original_string: public function setEncoding($encoding)
      {
          if (empty($encoding))
              throw new \InvalidArgumentException('The encoding may not be empty or NULL.');
          if (!is_string($encoding))
              throw new \InvalidArgumentException('The encoding must be a string.');
  
          $this->encoding = $encoding;
  
          return $this;
      }
code: public function setEncoding($encoding)
      {
          if (empty($encoding))
              throw new \InvalidArgumentException('The encoding may not be empty or NULL.');
          if (!is_string($encoding))
              throw new \InvalidArgumentException('The encoding must be a string.');
  
          $this->encoding = $encoding;
  
          return $this;
      }
code_tokens: public function setEncoding ( $ encoding ) { if ( empty ( $ encoding ) ) throw new \ InvalidArgumentException ( 'The encoding may not be empty or NULL.' ) ; if ( ! is_string ( $ encoding ) ) throw new \ InvalidArgumentException ( 'The encoding must be a string.' ) ; $ this -> encoding = $ encoding ; return $ this ; }
docstring: Set the 'encoding' attribute in the XML prolog.
  
  @access   public
  @param    string $encoding value of 'encoding' attribute
  @return   self
  @throws   \InvalidArgumentException if the encoding is not a string, empty or NULL.
docstring_tokens: Set the encoding attribute in the XML prolog .