Bitcoin Core  26.99.0
P2P Digital Currency
result.h
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1 // Copyright (c) 2022 The Bitcoin Core developers
2 // Distributed under the MIT software license, see the accompanying
3 // file COPYING or https://www.opensource.org/licenses/mit-license.php.
4 
5 #ifndef BITCOIN_UTIL_RESULT_H
6 #define BITCOIN_UTIL_RESULT_H
7 
8 #include <attributes.h>
9 #include <util/translation.h>
10 
11 #include <variant>
12 
13 namespace util {
14 
15 struct Error {
17 };
18 
34 template <class M>
35 class Result
36 {
37 private:
38  using T = std::conditional_t<std::is_same_v<M, void>, std::monostate, M>;
39 
40  std::variant<bilingual_str, T> m_variant;
41 
42  template <typename FT>
43  friend bilingual_str ErrorString(const Result<FT>& result);
44 
45 public:
46  Result() : m_variant{std::in_place_index_t<1>{}, std::monostate{}} {} // constructor for void
47  Result(T obj) : m_variant{std::in_place_index_t<1>{}, std::move(obj)} {}
48  Result(Error error) : m_variant{std::in_place_index_t<0>{}, std::move(error.message)} {}
49 
52  bool has_value() const noexcept { return m_variant.index() == 1; }
53  const T& value() const LIFETIMEBOUND
54  {
55  assert(has_value());
56  return std::get<1>(m_variant);
57  }
59  {
60  assert(has_value());
61  return std::get<1>(m_variant);
62  }
63  template <class U>
64  T value_or(U&& default_value) const&
65  {
66  return has_value() ? value() : std::forward<U>(default_value);
67  }
68  template <class U>
69  T value_or(U&& default_value) &&
70  {
71  return has_value() ? std::move(value()) : std::forward<U>(default_value);
72  }
73  explicit operator bool() const noexcept { return has_value(); }
74  const T* operator->() const LIFETIMEBOUND { return &value(); }
75  const T& operator*() const LIFETIMEBOUND { return value(); }
76  T* operator->() LIFETIMEBOUND { return &value(); }
77  T& operator*() LIFETIMEBOUND { return value(); }
78 };
79 
80 template <typename T>
82 {
83  return result ? bilingual_str{} : std::get<0>(result.m_variant);
84 }
85 } // namespace util
86 
87 #endif // BITCOIN_UTIL_RESULT_H
#define LIFETIMEBOUND
Definition: attributes.h:16
T value_or(U &&default_value) const &
Definition: result.h:64
const T & value() const LIFETIMEBOUND
Definition: result.h:53
T & operator*() LIFETIMEBOUND
Definition: result.h:77
Result(Error error)
Definition: result.h:48
T & value() LIFETIMEBOUND
Definition: result.h:58
bool has_value() const noexcept
std::optional methods, so functions returning optional<T> can change to return Result<T> with minimal...
Definition: result.h:52
T * operator->() LIFETIMEBOUND
Definition: result.h:76
const T & operator*() const LIFETIMEBOUND
Definition: result.h:75
T value_or(U &&default_value) &&
Definition: result.h:69
Result(T obj)
Definition: result.h:47
friend bilingual_str ErrorString(const Result< FT > &result)
std::conditional_t< std::is_same_v< M, void >, std::monostate, M > T
Definition: result.h:38
std::variant< bilingual_str, T > m_variant
Definition: result.h:40
const T * operator->() const LIFETIMEBOUND
Definition: result.h:74
bool error(const char *fmt, const Args &... args)
Definition: logging.h:267
bilingual_str ErrorString(const Result< T > &result)
Definition: result.h:81
Bilingual messages:
Definition: translation.h:18
bilingual_str message
Definition: result.h:16
assert(!tx.IsCoinBase())