Improved ParserStack state description

5 files changed, 584 insertions, 409 deletions

diff --git a/src/core/parser/ParserStack.cpp b/src/core/parser/ParserStack.cpp
index 02b142a..51a7a13 100644
--- a/src/core/parser/ParserStack.cpp
+++ b/src/core/parser/ParserStack.cpp
@@ -28,6 +28,10 @@ namespace ousia {
 
 /* A default handler */
 
+/**
+ * The DefaultHandler class is used in case no element handler is specified in
+ * the ParserState descriptor.
+ */
 class DefaultHandler : public Handler {
 public:
 	using Handler::Handler;
@@ -35,12 +39,12 @@ public:
 	void start(Variant::mapType &args) override {}
 
 	void end() override {}
-};
 
-static Handler *createDefaultHandler(const HandlerData &handlerData)
-{
-	return new DefaultHandler{handlerData};
-}
+	static Handler *create(const HandlerData &handlerData)
+	{
+		return new DefaultHandler{handlerData};
+	}
+};
 
 /* Class Handler */
 
@@ -54,40 +58,13 @@ void Handler::data(const std::string &data, int field)
 	}
 }
 
-void Handler::child(std::shared_ptr<Handler> handler)
-{
-	// Do nothing here
-}
-
-/* Class HandlerDescriptor */
-
-HandlerInstance HandlerDescriptor::create(const ParserContext &ctx,
-                                          std::string name, State parentState,
-                                          bool isChild, Variant::mapType &args,
-                                          const SourceLocation &location) const
-{
-	Handler *h;
-	HandlerData data{ctx, name, targetState, parentState, isChild, location};
-	if (ctor) {
-		h = ctor(data);
-	} else {
-		h = createDefaultHandler(data);
-	}
-
-	// Canonicalize the arguments
-	arguments.validateMap(args, ctx.getLogger(), true);
-
-	h->start(args);
-	return HandlerInstance(h, this);
-}
-
 /* Class ParserStack */
 
 /**
  * Returns an Exception that should be thrown when a currently invalid command
  * is thrown.
  */
-static LoggableException invalidCommand(const std::string &name,
+static LoggableException InvalidCommand(const std::string &name,
                                         const std::set<std::string> &expected)
 {
 	if (expected.empty()) {
@@ -104,47 +81,72 @@ static LoggableException invalidCommand(const std::string &name,
 	}
 }
 
-std::set<std::string> ParserStack::expectedCommands(State state)
+ParserStack::ParserStack(
+    ParserContext &ctx,
+    const std::multimap<std::string, const ParserState *> &states)
+    : ctx(ctx), states(states)
+{
+}
+
+std::set<std::string> ParserStack::expectedCommands(const ParserState &state)
 {
 	std::set<std::string> res;
-	for (const auto &v : handlers) {
-		if (v.second.parentStates.count(state)) {
+	for (const auto &v : states) {
+		if (v.second->parents.count(&state)) {
 			res.insert(v.first);
 		}
 	}
 	return res;
 }
 
+const ParserState &ParserStack::currentState()
+{
+	return stack.empty() ? ParserStates::None : stack.top()->state();
+}
+
+std::string ParserStack::currentCommandName()
+{
+	return stack.empty() ? std::string{} : stack.top()->name();
+}
+
 void ParserStack::start(std::string name, Variant::mapType &args,
                         const SourceLocation &location)
 {
 	// Fetch the current handler and the current state
-	const HandlerInstance *h = stack.empty() ? nullptr : &stack.top();
-	const State curState = currentState();
-	bool isChild = false;
+	ParserState const *currentState = &(this->currentState());
 
 	// Fetch the correct Handler descriptor for this
-	const HandlerDescriptor *descr = nullptr;
-	auto range = handlers.equal_range(name);
+	ParserState const *targetState = nullptr;
+	HandlerConstructor ctor = nullptr;
+	auto range = states.equal_range(name);
 	for (auto it = range.first; it != range.second; it++) {
-		const std::set<State> &parentStates = it->second.parentStates;
-		if (parentStates.count(curState) || parentStates.count(STATE_ALL)) {
-			descr = &(it->second);
+		const ParserStateSet &parents = it->second->parents;
+		if (parents.count(currentState) || parents.count(&ParserStates::All)) {
+			targetState = it->second;
+			ctor = targetState->elementHandler ? targetState->elementHandler
+			                                   : DefaultHandler::create;
 			break;
 		}
 	}
-	if (!descr && currentArbitraryChildren()) {
-		isChild = true;
-		descr = h->descr;
+
+	// Try to use the child handler if one was given
+	if (!targetState && currentState->childHandler) {
+		targetState = currentState;
+		ctor = targetState->childHandler;
 	}
 
