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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.prelude.semantics.rule;
import com.yahoo.prelude.querytransform.PhraseMatcher;
import com.yahoo.prelude.semantics.RuleBase;
import com.yahoo.prelude.semantics.RuleBaseException;
import com.yahoo.prelude.semantics.engine.Choicepoint;
import com.yahoo.prelude.semantics.engine.EvaluationException;
import com.yahoo.prelude.semantics.engine.FlattenedItem;
import com.yahoo.prelude.semantics.engine.RuleEvaluation;
import com.yahoo.protect.Validator;
/**
* A reference to a named condition
*
* @author bratseth
*/
public class ConditionReference extends Condition {
/** The name of the referenced rule */
private String conditionName;
/**
* The actual condition referenced by this, or null if not initialized or not found,
* or if this is really an automata reference
*/
private NamedCondition namedCondition;
/**
* True if this condition should be looked up in the automata
* annotations of the item instead of by reference to another item
*/
private boolean automataLookup = false;
public ConditionReference(String conditionName) {
this(null,conditionName);
}
public ConditionReference(String label,String conditionName) {
super(label);
Validator.ensureNotNull("Name of referenced condition",conditionName);
this.conditionName = conditionName;
setContextName(conditionName);
}
/** Returns the name of the referenced rule, never null */
public String getConditionName() { return conditionName; }
public void setConditionName(String name) { this.conditionName = name; }
public boolean doesMatch(RuleEvaluation e) {
if (automataLookup) return automataMatch(e);
if (namedCondition == null)
throw new EvaluationException("Condition reference '" + conditionName + "' not found or not initialized");
return namedCondition.matches(e);
}
private boolean automataMatch(RuleEvaluation e) {
FlattenedItem current = e.currentItem();
if (current == null) return false;
Object annotation = current.getItem().getAnnotation(conditionName);
if (annotation == null) return false;
if (! (annotation instanceof PhraseMatcher.Phrase)) return false;
PhraseMatcher.Phrase phrase = (PhraseMatcher.Phrase)annotation;
Choicepoint choicePoint = e.getChoicepoint(this,true);
boolean matches = automataMatchPhrase(phrase,e);
if (!matches && e.isInNegation()) { // TODO: Temporary hack! Works for single items only
e.addMatch(current,null);
}
if ((!matches && !e.isInNegation() || (matches && e.isInNegation())))
choicePoint.backtrackPosition();
return matches;
}
private boolean automataMatchPhrase(PhraseMatcher.Phrase phrase, RuleEvaluation e) {
for (PhraseMatcher.Phrase.MatchIterator i = phrase.itemIterator(); i.hasNext(); ) {
i.next();
FlattenedItem current = e.currentItem();
if (current == null) return false;
if (!labelMatches(e.currentItem().getItem(),e)) return false;
if (!e.isInNegation())
e.addMatch(current, i.getReplace());
e.next();
}
if (phrase.getLength() > phrase.getBackedLength()) return false; // The underlying composite item has changed
return true;
}
public void makeReferences(RuleBase ruleBase) {
namedCondition = ruleBase.getCondition(conditionName);
if (namedCondition == null) { // Then this may reference some automata value, if we have an automata
if (ruleBase.usesAutomata())
automataLookup = true;
else
throw new RuleBaseException("Referenced condition '" + conditionName +
"' does not exist in " + ruleBase);
}
}
protected boolean hasOpenChoicepoint(RuleEvaluation e) {
if (namedCondition == null) return false;
return namedCondition.getCondition().hasOpenChoicepoint(e);
}
protected boolean isDefaultContextName() {
return getContextName() == null || getContextName().equals(conditionName);
}
@Override
protected String toInnerString() {
return "[" + conditionName + "]";
}
}
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