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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.query;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.stream.Collectors;
import com.yahoo.compress.IntegerCompressor;
/**
* A set of words with differing exactness scores to be used for literal boost ranking.
*
* @author Steinar Knutsen
*/
public class WordAlternativesItem extends TermItem {
private List<Alternative> alternatives;
public WordAlternativesItem(String indexName, boolean isFromQuery, Substring origin, Collection<Alternative> terms) {
super(indexName, isFromQuery, origin);
setAlternatives(terms);
}
public void setAlternatives(Collection<Alternative> terms) {
this.alternatives = uniqueAlternatives(terms);
}
private static List<Alternative> uniqueAlternatives(Collection<Alternative> terms) {
List<Alternative> uniqueTerms = new ArrayList<>(terms.size());
for (Alternative term : terms) {
int i = Collections.binarySearch(uniqueTerms, term, (t0, t1) -> t0.word.compareTo(t1.word));
if (i >= 0) {
Alternative old = uniqueTerms.get(i);
if (old.exactness < term.exactness) {
uniqueTerms.set(i, term);
}
} else {
uniqueTerms.add(~i, term);
}
}
return List.copyOf(uniqueTerms);
}
@Override
public String stringValue() {
StringBuilder builder = new StringBuilder();
builder.append("[ ");
for (Alternative a : alternatives) {
builder.append(a.word).append("(").append(a.exactness).append(") ");
}
builder.append("]");
return builder.toString();
}
@Override
public boolean isStemmed() {
return true;
}
@Override
public int getNumWords() {
return 1;
}
@Override
public void setValue(String value) {
throw new UnsupportedOperationException("Semantics for setting to a string would be brittle, use setAlternatives()");
}
@Override
public String getRawWord() {
if (getOrigin() == null) {
return stringValue();
} else {
return getOrigin().getValue();
}
}
@Override
public boolean isWords() {
return true;
}
@Override
public String getIndexedString() {
return alternatives.stream().map((x) -> x.word).collect(Collectors.joining(" "));
}
@Override
public ItemType getItemType() {
return ItemType.WORD_ALTERNATIVES; // placeholder
}
@Override
public String getName() {
return "WORD_ALTERNATIVES";
}
/**
* Return an immutable snapshot of the contained terms. This list will not reflect later changes to the item.
*
* @return an immutable list of word alternatives and their respective scores
*/
public List<Alternative> getAlternatives() {
return alternatives;
}
@Override
public void encodeThis(ByteBuffer target) {
super.encodeThis(target);
IntegerCompressor.putCompressedPositiveNumber(alternatives.size(), target);
for (Alternative a : alternatives) {
Item p = new PureWeightedString(a.word, (int) (getWeight() * a.exactness + 0.5));
p.setFilter(isFilter());
p.encode(target);
}
}
/**
* Add a new alternative iff the term string is not already present with an
* equal or higher exactness score. If the term string is present with a
* lower exactness score, the new, higher score will take precedence.
*
* @param term one of several string interpretations of the input word
* @param exactness how close the term string matches what the user input
*/
public void addTerm(String term, double exactness) {
// do note, Item is Cloneable, and overwriting the reference is what
// saves us from overriding the method
if (alternatives.stream().anyMatch((a) -> a.word.equals(term) && a.exactness >= exactness )) return;
List<Alternative> newTerms = new ArrayList<>(alternatives.size() + 1);
newTerms.addAll(alternatives);
newTerms.add(new Alternative(term, exactness));
setAlternatives(newTerms);
}
@Override
public WordAlternativesItem clone() {
var clone = (WordAlternativesItem)super.clone();
clone.alternatives = new ArrayList(this.alternatives);
return clone;
}
@Override
public boolean equals(Object other) {
if ( ! super.equals(other)) return false;
return this.alternatives.equals(((WordAlternativesItem)other).alternatives);
}
@Override
public int hashCode() {
return Objects.hash(super.hashCode(), alternatives);
}
/** A word alternative. This is a value object. */
public static final class Alternative {
public final String word;
public final double exactness;
public Alternative(String word, double exactness) {
super();
this.word = word;
this.exactness = exactness;
}
@Override
public String toString() {
return "Alternative [word=" + word + ", exactness=" + exactness + "]";
}
@Override
public boolean equals(Object o) {
if ( ! (o instanceof Alternative other)) return false;
if ( ! Objects.equals(this.word, other.word)) return false;
if (this.exactness != other.exactness) return false;
return true;
}
@Override
public int hashCode() {
return Objects.hash(word, exactness);
}
}
}
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