381 lines
15 KiB
C++
381 lines
15 KiB
C++
//# This file is a part of toml++ and is subject to the the terms of the MIT license.
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//# Copyright (c) 2019-2020 Mark Gillard <mark.gillard@outlook.com.au>
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//# See https://github.com/marzer/tomlplusplus/blob/master/LICENSE for the full license text.
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// SPDX-License-Identifier: MIT
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#pragma once
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#include "toml_table.h"
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#include "toml_array.h"
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#include "toml_value.h"
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namespace toml
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{
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TOML_PUSH_WARNINGS
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TOML_DISABLE_FLOAT_WARNINGS
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template <typename Char, typename T>
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inline std::basic_ostream<Char>& operator << (std::basic_ostream<Char>&, const node_view<T>&);
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/// \brief A view of a node.
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///
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/// \detail A node_view is like a std::optional<toml::node> with lots of toml-specific stuff built-in.
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/// It _may_ represent a node, and allows you to do many of the same operations that you'd do
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/// on nodes directly, as well as easily traversing the node tree by creating
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/// subviews (via node_view::operator[]). \cpp
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///
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/// auto tbl = toml::parse(R"(
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///
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/// title = "my hardware store"
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///
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/// [[products]]
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/// name = "Hammer"
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/// sku = 738594937
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/// keywords = [ "hammer", "construction", "build" ]
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///
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/// [[products]]
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/// name = "Nail"
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/// sku = 284758393
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/// color = "gray"
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///
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/// )"sv);
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///
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/// std::cout << tbl["title"] << std::endl;
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/// std::cout << tbl["products"][0]["name"] << std::endl;
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/// std::cout << tbl["products"][0]["keywords"] << std::endl;
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/// std::cout << tbl["products"][0]["keywords"][2] << std::endl;
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///
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/// tbl["products"][0]["keywords"].as_array()->push_back("heavy");
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/// std::cout << tbl["products"][0]["keywords"] << std::endl;
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/// std::cout << "has product[2]: "sv << !!tbl["products"][2] << std::endl;
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/// std::cout << "product[2]: "sv << tbl["products"][2] << std::endl;
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/// \ecpp
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///
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/// \out
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/// "my hardware store"
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/// "Hammer"
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/// [ "hammer", "construction", "build" ]
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/// "build"
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/// [ "hammer", "construction", "build", "heavy" ]
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/// has product[2]: false
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/// product[2]:
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/// \eout
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template <typename T>
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class TOML_API TOML_TRIVIAL_ABI node_view
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{
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public:
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using viewed_type = T;
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private:
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friend class toml::table;
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template <typename U> friend class toml::node_view;
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mutable viewed_type* node_ = nullptr;
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TOML_NODISCARD_CTOR
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node_view(viewed_type* node) noexcept
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: node_{ node }
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{}
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template <typename Func>
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static constexpr bool visit_is_nothrow
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= noexcept(std::declval<viewed_type*>()->visit(std::declval<Func&&>()));
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public:
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/// \brief Constructs an empty node view.
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TOML_NODISCARD_CTOR
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node_view() noexcept = default;
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/// \brief Returns true if the view references a node.
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[[nodiscard]] explicit operator bool() const noexcept { return node_ != nullptr; }
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/// \brief Returns the node that's being referenced by the view.
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[[nodiscard]] viewed_type* get() const noexcept { return node_; }
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/// \brief Returns the type identifier for the viewed node.
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[[nodiscard]] node_type type() const noexcept { return node_ ? node_->type() : node_type::none; }
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/// \brief Returns true if the viewed node is a toml::table.
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[[nodiscard]] bool is_table() const noexcept { return node_ && node_->is_table(); }
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/// \brief Returns true if the viewed node is a toml::array.
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[[nodiscard]] bool is_array() const noexcept { return node_ && node_->is_array(); }
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/// \brief Returns true if the viewed node is a toml::value<>.
