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.cql3.CqlBuilder;
  import org.apache.cassandra.db.marshal.AbstractType;
  import org.apache.cassandra.exceptions.InvalidRequestException;
  import org.apache.cassandra.transport.ProtocolVersion;
  
  /**
   * An internal function used to hold the partial application of another function to only some of its parameters.
   *
   * @see ScalarFunction#partialApplication(ProtocolVersion, List)
   */
  final class PartiallyAppliedScalarFunction extends NativeScalarFunction implements PartialScalarFunction
  {
      private final ScalarFunction function;
      private final List<ByteBuffer> partialParameters;
  
      PartiallyAppliedScalarFunction(ScalarFunction function, List<ByteBuffer> partialParameters, int unresolvedCount)
      {
          // Note that we never register those function, there are just used internally, so the name doesn't matter much
          super("__partial_application__", function.returnType(), computeArgTypes(function, partialParameters, unresolvedCount));
          this.function = function;
          this.partialParameters = partialParameters;
      }
  
      @Override
      public boolean isMonotonic()
      {
          return function.isNative() ? ((NativeScalarFunction) function).isPartialApplicationMonotonic(partialParameters)
                                     : function.isMonotonic();
      }
  
      @Override
      public boolean isPure()
      {
          return function.isPure();
      }
  
      @Override
      public Function getFunction()
      {
          return function;
      }
  
      @Override
      public Arguments newArguments(ProtocolVersion version)
      {
          return new PartialFunctionArguments(version, function, partialParameters, argTypes.size());
      }
  
      @Override
      public List<ByteBuffer> getPartialArguments()
      {
          return partialParameters;
      }
  
      private static AbstractType<?>[] computeArgTypes(ScalarFunction function, List<ByteBuffer> partialParameters, int unresolvedCount)
      {
          AbstractType<?>[] argTypes = new AbstractType<?>[unresolvedCount];
          int arg = 0;
          for (int i = 0; i < partialParameters.size(); i++)
          {
              if (partialParameters.get(i) == UNRESOLVED)
                  argTypes[arg++] = function.argTypes().get(i);
          }
          return argTypes;
      }
  
      @Override
      public ByteBuffer execute(Arguments arguments) throws InvalidRequestException
      {
          return function.execute(arguments);
      }
  
      @Override
      public String toString()
      {
          CqlBuilder b = new CqlBuilder().append(function.name()).append(" : (");
  
          List<AbstractType<?>> types = function.argTypes();
          for (int i = 0, m = types.size(); i < m; i++)
          {
              if (i > 0)
                  b.append(", ");
              b.append(toCqlString(types.get(i)));
              if (partialParameters.get(i) != Function.UNRESOLVED)
                  b.append("(constant)");
          }
          b.append(") -> ").append(returnType);
          return b.toString();
      }
  
      /**
       * The arguments for a {@code PartiallyAppliedScalarFunction}.
       *
       */
      private static final class PartialFunctionArguments implements Arguments
      {
          /**
           * The decorated arguments.
           */
          private final Arguments arguments;
  
          /**
           * The position of the unresolved arguments.
           */
          private final int[] mapping;
  
          public PartialFunctionArguments(ProtocolVersion version, ScalarFunction function, List<ByteBuffer> partialArguments, int unresolvedCount)
          {
              arguments = function.newArguments(version);
              mapping = new int[unresolvedCount];
              int mappingIndex = 0;
              for (int i = 0, m = partialArguments.size(); i < m; i++)
              {
                  ByteBuffer argument = partialArguments.get(i);
                  if (argument != Function.UNRESOLVED)
                  {
                      arguments.set(i, argument);
                  }
                  else
                  {
                      mapping[mappingIndex++] = i;
                  }
              }
          }
  
          @Override
          public ProtocolVersion getProtocolVersion()
          {
              return arguments.getProtocolVersion();
          }
  
          @Override
          public void set(int i, ByteBuffer buffer)
          {
              arguments.set(mapping[i], buffer);
          }
  
          @Override
          public boolean containsNulls()
          {
              return arguments.containsNulls();
          }
  
          @Override
          public <T> T get(int i)
          {
              return arguments.get(i);
          }
  
          @Override
          public int size()
          {
              return arguments.size();
          }
      }
  }
  