tomlplusplus/include/toml++/toml_node_view.h
2021-01-02 17:48:47 +02:00

682 lines
25 KiB
C++

//# 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 "toml_table.h"
#include "toml_array.h"
#include "toml_value.h"
TOML_PUSH_WARNINGS
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_API 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:
using viewed_type = ViewedType;
private:
template <typename T> friend class TOML_NAMESPACE::node_view;
mutable viewed_type* node_ = nullptr;
template <typename Func>
static constexpr bool visit_is_nothrow
= noexcept(std::declval<viewed_type*>()->visit(std::declval<Func&&>()));
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 Copy-assignment operator.
node_view& operator= (const node_view&) & noexcept = default;
///// \brief Move constructor.
TOML_NODISCARD_CTOR
node_view(node_view&&) noexcept = default;
///// \brief Move-assignment operator.
node_view& operator= (node_view&&) & noexcept = default;
/// \brief Returns true if the view references a node.
[[nodiscard]] explicit operator bool() const noexcept { return node_ != nullptr; }
/// \brief Returns the node that's being referenced by the view.
[[nodiscard]] viewed_type* node() const noexcept { return node_; }
[[nodiscard, deprecated("use node_view::node() instead")]]
viewed_type* get() const noexcept { return node_; }
/// \brief Returns the type identifier for the viewed node.
[[nodiscard]] node_type type() const noexcept { return node_ ? node_->type() : node_type::none; }
/// \brief Returns true if the viewed node is a toml::table.
[[nodiscard]] bool is_table() const noexcept { return node_ && node_->is_table(); }
/// \brief Returns true if the viewed node is a toml::array.
[[nodiscard]] bool is_array() const noexcept { return node_ && node_->is_array(); }
/// \brief Returns true if the viewed node is a toml::value<>.
[[nodiscard]] bool is_value() const noexcept { return node_ && node_->is_value(); }
/// \brief Returns true if the viewed node is a toml::value<string>.
[[nodiscard]] bool is_string() const noexcept { return node_ && node_->is_string(); }
/// \brief Returns true if the viewed node is a toml::value<int64_t>.
[[nodiscard]] bool is_integer() const noexcept { return node_ && node_->is_integer(); }
/// \brief Returns true if the viewed node is a toml::value<double>.
[[nodiscard]] 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>.
[[nodiscard]] bool is_number() const noexcept { return node_ && node_->is_number(); }
/// \brief Returns true if the viewed node is a toml::value<bool>.
[[nodiscard]] bool is_boolean() const noexcept { return node_ && node_->is_boolean(); }
/// \brief Returns true if the viewed node is a toml::value<date>.
[[nodiscard]] bool is_date() const noexcept { return node_ && node_->is_date(); }
/// \brief Returns true if the viewed node is a toml::value<time>.
[[nodiscard]] bool is_time() const noexcept { return node_ && node_->is_time(); }
/// \brief Returns true if the viewed node is a toml::value<date_time>.
[[nodiscard]] 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.
[[nodiscard]] 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>
[[nodiscard]]
bool is() const noexcept
{
return node_ ? node_->template is<T>() : false;
}
/// \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>
[[nodiscard]]
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.
[[nodiscard]] auto as_table() const noexcept { return as<table>(); }
/// \brief Returns a pointer to the viewed node as a toml::array, if it is one.
[[nodiscard]] 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.
[[nodiscard]] 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.
[[nodiscard]] 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.
[[nodiscard]] 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.
[[nodiscard]] 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.
[[nodiscard]] 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.
[[nodiscard]] 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.
[[nodiscard]] auto as_date_time() const noexcept { return as<date_time>(); }
/// \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>
/// <strong><em>toml::node_type::none: </em></strong> "is every element the same type?" <br>
/// <strong><em>Anything else:</em></strong> "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.
[[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>
/// <strong><em>toml::node_type::none: </em></strong> "is every element the same type?" <br>
/// <strong><em>Anything else:</em></strong> "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.
