toml11/toml/result.hpp
ToruNiina 717f5929c2 feat: use detail::none_t instead of char
Although the error value from combinators currently does not have any
information, it can have an information because it is a char value. It
is better to use no-information-type explicitly to make it clear that
it does not have any information. So I added none_t in toml::detai and
use it in combinators and parsers as an error value from combinators.
2019-05-31 17:07:52 +09:00

718 lines
21 KiB
C++

// Copyright Toru Niina 2017.
// Distributed under the MIT License.
#ifndef TOML11_RESULT_HPP
#define TOML11_RESULT_HPP
#include "traits.hpp"
#include <type_traits>
#include <stdexcept>
#include <utility>
#include <new>
#include <string>
#include <sstream>
#include <cassert>
namespace toml
{
template<typename T>
struct success
{
using value_type = T;
value_type value;
explicit success(const value_type& v)
noexcept(std::is_nothrow_copy_constructible<value_type>::value)
: value(v)
{}
explicit success(value_type&& v)
noexcept(std::is_nothrow_move_constructible<value_type>::value)
: value(std::move(v))
{}
template<typename U>
explicit success(U&& v): value(std::forward<U>(v)) {}
template<typename U>
explicit success(const success<U>& v): value(v.value) {}
template<typename U>
explicit success(success<U>&& v): value(std::move(v.value)) {}
~success() = default;
success(const success&) = default;
success(success&&) = default;
success& operator=(const success&) = default;
success& operator=(success&&) = default;
};
template<typename T>
struct failure
{
using value_type = T;
value_type value;
explicit failure(const value_type& v)
noexcept(std::is_nothrow_copy_constructible<value_type>::value)
: value(v)
{}
explicit failure(value_type&& v)
noexcept(std::is_nothrow_move_constructible<value_type>::value)
: value(std::move(v))
{}
template<typename U>
explicit failure(U&& v): value(std::forward<U>(v)) {}
template<typename U>
explicit failure(const failure<U>& v): value(v.value) {}
template<typename U>
explicit failure(failure<U>&& v): value(std::move(v.value)) {}
~failure() = default;
failure(const failure&) = default;
failure(failure&&) = default;
failure& operator=(const failure&) = default;
failure& operator=(failure&&) = default;
};
template<typename T>
success<typename std::remove_cv<typename std::remove_reference<T>::type>::type>
ok(T&& v)
{
return success<
typename std::remove_cv<typename std::remove_reference<T>::type>::type
>(std::forward<T>(v));
}
template<typename T>
failure<typename std::remove_cv<typename std::remove_reference<T>::type>::type>
err(T&& v)
{
return failure<
typename std::remove_cv<typename std::remove_reference<T>::type>::type
>(std::forward<T>(v));
}
inline success<std::string> ok(const char* literal)
{
return success<std::string>(std::string(literal));
}
inline failure<std::string> err(const char* literal)
{
return failure<std::string>(std::string(literal));
}
template<typename T, typename E>
struct result
{
using value_type = T;
using error_type = E;
using success_type = success<value_type>;
using failure_type = failure<error_type>;
result(const success_type& s): is_ok_(true)
{
auto tmp = ::new(std::addressof(this->succ)) success_type(s);
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
result(const failure_type& f): is_ok_(false)
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(f);
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
result(success_type&& s): is_ok_(true)
{
auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(s));
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
result(failure_type&& f): is_ok_(false)
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(f));
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
template<typename U>
result(const success<U>& s): is_ok_(true)
{
auto tmp = ::new(std::addressof(this->succ)) success_type(s.value);
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
template<typename U>
result(const failure<U>& f): is_ok_(false)
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(f.value);
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
template<typename U>
result(success<U>&& s): is_ok_(true)
{
auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(s.value));
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
template<typename U>
result(failure<U>&& f): is_ok_(false)
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(f.value));
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
result& operator=(const success_type& s)
{
this->cleanup();
this->is_ok_ = true;
