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From Eldon Carman <ecarm...@ucr.edu>
Subject Re: Arithmetic Functions
Date Fri, 15 Jun 2012 22:11:41 GMT
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 <vborky@yahoo.com> 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

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