 	// No descriptor found, throw an exception.
-	if (!descr) {
-		throw invalidCommand(name, expectedCommands(curState));
+	if (!targetState || !ctor) {
+		throw InvalidCommand(name, expectedCommands(*currentState));
 	}
 
+	// Canonicalize the arguments, allow additional arguments
+	targetState->arguments.validateMap(args, ctx.getLogger(), true);
+
 	// Instantiate the handler and call its start function
-	stack.emplace(descr->create(ctx, name, curState, isChild, args, location));
+	Handler *handler = ctor({ctx, name, *targetState, *currentState, location});
+	handler->start(args);
+	stack.emplace(handler);
 }
 
 void ParserStack::start(std::string name, const Variant::mapType &args,
@@ -162,17 +164,11 @@ void ParserStack::end()
 	}
 
 	// Remove the current HandlerInstance from the stack
-	HandlerInstance inst{stack.top()};
+	std::shared_ptr<Handler> inst{stack.top()};
 	stack.pop();
 
 	// Call the end function of the last Handler
-	inst.handler->end();
-
-	// Call the "child" function of the parent Handler in the stack
-	// (if one exists).
-	if (!stack.empty()) {
-		stack.top().handler->child(inst.handler);
-	}
+	inst->end();
 }
 
 void ParserStack::data(const std::string &data, int field)
@@ -183,7 +179,7 @@ void ParserStack::data(const std::string &data, int field)
 	}
 
 	// Pass the data to the current Handler instance
-	stack.top().handler->data(data, field);
+	stack.top()->data(data, field);
 }
 }
 
diff --git a/src/core/parser/ParserStack.hpp b/src/core/parser/ParserStack.hpp
index 031ce68..9bb080e 100644
--- a/src/core/parser/ParserStack.hpp
+++ b/src/core/parser/ParserStack.hpp
@@ -43,18 +43,11 @@
 
 #include "Parser.hpp"
 #include "ParserContext.hpp"
+#include "ParserState.hpp"
 
 namespace ousia {
 
 /**
- * The State type alias is used to
- */
-using State = int16_t;
-
-static const State STATE_ALL = -2;
-static const State STATE_NONE = -1;
-
-/**
  * Struct collecting all the data that is being passed to a Handler instance.
  */
 struct HandlerData {
@@ -72,18 +65,12 @@ struct HandlerData {
 	/**
 	 * Contains the current state of the state machine.
 	 */
-	const State state;
+	const ParserState &state;
 
 	/**
 	 * Contains the state of the state machine when the parent node was handled.
 	 */
-	const State parentState;
-
-	/**
-	 * Set to true if the tag that is being handled is not the tag that was
-	 * specified in the state machine but a child tag of that tag.
-	 */
-	const bool isChild;
+	const ParserState &parentState;
 
 	/**
 	 * Current source code location.
@@ -97,17 +84,14 @@ struct HandlerData {
 	 * @param name is the name of the string.
 	 * @param state is the state this handler was called for.
 	 * @param parentState is the state of the parent command.
-	 * @param isChild specifies whether this handler was called not for the
-	 * command that was specified in the state machine but a child command.
 	 * @param location is the location at which the handler is created.
 	 */
-	HandlerData(const ParserContext &ctx, std::string name, State state,
-	            State parentState, bool isChild, const SourceLocation location)
+	HandlerData(const ParserContext &ctx, std::string name, const ParserState &state,
+	            const ParserState &parentState, const SourceLocation location)
 	    : ctx(ctx),
 	      name(std::move(name)),
 	      state(state),
 	      parentState(parentState),
-	      isChild(isChild),
 	      location(location){};
 };
 
@@ -137,24 +121,68 @@ public:
 	 */
 	virtual ~Handler(){};
 
+	/**
+	 * Returns the command name for which the handler was created.
+	 *
+	 * @return a const reference at the command name.
+	 */
 	const std::string &name() { return handlerData.name; }
 
+	/**
+	 * Returns a reference at the ParserScope instance.
+	 *
+	 * @return a reference at the ParserScope instance.
+	 */
 	ParserScope &scope() { return handlerData.ctx.getScope(); }
 
+	/**
+	 * Returns a reference at the Manager instance which manages all nodes.
+	 *
+	 * @return a referance at the Manager instance.
+	 */
 	Manager &manager() { return handlerData.ctx.getManager(); }
 
+	/**
+	 * Returns a reference at the Logger instance used for logging error
+	 * messages.
+	 *
+	 * @return a reference at the Logger instance.
+	 */
 	Logger &logger() { return handlerData.ctx.getLogger(); }
 
+	/**
+	 * Returns a reference at the Project Node, representing the project into
+	 * which the file is currently being parsed.
+	 *
+	 * @return a referance at the Project Node.
+	 */
 	Rooted<Project> project() { return handlerData.ctx.getProject(); }
 