[[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>
/// <strong><em>Left as `void`:</em></strong> "is every element the same type?" <br>
/// <strong><em>Explicitly specified:</em></strong> "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>
[[nodiscard]]
bool is_homogeneous() const noexcept
{
return node_ ? node_->template is_homogeneous<impl::unwrap_node<ElemType>>() : false;
}
/// \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>
[[nodiscard]]
optional<T> value_exact() const noexcept
{
if (node_)
return node_->template value_exact<T>();
return {};
}
TOML_PUSH_WARNINGS
TOML_DISABLE_INIT_WARNINGS
/// \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.
///
/// \attention 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>
[[nodiscard]]
optional<T> value() const noexcept
{
if (node_)
return node_->template value<T>();
return {};
}
TOML_POP_WARNINGS
/// \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.
///
/// \attention 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>
[[nodiscard]]
auto value_or(T&& default_value) const noexcept
{
using namespace ::toml::impl;
static_assert(
!is_wide_string<T> || TOML_WINDOWS_COMPAT,
"Retrieving values as wide-character strings is only "
"supported on Windows with TOML_WINDOWS_COMPAT enabled."
);
if constexpr (is_wide_string<T>)
{
#if TOML_WINDOWS_COMPAT
if (node_)
return node_->value_or(std::forward<T>(default_value));
return std::wstring{ std::forward<T>(default_value) };
#else
static_assert(impl::dependent_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(std::forward<T>(default_value));
if constexpr (std::is_pointer_v<value_type>)
return value_type{ default_value };
else
return std::forward<T>(default_value);
}
}
/// \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(std::forward<Func>(visitor)));
if (node_)
return node_->visit(std::forward<Func>(visitor));
if constexpr (!std::is_void_v<return_type>)
return return_type{};
}
/// \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
///
/// \tparam T One of the TOML value types.
///
/// \returns A reference to the underlying data.
template <typename T>
[[nodiscard]]
decltype(auto) ref() const noexcept
{
TOML_ASSERT(
node_
&& "toml::node_view::ref() called on a node_view that did not reference a node"
);
return node_->template ref<impl::unwrap_node<T>>();
}
/// \brief Returns true if the viewed node is a table with the same contents as RHS.
[[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.
[[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>
[[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.
template <typename T, typename = std::enable_if_t<
impl::is_native<T>
|| impl::is_losslessly_convertible_to_native<T>
>>
[[nodiscard]]
friend bool operator == (const node_view& lhs, const T& rhs) noexcept
{
static_assert(
!impl::is_wide_string<T> || TOML_WINDOWS_COMPAT,
"Comparison with wide-character strings is only "
"supported on Windows with TOML_WINDOWS_COMPAT enabled."
);
if constexpr (impl::is_wide_string<T>)
{
#if TOML_WINDOWS_COMPAT
return lhs == impl::narrow(rhs);
#else
static_assert(impl::dependent_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&,
template <typename T, typename = std::enable_if_t<
impl::is_native<T>
|| impl::is_losslessly_convertible_to_native<T>
>>
)
/// \brief Returns true if the viewed node is an array with the same contents as the RHS initializer list.
template <typename T>
[[nodiscard]]
friend bool operator == (const node_view& lhs, const std::initializer_list<T>& rhs) noexcept
{
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>
[[nodiscard]]
friend bool operator == (const node_view& lhs, const std::vector<T>& rhs) noexcept
{
const auto arr = lhs.as<array>();
return arr && *arr == rhs;
}
TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&, const std::vector<T>&, template <typename T>)
/// \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.
[[nodiscard]]
node_view operator[] (std::string_view key) const noexcept
{
if (auto tbl = this->as_table())
return node_view{ tbl->get(key) };
return node_view{ nullptr };
}
#if TOML_WINDOWS_COMPAT
/// \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.
///
/// \attention This overload is only available when #TOML_WINDOWS_COMPAT is enabled.
