ceph/src/arrow/cpp/src/arrow/util/print.h

   1 // Licensed to the Apache Software Foundation (ASF) under one
   2 // or more contributor license agreements.  See the NOTICE file
   3 // distributed with this work for additional information
   4 // regarding copyright ownership.  The ASF licenses this file
   5 // to you under the Apache License, Version 2.0 (the
   6 // "License"); you may not use this file except in compliance
   7 // with the License.  You may obtain a copy of the License at
   8 //
   9 //   http://www.apache.org/licenses/LICENSE-2.0
  10 //
  11 // Unless required by applicable law or agreed to in writing,
  12 // software distributed under the License is distributed on an
  13 // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  14 // KIND, either express or implied.  See the License for the
  15 // specific language governing permissions and limitations
  16 // under the License. template <typename T>
  17
  18 #pragma once
  19
  20 #include <tuple>
  21
  22 namespace arrow {
  23 namespace internal {
  24
  25 namespace detail {
  26
  27 template <typename OStream, typename Tuple, size_t N>
  28 struct TuplePrinter {
  29   static void Print(OStream* os, const Tuple& t) {
  30     TuplePrinter<OStream, Tuple, N - 1>::Print(os, t);
  31     *os << std::get<N - 1>(t);
  32   }
  33 };
  34
  35 template <typename OStream, typename Tuple>
  36 struct TuplePrinter<OStream, Tuple, 0> {
  37   static void Print(OStream* os, const Tuple& t) {}
  38 };
  39
  40 }  // namespace detail
  41
  42 // Print elements from a tuple to a stream, in order.
  43 // Typical use is to pack a bunch of existing values with std::forward_as_tuple()
  44 // before passing it to this function.
  45 template <typename OStream, typename... Args>
  46 void PrintTuple(OStream* os, const std::tuple<Args&...>& tup) {
  47   detail::TuplePrinter<OStream, std::tuple<Args&...>, sizeof...(Args)>::Print(os, tup);
  48 }
  49
  50 }  // namespace internal
  51 }  // namespace arrow