auto tmp = ::new(std::addressof(this->succ)) success_type(s);
assert(tmp == std::addressof(this->succ));
(void)tmp;
return *this;
}
result& operator=(const failure_type& f)
{
this->cleanup();
this->is_ok_ = false;
auto tmp = ::new(std::addressof(this->fail)) failure_type(f);
assert(tmp == std::addressof(this->fail));
(void)tmp;
return *this;
}
result& operator=(success_type&& s)
{
this->cleanup();
this->is_ok_ = true;
auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(s));
assert(tmp == std::addressof(this->succ));
(void)tmp;
return *this;
}
result& operator=(failure_type&& f)
{
this->cleanup();
this->is_ok_ = false;
auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(f));
assert(tmp == std::addressof(this->fail));
(void)tmp;
return *this;
}
template<typename U>
result& operator=(const success<U>& s)
{
this->cleanup();
this->is_ok_ = true;
auto tmp = ::new(std::addressof(this->succ)) success_type(s.value);
assert(tmp == std::addressof(this->succ));
(void)tmp;
return *this;
}
template<typename U>
result& operator=(const failure<U>& f)
{
this->cleanup();
this->is_ok_ = false;
auto tmp = ::new(std::addressof(this->fail)) failure_type(f.value);
assert(tmp == std::addressof(this->fail));
(void)tmp;
return *this;
}
template<typename U>
result& operator=(success<U>&& s)
{
this->cleanup();
this->is_ok_ = true;
auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(s.value));
assert(tmp == std::addressof(this->succ));
(void)tmp;
return *this;
}
template<typename U>
result& operator=(failure<U>&& f)
{
this->cleanup();
this->is_ok_ = false;
auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(f.value));
assert(tmp == std::addressof(this->fail));
(void)tmp;
return *this;
}
~result() noexcept {this->cleanup();}
result(const result& other): is_ok_(other.is_ok())
{
if(other.is_ok())
{
auto tmp = ::new(std::addressof(this->succ)) success_type(other.as_ok());
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
else
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(other.as_err());
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
}
result(result&& other): is_ok_(other.is_ok())
{
if(other.is_ok())
{
auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(other.as_ok()));
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
else
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(other.as_err()));
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
}
template<typename U, typename F>
result(const result<U, F>& other): is_ok_(other.is_ok())
{
if(other.is_ok())
{
auto tmp = ::new(std::addressof(this->succ)) success_type(other.as_ok());
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
else
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(other.as_err());
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
}
template<typename U, typename F>
result(result<U, F>&& other): is_ok_(other.is_ok())
{
if(other.is_ok())
{
auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(other.as_ok()));
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
else
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(other.as_err()));
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
}
result& operator=(const result& other)
{
this->cleanup();
if(other.is_ok())
{
auto tmp = ::new(std::addressof(this->succ)) success_type(other.as_ok());
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
else
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(other.as_err());
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
is_ok_ = other.is_ok();
return *this;
}
result& operator=(result&& other)
{
this->cleanup();
if(other.is_ok())
{
auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(other.as_ok()));
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
else
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(other.as_err()));
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
is_ok_ = other.is_ok();
return *this;
}
template<typename U, typename F>
result& operator=(const result<U, F>& other)
{
this->cleanup();
if(other.is_ok())
{
auto tmp = ::new(std::addressof(this->succ)) success_type(other.as_ok());
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
else
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(other.as_err());
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
is_ok_ = other.is_ok();
return *this;
}
template<typename U, typename F>
result& operator=(result<U, F>&& other)
{
this->cleanup();
if(other.is_ok())
{
auto tmp = ::new(std::addressof(this->succ)) success_type(std::move(other.as_ok()));
assert(tmp == std::addressof(this->succ));
