feat! refactor! Breaking changes of the NeBuild system.

Working on a TOML backend, refactored source code namespace. And add 'toml++' vendor library.

See commit details.

Signed-off-by: Amlal El Mahrouss <amlal@nekernel.org>

1 files changed, 839 insertions, 0 deletions

diff --git a/vendor/toml++/impl/node_view.hpp b/vendor/toml++/impl/node_view.hpp
new file mode 100644
index 0000000..fb63025
--- /dev/null
+++ b/vendor/toml++/impl/node_view.hpp
@@ -0,0 +1,839 @@
+//# This file is a part of toml++ and is subject to the the terms of the MIT license.
+//# Copyright (c) Mark Gillard <mark.gillard@outlook.com.au>
+//# See https://github.com/marzer/tomlplusplus/blob/master/LICENSE for the full license text.
+// SPDX-License-Identifier: MIT
+#pragma once
+
+#include "std_vector.hpp"
+#include "std_initializer_list.hpp"
+#include "print_to_stream.hpp"
+#include "node.hpp"
+#include "header_start.hpp"
+TOML_DISABLE_ARITHMETIC_WARNINGS;
+
+TOML_NAMESPACE_START
+{
+	/// \brief	A view of a node.
+	///
+	/// \detail A node_view is like a std::optional<toml::node&> (if such a construct were legal), with lots of
+	///			toml-specific stuff built-in. It _may_ represent a node, and allows you to do many of the
+	///			same operations that you'd do on nodes directly, as well as easily traversing the node tree by creating
+	/// 		subviews (via node_view::operator[]). \cpp
+	///
+	/// auto tbl = toml::parse(R"(
+	///
+	///		title = "my hardware store"
+	///
+	///		[[products]]
+	///		name = "Hammer"
+	///		sku = 738594937
+	///		keywords = [ "hammer", "construction", "build" ]
+	///
+	///		[[products]]
+	///		name = "Nail"
+	///		sku = 284758393
+	///		color = "gray"
+	///
+	/// )"sv);
+	///
+	/// std::cout << tbl["title"] << "\n";
+	/// std::cout << tbl["products"][0]["name"] << "\n";
+	/// std::cout << tbl["products"][0]["keywords"] << "\n";
+	/// std::cout << tbl["products"][0]["keywords"][2] << "\n";
+	///
+	/// tbl["products"][0]["keywords"].as_array()->push_back("heavy");
+	/// std::cout << tbl["products"][0]["keywords"] << "\n";
+	/// std::cout << "has product[2]: "sv << !!tbl["products"][2] << "\n";
+	/// std::cout << "product[2]: "sv << tbl["products"][2] << "\n";
+	/// \ecpp
+	///
+	/// \out
+	/// "my hardware store"
+	/// "Hammer"
+	/// [ "hammer", "construction", "build" ]
+	/// "build"
+	/// [ "hammer", "construction", "build", "heavy" ]
+	/// has product[2]: false
+	/// product[2]:
+	/// \eout
+	template <typename ViewedType>
+	class TOML_TRIVIAL_ABI node_view
+	{
+		static_assert(impl::is_one_of<ViewedType, toml::node, const toml::node>,
+					  "A toml::node_view<> must wrap toml::node or const toml::node.");
+
+	  public:
+		/// \brief	The node type being viewed - either `node` or `const node`.
+		using viewed_type = ViewedType;
+
+	  private:
+		template <typename T>
+		friend class node_view;
+
+		mutable viewed_type* node_ = nullptr;
+
+	  public:
+		/// \brief	Constructs an empty node view.
+		TOML_NODISCARD_CTOR
+		node_view() noexcept = default;
+
+		/// \brief	Constructs node_view of a specific node.
+		TOML_NODISCARD_CTOR
+		explicit node_view(viewed_type* node) noexcept //
+			: node_{ node }
+		{}
+
+		/// \brief	Constructs node_view of a specific node.
+		TOML_NODISCARD_CTOR
+		explicit node_view(viewed_type& node) noexcept //
+			: node_{ &node }
+		{}
+
+		/// \brief	Copy constructor.
+		TOML_NODISCARD_CTOR
+		node_view(const node_view&) noexcept = default;
+
+		/// \brief	Move constructor.
+		TOML_NODISCARD_CTOR
+		node_view(node_view&&) noexcept = default;
+
+		/// \brief	Copy-assignment operator.
