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Add default_ok and default_err.

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This commit is contained in:
Nerijus Arlauskas 2016-07-07 14:48:25 +03:00
parent 8c11104417
commit 8b0e3f0e13
1 changed files with 27 additions and 3 deletions
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30
src/maybe/result.hpp
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@ -114,6 +114,12 @@ namespace maybe {
clear();
};
/** helper constructor for default ok value */
constexpr static result<T, E> default_ok() noexcept
{
return result<T, E>(T(), internal::Placeholder{});
}
/** helper constructor for ok value */
constexpr static result<T, E> ok(T&& value) noexcept
{
@ -126,6 +132,12 @@ namespace maybe {
return result<T, E>(value, internal::Placeholder{});
}
/** helper constructor for default err value */
constexpr static result<T, E> default_err() noexcept
{
return result<T, E>(internal::Placeholder{}, E());
}
/** helper constructor for err value */
constexpr static result<T, E> err(E&& err) noexcept
{
@ -196,7 +208,8 @@ namespace maybe {
}
/**
* Maps a result<T, E> to result<U, E> (where U is return value of F(T)) by applying a function F to a
* Maps a result<T, E> to result<U, E> (where U is return value of F(T)) by applying a
* function F to a
* contained ok value, leaving an err value untouched.
*
* This function can be used to compose the results of two functions.
@ -208,7 +221,8 @@ namespace maybe {
constexpr auto map(F f) noexcept -> maybe::result<typename std::result_of<F(T)>::type, E>;
/**
* Maps a result<T, E> to result<T, U> (where U is return value of F(E)) by applying a function to a
* Maps a result<T, E> to result<T, U> (where U is return value of F(E)) by applying a
* function to a
* contained err value, leaving an ok value untouched.
*
* This function can be used to pass through a successful result while changing an error.
@ -217,7 +231,8 @@ namespace maybe {
* @return maybe::result<T, U>
*/
template <typename F>
constexpr auto map_err(F f) noexcept -> maybe::result<T, typename std::result_of<F(E)>::type>;
constexpr auto map_err(F f) noexcept
-> maybe::result<T, typename std::result_of<F(E)>::type>;
/**
* Calls op if the result is ok, otherwise returns the err value of self.
@ -230,6 +245,15 @@ namespace maybe {
template <typename F>
constexpr auto and_then(F op) noexcept -> typename std::result_of<F(T)>::type;
template <typename R>
constexpr auto into_err() noexcept -> R
{
if (is_err()) {
return R::err(std::forward<E>(err_value()));
}
return R::default_ok();
};
private:
constexpr void copy_from(const result<T, E>& other) noexcept;
constexpr void set_from(result<T, E>& other) noexcept;