34         }
  35         str++;
  36         ref++;
  37     }
  38
  39     return 0;
  40 }
  41
  42 /* functions */
  43
  44 #define MAX_ARGS 100
  45
  46 #define NB_OPERATORS 14
  47 keyword_t operators[NB_OPERATORS] = {
  48     { "+\t", Add, 2, 1, 1},
  49     { "-\t", Sub, 2, 1, 1},
  50     { "*",   Mul, 2, 1, 2},
  51     { "/",   Div, 2, 1, 2},
  52     { "%",   Mod, 2, 1, 3},
  53     { "^",   Pow, 2, 1, 4},
  54     { "==",  Equal, 2, 2, -1},
  55     { "!=",  Diff, 2, 2, -1},
  56     { ">=",  Ge, 2, 2, -1},
  57     { "<=",  Le, 2, 2, -1},
  58     { ">",   Gt, 2, 1, -1},
  59     { "<",   Lt, 2, 1, -1},
  60     { "&",   And, 2, 1, -2},
  61     { "|",   Or, 2, 1, -2}
  62 };
  63
  64 #define NB_FUNCTIONS 50
  65 keyword_t functions[NB_FUNCTIONS] = {
  66     { "sqrt", Sqr, 1, 4, 5},
  67     { "pow",  Pow, 2, 3, 5},
  68     { "cos",  Cos, 1, 3, 5},
  69     { "sin",  Sin, 1, 3, 5},
  70     { "tan",  Tan, 1, 3, 5},
  71     { "acos", Acos, 1, 4, 5},
  72     { "asin", Asin, 1, 4, 5},
  73     { "atan", Atan, 1, 4, 5},
  74     { "ln",   Ln, 1, 2, 5},
  75     { "log",  Log, 1, 3, 5},
  76     { "exp",  Exp, 1, 3, 5},
  77     { "erfc", Erfc, 1, 4, 5},
  78     { "erf",  Erf, 1, 3, 5},
  79     { "abs",  Abs, 1, 3, 5},
  80     { "floor", Floor, 1, 5, 5},
  81     { "ceil", Ceil, 1, 4, 5},
  82     { "sto",  Store, 2, 3, 5},
  83     { "rcl",  Recall, 1, 3, 5},
  84     { "inc",  Inc, 1, 3, 5},
  85     { "dec",  Dec, 1, 3, 5},
  86     { "disp", Disp, 0, 4, 9},
  87     { "mem",  Mem, 1, 3, 5},
  88     { "clr",  Clear, 0, 3, 9},
  89     { "quit", Quit, 0, 4, 9},
  90     { "help", Help, 0, 4, 9},
  91     { "!",    Not, 1, 1, 6},
  92     { "cond", Cond, 3, 4, 5},
  93     { "while", While, 2, 5, 5},
  94     { "print", Print, 1, 5, 5},
  95     { "prog", Prog, 2, 4, 9},
  96     { "arg",  Arg, 1, 3, 5},
  97     { "call", Call, MAX_ARGS, 4, 5},
  98     { "ls",   List, 0, 2, 9},
  99     { "edit", Edit, 1, 4, 9},
 100     { "del",  Del, 1, 3, 9},
 101     { "get",  Get, 1, 3, 5},
 102     { "len",  Length, 0, 3, 5},
 103     { "pop",  Pop, 0, 3, 5},
 104     { "push", Push, 1, 4, 5},
 105     { "put",  Put, 2, 3, 5},
 106     { "set",  Set, MAX_ARGS, 3, 5},
 107     { "show", Show, 0, 4, 5},
 108     { "max",  Max, 2, 3, 5},
 109     { "mean", Mean, 2, 4, 5},
 110     { "med",  Median, 0, 3, 5},
 111     { "min",  Min, 2, 3, 5},
 112     { "ord",  Order, 0, 3, 5},
 113     { "prod", Prod, 0, 4, 5},
 114     { "sum",  Sum, 0, 3, 5},
 115     { "var",  Variance, 2, 3, 5},
 116 };
 117
 118 #define NB_CONSTANTS 3
 119 keyword_t constants[NB_CONSTANTS] = {
 120     { "ans", Ans, 0, 3, 5},
 121     { "e",   E, 0, 1, 5},
 122     { "pi",  Pi, 0, 2, 5}
 123 };
 124
 125 #define NB_SYMBOLS 4
 126 char *symbols[NB_SYMBOLS] = {
 127     "(", ")", "{", "}"
 128 };
 129
 130 /* subparser function */
 131
 132 element_t *subparser (element_t **proot, char **pstr, func_t func, int nbops, int prio)
 133 {
 134     element_t *new = newelement (func, nbops, prio);
 135     new->ops[0] = *proot;
 136     new->ops[1] = parser (*pstr, pstr, new->prio);
 137     if ((new->ops[1] == NULL) || ((new->ops[1] != ERROR_OP) && (new->ops[1]->prio == 9))) {
 138         delelement (new->ops[1]);
 139         new->ops[1] = ERROR_OP;
 140     }
 141     if (new->ops[1] == ERROR_OP) {
 142         delelement (new);
 143         *proot = NULL;
 144         return ERROR_OP;
 145     }
 146     *proot = newelement (Val, 1, 5);
 147     (*proot)->ops[0] = new;
 148
 149     return *proot;
 150 }
 151
 152 /* parser function */
 153
 154 element_t *parser (char *str, char **next, int prio)
 155 {
 156     element_t *root = NULL;
 157     char *string = str;
 158     int i;
 159
 160     VERBOSE (DEBUG, fprintf (stdout, "Starting parsing\n"));
 161
 162     /* main loop */
 163     while (*str != '\0') {
