extend a test

[calc.git] / parser.c

#include <malloc.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "debug.h"

#include "parser.h"

/* global variables */

double answer = 0;

#define DEFAULT_STORAGE_SIZE 10
int storage_size = -1;

double *storage = NULL;

#define DEFAULT_FORMAT "=> %.6g\n"
char *format = NULL;
char *minform = NULL;

/* compare codes */

int codecmp (char *ref, char *str)
{
    int sig;

    while (*ref != '\0') {
        if (*ref == '\t') {
             sig = (*str == '.') ? -1 : ((*str >= '0') && (*str <= '9'));
        } else {
            sig = *str - *ref;
        }
        if (sig != 0) {
            return (sig > 0) ? 1 : -1;
        }
        str++;
        ref++;
    }

    return 0;
}

/* allocate new element */

element_t *newelement (func_t function, int nbops, int prio)
{
    element_t *new = (element_t *) calloc (1, sizeof (element_t));
    if (new == NULL) {
        VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
        exit (1);
    }
    if (nbops) {
        new->ops = (element_t **) calloc (nbops, sizeof (element_t *));
        if (new->ops == NULL) {
            VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
            exit (1);
        }
    }
    new->func = function;
    new->nbops = nbops;
    new->prio = prio;

    return new;
}

/* desallocate element */

void delelement (element_t *root)
{
    if ((root != NULL) && (root != ERROR_OP)) {
        int i;
        for (i = 0; i < root->nbops; i++) {
            if ((root->ops[i] != NULL) && (root->ops[i] != ERROR_OP)) {
                delelement (root->ops[i]);
            }
        }
        if (root->nbops) {
            free (root->ops);
        }
        free (root);
    }
}

/* duplicate element */

element_t *dupelement (element_t *root)
{
    element_t *tmp = NULL;
    int i;

    if ((root == NULL) || (root == ERROR_OP)) {
        return root;
    }
    tmp = newelement (root->func, root->nbops, root->prio);
    tmp->value = root->value;
    for (i = 0; i < root->nbops; i++) {
        tmp->ops[i] = dupelement (root->ops[i]);
    }
    return tmp;
}

/* functions */

#define NB_OPERATORS 14
keyword_t operators[NB_OPERATORS] = {
    { "+\t", Add, 2, 1, 1},
    { "-\t", Sub, 2, 1, 1},
    { "*",   Mul, 2, 1, 2},
    { "/",   Div, 2, 1, 2},
    { "%",   Mod, 2, 1, 3},
    { "^",   Pow, 2, 1, 4},
    { "==",  Equal, 2, 2, -1},
    { "!=",  Diff, 2, 2, -1},
    { ">=",  Ge, 2, 2, -1},
    { "<=",  Le, 2, 2, -1},
    { ">",   Gt, 2, 1, -1},
    { "<",   Lt, 2, 1, -1},
    { "&",   And, 2, 1, -2},
    { "|",   Or, 2, 1, -2}
};

#define NB_FUNCTIONS 26
keyword_t functions[NB_FUNCTIONS] = {
    { "sqrt", Sqr, 1, 4, 5},
    { "pow",  Pow, 2, 3, 5},
    { "cos",  Cos, 1, 3, 5},
    { "sin",  Sin, 1, 3, 5},
    { "tan",  Tan, 1, 3, 5},
    { "acos", Acos, 1, 4, 5},
    { "asin", Asin, 1, 4, 5},
    { "atan", Atan, 1, 4, 5},
    { "log",  Log, 1, 3, 5},
    { "exp",  Exp, 1, 3, 5},
    { "abs",  Abs, 1, 3, 5},
    { "floor", Floor, 1, 5, 5},
    { "ceil", Ceil, 1, 4, 5},
    { "sto",  Store, 2, 3, 5},
    { "rcl",  Recall, 1, 3, 5},
    { "inc",  Inc, 1, 3, 5},
    { "dec",  Dec, 1, 3, 5},
    { "disp", Disp, 0, 4, 9},
    { "mem",  Mem, 1, 3, 9},
    { "clr",  Clear, 0, 3, 9},
    { "quit", Quit, 0, 4, 9},
    { "help", Help, 0, 4, 9},
    { "!",    Not, 1, 1, 6},
    { "cond", Cond, 3, 4, 5},
    { "while", While, 2, 5, 5},
    { "print", Print, 1, 5, 5}
};

