tomlplusplus/include/toml++/toml_node.h
Mark Gillard b2f36e38f1 added trivial abi attribute to date, time, time_offset
also:
- included <cassert> directly in 'debug' builds when TOML_ASSERT isn't defined
- minor preprocessor cleanup
- minor documentation fixes
2020-03-23 17:55:32 +02:00

526 lines
20 KiB
C++

//# This file is a part of toml++ and is subject to the the terms of the MIT license.
//# Copyright (c) 2019-2020 Mark Gillard <mark.gillard@outlook.com.au>
//# See https://github.com/marzer/tomlplusplus/blob/master/LICENSE for the full license text.
#pragma once
#include "toml_common.h"
TOML_START
{
/// \brief A TOML node.
///
/// \detail A parsed TOML document forms a tree made up of tables, arrays and values.
/// This type is the base of each of those, providing a lot of the polymorphic plumbing.
class TOML_INTERFACE TOML_API node
{
private:
friend class impl::parser;
source_region source_{};
protected:
node(node&& other) noexcept;
node& operator= (node&& rhs) noexcept;
template <typename T>
[[nodiscard]] TOML_ALWAYS_INLINE
impl::node_of<T>& ref_cast() & noexcept
{
return *reinterpret_cast<impl::node_of<T>*>(this);
}
template <typename T>
[[nodiscard]] TOML_ALWAYS_INLINE
impl::node_of<T>&& ref_cast() && noexcept
{
return std::move(*reinterpret_cast<impl::node_of<T>*>(this));
}
template <typename T>
[[nodiscard]] TOML_ALWAYS_INLINE
const impl::node_of<T>& ref_cast() const & noexcept
{
return *reinterpret_cast<const impl::node_of<T>*>(this);
}
template <typename N, typename T>
using ref_cast_type = decltype(std::declval<N>().template ref_cast<T>());
node() noexcept = default;
node(const node&) = delete;
node& operator= (const node&) = delete;
public:
virtual ~node() noexcept = default;
/// \brief Returns the node's type identifier.
[[nodiscard]] virtual node_type type() const noexcept = 0;
/// \brief Returns true if this node is a table.
[[nodiscard]] virtual bool is_table() const noexcept = 0;
/// \brief Returns true if this node is an array.
[[nodiscard]] virtual bool is_array() const noexcept = 0;
/// \brief Returns true if this node is a value.
[[nodiscard]] virtual bool is_value() const noexcept = 0;
/// \brief Returns true if this node is a string value.
[[nodiscard]] virtual bool is_string() const noexcept;
/// \brief Returns true if this node is an integer value.
[[nodiscard]] virtual bool is_integer() const noexcept;
/// \brief Returns true if this node is an floating-point value.
[[nodiscard]] virtual bool is_floating_point() const noexcept;
/// \brief Returns true if this node is an integer or floating-point value.
[[nodiscard]] virtual bool is_number() const noexcept;
/// \brief Returns true if this node is a boolean value.
[[nodiscard]] virtual bool is_boolean() const noexcept;
/// \brief Returns true if this node is a local date value.
[[nodiscard]] virtual bool is_date() const noexcept;
/// \brief Returns true if this node is a local time value.
[[nodiscard]] virtual bool is_time() const noexcept;
/// \brief Returns true if this node is a date-time value.
[[nodiscard]] virtual bool is_date_time() const noexcept;
/// \brief Returns true if this node is an array containing only tables.
[[nodiscard]] virtual bool is_array_of_tables() const noexcept;
/// \brief Checks if a node is a specific type.
///
/// \tparam T A TOML node or value type.
///
/// \returns Returns true if this node is an instance of the specified type.
template <typename T>
[[nodiscard]] TOML_ALWAYS_INLINE
bool is() const noexcept
{
using type = impl::unwrapped<impl::remove_cvref_t<T>>;
static_assert(
impl::is_value_or_node<type>,
"Template type parameter must be one of the TOML value types, a toml::table, or a toml::array"
);
if constexpr (std::is_same_v<type, table>) return is_table();
else if constexpr (std::is_same_v<type, array>) return is_array();
else if constexpr (std::is_same_v<type, string>) return is_string();
else if constexpr (std::is_same_v<type, int64_t>) return is_integer();
else if constexpr (std::is_same_v<type, double>) return is_floating_point();
else if constexpr (std::is_same_v<type, bool>) return is_boolean();
else if constexpr (std::is_same_v<type, date>) return is_date();
else if constexpr (std::is_same_v<type, time>) return is_time();
else if constexpr (std::is_same_v<type, date_time>) return is_date_time();
}
/// \brief Returns a pointer to the node as a toml::table, if it is one.