(void)tmp;
}
else
{
auto tmp = ::new(std::addressof(this->fail)) failure_type(std::move(other.as_err()));
assert(tmp == std::addressof(this->fail));
(void)tmp;
}
is_ok_ = other.is_ok();
return *this;
}
bool is_ok() const noexcept {return is_ok_;}
bool is_err() const noexcept {return !is_ok_;}
operator bool() const noexcept {return is_ok_;}
value_type& unwrap() &
{
if(is_err())
{
throw std::runtime_error("toml::result: bad unwrap: " +
format_error(this->as_err()));
}
return this->succ.value;
}
value_type const& unwrap() const&
{
if(is_err())
{
throw std::runtime_error("toml::result: bad unwrap: " +
format_error(this->as_err()));
}
return this->succ.value;
}
value_type&& unwrap() &&
{
if(is_err())
{
throw std::runtime_error("toml::result: bad unwrap: " +
format_error(this->as_err()));
}
return std::move(this->succ.value);
}
value_type& unwrap_or(value_type& opt) &
{
if(is_err()) {return opt;}
return this->succ.value;
}
value_type const& unwrap_or(value_type const& opt) const&
{
if(is_err()) {return opt;}
return this->succ.value;
}
value_type unwrap_or(value_type opt) &&
{
if(is_err()) {return opt;}
return this->succ.value;
}
error_type& unwrap_err() &
{
if(is_ok()) {throw std::runtime_error("toml::result: bad unwrap_err");}
return this->fail.value;
}
error_type const& unwrap_err() const&
{
if(is_ok()) {throw std::runtime_error("toml::result: bad unwrap_err");}
return this->fail.value;
}
error_type&& unwrap_err() &&
{
if(is_ok()) {throw std::runtime_error("toml::result: bad unwrap_err");}
return std::move(this->fail.value);
}
value_type& as_ok() & noexcept {return this->succ.value;}
value_type const& as_ok() const& noexcept {return this->succ.value;}
value_type&& as_ok() && noexcept {return std::move(this->succ.value);}
error_type& as_err() & noexcept {return this->fail.value;}
error_type const& as_err() const& noexcept {return this->fail.value;}
error_type&& as_err() && noexcept {return std::move(this->fail.value);}
// prerequisities
// F: T -> U
// retval: result<U, E>
template<typename F>
result<detail::return_type_of_t<F, value_type&>, error_type>
map(F&& f) &
{
if(this->is_ok()){return ok(f(this->as_ok()));}
return err(this->as_err());
}
template<typename F>
result<detail::return_type_of_t<F, value_type const&>, error_type>
map(F&& f) const&
{
if(this->is_ok()){return ok(f(this->as_ok()));}
return err(this->as_err());
}
template<typename F>
result<detail::return_type_of_t<F, value_type &&>, error_type>
map(F&& f) &&
{
if(this->is_ok()){return ok(f(std::move(this->as_ok())));}
return err(std::move(this->as_err()));
}
// prerequisities
// F: E -> F
// retval: result<T, F>
template<typename F>
result<value_type, detail::return_type_of_t<F, error_type&>>
map_err(F&& f) &
{
if(this->is_err()){return err(f(this->as_err()));}
return ok(this->as_ok());
}
template<typename F>
result<value_type, detail::return_type_of_t<F, error_type const&>>
map_err(F&& f) const&
{
if(this->is_err()){return err(f(this->as_err()));}
return ok(this->as_ok());
}
template<typename F>
result<value_type, detail::return_type_of_t<F, error_type&&>>
map_err(F&& f) &&
{
if(this->is_err()){return err(f(std::move(this->as_err())));}
return ok(std::move(this->as_ok()));
}
// prerequisities
// F: T -> U
// retval: U
template<typename F, typename U>
detail::return_type_of_t<F, value_type&>
map_or_else(F&& f, U&& opt) &
{
if(this->is_err()){return std::forward<U>(opt);}
return f(this->as_ok());
}
template<typename F, typename U>
detail::return_type_of_t<F, value_type const&>
map_or_else(F&& f, U&& opt) const&
{
if(this->is_err()){return std::forward<U>(opt);}
return f(this->as_ok());
}
template<typename F, typename U>
detail::return_type_of_t<F, value_type&&>
map_or_else(F&& f, U&& opt) &&
{
if(this->is_err()){return std::forward<U>(opt);}
return f(std::move(this->as_ok()));
}
// prerequisities
// F: E -> U
// retval: U
template<typename F, typename U>
detail::return_type_of_t<F, error_type&>
map_err_or_else(F&& f, U&& opt) &
{
if(this->is_ok()){return std::forward<U>(opt);}
return f(this->as_err());
}
template<typename F, typename U>
detail::return_type_of_t<F, error_type const&>
map_err_or_else(F&& f, U&& opt) const&
{
if(this->is_ok()){return std::forward<U>(opt);}
return f(this->as_err());
}
template<typename F, typename U>
detail::return_type_of_t<F, error_type&&>
map_err_or_else(F&& f, U&& opt) &&
{
if(this->is_ok()){return std::forward<U>(opt);}
return f(std::move(this->as_err()));
}
// prerequisities:
// F: func T -> U
// toml::err(error_type) should be convertible to U.
