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+/*
+ This file is part of solidity.
+
+ solidity is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ solidity is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with solidity. If not, see <http://www.gnu.org/licenses/>.
+*/
+#pragma once
+
+#include <string>
+
+namespace dev
+{
+
+/// Simple generic result that holds a value and an optional error message.
+/// Results can be implicitly converted to and created from the type of
+/// the value they hold. The class is mainly designed for a result type of
+/// bool or pointer type. The idea is that the default constructed value of
+/// the result type is interpreted as an error value.
+///
+/// Result<bool> check()
+/// {
+/// if (false)
+/// return Result<bool>("Error message.")
+/// return true;
+/// }
+///
+
+template <class ResultType>
+class Result
+{
+public:
+ Result(ResultType _value): Result(_value, std::string{}) {}
+ Result(std::string _message): Result(ResultType{}, std::move(_message)) {}
+
+ /// @{
+ /// @name Wrapper functions
+ /// Wrapper functions that provide implicit conversions to and explicit retrieval of
+ /// the value this result holds.
+ operator ResultType const&() const { return m_value; }
+ ResultType const& get() const { return m_value; }
+ /// @}
+
+ /// @returns the error message (can be empty).
+ std::string const& message() const { return m_message; }
+
+private:
+ explicit Result(ResultType _value, std::string _message):
+ m_value(std::move(_value)),
+ m_message(std::move(_message))
+ {}
+
+ ResultType m_value;
+ std::string m_message;
+};
+
+}