/*
* eXist Open Source Native XML Database
* Copyright (C) 2005-2009 The eXist Project
* http://exist-db.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $Id$
*/
package org.exist.xquery.functions.fn;
import org.exist.dom.QName;
import org.exist.xquery.Cardinality;
import org.exist.xquery.Dependency;
import org.exist.xquery.Function;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.Profiler;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.IntegerValue;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.NumericValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;
/**
* Implements the fn:roud-half-to-even() function.
*
* @author wolf
*
*/
public class FunRoundHalfToEven extends Function {
protected static final String FUNCTION_DESCRIPTION_1_PARAM =
"The value returned is the nearest (that is, numerically closest) " +
"value to $arg that is a multiple of ten to the power of minus 0. ";
protected static final String FUNCTION_DESCRIPTION_2_PARAM =
"The value returned is the nearest (that is, numerically closest) " +
"value to $arg that is a multiple of ten to the power of minus " +
"$precision. ";
protected static final String FUNCTION_DESCRIPTION_COMMON =
"If two such values are equally near (e.g. if the " +
"fractional part in $arg is exactly .500...), the function returns " +
"the one whose least significant digit is even.\n\nIf the type of " +
"$arg is one of the four numeric types xs:float, xs:double, " +
"xs:decimal or xs:integer the type of the result is the same as " +
"the type of $arg. If the type of $arg is a type derived from one " +
"of the numeric types, the result is an instance of the " +
"base numeric type.\n\n" +
"The three argument version of the function with $precision = 0 " +
"produces the same result as the two argument version.\n\n" +
"For arguments of type xs:float and xs:double, if the argument is " +
"NaN, positive or negative zero, or positive or negative infinity, " +
"then the result is the same as the argument. In all other cases, " +
"the argument is cast to xs:decimal, the function is applied to this " +
"xs:decimal value, and the resulting xs:decimal is cast back to " +
"xs:float or xs:double as appropriate to form the function result. " +
"If the resulting xs:decimal value is zero, then positive or negative " +
"zero is returned according to the sign of the original argument.\n\n" +
"Note that the process of casting to xs:decimal " +
"may result in an error [err:FOCA0001].\n\n" +
"If $arg is of type xs:float or xs:double, rounding occurs on the " +
"value of the mantissa computed with exponent = 0.";
protected static final FunctionParameterSequenceType ARG_PARAM = new FunctionParameterSequenceType("arg", Type.NUMBER, Cardinality.ZERO_OR_ONE, "The input number");
protected static final FunctionParameterSequenceType PRECISION_PARAM = new FunctionParameterSequenceType("precision", Type.NUMBER, Cardinality.ZERO_OR_ONE, "The precision factor");
protected static final FunctionReturnSequenceType RETURN_TYPE = new FunctionReturnSequenceType(Type.NUMBER, Cardinality.EXACTLY_ONE, "the rounded value");
public final static FunctionSignature signatures[] = {
new FunctionSignature(
new QName("round-half-to-even", Function.BUILTIN_FUNCTION_NS),
FUNCTION_DESCRIPTION_1_PARAM + FUNCTION_DESCRIPTION_COMMON,
new SequenceType[] { ARG_PARAM },
RETURN_TYPE),
new FunctionSignature(new QName("round-half-to-even",
Function.BUILTIN_FUNCTION_NS),
FUNCTION_DESCRIPTION_2_PARAM + FUNCTION_DESCRIPTION_COMMON,
new SequenceType[] { ARG_PARAM, PRECISION_PARAM },
RETURN_TYPE )
};
public FunRoundHalfToEven(XQueryContext context,
FunctionSignature signatures) {
super(context, signatures);
}
public int returnsType() {
return Type.DOUBLE;
}
public Sequence eval(Sequence contextSequence, Item contextItem) throws XPathException {
if (context.getProfiler().isEnabled()) {
context.getProfiler().start(this);
context.getProfiler().message(this, Profiler.DEPENDENCIES, "DEPENDENCIES", Dependency.getDependenciesName(this.getDependencies()));
if (contextSequence != null)
{context.getProfiler().message(this, Profiler.START_SEQUENCES, "CONTEXT SEQUENCE", contextSequence);}
if (contextItem != null)
{context.getProfiler().message(this, Profiler.START_SEQUENCES, "CONTEXT ITEM", contextItem.toSequence());}
}
Sequence result;
IntegerValue precision = null;
final Sequence seq = getArgument(0).eval(contextSequence, contextItem);
if (seq.isEmpty())
{result = Sequence.EMPTY_SEQUENCE;}
else {
if (contextItem != null)
{contextSequence = contextItem.toSequence();}
if (getSignature().getArgumentCount() > 1) {
precision = (IntegerValue) getArgument(1).eval(contextSequence, contextItem).itemAt(0).convertTo(Type.INTEGER);
}
final Item item = seq.itemAt(0);
NumericValue value;
if (item instanceof NumericValue) {
value = (NumericValue) item;
} else {
value = (NumericValue) item.convertTo(Type.NUMBER);
}
result = value.round(precision);
}
if (context.getProfiler().isEnabled())
{context.getProfiler().end(this, "", result);}
return result;
}
}