mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
86 lines
2.5 KiB
C++
86 lines
2.5 KiB
C++
/*
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This file is part of solidity.
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solidity is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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solidity 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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You should have received a copy of the GNU General Public License
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along with solidity. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <string>
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namespace dev
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{
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/// Simple generic result that holds a value and an optional error message.
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/// Results can be implicitly converted to and created from the type of
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/// the value they hold. The class is mainly designed for a result type of
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/// bool or pointer type. The idea is that the default constructed value of
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/// the result type is interpreted as an error value.
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///
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/// Result<bool> check()
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/// {
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/// if (false)
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/// return Result<bool>::err("Error message.")
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/// return true;
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/// }
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///
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template <class ResultType>
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class Result
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{
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public:
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/// Constructs a result with _value and an empty message.
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/// This is meant to be called with valid results. Please use
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/// the static err() member function to signal an error.
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Result(ResultType _value): Result(_value, std::string{}) {}
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/// Constructs a result with a default-constructed value and an
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/// error message.
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static Result<ResultType> err(std::string _message)
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{
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return Result{ResultType{}, std::move(_message)};
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}
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/// @{
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/// @name Wrapper functions
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/// Wrapper functions that provide implicit conversions to and explicit retrieval of
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/// the value this result holds.
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operator ResultType const&() const { return m_value; }
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ResultType const& get() const { return m_value; }
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/// @}
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/// @returns the error message (can be empty).
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std::string const& message() const { return m_message; }
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/// Merges _other into this using the _merger
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/// and appends the error messages. Meant to be called
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/// with logical operators like logical_and, etc.
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template<typename F>
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void merge(Result<ResultType> const& _other, F _merger)
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{
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m_value = _merger(m_value, _other.get());
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m_message += _other.message();
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}
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private:
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explicit Result(ResultType _value, std::string _message):
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m_value(std::move(_value)),
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m_message(std::move(_message))
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{}
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ResultType m_value;
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std::string m_message;
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};
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}
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