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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.prelude.query;
import com.yahoo.protect.Validator;
import java.util.Collection;
/**
* An Item where each child is an <i>alternative</i> which can be matched.
* Produces the same recall as Or, but differs in that the relevance of a match
* does not increase if more than one children is matched: With Equiv, matching one child perfectly is a perfect match.
* <p>
* This can only have Word, WordAlternatives, Exact, Int or Phrase children.
*
* @author havardpe
*/
public class EquivItem extends CompositeTaggableItem {
/** Makes an EQUIV item with no children */
public EquivItem() {}
/**
* Creates an EQUIV with the given item as child. The new EQUIV will take connectivity,
* significance and weight from the given item.
*
* @param item will be modified and added as a child
*/
public EquivItem(Item item) {
addItem(item);
// steal other item's connectivity:
if (item.connectedItem != null) {
setConnectivity(item.connectedItem, item.connectivity);
item.connectedItem = null;
item.connectivity = 0.0;
}
TaggableItem back = (TaggableItem)item.connectedBacklink;
if (back != null) {
back.setConnectivity(this, back.getConnectivity());
item.connectedBacklink = null;
}
// steal other item's significance:
if (item.explicitSignificance) {
setSignificance(item.significance);
}
// steal other item's weight:
setWeight(item.getWeight());
// we have now stolen all the other item's unique id needs:
item.setHasUniqueID(false);
}
/**
* Creates an EQUIV with the given item and a set of alternate words as children.
* The new EQUIV will take connectivity, significance and weight from the given item.
*
* @param item will be modified and added as a child
* @param words set of words to create WordItems from
*/
public EquivItem(Item item, Collection<String> words) {
this(item);
String idx = ((IndexedItem)item).getIndexName();
for (String word : words) {
WordItem witem = new WordItem(word, idx);
addItem(witem);
}
}
@Override
public ItemType getItemType() {
return ItemType.EQUIV;
}
@Override
public String getName() {
return "EQUIV";
}
@Override
protected void adding(Item item) {
super.adding(item);
Validator.ensure("Could not add an item of type " + item.getItemType() +
": Equiv can only have word, wordAlternatives, int, exact, or phrase as children",
acceptsChildrenOfType(item.getItemType()));
}
@Override
public boolean acceptsItemsOfType(ItemType itemType) {
return acceptsChildrenOfType(itemType);
}
/** Returns true if this accepts child items of the given type */
public static boolean acceptsChildrenOfType(ItemType itemType) {
return itemType == ItemType.WORD ||
itemType == ItemType.WORD_ALTERNATIVES ||
itemType == ItemType.INT ||
itemType == ItemType.EXACT ||
itemType == ItemType.PHRASE;
}
}
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