[[nodiscard]]
node_view operator[] (std::wstring_view key) const noexcept
{
if (auto tbl = this->as_table())
return node_view{ tbl->get(key) };
return node_view{ nullptr };
}
#endif // TOML_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.
[[nodiscard]]
node_view operator[] (size_t index) const noexcept
{
if (auto arr = this->as_array())
return node_view{ arr->get(index) };
return node_view{ nullptr };
}
template <typename Char, typename T>
friend std::basic_ostream<Char>& operator << (std::basic_ostream<Char>&, const node_view<T>&);
};
template <typename T> node_view(const value<T>&) -> node_view<const node>;
node_view(const table&) -> node_view<const node>;
node_view(const array&) -> node_view<const node>;
template <typename T> node_view(value<T>&) -> node_view<node>;
node_view(table&) -> node_view<node>;
node_view(array&) -> node_view<node>;
template <typename T> node_view(const T*) -> node_view<const node>;
template <typename T> node_view(T*) -> node_view<node>;
/// \brief Prints the viewed node out to a stream.
template <typename Char, typename T>
inline std::basic_ostream<Char>& operator << (std::basic_ostream<Char>& os, const node_view<T>& nv)
{
if (nv.node_)
{
nv.node_->visit([&os](const auto& n)
{
os << n;
});
}
return os;
}
#if !defined(DOXYGEN) && !TOML_HEADER_ONLY
extern template class TOML_API node_view<node>;
extern template class TOML_API node_view<const node>;
extern template TOML_API std::ostream& operator << (std::ostream&, const node_view<node>&);
extern template TOML_API std::ostream& operator << (std::ostream&, const node_view<const node>&);
#define TOML_EXTERN(name, T) \
extern template TOML_API optional<T> node_view<node>::name<T>() const noexcept; \
extern template TOML_API optional<T> node_view<const node>::name<T>() const noexcept
TOML_EXTERN(value_exact, std::string_view);
TOML_EXTERN(value_exact, std::string);
TOML_EXTERN(value_exact, const char*);
TOML_EXTERN(value_exact, int64_t);
TOML_EXTERN(value_exact, double);
TOML_EXTERN(value_exact, date);
TOML_EXTERN(value_exact, time);
TOML_EXTERN(value_exact, date_time);
TOML_EXTERN(value_exact, bool);
TOML_EXTERN(value, std::string_view);
TOML_EXTERN(value, std::string);
TOML_EXTERN(value, const char*);
TOML_EXTERN(value, signed char);
TOML_EXTERN(value, signed short);
TOML_EXTERN(value, signed int);
TOML_EXTERN(value, signed long);
TOML_EXTERN(value, signed long long);
TOML_EXTERN(value, unsigned char);
TOML_EXTERN(value, unsigned short);
TOML_EXTERN(value, unsigned int);
TOML_EXTERN(value, unsigned long);
TOML_EXTERN(value, unsigned long long);
TOML_EXTERN(value, double);
TOML_EXTERN(value, float);
TOML_EXTERN(value, date);
TOML_EXTERN(value, time);
TOML_EXTERN(value, date_time);
TOML_EXTERN(value, bool);
#ifdef __cpp_lib_char8_t
TOML_EXTERN(value_exact, std::u8string_view);
TOML_EXTERN(value_exact, std::u8string);
TOML_EXTERN(value_exact, const char8_t*);
TOML_EXTERN(value, std::u8string_view);
TOML_EXTERN(value, std::u8string);
TOML_EXTERN(value, const char8_t*);
#endif
#if TOML_WINDOWS_COMPAT
TOML_EXTERN(value_exact, std::wstring);
TOML_EXTERN(value, std::wstring);
#endif
#undef TOML_EXTERN
#endif // !TOML_HEADER_ONLY
}
TOML_NAMESPACE_END
TOML_POP_WARNINGS // TOML_DISABLE_ARITHMETIC_WARNINGS