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add variant class with cleaner interface than boost::variant<>
This commit is contained in:
koe
parent
9367b432f6
commit
bc3cec4634
4 changed files with 575 additions and 0 deletions
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@ -81,6 +81,9 @@ target_link_libraries(common
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PRIVATE
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${OPENSSL_LIBRARIES}
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${EXTRA_LIBRARIES})
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target_include_directories(common
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PRIVATE
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${Boost_INCLUDE_DIRS})
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#monero_install_headers(common
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# ${common_headers})
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156
src/common/variant.h
Normal file
156
src/common/variant.h
Normal file
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@ -0,0 +1,156 @@
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// Copyright (c) 2022, The Monero Project
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without modification, are
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// permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this list of
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// conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list
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// of conditions and the following disclaimer in the documentation and/or other
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// materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its contributors may be
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// used to endorse or promote products derived from this software without specific
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// prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Variant wrapper class.
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#pragma once
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//local headers
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//third party headers
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#include <boost/blank.hpp>
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#include <boost/mpl/begin_end.hpp>
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#include <boost/mpl/distance.hpp>
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#include <boost/mpl/find.hpp>
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#include <boost/mpl/vector.hpp>
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#include <boost/none_t.hpp>
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#include <boost/variant/apply_visitor.hpp>
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#include <boost/variant/get.hpp>
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#include <boost/variant/static_visitor.hpp>
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#include <boost/variant/variant.hpp>
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//standard headers
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#include <stdexcept>
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#include <type_traits>
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#include <utility>
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//forward declarations
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namespace tools
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{
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[[noreturn]] inline void variant_static_visitor_blank_err()
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{ throw std::runtime_error("variant: tried to visit an empty variant."); }
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[[noreturn]] inline void variant_unwrap_err()
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{ throw std::runtime_error("variant: tried to access value of incorrect type."); }
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////
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// variant: convenience wrapper around boost::variant with a cleaner interface
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// - the value may be assigned to but is otherwise read-only
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// - the variant is 'optional' - an empty variant will evaluate to 'false' and an initialized variant will be 'true'
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///
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template <typename ResultT>
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struct variant_static_visitor : public boost::static_visitor<ResultT>
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{
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/// provide visitation for empty variants
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/// - add this to your visitor with: using variant_static_visitor::operator();
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[[noreturn]] ResultT operator()(const boost::blank) const { variant_static_visitor_blank_err(); }
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};
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template <typename... Types>
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class variant final
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{
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using VType = boost::variant<boost::blank, Types...>;
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public:
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//constructors
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/// default constructor
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variant() = default;
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variant(boost::none_t) : variant{} {} //act like boost::optional
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/// construct from variant type (use enable_if to avoid issues with copy/move constructor)
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template <typename T,
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typename std::enable_if<
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!std::is_same<
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std::remove_cv_t<std::remove_reference_t<T>>,
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variant<Types...>
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>::value,
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bool
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>::type = true>
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variant(T &&value) : m_value{std::forward<T>(value)} {}
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//overloaded operators
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/// boolean operator: true if the variant isn't empty/uninitialized
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explicit operator bool() const noexcept { return !this->is_empty(); }
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//member functions
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/// check if empty/uninitialized
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bool is_empty() const noexcept { return m_value.which() == 0; }
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/// check the variant type
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template <typename T>
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bool is_type() const noexcept { return this->index() == this->type_index_of<T>(); }
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/// try to get a read-only handle to the embedded value (return nullptr on failure)
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template <typename T>
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const T* try_unwrap() const
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{
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return boost::strict_get<T>(&m_value);
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}
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/// get a read-only handle to the embedded value
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template <typename T>
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const T& unwrap() const
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{
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const T *value_ptr{this->try_unwrap<T>()};
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if (!value_ptr) variant_unwrap_err();
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return *value_ptr;
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}
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/// get the type index of the currently stored type
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int index() const noexcept { return m_value.which(); }