// normally, type U is another result<S, F> and E is convertible to F
template<typename F>
detail::return_type_of_t<F, value_type&>
and_then(F&& f) &
{
if(this->is_ok()){return f(this->as_ok());}
return err(this->as_err());
}
template<typename F>
detail::return_type_of_t<F, value_type const&>
and_then(F&& f) const&
{
if(this->is_ok()){return f(this->as_ok());}
return err(this->as_err());
}
template<typename F>
detail::return_type_of_t<F, value_type&&>
and_then(F&& f) &&
{
if(this->is_ok()){return f(std::move(this->as_ok()));}
return err(std::move(this->as_err()));
}
// prerequisities:
// F: func E -> U
// toml::ok(value_type) should be convertible to U.
// normally, type U is another result<S, F> and T is convertible to S
template<typename F>
detail::return_type_of_t<F, error_type&>
or_else(F&& f) &
{
if(this->is_err()){return f(this->as_err());}
return ok(this->as_ok());
}
template<typename F>
detail::return_type_of_t<F, error_type const&>
or_else(F&& f) const&
{
if(this->is_err()){return f(this->as_err());}
return ok(this->as_ok());
}
template<typename F>
detail::return_type_of_t<F, error_type&&>
or_else(F&& f) &&
{
if(this->is_err()){return f(std::move(this->as_err()));}
return ok(std::move(this->as_ok()));
}
// if *this is error, returns *this. otherwise, returns other.
result and_other(const result& other) const&
{
return this->is_err() ? *this : other;
}
result and_other(result&& other) &&
{
return this->is_err() ? std::move(*this) : std::move(other);
}
// if *this is okay, returns *this. otherwise, returns other.
result or_other(const result& other) const&
{
return this->is_ok() ? *this : other;
}
result or_other(result&& other) &&
{
return this->is_ok() ? std::move(*this) : std::move(other);
}
void swap(result<T, E>& other)
{
result<T, E> tmp(std::move(*this));
*this = std::move(other);
other = std::move(tmp);
return ;
}
private:
static std::string format_error(std::exception const& excpt)
{
return std::string(excpt.what());
}
template<typename U, typename std::enable_if<!std::is_base_of<
std::exception, U>::value, std::nullptr_t>::type = nullptr>
static std::string format_error(U const& others)
{
std::ostringstream oss; oss << others;
return oss.str();
}
void cleanup() noexcept
{
if(this->is_ok_) {this->succ.~success_type();}
else {this->fail.~failure_type();}
return;
}
private:
bool is_ok_;
union
{
success_type succ;
failure_type fail;
};
};
template<typename T, typename E>
void swap(result<T, E>& lhs, result<T, E>& rhs)
{
lhs.swap(rhs);
return;
}
// this might be confusing because it eagerly evaluated, while in the other
// cases operator && and || are short-circuited.
//
// template<typename T, typename E>
// inline result<T, E>
// operator&&(const result<T, E>& lhs, const result<T, E>& rhs) noexcept
// {
// return lhs.is_ok() ? rhs : lhs;
// }
//
// template<typename T, typename E>
// inline result<T, E>
// operator||(const result<T, E>& lhs, const result<T, E>& rhs) noexcept
// {
// return lhs.is_ok() ? lhs : rhs;
// }
// ----------------------------------------------------------------------------
// re-use result<T, E> as a optional<T> with none_t
namespace detail
{
struct none_t {};
inline bool operator==(const none_t&, const none_t&) noexcept {return true;}
inline bool operator!=(const none_t&, const none_t&) noexcept {return false;}
inline bool operator< (const none_t&, const none_t&) noexcept {return false;}
inline bool operator<=(const none_t&, const none_t&) noexcept {return true;}
inline bool operator> (const none_t&, const none_t&) noexcept {return false;}
inline bool operator>=(const none_t&, const none_t&) noexcept {return true;}
template<typename charT, typename traitsT>
std::basic_ostream<charT, traitsT>&
operator<<(std::basic_ostream<charT, traitsT>& os, const none_t&)
{
os << "none";
return os;
}
inline failure<none_t> none() noexcept {return failure<none_t>{none_t{}};}
} // detail
} // toml11
#endif// TOML11_RESULT_H