src/path_parser.hpp - CzechLight/netconf-cli - Gitiles

 /*
  * Copyright (C) 2020 CESNET, https://photonics.cesnet.cz/
  *
  * Written by Václav Kubernát <kubernat@cesnet.cz>
  *
 */

 #pragma once

 #include <boost/spirit/home/x3.hpp>
 #include "ast_handlers.hpp"
 #include "common_parsers.hpp"
 #include "leaf_data.hpp"

 namespace x3 = boost::spirit::x3;

 x3::rule<cdPath_class, dataPath_> const cdPath = "cdPath";
 x3::rule<getPath_class, decltype(get_::m_path)> const getPath = "getPath";
 x3::rule<rpcPath_class, dataPath_> const rpcPath = "rpcPath";
 x3::rule<presenceContainerPath_class, dataPath_> const presenceContainerPath = "presenceContainerPath";
 x3::rule<listInstancePath_class, dataPath_> const listInstancePath = "listInstancePath";
 x3::rule<leafListElementPath_class, dataPath_> const leafListElementPath = "leafListElementPath";
 x3::rule<initializePath_class, x3::unused_type> const initializePath = "initializePath";
 x3::rule<trailingSlash_class, TrailingSlash> const trailingSlash = "trailingSlash";
 x3::rule<absoluteStart_class, Scope> const absoluteStart = "absoluteStart";
 x3::rule<keyValue_class, keyValue_> const keyValue = "keyValue";
 x3::rule<key_identifier_class, std::string> const key_identifier = "key_identifier";
 x3::rule<listSuffix_class, std::vector<keyValue_>> const listSuffix = "listSuffix";
 x3::rule<createKeySuggestions_class, x3::unused_type> const createKeySuggestions = "createKeySuggestions";
 x3::rule<createValueSuggestions_class, x3::unused_type> const createValueSuggestions = "createValueSuggestions";
 x3::rule<suggestKeysEnd_class, x3::unused_type> const suggestKeysEnd = "suggestKeysEnd";
 x3::rule<class leafListValue_class, leaf_data_> const leafListValue = "leafListValue";

 enum class NodeParserMode {
     CompleteDataNode,
     IncompleteDataNode,
     CompletionsOnly,
     SchemaNode
 };

 template <auto>
 struct ModeToAttribute;
 template <>
 struct ModeToAttribute<NodeParserMode::CompleteDataNode> {
     using type = dataNode_;
 };
 template <>
 struct ModeToAttribute<NodeParserMode::IncompleteDataNode> {
     using type = dataNode_;
 };
 template <>
 struct ModeToAttribute<NodeParserMode::SchemaNode> {
     using type = schemaNode_;
 };
 // The CompletionsOnly attribute is dataNode_ only because of convenience:
 // having the same return type means we can get by without a ton of `if constexpr` stanzas.
 // So the code will still "parse data into the target attr" for simplicity.
 template <>
 struct ModeToAttribute<NodeParserMode::CompletionsOnly> {
     using type = dataNode_;
 };

 enum class CompletionMode {
     Schema,
     Data
 };

 template <NodeParserMode PARSER_MODE, CompletionMode COMPLETION_MODE>
 struct NodeParser : x3::parser<NodeParser<PARSER_MODE, COMPLETION_MODE>> {
     using attribute_type = typename ModeToAttribute<PARSER_MODE>::type;

     std::function<bool(const Schema&, const std::string& path)> m_filterFunction;

     NodeParser(const std::function<bool(const Schema&, const std::string& path)>& filterFunction)
         : m_filterFunction(filterFunction)
     {
     }

     // GCC complains that `end` isn't used when doing completions only
     // FIXME: GCC 10.1 doesn't emit a warning here. Remove [[maybe_unused]] when GCC 10 is available
     template <typename It, typename Ctx, typename RCtx, typename Attr>
     bool parse(It& begin, [[maybe_unused]] It end, Ctx const& ctx, RCtx& rctx, Attr& attr) const
     {
         std::string tableName;
         if constexpr (std::is_same<attribute_type, schemaNode_>()) {
             tableName = "schemaNode";
         } else {
             tableName = "dataNode";
         }
         x3::symbols<attribute_type> table(tableName);

         ParserContext& parserContext = x3::get<parser_context_tag>(ctx);
         parserContext.m_suggestions.clear();
         for (const auto& child : parserContext.m_schema.availableNodes(parserContext.currentSchemaPath(), Recursion::NonRecursive)) {
             attribute_type out;
             std::string parseString;
             if (child.first) {
                 out.m_prefix = module_{*child.first};
                 parseString = *child.first + ":";
             }
             parseString += child.second;

             if (!m_filterFunction(parserContext.m_schema, joinPaths(pathToSchemaString(parserContext.currentSchemaPath(), Prefixes::Always), parseString))) {
                 continue;
             }

             switch (parserContext.m_schema.nodeType(parserContext.currentSchemaPath(), child)) {
                 case yang::NodeTypes::Container:
                 case yang::NodeTypes::PresenceContainer:
                     out.m_suffix = container_{child.second};
                     parserContext.m_suggestions.emplace(Completion{parseString + "/"});
                     break;
                 case yang::NodeTypes::Leaf:
                     out.m_suffix = leaf_{child.second};
                     parserContext.m_suggestions.emplace(Completion{parseString + " "});
                     break;
                 case yang::NodeTypes::List:
                     if constexpr (std::is_same<attribute_type, schemaNode_>()) {
                         out.m_suffix = list_{child.second};
                     } else {
                         out.m_suffix = listElement_{child.second, {}};
                     }