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/// get the type index of a requested type (compile error for invalid types) (boost::mp11 is boost 1.66.0)
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template <typename T>
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static constexpr int type_index_of() noexcept
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{
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using types = boost::mpl::vector<boost::blank, Types...>;
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using elem = typename boost::mpl::find<types, T>::type;
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using begin = typename boost::mpl::begin<types>::type;
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return boost::mpl::distance<begin, elem>::value;
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}
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/// check if two variants have the same type
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static bool same_type(const variant<Types...> &v1, const variant<Types...> &v2) noexcept
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{ return v1.index() == v2.index(); }
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/// apply a visitor to the variant
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template <typename VisitorT>
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typename VisitorT::result_type visit(VisitorT &&visitor) const
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{
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return boost::apply_visitor(std::forward<VisitorT>(visitor), m_value);
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}
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private:
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//member variables
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/// variant of all value types
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VType m_value;
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};
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} //namespace tools
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@ -90,6 +90,7 @@ set(unit_tests_sources
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hardfork.cpp
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unbound.cpp
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uri.cpp
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variant.cpp
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varint.cpp
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ringct.cpp
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output_selection.cpp
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415
tests/unit_tests/variant.cpp
Normal file
415
tests/unit_tests/variant.cpp
Normal file
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@ -0,0 +1,415 @@
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// Copyright (c) 2023, The Monero Project
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without modification, are
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// permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this list of
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// conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list
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// of conditions and the following disclaimer in the documentation and/or other
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// materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its contributors may be
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// used to endorse or promote products derived from this software without specific
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// prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "common/variant.h"
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#include <boost/mpl/deref.hpp>
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#include <boost/variant/recursive_wrapper.hpp>
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#include <boost/variant/recursive_variant.hpp>
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#include "gtest/gtest.h"
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#include <sstream>
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#include <type_traits>
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#include <vector>
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using tools::variant;
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using tools::variant_static_visitor;
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namespace
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{
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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template <typename T>
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using strip_all_t = std::remove_reference_t<std::remove_cv_t<T>>;
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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template <typename T, typename U>
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using strip_same = std::is_same<strip_all_t<T>, strip_all_t<U>>;
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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template
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<
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typename PositiveType,
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typename TestType,
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typename... VariantTypes,
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class VecTypes = boost::mpl::vector<VariantTypes...>,
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class VecBegin = typename boost::mpl::begin<VecTypes>::type,
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class VecIndexT = typename boost::mpl::find<VecTypes, TestType>::type,
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size_t TYPE_INDEX = boost::mpl::distance<VecBegin, VecIndexT>::value,
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bool LAST_VARIANT_TYPE = TYPE_INDEX == sizeof...(VariantTypes) - 1
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>
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static std::enable_if_t<LAST_VARIANT_TYPE>
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test_is_type_match(const variant<VariantTypes...>& v)
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{
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constexpr bool expected = strip_same<PositiveType, TestType>();
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const bool actual = v.template is_type<TestType>();
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EXPECT_EQ(expected, actual);
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EXPECT_FALSE(v.template is_type<boost::blank>());
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}
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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template
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<
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typename PositiveType,
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typename TestType,
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typename... VariantTypes,
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class VecTypes = boost::mpl::vector<VariantTypes...>,
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class VecBegin = typename boost::mpl::begin<VecTypes>::type,
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class VecIndexT = typename boost::mpl::find<VecTypes, TestType>::type,
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size_t TYPE_INDEX = boost::mpl::distance<VecBegin, VecIndexT>::value,
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bool LAST_VARIANT_TYPE = TYPE_INDEX == sizeof...(VariantTypes) - 1
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>
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static std::enable_if_t<!LAST_VARIANT_TYPE>
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test_is_type_match(const variant<VariantTypes...>& v)
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{
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constexpr bool expected = strip_same<PositiveType, TestType>();
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const bool actual = v.template is_type<TestType>();
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EXPECT_EQ(expected, actual);
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using NextTypeIt = typename boost::mpl::advance<VecIndexT, boost::mpl::int_<1>>::type;
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using NextTestType = typename boost::mpl::deref<NextTypeIt>::type;
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test_is_type_match<PositiveType, NextTestType>(v);
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}
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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template
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<
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typename VariantType0,
