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.cassandra.cql3.functions;
  
  import java.nio.ByteBuffer;
  import java.util.List;
  import java.util.Optional;
  
  import org.apache.cassandra.cql3.AssignmentTestable;
  import org.apache.cassandra.db.marshal.AbstractType;
  import org.apache.cassandra.schema.Difference;
  import org.apache.cassandra.transport.ProtocolVersion;
  import org.github.jamm.Unmetered;
  
  @Unmetered
  public interface Function extends AssignmentTestable
  {
      /**
       * A marker buffer used to represent function parameters that cannot be resolved at some stage of CQL processing.
       * This is used for partial function application in particular.
       */
      public static final ByteBuffer UNRESOLVED = ByteBuffer.allocate(0);
  
      public FunctionName name();
      public List<AbstractType<?>> argTypes();
      public AbstractType<?> returnType();
  
      /**
       * Checks whether the function is a native/hard coded one or not.
       *
       * @return {@code true} if the function is a native/hard coded one, {@code false} otherwise.
       */
      public boolean isNative();
  
      /**
       * Checks whether the function is a pure function (as in doesn't depend on, nor produces side effects) or not.
       *
       * @return {@code true} if the function is a pure function, {@code false} otherwise.
       */
      public boolean isPure();
  
      /**
       * Checks whether the function is an aggregate function or not.
       *
       * @return {@code true} if the function is an aggregate function, {@code false} otherwise.
       */
      public boolean isAggregate();
  
      public void addFunctionsTo(List<Function> functions);
  
      public boolean referencesUserType(ByteBuffer name);
  
      /**
       * Returns the name of the function to use within a ResultSet.
       *
       * @param columnNames the names of the columns used to call the function
       * @return the name of the function to use within a ResultSet
       */
      public String columnName(List<String> columnNames);
  
      /**
       * Creates some new input arguments for this function.
       *
       * @param version the protocol version
       * @return some new input arguments for this function
       */
      Arguments newArguments(ProtocolVersion version);
  
      public default Optional<Difference> compare(Function other)
      {
          throw new UnsupportedOperationException();
      }
  }
  