/*
call parse_expsimple() repeatedly until the entire symbol stack is reduced
to a single numeric symbol.
*/
double
ModCalc::parse_explist (void)
{
while (error[0] == 0)
if (parse_expsimple ())
{
symbol_type *symbol = pop_symbol ();
if (symbol == NULL || symbol->type != S_NUM)
{
snprintf (error, MSG_SIZE, "FUNCTION PARAMETER ERROR!");
break;
}
return symbol->value;
}
return 0;
}
/*
parse a simple expression (<num><operation><num>) from the symbol stack
and push the result. expands <num> to identifiers (constants, variables or
functions), and to another expression inside braces.
return 1 if S_EOF is found, 0 otherwise.
*/
bool
ModCalc::parse_expsimple (void)
{
double d = 0;
bool lvalue = 0;
symbol_type *symbol, *op = NULL, *var = NULL;
while (1)
{
symbol = pop_symbol ();
if (symbol == NULL)
{
snprintf (error, MSG_SIZE, "STACK ERROR!");
error_pos = 0;
return 0;
}
error_pos = symbol->pos;
if (symbol->type == S_EOF)
{
if (!lvalue || op != NULL || braces != 0)
{
snprintf (error, MSG_SIZE, "unexpected end of expression");
break;
}
push_symbol (new symbol_type (symbol->pos, d));
delete symbol;
return 1;
}
else if (symbol->type == S_OP)
{
if (symbol->op == OP_ASSIGN)
{
if (var == NULL)
{
snprintf (error, MSG_SIZE, "non-variable lvalue in assignment");
break;
}
}
else
{
if (op != NULL ||
(!lvalue && symbol->op != OP_PLUS && symbol->op != OP_MINUS))
{
if (op != NULL)
snprintf (error, MSG_SIZE, "missing rvalue for operator");
else
snprintf (error, MSG_SIZE, "missing lvalue for operator");
break;
}
if (!lvalue && (symbol->op == OP_PLUS || symbol->op == OP_MINUS))
{
d = 0;
lvalue = 1;
}
}
op = symbol;
}
else if (symbol->type == S_NUM)
{
if (op == NULL)
{
if (lvalue)
{
snprintf (error, MSG_SIZE, "two consecutive values");
break;
}
d = symbol->value;
lvalue = 1;
delete symbol;
continue;
}
if (top != NULL && top->type == S_OP && top->priority > op->priority)
{
push_symbol (new symbol_type (symbol->pos, symbol->value));
parse_expsimple ();
if (error[0] != 0)
break;
delete symbol;
continue;
}
switch (op->op)
{
case OP_ASSIGN:
d = symbol->value;
var_type *v;
vars.rewind ();
while ((v = (var_type *)vars.next ()) != NULL)
if (var->id == v->name)
break;
if (v != NULL)
{
v->value = d;
v->time = get_time ();
}
else
{
vars.add ((void *)new var_type (var->id, d));
if (vars.count () == VARS_MAX)
{
time_t t_old = -1;
var_type *v_old = NULL;
vars.rewind ();
while ((v = (var_type *)vars.next ()) != NULL)
if (v->time < t_old)
{
t_old = v->time;
v_old = v;
}
vars.del ((void *)v_old);
}
}
delete var;
var = NULL;
break;
case OP_PLUS:
d += symbol->value;
break;
case OP_MINUS:
d -= symbol->value;
break;
case OP_TIMES:
d *= symbol->value;
break;
case OP_DIV:
d /= symbol->value;
break;
case OP_MOD:
d = fmod (d, symbol->value);
break;
case OP_POW:
d = pow (d, symbol->value);
break;
case OP_SHIFT_L:
d = ((unsigned long int)d) << ((unsigned long int)symbol->value);
break;
case OP_SHIFT_R:
d = ((unsigned long int)d) >> ((unsigned long int)symbol->value);
break;
case OP_AND:
d = ((unsigned long int)d) & ((unsigned long int)symbol->value);
break;
case OP_OR:
d = ((unsigned long int)d) | ((unsigned long int)symbol->value);
break;
}
push_symbol (new symbol_type (symbol->pos, d));
delete op;
delete symbol;
return 0;
}
else if (symbol->type == S_BRACE_L)
{
int old_braces = braces;
braces++;
while (braces != old_braces)
{
parse_expsimple ();
if (error[0] != 0)
break;
}
delete symbol;
}
else if (symbol->type == S_BRACE_R)
{
if (!lvalue)
snprintf (error, MSG_SIZE, "missing value in braces");
else if (op != NULL)
snprintf (error, MSG_SIZE, "missing rvalue for operator");
else if (braces == 0)
snprintf (error, MSG_SIZE, "extra ')' used");
else
{
braces--;
push_symbol (new symbol_type (symbol->pos, d));
delete symbol;
if (op != NULL)
delete op;
return 0;
}
break;
}
else if (symbol->type == S_ID)
{
if (parse_exp_id (symbol))
{
if (lvalue)
{
snprintf (error, MSG_SIZE, "invalid lvalue in assignment");
break;
}
var = symbol;
}
if (error[0] != 0)
break;
}
}
void clear_table(void)
{
_symbol *entry;
while ((entry = pop_symbol())) clear_entry(entry);
}
