/** * Do code generation for this conversion of a value from the Java to the SQL domain. * * @param acb The ExpressionClassBuilder for the class we're generating * @param mb the method the expression will go into * @exception StandardException Thrown on error */ public void generateExpression(ExpressionClassBuilder acb, MethodBuilder mb) throws StandardException { TypeId resultType; String resultTypeName; /* ** Tell the Java node that it's value is being returned to the ** SQL domain. This way, it knows whether the checking for a null ** receiver is to be done at the Java level or the SQL level. */ javaNode.returnValueToSQLDomain(); /* Generate the receiver, if any. */ boolean hasReceiver = javaNode.generateReceiver(acb, mb); /* ** If the java expression has a receiver, we want to check whether ** it's null before evaluating the whole expression (to avoid ** a NullPointerException. */ if (hasReceiver) { /* ** There is a receiver. Generate a null SQL value to return ** in case the receiver is null. First, create a field to hold ** the null SQL value. */ String nullValueClass = getTypeCompiler().interfaceName(); LocalField nullValueField = acb.newFieldDeclaration(Modifier.PRIVATE, nullValueClass); /* ** There is a receiver. Generate the following to test ** for null: ** ** (receiverExpression == null) ? */ mb.conditionalIfNull(); mb.getField(nullValueField); acb.generateNullWithExpress(mb, getTypeCompiler(), getTypeServices().getCollationType()); /* ** We have now generated the expression to test, and the ** "true" side of the ?: operator. Finish the "true" side ** so we can generate the "false" side. */ mb.startElseCode(); } resultType = getTypeId(); TypeCompiler tc = getTypeCompiler(); resultTypeName = tc.interfaceName(); /* Allocate an object for re-use to hold the result of the conversion */ LocalField field = acb.newFieldDeclaration(Modifier.PRIVATE, resultTypeName); /* Generate the expression for the Java value under us */ javaNode.generateExpression(acb, mb); /* Generate the SQL value, which is always nullable */ acb.generateDataValue(mb, tc, getTypeServices().getCollationType(), field); /* ** If there was a receiver, the return value will be the result ** of the ?: operator. */ if (hasReceiver) { mb.completeConditional(); } }