                     if constexpr (COMPLETION_MODE == CompletionMode::Schema) {
                         parserContext.m_suggestions.emplace(Completion{parseString + "/"});
                     } else {
                         parserContext.m_suggestions.emplace(Completion{parseString, "[", Completion::WhenToAdd::IfFullMatch});
                     }
                     break;
                 case yang::NodeTypes::LeafList:
                     if constexpr (std::is_same<attribute_type, schemaNode_>()) {
                         out.m_suffix = leafList_{child.second};
                     } else {
                         out.m_suffix = leafListElement_{child.second, {}};
                     }

                     if constexpr (COMPLETION_MODE == CompletionMode::Schema) {
                         parserContext.m_suggestions.emplace(Completion{parseString + "/"});
                     } else {
                         parserContext.m_suggestions.emplace(Completion{parseString, "[", Completion::WhenToAdd::IfFullMatch});
                     }
                     break;
                 case yang::NodeTypes::Rpc:
                     out.m_suffix = rpcNode_{child.second};
                     parserContext.m_suggestions.emplace(Completion{parseString + "/"});
                     break;
                 case yang::NodeTypes::Action:
                     out.m_suffix = actionNode_{child.second};
                     parserContext.m_suggestions.emplace(Completion{parseString + "/"});
                     break;
                 case yang::NodeTypes::AnyXml:
                 case yang::NodeTypes::Notification:
                     continue;
             }
             table.add(parseString, out);
             if (!child.first) {
                 auto topLevelModule = parserContext.currentSchemaPath().m_nodes.begin()->m_prefix;
                 out.m_prefix = topLevelModule;
                 table.add(topLevelModule->m_name + ":" + parseString, out);
             }
         }
         table.add("..", attribute_type{nodeup_{}});
         parserContext.m_completionIterator = begin;

         if constexpr (PARSER_MODE == NodeParserMode::CompletionsOnly) {
             return true;
         } else {
             It saveIter;
             // GCC complains that I assign saveIter because I use it only if NodeType is dataNode_
             // FIXME: GCC 10.1 doesn't emit a warning here. Make this unconditional when GCC 10 is available.
             if constexpr (std::is_same<attribute_type, dataNode_>()) {
                 saveIter = begin;
             }

             auto res = table.parse(begin, end, ctx, rctx, attr);

             if (std::holds_alternative<leaf_>(attr.m_suffix)) {
                 parserContext.m_tmpListKeyLeafPath.m_location = parserContext.currentSchemaPath();
                 ModuleNodePair node{attr.m_prefix.flat_map([](const auto& it) {
                                         return boost::optional<std::string>{it.m_name};
                                     }),
                                     std::get<leaf_>(attr.m_suffix).m_name};
                 parserContext.m_tmpListKeyLeafPath.m_node = node;
             }

             if constexpr (std::is_same<attribute_type, dataNode_>()) {
                 if (std::holds_alternative<listElement_>(attr.m_suffix)) {
                     parserContext.m_tmpListPath = parserContext.currentDataPath();
                     auto tmpList = list_{std::get<listElement_>(attr.m_suffix).m_name};
                     parserContext.m_tmpListPath.m_nodes.emplace_back(attr.m_prefix, tmpList);

                     res = listSuffix.parse(begin, end, ctx, rctx, std::get<listElement_>(attr.m_suffix).m_keys);

                     // FIXME: think of a better way to do this, that is, get rid of manual iterator reverting
                     if (!res) {
                         // If listSuffix didn't succeed, we check, if we allow incomplete nodes. If we do, then we replace listElement_ with list_.
                         // If we don't, we fail the whole symbol table.
                         if constexpr (PARSER_MODE == NodeParserMode::IncompleteDataNode) {
                             res = true;
                             attr.m_suffix = list_{std::get<listElement_>(attr.m_suffix).m_name};
                         } else {
                             begin = saveIter;
                         }
                     }
                 }

                 if (std::holds_alternative<leafListElement_>(attr.m_suffix)) {
                     parserContext.m_tmpListKeyLeafPath.m_location = parserContext.currentSchemaPath();
                     ModuleNodePair node{attr.m_prefix.flat_map([](const auto& it) {
                                             return boost::optional<std::string>{it.m_name};
                                         }),
                                         std::get<leafListElement_>(attr.m_suffix).m_name};
                     parserContext.m_tmpListKeyLeafPath.m_node = node;
                     res = leafListValue.parse(begin, end, ctx, rctx, std::get<leafListElement_>(attr.m_suffix).m_value);

                     if (!res) {
                         if constexpr (PARSER_MODE == NodeParserMode::IncompleteDataNode) {
                             res = true;
                             attr.m_suffix = leafList_{std::get<leafListElement_>(attr.m_suffix).m_name};
                         } else {
                             begin = saveIter;
                         }
                     }
                 }
             }

             if (res) {
                 parserContext.pushPathFragment(attr);
             }

             return res;
         }
     }
 };

 template <CompletionMode COMPLETION_MODE> using schemaNode = NodeParser<NodeParserMode::SchemaNode, COMPLETION_MODE>;
 template <CompletionMode COMPLETION_MODE> using dataNode = NodeParser<NodeParserMode::CompleteDataNode, COMPLETION_MODE>;
 template <CompletionMode COMPLETION_MODE> using incompleteDataNode = NodeParser<NodeParserMode::IncompleteDataNode, COMPLETION_MODE>;
 template <CompletionMode COMPLETION_MODE> using pathCompletions = NodeParser<NodeParserMode::CompletionsOnly, COMPLETION_MODE>;

 using AnyPath = boost::variant<schemaPath_, dataPath_>;

 enum class PathParserMode {
     AnyPath,
     DataPath,
     DataPathListEnd
 };

 template <>
 struct ModeToAttribute<PathParserMode::AnyPath> {
     using type = AnyPath;
 };

 template <>
 struct ModeToAttribute<PathParserMode::DataPath> {
     using type = dataPath_;
 };

 template <>
 struct ModeToAttribute<PathParserMode::DataPathListEnd> {
     using type = dataPath_;
 };

 template <PathParserMode PARSER_MODE, CompletionMode COMPLETION_MODE>
 struct PathParser : x3::parser<PathParser<PARSER_MODE, COMPLETION_MODE>> {
     using attribute_type = ModeToAttribute<PARSER_MODE>;
     std::function<bool(const Schema&, const std::string& path)> m_filterFunction;

