Truncate at space, Zend View Helper

When writing web applications you may frequently find the need to truncate strings. In php you could just use substr but that could be dangerous.

Therefore the safest idea is to truncate back to the nearest space. The code below is a Zend View Helper, constructed in a way to read cleanly in the page. It’s use in a Zend View is as follows:

<?$string = 'Hello People';?>
<?=$this->truncate($string)->toLength(10)?>
<?=$this->truncate($string)->toLength(10)->withPostfix('--')?>
<?=$this->truncate($string)->midword()->toLength(10)->withPostfix('--')?>

As each method returns itself they can be chained together. The above outputs;

Hello…
Hello--
Hello peop--

Methods

<?php
class Zend_View_Helper_Truncate extends Zend_View_Helper_Abstract {
        private $_string;
        private $_length;
        private $_postfix;
        private $_cutatspace = true;

        public function truncate($string) {
            $this->_string = trim($string);
            $this->_defaultValues();
            return $this;
        }

        private function _defaultValues() {
            $this->toLength(100);
            $this->withPostfix('&#0133;');
         }

        public function midword() {
            $this->_cutatspace = false;
            return $this;
        }

        public function toLength($int) {
            $this->_length = (int) $int;
            return $this;
        }
        public function withPostfix($str) {
            $this->_postfix = $str;
            return $this;
        }

        public function render() {
            // Return empty string if max length < 1
            if ($this->_length < 1) {
                return '';
            }

            // Return full string if max length >= string length
            if ($this->_length >= strlen($this->_string)) {
                return $this->_string;
            }

            // Return truncated string
            if ($this->_cutatspace) {
                while (strlen($this->_string) > $this->_length) {
                    $cutPos = strrpos($this->_string, ' ', -1);
                    if ($cutPos === false) {
                        // no spaces left, whole string truncated
                        return '';
                    }
                    $this->_string = trim(substr($this->_string, 0, $cutPos));
                }
            } else {
                $this->_string = trim(substr($this->_string, 0, $this->_length));
            }
            return $this->_string . $this->_postfix;
        }

        public function __toString() {
            return $this->render();
        }
}

Update 11/02/2012: Steve noted an issue with this helper. I have updated the code above based on his suggestion. Thanks Steve.