#define NB_CONSTANTS 3
keyword_t constants[NB_CONSTANTS] = {
    { "ans", Ans, 0, 3, 5},
    { "e",   E, 0, 1, 5},
    { "pi",  Pi, 0, 2, 5}
};

#define NB_SYMBOLS 4
char *symbols[NB_SYMBOLS] = {
    "(", ")", "{", "}"
};

/* subparser function */

element_t *subparser (element_t **proot, char **pstr, func_t func, int nbops, int prio)
{
    element_t *new = newelement (func, nbops, prio);
    new->ops[0] = *proot;
    new->ops[1] = parser (*pstr, pstr, new->prio);
    if ((new->ops[1] == NULL) || ((new->ops[1] != ERROR_OP) && (new->ops[1]->prio == 9))) {
        delelement (new->ops[1]);
        new->ops[1] = ERROR_OP;
    }
    if (new->ops[1] == ERROR_OP) {
        delelement (new);
        *proot = NULL;
        return ERROR_OP;
    }
    *proot = newelement (Val, 1, 5);
    (*proot)->ops[0] = new;

    return *proot;
}

/* parser function */

element_t *parser (char *str, char **next, int prio)
{
    element_t *root = NULL;
    int i;

    VERBOSE (DEBUG, fprintf (stdout, "Starting parsing\n"));

    /* main loop */
    while (*str != '\0') {
        int found = 0;
        element_t *new = NULL;
        VERBOSE (INFO, fprintf (stdout, "Processing: %s\n", str));

        /* end without printing */

        if (*str == ';') {
            if (root) {
                root->hidden = 1;
            }
            break;
        }

        /* skip spaces and tabs */

        if ((*str == ' ') || (*str == '\t')) {
            str++;
            continue;
        }

        /* check for open brace */

        if (*str == '{') {
            VERBOSE (DEBUG, fprintf (stdout, "start processing brace\n"));
            if (root != NULL) {
                delelement (root);
                return ERROR_OP;
            }
            element_t **prog = NULL;
            new = newelement (Prog, 0, 5);
            root = new;
            prog = &root;

            do {
                new = parser (str + 1, &str, 0);
                if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
                    delelement (new);
                    new = ERROR_OP;
                }
                if (new == ERROR_OP) {
                    delelement (root);
                    return ERROR_OP;
                }
                element_t *newprog = newelement (Prog, (*prog)->nbops + 1, 5);
                for (i = 0; i < (*prog)->nbops; i++) {
                    newprog->ops[i] = (*prog)->ops[i];
                    (*prog)->ops[i] = NULL;
                }
                newprog->ops[(*prog)->nbops] = new;
                delelement (*prog);
                (*prog) = newprog;
            } while (*str == ',');

            if (*str != '}') {
                delelement (root);
                return ERROR_OP;
            }
            str++;
            VERBOSE (DEBUG, fprintf (stdout, "stop processing brace\n"));
            continue;
        }