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[[nodiscard]] bool is_value() const noexcept { return node_ && node_->is_value(); }
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/// \brief Returns true if the viewed node is a toml::value<string>.
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[[nodiscard]] bool is_string() const noexcept { return node_ && node_->is_string(); }
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/// \brief Returns true if the viewed node is a toml::value<int64_t>.
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[[nodiscard]] bool is_integer() const noexcept { return node_ && node_->is_integer(); }
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/// \brief Returns true if the viewed node is a toml::value<double>.
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[[nodiscard]] bool is_floating_point() const noexcept { return node_ && node_->is_floating_point(); }
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/// \brief Returns true if the viewed node is a toml::value<int64_t> or toml::value<double>.
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[[nodiscard]] bool is_number() const noexcept { return node_ && node_->is_number(); }
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/// \brief Returns true if the viewed node is a toml::value<bool>.
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[[nodiscard]] bool is_boolean() const noexcept { return node_ && node_->is_boolean(); }
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/// \brief Returns true if the viewed node is a toml::value<date>.
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[[nodiscard]] bool is_date() const noexcept { return node_ && node_->is_date(); }
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/// \brief Returns true if the viewed node is a toml::value<time>.
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[[nodiscard]] bool is_time() const noexcept { return node_ && node_->is_time(); }
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/// \brief Returns true if the viewed node is a toml::value<date_time>.
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[[nodiscard]] bool is_date_time() const noexcept { return node_ && node_->is_date_time(); }
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/// \brief Returns true if the viewed node is a toml::array that contains only tables.
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[[nodiscard]] bool is_array_of_tables() const noexcept { return node_ && node_->is_array_of_tables(); }
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/// \brief Checks if this view references a node of a specific type.
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///
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/// \tparam U A TOML node or value type.
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///
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/// \returns Returns true if the viewed node is an instance of the specified type.
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///
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/// \see toml::node::is()
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template <typename U>
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[[nodiscard]]
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bool is() const noexcept
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{
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return node_ ? node_->template is<U>() : false;
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}
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/// \brief Gets a pointer to the viewed node as a more specific node type.
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///
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/// \tparam U The node type or TOML value type to cast to.
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///
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/// \returns A pointer to the node as the given type, or nullptr if it was a different type.
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///
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/// \see toml::node::as()
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template <typename U>
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[[nodiscard]]
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auto as() const noexcept
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{
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static_assert(
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impl::is_value_or_node<impl::unwrapped<U>>,
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"Template type parameter must be one of the basic value types, a toml::table, or a toml::array"
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);
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return node_ ? node_->template as<U>() : nullptr;
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}
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/// \brief Returns a pointer to the viewed node as a toml::table, if it is one.
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[[nodiscard]] auto as_table() const noexcept { return as<table>(); }
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/// \brief Returns a pointer to the viewed node as a toml::array, if it is one.
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[[nodiscard]] auto as_array() const noexcept { return as<array>(); }
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/// \brief Returns a pointer to the viewed node as a toml::value<string>, if it is one.
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[[nodiscard]] auto as_string() const noexcept { return as<string>(); }
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/// \brief Returns a pointer to the viewed node as a toml::value<int64_t>, if it is one.
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[[nodiscard]] auto as_integer() const noexcept { return as<int64_t>(); }
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/// \brief Returns a pointer to the viewed node as a toml::value<double>, if it is one.
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[[nodiscard]] auto as_floating_point() const noexcept { return as<double>(); }
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/// \brief Returns a pointer to the viewed node as a toml::value<bool>, if it is one.
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[[nodiscard]] auto as_boolean() const noexcept { return as<bool>(); }
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/// \brief Returns a pointer to the viewed node as a toml::value<date>, if it is one.
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[[nodiscard]] auto as_date() const noexcept { return as<date>(); }
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/// \brief Returns a pointer to the viewed node as a toml::value<time>, if it is one.
