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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.expr.instruct;
import net.sf.saxon.Controller;
import net.sf.saxon.event.Outputter;
import net.sf.saxon.expr.Component;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.expr.XPathContextMajor;
import net.sf.saxon.expr.parser.ExpressionTool;
import net.sf.saxon.expr.parser.RebindingMap;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.StandardNames;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trace.TemplateRuleTraceListener;
import net.sf.saxon.trans.Mode;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.trans.XsltController;
import net.sf.saxon.trans.rules.Rule;
import java.util.Arrays;
/**
* An xsl:next-match element in the stylesheet
*/
public class NextMatch extends ApplyNextMatchingTemplate {
boolean useTailRecursion;
public NextMatch(boolean useTailRecursion) {
super();
this.useTailRecursion = useTailRecursion;
}
/**
* Get the name of this instruction for diagnostic and tracing purposes
*/
@Override
public int getInstructionNameCode() {
return StandardNames.XSL_NEXT_MATCH;
}
/**
* Copy an expression. This makes a deep copy.
*
* @return the copy of the original expression
* @param rebindings the rebinding map
*/
/*@NotNull*/
@Override
public Expression copy(RebindingMap rebindings) {
NextMatch nm2 = new NextMatch(useTailRecursion);
nm2.setActualParams(WithParam.copy(nm2, getActualParams(), rebindings));
nm2.setTunnelParams(WithParam.copy(nm2, getTunnelParams(), rebindings));
ExpressionTool.copyLocationInfo(this, nm2);
return nm2;
}
/*@Nullable*/
@Override
public TailCall processLeavingTail(Outputter output, XPathContext context) throws XPathException {
Controller controller = context.getController();
assert controller != null;
// handle parameters if any
ParameterSet params = assembleParams(context, getActualParams());
ParameterSet tunnels = assembleTunnelParams(context, getTunnelParams());
Rule currentRule = context.getCurrentTemplateRule();
if (currentRule == null) {
XPathException e = new XPathException("There is no current template rule", "XTDE0560");
e.setXPathContext(context);
e.setLocation(getLocation());
throw e;
}
Component.M modeComponent = context.getCurrentMode();
if (modeComponent == null) {
throw new AssertionError("Current mode is null");
}
Mode mode = modeComponent.getActor();
Item currentItem = context.getCurrentIterator().current();
Rule rule = mode.getNextMatchRule(currentItem, currentRule, context);
//Rule rule = controller.getRuleManager().getNextMatchHandler(currentItem, mode.getCode(), currentRule, context);
if (rule == null) { // use the default action for the node
mode.getBuiltInRuleSet().process(currentItem, params, tunnels, output, context, getLocation());
} else if (useTailRecursion) {
// clear all the local variables: they are no longer needed
Arrays.fill(context.getStackFrame().getStackFrameValues(), null);
((XPathContextMajor) context).setCurrentComponent(modeComponent); // bug 2818
return new NextMatchPackage(this, rule, params, tunnels, output, context);
} else {
TemplateRule nh = (TemplateRule) rule.getAction();
nh.initialize();
XPathContextMajor c2 = context.newContext();
c2.setOrigin(this);
//c2.setOriginatingConstructType(LocationKind.TEMPLATE);
c2.openStackFrame(nh.getStackFrameMap());
c2.setLocalParameters(params);
c2.setTunnelParameters(tunnels);
c2.setCurrentTemplateRule(rule);
c2.setCurrentComponent(modeComponent); // needed in the case where next-match is called from a named template
c2.setCurrentMergeGroupIterator(null);
if (mode.isModeTracing()) {
TemplateRuleTraceListener tracer = ((XsltController) controller).getTemplateRuleTraceListener();
tracer.enter("next-match", getLocation(), currentItem, nh);
nh.apply(output, c2);
tracer.leave();
} else {
nh.apply(output, c2);
}
}
return null;
}
/**
* Diagnostic print of expression structure. The abstract expression tree
* is written to the supplied output destination.
*/
@Override
public void export(ExpressionPresenter out) throws XPathException {
out.startElement("nextMatch", this);
String flags = "i";
if (useTailRecursion) {
flags = "t";
}
out.emitAttribute("flags", flags);
if (getActualParams().length != 0) {
WithParam.exportParameters(getActualParams(), out, false);
}
if (getTunnelParams().length != 0) {
WithParam.exportParameters(getTunnelParams(), out, true);
}
out.endElement();
}
/**
* A NextMatchPackage is an object that encapsulates the name of a template to be called,
* the parameters to be supplied, and the execution context. This object can be returned as a tail
* call, so that the actual call is made from a lower point on the stack, allowing a tail-recursive
* template to execute in a finite stack size
*/
private static class NextMatchPackage implements TailCall {
private final NextMatch instruction;
private final Rule rule;
private final ParameterSet params;
private final ParameterSet tunnelParams;
private final Outputter output;
private final XPathContext evaluationContext;
/**
* Construct a NextMatchPackage that contains information about a call.
* @param instruction the xsl:next-match instruction
* @param rule the rule identifying the Template to be called
* @param params the parameters to be supplied to the called template
* @param tunnelParams the tunnel parameter supplied to the called template
* @param evaluationContext saved context information from the Controller (current mode, etc)
* which must be reset to ensure that the template is called with all the context information
* intact
*/
public NextMatchPackage(NextMatch instruction,
Rule rule,
ParameterSet params,
ParameterSet tunnelParams,
Outputter output,
XPathContext evaluationContext) {
this.instruction = instruction;
this.rule = rule;
this.params = params;
this.tunnelParams = tunnelParams;
this.output = output;
this.evaluationContext = evaluationContext;
}
/**
* Process the template call encapsulated by this package.
*
* @return another TailCall. This will never be the original call, but it may be the next
* recursive call. For example, if A calls B which calls C which calls D, then B may return
* a TailCall to A representing the call from B to C; when this is processed, the result may be
* a TailCall representing the call from C to D.
* @throws XPathException if a dynamic error occurs
*/
@Override
public TailCall processLeavingTail() throws XPathException {
TemplateRule nh = (TemplateRule) rule.getAction();
nh.initialize();
XPathContextMajor c2 = evaluationContext.newContext();
c2.setOrigin(instruction);
//c2.setOriginatingConstructType(LocationKind.TEMPLATE);
c2.setLocalParameters(params);
c2.setTunnelParameters(tunnelParams);
c2.openStackFrame(nh.getStackFrameMap());
c2.setCurrentTemplateRule(rule);
c2.setCurrentComponent(evaluationContext.getCurrentComponent());
c2.setCurrentMergeGroupIterator(null);
// System.err.println("Tail call on template");
Mode mode = evaluationContext.getCurrentMode().getActor();
if (mode.isModeTracing()) {
TemplateRuleTraceListener tracer = ((XsltController)evaluationContext.getController()).getTemplateRuleTraceListener();
tracer.enter("next-match", instruction.getLocation(), evaluationContext.getContextItem(), nh);
TailCall tc = nh.applyLeavingTail(output, c2);
tracer.leave();
return tc;
} else {
return nh.applyLeavingTail(output, c2);
}
}
}
/**
* Get the (partial) name of a class that supports streaming of this kind of expression
*
* @return the partial name of a class that can be instantiated to provide streaming support in Saxon-EE,
* or null if there is no such class
*/
@Override
public String getStreamerName() {
return "NextMatch";
}
}