+		node_view& operator=(const node_view&) & noexcept = default;
+
+		/// \brief	Move-assignment operator.
+		node_view& operator=(node_view&&) & noexcept = default;
+
+		/// \brief	Returns true if the view references a node.
+		TOML_PURE_INLINE_GETTER
+		explicit operator bool() const noexcept
+		{
+			return node_ != nullptr;
+		}
+
+		/// \brief	Returns the node that's being referenced by the view.
+		TOML_PURE_INLINE_GETTER
+		viewed_type* node() const noexcept
+		{
+			return node_;
+		}
+
+		/// \name Type checks
+		/// @{
+
+		/// \brief	Returns the type identifier for the viewed node.
+		TOML_PURE_GETTER
+		node_type type() const noexcept
+		{
+			return node_ ? node_->type() : node_type::none;
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::table.
+		TOML_PURE_GETTER
+		bool is_table() const noexcept
+		{
+			return node_ && node_->is_table();
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::array.
+		TOML_PURE_GETTER
+		bool is_array() const noexcept
+		{
+			return node_ && node_->is_array();
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::value<>.
+		TOML_PURE_GETTER
+		bool is_value() const noexcept
+		{
+			return node_ && node_->is_value();
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::value<string>.
+		TOML_PURE_GETTER
+		bool is_string() const noexcept
+		{
+			return node_ && node_->is_string();
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::value<int64_t>.
+		TOML_PURE_GETTER
+		bool is_integer() const noexcept
+		{
+			return node_ && node_->is_integer();
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::value<double>.
+		TOML_PURE_GETTER
+		bool is_floating_point() const noexcept
+		{
+			return node_ && node_->is_floating_point();
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::value<int64_t> or toml::value<double>.
+		TOML_PURE_GETTER
+		bool is_number() const noexcept
+		{
+			return node_ && node_->is_number();
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::value<bool>.
+		TOML_PURE_GETTER
+		bool is_boolean() const noexcept
+		{
+			return node_ && node_->is_boolean();
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::value<date>.
+		TOML_PURE_GETTER
+		bool is_date() const noexcept
+		{
+			return node_ && node_->is_date();
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::value<time>.
+		TOML_PURE_GETTER
+		bool is_time() const noexcept
+		{
+			return node_ && node_->is_time();
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::value<date_time>.
+		TOML_PURE_GETTER
+		bool is_date_time() const noexcept
+		{
+			return node_ && node_->is_date_time();
+		}
+
+		/// \brief	Returns true if the viewed node is a toml::array that contains only tables.
+		TOML_PURE_GETTER
+		bool is_array_of_tables() const noexcept
+		{
+			return node_ && node_->is_array_of_tables();
+		}
+
+		/// \brief	Checks if this view references a node of a specific type.
+		///
+		/// \tparam	T	A TOML node or value type.
+		///
+		/// \returns	Returns true if the viewed node is an instance of the specified type.
+		///
+		/// \see toml::node::is()
+		template <typename T>
+		TOML_PURE_GETTER
+		bool is() const noexcept
+		{
+			return node_ ? node_->template is<impl::unwrap_node<impl::remove_cvref<T>>>() : false;
+		}
+
+		/// \brief	Checks if the viewed node contains values/elements of only one type.
+		///
+		/// \detail \cpp
+		/// auto cfg = toml::parse("arr = [ 1, 2, 3, 4.0 ]");
+		///
+		/// toml::node* nonmatch{};
+		/// if (cfg["arr"].is_homogeneous(toml::node_type::integer, nonmatch))
+		/// 	std::cout << "array was homogeneous"sv << "\n";
+		/// else
+		/// 	std::cout << "array was not homogeneous!\n"
+		/// 	<< "first non-match was a "sv << nonmatch->type() << " at " << nonmatch->source() << "\n";
+		/// \ecpp
+		///
+		/// \out
+		/// array was not homogeneous!
+		///	first non-match was a floating-point at line 1, column 18
+		/// \eout
+		///
+		/// \param	ntype	A TOML node type. <br>
+		/// 				\conditional_return{toml::node_type::none} "is every element the same type?"
+		/// 				\conditional_return{Anything else} "is every element one of these?"
+		///
+		/// \param first_nonmatch	Reference to a pointer in which the address of the first non-matching element
+		/// 						will be stored if the return value is false.
+		///
+		/// \returns	True if the viewed node was homogeneous.
