net.sf.saxon.trace.ContextStackIterator Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of Saxon-HE Show documentation
Show all versions of Saxon-HE Show documentation
The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2023 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.trace;
import net.sf.saxon.Controller;
import net.sf.saxon.expr.ContextOriginator;
import net.sf.saxon.expr.UserFunctionCall;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.expr.XPathContextMajor;
import net.sf.saxon.expr.instruct.*;
import net.sf.saxon.trans.rules.BuiltInRuleSet;
import java.util.Iterator;
/**
* This class provides a representation of the current runtime call stack, as represented by the stack
* of XPathContext objects.
*/
public class ContextStackIterator implements Iterator {
// TODO: this class is no longer used by StandardErrorListener.printStackTrace(). It's potentially
// still useful to have a programmatic way of obtaining the stack trace, but this class is rather
// clumsy and probably isn't used.
private XPathContextMajor nextFrame;
/**
* Create an iterator over the stack of XPath dynamic context objects, starting with the top-most
* stackframe and working down. The objects returned by this iterator will be of class {@link ContextStackFrame}.
* Note that only "major" context objects are considered - those that have a stack frame of their own.
*
* @param context the current context
*/
public ContextStackIterator(XPathContext context) {
if (!(context instanceof XPathContextMajor)) {
context = getMajorCaller(context);
}
nextFrame = (XPathContextMajor) context;
}
/**
* Returns true if the iteration has more elements. (In other
* words, returns true if next would return an element
* rather than throwing an exception.)
*
* @return true if the iterator has more elements.
*/
@Override
public boolean hasNext() {
return nextFrame != null;
}
/**
* Returns the next element in the iteration. Calling this method
* repeatedly until the {@link #hasNext()} method returns false will
* return each element in the underlying collection exactly once.
*
* @return the next element in the iteration, which will always be an instance
* of {@link ContextStackFrame}
* @throws java.util.NoSuchElementException
* iteration has no more elements.
*/
/*@Nullable*/
@Override
public ContextStackFrame next() {
XPathContextMajor context = nextFrame;
if (context == null) {
return null;
}
ContextOriginator origin = context.getOrigin();
if (origin instanceof Controller) {
nextFrame = getMajorCaller(context);
return new ContextStackFrame.CallingApplication();
} else if (origin instanceof BuiltInRuleSet) {
nextFrame = getMajorCaller(context);
return new ContextStackFrame.BuiltInTemplateRule(context);
} else if (origin instanceof UserFunction) {
ContextStackFrame.FunctionCall sf = new ContextStackFrame.FunctionCall();
UserFunction ufc = (UserFunction) origin;
sf.setLocation(ufc.getLocation());
sf.setFunctionName(ufc.getFunctionName());
sf.setContextItem(context.getContextItem());
sf.setContext(context);
nextFrame = getMajorCaller(context);
return sf;
} else if (origin instanceof UserFunctionCall) {
// No longer used? Bug 3671
ContextStackFrame.FunctionCall sf = new ContextStackFrame.FunctionCall();
UserFunctionCall ufc = (UserFunctionCall) origin;
sf.setLocation(ufc.getLocation());
sf.setFunctionName(ufc.getFunctionName());
sf.setContextItem(context.getContextItem());
sf.setContext(context);
nextFrame = getMajorCaller(context);
return sf;
} else if (origin instanceof ApplyTemplates) {
ContextStackFrame.ApplyTemplates sf = new ContextStackFrame.ApplyTemplates();
ApplyTemplates loc = (ApplyTemplates) origin;
sf.setLocation(loc.getLocation());
sf.setContextItem(context.getContextItem());
sf.setContext(context);
nextFrame = getMajorCaller(context);
return sf;
} else if (origin instanceof CallTemplate) {
ContextStackFrame.CallTemplate sf = new ContextStackFrame.CallTemplate();
CallTemplate loc = (CallTemplate) origin;
sf.setLocation(loc.getLocation());
sf.setTemplateName(loc.getObjectName());
sf.setContextItem(context.getContextItem());
sf.setContext(context);
nextFrame = getMajorCaller(context);
return sf;
} else if (origin instanceof GlobalVariable) {
ContextStackFrame.VariableEvaluation sf = new ContextStackFrame.VariableEvaluation();
GlobalVariable var = (GlobalVariable) origin;
sf.setLocation(var.getLocation());
sf.setContextItem(context.getContextItem());
sf.setVariableName(var.getVariableQName());
sf.setComponent(var);
sf.setContext(context);
nextFrame = getMajorCaller(context);
return sf;
} else {
//other context changes are not considered significant enough to report
//out.println(" In unidentified location " + construct);
nextFrame = getMajorCaller(context);
ContextStackFrame csf = next();
if (csf == null) {
// we can't return null, because hasNext() returned true...
return new ContextStackFrame.CallingApplication();
} else {
return csf;
}
}
}
private static XPathContextMajor getMajorCaller(XPathContext context) {
XPathContext caller = context.getCaller();
return caller.getMajorContext();
}
/**
* Removes from the underlying collection the last element returned by the
* iterator (optional operation).
*
* @throws UnsupportedOperationException as the remove
* operation is not supported by this Iterator.
*/
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}