[calc.git] / parser.c

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

#include "debug.h"
#include "fdprintf.h"

#include "parser.h"

/* 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, fdprintf (stdfderr, "can't allocate memory\n"));
        return NULL;
    }
    new->func = function;
    new->nbops = nbops;
    new->prio = prio;

    return new;
}

/* functions */

#define NB_OPERATORS 6

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}
};

#define NB_FUNCTIONS 9
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},
    { "atan", Atn, 1, 4, 5},
    { "exp",  Exp, 1, 3, 5},
    { "log",  Log, 1, 3, 5},
    { "quit", Qui, 0, 4, 5},
    { "help", Hel, 0, 4, 5}
};

/* subparser function */

element_t *subparser (element_t **proot, char **pstr, func_t func, int nbops, int prio)
{
    element_t *new = newelement (func, nbops, prio);
    if (new == NULL) {
        return ERROR_OP;
    }
    new->ops[0] = *proot;
    new->ops[1] = parser (*pstr, pstr, new->prio);
    if (new->ops[1] == ERROR_OP) {
        return ERROR_OP;
    }
    *proot = newelement (Val, 1, 5);
    if (*proot == ERROR_OP) {
        return ERROR_OP;
    }
    (*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, PRINTOUT ("Starting parsing\n"));

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

        /* skip spaces and tabs */

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

        /* check for open bracket */

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

        /* check for closing bracket or koma */

        if ((*str == ')') || (*str == ',')) {
            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, PRINTOUT ("start processing operator\n"));
                if (root) {
                    if ((prio) && (prio > operator->prio)) {
                        VERBOSE (DEBUG, PRINTOUT ("stop because operator priority\n"));
                        *next = str;
                        return root;
                    }
                    str += operator->offset;
                    VERBOSE (INFO, PRINTOUT ("Oper: %d\n", operator->func));
                    if (subparser (&root, &str, operator->func, operator->nbops, operator->prio) == ERROR_OP) {
                        return ERROR_OP;
                    }
                } else if (*str == '-') {
                    new = newelement (Sig, 1, 9);
                    if (new == NULL) {
                        return ERROR_OP;
                    }
                    root = new;
                } else {
                    return ERROR_OP;
                }
                found = 1;
                VERBOSE (DEBUG, PRINTOUT ("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, PRINTOUT ("start processing function\n"));
                if (root == NULL) {
                    VERBOSE (INFO, PRINTOUT ("Func: %d\n", function->func));
                    new = newelement (function->func, function->nbops, function->prio);
                    if (new == NULL) {
                        return ERROR_OP;
                    }
                    root = new;
                 } else {
                    return ERROR_OP;
                }
                str += function->offset;
                found = 1;
                VERBOSE (DEBUG, PRINTOUT ("stop processing function\n"));
                break;
            }
        }
        if (found) {
            continue;
        }

        /* look for number */

        if (((*str >= '0') && (*str <= '9')) ||
            (*str == '.') || (*str == '+') || (*str == '-')) {
            VERBOSE (DEBUG, PRINTOUT ("start processing value\n"));
            char *pt;
            float value = strtof (str, &pt);
            VERBOSE (INFO, PRINTOUT ("Value: %f\n", value));
            if (str != pt) {
                if (root == NULL) {
                    new = newelement (Val, 1, 5);
                    if (new == NULL) {
                        return ERROR_OP;
                    }
                    new->value = value;
                    root = new;
                    str = pt;
                } else if (root->func == Val) {
                    if ((*str == '+') || (*str == '-')) {
                        if ((prio) && (prio > 1)) {
                            VERBOSE (DEBUG, PRINTOUT ("stop because operator priority\n"));
                            *next = str;
                            return root;
                        }
                        if (subparser (&root, &str, Add, 2, 1) == ERROR_OP) {
                            return ERROR_OP;
                        }
                    } else {
                        return ERROR_OP;
                    }
                } else {
                    return ERROR_OP;
                }
                found = 1;
            }
            VERBOSE (DEBUG, PRINTOUT ("stop processing value\n"));
        }

