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.runtime.evaluators.functions;
  
  import org.apache.asterix.om.functions.BuiltinFunctions;
  import org.apache.asterix.om.functions.IFunctionDescriptorFactory;
  import org.apache.asterix.runtime.evaluators.base.AbstractScalarFunctionDynamicDescriptor;
  import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluator;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
  import org.apache.hyracks.api.context.IEvaluatorContext;
  import org.apache.hyracks.api.exceptions.HyracksDataException;
  import org.apache.hyracks.data.std.api.IPointable;
  import org.apache.hyracks.data.std.primitive.VoidPointable;
  import org.apache.hyracks.dataflow.common.data.accessors.IFrameTupleReference;
  
  public class SwitchCaseDescriptor extends AbstractScalarFunctionDynamicDescriptor {
  
      private static final long serialVersionUID = 1L;
      public static final IFunctionDescriptorFactory FACTORY = SwitchCaseDescriptor::new;
  
      @Override
      public FunctionIdentifier getIdentifier() {
          return BuiltinFunctions.SWITCH_CASE;
      }
  
      @Override
      public IScalarEvaluatorFactory createEvaluatorFactory(final IScalarEvaluatorFactory[] args) {
          return new IScalarEvaluatorFactory() {
              private static final long serialVersionUID = 1L;
  
              @Override
              public IScalarEvaluator createScalarEvaluator(final IEvaluatorContext ctx) throws HyracksDataException {
                  final IPointable condPtr = new VoidPointable();
                  final IPointable casePtr = new VoidPointable();
                  final IPointable argPtr = new VoidPointable();
  
                  final IScalarEvaluator[] evals = new IScalarEvaluator[args.length];
                  // condition
                  evals[0] = args[0].createScalarEvaluator(ctx);
                  // case value
                  for (int i = 1; i < evals.length - 1; i += 2) {
                      evals[i] = args[i].createScalarEvaluator(ctx);
                  }
                  // case expression
                  for (int i = 2; i < evals.length - 1; i += 2) {
                      evals[i] = args[i].createScalarEvaluator(ctx);
                  }
                  // default expression
                  evals[evals.length - 1] = args[evals.length - 1].createScalarEvaluator(ctx);
  
                  return new IScalarEvaluator() {
  
                      @Override
                      public void evaluate(IFrameTupleReference tuple, IPointable result) throws HyracksDataException {
                          int n = args.length;
                          evals[0].evaluate(tuple, condPtr);
                          for (int i = 1; i < n - 1; i += 2) {
                              evals[i].evaluate(tuple, casePtr);
                              if (equals(condPtr, casePtr)) {
                                  evals[i + 1].evaluate(tuple, argPtr);
                                  result.set(argPtr);
                                  return;
                              }
                          }
                          // the default case
                          evals[n - 1].evaluate(tuple, argPtr);
                          result.set(argPtr);
                      }
  
                      private boolean equals(IPointable out1, IPointable out2) {
                          if (out1.getLength() != out2.getLength()) {
                              return false;
                          }
                          byte[] data1 = out1.getByteArray();
                          byte[] data2 = out2.getByteArray();
                          for (int i = out1.getStartOffset(), j = out2.getStartOffset(), k = 0; k < out1
                                  .getLength(); ++i, ++j, ++k) {
                              if (data1[i] != data2[j]) {
                                  return false;
                              }
                          }
                          return true;
                      }
                  };
              }
          };
      }
  
  }
  