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 com.google.common.base.Objects;
  
  import org.apache.cassandra.cql3.AssignmentTestable;
  import org.apache.cassandra.cql3.CQL3Type;
  import org.apache.cassandra.cql3.CQL3Type.Tuple;
  import org.apache.cassandra.cql3.ColumnSpecification;
  import org.apache.cassandra.cql3.CqlBuilder;
  import org.apache.cassandra.db.marshal.AbstractType;
  
  import org.apache.commons.lang3.text.StrBuilder;
  
  import static java.util.stream.Collectors.toList;
  
  /**
   * Base class for our native/hardcoded functions.
   */
  public abstract class AbstractFunction implements Function
  {
      protected final FunctionName name;
      protected final List<AbstractType<?>> argTypes;
      protected final AbstractType<?> returnType;
  
      protected AbstractFunction(FunctionName name, List<AbstractType<?>> argTypes, AbstractType<?> returnType)
      {
          this.name = name;
          this.argTypes = argTypes;
          this.returnType = returnType != null ? returnType.unwrap() : null;
      }
  
      public FunctionName name()
      {
          return name;
      }
  
      public List<AbstractType<?>> argTypes()
      {
          return argTypes;
      }
  
      public AbstractType<?> returnType()
      {
          return returnType;
      }
  
      public List<String> argumentsList()
      {
          return argTypes().stream()
                           .map(AbstractType::asCQL3Type)
                           .map(CQL3Type::toString)
                           .collect(toList());
      }
  
      @Override
      public boolean equals(Object o)
      {
          if (!(o instanceof AbstractFunction))
              return false;
  
          AbstractFunction that = (AbstractFunction)o;
          return Objects.equal(this.name, that.name)
              && Objects.equal(this.argTypes, that.argTypes)
              && Objects.equal(this.returnType, that.returnType);
      }
  
      public void addFunctionsTo(List<Function> functions)
      {
          functions.add(this);
      }
  
      public boolean referencesUserType(ByteBuffer name)
      {
          return false;
      }
  
      @Override
      public int hashCode()
      {
          return Objects.hashCode(name, argTypes, returnType);
      }
  
      public final AssignmentTestable.TestResult testAssignment(String keyspace, ColumnSpecification receiver)
      {
          // We should ignore the fact that the receiver type is frozen in our comparison as functions do not support
          // frozen types for return type
          AbstractType<?> returnType = returnType();
          if (receiver.type.isFreezable() && !receiver.type.isMultiCell())
              returnType = returnType.freeze();
  
          if (receiver.type.equals(returnType))
              return AssignmentTestable.TestResult.EXACT_MATCH;
  
          if (receiver.type.isValueCompatibleWith(returnType))
              return AssignmentTestable.TestResult.WEAKLY_ASSIGNABLE;
  
          return AssignmentTestable.TestResult.NOT_ASSIGNABLE;
      }
  
      @Override
      public AbstractType<?> getCompatibleTypeIfKnown(String keyspace)
      {
          return returnType();
      }
  
      @Override
      public String toString()
      {
          return new CqlBuilder().append(name)
                                .append(" : (")
                                .appendWithSeparators(argTypes, (b, t) -> b.append(toCqlString(t)), ", ")
                                .append(") -> ")
                                .append(returnType)
                                .toString();
      }
  
      public String elementKeyspace()
      {
          return name.keyspace;
      }
  
      public String elementName()
      {
          return new CqlBuilder().append(name.name)
                                 .append('(')
                                 .appendWithSeparators(argTypes, (b, t) -> b.append(toCqlString(t)), ", ")
                                 .append(')')
                                 .toString();
      }
  
      /**
       * Converts the specified type into its CQL representation.
       *
       * <p>For user function and aggregates tuples need to be handle in a special way as they are frozen by nature
       * but the frozen keyword should not appear in their CQL definition.</p>
       *
       * @param type the type
       * @return the CQL representation of the specified type
       */
      protected String toCqlString(AbstractType<?> type)
      {
          return type.isTuple() ? ((Tuple) type.asCQL3Type()).toString(false)
                                : type.asCQL3Type().toString();
      }
  
      @Override
      public String columnName(List<String> columnNames)
      {
          return new StrBuilder(name().toString()).append('(')
                                                  .appendWithSeparators(columnNames, ", ")
                                                  .append(')')
                                                  .toString();
      }
  
      /*
       * We need to compare the CQL3 representation of the type because comparing
       * the AbstractType will fail for example if a UDT has been changed.
       * Reason is that UserType.equals() takes the field names and types into account.
       * Example CQL sequence that would fail when comparing AbstractType:
       *    CREATE TYPE foo ...
       *    CREATE FUNCTION bar ( par foo ) RETURNS foo ...
       *    ALTER TYPE foo ADD ...
       * or
       *    ALTER TYPE foo ALTER ...
       * or
       *    ALTER TYPE foo RENAME ...
       */
      public boolean typesMatch(List<AbstractType<?>> types)
      {
          if (argTypes().size() != types.size())
              return false;
  
          for (int i = 0; i < argTypes().size(); i++)
              if (!typesMatch(argTypes().get(i), types.get(i)))
                  return false;
  
          return true;
      }
  
      private static boolean typesMatch(AbstractType<?> t1, AbstractType<?> t2)
      {
          return t1.freeze().asCQL3Type().toString().equals(t2.freeze().asCQL3Type().toString());
      }
  }
  