-	State state() { return handlerData.state; }
+	/**
+	 * Reference at the ParserState descriptor for which this Handler was
+	 * created.
+	 *
+	 * @return a const reference at the constructing ParserState descriptor.
+	 */
+	const ParserState &state() { return handlerData.state; }
 
-	State parentState() { return handlerData.parentState; }
+	/**
+	 * Reference at the ParserState descriptor of the parent state of the state
+	 * for which this Handler was created. Set to ParserStates::None if there
+	 * is no parent state.
+	 *
+	 * @return a const reference at the parent state of the constructing
+	 * ParserState descriptor.
+	 */
+	const ParserState &parentState() { return handlerData.parentState; }
 
+	/**
+	 * Returns the current location in the source file.
+	 *
+	 * @return the current location in the source file.
+	 */
 	SourceLocation location() { return handlerData.location; }
 
-	bool isChild() { return handlerData.isChild; }
-
 	/**
 	 * Called when the command that was specified in the constructor is
 	 * instanciated.
@@ -179,13 +207,6 @@ public:
 	 * depends on the format that is being parsed).
 	 */
 	virtual void data(const std::string &data, int field);
-
-	/**
-	 * Called whenever a direct child element was created and has ended.
-	 *
-	 * @param handler is a reference at the child Handler instance.
-	 */
-	virtual void child(std::shared_ptr<Handler> handler);
 };
 
 /**
@@ -198,99 +219,6 @@ public:
  */
 using HandlerConstructor = Handler *(*)(const HandlerData &handlerData);
 
-struct HandlerDescriptor;
-
-/**
- * Used internlly by StateStack to store Handler instances and parameters
- * from HandlerDescriptor that are not stored in the Handler instance
- * itself. Instances of the HandlerInstance class can be created using the
- * HandlerDescriptor "create" method.
- */
-struct HandlerInstance {
-	/**
-	 * Pointer at the actual handler instance.
-	 */
-	std::shared_ptr<Handler> handler;
-
-	/**
-	 * Pointer pointing at the descriptor from which the handler instance was
-	 * derived.
-	 */
-	const HandlerDescriptor *descr;
-
-	HandlerInstance(Handler *handler, const HandlerDescriptor *descr)
-	    : handler(handler), descr(descr)
-	{
-	}
-};
-
-/**
- * Used internally by StateStack to store the pushdown automaton
- * description.
- */
-struct HandlerDescriptor {
-	/**
-	 * The valid parent states.
-	 */
-	const std::set<State> parentStates;
-
-	/**
-	 * Pointer at a function which creates a new concrete Handler instance.
-	 */
-	const HandlerConstructor ctor;
-
-	/**
-	 * The target state for the registered handler.
-	 */
-	const State targetState;
-
-	/**
-	 * Set to true if this handler instance allows arbitrary children as
-	 * tags.
-	 */
-	const bool arbitraryChildren;
-
-	/**
-	 * Reference at an argument descriptor that should be used for validating
-	 * the incomming arguments.
-	 */
-	const Arguments arguments;
-
-	/**
-	 * Constructor of the HandlerDescriptor class.
-	 *
-	 * @param parentStates is a set of states in which a new handler of this
-	 * type may be instantiated.
-	 * @param ctor is a function pointer pointing at a function that
-	 * instantiates the acutal Handler instance.
-	 * @param targetState is the state the ParserStack switches to after
-	 * instantiating an in instance of the described Handler instances.
-	 * @param arbitraryChildren allows the Handler instance to handle any child
-	 * node.
-	 * @param arguments is an optional argument descriptor used for validating
-	 * the arguments that are passed to the instantiation of a handler function.
-	 */
-	HandlerDescriptor(std::set<State> parentStates, HandlerConstructor ctor,
-	                  State targetState, bool arbitraryChildren = false,
-	                  Arguments arguments = Arguments::None)
-	    : parentStates(std::move(parentStates)),
-	      ctor(ctor),
-	      targetState(targetState),
-	      arbitraryChildren(arbitraryChildren),
-	      arguments(std::move(arguments))
-	{
-	}
-
-	/**
-	 * Creates an instance of the concrete Handler class represented by the
-	 * HandlerDescriptor and calls its start function.
-	 */
-	HandlerInstance create(const ParserContext &ctx, std::string name,
-	                       State parentState, bool isChild,
-	                       Variant::mapType &args,
-	                       const SourceLocation &location) const;
-};
-
 /**
  * The ParserStack class is a pushdown automaton responsible for turning a
  * command stream into a tree of Node instances.
@@ -303,21 +231,15 @@ private:
 	ParserContext &ctx;
 