     PathParser(const std::function<bool(const Schema&, const std::string& path)>& filterFunction = [](const auto&, const auto&) { return true; })
         : m_filterFunction(filterFunction)
     {
     }

     template <typename It, typename Ctx, typename RCtx, typename Attr>
     bool parse(It& begin, It end, Ctx const& ctx, RCtx& rctx, Attr& attr) const
     {
         initializePath.parse(begin, end, ctx, rctx, x3::unused);
         dataPath_ attrData;

         auto pathEnd = x3::rule<class PathEnd>{"pathEnd"} = &space_separator | x3::eoi;
         // absoluteStart has to be separate from the dataPath parser,
         // otherwise, if the "dataNode % '/'" parser fails, the begin iterator
         // gets reverted to before the starting slash.
         auto res = (-absoluteStart).parse(begin, end, ctx, rctx, attrData.m_scope);
         auto dataPath = x3::attr(attrData.m_scope)
             >> (dataNode<COMPLETION_MODE>{m_filterFunction} % '/' | pathEnd >> x3::attr(std::vector<dataNode_>{}))
             >> -trailingSlash;
         res = dataPath.parse(begin, end, ctx, rctx, attrData);

         // If we allow data paths with a list at the end, we just try to parse that separately.
         if constexpr (PARSER_MODE == PathParserMode::DataPathListEnd || PARSER_MODE == PathParserMode::AnyPath) {
             if (!res || !pathEnd.parse(begin, end, ctx, rctx, x3::unused)) {
                 dataNode_ attrNodeList;
                 auto hasListEnd = incompleteDataNode<COMPLETION_MODE>{m_filterFunction}.parse(begin, end, ctx, rctx, attrNodeList);
                 if (hasListEnd) {
                     attrData.m_nodes.emplace_back(attrNodeList);
                     // If the trailing slash matches, no more nodes are parsed. That means no more completion. So, I
                     // generate them manually, but only if we're in AnyPath mode, so, for example, inside an `ls`
                     // command. If we're in DataPathListEnd it doesn't make sense to parse put any more nodes after the
                     // final list.
                     if constexpr (PARSER_MODE == PathParserMode::AnyPath) {
                         res = (-(trailingSlash >> x3::omit[pathCompletions<COMPLETION_MODE>{m_filterFunction}])).parse(begin, end, ctx, rctx, attrData.m_trailingSlash);
                     } else {
                         res = (-trailingSlash).parse(begin, end, ctx, rctx, attrData.m_trailingSlash);
                     }
                 }
             }
         }

         attr = attrData;
         if constexpr (PARSER_MODE == PathParserMode::AnyPath) {
             // If our data path already has some listElement_ fragments, we can't parse rest of the path as a schema path
             auto hasLists = std::any_of(attrData.m_nodes.begin(), attrData.m_nodes.end(),
                 [] (const auto& node) { return std::holds_alternative<listElement_>(node.m_suffix); });
             // If parsing failed, or if there's more input we try parsing schema nodes.
             if (!hasLists) {
                 if (!res || !pathEnd.parse(begin, end, ctx, rctx, x3::unused)) {
                     // If dataPath parsed some nodes, they will be saved in `attrData`. We have to keep these.
                     schemaPath_ attrSchema = dataPathToSchemaPath(attrData);
                     auto schemaPath = schemaNode<COMPLETION_MODE>{m_filterFunction} % '/';
                     // The schemaPath parser continues where the dataPath parser ended.
                     res = schemaPath.parse(begin, end, ctx, rctx, attrSchema.m_nodes);
                     auto trailing = -trailingSlash >> pathEnd;
                     res = trailing.parse(begin, end, ctx, rctx, attrSchema.m_trailingSlash);
                     attr = attrSchema;
                 }
             }
         }
         return res;
     }
 };

 // Need to use these wrappers so that my PathParser class gets the proper
 // attribute. Otherwise, Spirit injects the attribute of the outer parser that
 // uses my PathParser.
 // Example grammar: anyPath | module.
 // The PathParser class would get a boost::variant as the attribute, but I
 // don't want to deal with that, so I use these wrappers to ensure the
 // attribute I want (and let Spirit deal with boost::variant).
 auto const anyPath = x3::rule<class anyPath_class, AnyPath>{"anyPath"} = PathParser<PathParserMode::AnyPath, CompletionMode::Schema>{};
 auto const dataPath = x3::rule<class dataPath_class, dataPath_>{"dataPath"} = PathParser<PathParserMode::DataPath, CompletionMode::Data>{};
 auto const dataPathListEnd = x3::rule<class dataPath_class, dataPath_>{"dataPath"} = PathParser<PathParserMode::DataPathListEnd, CompletionMode::Data>{};

