question: 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 "" ; } }
target:  Evaluate the AVT and return a String.