        /* check for open bracket */

        if (*str == '(') {
            VERBOSE (DEBUG, fprintf (stdout, "start processing bracket\n"));
            if (root) {
                do {
                    found = 0;
                    new = parser (str + 1, &str, 0);
                    if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
                        delelement (new);
                        new = ERROR_OP;
                    }
                    if ((new == NULL) || (new == ERROR_OP)) {
                        delelement (root);
                        return ERROR_OP;
                    }
                    for (i = 0; i < root->nbops; i++) {
                        if (root->ops[i] == NULL) {
                            root->ops[i] = new;
                            found = 1;
                            break;
                        }
                    }
                    if (!found) {
                        delelement (new);
                        delelement (root);
                        return ERROR_OP;
                    }
                } while (*str == ',');
            } else {
                root = newelement (Val, 1, 5);
                new = parser (str + 1, &str, 0);
                if ((new == NULL) || ((new != ERROR_OP) && (new->prio == 9))) {
                    delelement (new);
                    new = ERROR_OP;
                }
                if ((new == NULL) || (new == ERROR_OP) || (*str == ',')) {
                    delelement (new);
                    delelement (root);
                    return ERROR_OP;
                }
                root->ops[0] = new;
            }
            if (*str != ')') {
                delelement (root);
                return ERROR_OP;
            }
            str++;
            VERBOSE (DEBUG, fprintf (stdout, "stop processing bracket\n"));
            continue;
        }

        /* check for closing bracket, closing brace or koma */

        if ((*str == ')') || (*str == '}') || (*str == ',')) {
            if (prio == -9) {
                delelement (root);
                return ERROR_OP;
            }
            if (next != NULL) {
                *next = str;
            }
            return root;
        }

        /* look for operators */

        for (i = 0; i < NB_OPERATORS; i++) {
            keyword_t *operator = operators + i;
            if (codecmp (operator->keyword, str) == 0) {
                VERBOSE (DEBUG, fprintf (stdout, "start processing operator\n"));
                if (root) {
                    if ((prio) && (prio > operator->prio)) {
                        VERBOSE (DEBUG, fprintf (stdout, "stop because operator priority\n"));
                        *next = str;
                        return root;
                    }
                    str += operator->offset;
                    VERBOSE (INFO, fprintf (stdout, "Oper: %d\n", operator->func));
                    if (subparser (&root, &str, operator->func, operator->nbops, operator->prio) == ERROR_OP) {
                        delelement (root);
                        return ERROR_OP;
                    }
                } else if (*str == '-') {
                    root = newelement (Sig, 1, 9);
                } else {
                    return ERROR_OP;
                }
                found = 1;
                VERBOSE (DEBUG, fprintf (stdout, "stop processing operator\n"));
                break;
            }
        }
        if (found) {
            continue;
        }

        /* look for functions */

        for (i = 0; i < NB_FUNCTIONS; i++) {
            keyword_t *function = functions + i;
            if (codecmp (function->keyword, str) == 0) {
                VERBOSE (DEBUG, fprintf (stdout, "start processing function\n"));
                if (root == NULL) {
                    VERBOSE (INFO, fprintf (stdout, "Func: %d\n", function->func));
                    root = newelement (function->func, function->nbops, function->prio);
                } else {
                    delelement (root);
                    return ERROR_OP;
                }
                str += function->offset;
                found = 1;
                VERBOSE (DEBUG, fprintf (stdout, "stop processing function\n"));
                break;
            }
        }
        if (found) {
            continue;
        }

        /* look for constant */

        for (i = 0; i < NB_CONSTANTS; i++) {
            keyword_t *constant = constants + i;
            if (codecmp (constant->keyword, str) == 0) {
                VERBOSE (DEBUG, fprintf (stdout, "start processing constant\n"));
                if (root == NULL) {
                    VERBOSE (INFO, fprintf (stdout, "Const: %d\n", constant->func));
                    root = newelement (constant->func, constant->nbops, constant->prio);
                } else {
                    delelement (root);
                    return ERROR_OP;
                }
                str += constant->offset;
                found = 1;
                VERBOSE (DEBUG, fprintf (stdout, "stop processing constant\n"));
                break;
            }
        }
        if (found) {
            continue;
        }