 164         int found = 0;
 165         element_t *new = NULL;
 166         VERBOSE (INFO, fprintf (stdout, "Processing: %s\n", str));
 167
 168         /* end without printing */
 169
 170         if (*str == ';') {
 171             if (root) {
 172                 root->hidden = 1;
 173             }
 174             break;
 175         }
 176
 177         /* skip spaces and tabs */
 178
 179         if ((*str == ' ') || (*str == '\t')) {
 180             str++;
 181             continue;
 182         }
 183
 184         /* check for open brace */
 185
 186         if (*str == '{') {
 187             VERBOSE (DEBUG, fprintf (stdout, "start processing brace\n"));
 188             if (root != NULL) {
 189                 delelement (root);
 190                 return ERROR_OP;
 191             }
 192             root = newelement (Code, 0, 5);
 193
 194             do {
 195                 new = parser (str + 1, &str, 0);
 196                 if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
 197                     delelement (new);
 198                     new = ERROR_OP;
 199                 }
 200                 if (new == ERROR_OP) {
 201                     delelement (root);
 202                     return ERROR_OP;
 203                 }
 204                 element_t *newcode = newelement (Code, root->nbops + 1, 5);
 205                 for (i = 0; i < root->nbops; i++) {
 206                     newcode->ops[i] = root->ops[i];
 207                     root->ops[i] = NULL;
 208                 }
 209                 newcode->ops[root->nbops] = new;
 210                 delelement (root);
 211                 root = newcode;
 212             } while (*str == ',');
 213
 214             if (*str != '}') {
 215                 delelement (root);
 216                 return ERROR_OP;
 217             }
 218             str++;
 219             VERBOSE (DEBUG, fprintf (stdout, "stop processing brace\n"));
 220             continue;
 221         }
 222
 223         /* check for open bracket */
 224
 225         if (*str == '(') {
 226             VERBOSE (DEBUG, fprintf (stdout, "start processing bracket\n"));
 227             if (root) {
 228                 do {
 229                     found = 0;
 230                     new = parser (str + 1, &str, 0);
 231                     if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
 232                         delelement (new);
 233                         new = ERROR_OP;
 234                     }
 235                     if ((new == NULL) || (new == ERROR_OP)) {
 236                         delelement (root);
 237                         return ERROR_OP;
 238                     }
 239                     for (i = 0; i < root->nbops; i++) {
 240                         if (root->ops[i] == NULL) {
 241                             root->ops[i] = new;
 242                             found = 1;
 243                             break;
 244                         }
 245                     }
 246                     if (!found) {
 247                         delelement (new);
 248                         delelement (root);
 249                         return ERROR_OP;
 250                     }
 251                 } while (*str == ',');
 252             } else {
 253                 root = newelement (Val, 1, 5);
 254                 new = parser (str + 1, &str, 0);
 255                 if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
 256                     delelement (new);
 257                     new = ERROR_OP;
 258                 }
 259                 if ((new == NULL) || (new == ERROR_OP) || (*str == ',')) {
 260                     delelement (new);
 261                     delelement (root);
 262                     return ERROR_OP;
 263                 }
 264                 root->ops[0] = new;