+		///
+		/// \remarks	Always returns `false` if the view does not reference a node, or if the viewed node is
+		/// 			an empty table or array.
+		TOML_NODISCARD
+		bool is_homogeneous(node_type ntype, viewed_type*& first_nonmatch) const noexcept
+		{
+			if (!node_)
+			{
+				first_nonmatch = {};
+				return false;
+			}
+			return node_->is_homogeneous(ntype, first_nonmatch);
+		}
+
+		/// \brief	Checks if the viewed node contains values/elements of only one type.
+		///
+		/// \detail \cpp
+		/// auto cfg = toml::parse("arr = [ 1, 2, 3 ]");
+		/// std::cout << "homogenous: "sv << cfg["arr"].is_homogeneous(toml::node_type::none) << "\n";
+		/// std::cout << "all floats: "sv << cfg["arr"].is_homogeneous(toml::node_type::floating_point) << "\n";
+		/// std::cout << "all arrays: "sv << cfg["arr"].is_homogeneous(toml::node_type::array) << "\n";
+		/// std::cout << "all ints:   "sv << cfg["arr"].is_homogeneous(toml::node_type::integer) << "\n";
+		/// \ecpp
+		///
+		/// \out
+		/// homogeneous: true
+		/// all floats:  false
+		/// all arrays:  false
+		/// all ints:    true
+		/// \eout
+		///
+		/// \param	ntype	A TOML node type. <br>
+		/// 				\conditional_return{toml::node_type::none} "is every element the same type?"
+		/// 				\conditional_return{Anything else} "is every element one of these?"
+		///
+		/// \returns	True if the viewed node was homogeneous.
+		///
+		/// \remarks	Always returns `false` if the view does not reference a node, or if the viewed node is
+		/// 			an empty table or array.
+		TOML_NODISCARD
+		bool is_homogeneous(node_type ntype) const noexcept
+		{
+			return node_ ? node_->is_homogeneous(ntype) : false;
+		}
+
+		/// \brief	Checks if the viewed node contains values/elements of only one type.
+		///
+		/// \detail \cpp
+		/// auto cfg = toml::parse("arr = [ 1, 2, 3 ]");
+		/// std::cout << "homogenous:   "sv << cfg["arr"].is_homogeneous() << "\n";
+		/// std::cout << "all doubles:  "sv << cfg["arr"].is_homogeneous<double>() << "\n";
+		/// std::cout << "all arrays:   "sv << cfg["arr"].is_homogeneous<toml::array>() << "\n";
+		/// std::cout << "all integers: "sv << cfg["arr"].is_homogeneous<int64_t>() << "\n";
+		/// \ecpp
+		///
+		/// \out
+		/// homogeneous: true
+		/// all floats:  false
+		/// all arrays:  false
+		/// all ints:    true
+		/// \eout
+		///
+		/// \tparam	ElemType	A TOML node or value type. <br>
+		/// 					\conditional_return{Left as `void`} "is every element the same type?" <br>
+		/// 					\conditional_return{Explicitly specified} "is every element a T?"
+		///
+		/// \returns	True if the viewed node was homogeneous.
+		///
+		/// \remarks	Always returns `false` if the view does not reference a node, or if the viewed node is
+		/// 			an empty table or array.
+		template <typename ElemType = void>
+		TOML_PURE_GETTER
+		bool is_homogeneous() const noexcept
+		{
+			return node_ ? node_->template is_homogeneous<impl::unwrap_node<impl::remove_cvref<ElemType>>>() : false;
+		}
+
+		/// @}
+
+		/// \name Type casts
+		/// @{
+
+		/// \brief	Gets a pointer to the viewed node as a more specific node type.
+		///
+		/// \tparam	T	The node type or TOML value type to cast to.
+		///
+		/// \returns	A pointer to the node as the given type, or nullptr if it was a different type.
+		///
+		/// \see toml::node::as()
+		template <typename T>
+		TOML_PURE_GETTER
+		auto* as() const noexcept
+		{
+			return node_ ? node_->template as<T>() : nullptr;
+		}
+
+		/// \brief	Returns a pointer to the viewed node as a toml::table, if it is one.
+		TOML_PURE_GETTER
+		auto* as_table() const noexcept
+		{
+			return as<table>();
+		}
+
+		/// \brief	Returns a pointer to the viewed node as a toml::array, if it is one.
