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The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2022 Saxonica Limited
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.functions;
import net.sf.saxon.Controller;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.expr.parser.Loc;
import net.sf.saxon.s9api.Location;
import net.sf.saxon.lib.Logger;
import net.sf.saxon.lib.TraceListener;
import net.sf.saxon.ma.arrays.ArrayItem;
import net.sf.saxon.ma.map.MapItem;
import net.sf.saxon.om.*;
import net.sf.saxon.str.StringView;
import net.sf.saxon.trace.Traceable;
import net.sf.saxon.trans.Err;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.util.Navigator;
import net.sf.saxon.type.Type;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.ObjectValue;
import java.util.HashMap;
import java.util.Map;
/**
* This class supports the XPath 2.0 function trace().
* The value is traced to the registered output stream (defaulting to System.err),
* unless a TraceListener is in use, in which case the information is sent to the TraceListener
*/
public class Trace extends SystemFunction implements Traceable {
Location location = Loc.NONE;
/**
* Get the static properties of this expression (other than its type). The result is
* bit-significant. These properties are used for optimizations. In general, if
* property bit is set, it is true, but if it is unset, the value is unknown.
* @param arguments the actual arguments
*/
@Override
public int getSpecialProperties(Expression[] arguments) {
return arguments[0].getSpecialProperties();
}
@Override
public int getCardinality(Expression[] arguments) {
return arguments[0].getCardinality();
}
public void notifyListener(String label, Sequence val, XPathContext context) {
Map info = new HashMap<>();
info.put("label", label);
info.put("value", val);
TraceListener listener = context.getController().getTraceListener();
listener.enter(this, info, context);
listener.leave(this);
}
@Override
public Expression makeFunctionCall(Expression... arguments) {
// Fix bug 2597
Expression e = super.makeFunctionCall(arguments);
location = e.getLocation();
return e;
}
public static void traceItem(/*@Nullable*/ Item val, String label, Logger out) {
if (val == null) {
out.info(label);
} else {
if (val instanceof NodeInfo) {
out.info(label + ": " + Type.displayTypeName(val) + ": "
+ Navigator.getPath((NodeInfo) val));
} else if (val instanceof AtomicValue) {
out.info(label + ": " + Type.displayTypeName(val) + ": "
+ val.getUnicodeStringValue());
} else if (val instanceof ArrayItem || val instanceof MapItem) {
out.info(label + ": " + val.toShortString());
} else if (val instanceof Function) {
StructuredQName name = ((Function)val).getFunctionName();
out.info(label + ": function " + (name==null ? "(anon)" : name.getDisplayName()) + "#" + ((Function)val).getArity());
} else if (val.getGenre() == Genre.EXTERNAL) {
Object obj = ((ObjectValue)val).getObject();
out.info(label + ": " + obj.getClass().getName() + " = " + Err.truncate30(StringView.tidy(obj.toString())));
} else {
out.info(label + ": " + val.toShortString());
}
}
}
@Override
public Location getLocation() {
return location;
}
/**
* Evaluate the expression
*
* @param context the dynamic evaluation context
* @param arguments the values of the arguments, supplied as SequenceIterators
* @return the result of the evaluation, in the form of a SequenceIterator
* @throws net.sf.saxon.trans.XPathException
* if a dynamic error occurs during the evaluation of the expression
*/
@Override
public Sequence call(XPathContext context, Sequence[] arguments) throws XPathException {
Controller controller = context.getController();
String label = arguments.length == 1 ? "*" : arguments[1].head().getStringValue();
if (controller.isTracing()) {
Sequence value = SequenceTool.toGroundedValue(arguments[0].iterate());
notifyListener(label, value, context);
return value;
} else {
Logger out = controller.getTraceFunctionDestination();
if (out == null) {
return arguments[0];
} else {
return SequenceTool.toLazySequence(new TracingIterator(arguments[0].iterate(),
label, out));
}
}
}
/**
* Get a name identifying the object of the expression, for example a function name, template name,
* variable name, key name, element name, etc. This is used only where the name is known statically.
*
* @return the QName of the object declared or manipulated by this instruction or expression
*/
@Override
public StructuredQName getObjectName() {
return null;
}
/**
* Tracing Iterator class
*/
private class TracingIterator implements SequenceIterator {
private final SequenceIterator base;
private final String label;
private final Logger out;
private boolean empty = true;
private int position = 0;
public TracingIterator(SequenceIterator base, String label, Logger out) {
this.base = base;
this.label = label;
this.out = out;
}
@Override
public Item next() {
Item n = base.next();
position++;
if (n == null) {
if (empty) {
traceItem(null, label + ": empty sequence", out);
}
} else {
traceItem(n, label + " [" + position + ']', out);
empty = false;
}
return n;
}
@Override
public void close() {
base.close();
}
@Override
public void discharge() {
base.discharge();
}
}
@Override
public String getStreamerName() {
return "Trace";
}
}