 265             }
 266             if (*str != ')') {
 267                 delelement (root);
 268                 return ERROR_OP;
 269             }
 270             str++;
 271             VERBOSE (DEBUG, fprintf (stdout, "stop processing bracket\n"));
 272             continue;
 273         }
 274
 275         /* check for closing bracket, closing brace or koma */
 276
 277         if ((*str == ')') || (*str == '}') || (*str == ',')) {
 278             if (prio == -9) {
 279                 delelement (root);
 280                 return ERROR_OP;
 281             }
 282             if (next != NULL) {
 283                 *next = str;
 284             }
 285             return root;
 286         }
 287
 288         /* look for operators */
 289
 290         for (i = 0; i < NB_OPERATORS; i++) {
 291             keyword_t *operator = operators + i;
 292             if (codecmp (operator->keyword, str) == 0) {
 293                 VERBOSE (DEBUG, fprintf (stdout, "start processing operator\n"));
 294                 if ((root) && (root->prio == 9)) {
 295                     VERBOSE (DEBUG, fprintf (stdout, "terminal function (%d)\n", root->func));
 296                     delelement (root);
 297                     return ERROR_OP;
 298                 } else if (root) {
 299                     if ((prio) && (prio > operator->prio)) {
 300                         VERBOSE (DEBUG, fprintf (stdout, "stop because operator priority\n"));
 301                         *next = str;
 302                         return root;
 303                     }
 304                     str += operator->offset;
 305                     VERBOSE (INFO, fprintf (stdout, "Oper: %d\n", operator->func));
 306                     if (subparser (&root, &str, operator->func, operator->nbops, operator->prio) == ERROR_OP) {
 307                         delelement (root);
 308                         return ERROR_OP;
 309                     }
 310                 } else if (*str == '-') {
 311                     root = newelement (Sig, 1, 6);
 312                 } else {
 313                     return ERROR_OP;
 314                 }
 315                 found = 1;
 316                 VERBOSE (DEBUG, fprintf (stdout, "stop processing operator\n"));
 317                 break;
 318             }
 319         }
 320         if (found) {
 321             continue;
 322         }
 323
 324         /* look for functions */
 325
 326         for (i = 0; i < NB_FUNCTIONS; i++) {
 327             keyword_t *function = functions + i;
 328             if (codecmp (function->keyword, str) == 0) {
 329                 VERBOSE (DEBUG, fprintf (stdout, "start processing function\n"));
 330                 if (root == NULL) {
 331                     VERBOSE (INFO, fprintf (stdout, "Func: %d\n", function->func));
 332                     root = newelement (function->func, function->nbops, function->prio);
 333                 } else {
 334                     delelement (root);
 335                     return ERROR_OP;
 336                 }
 337                 str += function->offset;
 338                 found = 1;
 339                 VERBOSE (DEBUG, fprintf (stdout, "stop processing function\n"));
 340                 break;
 341             }
 342         }
 343         if (found) {
 344             continue;
 345         }
 346
 347         /* look for constant */
 348
 349         for (i = 0; i < NB_CONSTANTS; i++) {
 350             keyword_t *constant = constants + i;
 351             if (codecmp (constant->keyword, str) == 0) {
 352                 VERBOSE (DEBUG, fprintf (stdout, "start processing constant\n"));
 353                 if (root == NULL) {
 354                     VERBOSE (INFO, fprintf (stdout, "Const: %d\n", constant->func));
 355                     root = newelement (constant->func, constant->nbops, constant->prio);
