Common: Add a Result class

This adds a lightweight, easy to use std::variant wrapper intended to
be used as a return type for functions that can return either a result
or an error code.
This commit is contained in:
Léo Lam 2018-03-02 23:27:29 +01:00
parent 7833f1a931
commit 1bdfedf3c6
3 changed files with 32 additions and 0 deletions

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@ -138,6 +138,7 @@
<ClInclude Include="PcapFile.h" />
<ClInclude Include="Profiler.h" />
<ClInclude Include="QoSSession.h" />
<ClInclude Include="Result.h" />
<ClInclude Include="ScopeGuard.h" />
<ClInclude Include="SDCardUtil.h" />
<ClInclude Include="Semaphore.h" />

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@ -59,6 +59,7 @@
<ClInclude Include="PcapFile.h" />
<ClInclude Include="Profiler.h" />
<ClInclude Include="QoSSession.h" />
<ClInclude Include="Result.h" />
<ClInclude Include="ScopeGuard.h" />
<ClInclude Include="SDCardUtil.h" />
<ClInclude Include="SettingsHandler.h" />

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@ -0,0 +1,30 @@
// Copyright 2018 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#pragma once
#include <variant>
namespace Common
{
template <typename ResultCode, typename T>
class Result final
{
public:
Result(ResultCode code) : m_variant{code} {}
Result(const T& t) : m_variant{t} {}
Result(T&& t) : m_variant{std::move(t)} {}
explicit operator bool() const { return Succeeded(); }
bool Succeeded() const { return std::holds_alternative<T>(m_variant); }
// Must only be called when Succeeded() returns false.
ResultCode Error() const { return std::get<ResultCode>(m_variant); }
// Must only be called when Succeeded() returns true.
const T& operator*() const { return std::get<T>(m_variant); }
const T* operator->() const { return &std::get<T>(m_variant); }
T& operator*() { return std::get<T>(m_variant); }
T* operator->() { return &std::get<T>(m_variant); }
private:
std::variant<ResultCode, T> m_variant;
};
} // namespace Common