private function parseOperatorToken($firstChar)
{
$offset = $this->pos;
$len = 1;
$symbol = "";
$lastValid = null;
$symbol .= $firstChar;
while (!$this->isEndOfExpression($offset + $len) && Operator::isAllowedOperatorChar($this->expression[$offset + $len])) {
$symbol .= $this->expression[$offset + $len++];
}
while (strlen($symbol) > 0) {
$op = $this->getOperator($symbol);
if ($op == null) {
$symbol = substr($symbol, 0, strlen($symbol) - 1);
} else {
$lastValid = $op;
break;
}
}
$this->pos += strlen($symbol);
$this->lastToken = new OperatorToken($lastValid);
return $this->lastToken;
}
private function checkOperatorSymbol($op)
{
$name = $op->getSymbol();
foreach (str_split($name) as $ch) {
if (!Operator::isAllowedOperatorChar($ch)) {
throw new ExpressionException("The operator symbol '" . $name . "' is invalid");
}
}
}
