content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to you under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.calcite.sql.fun;
  
  import org.apache.calcite.sql.SqlAggFunction;
  import org.apache.calcite.sql.SqlFunctionCategory;
  import org.apache.calcite.sql.SqlKind;
  import org.apache.calcite.sql.type.OperandTypes;
  import org.apache.calcite.sql.type.ReturnTypes;
  import org.apache.calcite.util.Optionality;
  
  /**
   * <code>NTH_VALUE</code> windowed aggregate function
   * returns the value of an expression evaluated at the {@code n}th row of the
   * window frame.
   */
  public class SqlNthValueAggFunction extends SqlAggFunction {
    public SqlNthValueAggFunction(SqlKind kind) {
      super(kind.name(), null, kind, ReturnTypes.ARG0_NULLABLE_IF_EMPTY,
          null, OperandTypes.ANY_NUMERIC, SqlFunctionCategory.NUMERIC, false,
          true, Optionality.FORBIDDEN);
    }
  
    @Override public boolean allowsNullTreatment() {
      return true;
    }
  }
  