mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
129 lines
3.8 KiB
C++
129 lines
3.8 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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#include <functional>
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#include <boost/variant/static_visitor.hpp>
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namespace dev
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{
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/// Generic visitor used as follows:
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/// std::visit(GenericVisitor<Class1, Class2>(
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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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template <class...>
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struct GenericVisitor{};
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template <class Visitable, class... Others>
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struct GenericVisitor<Visitable, Others...>: public GenericVisitor<Others...>
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{
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using GenericVisitor<Others...>::operator ();
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explicit GenericVisitor(
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std::function<void(Visitable&)> _visitor,
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std::function<void(Others&)>... _otherVisitors
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):
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GenericVisitor<Others...>(std::move(_otherVisitors)...),
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m_visitor(std::move(_visitor))
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{}
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void operator()(Visitable& _v) const { m_visitor(_v); }
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std::function<void(Visitable&)> m_visitor;
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};
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template <>
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struct GenericVisitor<>: public boost::static_visitor<> {
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void operator()() const {}
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};
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/// Generic visitor with fallback:
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/// std::visit(GenericFallbackVisitor<Class1, Class2>(
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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 have a fallback and will NOT fail at
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/// compile-time if you do not specify all variants.
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template <class...>
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struct GenericFallbackVisitor{};
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template <class Visitable, class... Others>
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struct GenericFallbackVisitor<Visitable, Others...>: public GenericFallbackVisitor<Others...>
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{
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explicit GenericFallbackVisitor(
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std::function<void(Visitable&)> _visitor,
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std::function<void(Others&)>... _otherVisitors
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):
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GenericFallbackVisitor<Others...>(std::move(_otherVisitors)...),
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m_visitor(std::move(_visitor))
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{}
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using GenericFallbackVisitor<Others...>::operator ();
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void operator()(Visitable& _v) const { m_visitor(_v); }
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std::function<void(Visitable&)> m_visitor;
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};
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template <>
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struct GenericFallbackVisitor<>: public boost::static_visitor<> {
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template <class T>
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void operator()(T&) const { }
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};
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/// Generic visitor with fallback that can return a value:
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/// std::visit(GenericFallbackReturnsVisitor<ReturnType, Class1, Class2>(
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/// [](Class1& _c) { return _c.f(); },
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/// [](Class2& _c) { return _c.g(); }
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/// ), variant);
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/// This one DOES have a fallback and will NOT fail at
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/// compile-time if you do not specify all variants.
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/// The fallback {}-constructs the return value.
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template <class R, class...>
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struct GenericFallbackReturnsVisitor{};
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template <class R, class Visitable, class... Others>
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struct GenericFallbackReturnsVisitor<R, Visitable, Others...>: public GenericFallbackReturnsVisitor<R, Others...>
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{
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explicit GenericFallbackReturnsVisitor(
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std::function<R(Visitable&)> _visitor,
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std::function<R(Others&)>... _otherVisitors
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):
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GenericFallbackReturnsVisitor<R, Others...>(std::move(_otherVisitors)...),
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m_visitor(std::move(_visitor))
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{}
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using GenericFallbackReturnsVisitor<R, Others...>::operator ();
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R operator()(Visitable& _v) const { return m_visitor(_v); }
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std::function<R(Visitable&)> m_visitor;
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};
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template <class R>
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struct GenericFallbackReturnsVisitor<R>: public boost::static_visitor<R> {
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template <class T>
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R operator()(T&) const { return {}; }
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};
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}
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