[[nodiscard]] virtual table* as_table() noexcept;
/// \brief Returns a pointer to the node as a toml::array, if it is one.
[[nodiscard]] virtual array* as_array() noexcept;
/// \brief Returns a pointer to the node as a toml::value<string>, if it is one.
[[nodiscard]] virtual toml::value<string>* as_string() noexcept;
/// \brief Returns a pointer to the node as a toml::value<int64_t>, if it is one.
[[nodiscard]] virtual toml::value<int64_t>* as_integer() noexcept;
/// \brief Returns a pointer to the node as a toml::value<double>, if it is one.
[[nodiscard]] virtual toml::value<double>* as_floating_point() noexcept;
/// \brief Returns a pointer to the node as a toml::value<bool>, if it is one.
[[nodiscard]] virtual toml::value<bool>* as_boolean() noexcept;
/// \brief Returns a pointer to the node as a toml::value<date>, if it is one.
[[nodiscard]] virtual toml::value<date>* as_date() noexcept;
/// \brief Returns a pointer to the node as a toml::value<time>, if it is one.
[[nodiscard]] virtual toml::value<time>* as_time() noexcept;
/// \brief Returns a pointer to the node as a toml::value<date_time>, if it is one.
[[nodiscard]] virtual toml::value<date_time>* as_date_time() noexcept;
[[nodiscard]] virtual const table* as_table() const noexcept;
[[nodiscard]] virtual const array* as_array() const noexcept;
[[nodiscard]] virtual const toml::value<string>* as_string() const noexcept;
[[nodiscard]] virtual const toml::value<int64_t>* as_integer() const noexcept;
[[nodiscard]] virtual const toml::value<double>* as_floating_point() const noexcept;
[[nodiscard]] virtual const toml::value<bool>* as_boolean() const noexcept;
[[nodiscard]] virtual const toml::value<date>* as_date() const noexcept;
[[nodiscard]] virtual const toml::value<time>* as_time() const noexcept;
[[nodiscard]] virtual const toml::value<date_time>* as_date_time() const noexcept;
/// \brief Gets the raw value contained by this node.
///
/// \detail The optional returned by this function will only contain a value if the node was an instance of
/// toml::value with the same value type as the template argument. Additionally, some type are allowed to
/// convert to each other, for instance asking for an integer when the value exists as a double,
/// or requesting a string value as a string_view: \cpp
/// auto tbl = toml::parse(R"(
/// int_val = 10
/// float_val = 25.6
/// string_val = "kek"
/// )"sv);
///
/// if (auto val = tbl.get("int_val"sv)->value<int64_t>())
/// std::cout << "'int_val' as int64_t: "sv << *val << std::endl;
/// if (auto val = tbl.get("int_val"sv)->value<double>())
/// std::cout << "'int_val' as double: "sv << *val << std::endl;
/// if (auto val = tbl.get("float_val"sv)->value<int64_t>())
/// std::cout << "'float_val' as int64_t: "sv << *val << std::endl;
/// if (auto val = tbl.get("float_val"sv)->value<double>())
/// std::cout << "'float_val' as double: "sv << *val << std::endl;
/// if (auto val = tbl.get("string_val"sv)->value<std::string>())
/// std::cout << "'string_val' as std::string: "sv << *val << std::endl;
/// if (auto val = tbl.get("string_val"sv)->value<std::string_view>())
/// std::cout << "'string_val' as std::string_view: "sv << *val << std::endl;
/// if (auto val = tbl.get("string_val"sv)->value<int64_t>())
/// std::cout << "this line won't be printed."sv << std::endl;
/// \ecpp
///
/// \out
/// 'int_val' as int64_t: 10
/// 'int_val' as double: 10
/// 'float_val' as int64_t: 25
/// 'float_val' as double: 25.6
/// 'string_val' as std::string: kek
/// 'string_val' as std::string_view: kek
/// \eout
///
/// \tparam T One of the TOML value types. Can also be a string_view.