        /* look for number */

        if (((*str >= '0') && (*str <= '9')) ||
            (*str == '.') || (*str == '+') || (*str == '-')) {
            VERBOSE (DEBUG, fprintf (stdout, "start processing value\n"));
            char *pt;
            double value = strtod (str, &pt);
            VERBOSE (INFO, fprintf (stdout, "Value: %f\n", value));
            if (str != pt) {
                if ((root == NULL) || (root->prio == 6)) {
                    new = newelement (Val, 1, 5);
                    new->value = value;
                    if (root == NULL) {
                        root = new;
                    } else {
                        for (i = 0; i < root->nbops; i++) {
                            if (root->ops[i] == NULL) {
                                root->ops[i] = new;
                                found = 1;
                                break;
                            }
                        }
                        if (!found) {
                            delelement (new);
                            delelement (root);
                            return ERROR_OP;
                        }
                    }
                    str = pt;
                } else if ((*str == '+') || (*str == '-')) {
                    if ((prio) && (prio > 1)) {
                        VERBOSE (DEBUG, fprintf (stdout, "stop because operator priority\n"));
                        *next = str;
                        return root;
                    }
                    if (subparser (&root, &str, Add, 2, 1) == ERROR_OP) {
                        delelement (root);
                        return ERROR_OP;
                    }
                } else {
                    delelement (root);
                    return ERROR_OP;
                }
                found = 1;
            }
            VERBOSE (DEBUG, fprintf (stdout, "stop processing value\n"));
        }

        /* error */

        if (!found) {
            delelement (root);
            return ERROR_OP;
        }

    }

    if (next != NULL) {
        *next = str;
    }

    return root;
}

/* print element tree */

void print_element (element_t *root, int level)
{
    char *func = NULL;
    int i;

    if ((root == NULL) || (root == ERROR_OP)) {
        return;
    }

    for (i = 0; i < level; i++) {
        fprintf (stdout, " ");
    }

    switch (root->func) {
    case Val: func = "Value"; break;
    case Sig: func = "Sign"; break;
    case Add: func = "Addition"; break;
    case Sub: func = "Subtraction"; break;
    case Mul: func = "Multiplication"; break;
    case Div: func = "Division"; break;
    case Mod: func = "Modulo"; break;
    case Pow: func = "Power"; break;
    case Sqr: func = "Square Root"; break;
    case Cos: func = "Cosine"; break;
    case Sin: func = "Sine"; break;
    case Tan: func = "Tangent"; break;
    case Acos: func = "Arc Cosine"; break;
    case Asin: func = "Arc Sine"; break;
    case Atan: func = "Arc Tangent"; break;
    case Log: func = "Logarithm"; break;
    case Exp: func = "Exponantial"; break;
    case Abs: func = "Absolute value"; break;
    case Ceil: func = "Ceil value"; break;
    case Floor: func = "Floor value"; break;
    case Store: func = "Store"; break;
    case Recall: func = "Recall"; break;
    case Inc: func = "Increase"; break;
    case Dec: func = "Decrease"; break;
    case Disp: func = "Display"; break;
    case Mem: func = "Memory"; break;
    case Clear: func = "Clear"; break;
    case Quit: func = "Quit"; break;
    case Help: func = "Help"; break;
    case Ans: func = "Ans"; break;
    case Pi: func = "Pi"; break;
    case E: func = "E"; break;
    case Equal: func = "Equal"; break;
    case Diff: func = "Different"; break;
    case Ge: func = "Greater or equal"; break;
    case Le: func = "Lesser or equal"; break;
    case Gt: func = "Greater"; break;
    case Lt: func = "Lesser"; break;
    case And: func = "And"; break;
    case Or: func = "Or"; break;
    case Not: func = "Not"; break;
    case Cond: func = "Condition"; break;
    case While: func = "While"; break;
    case Prog: func = "Program"; break;
    case Print: func = "Print"; break;
    }

    fprintf (stdout, "Function: %s\n", func);

    if ((root->func == Val) && (root->ops[0] == NULL)) {
        for (i = 0; i < level; i++) {
            fprintf (stdout, " ");
        }
        fprintf (stdout, "value: %f\n", root->value);
    } else {
        for (i = 0; i < root->nbops; i++) {
            print_element (root->ops[i], level + 1);
        }
    }
}

