system/classes/Database.php
protected function storeKeyValue($type, $data, $key = false, $comparison = false)
    {
        $dataMember = &$this->$type;
        // If array or object full of data was passed in, add all data
        // to appropriate data member.
        if (is_array($data) || is_object($data)) {
            foreach ($data as $item) {
                array_push($dataMember, $item);
            }
        }

        // Add singular data item to data member.
        else {
            $item = array($key, $comparison, $data);
            array_push($dataMember, $item);
        }
    }
protected function storeKeyValue($type, $data, $key = false, $comparison = false)
    {
        $dataMember = &$this->$type;
        // If array or object full of data was passed in, add all data
        // to appropriate data member.
        if (is_array($data) || is_object($data)) {
            foreach ($data as $item) {
                array_push($dataMember, $item);
            }
        }

        // Add singular data item to data member.
        else {
            $item = array($key, $comparison, $data);
            array_push($dataMember, $item);
        }
    }
For storing an array of data that represents an item.
STORAGE FORMAT:
[
[column, operator, value],
[name, LIKE, %s],
[price, >, 100]
]