 #if __clang__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Woverloaded-shift-op-parentheses"
 #endif

 struct SuggestLeafListEnd : x3::parser<SuggestLeafListEnd> {
     using attribute_type = x3::unused_type;
     template <typename It, typename Ctx, typename RCtx, typename Attr>
     bool parse(It& begin, It, Ctx const& ctx, RCtx&, Attr&) const
     {
         auto& parserContext = x3::get<parser_context_tag>(ctx);
         parserContext.m_completionIterator = begin;
         parserContext.m_suggestions = {Completion{"]"}};

         return true;
     }
 } const suggestLeafListEnd;

 auto const leafListValue_def =
     '[' >> leaf_data >> suggestLeafListEnd >> ']';

 auto const rest =
     x3::omit[x3::no_skip[+(x3::char_ - '/' - space_separator)]];

 auto const key_identifier_def =
     x3::lexeme[
         ((x3::alpha | char_("_")) >> *(x3::alnum | char_("_") | char_("-") | char_(".")))
     ];

 auto const createKeySuggestions_def =
     x3::eps;

 auto const createValueSuggestions_def =
     x3::eps;

 auto const suggestKeysEnd_def =
     x3::eps;

 auto const keyValue_def =
     key_identifier > '=' > createValueSuggestions > leaf_data;

 auto const keyValueWrapper =
     x3::no_skip['[' > createKeySuggestions > keyValue > suggestKeysEnd > ']'];

 // even though we don't allow no keys to be supplied, the star allows me to check which keys are missing
 auto const listSuffix_def =
     *keyValueWrapper;

 auto const list_def =
     node_identifier >> !char_('[');

 auto const absoluteStart_def =
     x3::omit['/'] >> x3::attr(Scope::Absolute);

 auto const trailingSlash_def =
     x3::omit['/'] >> x3::attr(TrailingSlash::Present);

 auto const filterConfigFalse = [](const Schema& schema, const std::string& path) {
     return schema.isConfig(path);
 };

 // A WritableOps value is injected through the `x3::with` with this tag (see usage of the tag). It controls whether
 // `config: false` data can be set with the `set` command. This is used by yang-cli because that tool needs modeling of
 // the full datastore, including the "read-only" data.
 struct writableOps_tag;

 PathParser<PathParserMode::DataPath, CompletionMode::Data> const dataPathFilterConfigFalse{filterConfigFalse};

 struct WritableLeafPath : x3::parser<WritableLeafPath> {
     using attribute_type = dataPath_;
     template <typename It, typename Ctx, typename RCtx, typename Attr>
     static bool parse(It& begin, It end, Ctx const& ctx, RCtx& rctx, Attr& attr)
     {
         bool res;
         if (x3::get<writableOps_tag>(ctx) == WritableOps::Yes) {
             res = dataPath.parse(begin, end, ctx, rctx, attr);
         } else {
             res = dataPathFilterConfigFalse.parse(begin, end, ctx, rctx, attr);
         }
         if (!res) {
             return false;
         }

         if (attr.m_nodes.empty() || !std::holds_alternative<leaf_>(attr.m_nodes.back().m_suffix)) {
             auto& parserContext = x3::get<parser_context_tag>(ctx);
             parserContext.m_errorMsg = "This is not a path to leaf.";
             return false;
         }

         return true;
     }

 } writableLeafPath;

 struct RpcActionPath : x3::parser<RpcActionPath> {
     using attribute_type = dataPath_;
     template <typename It, typename Ctx, typename RCtx, typename Attr>
     static bool parse(It& begin, It end, Ctx const& ctx, RCtx& rctx, Attr& attr)
     {
         bool res = dataPath.parse(begin, end, ctx, rctx, attr);
         if (!res) {
             return false;
         }

         if (attr.m_nodes.empty()
             || (!std::holds_alternative<rpcNode_>(attr.m_nodes.back().m_suffix) && !std::holds_alternative<actionNode_>(attr.m_nodes.back().m_suffix))) {
             auto& parserContext = x3::get<parser_context_tag>(ctx);
             parserContext.m_errorMsg = "This is not a path to an RPC/action.";
             return false;
         }

         return true;
     }
 };

 auto const rpcActionPath = as<dataPath_>[RpcActionPath()];

 auto const noRpcOrAction = [](const Schema& schema, const std::string& path) {
     auto nodeType = schema.nodeType(path);
     return nodeType != yang::NodeTypes::Rpc && nodeType != yang::NodeTypes::Action;
 };

 auto const getPath_def =
     PathParser<PathParserMode::DataPathListEnd, CompletionMode::Data>{noRpcOrAction} |
     (module >> "*");

 auto const cdPath_def =
     PathParser<PathParserMode::DataPath, CompletionMode::Data>{[] (const Schema& schema, const std::string& path) {
         return noRpcOrAction(schema, path) && schema.nodeType(path) != yang::NodeTypes::Leaf;
     }};

 auto const presenceContainerPath_def =
     dataPath;

 auto const listInstancePath_def =
     dataPath;

 auto const leafListElementPath_def =
     dataPath;

 // A "nothing" parser, which is used to indicate we tried to parse a path
 auto const initializePath_def =
     x3::eps;


 #if __clang__
 #pragma GCC diagnostic pop
 #endif

 BOOST_SPIRIT_DEFINE(keyValue)
 BOOST_SPIRIT_DEFINE(key_identifier)
 BOOST_SPIRIT_DEFINE(listSuffix)
 BOOST_SPIRIT_DEFINE(cdPath)
 BOOST_SPIRIT_DEFINE(getPath)
 BOOST_SPIRIT_DEFINE(presenceContainerPath)
 BOOST_SPIRIT_DEFINE(listInstancePath)
 BOOST_SPIRIT_DEFINE(leafListElementPath)
 BOOST_SPIRIT_DEFINE(initializePath)
 BOOST_SPIRIT_DEFINE(createKeySuggestions)
 BOOST_SPIRIT_DEFINE(createValueSuggestions)
 BOOST_SPIRIT_DEFINE(suggestKeysEnd)
 BOOST_SPIRIT_DEFINE(leafListValue)
 BOOST_SPIRIT_DEFINE(absoluteStart)
 BOOST_SPIRIT_DEFINE(trailingSlash)
	/*
	* Copyright (C) 2020 CESNET, https://photonics.cesnet.cz/
	*
	* Written by Václav Kubernát <kubernat@cesnet.cz>
	*
	*/

