class StringBasedFileContent

class StringBasedFileContent extends SeekableFileContent implements FileContent {
    
    /**
     * actual content
     *
     * @type  string
     */
    private $content;
    
    /**
     * constructor
     *
     * @param  string  $content
     */
    public function __construct($content) {
        $this->content = $content;
    }
    
    /**
     * returns actual content
     *
     * @return  string
     */
    public function content() {
        return $this->content;
    }
    
    /**
     * returns size of content
     *
     * @return  int
     */
    public function size() {
        return strlen($this->content);
    }
    
    /**
     * actual reading of length starting at given offset
     *
     * @param  int  $offset
     * @param  int  $count
     */
    protected function doRead($offset, $count) {
        return (string) substr($this->content, $offset, $count);
    }
    
    /**
     * actual writing of data with specified length at given offset
     *
     * @param   string  $data
     * @param   int     $offset
     * @param   int     $length
     */
    protected function doWrite($data, $offset, $length) {
        $this->content = substr($this->content, 0, $offset) . $data . substr($this->content, $offset + $length);
    }
    
    /**
     * Truncates a file to a given length
     *
     * @param   int  $size length to truncate file to
     * @return  bool
     */
    public function truncate($size) {
        if ($size > $this->size()) {
            // Pad with null-chars if we're "truncating up"
            $this->content .= str_repeat("\x00", $size - $this->size());
        }
        else {
            $this->content = substr($this->content, 0, $size);
        }
        return true;
    }

}