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.common.exceptions.CompilationException;
  import org.apache.asterix.common.exceptions.ErrorCode;
  import org.apache.asterix.dataflow.data.common.TypeResolverUtil;
  import org.apache.asterix.om.typecomputer.base.IResultTypeComputer;
  import org.apache.asterix.om.types.ATypeTag;
  import org.apache.asterix.om.types.AUnionType;
  import org.apache.asterix.om.types.BuiltinType;
  import org.apache.asterix.om.types.IAType;
  import org.apache.commons.lang3.mutable.Mutable;
  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;
  import org.apache.hyracks.api.exceptions.SourceLocation;
  
  abstract class AbstractIfMissingOrNullTypeComputer implements IResultTypeComputer {
      @Override
      public IAType computeType(ILogicalExpression expression, IVariableTypeEnvironment env,
              IMetadataProvider<?, ?> metadataProvider) throws AlgebricksException {
          AbstractFunctionCallExpression fce = (AbstractFunctionCallExpression) expression;
          SourceLocation sourceLoc = fce.getSourceLocation();
          IAType outPrimeType = null;
          ATypeTag outQuantifier = null; // could be 'missing' or 'null'
  
          for (Mutable<ILogicalExpression> argRef : fce.getArguments()) {
              ILogicalExpression arg = argRef.getValue();
              IAType argType = (IAType) env.getType(arg);
              ATypeTag argTypeTag = argType.getTypeTag();
  
              if (equalsIfType(argTypeTag)) {
                  continue;
              }
  
              if (argTypeTag == ATypeTag.UNION) {
                  AUnionType unionType = (AUnionType) argType;
                  if (intersectsIfType(unionType)) {
                      IAType primeType = getOutputPrimeType(unionType);
                      outPrimeType = outPrimeType == null ? primeType : TypeResolverUtil.resolve(outPrimeType, primeType);
                      if (outQuantifier == null) {
                          outQuantifier = getOutputQuantifier(unionType);
                      }
                  } else {
                      // no intersection
                      if (outPrimeType == null) {
                          return argType;
                      } else {
                          IAType primeType = getOutputPrimeType(unionType);
                          ATypeTag quantifier = outQuantifier != null ? outQuantifier : getOutputQuantifier(unionType);
                          return createOutputType(TypeResolverUtil.resolve(outPrimeType, primeType), quantifier,
                                  sourceLoc);
                      }
                  }
              } else {
                  // ANY or no intersection
                  return outPrimeType == null ? argType
                          : createOutputType(TypeResolverUtil.resolve(outPrimeType, argType), outQuantifier, sourceLoc);
              }
          }
  
          if (outPrimeType == null) {
              return BuiltinType.ANULL;
          }
          IAType outType = createOutputType(outPrimeType, ATypeTag.NULL, sourceLoc);
          if (outQuantifier == ATypeTag.MISSING) {
              outType = createOutputType(outType, ATypeTag.MISSING, sourceLoc);
          }
          return outType;
      }
  
      protected abstract boolean equalsIfType(ATypeTag typeTag);
  
      protected abstract boolean intersectsIfType(AUnionType type);
  
      protected abstract ATypeTag getOutputQuantifier(AUnionType type);
  
      private IAType getOutputPrimeType(AUnionType type) {
          return type.getActualType();
      }
  
      private IAType createOutputType(IAType primeType, ATypeTag quantifier, SourceLocation sourceLoc)
              throws CompilationException {
          if (quantifier == null || primeType.getTypeTag() == ATypeTag.ANY) {
              return primeType;
          }
          switch (quantifier) {
              case MISSING:
                  return AUnionType.createMissableType(primeType);
              case NULL:
                  return AUnionType.createNullableType(primeType, null);
              default:
                  throw new CompilationException(ErrorCode.COMPILATION_ILLEGAL_STATE, sourceLoc,
                          "Unexpected quantifier: " + quantifier);
          }
      }
  }
  