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700b95f4473cac1d900b807541daad0ca3d98f52
json/test/src/unit-class_iterator.cpp
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Florian Albrechtskirchinger 700b95f447 Make iterator operator++/--(int) equality-preserving (#3332) 
Commit f28fc22 introduced const qualifiers on post-(inc-/dec-)rement
operators of iterators. These qualifiers prevent the use of basic_json
in place of std::ranges::range, which requires the post-increment
operator to be equality-preserving.

These changes appear to be the result of ICC compiler suggestions, and
no further explanation is discernible from the PR discussion (#858).
Further testing revealed, that clang-tidy also suggests adding const to
prevent "accidental mutation of a temporary object".

As an alternative, this commit partially reverts f28fc22, removing all
added const qualifiers from return types and adds lvalue reference
qualifiers to the operator member functions instead.

Unit tests ensure the operators remain equality-preserving and
accidental mutation of temporaries following post-(inc-/dec-)rement is
prohibited.

Fixes #3331.
2022-03-08 10:10:50 +01:00

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/*
__ _____ _____ _____
__| | __| | | | JSON for Modern C++ (test suite)
| | |__ | | | | | | version 3.10.5
|_____|_____|_____|_|___| https://github.com/nlohmann/json
Licensed under the MIT License <http://opensource.org/licenses/MIT>.
SPDX-License-Identifier: MIT
Copyright (c) 2013-2022 Niels Lohmann <http://nlohmann.me>.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#include "doctest_compatibility.h"
#define JSON_TESTS_PRIVATE
#include <nlohmann/json.hpp>
using nlohmann::json;
template<typename Iter>
using can_post_increment_temporary = decltype((std::declval<Iter>()++)++);
template<typename Iter>
using can_post_decrement_temporary = decltype((std::declval<Iter>()--)--);
TEST_CASE("iterator class")
{
SECTION("construction")
{
SECTION("constructor")
{
SECTION("null")
{
json j(json::value_t::null);
json::iterator it(&j);
}
SECTION("object")
{
json j(json::value_t::object);
json::iterator it(&j);
}
SECTION("array")
{
json j(json::value_t::array);
json::iterator it(&j);
}
}
SECTION("copy assignment")
{
json j(json::value_t::null);
json::iterator it(&j);
json::iterator it2(&j);
it2 = it;
}
}
SECTION("initialization")
{
SECTION("set_begin")
{
SECTION("null")
{
json j(json::value_t::null);
json::iterator it(&j);
it.set_begin();
CHECK((it == j.begin()));
}
SECTION("object")
{
json j(json::value_t::object);
json::iterator it(&j);
it.set_begin();
CHECK((it == j.begin()));
}
SECTION("array")
{
json j(json::value_t::array);
json::iterator it(&j);
it.set_begin();
CHECK((it == j.begin()));
}
}
SECTION("set_end")
{
SECTION("null")
{
json j(json::value_t::null);
json::iterator it(&j);
it.set_end();
CHECK((it == j.end()));
}
SECTION("object")
{
json j(json::value_t::object);
json::iterator it(&j);
it.set_end();
CHECK((it == j.end()));
}
SECTION("array")
{
json j(json::value_t::array);
json::iterator it(&j);
it.set_end();
CHECK((it == j.end()));
}
}
}
SECTION("element access")
{
SECTION("operator*")
{
SECTION("null")
{
json j(json::value_t::null);
json::iterator it = j.begin();
CHECK_THROWS_AS(*it, json::invalid_iterator&);
CHECK_THROWS_WITH(*it, "[json.exception.invalid_iterator.214] cannot get value");
}
SECTION("number")
{
json j(17);
json::iterator it = j.begin();
CHECK(*it == json(17));
it = j.end();
CHECK_THROWS_AS(*it, json::invalid_iterator&);
CHECK_THROWS_WITH(*it, "[json.exception.invalid_iterator.214] cannot get value");
}
SECTION("object")
{
json j({{"foo", "bar"}});
json::iterator it = j.begin();
CHECK(*it == json("bar"));
}
SECTION("array")
{
json j({1, 2, 3, 4});
json::iterator it = j.begin();
CHECK(*it == json(1));
}
}
SECTION("operator->")
{
SECTION("null")
{
json j(json::value_t::null);