/* storage functions */

void memory (int nb)
{
    int i, l;
    double *tmp = NULL;
    if (nb != storage_size) {
        l = (nb < storage_size) ? nb : storage_size;
        tmp = (double *) calloc (nb, sizeof (double));
        if (tmp == NULL) {
            VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
            exit (1);
        }
        for (i = 0; i < l; i++) {
            tmp[i] = storage[i];
        }
        if (storage != NULL) {
            free (storage);
        }
        storage = tmp;
        storage_size = nb;
    }
}

double store (int index, double value)
{
    if (storage_size == -1) {
        memory (DEFAULT_STORAGE_SIZE);
    }
    if ((index > 0) && (index <= storage_size)) {
        storage[index - 1] = value;
    } else {
        VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [%d, %d]\n", index, (storage_size) ? 1 : 0, storage_size));
    }
    return value;
}

double recall (int index)
{
    if (storage_size == -1) {
        memory (DEFAULT_STORAGE_SIZE);
    }
    if ((index > 0) && (index <= storage_size)) {
        return storage[index - 1];
    } else {
        VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [%d, %d]\n", index, (storage_size) ? 1 : 0, storage_size));
    }
    return 0;
}

double increase (int index)
{
    if (storage_size == -1) {
        memory (DEFAULT_STORAGE_SIZE);
    }
    if ((index > 0) && (index <= storage_size)) {
        return storage[index - 1]++;
    } else {
        VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [%d, %d]\n", index, (storage_size) ? 1 : 0, storage_size));
    }
    return 0;
}

double decrease (int index)
{
    if (storage_size == -1) {
        memory (DEFAULT_STORAGE_SIZE);
    }
    if ((index > 0) && (index <= storage_size)) {
        return storage[index - 1]--;
    } else {
        VERBOSE (WARNING, fprintf (stdout, "invalid index (%d) [%d, %d]\n", index, (storage_size) ? 1 : 0, storage_size));
    }
    return 0;
}

void display (void)
{
    int i;
    if (storage_size == -1) {
        memory (DEFAULT_STORAGE_SIZE);
    }
    fprintf (stdout, "storage:");
    for (i = 0; i < storage_size; i++) {
        fprintf (stdout, " ");
        fprintf (stdout, minform, storage[i]);
    }
    fprintf (stdout, "\n");
}

void clear ()
{
    int i;
    for (i = 0; i < storage_size; i++) {
        storage[i] = 0;
    }
}

/* While do function */

double while_do (element_t *cond, element_t *action)
{
    double ret = 0;
    element_t *temp = NULL;

    VERBOSE (DEBUG, fprintf (stdout, "starting while loop\n"));
    while (1) {
        VERBOSE (DEBUG, fprintf (stdout, "loop...\n"));

        temp = dupelement (cond);
        if (!evaluate_element (temp, 0)) {
            break;
        }
        if (action) {
            temp = dupelement (action);
            ret = evaluate_element (temp, 0);
        }
    }

    VERBOSE (DEBUG, fprintf (stdout, "ending while loop\n"));

    return ret;
}

/* program function */

double program_do (element_t **prog, int nbcalls)
{
    double ret = 0;
    int i;
    for (i = 0; i < nbcalls; i++) {
        ret = evaluate_element (prog[i], 0);
        prog[i] = NULL;
    }
    return ret;
}

/* print function */

void set_format (char *prompt, int precision)
{
    char buffer[128] = {0};
    free_format ();
    sprintf (buffer, "%s%%.%dg\n", prompt, precision);
    format = strdup (buffer);
    sprintf (buffer, "%%.%dg", precision);
    minform = strdup (buffer);
}

void free_format ()
{
    if (format) {
        free (format);
        format = NULL;
    }
    if (minform) {
        free (minform);
        minform = NULL;
    }
}

double print (double value)
{
    fprintf (stdout, format ? format : DEFAULT_FORMAT, value);
    fflush (stdout);
    return value;
}

