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Add missing erase(first, last) function to ordered_map (#3109)

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Niels Lohmann 2021-11-09 22:24:58 +01:00 committed by GitHub
parent 834918018e
commit e9f88c2fad
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4 changed files with 148 additions and 14 deletions
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57
include/nlohmann/ordered_map.hpp
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@ -107,16 +107,55 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
iterator erase(iterator pos)
{
auto it = pos;
// Since we cannot move const Keys, re-construct them in place
for (auto next = it; ++next != this->end(); ++it)
{
it->~value_type(); // Destroy but keep allocation
new (&*it) value_type{std::move(*next)};
return erase(pos, std::next(pos));
}
Container::pop_back();
return pos;
iterator erase(iterator first, iterator last)
{
const auto elements_affected = std::distance(first, last);
const auto offset = std::distance(Container::begin(), first);
// This is the start situation. We need to delete elements_affected
// elements (3 in this example: e, f, g), and need to return an
// iterator past the last deleted element (h in this example).
// Note that offset is the distance from the start of the vector
// to first. We will need this later.
// [ a, b, c, d, e, f, g, h, i, j ]
// ^ ^
// first last
// Since we cannot move const Keys, we re-construct them in place.
// We start at first and re-construct (viz. copy) the elements from
// the back of the vector. Example for first iteration:
// ,--------.
// v | destroy e and re-construct with h
// [ a, b, c, d, e, f, g, h, i, j ]
// ^ ^
// it it + elements_affected
for (auto it = first; std::next(it, elements_affected) != Container::end(); ++it)
{
it->~value_type(); // destroy but keep allocation
new (&*it) value_type{std::move(*std::next(it, elements_affected))}; // "move" next element to it
}
// [ a, b, c, d, h, i, j, h, i, j ]
// ^ ^
// first last
// remove the unneeded elements at the end of the vector
Container::resize(this->size() - static_cast<size_type>(elements_affected));
// [ a, b, c, d, h, i, j ]
// ^ ^
// first last
// first is now pointing past the last deleted element, but we cannot
// use this iterator, because it may have been invalidated by the
// resize call. Instead, we can return begin() + offset.
return Container::begin() + offset;
}
size_type count(const Key& key) const

57
single_include/nlohmann/json.hpp
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@ -17494,16 +17494,55 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
iterator erase(iterator pos)
{
auto it = pos;
// Since we cannot move const Keys, re-construct them in place
for (auto next = it; ++next != this->end(); ++it)
{
it->~value_type(); // Destroy but keep allocation
new (&*it) value_type{std::move(*next)};
return erase(pos, std::next(pos));
}
Container::pop_back();
return pos;
iterator erase(iterator first, iterator last)
{
const auto elements_affected = std::distance(first, last);
const auto offset = std::distance(Container::begin(), first);
// This is the start situation. We need to delete elements_affected
// elements (3 in this example: e, f, g), and need to return an
// iterator past the last deleted element (h in this example).
// Note that offset is the distance from the start of the vector
// to first. We will need this later.
// [ a, b, c, d, e, f, g, h, i, j ]
// ^ ^
// first last
// Since we cannot move const Keys, we re-construct them in place.
// We start at first and re-construct (viz. copy) the elements from
// the back of the vector. Example for first iteration:
// ,--------.
// v | destroy e and re-construct with h
// [ a, b, c, d, e, f, g, h, i, j ]
// ^ ^
// it it + elements_affected
for (auto it = first; std::next(it, elements_affected) != Container::end(); ++it)
{
it->~value_type(); // destroy but keep allocation
new (&*it) value_type{std::move(*std::next(it, elements_affected))}; // "move" next element to it
}
// [ a, b, c, d, h, i, j, h, i, j ]
// ^ ^
// first last
// remove the unneeded elements at the end of the vector
Container::resize(this->size() - static_cast<size_type>(elements_affected));
// [ a, b, c, d, h, i, j ]
// ^ ^
// first last
// first is now pointing past the last deleted element, but we cannot
// use this iterator, because it may have been invalidated by the
// resize call. Instead, we can return begin() + offset.
return Container::begin() + offset;
}
size_type count(const Key& key) const

39
test/src/unit-ordered_map.cpp
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@ -210,6 +210,45 @@ TEST_CASE("ordered_map")
++it2;
CHECK(it2 == om.end());
}
SECTION("with iterator pair")
{
SECTION("range in the middle")
{
// need more elements
om["vier"] = "four";
om["fünf"] = "five";
// delete "zwei" and "drei"
auto it = om.erase(om.begin() + 1, om.begin() + 3);
CHECK(it->first == "vier");
CHECK(om.size() == 3);
}
SECTION("range at the beginning")
{
// need more elements
om["vier"] = "four";
om["fünf"] = "five";
// delete "eins" and "zwei"
auto it = om.erase(om.begin(), om.begin() + 2);
CHECK(it->first == "drei");
CHECK(om.size() == 3);
}
SECTION("range at the end")
{
// need more elements
om["vier"] = "four";
om["fünf"] = "five";
// delete "vier" and "fünf"
auto it = om.erase(om.begin() + 3, om.end());
CHECK(it == om.end());
CHECK(om.size() == 3);
}
}
}
SECTION("count")

17
test/src/unit-regression2.cpp
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@ -746,6 +746,23 @@ TEST_CASE("regression tests 2")
std::vector<FooBar> foo;
j.get_to(foo);
}
SECTION("issue #3108 - ordered_json doesn't support range based erase")
{
ordered_json j = {1, 2, 2, 4};
auto last = std::unique(j.begin(), j.end());
j.erase(last, j.end());
CHECK(j.dump() == "[1,2,4]");
j.erase(std::remove_if(j.begin(), j.end(), [](const ordered_json & val)
{
return val == 2;
}), j.end());
CHECK(j.dump() == "[1,4]");
}
}
DOCTEST_CLANG_SUPPRESS_WARNING_POP