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add variant class with cleaner interface than boost::variant<>

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pull/8660/head
koe 2 years ago
parent 9367b432f6
commit bc3cec4634
4 changed files with 575 additions and 0 deletions
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3
src/common/CMakeLists.txt
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@ -81,6 +81,9 @@ target_link_libraries(common
PRIVATE
${OPENSSL_LIBRARIES}
${EXTRA_LIBRARIES})
target_include_directories(common
PRIVATE
${Boost_INCLUDE_DIRS})
#monero_install_headers(common
# ${common_headers})

156
src/common/variant.h
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@ -0,0 +1,156 @@
// Copyright (c) 2022, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Variant wrapper class.
#pragma once
//local headers
//third party headers
#include <boost/blank.hpp>
#include <boost/mpl/begin_end.hpp>
#include <boost/mpl/distance.hpp>
#include <boost/mpl/find.hpp>
#include <boost/mpl/vector.hpp>
#include <boost/none_t.hpp>
#include <boost/variant/apply_visitor.hpp>
#include <boost/variant/get.hpp>
#include <boost/variant/static_visitor.hpp>
#include <boost/variant/variant.hpp>
//standard headers
#include <stdexcept>
#include <type_traits>
#include <utility>
//forward declarations
namespace tools
{
[[noreturn]] inline void variant_static_visitor_blank_err()
{ throw std::runtime_error("variant: tried to visit an empty variant."); }
[[noreturn]] inline void variant_unwrap_err()
{ throw std::runtime_error("variant: tried to access value of incorrect type."); }
////
// variant: convenience wrapper around boost::variant with a cleaner interface
// - the value may be assigned to but is otherwise read-only
// - the variant is 'optional' - an empty variant will evaluate to 'false' and an initialized variant will be 'true'
///
template <typename ResultT>
struct variant_static_visitor : public boost::static_visitor<ResultT>
{
/// provide visitation for empty variants
/// - add this to your visitor with: using variant_static_visitor::operator();
[[noreturn]] ResultT operator()(const boost::blank) const { variant_static_visitor_blank_err(); }
};
template <typename... Types>
class variant final
{
using VType = boost::variant<boost::blank, Types...>;
public:
//constructors
/// default constructor
variant() = default;
variant(boost::none_t) : variant{} {} //act like boost::optional
/// construct from variant type (use enable_if to avoid issues with copy/move constructor)
template <typename T,
typename std::enable_if<
!std::is_same<
std::remove_cv_t<std::remove_reference_t<T>>,
variant<Types...>
>::value,
bool
>::type = true>
variant(T &&value) : m_value{std::forward<T>(value)} {}
//overloaded operators
/// boolean operator: true if the variant isn't empty/uninitialized
explicit operator bool() const noexcept { return !this->is_empty(); }
//member functions
/// check if empty/uninitialized
bool is_empty() const noexcept { return m_value.which() == 0; }
/// check the variant type
template <typename T>
bool is_type() const noexcept { return this->index() == this->type_index_of<T>(); }
/// try to get a read-only handle to the embedded value (return nullptr on failure)
template <typename T>
const T* try_unwrap() const
{
return boost::strict_get<T>(&m_value);
}
/// get a read-only handle to the embedded value
template <typename T>
const T& unwrap() const
{
const T *value_ptr{this->try_unwrap<T>()};
if (!value_ptr) variant_unwrap_err();
return *value_ptr;
}
/// get the type index of the currently stored type
int index() const noexcept { return m_value.which(); }
/// get the type index of a requested type (compile error for invalid types) (boost::mp11 is boost 1.66.0)
template <typename T>
static constexpr int type_index_of() noexcept
{
using types = boost::mpl::vector<boost::blank, Types...>;
using elem = typename boost::mpl::find<types, T>::type;
using begin = typename boost::mpl::begin<types>::type;
return boost::mpl::distance<begin, elem>::value;
}
/// check if two variants have the same type