 356                 } else {
 357                     delelement (root);
 358                     return ERROR_OP;
 359                 }
 360                 str += constant->offset;
 361                 found = 1;
 362                 VERBOSE (DEBUG, fprintf (stdout, "stop processing constant\n"));
 363                 break;
 364             }
 365         }
 366         if (found) {
 367             continue;
 368         }
 369
 370         /* look for number */
 371
 372         if (((*str >= '0') && (*str <= '9')) ||
 373             (*str == '.') || (*str == '+') || (*str == '-')) {
 374             VERBOSE (DEBUG, fprintf (stdout, "start processing value\n"));
 375             char *pt;
 376             double value = strtod (str, &pt);
 377             VERBOSE (INFO, fprintf (stdout, "Value: %f\n", value));
 378             if (str != pt) {
 379                 if ((root == NULL) || (root->prio == 6)) {
 380                     new = newelement (Val, 1, 5);
 381                     new->value = value;
 382                     if (root == NULL) {
 383                         root = new;
 384                     } else {
 385                         for (i = 0; i < root->nbops; i++) {
 386                             if (root->ops[i] == NULL) {
 387                                 root->ops[i] = new;
 388                                 found = 1;
 389                                 break;
 390                             }
 391                         }
 392                         if (!found) {
 393                             delelement (new);
 394                             delelement (root);
 395                             return ERROR_OP;
 396                         }
 397                     }
 398                     str = pt;
 399                 } else if ((*str == '+') || (*str == '-')) {
 400                     if ((prio) && (prio > 1)) {
 401                         VERBOSE (DEBUG, fprintf (stdout, "stop because operator priority\n"));
 402                         *next = str;
 403                         return root;
 404                     }
 405                     if (subparser (&root, &str, Add, 2, 1) == ERROR_OP) {
 406                         delelement (root);
 407                         return ERROR_OP;
 408                     }
 409                 } else {
 410                     delelement (root);
 411                     return ERROR_OP;
 412                 }
 413                 found = 1;
 414             }
 415             VERBOSE (DEBUG, fprintf (stdout, "stop processing value\n"));
 416         }
 417
 418         /* error */
 419
 420         if (!found) {
 421             delelement (root);
 422             return ERROR_OP;
 423         }
 424
 425     }
 426
 427     if (next != NULL) {
 428         *next = str;
 429     }
 430
 431     /* save string */
 432     if (root != NULL) {
 433         root->string = string;
 434     }
 435
 436     return root;
 437 }
 438
 439 /* print element tree */
 440
 441 void print_element (element_t *root, int level)
 442 {
 443     char *func = NULL;
 444     int i;
 445
 446     if ((root == NULL) || (root == ERROR_OP)) {
 447         return;
 448     }
 449
 450     for (i = 0; i < level; i++) {
 451         fprintf (stdout, " ");
 452     }
 453
 454     switch (root->func) {
 455     case Val: func = "Value"; break;
 456     case Sig: func = "Sign"; break;
 457     case Add: func = "Addition"; break;
 458     case Sub: func = "Subtraction"; break;
 459     case Mul: func = "Multiplication"; break;
 460     case Div: func = "Division"; break;
 461     case Mod: func = "Modulo"; break;
 462     case Pow: func = "Power"; break;
 463     case Sqr: func = "Square Root"; break;
 464     case Cos: func = "Cosine"; break;
 465     case Sin: func = "Sine"; break;