///
/// \returns The underlying value if the node was a value of the matching type (or convertible to it), or an empty optional.
template <typename T>
[[nodiscard]] optional<T> value() const noexcept;
/// \brief Gets the raw value contained by this node, or a default.
///
/// \tparam T Default value type. Must be (or be promotable to) one of the TOML value types.
/// \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 node's underlying value, or the default if the node wasn't a value, wasn't the
/// correct type, or no conversion was possible.
///
/// \see node::value()
template <typename T>
[[nodiscard]] auto value_or(T&& default_value) const noexcept;
/// \brief Gets a pointer to the node as a more specific node type.
///
/// \details \cpp
///
/// auto int_value = node->as<int64_t>();
/// auto tbl = node->as<toml::table>();
/// if (int_value)
/// std::cout << "Node is a value<int64_t>" << std::endl;
/// else if (tbl)
/// std::cout << "Node is a table" << std::endl;
///
/// // fully-qualified value node types also work:
/// auto int_value2 = node->as<toml::value<int64_t>>();
/// if (int_value2)
/// std::cout << "Node is a value<int64_t>" << std::endl;
///
/// \ecpp
///
/// \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.
template <typename T>
[[nodiscard]] TOML_ALWAYS_INLINE
impl::node_of<T>* as() noexcept
{
using type = impl::unwrapped<T>;
static_assert(
impl::is_value_or_node<type>,
"Template type parameter must be one of the TOML value types, a toml::table, or a toml::array"
);
if constexpr (std::is_same_v<type, table>) return as_table();
else if constexpr (std::is_same_v<type, array>) return as_array();
else if constexpr (std::is_same_v<type, string>) return as_string();
else if constexpr (std::is_same_v<type, int64_t>) return as_integer();
else if constexpr (std::is_same_v<type, double>) return as_floating_point();
else if constexpr (std::is_same_v<type, bool>) return as_boolean();
else if constexpr (std::is_same_v<type, date>) return as_date();
else if constexpr (std::is_same_v<type, time>) return as_time();
else if constexpr (std::is_same_v<type, date_time>) return as_date_time();
}
/// \brief Gets a pointer to the node as a more specific node type (const overload).
template <typename T>
[[nodiscard]] TOML_ALWAYS_INLINE
const impl::node_of<T>* as() const noexcept
{
using type = impl::unwrapped<T>;
static_assert(
impl::is_value_or_node<type>,
"Template type parameter must be one of the TOML value types, a toml::table, or a toml::array"
);
if constexpr (std::is_same_v<type, table>) return as_table();
else if constexpr (std::is_same_v<type, array>) return as_array();
else if constexpr (std::is_same_v<type, string>) return as_string();
else if constexpr (std::is_same_v<type, int64_t>) return as_integer();
else if constexpr (std::is_same_v<type, double>) return as_floating_point();
else if constexpr (std::is_same_v<type, bool>) return as_boolean();
else if constexpr (std::is_same_v<type, date>) return as_date();
else if constexpr (std::is_same_v<type, time>) return as_time();
else if constexpr (std::is_same_v<type, date_time>) return as_date_time();
}
/// \brief Returns the source region responsible for generating this node during parsing.
