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.om.typecomputer.impl;
  
  import org.apache.asterix.om.typecomputer.base.AbstractResultTypeComputer;
  import org.apache.asterix.om.types.ATypeTag;
  import org.apache.asterix.om.types.AbstractCollectionType;
  import org.apache.asterix.om.types.IAType;
  import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
  import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
  
  /**
   * This function is to make a sequence of records and a singleton collection of records
   * present in a uniformed manner.
   *
   * @author yingyib
   */
  public class CollectionToSequenceTypeComputer extends AbstractResultTypeComputer {
  
      public static final CollectionToSequenceTypeComputer INSTANCE = new CollectionToSequenceTypeComputer();
  
      @Override
      protected IAType getResultType(ILogicalExpression expr, IAType... strippedInputTypes) throws AlgebricksException {
          IAType argType = strippedInputTypes[0];
          ATypeTag argTypeTag = argType.getTypeTag();
          if (argTypeTag == ATypeTag.ARRAY || argTypeTag == ATypeTag.MULTISET) {
              /** if the input is a singleton list, return it's item type if any */
              AbstractCollectionType collectionType = (AbstractCollectionType) argType;
              return collectionType.getItemType();
          } else {
              /** if the input is not a singleton list, return the original input type */
              return argType;
          }
      }
  
  }
  