quakeforge/libs/util/exp.c

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/*
EXP equation evaluation routines
Copyright (C) 2000, 2001 Brian Koropoff
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; either version 2
of the License, or (at your option) any later version.
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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, US
*/
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <stdio.h>
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#include "QF/exp.h"
#include "QF/ops.h"
#include "QF/qtypes.h"
exp_error_t EXP_ERROR;
optable_t optable[] =
{
{"**", OP_Exp},
{"/", OP_Div},
{"*", OP_Mult},
{"+", OP_Add},
{"-", OP_Sub},
{"==", OP_Eq},
{"!=", OP_Neq},
{">=", OP_GreaterThanEqual},
{">", OP_GreaterThan},
{"<=", OP_LessThanEqual},
{"<", OP_LessThan},
{"||", OP_Or},
{"&&", OP_And},
{"", 0}
};
token *EXP_NewToken (void)
{
token *new;
new = malloc(sizeof(token));
if (!new)
return 0;
new->generic.type = TOKEN_GENERIC;
return new;
}
token *EXP_ParseString (char *str)
{
char buf[256];
token *chain, *new, *cur;
int i,n,m;
cur = chain = EXP_NewToken();
chain->generic.type = TOKEN_OPAREN;
chain->generic.prev = 0;
chain->generic.next = 0;
for (i = 0; i < strlen(str); i++)
{
m = 0;
while(str[i] == ' ')
i++;
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if (isdigit((byte)str[i]) || str[i] == '.')
{
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while ((isdigit((byte)str[i]) || str[i] == '.') && i < strlen(str) && m < 256)
buf[m++] = str[i++];
buf[m] = 0;
new = EXP_NewToken();
new->generic.type = TOKEN_NUM;
new->num.value = atof(buf);
new->generic.prev = cur;
new->generic.next = 0;
cur->generic.next = new;
cur = new;
i--;
}
else if (str[i] == '(')
{
new = EXP_NewToken();
new->generic.type = TOKEN_OPAREN;
new->generic.prev = cur;
new->generic.next = 0;
cur->generic.next = new;
cur = new;
}
else if (str[i] == ')')
{
new = EXP_NewToken();
new->generic.type = TOKEN_CPAREN;
new->generic.prev = cur;
new->generic.next = 0;
cur->generic.next = new;
cur = new;
}
else
{
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while(!(isdigit((byte)str[i])) && str[i] != '.' && str[i] != '(' && str[i] != ')' && m < 256)
buf[m++] = str[i++];
buf[m] = 0;
if (m)
{
for (n = 0; optable[n].func; n++)
{
if (!(strncmp(optable[n].str, buf, strlen(optable[n].str))))
{
i -= (m - strlen(optable[n].str) + 1);
new = EXP_NewToken();
new->generic.type = TOKEN_OP;
new->op.func = optable[n].func;
new->generic.prev = cur;
new->generic.next = 0;
cur->generic.next = new;
cur = new;
break;
}
}
if (!(optable[n].func)) {
EXP_DestroyTokens (chain);
return 0;
}
}
}
}
new = EXP_NewToken();
new->generic.type = TOKEN_CPAREN;
new->generic.prev = cur;
new->generic.next = 0;
cur->generic.next = new;
return chain;
}
void EXP_SimplifyTokens (token *chain)
{
int i;
token *cur;
token *temp;
/* First, get rid of parentheses */
for (cur = chain->generic.next; cur->generic.type != TOKEN_CPAREN; cur = cur->generic.next)
{
if (cur->generic.type == TOKEN_OPAREN)
{
EXP_SimplifyTokens(cur); /* Call ourself to simplify parentheses content */
temp = cur;
cur = cur->generic.next;
EXP_RemoveToken(temp); /* Remove parentheses, leaving value behind */
EXP_RemoveToken(cur->generic.next);
}
}
/* Next, evaluate all operators in order of operations */
for (i = 0; optable[i].func; i++)
