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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.trans.rules;
import net.sf.saxon.expr.XPathContextMajor;
import net.sf.saxon.expr.instruct.TemplateRule;
import net.sf.saxon.expr.parser.RebindingMap;
import net.sf.saxon.om.Item;
import net.sf.saxon.pattern.Pattern;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trans.XPathException;
/**
* Rule: a template rule, or a strip-space rule used to support the implementation
*/
public class Rule {
protected Pattern pattern; // The pattern that fires this rule
protected RuleTarget action; // The action associated with this rule (usually a Template)
protected int precedence; // The import precedence
protected int minImportPrecedence;// The minimum import precedence to be considered by xsl:apply-imports
protected double priority; // The priority of the rule
protected Rule next; // The next rule after this one in the chain of rules
protected int sequence; // The relative position of this rule, its position in declaration order
protected int part; // The relative position of this rule relative to others formed by splitting
// on a union pattern
private boolean alwaysMatches; // True if the pattern does not need to be tested, because the rule
// is on a rule-chain such that the pattern is necessarily satisfied
private int rank; // Indicates the relative precedence/priority of a rule within a mode;
// used for quick comparison
public Rule() {}
/**
* Create a Rule.
*
* @param p the pattern that this rule matches
* @param o the object invoked by this rule (usually a Template)
* @param prec the precedence of the rule
* @param min the minumum import precedence for xsl:apply-imports
* @param prio the priority of the rule
* @param seq a sequence number for ordering of rules
*/
public Rule(/*@NotNull*/ Pattern p, /*@NotNull*/ RuleTarget o, int prec, int min, double prio, int seq, int part) {
pattern = p;
action = o;
precedence = prec;
minImportPrecedence = min;
priority = prio;
next = null;
sequence = seq;
this.part = part;
o.registerRule(this);
}
/**
* Copy a rule, including optionally the chain of rules linked to it
*
* @param r the rule to be copied
* @param copyChain true if the whole chain of rules is to be copied
*/
protected void copyFrom(Rule r, boolean copyChain) {
pattern = r.pattern.copy(new RebindingMap());
action = r.action instanceof TemplateRule ? ((TemplateRule) r.action).copy() : r.action;
precedence = r.precedence;
minImportPrecedence = r.minImportPrecedence;
priority = r.priority;
sequence = r.sequence;
part = r.part;
if (r.next == null || !copyChain) {
next = null;
} else {
next = r.next.copy(true);
}
action.registerRule(this);
}
public Rule copy(boolean copyChain) {
Rule r2 = new Rule();
r2.copyFrom(this, copyChain);
return r2;
}
public int getSequence() {
return sequence;
}
public int getPartNumber() {
return part;
}
public void setAction(/*@NotNull*/ RuleTarget action) {
this.action = action;
}
/*@NotNull*/
public RuleTarget getAction() {
return action;
}
/*@Nullable*/
public Rule getNext() {
return next;
}
public void setNext( /*@Nullable*/Rule next) {
this.next = next;
}
/*@NotNull*/
public Pattern getPattern() {
return pattern;
}
public void setPattern(Pattern pattern) {
this.pattern = pattern;
}
public int getPrecedence() {
return precedence;
}
public int getMinImportPrecedence() {
return minImportPrecedence;
}
public double getPriority() {
return priority;
}
public void setAlwaysMatches(boolean matches) {
alwaysMatches = matches;
}
public boolean isAlwaysMatches() {
return alwaysMatches;
}
public void setRank(int rank) {
this.rank = rank;
}
public int getRank() {
return rank;
}
/**
* Export this rule
* @param out the destination for the export
* @param modeStreamable if the mode for this rule is streamable (should be EE only?)
*/
public void export(ExpressionPresenter out, boolean modeStreamable) throws XPathException {
RuleTarget target = getAction();
TemplateRule template = null;
if (target instanceof TemplateRule) {
template = (TemplateRule) target;
int s = out.startElement("templateRule");
out.emitAttribute("prec", getPrecedence() + "");
out.emitAttribute("prio", getPriority() + "");
out.emitAttribute("seq", getSequence() + "");
if (part != 0) {
out.emitAttribute("part", "" + part);
}
out.emitAttribute("rank", "" + getRank());
out.emitAttribute("minImp", getMinImportPrecedence() + "");
out.emitAttribute("slots", template.getStackFrameMap().getNumberOfVariables() + "");
out.emitAttribute("matches", pattern.getItemType().getFullAlphaCode());
template.explainProperties(out);
exportOtherProperties(out);
out.setChildRole("match");
getPattern().export(out);
if (template.getBody() != null) {
out.setChildRole("action");
template.getBody().export(out);
}
int e = out.endElement();
if (s != e) {
throw new IllegalStateException(
"exported expression tree unbalanced in template at line " +
(template != null ?
template.getLineNumber() + " of " + template.getSystemId() : ""));
}
} else {
target.export(out);
}
}
/**
* Add other exported properties as required
* @param out the export destination
*/
public void exportOtherProperties(ExpressionPresenter out) throws XPathException {}
/**
* Rules have an ordering, based on their precedence and priority. This method compares
* them using the precomputed rank value.
*
* @param other Another rule whose ordering rank is to be compared with this one
* @return <0 if this rule has lower rank, that is if it has lower precedence or equal
* precedence and lower priority. 0 if the two rules have equal precedence and
* priority. >0 if this rule has higher rank in precedence/priority order
*/
public int compareRank(Rule other) {
return rank - other.rank;
}
/**
* Rules have an ordering, based on their precedence and priority.
*
* @param other Another rule whose ordering rank is to be compared with this one
* @return <0 if this rule has lower rank, that is if it has lower precedence or equal
* precedence and lower priority. 0 if the two rules have equal precedence and
* priority. >0 if this rule has higher rank in precedence/priority order
*/
public int compareComputedRank(Rule other) {
if (precedence == other.precedence) {
return Double.compare(priority, other.priority);
} else if (precedence < other.precedence) {
return -1;
} else {
return +1;
}
}
public boolean matches(Item item, XPathContextMajor context) throws XPathException {
return alwaysMatches || pattern.matches(item, context);
}
}