// This file is part of OpenTSDB.
// Copyright (C) 2015 The OpenTSDB Authors.
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 2.1 of the License, or (at your
// option) any later version. This program is distributed in the hope that it
// will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
// General Public License for more details. You should have received a copy
// of the GNU Lesser General Public License along with this program. If not,
// see <http://www.gnu.org/licenses/>.
package net.opentsdb.query.expression;
import java.util.List;
import net.opentsdb.core.DataPoints;
import net.opentsdb.core.TSQuery;
/**
* The interface for various expressions/functions used when querying OpenTSDB.
* @since 2.3
*/
public interface Expression {
/**
* Computes a set of results given the results of a {@link TSQuery} that may
* include multiple metrics and/or group by result sets.
* @param data_query The original query from the user
* @param results The results of the query
* @param params Parameters parsed from the expression endpoint related to
* the implementing function
* @return An array of data points resulting from the implementation
*/
public DataPoints[] evaluate(TSQuery data_query,
List<DataPoints[]> results, List<String> params);
/**
* TODO - document me!
* @param params
* @param inner_expression
* @return
*/
public String writeStringField(List<String> params, String inner_expression);
}