{
for (cur = chain->generic.next; cur->generic.type != TOKEN_CPAREN; cur = cur->generic.next)
{
if (cur->generic.type == TOKEN_OP && cur->op.func == optable[i].func && cur->generic.next)
if (cur->generic.prev->generic.type == TOKEN_NUM && cur->generic.next->generic.type == TOKEN_NUM)
{
cur->generic.prev->num.value = optable[i].func(cur->generic.prev->num.value, cur->generic.next->num.value);
temp = cur;
cur = cur->generic.prev;
EXP_RemoveToken(temp->generic.next);
EXP_RemoveToken(temp);
}
}
}
}
void EXP_RemoveToken (token *tok)
{
tok->generic.prev->generic.next = tok->generic.next;
tok->generic.next->generic.prev = tok->generic.prev;
free(tok);
}
void EXP_DestroyTokens (token *chain)
{
token *temp;
for (;chain; chain = temp)
{
temp = chain->generic.next;
free(chain);
}
}
float EXP_Evaluate (char *str)
{
token *chain;
float res;
EXP_ERROR = EXP_E_NORMAL;
if (!(chain = EXP_ParseString (str)))
{
EXP_ERROR = EXP_E_PARSE;
return 0;
}
res = EXP_Validate (chain);
if (res)
{
EXP_DestroyTokens (chain);
EXP_ERROR = res;
return 0;
}
EXP_SimplifyTokens (chain);
res = chain->generic.next->num.value;
EXP_DestroyTokens (chain);
return res;
}
void EXP_InsertTokenAfter (token *spot, token *new)
{
spot->generic.next->generic.prev = new;
new->generic.next = spot->generic.next;
new->generic.prev = spot;
spot->generic.next = new;
}
exp_error_t EXP_Validate (token *chain)
{
token *cur, *new;
int paren = 0;
for (cur = chain; cur->generic.next; cur = cur->generic.next)
{
if (cur->generic.type == TOKEN_OPAREN)
paren++;
if (cur->generic.type == TOKEN_CPAREN)
paren--;
/* Implied multiplication */
if ((cur->generic.type == TOKEN_NUM && cur->generic.next->generic.type == TOKEN_OPAREN) || /* 5(1+1) */
(cur->generic.type == TOKEN_CPAREN && cur->generic.next->generic.type == TOKEN_NUM) || /* (1+1)5 */
(cur->generic.type == TOKEN_CPAREN && cur->generic.next->generic.type == TOKEN_OPAREN)) /* (1+1)(1+1) */
{
new = EXP_NewToken ();
new->generic.type = TOKEN_OP;
new->op.func = OP_Mult;
EXP_InsertTokenAfter (cur, new);
}
if ((cur->generic.type == TOKEN_OP || cur->generic.type == TOKEN_OPAREN) && cur->generic.next->generic.type == TOKEN_OP)
{
if (cur->generic.next->op.func == OP_Sub) /* Stupid hack for negation */
{
cur = cur->generic.next;
cur->generic.type = TOKEN_NUM;
cur->num.value = -1.0;
new = EXP_NewToken();
new->generic.type = TOKEN_OP;
new->op.func = OP_Mult;
EXP_InsertTokenAfter (cur, new);
}
else
return EXP_E_SYNTAX; /* Operator misuse */
}
else if (cur->generic.type == TOKEN_OP && cur->generic.next->generic.type == TOKEN_CPAREN)
return EXP_E_SYNTAX; /* Missing operand */
else if (cur->generic.type == TOKEN_NUM && cur->generic.next->generic.type == TOKEN_NUM)
return EXP_E_SYNTAX; /* Double number error */
else if (cur->generic.type == TOKEN_OPAREN && cur->generic.next->generic.type == TOKEN_CPAREN)
return EXP_E_PAREN; /* Pointless parentheses */
}
paren--;
if (paren)
return EXP_E_PAREN; /* Paren mismatch */
return 0;
}
void EXP_PrintTokens (token *chain)
{
int m;
for (; chain; chain = chain->generic.next)
switch (chain->generic.type)
{
case TOKEN_OPAREN:
printf("(");
break;
case TOKEN_CPAREN:
printf(")");
break;
case TOKEN_NUM:
printf("%f", chain->num.value);
break;
case TOKEN_OP:
for (m = 0; optable[m].func != chain->op.func; m++);
printf("%s", optable[m].str);
case TOKEN_GENERIC:
break;
}
}