public AbstractExpression getFirstArgument ( ) { if ( m_left != null ) { assert ( m_args == null ) ; return m_left ; } if ( m_args != null && m_args . size ( ) > 0 ) { assert ( m_left == null && m_right == null ) ; return m_args . get ( 0 ) ; } return null ; }
Ferret out the first argument . This can be m_left or else the first element of m_args .