        /* error */

        if (!found) {
            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++) {
        PRINTOUT (" ");
    }

    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 Atn: func = "Arc Tangent"; break;
    case Log: func = "Logarithm"; break;
    case Exp: func = "Exponantial"; break;
    case Qui: func = "Quit"; break;
    case Hel: func = "Help"; break;
    }

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

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

/* quit function */

void quit (void)
{
    PRINTOUT ("bye\n");
    exit (0);
}

/* help message */

void help (void)
{
    PRINTOUT ("calc is a simple calculator\n\n");
    PRINTOUT ("supported operators:\n");
    PRINTOUT (" + - * / % ^\n\n");
    PRINTOUT ("supported functions:\n");
    PRINTOUT (" pow sqrt cos sin atan log exp\n\n");
    PRINTOUT ("miscellaneous functions:\n");
    PRINTOUT (" quit help\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, PRINTOUT ("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:
        if (root->ops[1]) {
            op1 = evaluate_element (root->ops[1], nextmask);
        } else {
            VERBOSE (WARNING, PRINTOUT ("error while evaluating (op[1])\n"));
            return 0;
        }
        /* fallthrough */
    case Sqr:
    case Cos:
    case Sin:
    case Atn:
    case Log:
    case Exp:
        if (root->ops[0]) {
            op0 = evaluate_element (root->ops[0], 0);
        } else {
            VERBOSE (WARNING, PRINTOUT ("error while evaluating (op[0])\n"));
            return 0;
        }
        break;
    case Qui:
    case Hel:
        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 Atn: return atan (op0);
    case Log: return log (op0);
    case Exp: return exp (op0);
    case Qui: quit (); break;
    case Hel: help (); break;
    }

