/*
* @(#)RoundFunction.java
*
* Copyright 2003-2004 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistribution of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistribution in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
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*
* Neither the name of Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
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package com.sun.xacml.cond;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import com.sun.xacml.EvaluationCtx;
import com.sun.xacml.attr.AttributeValue;
import com.sun.xacml.attr.DoubleAttribute;
/**
* A class that implements the round function. It takes one double operand, rounds that value to an
* integer and returns that integer. If the operand is indeterminate, an indeterminate result is
* returned.
*
* @since 1.0
* @author Steve Hanna
* @author Seth Proctor
*
* Adding generic type support by Christian Mueller (geotools)
*/
public class RoundFunction extends FunctionBase {
/**
* Standard identifier for the round function.
*/
public static final String NAME_ROUND = FUNCTION_NS + "round";
/**
* Creates a new <code>RoundFunction</code> object.
*
* @param functionName
* the standard XACML name of the function to be handled by this object, including
* the full namespace
*
* @throws IllegalArgumentException
* if the function is unknown
*/
public RoundFunction(String functionName) {
super(NAME_ROUND, 0, DoubleAttribute.identifier, false, 1, DoubleAttribute.identifier,
false);
if (!functionName.equals(NAME_ROUND))
throw new IllegalArgumentException("unknown round function: " + functionName);
}
/**
* Returns a <code>Set</code> containing all the function identifiers supported by this class.
*
* @return a <code>Set</code> of <code>String</code>s
*/
public static Set<String> getSupportedIdentifiers() {
Set<String> set = new HashSet<String>();
set.add(NAME_ROUND);
return set;
}
/**
* Evaluate the function, using the specified parameters.
*
* @param inputs
* a <code>List</code> of <code>Evaluatable</code> objects representing the arguments
* passed to the function
* @param context
* an <code>EvaluationCtx</code> so that the <code>Evaluatable</code> objects can be
* evaluated
* @return an <code>EvaluationResult</code> representing the function's result
*/
public EvaluationResult evaluate(List<? extends Expression> inputs, EvaluationCtx context) {
// Evaluate the arguments
AttributeValue[] argValues = new AttributeValue[inputs.size()];
EvaluationResult result = evalArgs(inputs, context, argValues);
if (result != null)
return result;
// Now that we have real values, perform the round operation
double arg = ((DoubleAttribute) argValues[0]).getValue();
double roundValue = Math.round(arg);
// Make it round half even, not round nearest
double lower = Math.floor(arg);
double higher = lower + 1;
if ((arg - lower) == (higher - arg)) {
if ((lower % 2) == 0)
roundValue = lower;
else
roundValue = higher;
}
return new EvaluationResult(new DoubleAttribute(roundValue));
}
}