 	/**
-	 * Current location in the source code.
-	 */
-	SourceLocation location;
-
-	/**
 	 * Map containing all registered command names and the corresponding
-	 * handler
-	 * descriptor.
+	 * state descriptors.
 	 */
-	const std::multimap<std::string, HandlerDescriptor> &handlers;
+	const std::multimap<std::string, const ParserState *> &states;
 
 	/**
 	 * Internal stack used for managing the currently active Handler instances.
 	 */
-	std::stack<HandlerInstance> stack;
+	std::stack<std::shared_ptr<Handler>> stack;
 
 	/**
 	 * Used internally to get all expected command names for the given state
@@ -327,19 +249,18 @@ private:
 	 * @param state is the state for which all expected command names should be
 	 * returned.
 	 */
-	std::set<std::string> expectedCommands(State state);
+	std::set<std::string> expectedCommands(const ParserState &state);
 
 public:
 	/**
 	 * Creates a new instance of the ParserStack class.
 	 *
 	 * @param ctx is the parser context the parser stack is working on.
-	 * @param handlers is a map containing the command names and the
-	 * corresponding HandlerDescriptor instances.
+	 * @param states is a map containing the command names and pointers at the
+	 * corresponding ParserState instances.
 	 */
 	ParserStack(ParserContext &ctx,
-	            const std::multimap<std::string, HandlerDescriptor> &handlers)
-	    : ctx(ctx), handlers(handlers){};
+	            const std::multimap<std::string, const ParserState*> &states);
 
 	/**
 	 * Returns the state the ParserStack instance currently is in.
@@ -347,10 +268,7 @@ public:
 	 * @return the state of the currently active Handler instance or STATE_NONE
 	 * if no handler is on the stack.
 	 */
-	State currentState()
-	{
-		return stack.empty() ? STATE_NONE : stack.top().handler->state();
-	}
+	const ParserState &currentState();
 
 	/**
 	 * Returns the command name that is currently being handled.
@@ -358,26 +276,14 @@ public:
 	 * @return the name of the command currently being handled by the active
 	 * Handler instance or an empty string if no handler is currently active.
 	 */
-	std::string currentName()
-	{
-		return stack.empty() ? std::string{} : stack.top().handler->name();
-	}
-
-	/**
-	 * Returns whether the current command handler allows arbitrary children.
-	 *
-	 * @return true if the handler allows arbitrary children, false otherwise.
-	 */
-	bool currentArbitraryChildren()
-	{
-		return stack.empty() ? false : stack.top().descr->arbitraryChildren;
-	}
+	std::string currentCommandName();
 
 	/**
 	 * Function that should be called whenever a new command starts.
 	 *
 	 * @param name is the name of the command.
 	 * @param args is a map from strings to variants (argument name and value).
+	 * Note that the passed map will be modified.
 	 * @param location is the location in the source file at which the command
 	 * starts.
 	 */
@@ -392,7 +298,8 @@ public:
 	 * @param location is the location in the source file at which the command
 	 * starts.
 	 */
-	void start(std::string name, const Variant::mapType &args,
+	void start(std::string name,
+	           const Variant::mapType &args = Variant::mapType{},
 	           const SourceLocation &location = SourceLocation{});
 
