public function testInsertAndRemove()
{
$Stack = new Stack();
$Stack->push('Radig');
$this->assertIdentical($Stack->size(), 1);
$this->assertIdentical($Stack->nth(), 'Radig');
$Stack->push('CakePHP');
$this->assertIdentical($Stack->size(), 2);
// testa com 1-lookahead
$this->assertIdentical($Stack->nth(), 'CakePHP');
// teste com 2-lookahead
$this->assertIdentical($Stack->nth(2), 'Radig');
$this->assertIdentical($Stack->pop(), 'CakePHP');
$this->assertIdentical($Stack->pop(), 'Radig');
$this->assertIdentical($Stack->pop(), null);
unset($Stack);
}
/**
* Evaluate postfix notation
*
* @param array $tokens
* @param array $vars
*
* @return mixed boolean *false* in failures and *numeric* value in success
*/
protected function pfx($tokens, $vars = array())
{
bcscale($this->precision);
if ($tokens === false) {
return false;
}
$stack = new Stack();
foreach ($tokens as $token) {
// if the token is a binary operator, pop two values off the stack, do the operation, and push the result back on
if (in_array($token, array('+', '-', '*', '/', '^'))) {
if (is_null($op2 = $stack->pop()) || is_null($op1 = $stack->pop())) {
return $this->error("Internal error");
}
switch ($token) {
case '+':
$stack->push(bcadd($op1, $op2));
break;
case '-':
$stack->push(bcsub($op1, $op2));
break;
case '*':
$stack->push(bcmul($op1, $op2));
break;
case '/':
if ($op2 == 0) {
return $this->error("Division by zero");
}
$stack->push(bcdiv($op1, $op2));
break;
case '^':
$stack->push(bcpow($op1, $op2));
break;
}
// if the token is a unary operator, pop one value off the stack, do the operation, and push it back on
} elseif ($token == "_") {
// if the token is a function, pop arguments off the stack, hand them to the function, and push the result back on
$stack->push(-1 * $stack->pop());
} elseif (preg_match("/^([a-z]\\w*)\\(\$/", $token, $matches)) {
// it's a function!
$fnn = $matches[1];
// built-in function:
if (in_array($fnn, $this->fb)) {
if (is_null($op1 = $stack->pop())) {
return $this->error("Internal error");
}
// for the 'arc' trig synonyms
$fnn = preg_replace("/^arc/", "a", $fnn);
if ($fnn == 'ln') {
$fnn = 'log';
}
if ($fnn == 'sqrt') {
$fnn = 'bcsqrt';
}
$val = $this->strictPrecision(call_user_func($fnn, $op1));
$stack->push($val);
} elseif (array_key_exists($fnn, $this->f)) {
// get args
$args = array();
for ($i = count($this->f[$fnn]['args']) - 1; $i >= 0; $i--) {
if (is_null($args[$this->f[$fnn]['args'][$i]] = $stack->pop())) {
return $this->error("Internal error");
}
}
$stack->push($this->pfx($this->f[$fnn]['func'], $args));
// yay... recursion!!!!
}
} else {
if (is_numeric($token)) {
$stack->push($this->strictPrecision($token));
} elseif (array_key_exists($token, $this->v)) {
$stack->push($this->strictPrecision($this->v[$token]));
} elseif (array_key_exists($token, $vars)) {
$stack->push($this->strictPrecision($vars[$token]));
} else {
return $this->error("Undefined variable '{$token}'");
}
}
}
// when we're out of tokens, the stack should have a single element, the final result
if ($stack->size() != 1) {
return $this->error("Internal error");
}
return $stack->pop();
}