 466     case Tan: func = "Tangent"; break;
 467     case Acos: func = "Arc Cosine"; break;
 468     case Asin: func = "Arc Sine"; break;
 469     case Atan: func = "Arc Tangent"; break;
 470     case Ln: func = "Logarithm (natural)"; break;
 471     case Log: func = "Logarithm (10 base)"; break;
 472     case Exp: func = "Exponantial"; break;
 473     case Erfc: func = "Complementary Error Function"; break;
 474     case Erf: func = "Error Function"; break;
 475     case Abs: func = "Absolute value"; break;
 476     case Ceil: func = "Ceil value"; break;
 477     case Floor: func = "Floor value"; break;
 478     case Store: func = "Store"; break;
 479     case Recall: func = "Recall"; break;
 480     case Inc: func = "Increase"; break;
 481     case Dec: func = "Decrease"; break;
 482     case Disp: func = "Display"; break;
 483     case Mem: func = "Memory"; break;
 484     case Clear: func = "Clear"; break;
 485     case Quit: func = "Quit"; break;
 486     case Help: func = "Help"; break;
 487     case Ans: func = "Ans"; break;
 488     case Pi: func = "Pi"; break;
 489     case E: func = "E"; break;
 490     case Equal: func = "Equal"; break;
 491     case Diff: func = "Different"; break;
 492     case Ge: func = "Greater or equal"; break;
 493     case Le: func = "Lesser or equal"; break;
 494     case Gt: func = "Greater"; break;
 495     case Lt: func = "Lesser"; break;
 496     case And: func = "And"; break;
 497     case Or: func = "Or"; break;
 498     case Not: func = "Not"; break;
 499     case Cond: func = "Condition"; break;
 500     case While: func = "While"; break;
 501     case Code: func = "Code"; break;
 502     case Print: func = "Print"; break;
 503     case Prog: func = "Program"; break;
 504     case Arg: func = "Argument"; break;
 505     case Call: func = "Call"; break;
 506     case List: func = "List"; break;
 507     case Edit: func = "Edit"; break;
 508     case Del: func = "Del"; break;
 509     case Get: func = "Get"; break;
 510     case Length: func = "Length"; break;
 511     case Pop: func = "Pop"; break;
 512     case Push: func = "Push"; break;
 513     case Put: func = "Put"; break;
 514     case Set: func = "Set"; break;
 515     case Show: func = "Show"; break;
 516     case Max: func = "Maximum"; break;
 517     case Mean: func = "Mean"; break;
 518     case Median: func = "Median"; break;
 519     case Min: func = "Minimum"; break;
 520     case Order: func = "Order"; break;
 521     case Prod: func = "Product"; break;
 522     case Sum: func = "Sum"; break;
 523     case Variance: func = "Variance"; break;
 524     }
 525
 526     fprintf (stdout, "Function: %s\n", func);
 527
 528     if ((root->func == Val) && (root->ops[0] == NULL)) {
 529         for (i = 0; i < level; i++) {
 530             fprintf (stdout, " ");
 531         }
 532         fprintf (stdout, "value: %f\n", root->value);
 533     } else {
 534         for (i = 0; i < root->nbops; i++) {
 535             print_element (root->ops[i], level + 1);
 536         }
 537     }
 538 }
 539
 540 /* While do function */
 541
 542 double while_do (element_t *cond, element_t *action)
 543 {
 544     double ret = 0;
 545     element_t *temp = NULL;
 546
 547     VERBOSE (DEBUG, fprintf (stdout, "starting while loop\n"));
 548     while (1) {
 549         VERBOSE (DEBUG, fprintf (stdout, "loop...\n"));
 550
 551         temp = dupelement (cond);
 552         double test = evaluate_element (temp, 0);
 553         delelement (temp);
 554         if (!test) {
 555             break;
 556         }
 557         if (action) {
 558             temp = dupelement (action);
 559             ret = evaluate_element (temp, 0);
 560             delelement (temp);
 561         }
 562     }
 563
 564     VERBOSE (DEBUG, fprintf (stdout, "ending while loop\n"));
 565
 566     return ret;
 567 }
 568