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typename... VariantTypesRest,
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typename AssignType
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>
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static void test_is_type_ref
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(
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variant<VariantType0, VariantTypesRest...>& v,
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AssignType&& val
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)
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{
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v = val;
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test_is_type_match<AssignType, VariantType0>(v);
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}
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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template
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<
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typename VariantType0,
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typename... VariantTypesRest,
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typename AssignType0,
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typename... AssignTypesRest
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>
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static void test_is_type_ref
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(
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variant<VariantType0, VariantTypesRest...>& v,
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AssignType0&& val_0,
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AssignTypesRest&&... val_rest
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)
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{
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v = val_0;
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test_is_type_match<AssignType0, VariantType0>(v);
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test_is_type_ref(v, val_rest...);
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}
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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template <typename... VariantTypes>
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static void test_is_type_full(VariantTypes&&... test_vals)
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{
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variant<VariantTypes...> v;
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test_is_type_ref(v, test_vals...);
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}
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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template
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<
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size_t IJ = 0,
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typename... VariantTypes,
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bool END = IJ == sizeof...(VariantTypes) * sizeof...(VariantTypes)
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>
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static std::enable_if_t<END>
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test_same_type_ref
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(
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variant<VariantTypes...>& v1,
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variant<VariantTypes...>& v2,
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const std::tuple<VariantTypes...>& tup_i,
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const std::tuple<VariantTypes...>& tup_j
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)
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{ /* trivial end case */ }
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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template
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<
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size_t IJ = 0,
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typename... VariantTypes,
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bool END = IJ == sizeof...(VariantTypes) * sizeof...(VariantTypes)
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>
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static std::enable_if_t<!END>
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test_same_type_ref
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(
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variant<VariantTypes...>& v1,
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variant<VariantTypes...>& v2,
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const std::tuple<VariantTypes...>& tup_i,
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const std::tuple<VariantTypes...>& tup_j
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)
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{
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constexpr size_t I = IJ / sizeof...(VariantTypes);
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constexpr size_t J = IJ % sizeof...(VariantTypes);
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constexpr bool expected = I == J;
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v1 = std::get<I>(tup_i);
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v2 = std::get<J>(tup_j);
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const bool actual = variant<VariantTypes...>::same_type(v1, v2);
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EXPECT_EQ(expected, actual);
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test_same_type_ref<IJ + 1>(v1, v2, tup_i, tup_j);
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}
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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template <typename... VariantTypes>
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static void test_same_type_full
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(
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const std::tuple<VariantTypes...>& vals_i,
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const std::tuple<VariantTypes...>& vals_j
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)
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{
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using Variant = variant<VariantTypes...>;
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Variant v_i;
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Variant v_j;
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test_same_type_ref(v_i, v_j, vals_i, vals_j);
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}
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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struct test_stringify_visitor: public variant_static_visitor<std::string>
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{
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template <typename T>
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static std::string stringify(const T& t)
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{
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std::stringstream ss;
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ss << typeid(T).name();
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ss << "::";
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ss << t;
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return ss.str();
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}
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template <class Variant, typename T>
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static void test_visitation(const Variant& v, const T& t)
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{
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EXPECT_EQ(test_stringify_visitor::stringify(t), v.visit(test_stringify_visitor()));
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}
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// Make sure boost::blank errors
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using variant_static_visitor::operator();
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// Visitation implementation
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template <typename T>
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std::string operator()(const T& t) const
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{
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return test_stringify_visitor::stringify(t);
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}
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};
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} // anonymous namespace
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//-------------------------------------------------------------------------------------------------------------------
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//-------------------------------------------------------------------------------------------------------------------