    return 0;
}

/* vim: set ts=4 sw=4 et: */
Commit	Line	Data
bc97a989	1	#include <malloc.h>
f2927108	2	#include <math.h>
bc97a989 LM	3	#include <stdlib.h>
	4
	5	#include "debug.h"
	6	#include "fdprintf.h"
	7
	8	#include "parser.h"
	9
	10	/* compare codes */
	11
	12	int codecmp (char ref, char str)
	13	{
	14	int sig;
	15
	16	while (*ref != '\0') {
0b9cc9b0 LM	17	if (*ref == '\t') {
	18	sig = (str == '.') ? -1 : ((str >= '0') && (*str <= '9'));
	19	} else {
	20	sig = str - ref;
	21	}
bc97a989 LM	22	if (sig != 0) {
	23	return (sig > 0) ? 1 : -1;
	24	}
0b9cc9b0 LM	25	str++;
0b9cc9b0 LM	26	ref++;
bc97a989 LM	27	}
	28
	29	return 0;
	30	}
	31
	32	/* allocate new element */
	33
11cda8d7	34	element_t *newelement (func_t function, int nbops, int prio)
bc97a989 LM	35	{
	36	element_t new = (element_t ) calloc (1, sizeof (element_t));
	37	if (new == NULL) {
	38	VERBOSE (ERROR, fdprintf (stdfderr, "can't allocate memory\n"));
	39	return NULL;
	40	}
	41	new->func = function;
	42	new->nbops = nbops;
11cda8d7	43	new->prio = prio;
bc97a989 LM	44
	45	return new;
	46	}
	47
	48	/* functions */
	49
c47a9298	50	#define NB_OPERATORS 6
bc97a989 LM	51
bc97a989 LM	52	keyword_t operators[NB_OPERATORS] = {
11cda8d7 LM	53	{ "+\t", Add, 2, 1, 1},
	54	{ "-\t", Sub, 2, 1, 1},
	55	{ "*", Mul, 2, 1, 2},
	56	{ "/", Div, 2, 1, 2},
c47a9298 LM	57	{ "%", Mod, 2, 1, 3},
c47a9298 LM	58	{ "^", Pow, 2, 1, 4}
bc97a989 LM	59	};
bc97a989 LM	60
89cf0955	61	#define NB_FUNCTIONS 9
bc97a989	62	keyword_t functions[NB_FUNCTIONS] = {
c47a9298 LM	63	{ "sqrt", Sqr, 1, 4, 5},
	64	{ "pow", Pow, 2, 3, 5},
	65	{ "cos", Cos, 1, 3, 5},
	66	{ "sin", Sin, 1, 3, 5},
	67	{ "atan", Atn, 1, 4, 5},
	68	{ "exp", Exp, 1, 3, 5},
89cf0955 LM	69	{ "log", Log, 1, 3, 5},
	70	{ "quit", Qui, 0, 4, 5},
	71	{ "help", Hel, 0, 4, 5}
bc97a989 LM	72	};
bc97a989 LM	73
d2ff8478 LM	74	/* subparser function */
	75
	76	element_t subparser (element_t proot, char *pstr, func_t func, int nbops, int prio)
	77	{
	78	element_t *new = newelement (func, nbops, prio);
	79	if (new == NULL) {
	80	return ERROR_OP;
	81	}
	82	new->ops[0] = *proot;
	83	new->ops[1] = parser (*pstr, pstr, new->prio);
	84	if (new->ops[1] == ERROR_OP) {
	85	return ERROR_OP;
	86	}
3b4b0bbe	87	*proot = newelement (Val, 1, 5);
d2ff8478 LM	88	if (*proot == ERROR_OP) {
	89	return ERROR_OP;
	90	}
	91	(*proot)->ops[0] = new;
	92
	93	return *proot;
	94	}
	95
bc97a989 LM	96	/* parser function */
bc97a989 LM	97
ef37d966	98	element_t parser (char str, char **next, int prio)
0b489a77	99	{
bc97a989	100	element_t *root = NULL;
85b4a72c	101	int i;
bc97a989	102
49223129 LM	103	VERBOSE (DEBUG, PRINTOUT ("Starting parsing\n"));
49223129 LM	104
bc97a989 LM	105	/* main loop */
	106	while (*str != '\0') {
	107	int found = 0;
	108	element_t *new = NULL;
49223129	109	VERBOSE (INFO, PRINTOUT ("Processing: %s\n", str));
bc97a989 LM	110
	111	/* skip spaces and tabs */
	112
	113	if ((str == ' ') \|\| (str == '\t')) {
	114	str++;
	115	continue;
	116	}
	117
85b4a72c	118	/* check for open bracket */
0b489a77	119
0b489a77	120	if (*str == '(') {