	#pragma once

	#include <boost/spirit/home/x3.hpp>
	#include "ast_handlers.hpp"
	#include "common_parsers.hpp"
	#include "leaf_data.hpp"

	namespace x3 = boost::spirit::x3;

	x3::rule<cdPath_class, dataPath_> const cdPath = "cdPath";
	x3::rule<getPath_class, decltype(get_::m_path)> const getPath = "getPath";
	x3::rule<rpcPath_class, dataPath_> const rpcPath = "rpcPath";
	x3::rule<presenceContainerPath_class, dataPath_> const presenceContainerPath = "presenceContainerPath";
	x3::rule<listInstancePath_class, dataPath_> const listInstancePath = "listInstancePath";
	x3::rule<leafListElementPath_class, dataPath_> const leafListElementPath = "leafListElementPath";
	x3::rule<initializePath_class, x3::unused_type> const initializePath = "initializePath";
	x3::rule<trailingSlash_class, TrailingSlash> const trailingSlash = "trailingSlash";
	x3::rule<absoluteStart_class, Scope> const absoluteStart = "absoluteStart";
	x3::rule<keyValue_class, keyValue_> const keyValue = "keyValue";
	x3::rule<key_identifier_class, std::string> const key_identifier = "key_identifier";
	x3::rule<listSuffix_class, std::vector<keyValue_>> const listSuffix = "listSuffix";
	x3::rule<createKeySuggestions_class, x3::unused_type> const createKeySuggestions = "createKeySuggestions";
	x3::rule<createValueSuggestions_class, x3::unused_type> const createValueSuggestions = "createValueSuggestions";
	x3::rule<suggestKeysEnd_class, x3::unused_type> const suggestKeysEnd = "suggestKeysEnd";
	x3::rule<class leafListValue_class, leaf_data_> const leafListValue = "leafListValue";

	enum class NodeParserMode {
	CompleteDataNode,
	IncompleteDataNode,
	CompletionsOnly,
	SchemaNode
	};

	template <auto>
	struct ModeToAttribute;
	template <>
	struct ModeToAttribute<NodeParserMode::CompleteDataNode> {
	using type = dataNode_;
	};
	template <>
	struct ModeToAttribute<NodeParserMode::IncompleteDataNode> {
	using type = dataNode_;
	};
	template <>
	struct ModeToAttribute<NodeParserMode::SchemaNode> {
	using type = schemaNode_;
	};
	// The CompletionsOnly attribute is dataNode_ only because of convenience:
	// having the same return type means we can get by without a ton of `if constexpr` stanzas.
	// So the code will still "parse data into the target attr" for simplicity.
	template <>
	struct ModeToAttribute<NodeParserMode::CompletionsOnly> {
	using type = dataNode_;
	};

	enum class CompletionMode {
	Schema,
	Data
	};

	template <NodeParserMode PARSER_MODE, CompletionMode COMPLETION_MODE>
	struct NodeParser : x3::parser<NodeParser<PARSER_MODE, COMPLETION_MODE>> {
	using attribute_type = typename ModeToAttribute<PARSER_MODE>::type;

	std::function<bool(const Schema&, const std::string& path)> m_filterFunction;

	NodeParser(const std::function<bool(const Schema&, const std::string& path)>& filterFunction)
	: m_filterFunction(filterFunction)
	{
	}

	// GCC complains that `end` isn't used when doing completions only
	// FIXME: GCC 10.1 doesn't emit a warning here. Remove [[maybe_unused]] when GCC 10 is available
	template <typename It, typename Ctx, typename RCtx, typename Attr>
	bool parse(It& begin, [[maybe_unused]] It end, Ctx const& ctx, RCtx& rctx, Attr& attr) const
	{
	std::string tableName;
	if constexpr (std::is_same<attribute_type, schemaNode_>()) {
	tableName = "schemaNode";
	} else {
	tableName = "dataNode";
	}
	x3::symbols<attribute_type> table(tableName);

	ParserContext& parserContext = x3::get<parser_context_tag>(ctx);
	parserContext.m_suggestions.clear();
	for (const auto& child : parserContext.m_schema.availableNodes(parserContext.currentSchemaPath(), Recursion::NonRecursive)) {
	attribute_type out;
	std::string parseString;
	if (child.first) {
	out.m_prefix = module_{*child.first};
	parseString = *child.first + ":";
	}
	parseString += child.second;

	if (!m_filterFunction(parserContext.m_schema, joinPaths(pathToSchemaString(parserContext.currentSchemaPath(), Prefixes::Always), parseString))) {
	continue;
	}

	switch (parserContext.m_schema.nodeType(parserContext.currentSchemaPath(), child)) {
	case yang::NodeTypes::Container:
	case yang::NodeTypes::PresenceContainer:
	out.m_suffix = container_{child.second};
	parserContext.m_suggestions.emplace(Completion{parseString + "/"});
	break;
	case yang::NodeTypes::Leaf:
	out.m_suffix = leaf_{child.second};
	parserContext.m_suggestions.emplace(Completion{parseString + " "});
	break;
	case yang::NodeTypes::List:
	if constexpr (std::is_same<attribute_type, schemaNode_>()) {
	out.m_suffix = list_{child.second};
	} else {
	out.m_suffix = listElement_{child.second, {}};
	}