/* quit function */

void quit (void)
{
    fprintf (stdout, "bye\n");
    exit (0);
}

/* help message */

void help (void)
{
    fprintf (stdout, "calc is a simple calculator\n\n");
    fprintf (stdout, "supported operators:");
    fprintf (stdout, " + - * / %% ^\n");
    fprintf (stdout, "camparison operators:");
    fprintf (stdout, " == != >= <= > <\n");
    fprintf (stdout, "logical operators:");
    fprintf (stdout, " & | !\n");
    fprintf (stdout, "mathematic functions:");
    fprintf (stdout, " pow sqrt log exp\n");
    fprintf (stdout, "trig. func.:");
    fprintf (stdout, " cos sin tan acos asin atan\n");
    fprintf (stdout, "supported functions:");
    fprintf (stdout, " abs ceil floor\n");
    fprintf (stdout, "storage functions:");
    fprintf (stdout, " mem sto rcl inc dec disp\n");
    fprintf (stdout, "prog. functions:");
    fprintf (stdout, " cond while print {} ;\n");
    fprintf (stdout, "misc. functions:");
    fprintf (stdout, " quit help\n");
    fprintf (stdout, "supported constants:");
    fprintf (stdout, " e pi\n");
}

/* evaluate element tree */

#define MASK_SUB 0x1
#define MASK_DIV 0x2

double evaluate_element (element_t *root, char mask)
{
    double op0 = 0, op1 = 0;
    char nextmask = mask;

    if ((root == NULL) || (root == ERROR_OP)) {
        VERBOSE (WARNING, fprintf (stdout, "error while evaluating\n"));
        return 0;
    }

    /* mask to manage sub operator sub and div */
    switch (root->func) {
    case Add:
        nextmask &= ~MASK_SUB;
        nextmask &= ~MASK_DIV;
        break;
    case Sub:
        nextmask |= MASK_SUB;
        nextmask &= ~MASK_DIV;
        break;
    case Mul:
        nextmask &= ~MASK_DIV;
        break;
    case Div:
        nextmask |= MASK_DIV;
        break;
    default:
        nextmask = mask;
    }

    switch (root->func) {
    case Val:
    case Sig:
        op0 = (root->ops[0]) ? evaluate_element (root->ops[0], nextmask) : root->value;
        break;
    case Add:
    case Sub:
    case Mul:
    case Div:
    case Mod:
    case Pow:
    case Store:
    case Equal:
    case Diff:
    case Ge:
    case Le:
    case Gt:
    case Lt:
    case And:
    case Or:
        if (root->ops[1]) {
            op1 = evaluate_element (root->ops[1], nextmask);
        } else if (root->func != Store) {
            VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[1])\n"));
            return 0;
        }
        /* fallthrough */
    case Sqr:
    case Cos:
    case Sin:
    case Tan:
    case Acos:
    case Asin:
    case Atan:
    case Log:
    case Exp:
    case Abs:
    case Ceil:
    case Floor:
    case Recall:
    case Inc:
    case Dec:
    case Not:
    case Mem:
    case Cond:
        if (root->ops[0]) {
            op0 = evaluate_element (root->ops[0], 0);
        } else {
            VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[0])\n"));
            return 0;
        }
        break;
    case Disp:
    case Clear:
    case Quit:
    case Help:
    case Ans:
    case Pi:
    case E:
    case Prog:
        break;
    case While:
        if (root->ops[0] == NULL) {
            VERBOSE (WARNING, fprintf (stdout, "error while evaluating (op[0])\n"));
            return 0;
        }
        break;
    case Print:
        op0 = (root->ops[0]) ? evaluate_element (root->ops[0], 0) : answer;
        break;
    }