49223129	121	VERBOSE (DEBUG, PRINTOUT ("start processing bracket\n"));
0b489a77	122	if (root) {
85b4a72c LM	123	do {
85b4a72c LM	124	found = 0;
ef37d966	125	new = parser (str + 1, &str, 0);
85b4a72c LM	126	if (new == ERROR_OP) {
	127	return ERROR_OP;
	128	}
	129	for (i = 0; i < root->nbops; i++) {
	130	if (root->ops[i] == NULL) {
0b489a77 LM	131	root->ops[i] = new;
	132	found = 1;
	133	break;
	134	}
	135	}
85b4a72c LM	136	if (!found) {
	137	return ERROR_OP;
	138	}
	139	} while (*str == ',');
	140	} else {
3b4b0bbe	141	root = newelement (Val, 1, 5);
85b4a72c	142	if (root == NULL) {
0b489a77 LM	143	return ERROR_OP;
0b489a77 LM	144	}
ef37d966	145	new = parser (str + 1, &str, 0);
85b4a72c	146	if ((new == ERROR_OP) \|\| (*str == ',')) {
efdfb543 LM	147	return ERROR_OP;
efdfb543 LM	148	}
85b4a72c	149	root->ops[0] = new;
0b489a77	150	}
85b4a72c	151	str++;
49223129	152	VERBOSE (DEBUG, PRINTOUT ("stop processing bracket\n"));
efdfb543	153	continue;
49223129	154	}
85b4a72c LM	155
	156	/* check for closing bracket or koma */
	157
	158	if ((str == ')') \|\| (str == ',')) {
49223129	159	if (next != NULL) {
85b4a72c	160	*next = str;
49223129 LM	161	}
49223129 LM	162	return root;
0b489a77 LM	163	}
0b489a77 LM	164
bc97a989 LM	165	/* look for operators */
	166
	167	for (i = 0; i < NB_OPERATORS; i++) {
	168	keyword_t *operator = operators + i;
	169	if (codecmp (operator->keyword, str) == 0) {
49223129	170	VERBOSE (DEBUG, PRINTOUT ("start processing operator\n"));
11cda8d7	171	if (root) {
ef37d966	172	if ((prio) && (prio > operator->prio)) {
c47a9298	173	VERBOSE (DEBUG, PRINTOUT ("stop because operator priority\n"));
ef37d966 LM	174	*next = str;
	175	return root;
	176	}
	177	str += operator->offset;
49223129	178	VERBOSE (INFO, PRINTOUT ("Oper: %d\n", operator->func));
d2ff8478	179	if (subparser (&root, &str, operator->func, operator->nbops, operator->prio) == ERROR_OP) {
ef37d966	180	return ERROR_OP;
11cda8d7	181	}
3b4b0bbe LM	182	} else if (*str == '-') {
	183	new = newelement (Sig, 1, 9);
	184	if (new == NULL) {
	185	return ERROR_OP;
	186	}
	187	root = new;
49223129	188	} else {
0b489a77	189	return ERROR_OP;
bc97a989	190	}
bc97a989	191	found = 1;
49223129	192	VERBOSE (DEBUG, PRINTOUT ("stop processing operator\n"));
bc97a989 LM	193	break;
	194	}
	195	}
	196	if (found) {
bc97a989 LM	197	continue;
bc97a989 LM	198	}
49223129	199
bc97a989 LM	200	/* look for functions */
	201
	202	for (i = 0; i < NB_FUNCTIONS; i++) {
	203	keyword_t *function = functions + i;
	204	if (codecmp (function->keyword, str) == 0) {
49223129	205	VERBOSE (DEBUG, PRINTOUT ("start processing function\n"));
bc97a989	206	if (root == NULL) {
49223129	207	VERBOSE (INFO, PRINTOUT ("Func: %d\n", function->func));
11cda8d7	208	new = newelement (function->func, function->nbops, function->prio);
bc97a989	209	if (new == NULL) {
0b489a77	210	return ERROR_OP;
bc97a989 LM	211	}
	212	root = new;
	213	} else {
0b489a77	214	return ERROR_OP;
bc97a989 LM	215	}
	216	str += function->offset;
	217	found = 1;
49223129	218	VERBOSE (DEBUG, PRINTOUT ("stop processing function\n"));
bc97a989 LM	219	break;
	220	}