	if constexpr (COMPLETION_MODE == CompletionMode::Schema) {
	parserContext.m_suggestions.emplace(Completion{parseString + "/"});
	} else {
	parserContext.m_suggestions.emplace(Completion{parseString, "[", Completion::WhenToAdd::IfFullMatch});
	}
	break;
	case yang::NodeTypes::LeafList:
	if constexpr (std::is_same<attribute_type, schemaNode_>()) {
	out.m_suffix = leafList_{child.second};
	} else {
	out.m_suffix = leafListElement_{child.second, {}};
	}

	if constexpr (COMPLETION_MODE == CompletionMode::Schema) {
	parserContext.m_suggestions.emplace(Completion{parseString + "/"});
	} else {
	parserContext.m_suggestions.emplace(Completion{parseString, "[", Completion::WhenToAdd::IfFullMatch});
	}
	break;
	case yang::NodeTypes::Rpc:
	out.m_suffix = rpcNode_{child.second};
	parserContext.m_suggestions.emplace(Completion{parseString + "/"});
	break;
	case yang::NodeTypes::Action:
	out.m_suffix = actionNode_{child.second};
	parserContext.m_suggestions.emplace(Completion{parseString + "/"});
	break;
	case yang::NodeTypes::AnyXml:
	case yang::NodeTypes::Notification:
	continue;
	}
	table.add(parseString, out);
	if (!child.first) {
	auto topLevelModule = parserContext.currentSchemaPath().m_nodes.begin()->m_prefix;
	out.m_prefix = topLevelModule;
	table.add(topLevelModule->m_name + ":" + parseString, out);
	}
	}
	table.add("..", attribute_type{nodeup_{}});
	parserContext.m_completionIterator = begin;

	if constexpr (PARSER_MODE == NodeParserMode::CompletionsOnly) {
	return true;
	} else {
	It saveIter;
	// GCC complains that I assign saveIter because I use it only if NodeType is dataNode_
	// FIXME: GCC 10.1 doesn't emit a warning here. Make this unconditional when GCC 10 is available.
	if constexpr (std::is_same<attribute_type, dataNode_>()) {
	saveIter = begin;
	}

	auto res = table.parse(begin, end, ctx, rctx, attr);

	if (std::holds_alternative<leaf_>(attr.m_suffix)) {
	parserContext.m_tmpListKeyLeafPath.m_location = parserContext.currentSchemaPath();
	ModuleNodePair node{attr.m_prefix.flat_map([](const auto& it) {
	return boost::optional<std::string>{it.m_name};
	}),
	std::get<leaf_>(attr.m_suffix).m_name};
	parserContext.m_tmpListKeyLeafPath.m_node = node;
	}

	if constexpr (std::is_same<attribute_type, dataNode_>()) {
	if (std::holds_alternative<listElement_>(attr.m_suffix)) {
	parserContext.m_tmpListPath = parserContext.currentDataPath();
	auto tmpList = list_{std::get<listElement_>(attr.m_suffix).m_name};
	parserContext.m_tmpListPath.m_nodes.emplace_back(attr.m_prefix, tmpList);

	res = listSuffix.parse(begin, end, ctx, rctx, std::get<listElement_>(attr.m_suffix).m_keys);

	// FIXME: think of a better way to do this, that is, get rid of manual iterator reverting
	if (!res) {
	// If listSuffix didn't succeed, we check, if we allow incomplete nodes. If we do, then we replace listElement_ with list_.
	// If we don't, we fail the whole symbol table.
	if constexpr (PARSER_MODE == NodeParserMode::IncompleteDataNode) {
	res = true;
	attr.m_suffix = list_{std::get<listElement_>(attr.m_suffix).m_name};
	} else {
	begin = saveIter;
	}
	}
	}

	if (std::holds_alternative<leafListElement_>(attr.m_suffix)) {
	parserContext.m_tmpListKeyLeafPath.m_location = parserContext.currentSchemaPath();
	ModuleNodePair node{attr.m_prefix.flat_map([](const auto& it) {
	return boost::optional<std::string>{it.m_name};
	}),
	std::get<leafListElement_>(attr.m_suffix).m_name};
	parserContext.m_tmpListKeyLeafPath.m_node = node;
	res = leafListValue.parse(begin, end, ctx, rctx, std::get<leafListElement_>(attr.m_suffix).m_value);

	if (!res) {
	if constexpr (PARSER_MODE == NodeParserMode::IncompleteDataNode) {
	res = true;
	attr.m_suffix = leafList_{std::get<leafListElement_>(attr.m_suffix).m_name};
	} else {
	begin = saveIter;
	}
	}
	}
	}

	if (res) {
	parserContext.pushPathFragment(attr);
	}

	return res;
	}
	}
	};

	template <CompletionMode COMPLETION_MODE> using schemaNode = NodeParser<NodeParserMode::SchemaNode, COMPLETION_MODE>;
	template <CompletionMode COMPLETION_MODE> using dataNode = NodeParser<NodeParserMode::CompleteDataNode, COMPLETION_MODE>;
	template <CompletionMode COMPLETION_MODE> using incompleteDataNode = NodeParser<NodeParserMode::IncompleteDataNode, COMPLETION_MODE>;
	template <CompletionMode COMPLETION_MODE> using pathCompletions = NodeParser<NodeParserMode::CompletionsOnly, COMPLETION_MODE>;

	using AnyPath = boost::variant<schemaPath_, dataPath_>;

	enum class PathParserMode {
	AnyPath,
	DataPath,
	DataPathListEnd
	};

	template <>
	struct ModeToAttribute<PathParserMode::AnyPath> {
	using type = AnyPath;
	};

	template <>
	struct ModeToAttribute<PathParserMode::DataPath> {
	using type = dataPath_;
	};

	template <>
	struct ModeToAttribute<PathParserMode::DataPathListEnd> {
	using type = dataPath_;
	};

	template <PathParserMode PARSER_MODE, CompletionMode COMPLETION_MODE>
	struct PathParser : x3::parser<PathParser<PARSER_MODE, COMPLETION_MODE>> {
	using attribute_type = ModeToAttribute<PARSER_MODE>;
	std::function<bool(const Schema&, const std::string& path)> m_filterFunction;