[[nodiscard]] const source_region& source() const noexcept;
private:
template <typename FUNC, typename N, typename T>
static constexpr bool can_visit = std::is_invocable_v<FUNC, ref_cast_type<N, T>>;
template <typename FUNC, typename N>
static constexpr bool can_visit_any =
can_visit<FUNC, N, table>
|| can_visit<FUNC, N, array>
|| can_visit<FUNC, N, string>
|| can_visit<FUNC, N, int64_t>
|| can_visit<FUNC, N, double>
|| can_visit<FUNC, N, bool>
|| can_visit<FUNC, N, date>
|| can_visit<FUNC, N, time>
|| can_visit<FUNC, N, date_time>;
template <typename FUNC, typename N>
static constexpr bool can_visit_all =
can_visit<FUNC, N, table>
&& can_visit<FUNC, N, array>
&& can_visit<FUNC, N, string>
&& can_visit<FUNC, N, int64_t>
&& can_visit<FUNC, N, double>
&& can_visit<FUNC, N, bool>
&& can_visit<FUNC, N, date>
&& can_visit<FUNC, N, time>
&& can_visit<FUNC, N, date_time>;
#if TOML_EXCEPTIONS
template <typename FUNC, typename N, typename T>
static constexpr bool visit_is_nothrow_one =
!can_visit<FUNC, N, T>
|| std::is_nothrow_invocable_v<FUNC, ref_cast_type<N, T>>;
template <typename FUNC, typename N>
static constexpr bool visit_is_nothrow =
visit_is_nothrow_one<FUNC, N, table>
&& visit_is_nothrow_one<FUNC, N, array>
&& visit_is_nothrow_one<FUNC, N, string>
&& visit_is_nothrow_one<FUNC, N, int64_t>
&& visit_is_nothrow_one<FUNC, N, double>
&& visit_is_nothrow_one<FUNC, N, bool>
&& visit_is_nothrow_one<FUNC, N, date>
&& visit_is_nothrow_one<FUNC, N, time>
&& visit_is_nothrow_one<FUNC, N, date_time>;
#endif
template <typename FUNC, typename N, typename T, bool = can_visit<FUNC, N, T>>
struct visit_return_type final
{
using type = decltype(std::declval<FUNC>()(std::declval<ref_cast_type<N, T>>()));
};
template <typename FUNC, typename N, typename T>
struct visit_return_type<FUNC, N, T, false> final
{
using type = void;
};
template <typename A, typename B>
using nonvoid = std::conditional_t<std::is_void_v<A>, B, A>;
//# these functions are static helpers to preserve const and ref categories
//# (otherwise I'd have to implement them thrice)
//# ((propagation in C++: a modern horror story))
template <typename N, typename FUNC>
static decltype(auto) do_visit(N&& n, FUNC&& visitor)
TOML_MAY_THROW_UNLESS(visit_is_nothrow<FUNC&&, N&&>)
{
static_assert(
can_visit_any<FUNC&&, N&&>,
"Visitors must be invocable for at least one of the toml::node specializations"
);
switch (n.type())
{
case node_type::table:
if constexpr (can_visit<FUNC&&, N&&, table>)
return std::forward<FUNC>(visitor)(std::forward<N>(n).template ref_cast<table>());
break;
case node_type::array:
if constexpr (can_visit<FUNC&&, N&&, array>)
return std::forward<FUNC>(visitor)(std::forward<N>(n).template ref_cast<array>());
break;
case node_type::string:
if constexpr (can_visit<FUNC&&, N&&, string>)
return std::forward<FUNC>(visitor)(std::forward<N>(n).template ref_cast<string>());
break;
case node_type::integer:
if constexpr (can_visit<FUNC&&, N&&, int64_t>)
return std::forward<FUNC>(visitor)(std::forward<N>(n).template ref_cast<int64_t>());
break;
case node_type::floating_point:
if constexpr (can_visit<FUNC&&, N&&, double>)
return std::forward<FUNC>(visitor)(std::forward<N>(n).template ref_cast<double>());
break;
case node_type::boolean:
if constexpr (can_visit<FUNC&&, N&&, bool>)
return std::forward<FUNC>(visitor)(std::forward<N>(n).template ref_cast<bool>());
break;
case node_type::date:
if constexpr (can_visit<FUNC&&, N&&, date>)
return std::forward<FUNC>(visitor)(std::forward<N>(n).template ref_cast<date>());
break;
case node_type::time:
if constexpr (can_visit<FUNC&&, N&&, time>)
return std::forward<FUNC>(visitor)(std::forward<N>(n).template ref_cast<time>());
break;
case node_type::date_time:
if constexpr (can_visit<FUNC&&, N&&, date_time>)
return std::forward<FUNC>(visitor)(std::forward<N>(n).template ref_cast<date_time>());
break;
