/*
* @(#)$Id: Trace.java 3619 2008-03-26 07:23:03Z yui $
*
* Copyright 2006-2008 Makoto YUI
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Contributors:
* Makoto YUI - initial implementation
*/
package xbird.xquery.func.misc;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import xbird.xquery.XQueryException;
import xbird.xquery.dm.value.Item;
import xbird.xquery.dm.value.Sequence;
import xbird.xquery.dm.value.literal.XString;
import xbird.xquery.dm.value.sequence.ValueSequence;
import xbird.xquery.func.BuiltInFunction;
import xbird.xquery.func.FunctionSignature;
import xbird.xquery.meta.DynamicContext;
import xbird.xquery.type.SequenceType;
import xbird.xquery.type.Type;
import xbird.xquery.type.xs.StringType;
/**
* fn:trace($value as item()*, $label as xs:string) as item()*.
* <DIV lang="en">
* The input $value is returned, unchanged, as the result of the function.
* In addition, the inputs $value, converted to an xs:string, and $label may be directed to
* a trace data set.
* </DIV>
* <DIV lang="ja"></DIV>
*
* @author Makoto YUI (yuin405+xbird@gmail.com)
* @link http://www.w3.org/TR/xquery-operators/#func-trace
*/
public final class Trace extends BuiltInFunction {
private static final long serialVersionUID = 1402147053811134219L;
public static final String SYMBOL = "fn:trace";
public static final Log LOGGER = LogFactory.getLog("TRACE");
public Trace() {
super(SYMBOL, SequenceType.ANY_ITEMS);
}
protected FunctionSignature[] signatures() {
final FunctionSignature[] s = new FunctionSignature[1];
s[0] = new FunctionSignature(getName(), new Type[] { SequenceType.ANY_ITEMS,
StringType.STRING });
return s;
}
public Sequence eval(Sequence<? extends Item> contextSeq, ValueSequence argv, DynamicContext dynEnv)
throws XQueryException {
assert (argv != null && argv.size() == 2);
Item value = argv.getItem(0);
Item secondItem = argv.getItem(1);
XString label = (XString) secondItem;
assert (label != null);
final String message = label.getValue() + ": { " + traceItem(value, ", ") + " }.";
LOGGER.trace(message); // TODO create trace listener?
return value;
}
private static String traceItem(Item items, String delimitter) {
assert (items != null);
final StringBuilder buf = new StringBuilder(256);
boolean first = true;
for(Item it : items) {
if(first) {
first = false;
} else {
buf.append(delimitter);
}
buf.append(it.stringValue());
}
return buf.toString();
}
}