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.asterix.runtime.evaluators.functions;
  
  import org.apache.asterix.builders.IAsterixListBuilder;
  import org.apache.asterix.common.annotations.MissingNullInOutFunction;
  import org.apache.asterix.om.functions.BuiltinFunctions;
  import org.apache.asterix.om.functions.IFunctionDescriptor;
  import org.apache.asterix.om.functions.IFunctionDescriptorFactory;
  import org.apache.asterix.om.functions.IFunctionTypeInferer;
  import org.apache.asterix.om.types.IAType;
  import org.apache.asterix.runtime.evaluators.base.AbstractScalarFunctionDynamicDescriptor;
  import org.apache.asterix.runtime.functions.FunctionTypeInferers;
  import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
  import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluator;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
  import org.apache.hyracks.api.context.IEvaluatorContext;
  import org.apache.hyracks.api.exceptions.HyracksDataException;
  import org.apache.hyracks.data.std.api.IPointable;
  
  /**
   * <pre>
   * array_concat(list1, list2, ...) returns a new list with all the values of all lists appended in order into the
   * new list. Items of the lists can be null or missing (both are added as a null value).
   *
   * It throws an error at compile time if the number of arguments < 2
   *
   * It returns (or throws an error at runtime) in order:
   * 1. missing, if any argument is missing.
   * 2. an error if the input lists are not of the same type (one is an ordered list while the other is unordered).
   * 3. null, if any input list is null or is not a list.
   * 4. otherwise, a new list.
   *
   * </pre>
   */
  
  @MissingNullInOutFunction
  public class ArrayConcatDescriptor extends AbstractScalarFunctionDynamicDescriptor {
      private static final long serialVersionUID = 1L;
      private IAType[] argTypes;
  
      public static final IFunctionDescriptorFactory FACTORY = new IFunctionDescriptorFactory() {
          @Override
          public IFunctionDescriptor createFunctionDescriptor() {
              return new ArrayConcatDescriptor();
          }
  
          @Override
          public IFunctionTypeInferer createFunctionTypeInferer() {
              return FunctionTypeInferers.SET_ARGUMENTS_TYPE;
          }
      };
  
      @Override
      public FunctionIdentifier getIdentifier() {
          return BuiltinFunctions.ARRAY_CONCAT;
      }
  
      @Override
      public IScalarEvaluatorFactory createEvaluatorFactory(final IScalarEvaluatorFactory[] args)
              throws AlgebricksException {
          return new IScalarEvaluatorFactory() {
              private static final long serialVersionUID = 1L;
  
              @Override
              public IScalarEvaluator createScalarEvaluator(final IEvaluatorContext ctx) throws HyracksDataException {
                  return new ArrayConcatEval(args, ctx);
              }
          };
      }
  
      @Override
      public void setImmutableStates(Object... states) {
          argTypes = (IAType[]) states;
      }
  
      public class ArrayConcatEval extends AbstractArrayProcessArraysEval {
  
          ArrayConcatEval(IScalarEvaluatorFactory[] args, IEvaluatorContext ctx) throws HyracksDataException {
              super(args, ctx, sourceLoc, argTypes);
          }
  
          @Override
          protected void init() {
              // do nothing
          }
  
          @Override
          protected void finish(IAsterixListBuilder listBuilder) {
              // do nothing
          }
  
          @Override
          protected void release() {
              // do nothing
          }
  
          @Override
          protected boolean processItem(IPointable item, int listIndex, IAsterixListBuilder listBuilder)
                  throws HyracksDataException {
              listBuilder.addItem(item);
              // listBuilder always copies the item, so we're not using the supplied item
              return false;
          }
      }
  }
  