 	/**
diff --git a/src/core/parser/ParserState.cpp b/src/core/parser/ParserState.cpp
new file mode 100644
index 0000000..825ab84
--- /dev/null
+++ b/src/core/parser/ParserState.cpp
@@ -0,0 +1,105 @@
+/*
+    Ousía
+    Copyright (C) 2014, 2015  Benjamin Paaßen, Andreas Stöckel
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "ParserState.hpp"
+
+namespace ousia {
+
+/* Class ParserState */
+
+ParserState::ParserState() : elementHandler(nullptr), childHandler(nullptr) {}
+
+ParserState::ParserState(ParserStateSet parents, Arguments arguments,
+                         RttiSet supportedTypes,
+                         HandlerConstructor elementHandler,
+                         HandlerConstructor childHandler)
+    : parents(parents),
+      arguments(arguments),
+      supportedTypes(supportedTypes),
+      elementHandler(elementHandler),
+      childHandler(childHandler)
+{
+}
+
+ParserState::ParserState(const ParserStateBuilder &builder)
+    : ParserState(builder.build())
+{
+}
+
+/* Class ParserStateBuilder */
+
+ParserStateBuilder &ParserStateBuilder::copy(const ParserState &state)
+{
+	this->state = state;
+	return *this;
+}
+
+ParserStateBuilder &ParserStateBuilder::parent(const ParserState *parent)
+{
+	state.parents.insert(parent);
+	return *this;
+}
+
+ParserStateBuilder &ParserStateBuilder::parents(const ParserStateSet &parents)
+{
+	state.parents.insert(parents.begin(), parents.end());
+	return *this;
+}
+
+ParserStateBuilder &ParserStateBuilder::arguments(const Arguments &arguments)
+{
+	state.arguments = arguments;
+	return *this;
+}
+
+ParserStateBuilder &ParserStateBuilder::supportedType(const Rtti *type)
+{
+	state.supportedTypes.insert(type);
+	return *this;
+}
+
+ParserStateBuilder &ParserStateBuilder::supportedTypes(const RttiSet &types)
+{
+	state.supportedTypes.insert(types.begin(), types.end());
+	return *this;
+}
+
+ParserStateBuilder &ParserStateBuilder::elementHandler(
+    HandlerConstructor elementHandler)
+{
+	state.elementHandler = elementHandler;
+	return *this;
+}
+
+ParserStateBuilder &ParserStateBuilder::childHandler(
+    HandlerConstructor childHandler)
+{
+	state.childHandler = childHandler;
+	return *this;
+}
+
+const ParserState &ParserStateBuilder::build() const { return state; }
+
+/* Constant initializations */
+
+namespace ParserStates {
+const ParserState All;
+const ParserState None;
+}
+}
+
diff --git a/src/core/parser/ParserState.hpp b/src/core/parser/ParserState.hpp
new file mode 100644
index 0000000..6b7182d
--- /dev/null
+++ b/src/core/parser/ParserState.hpp
@@ -0,0 +1,254 @@
+/*
+    Ousía
+    Copyright (C) 2014, 2015  Benjamin Paaßen, Andreas Stöckel
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/**
+ * @file ParserState.hpp
+ *
+ * Defines the ParserState class used within the ParserStack pushdown
+ * automaton and the ParserStateBuilder class for convenient construction of
+ * such classes.
+ *
+ * @author Andreas Stöckel (astoecke@techfak.uni-bielefeld.de)
+ */
+
+#ifndef _OUSIA_PARSER_STATE_HPP_
+#define _OUSIA_PARSER_STATE_HPP_
+
+#include <unordered_set>
+
+#include <core/common/Rtti.hpp>
+#include <core/common/Argument.hpp>
+
+namespace ousia {
+
+// Forward declarations
+class ParserStateBuilder;
+class ParserState;
+class HandlerData;
+class Handler;
+using HandlerConstructor = Handler *(*)(const HandlerData &handlerData);
+
+/**
+ * Set of pointers of parser states -- used for specifying a set of parent
+ * states.
+ */
+using ParserStateSet = std::unordered_set<const ParserState *>;
+
+/**
+ * Class used for the complete specification of a ParserState. Stores possible
+ * parent states, state handlers and arguments to be passed to that state.
+ */
+struct ParserState {
+	/**
+	 * Vector containing all possible parent states.
+	 */
+	ParserStateSet parents;
+
+	/**
+	 * Descriptor of the arguments that should be passed to the handler.
+	 */
+	Arguments arguments;
+
+	/**
+	 * Rtti types that are reported as supported when including or importing new
+	 * files while in this state. This value is passed as "supportedTypes" to
+	 * either the "import" or "include" function.
+	 */
+	RttiSet supportedTypes;
+
+	/**
+	 * Pointer at a function which creates a new concrete Handler instance for
+	 * the elements described by this state. May be nullptr in which case no
+	 * handler instance is created.
+	 */
+	HandlerConstructor elementHandler;
+
+	/**
+	 * Pointer at a function which creates a new concrete Handler instance for
+	 * all child elements for which no matching state is defined. May be nullptr
+	 * in which case no such elements are allowed.
+	 */
+	HandlerConstructor childHandler;
+
+	/**
+	 * Default constructor, initializes the handlers with nullptr.
+	 */
+	ParserState();
+
+	/**
+	 * Constructor taking values for all fields. Use the ParserStateBuilder
+	 * class for a more convenient construction of ParserState instances.
+	 *
+	 * @param parents is a vector containing all possible parent states.
+	 * @param arguments is a descriptor of arguments that should be passed to
+	 * the handler.
+	 * @param supportedTypes is a set of Rtti types that are reported as
+	 * supported when including or importing new files while in this state.
+	 * @param elementHandler is a pointer at a function which creates a new
+	 * concrete Handler instance for the elements described by this state. May