	221	}
	222	if (found) {
bc97a989 LM	223	continue;
	224	}
	225
bc97a989 LM	226	/* look for number */
bc97a989 LM	227
0b9cc9b0 LM	228	if (((str >= '0') && (str <= '9')) \|\|
0b9cc9b0 LM	229	(str == '.') \|\| (str == '+') \|\| (*str == '-')) {
49223129	230	VERBOSE (DEBUG, PRINTOUT ("start processing value\n"));
bc97a989 LM	231	char *pt;
bc97a989 LM	232	float value = strtof (str, &pt);
49223129	233	VERBOSE (INFO, PRINTOUT ("Value: %f\n", value));
bc97a989	234	if (str != pt) {
bc97a989	235	if (root == NULL) {
3b4b0bbe	236	new = newelement (Val, 1, 5);
c47a9298 LM	237	if (new == NULL) {
	238	return ERROR_OP;
	239	}
	240	new->value = value;
bc97a989	241	root = new;
c47a9298	242	str = pt;
0b9cc9b0 LM	243	} else if (root->func == Val) {
0b9cc9b0 LM	244	if ((str == '+') \|\| (str == '-')) {
c47a9298 LM	245	if ((prio) && (prio > 1)) {
	246	VERBOSE (DEBUG, PRINTOUT ("stop because operator priority\n"));
	247	*next = str;
	248	return root;
	249	}
d2ff8478	250	if (subparser (&root, &str, Add, 2, 1) == ERROR_OP) {
0b489a77 LM	251	return ERROR_OP;
0b489a77 LM	252	}
0b9cc9b0	253	} else {
0b489a77	254	return ERROR_OP;
bc97a989	255	}
0b9cc9b0 LM	256	} else {
0b9cc9b0 LM	257	return ERROR_OP;
bc97a989	258	}
bc97a989 LM	259	found = 1;
bc97a989 LM	260	}
49223129	261	VERBOSE (DEBUG, PRINTOUT ("stop processing value\n"));
bc97a989 LM	262	}
	263
	264	/* error */
	265
	266	if (!found) {
0b489a77	267	return ERROR_OP;
bc97a989 LM	268	}
	269
	270	}
	271
49223129 LM	272	if (next != NULL) {
	273	*next = str;
	274	}
bc97a989 LM	275	return root;
	276	}
	277
	278	/* print element tree */
	279
	280	void print_element (element_t *root, int level)
	281	{
	282	char *func = NULL;
	283	int i;
	284
49223129	285	if ((root == NULL) \|\| (root == ERROR_OP)) {
bc97a989	286	return;
49223129 LM	287	}
49223129 LM	288
bc97a989 LM	289	for (i = 0; i < level; i++) {
	290	PRINTOUT (" ");
	291	}
	292
	293	switch (root->func) {
	294	case Val: func = "Value"; break;
89cf0955	295	case Sig: func = "Sign"; break;
bc97a989 LM	296	case Add: func = "Addition"; break;
	297	case Sub: func = "Subtraction"; break;
	298	case Mul: func = "Multiplication"; break;
	299	case Div: func = "Division"; break;
c47a9298	300	case Mod: func = "Modulo"; break;
bc97a989 LM	301	case Pow: func = "Power"; break;
	302	case Sqr: func = "Square Root"; break;
	303	case Cos: func = "Cosine"; break;
	304	case Sin: func = "Sine"; break;
	305	case Atn: func = "Arc Tangent"; break;
	306	case Log: func = "Logarithm"; break;
	307	case Exp: func = "Exponantial"; break;
89cf0955 LM	308	case Qui: func = "Quit"; break;
89cf0955 LM	309	case Hel: func = "Help"; break;
bc97a989 LM	310	}
	311
	312	PRINTOUT ("Function: %s\n", func);
	313
85b4a72c	314	if ((root->func == Val) && (root->ops[0] == NULL)) {
bc97a989 LM	315	for (i = 0; i < level; i++) {
	316	PRINTOUT (" ");
	317	}
	318	PRINTOUT ("value: %f\n", root->value);
	319	} else {
	320	for (i = 0; i < root->nbops; i++) {
	321	print_element (root->ops[i], level + 1);
	322	}
	323	}
	324	}
	325
89cf0955 LM	326	/* quit function */
	327
	328	void quit (void)
	329	{