static bool same_type(const variant<Types...> &v1, const variant<Types...> &v2) noexcept
{ return v1.index() == v2.index(); }
/// apply a visitor to the variant
template <typename VisitorT>
typename VisitorT::result_type visit(VisitorT &&visitor) const
{
return boost::apply_visitor(std::forward<VisitorT>(visitor), m_value);
}
private:
//member variables
/// variant of all value types
VType m_value;
};
} //namespace tools

1
tests/unit_tests/CMakeLists.txt
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@ -90,6 +90,7 @@ set(unit_tests_sources
hardfork.cpp
unbound.cpp
uri.cpp
variant.cpp
varint.cpp
ringct.cpp
output_selection.cpp

415
tests/unit_tests/variant.cpp
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@ -0,0 +1,415 @@
// Copyright (c) 2023, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "common/variant.h"
#include <boost/mpl/deref.hpp>
#include <boost/variant/recursive_wrapper.hpp>
#include <boost/variant/recursive_variant.hpp>
#include "gtest/gtest.h"
#include <sstream>
#include <type_traits>
#include <vector>
using tools::variant;
using tools::variant_static_visitor;
namespace
{
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
template <typename T>
using strip_all_t = std::remove_reference_t<std::remove_cv_t<T>>;
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
template <typename T, typename U>
using strip_same = std::is_same<strip_all_t<T>, strip_all_t<U>>;
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
template
<
typename PositiveType,
typename TestType,
typename... VariantTypes,
class VecTypes = boost::mpl::vector<VariantTypes...>,
class VecBegin = typename boost::mpl::begin<VecTypes>::type,
class VecIndexT = typename boost::mpl::find<VecTypes, TestType>::type,
size_t TYPE_INDEX = boost::mpl::distance<VecBegin, VecIndexT>::value,
bool LAST_VARIANT_TYPE = TYPE_INDEX == sizeof...(VariantTypes) - 1
>
static std::enable_if_t<LAST_VARIANT_TYPE>
test_is_type_match(const variant<VariantTypes...>& v)
{
constexpr bool expected = strip_same<PositiveType, TestType>();
const bool actual = v.template is_type<TestType>();
EXPECT_EQ(expected, actual);
EXPECT_FALSE(v.template is_type<boost::blank>());
}
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
template
<
typename PositiveType,
typename TestType,
typename... VariantTypes,
class VecTypes = boost::mpl::vector<VariantTypes...>,
class VecBegin = typename boost::mpl::begin<VecTypes>::type,
class VecIndexT = typename boost::mpl::find<VecTypes, TestType>::type,
size_t TYPE_INDEX = boost::mpl::distance<VecBegin, VecIndexT>::value,
bool LAST_VARIANT_TYPE = TYPE_INDEX == sizeof...(VariantTypes) - 1
>
static std::enable_if_t<!LAST_VARIANT_TYPE>
test_is_type_match(const variant<VariantTypes...>& v)
{
constexpr bool expected = strip_same<PositiveType, TestType>();
const bool actual = v.template is_type<TestType>();
EXPECT_EQ(expected, actual);
using NextTypeIt = typename boost::mpl::advance<VecIndexT, boost::mpl::int_<1>>::type;
using NextTestType = typename boost::mpl::deref<NextTypeIt>::type;
test_is_type_match<PositiveType, NextTestType>(v);
}
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
template
<
typename VariantType0,
typename... VariantTypesRest,
typename AssignType
>
static void test_is_type_ref
(
variant<VariantType0, VariantTypesRest...>& v,
AssignType&& val
)
{
v = val;
test_is_type_match<AssignType, VariantType0>(v);
}
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
template
<
typename VariantType0,
typename... VariantTypesRest,
typename AssignType0,
typename... AssignTypesRest
>
static void test_is_type_ref
(
variant<VariantType0, VariantTypesRest...>& v,
AssignType0&& val_0,
AssignTypesRest&&... val_rest
)
{
v = val_0;
test_is_type_match<AssignType0, VariantType0>(v);
test_is_type_ref(v, val_rest...);
}
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
template <typename... VariantTypes>
static void test_is_type_full(VariantTypes&&... test_vals)
{
variant<VariantTypes...> v;
test_is_type_ref(v, test_vals...);
}
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
template
<
size_t IJ = 0,
typename... VariantTypes,