 569 /* program function */
 570
 571 double execute_code (element_t **prog, int nbcalls)
 572 {
 573     double ret = 0;
 574     int i;
 575     for (i = 0; i < nbcalls; i++) {
 576         ret = evaluate_element (prog[i], 0);
 577     }
 578     return ret;
 579 }
 580
 581 /* quit function */
 582
 583 void quit (void)
 584 {
 585     fprintf (stdout, "bye\n");
 586     exit (0);
 587 }
 588
 589 /* help message */
 590
 591 void help (void)
 592 {
 593     fprintf (stdout, "calc is a simple calculator\n\n");
 594     fprintf (stdout, "arithmetic op.:");
 595     fprintf (stdout, " + - * / %% ^\n");
 596     fprintf (stdout, "comparison op.:");
 597     fprintf (stdout, " == != >= <= > <\n");
 598     fprintf (stdout, "logical op.:");
 599     fprintf (stdout, " & | !\n");
 600     fprintf (stdout, "mathematic func.:");
 601     fprintf (stdout, " exp ln log pow sqrt\n");
 602     fprintf (stdout, "trigonometric func.:");
 603     fprintf (stdout, " acos asin atan cos sin tan\n");
 604     fprintf (stdout, "error functions:");
 605     fprintf (stdout, " erf erfc\n");
 606     fprintf (stdout, "miscellaneous func.:");
 607     fprintf (stdout, " abs ceil floor\n");
 608     fprintf (stdout, "storage func.:");
 609     fprintf (stdout, " clear dec disp inc mem rcl sto\n");
 610     fprintf (stdout, "control flow prim.:");
 611     fprintf (stdout, " cond print while {} ;\n");
 612     fprintf (stdout, "program management:");
 613     fprintf (stdout, " arg call del edit ls prog\n");
 614     fprintf (stdout, "stack management:");
 615     fprintf (stdout, " get len pop push put set show\n");
 616     fprintf (stdout, "stack func.:");
 617     fprintf (stdout, " max mean med min ord prod sum var\n");
 618     fprintf (stdout, "control management:");
 619     fprintf (stdout, " help quit\n");
 620     fprintf (stdout, "constants:");
 621     fprintf (stdout, " ans e pi\n");
 622 }
 623
 624 /* evaluate element tree */
 625
 626 #define MASK_SUB 0x1
 627 #define MASK_DIV 0x2
 628
 629 double evaluate_element (element_t *root, char mask)
 630 {
 631     double op0 = 0, op1 = 0;
 632     char nextmask = mask;
 633     int i, nb;
 634
 635     if ((root == NULL) || (root == ERROR_OP)) {
 636         VERBOSE (WARNING, fprintf (stdout, "error while evaluating\n"));
 637         return 0;
 638     }
 639
 640     /* mask to manage sub operator sub and div */
 641     switch (root->func) {
 642     case Add:
 643         nextmask &= ~MASK_SUB;
 644         nextmask &= ~MASK_DIV;
 645         break;
 646     case Sub:
 647         nextmask |= MASK_SUB;
 648         nextmask &= ~MASK_DIV;
 649         break;
 650     case Mul:
 651         nextmask &= ~MASK_DIV;
 652         break;
 653     case Div:
 654         nextmask |= MASK_DIV;
 655         break;
 656     default:
 657         nextmask = mask;
 658     }
 659
 660     switch (root->func) {
 661     case Val:
 662     case Sig:
 663         op0 = (root->ops[0]) ? evaluate_element (root->ops[0], nextmask) : root->value;
 664         break;
 665     case Add:
 666     case Sub:
 667     case Mul:
 668     case Div:
 669     case Mod:
 670     case Pow:
 671     case Store:
 672     case Equal:
 673     case Diff:
 674     case Ge:
 675     case Le:
 676     case Gt:
 677     case Lt:
 678     case And:
 679     case Or:
 680         if (root->ops[1]) {
 681             op1 = evaluate_element (root->ops[1], nextmask);
 682         } else if (root->func != Store) {
 683             VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[1])\n"));
 684             return 0;
 685         }
 686         /* fallthrough */
 687     case Sqr:
 688     case Cos:
 689     case Sin:
 690     case Tan:
 691     case Acos:
 692     case Asin:
 693     case Atan:
 694     case Ln:
 695     case Log:
 696     case Exp:
 697     case Erfc:
 698     case Erf:
