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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.grouping.request;
import com.google.common.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 arg2;
/**
* Constructs a new instance of this class.
*
* @param attributeName The attribute name to assign to this.
*/
public ArrayAtLookup(String attributeName, GroupingExpression indexArg) {
super("array.at(" + attributeName + ", " + indexArg + ")");
this.attributeName = attributeName;
this.arg2 = indexArg;
}
/**
* Returns the name of the attribute to retrieve from the input hit.
*
* @return The attribute name.
*/
public String getAttributeName() {
return attributeName;
}
/**
* get the expression to evaluate before indexing
* @return grouping expression argument
*/
public GroupingExpression getIndexArgument() {
return arg2;
}
}
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