	PathParser(const std::function<bool(const Schema&, const std::string& path)>& filterFunction = [](const auto&, const auto&) { return true; })
	: m_filterFunction(filterFunction)
	{
	}

	template <typename It, typename Ctx, typename RCtx, typename Attr>
	bool parse(It& begin, It end, Ctx const& ctx, RCtx& rctx, Attr& attr) const
	{
	initializePath.parse(begin, end, ctx, rctx, x3::unused);
	dataPath_ attrData;

	auto pathEnd = x3::rule<class PathEnd>{"pathEnd"} = &space_separator \| x3::eoi;
	// absoluteStart has to be separate from the dataPath parser,
	// otherwise, if the "dataNode % '/'" parser fails, the begin iterator
	// gets reverted to before the starting slash.
	auto res = (-absoluteStart).parse(begin, end, ctx, rctx, attrData.m_scope);
	auto dataPath = x3::attr(attrData.m_scope)
	>> (dataNode<COMPLETION_MODE>{m_filterFunction} % '/' \| pathEnd >> x3::attr(std::vector<dataNode_>{}))
	>> -trailingSlash;
	res = dataPath.parse(begin, end, ctx, rctx, attrData);

	// If we allow data paths with a list at the end, we just try to parse that separately.
	if constexpr (PARSER_MODE == PathParserMode::DataPathListEnd \|\| PARSER_MODE == PathParserMode::AnyPath) {
	if (!res \|\| !pathEnd.parse(begin, end, ctx, rctx, x3::unused)) {
	dataNode_ attrNodeList;
	auto hasListEnd = incompleteDataNode<COMPLETION_MODE>{m_filterFunction}.parse(begin, end, ctx, rctx, attrNodeList);
	if (hasListEnd) {
	attrData.m_nodes.emplace_back(attrNodeList);
	// If the trailing slash matches, no more nodes are parsed. That means no more completion. So, I
	// generate them manually, but only if we're in AnyPath mode, so, for example, inside an `ls`
	// command. If we're in DataPathListEnd it doesn't make sense to parse put any more nodes after the
	// final list.
	if constexpr (PARSER_MODE == PathParserMode::AnyPath) {
	res = (-(trailingSlash >> x3::omit[pathCompletions<COMPLETION_MODE>{m_filterFunction}])).parse(begin, end, ctx, rctx, attrData.m_trailingSlash);
	} else {
	res = (-trailingSlash).parse(begin, end, ctx, rctx, attrData.m_trailingSlash);
	}
	}
	}
	}

	attr = attrData;
	if constexpr (PARSER_MODE == PathParserMode::AnyPath) {
	// If our data path already has some listElement_ fragments, we can't parse rest of the path as a schema path
	auto hasLists = std::any_of(attrData.m_nodes.begin(), attrData.m_nodes.end(),
	[] (const auto& node) { return std::holds_alternative<listElement_>(node.m_suffix); });
	// If parsing failed, or if there's more input we try parsing schema nodes.
	if (!hasLists) {
	if (!res \|\| !pathEnd.parse(begin, end, ctx, rctx, x3::unused)) {
	// If dataPath parsed some nodes, they will be saved in `attrData`. We have to keep these.
	schemaPath_ attrSchema = dataPathToSchemaPath(attrData);
	auto schemaPath = schemaNode<COMPLETION_MODE>{m_filterFunction} % '/';
	// The schemaPath parser continues where the dataPath parser ended.
	res = schemaPath.parse(begin, end, ctx, rctx, attrSchema.m_nodes);
	auto trailing = -trailingSlash >> pathEnd;
	res = trailing.parse(begin, end, ctx, rctx, attrSchema.m_trailingSlash);
	attr = attrSchema;
	}
	}
	}
	return res;
	}
	};

	// Need to use these wrappers so that my PathParser class gets the proper
	// attribute. Otherwise, Spirit injects the attribute of the outer parser that
	// uses my PathParser.
	// Example grammar: anyPath \| module.
	// The PathParser class would get a boost::variant as the attribute, but I
	// don't want to deal with that, so I use these wrappers to ensure the
	// attribute I want (and let Spirit deal with boost::variant).
	auto const anyPath = x3::rule<class anyPath_class, AnyPath>{"anyPath"} = PathParser<PathParserMode::AnyPath, CompletionMode::Schema>{};
	auto const dataPath = x3::rule<class dataPath_class, dataPath_>{"dataPath"} = PathParser<PathParserMode::DataPath, CompletionMode::Data>{};
	auto const dataPathListEnd = x3::rule<class dataPath_class, dataPath_>{"dataPath"} = PathParser<PathParserMode::DataPathListEnd, CompletionMode::Data>{};

