mirror of https://github.com/djcb/mu.git
152 lines
3.0 KiB
C++
152 lines
3.0 KiB
C++
/*
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** Copyright (C) 2019-2020 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
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**
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** This program is free software; you can redistribute it and/or modify it
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** under the terms of the GNU General Public License as published by the
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** Free Software Foundation; either version 3, or (at your option) any
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** later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program; if not, write to the Free Software Foundation,
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** Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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**
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*/
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#ifndef MU_RESULT_HH__
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#define MU_RESULT_HH__
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#include "thirdparty/expected.hpp"
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#include "utils/mu-error.hh"
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namespace Mu {
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/**
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* A little Rust-envy...a Result is _either_ some value of type T, _or_ a Mu::Error
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*/
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template <typename T> using Result = tl::expected<T, Error>;
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/**
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* Ok() is not typically strictly needed (unlike Err), but imitates Rust's Ok
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* and it helps the reader.
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*
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* @param t the value to return
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*
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* @return a success Result<T>
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*/
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template <typename T>
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class Result<T>::expected
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// note: "class", not "typename";
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// https://stackoverflow.com/questions/46412754/class-name-injection-and-constructors
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Ok(T&& t)
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{
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return std::move(t);
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}
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/**
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* Implementation of Ok() for void results.
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*
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* @return a success Result<void>
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*/
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static inline Result<void>
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Ok()
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{
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return {};
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}
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/**
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* Return an error
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*
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* @param err the error
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*
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* @return error
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*/
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static inline tl::unexpected<Error>
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Err(Error&& err)
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{
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return tl::unexpected(std::move(err));
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}
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static inline tl::unexpected<Error>
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Err(const Error& err)
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{
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return tl::unexpected(err);
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}
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template<typename T>
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static inline tl::unexpected<Error>
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Err(const Result<T>& res)
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{
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return res.error();
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}
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template <typename T>
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static inline Result<void>
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Ok(const T& t)
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{
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if (t)
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return Ok();
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else
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return Err(t.error());
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}
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/*
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* convenience
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*/
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static inline tl::unexpected<Error>
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Err(Error::Code errcode, std::string&& msg="")
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{
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return Err(Error{errcode, std::move(msg)});
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}
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__attribute__((format(printf, 2, 0)))
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static inline tl::unexpected<Error>
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Err(Error::Code errcode, const char* frm, ...)
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{
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va_list args;
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va_start(args, frm);
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auto str{vformat(frm, args)};
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va_end(args);
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return Err(errcode, std::move(str));
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}
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__attribute__((format(printf, 3, 0)))
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static inline tl::unexpected<Error>
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Err(Error::Code errcode, GError **err, const char* frm, ...)
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{
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va_list args;
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va_start(args, frm);
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auto str{vformat(frm, args)};
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va_end(args);
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if (err && *err)
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str += format(" (%s)", (*err)->message ? (*err)->message : "");
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g_clear_error(err);
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return Err(errcode, std::move(str));
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}
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#define assert_valid_result(R) do { \
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if(!R) { \
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g_critical("error-result: %s", (R).error().what()); \
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} \
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} \
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while(0)
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}// namespace Mu
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#endif /* MU_RESULT_HH__ */
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