	330	PRINTOUT ("bye\n");
	331	exit (0);
	332	}
	333
	334	/* help message */
	335
	336	void help (void)
	337	{
	338	PRINTOUT ("calc is a simple calculator\n\n");
	339	PRINTOUT ("supported operators:\n");
	340	PRINTOUT (" + - * / % ^\n\n");
	341	PRINTOUT ("supported functions:\n");
	342	PRINTOUT (" pow sqrt cos sin atan log exp\n\n");
	343	PRINTOUT ("miscellaneous functions:\n");
	344	PRINTOUT (" quit help\n");
	345	}
3b4b0bbe	346
f2927108 LM	347	/* evaluate element tree */
f2927108 LM	348
89cf0955 LM	349	#define MASK_SUB 0x1
	350	#define MASK_DIV 0x2
	351
3b4b0bbe	352	double evaluate_element (element_t *root, char mask)
f2927108 LM	353	{
f2927108 LM	354	double op0 = 0, op1 = 0;
3b4b0bbe	355	char nextmask = mask;
f2927108 LM	356
	357	if ((root == NULL) \|\| (root == ERROR_OP)) {
	358	VERBOSE (WARNING, PRINTOUT ("error while evaluating\n"));
	359	return 0;
	360	}
	361
3b4b0bbe LM	362	/* mask to manage sub operator sub and div */
	363	switch (root->func) {
	364	case Add:
	365	nextmask &= ~MASK_SUB;
	366	nextmask &= ~MASK_DIV;
	367	break;
	368	case Sub:
	369	nextmask \|= MASK_SUB;
	370	nextmask &= ~MASK_DIV;
	371	break;
	372	case Mul:
	373	nextmask &= ~MASK_DIV;
	374	break;
	375	case Div:
	376	nextmask \|= MASK_DIV;
	377	break;
	378	default:
	379	nextmask = mask;
	380	}
	381
f2927108 LM	382	switch (root->func) {
f2927108 LM	383	case Val:
3b4b0bbe LM	384	case Sig:
3b4b0bbe LM	385	op0 = (root->ops[0]) ? evaluate_element (root->ops[0], nextmask) : root->value;
f2927108 LM	386	break;
	387	case Add:
	388	case Sub:
	389	case Mul:
	390	case Div:
c47a9298	391	case Mod:
f2927108 LM	392	case Pow:
f2927108 LM	393	if (root->ops[1]) {
3b4b0bbe	394	op1 = evaluate_element (root->ops[1], nextmask);
f2927108 LM	395	} else {
	396	VERBOSE (WARNING, PRINTOUT ("error while evaluating (op[1])\n"));
	397	return 0;
	398	}
	399	/* fallthrough */
	400	case Sqr:
	401	case Cos:
	402	case Sin:
	403	case Atn:
	404	case Log:
	405	case Exp:
	406	if (root->ops[0]) {
3b4b0bbe	407	op0 = evaluate_element (root->ops[0], 0);
f2927108 LM	408	} else {
	409	VERBOSE (WARNING, PRINTOUT ("error while evaluating (op[0])\n"));
	410	return 0;
	411	}
89cf0955 LM	412	break;
	413	case Qui:
	414	case Hel:
	415	break;
f2927108 LM	416	}
	417
	418	switch (root->func) {
3b4b0bbe LM	419	case Val: return op0;
	420	case Sig: return -op0;
	421	case Add: return ((mask & MASK_SUB) == 0) ? op0 + op1 : op0 - op1;
	422	case Sub: return ((mask & MASK_SUB) == 0) ? op0 - op1 : op0 + op1;
	423	case Mul: return ((mask & MASK_DIV) == 0) ? op0 * op1 : op0 / op1;
	424	case Div: return ((mask & MASK_DIV) == 0) ? op0 / op1 : op0 * op1;
c47a9298	425	case Mod: return fmod (op0, op1);
f2927108 LM	426	case Pow: return pow (op0, op1);
	427	case Sqr: return sqrt (op0);
	428	case Cos: return cos (op0);
	429	case Sin: return sin (op0);
	430	case Atn: return atan (op0);
	431	case Log: return log (op0);
	432	case Exp: return exp (op0);
89cf0955 LM	433	case Qui: quit (); break;
89cf0955 LM	434	case Hel: help (); break;
f2927108 LM	435	}
	436
	437	return 0;
	438	}
	439
bc97a989	440	/* vim: set ts=4 sw=4 et: */