+	 * be nullptr in which case no handler instance is created.
+	 * @param childHandler is a pointer at a function which creates a new
+	 * concrete Handler instance for all child elements for which no matching
+	 * state is defined. May be nullptr in which case no such elements are
+	 * allowed.
+	 */
+	ParserState(ParserStateSet parents, Arguments arguments = Arguments{},
+	            RttiSet supportedTypes = RttiSet{},
+	            HandlerConstructor elementHandler = nullptr,
+	            HandlerConstructor childHandler = nullptr);
+
+	/**
+	 * Creates this ParserState from the given ParserStateBuilder instance.
+	 */
+	ParserState(const ParserStateBuilder &builder);
+};
+
+/**
+ * The ParserStateBuilder class is a class used for conveniently building new
+ * ParserState instances.
+ */
+class ParserStateBuilder {
+private:
+	/**
+	 * ParserState instance that is currently being built by the
+	 * ParserStateBuilder.
+	 */
+	ParserState state;
+
+public:
+	/**
+	 * Copies the ParserState instance and uses it as internal state. Overrides
+	 * all changes made by the ParserStateBuilder.
+	 *
+	 * @param state is the state that should be copied.
+	 * @return a reference at this ParserStateBuilder instance for method
+	 * chaining.
+	 */
+	ParserStateBuilder &copy(const ParserState &state);
+
+	/**
+	 * Adds the given ParserState to the list of supported parent states.
+	 *
+	 * @param parent is a pointer at the parent ParserState instance that should
+	 * be added as possible parent state.
+	 * @return a reference at this ParserStateBuilder instance for method
+	 * chaining.
+	 */
+	ParserStateBuilder &parent(const ParserState *parent);
+
+	/**
+	 * Adds the ParserState instances in the given ParserStateSet to the list of
+	 * supported parent states.
+	 *
+	 * @param parents is a set of pointers at ParserState instances that should
+	 * be added as possible parent states.
+	 * @return a reference at this ParserStateBuilder instance for method
+	 * chaining.
+	 */
+	ParserStateBuilder &parents(const ParserStateSet &parents);
+
+	/**
+	 * Sets the arguments that should be passed to the parser state handler to
+	 * those given as argument.
+	 *
+	 * @param arguments is the Arguments instance describing the Arguments that
+	 * should be parsed to a Handler for this ParserState.
+	 * @return a reference at this ParserStateBuilder instance for method
+	 * chaining.
+	 */
+	ParserStateBuilder &arguments(const Arguments &arguments);
+
+	/**
+	 * Adds the type described by the given Rtti pointer to the set of supported
+	 * types. These "supported types" describe a set of Rtti types that are
+	 * reported as supported when including or importing new files while in this
+	 * state.
+	 *
+	 * @param type is the type that should be added to the SupportedTypes list.
+	 * @return a reference at this ParserStateBuilder instance for method
+	 * chaining.
+	 */
+	ParserStateBuilder &supportedType(const Rtti *type);
+
+	/**
+	 * Adds the type described by the given Rtti pointer to the set of supported
+	 * types. These "supported types" describe a set of Rtti types that are
+	 * reported as supported when including or importing new files while in this
+	 * state.
+	 *
+	 * @param type is the type that should be added to the SupportedTypes list.
+	 * @return a reference at this ParserStateBuilder instance for method
+	 * chaining.
+	 */
+	ParserStateBuilder &supportedTypes(const RttiSet &types);
+
+	/**
+	 * Sets the constructor for the element handler. The constructor creates a
+	 * new concrete Handler instance for the elements described by this state.
+	 * May be nullptr in which case no handler instance is created (this is
+	 * the default value).
+	 *
+	 * @param elementHandler is the HandlerConstructor that should create a
+	 * new Handler instance.
+	 * @return a reference at this ParserStateBuilder instance for method
+	 * chaining.
+	 */
+	ParserStateBuilder &elementHandler(HandlerConstructor elementHandler);
+
+	/**
+	 * Sets the constructor for the child handler. The constructor creates a new
+	 * concrete Handler instance for all child elements for which no matching
+	 * state is defined. May be nullptr in which case no such elements are
+	 * allowed.
+	 *
+	 * @param childHandler is the HandlerConstructor that should point at the
+	 * constructor of the Handler instance for child elements.
+	 * @return a reference at this ParserStateBuilder instance for method
+	 * chaining.
+	 */
+	ParserStateBuilder &childHandler(HandlerConstructor childHandler);
+
+	/**
+	 * Returns a reference at the internal ParserState instance that was built
+	 * using the ParserStateBuilder.
+	 *
+	 * @return the built ParserState.
+	 */
+	const ParserState &build() const;
+};
+
+/**
+ * The ParserStates namespace contains all the global state constants used
+ * in the ParserStack class.
+ */
+namespace ParserStates {
+/**
+ * State representing all states.
+ */
+extern const ParserState All;
+
+/**
+ * State representing the initial state.
+ */
+extern const ParserState None;
+}
+
+}
+
+#endif /* _OUSIA_PARSER_STATE_HPP_ */
+
diff --git a/src/plugins/xml/XmlParser.cpp b/src/plugins/xml/XmlParser.cpp
index 3b7e37f..42620c3 100644
--- a/src/plugins/xml/XmlParser.cpp
+++ b/src/plugins/xml/XmlParser.cpp
@@ -72,54 +72,6 @@ public:
 	}
 };
 