 699     case Abs:
 700     case Ceil:
 701     case Floor:
 702     case Recall:
 703     case Inc:
 704     case Dec:
 705     case Not:
 706     case Mem:
 707     case Cond:
 708     case Prog:
 709     case Arg:
 710     case Call:
 711     case Edit:
 712     case Del:
 713     case Get:
 714         if (root->ops[0]) {
 715             op0 = evaluate_element (root->ops[0], 0);
 716         } else {
 717             VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[0])\n"));
 718             return 0;
 719         }
 720         break;
 721     case Disp:
 722     case Clear:
 723     case Quit:
 724     case Help:
 725     case Ans:
 726     case Pi:
 727     case E:
 728     case Code:
 729     case List:
 730     case Length:
 731     case Pop:
 732     case Set:
 733     case Show:
 734     case Median:
 735     case Order:
 736     case Prod:
 737     case Sum:
 738         break;
 739     case While:
 740         if (root->ops[0] == NULL) {
 741             VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[0])\n"));
 742             return 0;
 743         }
 744         break;
 745     case Push:
 746     case Print:
 747         op0 = (root->ops[0]) ? evaluate_element (root->ops[0], 0) : answer;
 748         break;
 749     case Put:
 750         if (root->ops[0]) {
 751             op0 = evaluate_element (root->ops[0], 0);
 752         } else {
 753             VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[0])\n"));
 754             return 0;
 755         }
 756         op1 = (root->ops[1]) ? evaluate_element (root->ops[1], 0) : answer;
 757         break;
 758     case Max:
 759     case Mean:
 760     case Min:
 761     case Variance:
 762         if (root->ops[0]) {
 763             op0 = evaluate_element (root->ops[0], 0);
 764             op1 = (root->ops[1]) ? evaluate_element (root->ops[1], 0) : answer;
 765         }
 766     }
 767
 768     switch (root->func) {
 769     case Val: return op0;
 770     case Sig: return -op0;
 771     case Add: return ((mask & MASK_SUB) == 0) ? op0 + op1 : op0 - op1;
 772     case Sub: return ((mask & MASK_SUB) == 0) ? op0 - op1 : op0 + op1;
 773     case Mul: return ((mask & MASK_DIV) == 0) ? op0 * op1 : op0 / op1;
 774     case Div: return ((mask & MASK_DIV) == 0) ? op0 / op1 : op0 * op1;
 775     case Mod: return fmod (op0, op1);
 776     case Pow: return pow (op0, op1);
 777     case Sqr: return sqrt (op0);
 778     case Cos: return cos (op0);
 779     case Sin: return sin (op0);
 780     case Tan: return tan (op0);
 781     case Acos: return acos (op0);
 782     case Asin: return asin (op0);
 783     case Atan: return atan (op0);
 784     case Ln: return log (op0);
 785     case Log: return log10 (op0);
 786     case Exp: return exp (op0);
 787     case Erfc: return erfc (op0);
 788     case Erf: return erf (op0);
 789     case Abs: return fabs (op0);
 790     case Ceil: return ceil (op0);
 791     case Floor: return floor (op0);
 792     case Store: return store ((int)op0, (op1) ? op1 : answer);
 793     case Recall: return recall ((int)op0);
 794     case Inc: return increase ((int)op0);
 795     case Dec: return decrease ((int)op0);
 796     case Disp: display (); break;
 797     case Mem: memory ((int)op0); break;
 798     case Clear: clear (); break;
 799     case Quit: quit (); break;
 800     case Help: help (); break;
 801     case Ans: return answer;
 802     case Pi: return M_PI;
 803     case E: return M_E;
 804     case Equal: return op0 == op1;
 805     case Diff: return op0 != op1;
 806     case Ge: return op0 >= op1;
 807     case Le: return op0 <= op1;
 808     case Gt: return op0 > op1;
 809     case Lt: return op0 < op1;
 810     case And: return (op0 != 0) && (op1 != 0);
 811     case Or: return (op0 != 0) || (op1 != 0);
 812     case Not: return (op0 == 0);
 813     case Cond:
