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The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2015 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.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.om.Item;
import net.sf.saxon.om.StandardNames;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trans.Mode;
import net.sf.saxon.trans.Rule;
import net.sf.saxon.trans.XPathException;
import java.util.Arrays;
/**
* An xsl:next-match element in the stylesheet
*/
public class NextMatch extends ApplyImports {
boolean useTailRecursion;
public NextMatch(boolean useTailRecursion) {
super();
this.useTailRecursion = useTailRecursion;
}
/**
* Get the name of this instruction for diagnostic and tracing purposes
*/
public int getInstructionNameCode() {
return StandardNames.XSL_NEXT_MATCH;
}
/**
* Copy an expression. This makes a deep copy.
*
* @return the copy of the original expression
*/
/*@NotNull*/
public Expression copy() {
NextMatch nm2 = new NextMatch(useTailRecursion);
nm2.setActualParams(WithParam.copy(nm2, getActualParams()));
nm2.setTunnelParams(WithParam.copy(nm2, getTunnelParams()));
ExpressionTool.copyLocationInfo(this, nm2);
nm2.allowAnyItem = allowAnyItem;
return nm2;
}
/*@Nullable*/
public TailCall processLeavingTail(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");
e.setXPathContext(context);
e.setErrorCode("XTDE0560");
throw e;
}
Component mode = context.getCurrentMode();
if (mode == null) {
throw new AssertionError("Current mode is null");
}
// if (context.getCurrentIterator() == null) {
// XPathException e = new XPathException("Cannot call xsl:next-match when there is no context item");
// e.setXPathContext(context);
// e.setErrorCode("XTDE0565");
// throw e;
// }
Item currentItem = context.getCurrentIterator().current();
// if (!allowAnyItem && !(currentItem instanceof NodeInfo)) {
// XPathException e = new XPathException("Cannot call xsl:next-match when context item is not a node");
// e.setXPathContext(context);
// e.setErrorCode("XTDE0565");
// throw e;
// }
Rule rule = mode.getCode().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.getCode().getBuiltInRuleSet().process(currentItem, params, tunnels, context, getLocation());
} else if (useTailRecursion) {
//Template nh = (Template)rule.getAction();
// clear all the local variables: they are no longer needed
Arrays.fill(context.getStackFrame().getStackFrameValues(), null);
return new NextMatchPackage(rule, params, tunnels, context);
} else {
TemplateRule nh = (TemplateRule) rule.getAction();
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(mode); // needed in the case where next-match is called from a named template
nh.apply(c2);
}
return null;
}
/**
* Diagnostic print of expression structure. The abstract expression tree
* is written to the supplied output destination.
*/
public void export(ExpressionPresenter out) {
out.startElement("nextMatch", this);
String flags = "";
if (useTailRecursion) {
flags = "t";
}
if (allowAnyItem) {
flags += "i";
}
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 class NextMatchPackage implements TailCall {
private Rule rule;
private ParameterSet params;
private ParameterSet tunnelParams;
private XPathContext evaluationContext;
/**
* Construct a NextMatchPackage that contains information about a call.
*
* @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(Rule rule,
ParameterSet params,
ParameterSet tunnelParams,
XPathContext evaluationContext) {
this.rule = rule;
this.params = params;
this.tunnelParams = tunnelParams;
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
*/
public TailCall processLeavingTail() throws XPathException {
TemplateRule nh = (TemplateRule) rule.getAction();
XPathContextMajor c2 = evaluationContext.newContext();
c2.setOrigin(NextMatch.this);
//c2.setOriginatingConstructType(LocationKind.TEMPLATE);
c2.setLocalParameters(params);
c2.setTunnelParameters(tunnelParams);
c2.openStackFrame(nh.getStackFrameMap());
c2.setCurrentTemplateRule(rule);
c2.setCurrentComponent(evaluationContext.getCurrentComponent());
// System.err.println("Tail call on template");
return nh.applyLeavingTail(c2);
}
}
}
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