-class HeadHandler : public Handler {
-public:
-	using Handler::Handler;
-
-	void start(Variant::mapType &args) override
-	{
-		// Make sure the "HEAD" node is actually allowed here
-		if (scope().getFlag(ParserFlag::POST_HEAD)) {
-			throw LoggableException{
-			    "\"head\" tag not allowed here, head was already specified or "
-			    "another command was given first",
-			    location()};
-		}
-
-		// Insert a new HeadNode instance
-		scope().push(new HeadNode{manager()});
-	}
-
-	void end() override
-	{
-		// Remove the HeadNode instance from the stack
-		scope().pop();
-		scope().setFlag(ParserFlag::POST_HEAD, true);
-	}
-
-	static Handler *create(const HandlerData &handlerData)
-	{
-		return new HeadHandler{handlerData};
-	}
-};
-
-class DisableHeadHandler : public Handler {
-public:
-	using Handler::Handler;
-
-	void start(Variant::mapType &args) override
-	{
-		scope().setFlag(ParserFlag::POST_HEAD, true);
-	}
-
-	void end() override {}
-
-	static Handler *create(const HandlerData &handlerData)
-	{
-		return new DisableHeadHandler{handlerData};
-	}
-};
-
 class TypesystemHandler : public Handler {
 public:
 	using Handler::Handler;
@@ -194,7 +146,7 @@ public:
 	}
 };
 