+		TOML_PURE_GETTER
+		auto* as_array() const noexcept
+		{
+			return as<array>();
+		}
+
+		/// \brief	Returns a pointer to the viewed node as a toml::value<string>, if it is one.
+		TOML_PURE_GETTER
+		auto* as_string() const noexcept
+		{
+			return as<std::string>();
+		}
+
+		/// \brief	Returns a pointer to the viewed node as a toml::value<int64_t>, if it is one.
+		TOML_PURE_GETTER
+		auto* as_integer() const noexcept
+		{
+			return as<int64_t>();
+		}
+
+		/// \brief	Returns a pointer to the viewed node as a toml::value<double>, if it is one.
+		TOML_PURE_GETTER
+		auto* as_floating_point() const noexcept
+		{
+			return as<double>();
+		}
+
+		/// \brief	Returns a pointer to the viewed node as a toml::value<bool>, if it is one.
+		TOML_PURE_GETTER
+		auto* as_boolean() const noexcept
+		{
+			return as<bool>();
+		}
+
+		/// \brief	Returns a pointer to the viewed node as a toml::value<date>, if it is one.
+		TOML_PURE_GETTER
+		auto* as_date() const noexcept
+		{
+			return as<date>();
+		}
+
+		/// \brief	Returns a pointer to the viewed node as a toml::value<time>, if it is one.
+		TOML_PURE_GETTER
+		auto* as_time() const noexcept
+		{
+			return as<time>();
+		}
+
+		/// \brief	Returns a pointer to the viewed node as a toml::value<date_time>, if it is one.
+		TOML_PURE_GETTER
+		auto* as_date_time() const noexcept
+		{
+			return as<date_time>();
+		}
+
+		/// @}
+
+		/// \name Value retrieval
+		/// @{
+
+		/// \brief	Gets the value contained by the referenced node.
+		///
+		/// \detail This function has 'exact' retrieval semantics; the only return value types allowed are the
+		/// 		TOML native value types, or types that can losslessly represent a native value type (e.g.
+		/// 		std::wstring on Windows).
+		///
+		/// \tparam	T	One of the native TOML value types, or a type capable of losslessly representing one.
+		///
+		/// \returns	The underlying value if the node was a value of the
+		/// 			matching type (or losslessly convertible to it), or an empty optional.
+		///
+		/// \see node_view::value()
+		template <typename T>
+		TOML_NODISCARD
+		optional<T> value_exact() const noexcept(impl::value_retrieval_is_nothrow<T>)
+		{
+			if (node_)
+				return node_->template value_exact<T>();
+			return {};
+		}
+
+		/// \brief	Gets the value contained by the referenced node.
+		///
+		/// \detail This function has 'permissive' retrieval semantics; some value types are allowed
+		/// 		to convert to others (e.g. retrieving a boolean as an integer), and the specified return value
+		/// 		type can be any type where a reasonable conversion from a native TOML value exists
+		/// 		(e.g. std::wstring on Windows). If the source value cannot be represented by
+		/// 		the destination type, an empty optional is returned. See node::value() for examples.
+		///
+		/// \tparam	T	One of the native TOML value types, or a type capable of convertible to one.
+		///
+		/// \returns	The underlying value if the node was a value of the matching type (or convertible to it)
+		/// 			and within the range of the output type, or an empty optional.
+		///
+		/// \note	If you want strict value retrieval semantics that do not allow for any type conversions,
+		/// 		use node_view::value_exact() instead.
+		///
+		/// \see
+		/// 	- node_view::value()
+		///		- node_view::value_exact()
+		template <typename T>
+		TOML_NODISCARD
+		optional<T> value() const noexcept(impl::value_retrieval_is_nothrow<T>)
+		{
+			if (node_)
+				return node_->template value<T>();
+			return {};
+		}
+
+		/// \brief	Gets the raw value contained by the referenced node, or a default.
+		///
+		/// \tparam	T				Default value type. Must be one of the native TOML value types,
+		/// 						or convertible to it.
+		/// \param 	default_value	The default value to return if the node wasn't a value, wasn't the
+		/// 						correct type, or no conversion was possible.
+		///
+		/// \returns	The underlying value if the node was a value of the matching type (or convertible to it)
+		/// 			and within the range of the output type, or the provided default.
