expected.h

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/******************************************************************************
The MIT License(MIT)
 
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
 
Copyright(c) 2022 John Wellbelove
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files(the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
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The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
 
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******************************************************************************/
 
#ifndef ETL_EXPECTED_INCLUDED
#define ETL_EXPECTED_INCLUDED
 
#include "platform.h"
#include "exception.h"
#include "error_handler.h"
#include "utility.h"
#include "variant.h"
 
namespace etl
{
  //***************************************************************************
  //***************************************************************************
  class expected_exception : public etl::exception
  {
  public:
 
    expected_exception(string_type reason_, string_type file_name_, numeric_type line_number_)
      : exception(reason_, file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  template <typename TError>
  class expected_invalid;
 
  //*******************************************
  template<>
  class expected_invalid<void> : public etl::expected_exception
  {
  public:
 
    expected_invalid(string_type file_name_, numeric_type line_number_)
      : expected_exception(ETL_ERROR_TEXT("expected:invalid", ETL_EXPECTED_FILE_ID"A"), file_name_, line_number_)
    {
    }
  };
 
  //*******************************************
  template <typename TError>
  class expected_invalid : etl::expected_invalid<void>
  {
  public:
 
    expected_invalid(string_type file_name_, numeric_type line_number_)
      : expected_invalid<void>(file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  template <typename TError>
  class unexpected
  {
  public:
 
    typedef TError error_type;
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR unexpected(const unexpected& other)
      : error_value(other.error_value)
    {
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR unexpected(unexpected&& other)
      : error_value(etl::move(other.error_value))
    {
    }
#endif
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR explicit unexpected(const TError& e)
      : error_value(e)
    {
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR explicit unexpected(TError&& e)
      : error_value(etl::forward<TError>(e))
    {
    }
 
    //*******************************************
    //*******************************************
    template <typename... Args >
    ETL_CONSTEXPR explicit unexpected(etl::in_place_t, Args&&... args)
      : error_value(etl::forward<Args>(args)...)
    {
    }
#endif
 
#if ETL_HAS_INITIALIZER_LIST
    //*******************************************
    //*******************************************
    template <typename U, typename... Args>
    ETL_CONSTEXPR explicit unexpected(etl::in_place_t, std::initializer_list<U> init, Args&&... args)
      : error_value(init, etl::forward<Args>(args)...)
    {
    }
#endif
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14
      etl::unexpected<TError>& operator =(const etl::unexpected<TError>& rhs)
    {
      ETL_STATIC_ASSERT(etl::is_copy_constructible<TError>::value, "Error not copy assignable");
 
      error_value = rhs.error_value;
      return *this;
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14
      etl::unexpected<TError>& operator =(etl::unexpected<TError>&& rhs)
    {
      ETL_STATIC_ASSERT(etl::is_move_constructible<TError>::value, "Error not move assignable");
 
      error_value = etl::move(rhs.error_value);
      return *this;
    }
#endif
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 TError& error()& ETL_NOEXCEPT
    {
      return error_value;
    }
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 const TError& error() const& ETL_NOEXCEPT
    {
      return error_value;
    }
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 TError&& error()&& ETL_NOEXCEPT
    {
      return etl::move(error_value);
    }
 
    //*******************************************
    //*******************************************    
    ETL_CONSTEXPR14 TError&& error() const&& ETL_NOEXCEPT
    {
      return etl::move(error_value);
    }
#else
    //*******************************************
    //*******************************************
    const TError& error() const
    {
      return error_value;
    }
#endif
 
    //*******************************************
    //*******************************************
    void swap(etl::unexpected<TError>& other)
    {
      using ETL_OR_STD::swap;
 
      swap(error_value, other.error_value);
    }
 
  private:
 
    TError error_value;
  };
 
  //*****************************************************************************
  //*****************************************************************************
  struct unexpect_t
  {
    ETL_CONSTEXPR14 explicit unexpect_t()
    {
    }
  };
 
#if ETL_USING_CPP17
  inline ETL_CONSTEXPR unexpect_t unexpect{};
#else
  static const unexpect_t unexpect;
#endif
 
  //*****************************************************************************
  //*****************************************************************************
  template <typename TValue, typename TError>
  class expected
  {
  public:
 
    typedef etl::expected<TValue, TError> this_type;
    typedef TValue                        value_type;
    typedef TError                        error_type;
    typedef etl::unexpected<TError>       unexpected_type;
 
