text: // 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.
  
  #include "arrow/util/time.h"
  #include "arrow/util/checked_cast.h"
  
  namespace arrow {
  namespace util {
  
  Result<int64_t> ConvertTimestampValue(const std::shared_ptr<DataType>& in,
                                        const std::shared_ptr<DataType>& out,
                                        int64_t value) {
    auto from = internal::checked_pointer_cast<TimestampType>(in)->unit();
    auto to = internal::checked_pointer_cast<TimestampType>(out)->unit();
  
    auto op_factor =
        util::kTimestampConversionTable[static_cast<int>(from)][static_cast<int>(to)];
  
    auto op = op_factor.first;
    auto factor = op_factor.second;
    switch (op) {
      case MULTIPLY:
        return value * factor;
      case DIVIDE:
        return value / factor;
    }
  
    // unreachable...
    return 0;
  }
  
  }  // namespace util
  }  // namespace arrow
  