+		///
+		/// \note	This function has the same permissive retrieval semantics as node::value(). If you want strict
+		/// 		value retrieval semantics that do not allow for any type conversions, use node_view::value_exact()
+		/// 		instead.
+		///
+		/// \see
+		/// 	- node_view::value()
+		///		- node_view::value_exact()
+		template <typename T>
+		TOML_NODISCARD
+		auto value_or(T&& default_value) const noexcept(impl::value_retrieval_is_nothrow<T>)
+		{
+			using namespace ::toml::impl;
+
+			static_assert(!is_wide_string<T> || TOML_ENABLE_WINDOWS_COMPAT,
+						  "Retrieving values as wide-character strings is only "
+						  "supported on Windows with TOML_ENABLE_WINDOWS_COMPAT enabled.");
+
+			if constexpr (is_wide_string<T>)
+			{
+#if TOML_ENABLE_WINDOWS_COMPAT
+
+				if (node_)
+					return node_->value_or(static_cast<T&&>(default_value));
+				return std::wstring{ static_cast<T&&>(default_value) };
+
+#else
+
+				static_assert(impl::always_false<T>, "Evaluated unreachable branch!");
+
+#endif
+			}
+			else
+			{
+				using value_type =
+					std::conditional_t<std::is_pointer_v<std::decay_t<T>>,
+									   std::add_pointer_t<std::add_const_t<std::remove_pointer_t<std::decay_t<T>>>>,
+									   std::decay_t<T>>;
+
+				if (node_)
+					return node_->value_or(static_cast<T&&>(default_value));
+				if constexpr (std::is_pointer_v<value_type>)
+					return value_type{ default_value };
+				else
+					return static_cast<T&&>(default_value);
+			}
+		}
+
+		/// \brief	Gets a raw reference to the viewed node's underlying data.
+		///
+		/// \warning This function is dangerous if used carelessly and **WILL** break your code if the
+		/// 		 node_view didn't reference a node, or the chosen value type doesn't match the node's
+		/// 		 actual type. In debug builds an assertion will fire when invalid accesses are attempted: \cpp
+		///
+		/// auto tbl = toml::parse(R"(
+		///		min = 32
+		///		max = 45
+		/// )"sv);
+		///
+		/// int64_t& min_ref = tbl["min"].ref<int64_t>(); // matching type
+		/// double& max_ref = tbl["max"].ref<double>();  // mismatched type, hits assert()
+		/// int64_t& foo_ref = tbl["foo"].ref<int64_t>(); // nonexistent key, hits assert()
+		/// \ecpp
+		///
+		/// \note	Specifying explicit ref qualifiers acts as an explicit ref-category cast,
+		///			whereas specifying explicit cv-ref qualifiers merges them with whatever
+		///			the cv qualification of the viewed node is (to ensure cv-correctness is propagated), e.g.:
+		///			| node_view             | T                      | return type                  |
+		///			|-----------------------|------------------------|------------------------------|
+		///			| node_view<node>       | std::string            | std::string&                 |
+		///			| node_view<node>       | std::string&&          | std::string&&                |
+		///			| node_view<const node> | volatile std::string   | const volatile std::string&  |
+		///			| node_view<const node> | volatile std::string&& | const volatile std::string&& |
+		///
+		///
+		/// \tparam	T	One of the TOML value types.
+		///
+		/// \returns	A reference to the underlying data.
+		template <typename T>
+		TOML_PURE_INLINE_GETTER
+		decltype(auto) ref() const noexcept
+		{
+			TOML_ASSERT_ASSUME(node_ && "toml::node_view::ref() called on a node_view that did not reference a node");
+			return node_->template ref<T>();
+		}
+
+		/// @}
+
+		/// \name Visitation
+		/// @{
+
+	  private:
+		/// \cond
+		template <typename Func>
+		static constexpr bool visit_is_nothrow = noexcept(std::declval<viewed_type*>()->visit(std::declval<Func>()));
+		/// \endcond
+
+	  public:
+		/// \brief	Invokes a visitor on the viewed node based on its concrete type.
+		///
+		/// \remarks Has no effect if the view does not reference a node.
+		///
+		/// \see node::visit()
+		template <typename Func>
+		decltype(auto) visit(Func&& visitor) const noexcept(visit_is_nothrow<Func&&>)
+		{
+			using return_type = decltype(node_->visit(static_cast<Func&&>(visitor)));
+			if (node_)
+				return node_->visit(static_cast<Func&&>(visitor));
+			if constexpr (!std::is_void_v<return_type>)
+				return return_type{};
+		}
+
+		/// @}
+
+		/// \name Equality
+		/// @{
+
+	  public:
+		/// \brief	Returns true if the two views refer to nodes of the same type and value.
