The Battle for Wesnoth  1.17.0-dev
formatter.hpp
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1 /*
2  Copyright (C) 2003 - 2021
3  by David White <dave@whitevine.net>
4  Part of the Battle for Wesnoth Project https://www.wesnoth.org/
5 
6  This program is free software; you can redistribute it and/or modify
7  it under the terms of the GNU General Public License as published by
8  the Free Software Foundation; either version 2 of the License, or
9  (at your option) any later version.
10  This program is distributed in the hope that it will be useful,
11  but WITHOUT ANY WARRANTY.
12 
13  See the COPYING file for more details.
14 */
15 
16 #pragma once
17 
18 #include <sstream>
19 #include <utility>
20 
21 /**
22  * std::ostringstream wrapper.
23  *
24  * ostringstream's operator<< doesn't return a ostringstream&. It returns an
25  * ostream& instead. This is unfortunate, because it means that you can't do
26  * something like this: (ostringstream() << n).str() to convert an integer to a
27  * string, all in one line instead you have to use this far more tedious
28  * approach:
29  * ostringstream s;
30  * s << n;
31  * s.str();
32  * This class corrects this shortcoming, allowing something like this:
33  * string result = (formatter() << "blah " << n << x << " blah").str();
34  *
35  * Actually, due to the ref qualified versions below, you can get away with this
36  *
37  * string result = formatter() << "blah " << n << x << " blah";
38  */
39 class formatter
40 {
41 public:
43  : stream_()
44  {
45  }
46 
47  template<typename T>
48  formatter& operator<<(const T& o) &
49  {
50  stream_ << o;
51  return *this;
52  }
53 
54  template<typename T>
55  formatter&& operator<<(const T& o) &&
56  {
57  stream_ << o;
58  return std::move(*this);
59  }
60 
61  std::string str() const
62  {
63  return stream_.str();
64  }
65 
66  // Implicit x-value conversion to string
67  operator std::string() const &&
68  {
69  return stream_.str();
70  }
71 
72  // Support manipulators
73  formatter& operator<<(std::ostream&(*fn)(std::ostream&)) &
74  {
75  fn(stream_);
76  return *this;
77  }
78 
79  formatter&& operator<<(std::ostream&(*fn)(std::ostream&)) &&
80  {
81  fn(stream_);
82  return std::move(*this);
83  }
84 
85  formatter& operator<<(std::ios_base&(*fn)(std::ios_base&)) &
86  {
87  fn(stream_);
88  return *this;
89  }
90 
91  formatter&& operator<<(std::ios_base&(*fn)(std::ios_base&)) &&
92  {
93  fn(stream_);
94  return std::move(*this);
95  }
96 
97 private:
98  std::ostringstream stream_;
99 };
formatter && operator<<(std::ios_base &(*fn)(std::ios_base &)) &&
Definition: formatter.hpp:91
std::ostringstream wrapper.
Definition: formatter.hpp:39
formatter & operator<<(const T &o) &
Definition: formatter.hpp:48
formatter && operator<<(const T &o) &&
Definition: formatter.hpp:55
std::ostringstream stream_
Definition: formatter.hpp:98
formatter && operator<<(std::ostream &(*fn)(std::ostream &)) &&
Definition: formatter.hpp:79
std::string str() const
Definition: formatter.hpp:61
formatter & operator<<(std::ostream &(*fn)(std::ostream &)) &
Definition: formatter.hpp:73
formatter & operator<<(std::ios_base &(*fn)(std::ios_base &)) &
Definition: formatter.hpp:85