	#if __clang__
	#pragma GCC diagnostic push
	#pragma GCC diagnostic ignored "-Woverloaded-shift-op-parentheses"
	#endif

	struct SuggestLeafListEnd : x3::parser<SuggestLeafListEnd> {
	using attribute_type = x3::unused_type;
	template <typename It, typename Ctx, typename RCtx, typename Attr>
	bool parse(It& begin, It, Ctx const& ctx, RCtx&, Attr&) const
	{
	auto& parserContext = x3::get<parser_context_tag>(ctx);
	parserContext.m_completionIterator = begin;
	parserContext.m_suggestions = {Completion{"]"}};

	return true;
	}
	} const suggestLeafListEnd;

	auto const leafListValue_def =
	'[' >> leaf_data >> suggestLeafListEnd >> ']';

	auto const rest =
	x3::omit[x3::no_skip[+(x3::char_ - '/' - space_separator)]];

	auto const key_identifier_def =
	x3::lexeme[
	((x3::alpha \| char_("_")) >> *(x3::alnum \| char_("_") \| char_("-") \| char_(".")))
	];

	auto const createKeySuggestions_def =
	x3::eps;

	auto const createValueSuggestions_def =
	x3::eps;

	auto const suggestKeysEnd_def =
	x3::eps;

	auto const keyValue_def =
	key_identifier > '=' > createValueSuggestions > leaf_data;

	auto const keyValueWrapper =
	x3::no_skip['[' > createKeySuggestions > keyValue > suggestKeysEnd > ']'];

	// even though we don't allow no keys to be supplied, the star allows me to check which keys are missing
	auto const listSuffix_def =
	*keyValueWrapper;

	auto const list_def =
	node_identifier >> !char_('[');

	auto const absoluteStart_def =
	x3::omit['/'] >> x3::attr(Scope::Absolute);

	auto const trailingSlash_def =
	x3::omit['/'] >> x3::attr(TrailingSlash::Present);

	auto const filterConfigFalse = [](const Schema& schema, const std::string& path) {
	return schema.isConfig(path);
	};

	// A WritableOps value is injected through the `x3::with` with this tag (see usage of the tag). It controls whether
	// `config: false` data can be set with the `set` command. This is used by yang-cli because that tool needs modeling of
	// the full datastore, including the "read-only" data.
	struct writableOps_tag;

	PathParser<PathParserMode::DataPath, CompletionMode::Data> const dataPathFilterConfigFalse{filterConfigFalse};

	struct WritableLeafPath : x3::parser<WritableLeafPath> {
	using attribute_type = dataPath_;
	template <typename It, typename Ctx, typename RCtx, typename Attr>
	static bool parse(It& begin, It end, Ctx const& ctx, RCtx& rctx, Attr& attr)
	{
	bool res;
	if (x3::get<writableOps_tag>(ctx) == WritableOps::Yes) {
	res = dataPath.parse(begin, end, ctx, rctx, attr);
	} else {
	res = dataPathFilterConfigFalse.parse(begin, end, ctx, rctx, attr);
	}
	if (!res) {
	return false;
	}

	if (attr.m_nodes.empty() \|\| !std::holds_alternative<leaf_>(attr.m_nodes.back().m_suffix)) {
	auto& parserContext = x3::get<parser_context_tag>(ctx);
	parserContext.m_errorMsg = "This is not a path to leaf.";
	return false;
	}

	return true;
	}

	} writableLeafPath;

	struct RpcActionPath : x3::parser<RpcActionPath> {
	using attribute_type = dataPath_;
	template <typename It, typename Ctx, typename RCtx, typename Attr>
	static bool parse(It& begin, It end, Ctx const& ctx, RCtx& rctx, Attr& attr)
	{
	bool res = dataPath.parse(begin, end, ctx, rctx, attr);
	if (!res) {
	return false;
	}

	if (attr.m_nodes.empty()
	\|\| (!std::holds_alternative<rpcNode_>(attr.m_nodes.back().m_suffix) && !std::holds_alternative<actionNode_>(attr.m_nodes.back().m_suffix))) {
	auto& parserContext = x3::get<parser_context_tag>(ctx);
	parserContext.m_errorMsg = "This is not a path to an RPC/action.";
	return false;
	}

	return true;
	}
	};

	auto const rpcActionPath = as<dataPath_>[RpcActionPath()];

	auto const noRpcOrAction = [](const Schema& schema, const std::string& path) {
	auto nodeType = schema.nodeType(path);
	return nodeType != yang::NodeTypes::Rpc && nodeType != yang::NodeTypes::Action;
	};

	auto const getPath_def =
	PathParser<PathParserMode::DataPathListEnd, CompletionMode::Data>{noRpcOrAction} \|
	(module >> "*");

	auto const cdPath_def =
	PathParser<PathParserMode::DataPath, CompletionMode::Data>{[] (const Schema& schema, const std::string& path) {
	return noRpcOrAction(schema, path) && schema.nodeType(path) != yang::NodeTypes::Leaf;
	}};

	auto const presenceContainerPath_def =
	dataPath;

	auto const listInstancePath_def =
	dataPath;

	auto const leafListElementPath_def =
	dataPath;

	// A "nothing" parser, which is used to indicate we tried to parse a path
	auto const initializePath_def =
	x3::eps;



	#if __clang__
	#pragma GCC diagnostic pop
	#endif

	BOOST_SPIRIT_DEFINE(keyValue)
	BOOST_SPIRIT_DEFINE(key_identifier)
	BOOST_SPIRIT_DEFINE(listSuffix)
	BOOST_SPIRIT_DEFINE(cdPath)
	BOOST_SPIRIT_DEFINE(getPath)
	BOOST_SPIRIT_DEFINE(presenceContainerPath)
	BOOST_SPIRIT_DEFINE(listInstancePath)
	BOOST_SPIRIT_DEFINE(leafListElementPath)
	BOOST_SPIRIT_DEFINE(initializePath)
	BOOST_SPIRIT_DEFINE(createKeySuggestions)
	BOOST_SPIRIT_DEFINE(createValueSuggestions)
	BOOST_SPIRIT_DEFINE(suggestKeysEnd)
	BOOST_SPIRIT_DEFINE(leafListValue)
	BOOST_SPIRIT_DEFINE(absoluteStart)
	BOOST_SPIRIT_DEFINE(trailingSlash)