#if ETL_USING_CPP11
    template <typename U>
    using rebind = expected<U, TError>;
#endif
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 expected() ETL_NOEXCEPT
      : storage(etl::in_place_index_t<Value_Type>(), value_type())
    {
    }
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 expected(const value_type& value_) ETL_NOEXCEPT
      : storage(etl::in_place_index_t<Value_Type>(), value_)
    {
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 expected(value_type&& value_) ETL_NOEXCEPT
      : storage(etl::in_place_index_t<Value_Type>(), etl::move(value_))
    {
    }
#endif
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 expected(const expected& other) ETL_NOEXCEPT
      : storage(other.storage)
    {
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 expected(expected&& other) ETL_NOEXCEPT
      : storage(etl::move(other.storage))
    {
    }
#endif
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    template <typename G, typename etl::enable_if<!etl::is_convertible<const G&, TError>::value, bool>::type = false>
    ETL_CONSTEXPR14 explicit expected(const etl::unexpected<G>& ue)
      : storage(etl::in_place_index_t<Error_Type>(), ue.error())
    {
    }
 
    template <typename G, typename etl::enable_if<etl::is_convertible<const G&, TError>::value, bool>::type = false>
    ETL_CONSTEXPR14 expected(const etl::unexpected<G>& ue)
      : storage(etl::in_place_index_t<Error_Type>(), ue.error())
    {
    }
#else
    template <typename G>
    explicit expected(const etl::unexpected<G>& ue)
      : storage(etl::in_place_index_t<Error_Type>(), ue.error())
    {
    }
#endif
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    template <typename G, typename etl::enable_if<!etl::is_convertible<const G&, TError>::value, bool>::type = false>
    ETL_CONSTEXPR14 explicit expected(etl::unexpected<G>&& ue)
      : storage(etl::in_place_index_t<Error_Type>(), etl::move(ue.error()))
    {
    }
 
    template <typename G, typename etl::enable_if<etl::is_convertible<const G&, TError>::value, bool>::type = false>
    ETL_CONSTEXPR14 expected(etl::unexpected<G>&& ue)
      : storage(etl::in_place_index_t<Error_Type>(), etl::move(ue.error()))
    {
    }
#endif
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 explicit expected(etl::in_place_t) ETL_NOEXCEPT
      : storage(value_type())
    {
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    template <typename... Args>
    ETL_CONSTEXPR14 explicit expected(etl::in_place_t, Args&&... args)
      : storage(etl::forward<Args>(args)...)
    {
    }
 
    //*******************************************
    //*******************************************
    template <typename U, typename... Args>
    ETL_CONSTEXPR14 explicit expected(etl::in_place_t, std::initializer_list<U> il, Args&&... args)
      : storage(il, etl::forward<Args>(args)...)
    {
    }
 
    //*******************************************
    //*******************************************
    template <typename... Args>
    ETL_CONSTEXPR14 explicit expected(etl::unexpect_t, Args&&... args)
      : storage(error_type(etl::forward<Args>(args)...))
    {
    }
 
#if ETL_HAS_INITIALIZER_LIST
    //*******************************************
    //*******************************************
    template <typename U, typename... Args>
    ETL_CONSTEXPR14 explicit expected(etl::unexpect_t, std::initializer_list<U> il, Args&&... args)
      : storage(error_type(il, etl::forward<Args>(args)...))
    {
    }
#endif
#endif
 
    //*******************************************
    //*******************************************
    this_type& operator =(const this_type& other)
    {
      ETL_STATIC_ASSERT(etl::is_copy_constructible<TValue>::value && etl::is_copy_constructible<TError>::value, "Not copy assignable");
 
      storage = other.storage;
 
      return *this;
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    this_type& operator =(this_type&& other)
    {
      ETL_STATIC_ASSERT(etl::is_move_constructible<TValue>::value && etl::is_move_constructible<TError>::value, "Not move assignable");
 
      storage = etl::move(other.storage);
      return *this;
    }
#endif
 
    //*******************************************
    //*******************************************
    expected& operator =(const value_type& value)
    {
      ETL_STATIC_ASSERT(etl::is_copy_constructible<TValue>::value, "Value not copy assignable");
 
      storage = value;
      return *this;
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    expected& operator =(value_type&& value)
    {
      ETL_STATIC_ASSERT(etl::is_move_constructible<TValue>::value, "Value not move assignable");
 
      storage = etl::move(value);
      return *this;
    }
#endif
 
    //*******************************************
    //*******************************************
    expected& operator =(const unexpected_type& ue)
    {
      ETL_STATIC_ASSERT(etl::is_copy_constructible<TError>::value, "Error not copy assignable");
 
      storage = ue.error();
 
      return *this;
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    expected& operator =(unexpected_type&& ue)
    {
      ETL_STATIC_ASSERT(etl::is_move_constructible<TError>::value, "Error not move assignable");
 
      storage = etl::move(ue.error());
 
      return *this;
    }
#endif
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 value_type& value()&
    {
      return etl::get<Value_Type>(storage);
    }
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 const value_type& value() const&
    {
      return etl::get<Value_Type>(storage);
    }
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 value_type&& value()&&
    {
      return etl::move(etl::get<Value_Type>(storage));
    }
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14 const value_type&& value() const&&
    {
      return etl::move(etl::get<Value_Type>(storage));
    }
#else
    //*******************************************
    //*******************************************
    value_type& value() const
    {
      return etl::get<Value_Type>(storage);
    }
#endif
 
