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.base;
  
  import org.apache.asterix.om.typecomputer.impl.TypeComputeUtils;
  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.functions.FunctionIdentifier;
  import org.apache.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
  import org.apache.hyracks.api.exceptions.SourceLocation;
  
  /**
   * This abstract class takes care of the handling of optional types.
   * If a subclass follows the MISSING-in-MISSING-out and NULL-in-NULL-out semantics,
   * then it only needs to think of non-optional types and this abstract class
   * will strip the input types and wrap the output type.
   */
  public abstract class AbstractResultTypeComputer implements IResultTypeComputer {
  
      @Override
      public IAType computeType(ILogicalExpression expression, IVariableTypeEnvironment env,
              IMetadataProvider<?, ?> metadataProvider) throws AlgebricksException {
          AbstractFunctionCallExpression functionCallExpression = (AbstractFunctionCallExpression) expression;
          FunctionIdentifier funcId = functionCallExpression.getFunctionIdentifier();
          return TypeComputeUtils.resolveResultType(expression, env,
                  (index, type, sourceLoc) -> checkArgType(funcId, index, type, sourceLoc), this::getResultType,
                  propagateNullAndMissing());
      }
  
      /**
       * Checks whether an input type violates the requirement.
       *
       * @param argIndex,
       *            the index of the argument to consider.
       * @param type,
       *            the type of the input argument.
       * @param funcId
       *            the function identifier.
       * @param sourceLoc
       *            the source location
       * @throws AlgebricksException
       */
      protected void checkArgType(FunctionIdentifier funcId, int argIndex, IAType type, SourceLocation sourceLoc)
              throws AlgebricksException {
      }
  
      /**
       * Returns the result type without considering optional types.
       *
       * @param expr
       *            the expression under consideration.
       * @param strippedInputTypes,
       *            the stripped input types. When the function propagates null & missing, they can be any type except
       *            null, missing, and union.
       * @return the result type without considering optional types.
       * @throws AlgebricksException
       */
      protected abstract IAType getResultType(ILogicalExpression expr, IAType... strippedInputTypes)
              throws AlgebricksException;
  
      /**
       * Whether the expression follows MISSING-in-MISSING-out and NULL-in-NULL-out semantics
       * @return said value
       */
      protected boolean propagateNullAndMissing() {
          return true;
      }
  }
  