json::iterator it = j.begin();
CHECK_THROWS_AS(std::string(it->type_name()), json::invalid_iterator&);
CHECK_THROWS_WITH(std::string(it->type_name()), "[json.exception.invalid_iterator.214] cannot get value");
}
SECTION("number")
{
json j(17);
json::iterator it = j.begin();
CHECK(std::string(it->type_name()) == "number");
it = j.end();
CHECK_THROWS_AS(std::string(it->type_name()), json::invalid_iterator&);
CHECK_THROWS_WITH(std::string(it->type_name()), "[json.exception.invalid_iterator.214] cannot get value");
}
SECTION("object")
{
json j({{"foo", "bar"}});
json::iterator it = j.begin();
CHECK(std::string(it->type_name()) == "string");
}
SECTION("array")
{
json j({1, 2, 3, 4});
json::iterator it = j.begin();
CHECK(std::string(it->type_name()) == "number");
}
}
}
SECTION("increment/decrement")
{
SECTION("post-increment")
{
SECTION("null")
{
json j(json::value_t::null);
json::iterator it = j.begin();
CHECK((it.m_it.primitive_iterator.m_it == 1));
it++;
CHECK((it.m_it.primitive_iterator.m_it != 0 && it.m_it.primitive_iterator.m_it != 1));
}
SECTION("number")
{
json j(17);
json::iterator it = j.begin();
CHECK((it.m_it.primitive_iterator.m_it == 0));
it++;
CHECK((it.m_it.primitive_iterator.m_it == 1));
it++;
CHECK((it.m_it.primitive_iterator.m_it != 0 && it.m_it.primitive_iterator.m_it != 1));
}
SECTION("object")
{
json j({{"foo", "bar"}});
json::iterator it = j.begin();
CHECK((it.m_it.object_iterator == it.m_object->m_value.object->begin()));
it++;
CHECK((it.m_it.object_iterator == it.m_object->m_value.object->end()));
}
SECTION("array")
{
json j({1, 2, 3, 4});
json::iterator it = j.begin();
CHECK((it.m_it.array_iterator == it.m_object->m_value.array->begin()));
it++;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
it++;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
it++;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
it++;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator == it.m_object->m_value.array->end()));
}
}
SECTION("pre-increment")
{
SECTION("null")
{
json j(json::value_t::null);
json::iterator it = j.begin();
CHECK((it.m_it.primitive_iterator.m_it == 1));
++it;
CHECK((it.m_it.primitive_iterator.m_it != 0 && it.m_it.primitive_iterator.m_it != 1));
}
SECTION("number")
{
json j(17);
json::iterator it = j.begin();
CHECK((it.m_it.primitive_iterator.m_it == 0));
++it;
CHECK((it.m_it.primitive_iterator.m_it == 1));
++it;
CHECK((it.m_it.primitive_iterator.m_it != 0 && it.m_it.primitive_iterator.m_it != 1));
}
SECTION("object")
{
json j({{"foo", "bar"}});
json::iterator it = j.begin();
CHECK((it.m_it.object_iterator == it.m_object->m_value.object->begin()));
++it;
CHECK((it.m_it.object_iterator == it.m_object->m_value.object->end()));
}
SECTION("array")
{
json j({1, 2, 3, 4});
json::iterator it = j.begin();
CHECK((it.m_it.array_iterator == it.m_object->m_value.array->begin()));
++it;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
++it;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
++it;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
++it;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator == it.m_object->m_value.array->end()));
}
}
SECTION("post-decrement")
{
SECTION("null")
{
json j(json::value_t::null);
json::iterator it = j.end();
CHECK((it.m_it.primitive_iterator.m_it == 1));
}
SECTION("number")
{
json j(17);
json::iterator it = j.end();
CHECK((it.m_it.primitive_iterator.m_it == 1));
it--;
CHECK((it.m_it.primitive_iterator.m_it == 0));
it--;
CHECK((it.m_it.primitive_iterator.m_it != 0 && it.m_it.primitive_iterator.m_it != 1));
}
SECTION("object")
{
json j({{"foo", "bar"}});
json::iterator it = j.end();
CHECK((it.m_it.object_iterator == it.m_object->m_value.object->end()));
it--;
CHECK((it.m_it.object_iterator == it.m_object->m_value.object->begin()));
}
SECTION("array")
{
json j({1, 2, 3, 4});
json::iterator it = j.end();
