/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-06 Wolfgang M. Meier
* wolfgang@exist-db.org
* http://exist.sourceforge.net
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
*/
package org.exist.xquery.functions;
import java.text.Collator;
import org.exist.dom.QName;
import org.exist.util.Collations;
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.AtomicValue;
import org.exist.xquery.value.ComputableValue;
import org.exist.xquery.value.DoubleValue;
import org.exist.xquery.value.FloatValue;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.NumericValue;
import org.exist.xquery.value.QNameValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceIterator;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;
/**
* @author Wolfgang Meier (wolfgang@exist-db.org)
*/
public class FunMax extends CollatingFunction {
protected static final String FUNCTION_DESCRIPTION_COMMON_1 =
"Selects an item from the input sequence $arg whose value is " +
"greater than or equal to the value of every other item in the " +
"input sequence. If there are two or more such items, then the " +
"specific item whose value is returned is implementation dependent.\n\n" +
"The following rules are applied to the input sequence:\n\n" +
"- Values of type xs:untypedAtomic in $arg are cast to xs:double.\n" +
"- Numeric and xs:anyURI values are converted to the least common " +
"type that supports the 'ge' operator by a combination of type " +
"promotion and subtype substitution. See Section B.1 Type " +
"PromotionXP and Section B.2 Operator MappingXP.\n\n" +
"The items in the resulting sequence may be reordered in an arbitrary " +
"order. The resulting sequence is referred to below as the converted " +
"sequence. This function returns an item from the converted sequence " +
"rather than the input sequence.\n\n" +
"If the converted sequence is empty, the empty sequence is returned.\n\n" +
"All items in $arg must be numeric or derived from a single base type " +
"for which the 'ge' operator is defined. In addition, the values in the " +
"sequence must have a total order. If date/time values do not have a " +
"timezone, they are considered to have the implicit timezone provided " +
"by the dynamic context for purposes of comparison. Duration values " +
"must either all be xs:yearMonthDuration values or must all be " +
"xs:dayTimeDuration values.\n\n" +
"If any of these conditions is not met, then a type error is raised [err:FORG0006].\n\n" +
"If the converted sequence contains the value NaN, the value NaN is returned.\n\n" +
"If the items in the value of $arg are of type xs:string or types " +
"derived by restriction from xs:string, then the determination of " +
"the item with the largest value is made according to the collation " +
"that is used.";
protected static final String FUNCTION_DESCRIPTION_2_PARAM =
"If the type of the items in $arg is not xs:string " +
"and $collation-uri is specified, the collation is ignored.\n\n";
protected static final String FUNCTION_DESCRIPTION_COMMON_2 =
"The collation used by the invocation of this function is " +
"determined according to the rules in 7.3.1 Collations.";
public final static FunctionSignature signatures[] = {
new FunctionSignature(
new QName("max", Function.BUILTIN_FUNCTION_NS),
FUNCTION_DESCRIPTION_COMMON_1 +
FUNCTION_DESCRIPTION_COMMON_2,
new SequenceType[] {
new FunctionParameterSequenceType("arg", Type.ATOMIC, Cardinality.ZERO_OR_MORE, "The input sequence")
},
new FunctionReturnSequenceType(Type.ATOMIC, Cardinality.ZERO_OR_ONE, "the max value")
),
new FunctionSignature(
new QName("max", Function.BUILTIN_FUNCTION_NS),
FUNCTION_DESCRIPTION_COMMON_1 + FUNCTION_DESCRIPTION_2_PARAM +
FUNCTION_DESCRIPTION_COMMON_2,
new SequenceType[] {
new FunctionParameterSequenceType("arg", Type.ATOMIC, Cardinality.ZERO_OR_MORE, "The input sequence"),
new FunctionParameterSequenceType("collation-uri", Type.STRING, Cardinality.EXACTLY_ONE, "The collation URI")
},
new FunctionReturnSequenceType(Type.ATOMIC, Cardinality.ZERO_OR_ONE, "the max value")
)
};
/**
* @param context
* @param signature
*/
public FunMax(XQueryContext context, FunctionSignature signature) {
super(context, signature);
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#eval(org.exist.dom.DocumentSet, org.exist.xquery.value.Sequence, org.exist.xquery.value.Item)
*/
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;
Sequence arg = getArgument(0).eval(contextSequence, contextItem);
if(arg.isEmpty())
result = Sequence.EMPTY_SEQUENCE;
else {
boolean computableProcessing = false;
//TODO : test if a range index is defined *iff* it is compatible with the collator
Collator collator = getCollator(contextSequence, contextItem, 2);
SequenceIterator iter = arg.unorderedIterator();
AtomicValue max = null;
while (iter.hasNext()) {
Item item = iter.nextItem();
if (item instanceof QNameValue)
throw new XPathException(this, "FORG0006: Cannot compare " + Type.getTypeName(item.getType()));
AtomicValue value = item.atomize();
//Any value of type xdt:untypedAtomic is cast to xs:double
if (value.getType() == Type.UNTYPED_ATOMIC)
value = value.convertTo(Type.DOUBLE);
if (max == null)
max = value;
else {
if (Type.getCommonSuperType(max.getType(), value.getType()) == Type.ATOMIC) {
throw new XPathException(this, "FORG0006: Cannot compare " + Type.getTypeName(max.getType()) +
" and " + Type.getTypeName(value.getType()));
}
//Any value of type xdt:untypedAtomic is cast to xs:double
if (value.getType() == Type.UNTYPED_ATOMIC)
value = value.convertTo(Type.DOUBLE);
//Numeric tests
if (Type.subTypeOf(value.getType(), Type.NUMBER)) {
//Don't mix comparisons
if (!Type.subTypeOf(max.getType(), Type.NUMBER))
throw new XPathException(this, "FORG0006: Cannot compare " + Type.getTypeName(max.getType()) +
" and " + Type.getTypeName(value.getType()));
if (((NumericValue) value).isNaN()) {
//Type NaN correctly
value = value.promote(max);
if (value.getType() == Type.FLOAT)
max = FloatValue.NaN;
else
max = DoubleValue.NaN;
//although result will be NaN, we need to continue on order to type correctly
continue;
} else
max = max.promote(value);
}
//Ugly test
if (max instanceof ComputableValue && value instanceof ComputableValue) {
//Type value correctly
value = value.promote(max);
max = (ComputableValue) max.max(collator, value);
computableProcessing = true;
} else {
if (computableProcessing)
throw new XPathException(this, "FORG0006: Cannot compare " + Type.getTypeName(max.getType()) +
" and " + Type.getTypeName(value.getType()));
if (Collations.compare(collator, value.getStringValue(), max.getStringValue()) > 0)
max = value;
}
}
}
result = max;
}
if (context.getProfiler().isEnabled())
context.getProfiler().end(this, "", result);
return result;
}
}