public Operator operator ( String fldName ) { if ( lhs . isFieldName ( ) && lhs . asFieldName ( ) . equals ( fldName ) ) return op ; if ( rhs . isFieldName ( ) && rhs . asFieldName ( ) . equals ( fldName ) ) return op . complement ( ) ; return null ; }
Determines if this term is of the form F&lt ; OP&gt ; E where F is the specified field &lt ; OP&gt ; is an operator and E is an expression . If so the method returns &lt ; OP&gt ; . If not the method returns null .