CHECK((it.m_it.array_iterator == it.m_object->m_value.array->end()));
it--;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
it--;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
it--;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
it--;
CHECK((it.m_it.array_iterator == it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
}
}
SECTION("pre-decrement")
{
SECTION("null")
{
json j(json::value_t::null);
json::iterator it = j.end();
CHECK((it.m_it.primitive_iterator.m_it == 1));
}
SECTION("number")
{
json j(17);
json::iterator it = j.end();
CHECK((it.m_it.primitive_iterator.m_it == 1));
--it;
CHECK((it.m_it.primitive_iterator.m_it == 0));
--it;
CHECK((it.m_it.primitive_iterator.m_it != 0 && it.m_it.primitive_iterator.m_it != 1));
}
SECTION("object")
{
json j({{"foo", "bar"}});
json::iterator it = j.end();
CHECK((it.m_it.object_iterator == it.m_object->m_value.object->end()));
--it;
CHECK((it.m_it.object_iterator == it.m_object->m_value.object->begin()));
}
SECTION("array")
{
json j({1, 2, 3, 4});
json::iterator it = j.end();
CHECK((it.m_it.array_iterator == it.m_object->m_value.array->end()));
--it;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
--it;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
--it;
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
--it;
CHECK((it.m_it.array_iterator == it.m_object->m_value.array->begin()));
CHECK((it.m_it.array_iterator != it.m_object->m_value.array->end()));
}
}
}
SECTION("equality-preserving")
{
SECTION("post-increment")
{
SECTION("primitive_iterator_t")
{
using Iter = nlohmann::detail::primitive_iterator_t;
CHECK(std::is_same < decltype(std::declval<Iter&>()++), Iter >::value);
}
SECTION("iter_impl")
{
using Iter = nlohmann::detail::iter_impl<json>;
CHECK(std::is_same < decltype(std::declval<Iter&>()++), Iter >::value);
}
SECTION("json_reverse_iterator")
{
using Base = nlohmann::detail::iter_impl<json>;
using Iter = nlohmann::detail::json_reverse_iterator<Base>;
CHECK(std::is_same < decltype(std::declval<Iter&>()++), Iter >::value);
}
}
SECTION("post-decrement")
{
SECTION("primitive_iterator_t")
{
using Iter = nlohmann::detail::primitive_iterator_t;
CHECK(std::is_same < decltype(std::declval<Iter&>()--), Iter >::value);
}
SECTION("iter_impl")
{
using Iter = nlohmann::detail::iter_impl<json>;
CHECK(std::is_same < decltype(std::declval<Iter&>()--), Iter >::value );
}
SECTION("json_reverse_iterator")
{
using Base = nlohmann::detail::iter_impl<json>;
using Iter = nlohmann::detail::json_reverse_iterator<Base>;
CHECK(std::is_same < decltype(std::declval<Iter&>()--), Iter >::value );
}
}
}
// prevent "accidental mutation of a temporary object"
SECTION("cert-dcl21-cpp")
{
using nlohmann::detail::is_detected;
SECTION("post-increment")
{
SECTION("primitive_iterator_t")
{
using Iter = nlohmann::detail::primitive_iterator_t;
CHECK_FALSE(is_detected<can_post_increment_temporary, Iter&>::value);
}
SECTION("iter_impl")
{
using Iter = nlohmann::detail::iter_impl<json>;
CHECK_FALSE(is_detected<can_post_increment_temporary, Iter&>::value);
}
SECTION("json_reverse_iterator")
{
using Base = nlohmann::detail::iter_impl<json>;
using Iter = nlohmann::detail::json_reverse_iterator<Base>;
CHECK_FALSE(is_detected<can_post_increment_temporary, Iter&>::value);
}
}
SECTION("post-decrement")
{
SECTION("primitive_iterator_t")
{
using Iter = nlohmann::detail::primitive_iterator_t;
CHECK_FALSE(is_detected<can_post_decrement_temporary, Iter&>::value);
}
SECTION("iter_impl")
{
using Iter = nlohmann::detail::iter_impl<json>;
CHECK_FALSE(is_detected<can_post_decrement_temporary, Iter&>::value);
}
SECTION("json_reverse_iterator")
{
using Base = nlohmann::detail::iter_impl<json>;
using Iter = nlohmann::detail::json_reverse_iterator<Base>;
CHECK_FALSE(is_detected<can_post_decrement_temporary, Iter&>::value);
}
}
}
}
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