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.IResultTypeComputer;
  import org.apache.asterix.om.typecomputer.base.TypeCastUtils;
  import org.apache.asterix.om.types.ATypeTag;
  import org.apache.asterix.om.types.BuiltinType;
  import org.apache.asterix.om.types.IAType;
  import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
  import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
  import org.apache.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
  
  public abstract class ListConstructorTypeComputer implements IResultTypeComputer {
  
      protected ListConstructorTypeComputer() {
      }
  
      @Override
      public IAType computeType(ILogicalExpression expression, IVariableTypeEnvironment env,
              IMetadataProvider<?, ?> metadataProvider) throws AlgebricksException {
          AbstractFunctionCallExpression f = (AbstractFunctionCallExpression) expression;
  
          /**
           * if type has been top-down propagated, use the enforced type
           */
          IAType reqType = TypeCastUtils.getRequiredType(f);
          if (reqType != null) {
              return reqType;
          }
          final IAType currentType = computeContentType(env, f);
          return getListType(currentType == null ? BuiltinType.ANY : currentType);
      }
  
      private IAType computeContentType(IVariableTypeEnvironment env, AbstractFunctionCallExpression f)
              throws AlgebricksException {
          IAType currentType = null;
          for (int k = 0; k < f.getArguments().size(); k++) {
              IAType type = (IAType) env.getType(f.getArguments().get(k).getValue());
              if (type.getTypeTag() == ATypeTag.UNION || (currentType != null && !currentType.equals(type))) {
                  return null;
              }
              currentType = type;
          }
          return currentType;
      }
  
      protected abstract IAType getListType(IAType itemType);
  
  }
  