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.SqlSplittableAggFunction;
  import org.apache.calcite.sql.type.OperandTypes;
  import org.apache.calcite.sql.type.ReturnTypes;
  import org.apache.calcite.util.Optionality;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import static com.google.common.base.Preconditions.checkArgument;
  
  /**
   * Definition of the <code>ANY_VALUE</code> aggregate functions,
   * returning any one of the values which go into it.
   */
  public class SqlAnyValueAggFunction extends SqlAggFunction {
  
    //~ Instance fields --------------------------------------------------------
  
    //~ Constructors -----------------------------------------------------------
  
    /** Creates a SqlAnyValueAggFunction. */
    public SqlAnyValueAggFunction(SqlKind kind) {
      super(kind.name(),
          null,
          kind,
          ReturnTypes.ARG0_NULLABLE_IF_EMPTY,
          null,
          OperandTypes.ANY,
          SqlFunctionCategory.SYSTEM,
          false,
          false,
          Optionality.FORBIDDEN);
      checkArgument(kind == SqlKind.ANY_VALUE);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public <T extends Object> @Nullable T unwrap(Class<T> clazz) {
      if (clazz.isInstance(SqlSplittableAggFunction.SelfSplitter.INSTANCE)) {
        return clazz.cast(SqlSplittableAggFunction.SelfSplitter.INSTANCE);
      }
      return super.unwrap(clazz);
    }
  
    @Override public Optionality getDistinctOptionality() {
      return Optionality.IGNORED;
    }
  
    @Override public SqlAggFunction getRollup() {
      return this;
    }
  }
  