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#pragma once
#include <functional> // less
#include <initializer_list> // initializer_list
#include <iterator> // input_iterator_tag, iterator_traits
#include <memory> // allocator
#include <stdexcept> // for out_of_range
#include <type_traits> // enable_if, is_convertible
#include <utility> // pair
#include <vector> // vector
#include <nlohmann/detail/macro_scope.hpp>
namespace nlohmann
{
/// ordered_map: a minimal map-like container that preserves insertion order
/// for use within nlohmann::basic_json<ordered_map>
template <class Key, class T, class IgnoredLess = std::less<Key>,
class Allocator = std::allocator<std::pair<const Key, T>>>
struct ordered_map : std::vector<std::pair<const Key, T>, Allocator>
{
using key_type = Key;
using mapped_type = T;
using Container = std::vector<std::pair<const Key, T>, Allocator>;
using iterator = typename Container::iterator;
using const_iterator = typename Container::const_iterator;
using size_type = typename Container::size_type;
using value_type = typename Container::value_type;
// Explicit constructors instead of `using Container::Container`
// otherwise older compilers choke on it (GCC <= 5.5, xcode <= 9.4)
ordered_map(const Allocator& alloc = Allocator()) : Container{alloc} {}
template <class It>
ordered_map(It first, It last, const Allocator& alloc = Allocator())
: Container{first, last, alloc} {}
ordered_map(std::initializer_list<T> init, const Allocator& alloc = Allocator() )
: Container{init, alloc} {}
std::pair<iterator, bool> emplace(const key_type& key, T&& t)
{
for (auto it = this->begin(); it != this->end(); ++it)
{
if (it->first == key)
{
return {it, false};
}
}
Container::emplace_back(key, t);
return {--this->end(), true};
}
T& operator[](const Key& key)
{
return emplace(key, T{}).first->second;
}
const T& operator[](const Key& key) const
{
return at(key);
}
T& at(const Key& key)
{
for (auto it = this->begin(); it != this->end(); ++it)
{
if (it->first == key)
{
return it->second;
}
}
JSON_THROW(std::out_of_range("key not found"));
}
const T& at(const Key& key) const
{
for (auto it = this->begin(); it != this->end(); ++it)
{
if (it->first == key)
{
return it->second;
}
}
JSON_THROW(std::out_of_range("key not found"));
}
size_type erase(const Key& key)
{
for (auto it = this->begin(); it != this->end(); ++it)
{
if (it->first == key)
{
// 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)};
}
Container::pop_back();
return 1;
}
}
return 0;
}
iterator erase(iterator pos)
{
return erase(pos, std::next(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
{
for (auto it = this->begin(); it != this->end(); ++it)
{
if (it->first == key)
{
return 1;
}
}
return 0;
}
iterator find(const Key& key)
{
for (auto it = this->begin(); it != this->end(); ++it)
{
if (it->first == key)
{
return it;
}
}
return Container::end();
}
const_iterator find(const Key& key) const
{
for (auto it = this->begin(); it != this->end(); ++it)
{
if (it->first == key)
{
return it;
}
}
return Container::end();
}
std::pair<iterator, bool> insert( value_type&& value )
{
return emplace(value.first, std::move(value.second));
}
std::pair<iterator, bool> insert( const value_type& value )
{
for (auto it = this->begin(); it != this->end(); ++it)
{
if (it->first == value.first)
{
return {it, false};
}
}
Container::push_back(value);
return {--this->end(), true};
}
template<typename InputIt>
using require_input_iter = typename std::enable_if<std::is_convertible<typename std::iterator_traits<InputIt>::iterator_category,
std::input_iterator_tag>::value>::type;
template<typename InputIt, typename = require_input_iter<InputIt>>
void insert(InputIt first, InputIt last)
{
for (auto it = first; it != last; ++it)
{
insert(*it);
}
}
};
} // namespace nlohmann
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