function __construct($head, array $body)
{
if (!$head instanceof Term) {
throw new LogicException('Chain::__construct() : head is not Term type.');
}
$bodylist = new FList($body);
$_bodylist = $bodylist->filter(function ($item) {
if ($item instanceof Term) {
return TRUE;
} else {
return FALSE;
}
});
if ($_bodylist->length() < 1) {
throw new LogicException('Chain::__construct() : no body defined.');
}
$letters = up_letter_gen();
// [A-Z] : generator
$head->addVariable($this->checkVariableByName($letters->current()));
$pre = NULL;
$this->body = $_bodylist->map(function ($item) use($letters, &$pre) {
// link body terms.
if (isset($pre)) {
$pre->setNext($item);
}
$pre = $item;
// set variables
$item->addVariable($this->checkVariableByName($letters->current()));
$letters->next();
$item->addVariable($this->checkVariableByName($letters->current()));
return $item;
});
$head->addVariable($this->checkVariableByName($letters->current()));
$this->head = $head;
}