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[[nodiscard]] auto as_time() const noexcept { return as<time>(); }
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/// \brief Returns a pointer to the viewed node as a toml::value<date_time>, if it is one.
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[[nodiscard]] auto as_date_time() const noexcept { return as<date_time>(); }
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TOML_PUSH_WARNINGS
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TOML_DISABLE_INIT_WARNINGS
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/// \brief Gets the raw value contained by the referenced node.
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///
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/// \tparam U One of the TOML value types. Can also be a string_view.
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///
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/// \returns The underlying value if the node was a value of the matching type (or convertible to it), or an empty optional.
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///
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/// \see node::value()
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template <typename U>
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[[nodiscard]] optional<U> value() const noexcept
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{
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if (node_)
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return node_->template value<U>();
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return {};
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}
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TOML_POP_WARNINGS
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/// \brief Gets the raw value contained by the referenced node, or a default.
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///
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/// \tparam U Default value type. Must be (or be promotable to) one of the TOML value types.
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/// \param default_value The default value to return if the view did not reference a node,
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/// or if the node wasn't a value, wasn't the correct type, or no conversion was possible.
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///
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/// \returns The node's underlying value, or the default if the node wasn't a value, wasn't the
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/// correct type, or no conversion was possible.
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///
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/// \see node::value_or()
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template <typename U>
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[[nodiscard]] auto value_or(U&& default_value) const noexcept
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{
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using return_type = decltype(node_->value_or(std::forward<U>(default_value)));
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if (node_)
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return node_->value_or(std::forward<U>(default_value));
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return return_type{ std::forward<U>(default_value) };
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}
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/// \brief Invokes a visitor on the viewed node based on its concrete type.
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///
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/// \remarks Has no effect if the view does not reference a node.
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///
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/// \see node::visit()
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template <typename Func>
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decltype(auto) visit(Func&& visitor) const
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noexcept(visit_is_nothrow<Func&&>)
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{
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using return_type = decltype(node_->visit(std::forward<Func>(visitor)));
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if (node_)
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return node_->visit(std::forward<Func>(visitor));
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if constexpr (!std::is_void_v<return_type>)
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return return_type{};
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}
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/// \brief Gets a raw reference to the viewed node's underlying data.
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///
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/// \warning This function is dangerous if used carelessly and **WILL** break your code if the
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/// node_view didn't reference a node, or the chosen value type doesn't match the node's
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/// actual type. In debug builds an assertion will fire when invalid accesses are attempted: \cpp
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///
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/// auto tbl = toml::parse(R"(
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/// min = 32
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/// max = 45
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/// )"sv);
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///
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/// int64_t& min_ref = tbl["min"].ref<int64_t>(); // matching type
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/// double& max_ref = tbl["max"].ref<double>(); // mismatched type, hits assert()
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/// int64_t& foo_ref = tbl["foo"].ref<int64_t>(); // nonexistent key, hits assert()
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///
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/// \ecpp
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///
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/// \tparam U One of the TOML value types.
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///
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/// \returns A reference to the underlying data.
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template <typename U>
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[[nodiscard]] decltype(auto) ref() const noexcept
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{
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using type = impl::unwrapped<U>;
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static_assert(
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impl::is_value_or_node<type>,
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"Template type parameter must be one of the TOML value types, a toml::table, or a toml::array"
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);
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TOML_ASSERT(
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node_
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&& "toml::node_view::ref() called on a node_view that did not reference a node"
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);
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return node_->template ref<type>();
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}
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/// \brief Returns true if the viewed node is a table with the same contents as RHS.
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[[nodiscard]] friend bool operator == (const node_view& lhs, const table& rhs) noexcept
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{
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if (lhs.node_ == &rhs)
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return true;
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const auto tbl = lhs.as<table>();
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return tbl && *tbl == rhs;
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}
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TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&, const table&, )
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/// \brief Returns true if the viewed node is an array with the same contents as RHS.