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TEST(variant, operatorbool)
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{
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variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
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EXPECT_FALSE(v);
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v = (int16_t) 2023;
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EXPECT_TRUE(v);
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v = (int16_t) 0;
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EXPECT_TRUE(v);
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v = boost::blank{};
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EXPECT_FALSE(v);
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}
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//-------------------------------------------------------------------------------------------------------------------
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TEST(variant, is_empty)
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{
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variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
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EXPECT_TRUE(v.is_empty());
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v = (int16_t) 2023;
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EXPECT_FALSE(v.is_empty());
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v = (int16_t) 0;
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EXPECT_FALSE(v.is_empty());
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v = boost::blank{};
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EXPECT_TRUE(v.is_empty());
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variant<> v2;
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EXPECT_TRUE(v2.is_empty());
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v2 = boost::blank{};
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EXPECT_TRUE(v2.is_empty());
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}
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//-------------------------------------------------------------------------------------------------------------------
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TEST(variant, is_type)
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{
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variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
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EXPECT_TRUE(v.is_type<boost::blank>());
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v = (int16_t) 2023;
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EXPECT_TRUE(v.is_type<int16_t>());
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test_is_type_full((uint32_t) 2023, (char) '\n', std::string("HOWDY"));
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}
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//-------------------------------------------------------------------------------------------------------------------
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TEST(variant, try_unwrap)
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{
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variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
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EXPECT_FALSE(v.try_unwrap<int8_t>());
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v = (int16_t) 5252;
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ASSERT_TRUE(v.try_unwrap<int16_t>());
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EXPECT_EQ(5252, *v.try_unwrap<int16_t>());
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EXPECT_FALSE(v.try_unwrap<uint16_t>());
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EXPECT_FALSE(v.try_unwrap<std::string>());
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}
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//-------------------------------------------------------------------------------------------------------------------
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TEST(variant, unwrap)
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{
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variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
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EXPECT_THROW(v.unwrap<int8_t>(), std::runtime_error);
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v = (int16_t) 5252;
|
||||
EXPECT_EQ(5252, v.unwrap<int16_t>());
|
||||
EXPECT_THROW(v.unwrap<uint16_t>(), std::runtime_error);
|
||||
EXPECT_THROW(v.unwrap<std::string>(), std::runtime_error);
|
||||
}
|
||||
//-------------------------------------------------------------------------------------------------------------------
|
||||
TEST(variant, index)
|
||||
{
|
||||
variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
|
||||
EXPECT_EQ(0, v.index());
|
||||
v = (int8_t) 7;
|
||||
EXPECT_EQ(1, v.index());
|
||||
v = (uint8_t) 7;
|
||||
EXPECT_EQ(2, v.index());
|
||||
v = (int16_t) 7;
|
||||
EXPECT_EQ(3, v.index());
|
||||
v = (uint16_t) 7;
|
||||
EXPECT_EQ(4, v.index());
|
||||
v = "verifiable variant vying for vengence versus visa";
|
||||
EXPECT_EQ(5, v.index());
|
||||
}
|
||||
//-------------------------------------------------------------------------------------------------------------------
|
||||
TEST(variant, type_index_of)
|
||||
{
|
||||
variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
|
||||
EXPECT_EQ(0, decltype(v)::type_index_of<boost::blank>());
|
||||
EXPECT_EQ(1, decltype(v)::type_index_of<int8_t>());
|
||||
EXPECT_EQ(2, decltype(v)::type_index_of<uint8_t>());
|
||||
EXPECT_EQ(3, decltype(v)::type_index_of<int16_t>());
|
||||
EXPECT_EQ(4, decltype(v)::type_index_of<uint16_t>());
|
||||
EXPECT_EQ(5, decltype(v)::type_index_of<std::string>());
|
||||
}
|
||||
//-------------------------------------------------------------------------------------------------------------------
|
||||
TEST(variant, constexpr_type_index_of)
|
||||
{
|
||||
variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
|
||||
constexpr int TINDEX0 = decltype(v)::type_index_of<boost::blank>();
|
||||
EXPECT_EQ(0, TINDEX0);
|
||||
constexpr int TINDEX5 = decltype(v)::type_index_of<std::string>();
|
||||
EXPECT_EQ(5, TINDEX5);
|
||||
}
|
||||
//-------------------------------------------------------------------------------------------------------------------
|
||||
TEST(variant, same_type)
|
||||
{
|
||||
const std::tuple<int, std::string, char> vals_i(77840, "Hullubaloo", '\0');
|
||||
const std::tuple<int, std::string, char> vals_j(1876, "Canneck", '\t');
|
||||
test_same_type_full(vals_i, vals_j);
|
||||
}
|
||||
//-------------------------------------------------------------------------------------------------------------------
|
||||
TEST(variant, visit)
|
||||
{
|
||||
variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
|
||||
EXPECT_THROW(v.visit(test_stringify_visitor()), std::runtime_error);
|
||||
|
||||
v = "Rev";
|
||||
test_stringify_visitor::test_visitation(v, std::string("Rev"));
|
||||
|
||||
v = (int16_t) 2001;
|
||||
test_stringify_visitor::test_visitation(v, (int16_t) 2001);
|
||||
EXPECT_NE(test_stringify_visitor::stringify((uint16_t) 2001), v.visit(test_stringify_visitor()));
|
||||
}
|
||||
//-------------------------------------------------------------------------------------------------------------------
|
||||
TEST(variant, ad_hoc_recursion)
|
||||
{
|
||||
struct left_t;
|
||||
struct right_t;
|
||||
|
||||
using twisty = variant<boost::recursive_wrapper<left_t>, boost::recursive_wrapper<right_t>>;
|
||||
|
||||
struct left_t
|
||||
{
|
||||
twisty l;
|
||||
};
|
||||
|
||||
struct right_t
|
||||
{
|
||||
twisty r;
|
||||
};
|
||||
|
||||
auto right = [](twisty&& t = {}) -> twisty
|
||||
{
|
||||
right_t r;
|
||||
r.r = t;
|
||||
return r;
|
||||
};
|
||||
|
||||
auto left = [](twisty&& t = {}) -> twisty
|
||||
{
|
||||
left_t l;
|
||||
l.l = t;
|
||||
return l;
|
||||
};
|
||||
|
||||
struct twisty_counter: variant_static_visitor<std::pair<int, int>>
|
||||
{
|
||||
std::pair<int, int> operator()(boost::blank) const
|
||||
{
|
||||
return {0, 0};
|
||||
}
|
||||
|
||||
std::pair<int, int> operator()(const left_t& l) const
|
||||
{
|
||||
auto count = l.l.visit(twisty_counter());
|
||||
count.first += 1;
|
||||
return count;
|
||||
}
|
||||
|
||||
std::pair<int, int> operator()(const right_t& r) const
|
||||
{
|
||||
auto count = r.r.visit(twisty_counter());
|
||||
count.second += 1;
|
||||
return count;
|
||||
}
|
||||
};
|
||||
|
||||
const twisty tw = left(left(right(right(left(right(left(right(left()))))))));
|
||||
|
||||
int left_count, right_count;
|
||||
std::tie(left_count, right_count) = tw.visit(twisty_counter());
|
||||
|
||||
EXPECT_EQ(5, left_count);
|
||||
EXPECT_EQ(4, right_count);
|
||||
}
|
||||
//-------------------------------------------------------------------------------------------------------------------
|
||||
Loading…
Reference in a new issue