src/Zend/Filter/PregReplace.php
public function filter($value)
    {
        if ($this->_matchPattern == null) {

            throw new Zend_Filter_Exception(get_class($this) . ' does not have a valid MatchPattern set.');
        }

        return preg_replace($this->_matchPattern, $this->_replacement, $value);
    }
public function filter($value)
    {
        if ($this->_matchPattern == null) {

            throw new Zend_Filter_Exception(get_class($this) . ' does not have a valid MatchPattern set.');
        }

        return preg_replace($this->_matchPattern, $this->_replacement, $value);
    }
Perform regexp replacement as filter

@param  string $value
@return string