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 static org.apache.asterix.om.types.BuiltinType.ANULL;
  
  import java.util.ArrayList;
  import java.util.List;
  
  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.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 class SwitchCaseComputer implements IResultTypeComputer {
  
      public static final IResultTypeComputer INSTANCE = new SwitchCaseComputer();
  
      private SwitchCaseComputer() {
      }
  
      @Override
      public IAType computeType(ILogicalExpression expression, IVariableTypeEnvironment env,
              IMetadataProvider<?, ?> metadataProvider) throws AlgebricksException {
          AbstractFunctionCallExpression fce = (AbstractFunctionCallExpression) expression;
          String funcName = fce.getFunctionIdentifier().getName();
  
          int argSize = fce.getArguments().size();
          if (argSize < 3) {
              throw new CompilationException(ErrorCode.COMPILATION_INVALID_PARAMETER_NUMBER, fce.getSourceLocation(),
                      funcName, argSize);
          }
          List<IAType> types = new ArrayList<>();
          // Collects different branches' return types.
          // The last return expression is from the ELSE branch and it is optional.
          for (int argIndex = 2; argIndex < argSize; argIndex += (argIndex + 2 == argSize) ? 1 : 2) {
              IAType type = (IAType) env.getType(fce.getArguments().get(argIndex).getValue());
              types.add(type);
          }
          // TODO(ali): investigate if needed for CASE. assumption seems to be that CASE is always rewritten with default
          if (addDefaultNull(argSize)) {
              types.add(ANULL);
          }
          return TypeResolverUtil.resolve(types);
      }
  
      private boolean addDefaultNull(int argSize) {
          // null is the default value for odd arg size (e.g. fun(cond_exp, exp1, res1))
          return argSize % 2 != 0;
      }
  }
  