    //*******************************************
    //*******************************************
    ETL_NODISCARD
    ETL_CONSTEXPR14
    bool has_value() const
    {
      return (storage.index() == Value_Type);
    }
 
    //*******************************************
    //*******************************************
    ETL_NODISCARD
    ETL_CONSTEXPR14
    operator bool() const
    {
      return has_value();
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    template <typename U>
    ETL_NODISCARD
    ETL_CONSTEXPR14
    etl::enable_if_t<etl::is_convertible<U, value_type>::value, value_type>
      value_or(U&& default_value) const&
    {
      if (has_value())
      {
        return value();
      }
      else
      {
        return static_cast<value_type>(etl::forward<U>(default_value));
      }
    }
 
    //*******************************************
    //*******************************************
    template <typename U>
    ETL_NODISCARD
    ETL_CONSTEXPR14
    etl::enable_if_t<etl::is_convertible<U, value_type>::value, value_type>
      value_or(U&& default_value)&&
    {
      if (has_value())
      {
        return etl::move(value());
      }
      else
      {
        return static_cast<value_type>(etl::forward<U>(default_value));
      }
    }
 
    //*******************************************
    //*******************************************
    ETL_NODISCARD
    ETL_CONSTEXPR14
    error_type& error()& ETL_NOEXCEPT
    {
      return etl::get<Error_Type>(storage);
    }
 
    //*******************************************
    //*******************************************
    ETL_NODISCARD
    ETL_CONSTEXPR14
    const error_type& error() const& ETL_NOEXCEPT
    {
      return etl::get<Error_Type>(storage);
    }
 
    //*******************************************
    //*******************************************
    ETL_NODISCARD
    ETL_CONSTEXPR14
    error_type&& error()&& ETL_NOEXCEPT
    {
      return etl::move(etl::get<Error_Type>(storage));
    }
 
    //*******************************************
    //*******************************************
    ETL_NODISCARD
    ETL_CONSTEXPR14
    const error_type&& error() const&& ETL_NOEXCEPT
    {
      return etl::move(etl::get<Error_Type>(storage));
    }
 
    //*******************************************
    //*******************************************
    template <typename... Args>
    ETL_CONSTEXPR14 value_type& emplace(Args&&... args) ETL_NOEXCEPT
    {
      storage.emplace(etl::forward<Args>(args)...);
    }
 
    //*******************************************
    //*******************************************
    template <typename U, typename... Args>
    ETL_CONSTEXPR14 value_type& emplace(std::initializer_list<U>& il, Args&&... args) ETL_NOEXCEPT
    {
      storage.emplace(il, etl::forward<Args>(args)...);
    }
#else
    //*******************************************
    //*******************************************
    template <typename U>
    value_type value_or(const U& default_value) const
    {
      if (has_value())
      {
        return value();
      }
      else
      {
        return default_value;
      }
    }
 
    //*******************************************
    //*******************************************
    error_type& error() const
    {
      return etl::get<Error_Type>(storage);
    }
#endif
 
    //*******************************************
    //*******************************************
    value_type* operator ->()
    {
#if ETL_IS_DEBUG_BUILD
      ETL_ASSERT(storage.index() == Value_Type, ETL_ERROR(expected_invalid<TError>));
#endif
 
      return etl::addressof(etl::get<value_type>(storage));
    }
 
    //*******************************************
    //*******************************************
    const value_type* operator ->() const
    {
#if ETL_IS_DEBUG_BUILD
      ETL_ASSERT(storage.index() == Value_Type, ETL_ERROR(expected_invalid<TError>));
#endif
 
      return etl::addressof(etl::get<value_type>(storage));
    }
 
    //*******************************************
    //*******************************************
    value_type& operator *() ETL_LVALUE_REF_QUALIFIER
    {
#if ETL_IS_DEBUG_BUILD
      ETL_ASSERT(storage.index() == Value_Type, ETL_ERROR(expected_invalid<TError>));
#endif
 
      return etl::get<value_type>(storage);
    }
 
    //*******************************************
    //*******************************************
    const value_type& operator *() const ETL_LVALUE_REF_QUALIFIER
    {
#if ETL_IS_DEBUG_BUILD
      ETL_ASSERT(storage.index() == Value_Type, ETL_ERROR(expected_invalid<TError>));
#endif
 
