Lexicographical order is text sort order. So: decimal double float integer
xs:integer is supposed to be infinite precision, but we represent it as a 64 bit fixed-precision signed-integer which is a long in java.
Vinayak On 6/15/12 3:11 PM, Eldon Carman wrote:
Thanks for the scaffolding. I have two questions. Is this the correct lexicographical order? 1. double 2. float 3. decimal 4. integer Also do we always referrer to a integer as a long for this implementation? Preston On Fri, Jun 15, 2012 at 7:09 AM, Vinayak Borkar<[email protected]> wrote:Preston, I have now added some scaffolding so that implementing the arithmetic functions will be easier. I have also added the code for xs:integer + xs:integer which is needed for the 1 + 1 example, ant it works end-to-end. Look at the AddScalarEvaluatorFactory class. You will be creating a class like that for each of Subtract, Multiply, and Divide by extending AbstractArithmeticScalarEvaluatorFactory. The only method that you have to implement when you extend AbstractArithmeticScalarEvaluatorFactory is the createArithmeticOperation() method that creates an instance of AbstractArithmeticOperation. For example, the one for Add looks like this: @Override protected AbstractArithmeticOperation createArithmeticOperation() { return new AddOperation(); } The AddOperation implements all the logic for what it means to add two values of various types. The AbstractArithmeticScalarEvaluatorFactory has all the logic to correctly dispatch to the correct method in AbstractArithmeticOperation based on XQuery rules. As your next step, please implement all the methods in AddOperation. The methods in this class look like void operateXY(X x, Y y, DataOutput dOut) where X and Y are type names. For example the method that computes the result for xs:integer and xs:double would read: void operateIntegerDouble(LongPointable longp, DoublePointable doublep, DataOutput dOut) Since Add is commutative, you can implement about half of the methods by delegating to the other half (by switching the arguments). The convention you should follow is have operateXY delegate to operateYX when X is lexicographically greater than Y. So in the above example, operateIntegerDouble will delegate to operateDoubleInteger in the AddOperation class. Note that this trick does not apply to Minus and Divide, but applied to Multiply. Let us know how it goes with implementing the unimplemented methods in AddOperation and then implemnting the other arithmetic operation classes. Vinayak