+		template <typename T>
+		TOML_PURE_GETTER
+		friend bool operator==(const node_view& lhs, const node_view<T>& rhs) noexcept
+		{
+			return impl::node_deep_equality(lhs.node_, rhs.node_);
+		}
+
+		/// \brief	Returns true if the two views do not refer to nodes of the same type and value.
+		template <typename T>
+		TOML_PURE_GETTER
+		friend bool operator!=(const node_view& lhs, const node_view<T>& rhs) noexcept
+		{
+			return !impl::node_deep_equality(lhs.node_, rhs.node_);
+		}
+
+		/// \brief	Returns true if the viewed node is a table with the same contents as RHS.
+		TOML_NODISCARD
+		friend bool operator==(const node_view& lhs, const table& rhs) noexcept
+		{
+			if (lhs.node_ == &rhs)
+				return true;
+			const auto tbl = lhs.as<table>();
+			return tbl && *tbl == rhs;
+		}
+		TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&, const table&, );
+
+		/// \brief	Returns true if the viewed node is an array with the same contents as RHS.
+		TOML_NODISCARD
+		friend bool operator==(const node_view& lhs, const array& rhs) noexcept
+		{
+			if (lhs.node_ == &rhs)
+				return true;
+			const auto arr = lhs.as<array>();
+			return arr && *arr == rhs;
+		}
+		TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&, const array&, );
+
+		/// \brief	Returns true if the viewed node is a value with the same value as RHS.
+		template <typename T>
+		TOML_NODISCARD
+		friend bool operator==(const node_view& lhs, const toml::value<T>& rhs) noexcept
+		{
+			if (lhs.node_ == &rhs)
+				return true;
+			const auto val = lhs.as<T>();
+			return val && *val == rhs;
+		}
+		TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&, const toml::value<T>&, template <typename T>);
+
+		/// \brief	Returns true if the viewed node is a value with the same value as RHS.
+		TOML_CONSTRAINED_TEMPLATE(impl::is_losslessly_convertible_to_native<T>, typename T)
+		TOML_NODISCARD
+		friend bool operator==(const node_view& lhs, const T& rhs) noexcept(!impl::is_wide_string<T>)
+		{
+			static_assert(!impl::is_wide_string<T> || TOML_ENABLE_WINDOWS_COMPAT,
+						  "Comparison with wide-character strings is only "
+						  "supported on Windows with TOML_ENABLE_WINDOWS_COMPAT enabled.");
+
+			if constexpr (impl::is_wide_string<T>)
+			{
+#if TOML_ENABLE_WINDOWS_COMPAT
+				return lhs == impl::narrow(rhs);
+#else
+				static_assert(impl::always_false<T>, "Evaluated unreachable branch!");
+#endif
+			}
+			else
+			{
+				const auto val = lhs.as<impl::native_type_of<T>>();
+				return val && *val == rhs;
+			}
+		}
+		TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&,
+									   const T&,
+									   TOML_CONSTRAINED_TEMPLATE(impl::is_losslessly_convertible_to_native<T>,
+																 typename T));
+
+		/// \brief	Returns true if the viewed node is an array with the same contents as the RHS initializer list.
+		template <typename T>
+		TOML_NODISCARD
+		friend bool operator==(const node_view& lhs,
+							   const std::initializer_list<T>& rhs) noexcept(!impl::is_wide_string<T>)
+		{
+			const auto arr = lhs.as<array>();
+			return arr && *arr == rhs;
+		}
+		TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&, const std::initializer_list<T>&, template <typename T>);
+
+		/// \brief	Returns true if the viewed node is an array with the same contents as the RHS vector.
+		template <typename T>
+		TOML_NODISCARD
+		friend bool operator==(const node_view& lhs, const std::vector<T>& rhs) noexcept(!impl::is_wide_string<T>)
+		{
+			const auto arr = lhs.as<array>();
+			return arr && *arr == rhs;
+		}
+		TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&, const std::vector<T>&, template <typename T>);
+
+		/// @}
+
+		/// \name Subviews
+		/// @{
+
+		/// \brief	Returns a view of the selected subnode.