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[[nodiscard]] friend bool operator == (const node_view& lhs, const array& rhs) noexcept
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{
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if (lhs.node_ == &rhs)
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return true;
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const auto arr = lhs.as<array>();
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return arr && *arr == rhs;
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}
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TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&, const array&, )
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/// \brief Returns true if the viewed node is a value with the same value as RHS.
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template <typename U>
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[[nodiscard]] friend bool operator == (const node_view& lhs, const toml::value<U>& rhs) noexcept
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{
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if (lhs.node_ == &rhs)
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return true;
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const auto val = lhs.as<U>();
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return val && *val == rhs;
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}
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TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&, const toml::value<U>&, template <typename U>)
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/// \brief Returns true if the viewed node is a value with the same value as RHS.
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template <typename U, typename = std::enable_if_t<impl::is_value_or_promotable<U>>>
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[[nodiscard]] friend bool operator == (const node_view& lhs, const U& rhs) noexcept
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{
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const auto val = lhs.as<impl::promoted<U>>();
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return val && *val == rhs;
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}
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TOML_ASYMMETRICAL_EQUALITY_OPS(
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const node_view&,
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const U&,
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template <typename U, typename = std::enable_if_t<impl::is_value_or_promotable<U>>>
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)
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/// \brief Returns true if the viewed node is an array with the same contents as the RHS initializer list.
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template <typename U>
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[[nodiscard]] friend bool operator == (const node_view& lhs, const std::initializer_list<U>& rhs) noexcept
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{
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const auto arr = lhs.as<array>();
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return arr && *arr == rhs;
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}
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TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&, const std::initializer_list<U>&, template <typename U>)
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/// \brief Returns true if the viewed node is an array with the same contents as the RHS vector.
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template <typename U>
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[[nodiscard]] friend bool operator == (const node_view& lhs, const std::vector<U>& rhs) noexcept
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{
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const auto arr = lhs.as<array>();
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return arr && *arr == rhs;
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}
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TOML_ASYMMETRICAL_EQUALITY_OPS(const node_view&, const std::vector<U>&, template <typename U>)
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/// \brief Returns a view of the selected subnode.
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///
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/// \param key The key of the node to retrieve
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///
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/// \returns A view of the selected node if this node represented a table and it contained a
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/// value at the given key, or an empty view.
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[[nodiscard]] node_view operator[] (string_view key) const noexcept
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{
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if (auto tbl = this->as_table())
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return { tbl->get(key) };
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return { nullptr };
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}
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/// \brief Returns a view of the selected subnode.
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///
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/// \param index The index of the node to retrieve
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///
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/// \returns A view of the selected node if this node represented an array and it contained a
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/// value at the given index, or an empty view.
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[[nodiscard]] node_view operator[] (size_t index) const noexcept
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{
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if (auto arr = this->as_array())
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return { arr->get(index) };
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return { nullptr };
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}
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template <typename Char, typename U>
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friend std::basic_ostream<Char>& operator << (std::basic_ostream<Char>&, const node_view<U>&);
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};
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/// \brief Prints the viewed node out to a stream.
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template <typename Char, typename T>
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TOML_EXTERNAL_LINKAGE
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std::basic_ostream<Char>& operator << (std::basic_ostream<Char>& os, const node_view<T>& nv)
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{
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if (nv.node_)
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{
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nv.node_->visit([&os](const auto& n)
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{
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os << n;
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});
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}
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return os;
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}
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#if !TOML_ALL_INLINE
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extern template class TOML_API node_view<node>;
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extern template class TOML_API node_view<const node>;
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extern template TOML_API std::ostream& operator << (std::ostream&, const node_view<node>&);
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extern template TOML_API std::ostream& operator << (std::ostream&, const node_view<const node>&);
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#endif
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TOML_POP_WARNINGS // TOML_DISABLE_FLOAT_WARNINGS
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}
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