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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.search.grouping.request;
import com.yahoo.api.annotations.Beta;
/**
* Represents access of array element in a document attribute in a {@link GroupingExpression}.
*
* The first argument should be the name of an array attribute in the
* input {@link com.yahoo.search.result.Hit}, while the second
* argument is evaluated as an integer and used as the index in that array.
* If the index argument is less than 0 returns the first array element;
* if the index is greater than or equal to size(array) returns the last array element;
* if the array is empty returns 0 (or NaN?).
*
* @author arnej27959
*/
@Beta
public class ArrayAtLookup extends DocumentValue {
private final String attributeName;
private final GroupingExpression indexArgument;
/**
* Constructs a new instance of this class.
*
* @param attributeName the attribute name to assign to this.
*/
public ArrayAtLookup(String attributeName, GroupingExpression indexArg) {
this(null, null, attributeName, indexArg);
}
private ArrayAtLookup(String label, Integer level, String attributeName, GroupingExpression indexArgument) {
super("array.at(" + attributeName + ", " + indexArgument + ")", label, level);
this.attributeName = attributeName;
this.indexArgument = indexArgument;
}
@Override
public ArrayAtLookup copy() {
return new ArrayAtLookup(getLabel(), getLevelOrNull(), getAttributeName(), getIndexArgument().copy());
}
/** Returns the name of the attribute to retrieve from the input hit */
public String getAttributeName() {
return attributeName;
}
/** Return the expression to evaluate before indexing */
public GroupingExpression getIndexArgument() {
return indexArgument;
}
}
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