TOML_NO_DEFAULT_CASE;
}
if constexpr (can_visit_all<FUNC&&, N&&>)
TOML_UNREACHABLE;
else
{
using return_type =
nonvoid<typename visit_return_type<FUNC&&, N&&, table>::type,
nonvoid<typename visit_return_type<FUNC&&, N&&, array>::type,
nonvoid<typename visit_return_type<FUNC&&, N&&, string>::type,
nonvoid<typename visit_return_type<FUNC&&, N&&, int64_t>::type,
nonvoid<typename visit_return_type<FUNC&&, N&&, double>::type,
nonvoid<typename visit_return_type<FUNC&&, N&&, bool>::type,
nonvoid<typename visit_return_type<FUNC&&, N&&, date>::type,
nonvoid<typename visit_return_type<FUNC&&, N&&, time>::type,
typename visit_return_type<FUNC&&, N&&, date_time>::type
>>>>>>>>;
if constexpr (!std::is_void_v<return_type>)
{
static_assert(
std::is_default_constructible_v<return_type>,
"Non-exhaustive visitors must return a default-constructible type, or void"
);
return return_type{};
}
}
}
template <typename T, typename N>
[[nodiscard]] static decltype(auto) do_ref(N&& n) noexcept
{
using type = impl::unwrapped<T>;
static_assert(
impl::is_value_or_node<type>,
"Template type parameter must be one of the TOML value types, a toml::table, or a toml::array"
);
TOML_ASSERT(
n.template is<T>()
&& "template type argument T provided to toml::node::ref() didn't match the node's actual type"
);
if constexpr (impl::is_value<type>)
return std::forward<N>(n).template ref_cast<type>().get();
else
return std::forward<N>(n).template ref_cast<type>();
}
public:
/// \brief Invokes a visitor on the node based on the node's concrete type.
///
/// \details Visitation is useful when you expect
/// a node to be one of a set number of types and need
/// to handle these types differently. Using `visit()` allows
/// you to eliminate some of the casting/conversion boilerplate: \cpp
///
/// node.visit([](auto&& n)
/// {
/// if constexpr (toml::is_string<decltype(n)>)
/// do_something_with_a_string(*n)); //n is a toml::value<toml::string>
/// else if constexpr (toml::is_integer<decltype(n)>)
/// do_something_with_an_int(*n); //n is a toml::value<int64_t>
/// else
/// throw std::exception{ "Expected string or integer" };
/// });
///
/// \ecpp
///
/// \tparam FUNC A callable type invocable with one or more of the
/// toml++ node types.
///
/// \param visitor The visitor object.
///
/// \returns The return value of the visitor.
/// Can be void. Non-exhaustive visitors must return a default-constructible type.
///
/// \see https://en.wikipedia.org/wiki/Visitor_pattern
template <typename FUNC>
decltype(auto) visit(FUNC&& visitor) & TOML_MAY_THROW_UNLESS(visit_is_nothrow<FUNC&&, node&>)
{
return do_visit(*this, std::forward<FUNC>(visitor));
}
template <typename FUNC>
decltype(auto) visit(FUNC&& visitor) && TOML_MAY_THROW_UNLESS(visit_is_nothrow<FUNC&&, node&&>)
{
return do_visit(std::move(*this), std::forward<FUNC>(visitor));
}
template <typename FUNC>
decltype(auto) visit(FUNC&& visitor) const& TOML_MAY_THROW_UNLESS(visit_is_nothrow<FUNC&&, const node&>)
{
return do_visit(*this, std::forward<FUNC>(visitor));
}
/// \brief Gets a raw reference to a value node's underlying data.
///
/// \warning This function is dangerous if used carelessly and **WILL** break your code if 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);
///
/// auto& min_ref = tbl.get("min")->ref<int64_t>(); // this is OK
/// auto& max_ref = tbl.get("max")->ref<double>(); // hits assertion because the type is wrong
///
/// \ecpp
///
/// \tparam T One of the TOML value types.
///
/// \returns A reference to the underlying data.
template <typename T>
[[nodiscard]] impl::unwrapped<T>& ref() & noexcept
{
return do_ref<T>(*this);
}
template <typename T>
[[nodiscard]] impl::unwrapped<T>&& ref() && noexcept
{
return do_ref<T>(std::move(*this));
}
template <typename T>
[[nodiscard]] const impl::unwrapped<T>& ref() const& noexcept
{
return do_ref<T>(*this);
}
};
}
TOML_END