 814         if ((op0) && (root->ops[1])) {
 815             return evaluate_element (root->ops[1], 0);
 816         } else if ((!op0) && (root->ops[2])) {
 817             return evaluate_element (root->ops[2], 0);
 818         } else {
 819             return 0;
 820         }
 821     case While: return while_do (root->ops[0], root->ops[1]);
 822     case Code: return execute_code (root->ops, root->nbops);
 823     case Print: return print (op0);
 824     case Prog:
 825         prog ((int)op0, root->ops[1]);
 826         savestring ((int)op0, root->string);
 827         break;
 828     case Arg: return arg ((int)op0);
 829     case Call:
 830         for (i = 1, nb =0; i < root->nbops; i++) {
 831             if (root->ops[i]) {
 832                 nb++;
 833             }
 834         }
 835         return call ((int)op0, nb, root->ops + 1);
 836     case List: list (); break;
 837     case Edit: edit ((int)op0); break;
 838     case Del: del ((int)op0); break;
 839     case Get: return get ((int)op0);
 840     case Length: return length ();
 841     case Pop: return pop ();
 842     case Push: return push (op0);
 843     case Put: return put ((int)op0, op1);
 844     case Set:
 845         for (i = 0, nb =0; i < root->nbops; i++) {
 846             if (root->ops[i]) {
 847                 nb++;
 848             }
 849         }
 850         return set (nb, root->ops);
 851     case Show: show (); break;
 852     case Max:
 853         if (root->ops[0]) {
 854             return op0 > op1 ? op0 : op1;
 855         }
 856         return max ();
 857     case Mean:
 858         if (root->ops[0]) {
 859             return (op0 + op1) / 2;
 860         }
 861         return mean ();
 862     case Median: return median ();
 863     case Min:
 864         if (root->ops[0]) {
 865             return op0 < op1 ? op0 : op1;
 866         }
 867         return min ();
 868     case Order: order (); break;
 869     case Prod: return prod ();
 870     case Sum: return sum ();
 871     case Variance:
 872         if (root->ops[0]) {
 873             double m = (op0 + op1) / 2;
 874             op0 -= m;
 875             op1 -= m;
 876             return op0 * op0 + op1 * op1;
 877         }
 878         return variance ();
 879     }
 880
 881     return 0;
 882 }
 883
 884 char **generate_completion_list ()
 885 {
 886     int i, j, l = 0;
 887     char **list = (char **) callocordie (NB_OPERATORS + NB_FUNCTIONS + NB_CONSTANTS + NB_SYMBOLS + 1, sizeof (char *));
 888
 889     for (i = 0; i < NB_OPERATORS; i++) {
 890         list[l] = strdup ((operators + i)->keyword);
 891         for (j = 0; j < (int)strlen (list[l]); j++) {
 892             if (list[i][j] == '\t') {
 893                 list[i][j] = '\0';
 894             }
 895         }
 896         if (list[l] != NULL) {
 897             l++;
 898         }
 899     }
 900
 901     for (i = 0; i < NB_FUNCTIONS; i++) {
 902         list[l] = strdup ((functions + i)->keyword);
 903         if (list[l] != NULL) {
 904             l++;
 905         }
 906     }
 907
 908     for (i = 0; i < NB_CONSTANTS; i++) {
 909         list[l] = strdup ((constants + i)->keyword);
 910         if (list[l] != NULL) {
 911             l++;
 912         }
 913     }
 914
 915     for (i = 0; i < NB_SYMBOLS; i++) {
 916         list[l] = strdup (symbols[i]);
 917         if (list[l] != NULL) {
 918             l++;
 919         }
 920     }
 921
 922     return (list);
 923 }
 924
 925 void free_completion_list (char **list)
 926 {
 927     int i;
 928
 929     if (list) {
 930         for (i = 0; i < NB_OPERATORS + NB_FUNCTIONS + NB_CONSTANTS + NB_SYMBOLS + 1; i++) {
 931             if (list[i] != NULL) {
 932                 free (list[i]);
 933             }
 934         }
 935         free (list);
 936     }
 937 }
 938
 939 /* vim: set ts=4 sw=4 et: */