      return etl::get<value_type>(storage);
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    value_type&& operator *()&&
    {
#if ETL_IS_DEBUG_BUILD
      ETL_ASSERT(storage.index() == Value_Type, ETL_ERROR(expected_invalid<TError>));
#endif
 
      return etl::move(etl::get<value_type>(storage));
    }
 
    //*******************************************
    //*******************************************
    const value_type&& operator *() const&&
    {
#if ETL_IS_DEBUG_BUILD
      ETL_ASSERT(storage.index() == Value_Type, ETL_ERROR(expected_invalid<TError>));
#endif
 
      return etl::move(etl::get<value_type>(storage));
    }
#endif
 
  private:
 
    enum
    {
      Uninitialised,
      Value_Type,
      Error_Type
    };
 
    typedef etl::variant<etl::monostate, value_type, error_type> storage_type;
    storage_type storage;
  };
 
  //*****************************************************************************
  //*****************************************************************************
  template<typename TError>
  class expected<void, TError>
  {
  public:
 
    typedef etl::expected<void, TError> this_type;
    typedef void                        value_type;
    typedef TError                      error_type;
    typedef etl::unexpected<TError>     unexpected_type;
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14
      expected()
    {
    }
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14
      expected(const unexpected_type& ue_)
      : storage(ue_.error())
    {
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14
      expected(unexpected_type&& ue_)
      : storage(etl::move(ue_.error()))
    {
    }
#endif
 
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14
      expected(const this_type& other)
      : storage(other.storage)
    {
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    ETL_CONSTEXPR14
      expected(this_type&& other)
      : storage(etl::move(other.storage))
    {
    }
#endif
 
    //*******************************************
    //*******************************************
    this_type& operator =(const this_type& other)
    {
      ETL_STATIC_ASSERT(etl::is_copy_constructible<TError>::value, "Not copy assignable");
 
      storage = other.storage;
      return *this;
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    this_type& operator =(this_type&& other)
    {
      ETL_STATIC_ASSERT(etl::is_move_constructible<TError>::value, "Not move assignable");
 
      storage = etl::move(other.storage);
      return *this;
    }
#endif
 
    //*******************************************
    //*******************************************
    expected& operator =(const unexpected_type& ue)
    {
      ETL_STATIC_ASSERT(etl::is_copy_constructible<TError>::value, "Error not copy assignable");
 
      storage.template emplace<Error_Type>(ue.error());
      return *this;
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    expected& operator =(unexpected_type&& ue)
    {
      ETL_STATIC_ASSERT(etl::is_move_constructible<TError>::value, "Error not move assignable");
 
      storage.template emplace<Error_Type>(etl::move(ue.error()));
      return *this;
    }
#endif
 
    //*******************************************
    //*******************************************
    ETL_NODISCARD
      ETL_CONSTEXPR14
      bool has_value() const
    {
      return (storage.index() != Error_Type);
    }
 
    //*******************************************
    //*******************************************
    ETL_NODISCARD
      ETL_CONSTEXPR14
      operator bool() const
    {
      return has_value();
    }
 
#if ETL_USING_CPP11
    //*******************************************
    //*******************************************
    ETL_NODISCARD
      ETL_CONSTEXPR14
      error_type& error()& ETL_NOEXCEPT
    {
      return etl::get<Error_Type>(storage);
    }
 
    //*******************************************
    //*******************************************
    ETL_NODISCARD
      ETL_CONSTEXPR14
      const error_type& error() const& ETL_NOEXCEPT
    {
      return etl::get<Error_Type>(storage);
    }
 
    //*******************************************
    //*******************************************
    ETL_NODISCARD
      ETL_CONSTEXPR14
      error_type&& error() && ETL_NOEXCEPT
    {
      return etl::move(etl::get<Error_Type>(storage));
    }
 
    //*******************************************
    //*******************************************
    ETL_NODISCARD
      ETL_CONSTEXPR14
      const error_type&& error() const&& ETL_NOEXCEPT
    {
      return etl::move(etl::get<Error_Type>(storage));
    }
#else
    //*******************************************
    //*******************************************
    error_type& error() const
    {
      return etl::get<Error_Type>(storage);
    }
#endif
 
  private:
 
    enum
    {
      Uninitialised,
      Error_Type
    };
 
    etl::variant<etl::monostate, error_type> storage;
  };
}
 
//*******************************************
//*******************************************
template <typename TError>
ETL_CONSTEXPR14
bool operator ==(const etl::unexpected<TError>& lhs, const etl::unexpected<TError>& rhs)
{
  return lhs.error_value == rhs.error_value;
}
 
//*******************************************
//*******************************************
template <typename TError>
ETL_CONSTEXPR14
void swap(etl::unexpected<TError>& lhs, etl::unexpected<TError>& rhs)
{
  lhs.swap(rhs);
}
 
#endif