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/*
* HardInfo - Displays System Information
* Copyright (C) 2003-2007 L. A. F. Pereira <l@tia.mat.br>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/*
* This is only used to compute sensor values, hence the only variable supported is '@'.
* The '`' operator (ln(x)) is not available, nor multi-line formulas.
*/
#include <glib.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include <math.h>
#include "expr.h"
#include "config.h"
static MathToken *new_operator(gchar op)
{
MathToken *t = g_new0(MathToken, 1);
t->val.op = op;
t->type = TOKEN_OPERATOR; /* operator */
return t;
}
static MathToken *new_variable(gchar var)
{
MathToken *t = g_new0(MathToken, 1);
t->val.op = '@';
t->type = TOKEN_VARIABLE; /* variable */
return t;
}
static MathToken *new_value(gfloat value)
{
MathToken *t = g_new0(MathToken, 1);
t->val.value = value;
t->type = TOKEN_VALUE; /* value */
return t;
}
static inline gint priority(char operation)
{
switch (operation) {
case '^':
return 3;
case '*':
case '/':
return 2;
case '+':
case '-':
return 1;
case '(':
return 0;
}
return 0;
}
GSList *math_infix_to_postfix(GSList * infix)
{
MathToken *stack[500];
gint t_sp = 0;
GSList *postfix = NULL, *p;
MathToken *top;
for (p = infix; p; p = p->next) {
MathToken *t = (MathToken *) p->data;
if (t->type == TOKEN_OPERATOR && t->val.op == '(') {
stack[++t_sp] = t;
} else if (t->type == TOKEN_OPERATOR && t->val.op == ')') {
for (top = stack[t_sp]; t_sp != 0 && top->val.op != '(';
top = stack[t_sp]) {
postfix = g_slist_append(postfix, stack[t_sp--]);
}
t_sp--;
} else if (t->type != TOKEN_OPERATOR) {
postfix = g_slist_append(postfix, t);
} else if (t_sp == 0) {
stack[++t_sp] = t;
} else {
while (t_sp != 0
&& priority(t->val.op) <= priority(stack[t_sp]->val.op))
postfix = g_slist_append(postfix, stack[t_sp--]);
stack[++t_sp] = t;
}
}
while (t_sp)
postfix = g_slist_append(postfix, stack[t_sp--]);
return postfix;
}
static inline gfloat __result(gfloat op1, gfloat op2, gchar operation)
{
switch (operation) {
case '^':
return powf(op1, op2);
case '+':
return op1 + op2;
case '-':
return op1 - op2;
case '/':
return op1 / op2;
case '*':
return op1 * op2;
}
return 0;
}
gfloat math_postfix_eval(GSList * postfix, gfloat at_value)
{
GSList *p;
gfloat stack[500];
gint sp = 0;
memset(stack, 0, sizeof(gfloat) * 500);
for (p = postfix; p; p = p->next) {
MathToken *t = (MathToken *) p->data;
if (t->type == TOKEN_VARIABLE) {
stack[++sp] = at_value;
} else if (t->type == TOKEN_VALUE) {
stack[++sp] = t->val.value;
} else {
gfloat op1, op2;
op2 = stack[sp--];
op1 = stack[sp];
stack[sp] = __result(op1, op2, t->val.op);
}
}
return stack[sp];
}
GSList *math_string_to_infix(gchar * string)
{
GSList *infix = NULL;
gchar *expr = string;
for (; *expr; expr++) {
if (strchr("+-/*^()", *expr)) {
infix = g_slist_append(infix, new_operator(*expr));
} else if (strchr("@", *expr)) {
infix = g_slist_append(infix, new_variable(*expr));
} else if (strchr("-.1234567890", *expr)) {
gchar value[32], *v = value;
gfloat floatval;
do {
*v++ = *expr++;
} while (*expr && strchr("-.1234567890", *expr));
expr--;
*v = '\0';
sscanf(value, "%f", &floatval);
infix = g_slist_append(infix, new_value(floatval));
} else if (!isspace(*expr)) {
g_print("Invalid token: [%c][%d]\n", *expr, *expr);
math_infix_free(infix, TRUE);
return NULL;
}
}
return infix;
}
void math_infix_free(GSList * infix, gboolean free_tokens)
{
GSList *p;
if (!free_tokens)
for (p = infix; p; p = g_slist_delete_link(p, p));
else
for (p = infix; p; p = g_slist_delete_link(p, p)) {
MathToken *t = (MathToken *) p->data;
g_free(t);
}
}
GSList *math_string_to_postfix(gchar * string)
{
GSList *infix;
GSList *postfix;
infix = math_string_to_infix(string);
if (!infix)
return NULL;
postfix = math_infix_to_postfix(infix);
math_infix_free(infix, FALSE);
return postfix;
}
gfloat math_string_eval(gchar * string, gfloat at_value)
{
GSList *postfix;
gfloat val;
postfix = math_string_to_postfix(string);
val = math_postfix_eval(postfix, at_value);
math_postfix_free(postfix, TRUE);
return val;
}
#ifdef MATH_TEST
int main(void)
{
GSList *postfix;
gchar *expr = "0.9*(@+(5.2*0.923+3*(2.0)))";
postfix = math_string_to_postfix(expr);
g_print("%s = %f (must be 18.71964)\n", expr,
math_postfix_eval(postfix, 10));
math_postfix_free(postfix, TRUE);
return 0;
}
#endif
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