    switch (root->func) {
    case Val: return op0;
    case Sig: return -op0;
    case Add: return ((mask & MASK_SUB) == 0) ? op0 + op1 : op0 - op1;
    case Sub: return ((mask & MASK_SUB) == 0) ? op0 - op1 : op0 + op1;
    case Mul: return ((mask & MASK_DIV) == 0) ? op0 * op1 : op0 / op1;
    case Div: return ((mask & MASK_DIV) == 0) ? op0 / op1 : op0 * op1;
    case Mod: return fmod (op0, op1);
    case Pow: return pow (op0, op1);
    case Sqr: return sqrt (op0);
    case Cos: return cos (op0);
    case Sin: return sin (op0);
    case Tan: return tan (op0);
    case Acos: return acos (op0);
    case Asin: return asin (op0);
    case Atan: return atan (op0);
    case Log: return log (op0);
    case Exp: return exp (op0);
    case Abs: return fabs (op0);
    case Ceil: return ceil (op0);
    case Floor: return floor (op0);
    case Store: return store ((int)op0, (op1) ? op1 : answer);
    case Recall: return recall ((int)op0);
    case Inc: return increase ((int)op0);
    case Dec: return decrease ((int)op0);
    case Disp: display (); break;
    case Mem: memory ((int)op0); break;
    case Clear: clear (); break;
    case Quit: quit (); break;
    case Help: help (); break;
    case Ans: return answer;
    case Pi: return M_PI;
    case E: return M_E;
    case Equal: return op0 == op1;
    case Diff: return op0 != op1;
    case Ge: return op0 >= op1;
    case Le: return op0 <= op1;
    case Gt: return op0 > op1;
    case Lt: return op0 < op1;
    case And: return (op0 != 0) && (op1 != 0);
    case Or: return (op0 != 0) || (op1 != 0);
    case Not: return (op0 == 0);
    case Cond:
        if ((op0) && (root->ops[1])) {
            return evaluate_element (root->ops[1], 0);
        } else if ((!op0) && (root->ops[2])) {
            return evaluate_element (root->ops[2], 0);
        } else {
            return 0;
        }
    case While: return while_do (root->ops[0], root->ops[1]);
    case Prog: return program_do (root->ops, root->nbops);
    case Print: return print (op0);
    }

    return 0;
}

char **generate_completion_list ()
{
    int i, j, l = 0;
    char **list = (char **) calloc (NB_OPERATORS + NB_FUNCTIONS + NB_CONSTANTS + NB_SYMBOLS + 1, sizeof (char *));
    if (list == NULL) {
        VERBOSE (ERROR, fprintf (stderr, "can't allocate memory\n"));
        exit (1);
    }

    for (i = 0; i < NB_OPERATORS; i++) {
        list[l] = strdup ((operators + i)->keyword);
        for (j = 0; j < (int)strlen (list[l]); j++) {
            if (list[i][j] == '\t') {
                list[i][j] = '\0';
            }
        }
        if (list[l] != NULL) {
            l++;
        }
    }

    for (i = 0; i < NB_FUNCTIONS; i++) {
        list[l] = strdup ((functions + i)->keyword);
        if (list[l] != NULL) {
            l++;
        }
    }

    for (i = 0; i < NB_CONSTANTS; i++) {
        list[l] = strdup ((constants + i)->keyword);
        if (list[l] != NULL) {
            l++;
        }
    }

    for (i = 0; i < NB_SYMBOLS; i++) {
        list[l] = strdup (symbols[i]);
        if (list[l] != NULL) {
            l++;
        }
    }

    return (list);
}

void free_completion_list (char **list)
{
    int i;

    if (list) {
        for (i = 0; i < NB_FUNCTIONS + NB_CONSTANTS; i++) {
            if (list[i] != NULL) {
                free (list[i]);
            }
        }
        free (list);
    }
}


/* vim: set ts=4 sw=4 et: */