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 org.apache.cassandra.exceptions.InvalidRequestException;
  import org.apache.cassandra.transport.ProtocolVersion;
  
  /**
   * Determines a single output value based on any number of input values.
   */
  public interface ScalarFunction extends Function
  {
      public boolean isCalledOnNullInput();
  
      /**
       * Checks if the function is monotonic.
       *
       *<p>A function is monotonic if it is either entirely nonincreasing or nondecreasing given an ordered set of inputs.</p>
       *
       * @return {@code true} if the function is monotonic {@code false} otherwise.
       */
      public default boolean isMonotonic()
      {
          return false;
      }
  
      /**
       * Applies this function to the specified arguments.
       *
       * @param arguments the input arguments for the function
       * @return the result of applying this function to the arguments
       * @throws InvalidRequestException if this function cannot not be applied to the arguments
       */
      public ByteBuffer execute(Arguments arguments) throws InvalidRequestException;
  
      /**
       * Does a partial application of the function. That is, given only some of the arguments of the function provided,
       * return a new function that only expect the arguments not provided.
       * <p>
       * To take an example, if you consider the function
       * <pre>
       *     text foo(int a, text b, text c, int d)
       * </pre>
       * then {@code foo.partialApplication([3, <ommitted>, 'bar', <omitted>])} will return a function {@code bar} of signature:
       * <pre>
       *     text bar(text b, int d)
       * </pre>
       * and such that for any value of {@code b} and {@code d}, {@code bar(b, d) == foo(3, b, 'bar', d)}.
       *
       * @param protocolVersion protocol version used for arguments
       * @param partialArguments a list of input arguments for the function where some arguments can be {@link #UNRESOLVED}.
       *                         The input <b>must</b> be of size {@code this.argsType().size()}. For convenience, it is
       *                         allowed both to pass a list with all arguments being {@link #UNRESOLVED} (the function is
       *                         then returned directly) and with none of them unresolved (in which case, if the function is pure,
       *                         it is computed and a dummy no-arg function returning the result is returned).
       * @return a function corresponding to the partial application of this function to the arguments of
       * {@code partialArguments} that are not {@link #UNRESOLVED}.
       */
      default ScalarFunction partialApplication(ProtocolVersion protocolVersion, List<ByteBuffer> partialArguments)
      {
          int unresolvedCount = 0;
          for (ByteBuffer argument : partialArguments)
          {
              if (argument == UNRESOLVED)
                  ++unresolvedCount;
          }
  
          if (unresolvedCount == argTypes().size())
              return this;
  
          if (isPure() && unresolvedCount == 0)
          {
              Arguments arguments = newArguments(protocolVersion);
              for (int i = 0, m = partialArguments.size(); i < m; i++)
              {
                  arguments.set(i, partialArguments.get(i));
              }
  
              return new PreComputedScalarFunction(returnType(),
                                                   execute(arguments),
                                                   protocolVersion,
                                                   this,
                                                   partialArguments);
          }
  
          return new PartiallyAppliedScalarFunction(this, partialArguments, unresolvedCount);
      }
  }
  