mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
61 lines
1.8 KiB
C++
61 lines
1.8 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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/**
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* Visitor templates.
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*/
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#pragma once
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namespace dev
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{
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/**
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* Generic visitor used as follows:
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* std::visit(GenericVisitor{
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* [](Class1& _c) { _c.f(); },
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* [](Class2& _c) { _c.g(); }
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* }, variant);
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* This one does not have a fallback and will fail at
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* compile-time if you do not specify all variants.
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*
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* Fallback with no return (it will not fail if you do not specify all variants):
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* std::visit(GenericVisitor{
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* VisitorFallback<>{},
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* [](Class1& _c) { _c.f(); },
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* [](Class2& _c) { _c.g(); }
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* }, variant);
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*
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* Fallback with return type R (the fallback returns `R{}`:
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* std::visit(GenericVisitor{
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* VisitorFallback<R>{},
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* [](Class1& _c) { _c.f(); },
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* [](Class2& _c) { _c.g(); }
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* }, variant);
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*/
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template <typename...> struct VisitorFallback;
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template <typename R>
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struct VisitorFallback<R> { template<typename T> R operator()(T&&) const { return {}; } };
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template<>
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struct VisitorFallback<> { template<typename T> void operator()(T&&) const {} };
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template <typename... Visitors> struct GenericVisitor: Visitors... { using Visitors::operator()...; };
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template <typename... Visitors> GenericVisitor(Visitors...) -> GenericVisitor<Visitors...>;
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}
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