+		///
+		/// \param 	key	The key of the node to retrieve
+		///
+		/// \returns	A view of the selected node if this node represented a table and it contained a
+		/// 			value at the given key, or an empty view.
+		TOML_NODISCARD
+		node_view operator[](std::string_view key) const noexcept
+		{
+			if (auto tbl = this->as_table())
+				return node_view{ tbl->get(key) };
+			return {};
+		}
+
+		/// \brief	Returns a view of the selected subnode.
+		///
+		/// \param 	path	A "TOML path" to the desired subnode
+		///
+		/// \returns	A view of the selected node if this node represented a table and it contained a
+		/// 			value at the given key, or an empty view.
+		TOML_NODISCARD
+		node_view operator[](const toml::path& path) const noexcept
+		{
+			return node_ ? node_->at_path(path) : node_view{};
+		}
+
+		/// \brief Returns a view of the subnode matching a fully-qualified "TOML path".
+		///
+		/// \see #toml::node::at_path(std::string_view)
+		TOML_NODISCARD
+		node_view at_path(std::string_view path) const noexcept
+		{
+			return node_ ? node_->at_path(path) : node_view{};
+		}
+
+		/// \brief Returns a view of the subnode matching a fully-qualified "TOML path".
+		///
+		/// \see #toml::node::at_path(const toml::path&)
+		TOML_NODISCARD
+		node_view at_path(const toml::path& path) const noexcept
+		{
+			return node_ ? node_->at_path(path) : node_view{};
+		}
+
+#if TOML_ENABLE_WINDOWS_COMPAT
+
+		/// \brief	Returns a view of the selected subnode.
+		///
+		/// \availability This overload is only available when #TOML_ENABLE_WINDOWS_COMPAT is enabled.
+		///
+		/// \param 	key	The key of the node to retrieve
+		///
+		/// \returns	A view of the selected node if this node represented a table and it contained a
+		/// 			value at the given key, or an empty view.
+		TOML_NODISCARD
+		node_view operator[](std::wstring_view key) const
+		{
+			if (auto tbl = this->as_table())
+				return node_view{ tbl->get(key) };
+			return {};
+		}
+
+		/// \brief Returns a view of the subnode matching a fully-qualified "TOML path".
+		///
+		/// \availability This overload is only available when #TOML_ENABLE_WINDOWS_COMPAT is enabled.
+		///
+		/// \see #toml::node::at_path(std::string_view)
+		TOML_NODISCARD
+		node_view at_path(std::wstring_view path) const
+		{
+			return node_ ? node_->at_path(path) : node_view{};
+		}
+
+#endif // TOML_ENABLE_WINDOWS_COMPAT
+
+		/// \brief	Returns a view of the selected subnode.
+		///
+		/// \param 	index The index of the node to retrieve
+		///
+		/// \returns	A view of the selected node if this node represented an array and it contained a
+		/// 			value at the given index, or an empty view.
+		TOML_NODISCARD
+		node_view operator[](size_t index) const noexcept
+		{
+			if (auto arr = this->as_array())
+				return node_view{ arr->get(index) };
+			return {};
+		}
+
+		/// @}
+
+#if TOML_ENABLE_FORMATTERS
+
+		/// \brief	Prints the viewed node out to a stream.
+		///
+		/// \availability This operator is only available when #TOML_ENABLE_FORMATTERS is enabled.
+		friend std::ostream& operator<<(std::ostream& os, const node_view& nv)
+		{
+			if (nv.node_)
+				nv.node_->visit([&os](const auto& n) { os << n; });
+			return os;
+		}
+
+#endif
+	};
+
+	/// \cond
+
+	template <typename T>
+	node_view(const T&) -> node_view<const node>;
+
+	template <typename T>
+	node_view(const T*) -> node_view<const node>;
+
+	template <typename T>
+	node_view(T&) -> node_view<node>;
+
+	template <typename T>
+	node_view(T*) -> node_view<node>;
+
+	/// \endcond
+}
+TOML_NAMESPACE_END;
+
+/// \cond
+TOML_NAMESPACE_START
+{
+	inline node::operator node_view<node>() noexcept
+	{
+		return node_view<node>{ this };
+	}
+
+	inline node::operator node_view<const node>() const noexcept
+	{
+		return node_view<const node>{ this };
+	}
+}
+TOML_NAMESPACE_END;
+/// \endcond
+
+#include "header_end.hpp"