code: public String evaluate(
            XPathContext xctxt, int context, org.apache.xml.utils.PrefixResolver nsNode)
              throws javax.xml.transform.TransformerException
    {
      if (null != m_simpleString){
          return m_simpleString;
      }else if (null != m_parts){
        final FastStringBuffer buf =getBuffer();
        String out = null;
        int n = m_parts.size();
        try{
          for (int i = 0; i < n; i++){
            AVTPart part = (AVTPart) m_parts.elementAt(i);  
            part.evaluate(xctxt, buf, context, nsNode);
          }
         out = buf.toString();
        }finally{
            if(USE_OBJECT_POOL){
               StringBufferPool.free(buf);
           }else{
             buf.setLength(0); 
           }
        }
       return out;
      }else{
        return "";
      }
    }
docs: Evaluate the AVT and return a String.
  
  @param xctxt Te XPathContext to use to evaluate this.
  @param context The current source tree context.
  @param nsNode The current namespace context (stylesheet tree context).
  
  @return The AVT evaluated as a string
  
  @throws javax.xml.transform.TransformerException