bool END = IJ == sizeof...(VariantTypes) * sizeof...(VariantTypes)
>
static std::enable_if_t<END>
test_same_type_ref
(
variant<VariantTypes...>& v1,
variant<VariantTypes...>& v2,
const std::tuple<VariantTypes...>& tup_i,
const std::tuple<VariantTypes...>& tup_j
)
{ /* trivial end case */ }
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
template
<
size_t IJ = 0,
typename... VariantTypes,
bool END = IJ == sizeof...(VariantTypes) * sizeof...(VariantTypes)
>
static std::enable_if_t<!END>
test_same_type_ref
(
variant<VariantTypes...>& v1,
variant<VariantTypes...>& v2,
const std::tuple<VariantTypes...>& tup_i,
const std::tuple<VariantTypes...>& tup_j
)
{
constexpr size_t I = IJ / sizeof...(VariantTypes);
constexpr size_t J = IJ % sizeof...(VariantTypes);
constexpr bool expected = I == J;
v1 = std::get<I>(tup_i);
v2 = std::get<J>(tup_j);
const bool actual = variant<VariantTypes...>::same_type(v1, v2);
EXPECT_EQ(expected, actual);
test_same_type_ref<IJ + 1>(v1, v2, tup_i, tup_j);
}
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
template <typename... VariantTypes>
static void test_same_type_full
(
const std::tuple<VariantTypes...>& vals_i,
const std::tuple<VariantTypes...>& vals_j
)
{
using Variant = variant<VariantTypes...>;
Variant v_i;
Variant v_j;
test_same_type_ref(v_i, v_j, vals_i, vals_j);
}
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
struct test_stringify_visitor: public variant_static_visitor<std::string>
{
template <typename T>
static std::string stringify(const T& t)
{
std::stringstream ss;
ss << typeid(T).name();
ss << "::";
ss << t;
return ss.str();
}
template <class Variant, typename T>
static void test_visitation(const Variant& v, const T& t)
{
EXPECT_EQ(test_stringify_visitor::stringify(t), v.visit(test_stringify_visitor()));
}
// Make sure boost::blank errors
using variant_static_visitor::operator();
// Visitation implementation
template <typename T>
std::string operator()(const T& t) const
{
return test_stringify_visitor::stringify(t);
}
};
} // anonymous namespace
//-------------------------------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------------------------------
TEST(variant, operatorbool)
{
variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
EXPECT_FALSE(v);
v = (int16_t) 2023;
EXPECT_TRUE(v);
v = (int16_t) 0;
EXPECT_TRUE(v);
v = boost::blank{};
EXPECT_FALSE(v);
}
//-------------------------------------------------------------------------------------------------------------------
TEST(variant, is_empty)
{
variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
EXPECT_TRUE(v.is_empty());
v = (int16_t) 2023;
EXPECT_FALSE(v.is_empty());
v = (int16_t) 0;
EXPECT_FALSE(v.is_empty());
v = boost::blank{};
EXPECT_TRUE(v.is_empty());
variant<> v2;
EXPECT_TRUE(v2.is_empty());
v2 = boost::blank{};
EXPECT_TRUE(v2.is_empty());
}
//-------------------------------------------------------------------------------------------------------------------
TEST(variant, is_type)
{
variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
EXPECT_TRUE(v.is_type<boost::blank>());
v = (int16_t) 2023;
EXPECT_TRUE(v.is_type<int16_t>());
test_is_type_full((uint32_t) 2023, (char) '\n', std::string("HOWDY"));
}
//-------------------------------------------------------------------------------------------------------------------
TEST(variant, try_unwrap)
{
variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
EXPECT_FALSE(v.try_unwrap<int8_t>());
v = (int16_t) 5252;
ASSERT_TRUE(v.try_unwrap<int16_t>());
EXPECT_EQ(5252, *v.try_unwrap<int16_t>());
EXPECT_FALSE(v.try_unwrap<uint16_t>());
EXPECT_FALSE(v.try_unwrap<std::string>());
}
//-------------------------------------------------------------------------------------------------------------------
TEST(variant, unwrap)
{
variant<int8_t, uint8_t, int16_t, uint16_t, std::string> v;
EXPECT_THROW(v.unwrap<int8_t>(), std::runtime_error);
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);
}
//-------------------------------------------------------------------------------------------------------------------
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