ceph/src/seastar/include/seastar/util/function_input_iterator.hh

   1 /*
   2  * This file is open source software, licensed to you under the terms
   3  * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
   4  * distributed with this work for additional information regarding copyright
   5  * ownership.  You may not use this file except in compliance with the License.
   6  *
   7  * 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.
  17  */
  18 /*
  19  * Copyright (C) 2014 Cloudius Systems, Ltd.
  20  */
  21
  22 #pragma once
  23
  24 namespace seastar {
  25
  26 template <typename Function, typename State>
  27 struct function_input_iterator {
  28     Function _func;
  29     State _state;
  30 public:
  31     function_input_iterator(Function func, State state)
  32         : _func(func), _state(state) {
  33     }
  34     function_input_iterator(const function_input_iterator&) = default;
  35     function_input_iterator(function_input_iterator&&) = default;
  36     function_input_iterator& operator=(const function_input_iterator&) = default;
  37     function_input_iterator& operator=(function_input_iterator&&) = default;
  38     auto operator*() const {
  39         return _func();
  40     }
  41     function_input_iterator& operator++() {
  42         ++_state;
  43         return *this;
  44     }
  45     function_input_iterator operator++(int) {
  46         function_input_iterator ret{*this};
  47         ++_state;
  48         return ret;
  49     }
  50     bool operator==(const function_input_iterator& x) const {
  51         return _state == x._state;
  52     }
  53     bool operator!=(const function_input_iterator& x) const {
  54         return !operator==(x);
  55     }
  56 };
  57
  58 template <typename Function, typename State>
  59 inline
  60 function_input_iterator<Function, State>
  61 make_function_input_iterator(Function func, State state) {
  62     return function_input_iterator<Function, State>(func, state);
  63 }
  64
  65 template <typename Function, typename State>
  66 inline
  67 function_input_iterator<Function, State>
  68 make_function_input_iterator(Function&& func) {
  69     return function_input_iterator<Function, State>(func, State{});
  70 }
  71
  72 }