-class StructFieldHandler : public Handler {
+class TypesystemStructFieldHandler : public Handler {
 public:
 	using Handler::Handler;
 
@@ -238,11 +190,11 @@ public:
 
 	static Handler *create(const HandlerData &handlerData)
 	{
-		return new StructFieldHandler{handlerData};
+		return new TypesystemStructFieldHandler{handlerData};
 	}
 };
 
-class ConstantHandler : public Handler {
+class TypesystemConstantHandler : public Handler {
 public:
 	using Handler::Handler;
 
@@ -272,7 +224,7 @@ public:
 
 	static Handler *create(const HandlerData &handlerData)
 	{
-		return new ConstantHandler{handlerData};
+		return new TypesystemConstantHandler{handlerData};
 	}
 };
 
@@ -335,146 +287,106 @@ public:
 	}
 };
 
-/* Document structure */
-static const State STATE_DOCUMENT = 0;
-static const State STATE_DOCUMENT_HEAD = 1;
-
-/* Special commands */
-static const State STATE_IMPORT = 100;
-static const State STATE_INCLUDE = 101;
-
-/* Type system definitions */
-static const State STATE_TYPESYSTEM = 200;
-static const State STATE_TYPESYSTEM_HEAD = 201;
-static const State STATE_TYPES = 202;
-static const State STATE_CONSTANTS = 203;
-static const State STATE_CONSTANT = 204;
-static const State STATE_ENUM = 205;
-static const State STATE_STRUCT = 206;
-static const State STATE_FIELD = 207;
-
-/* Domain definitions */
-static const State STATE_DOMAIN = 300;
-static const State STATE_DOMAIN_HEAD = 301;
-static const State STATE_DOMAIN_STRUCTS = 302;
-static const State STATE_DOMAIN_STRUCT = 303;
-static const State STATE_DOMAIN_FIELDS = 304;
-static const State STATE_DOMAIN_FIELD = 305;
-static const State STATE_DOMAIN_PRIMITIVE_FIELD = 306;
-static const State STATE_DOMAIN_CHILDREN = 307;
-static const State STATE_DOMAIN_CHILD = 308;
-static const State STATE_DOMAIN_CHILD_REF = 309;
-static const State STATE_DOMAIN_PARENTS = 310;
-static const State STATE_DOMAIN_PARENT = 311;
-static const State STATE_DOMAIN_PARENT_FIELD = 312;
-static const State STATE_DOMAIN_PARENT_FIELD_REF = 313;
-static const State STATE_DOMAIN_ANNOTATIONS = 314;
-static const State STATE_DOMAIN_ANNOTATION = 315;
-
-static const std::multimap<std::string, HandlerDescriptor> XML_HANDLERS{
-    /* Document tags */
-    {"document",
-     {{STATE_NONE},
-      DocumentHandler::create,
-      STATE_DOCUMENT,
-      true,
-      {Argument::String("name", "")}}},
-    {"head", {{STATE_DOCUMENT}, HeadHandler::create, STATE_DOCUMENT_HEAD}},
-
-    /* Special commands */
-    {"import",
-     {{STATE_DOCUMENT_HEAD, STATE_TYPESYSTEM_HEAD}, nullptr, STATE_IMPORT}},
-    {"include", {{STATE_ALL}, nullptr, STATE_INCLUDE}},
-
-    /* Typesystem */
-    {"typesystem",
-     {{STATE_NONE, STATE_DOMAIN_HEAD},
-      TypesystemHandler::create,
-      STATE_TYPESYSTEM,
-      false,
-      {Argument::String("name")}}},
-    {"head", {{STATE_TYPESYSTEM}, HeadHandler::create, STATE_TYPESYSTEM}},
-    {"types", {{STATE_TYPESYSTEM}, DisableHeadHandler::create, STATE_TYPES}},
-    {"enum", {{STATE_TYPES}, nullptr, STATE_ENUM}},
-    {"struct",
-     {{STATE_TYPES},
-      TypesystemStructHandler::create,
-      STATE_STRUCT,
-      false,
-      {Argument::String("name"), Argument::String("parent", "")}}},
-    {"field",
-     {{STATE_STRUCT},
-      StructFieldHandler::create,
-      STATE_FIELD,
-      false,
-      {Argument::String("name"), Argument::String("type"),
-       Argument::Any("default", Variant::fromObject(nullptr))}}},
-    {"constants",
-     {{STATE_TYPESYSTEM}, DisableHeadHandler::create, STATE_CONSTANTS}},
-    {"constant",
-     {{STATE_CONSTANTS},
-      ConstantHandler::create,
-      STATE_CONSTANT,
-      false,
-      {Argument::String("name"), Argument::String("type"),
-       Argument::Any("value")}}},
-
-    /* Domain */
-    {"domain",
-     {{STATE_NONE, STATE_DOCUMENT_HEAD},
-      DomainHandler::create,
-      STATE_DOMAIN,
-      false,
-      {Argument::String("name")}}},
-    {"head",
-     {{STATE_DOMAIN},
-      HeadHandler::create,
-      STATE_DOMAIN_HEAD,
-      false,
-      Arguments{}}},
-    {"structs",
-     {{STATE_DOMAIN},
-      DisableHeadHandler::create,
-      STATE_DOMAIN_STRUCTS,
-      false,
-      Arguments{}}},
-    {"struct",
-     {{STATE_DOMAIN_STRUCTS},
-      DomainStructHandler::create,
-      STATE_DOMAIN_STRUCT,
-      false,
-      Arguments{Argument::String("name"),
-                Argument::Cardinality("cardinality", AnyCardinality),
-                Argument::Bool("isRoot", false),
-                Argument::Bool("transparent", false),
-                Argument::String("isa", "")}}},
-    {"fields",
-     {{STATE_DOMAIN_STRUCT, STATE_DOMAIN_ANNOTATIONS},
-     nullptr,
-     STATE_DOMAIN_FIELDS,
-     false,
-     Arguments{}}},
-    {"field",
-     {{STATE_DOMAIN_FIELDS},
-     nullptr,
-     STATE_DOMAIN_FIELD,
-     false,
-     Arguments{Argument::String("name", ""), Argument::Bool("isSubtree", false),
-               Argument::Bool("optional", false)}}},
-    {"primitive",
-     {{STATE_DOMAIN_FIELDS},
-     nullptr,
-     STATE_DOMAIN_PRIMITIVE_FIELD,
-     false,
-     Arguments{Argument::String("name", ""), Argument::Bool("optional", false),
-               Argument::String("type")}}},
-    {"annotations",
-     {{STATE_DOMAIN},
-      DisableHeadHandler::create,
-      STATE_DOMAIN_ANNOTATIONS,
-      false,
-      Arguments{}}}};
+class ImportHandler : public Handler {
+public:
+	using Handler::Handler;
+
+	void start(Variant::mapType &args) override
+	{
+		//	scope().import();
+	}
+
+	void end() override {}
+
+	static Handler *create(const HandlerData &handlerData)
+	{
+		return new ImportHandler{handlerData};
+	}
+};
 
+namespace ParserStates {
+/* Document states */
+static const ParserState Document =
+    ParserStateBuilder()
+        .parent(&None)
+        .elementHandler(DocumentHandler::create)
+        .arguments({Argument::String("name", "")});
+
+/* Domain states */
+static const ParserState Domain = ParserStateBuilder()
+                                      .parents({&None, &Document})
+                                      .elementHandler(DomainHandler::create)
+                                      .arguments({Argument::String("name")});
+static const ParserState DomainStruct =
+    ParserStateBuilder()
+        .parent(&Domain)
+        .elementHandler(DomainStructHandler::create)
+        .arguments({Argument::String("name"),
+                    Argument::Cardinality("cardinality", AnyCardinality),
+                    Argument::Bool("isRoot", false),
+                    Argument::Bool("transparent", false),
+                    Argument::String("isa", "")});
+static const ParserState DomainStructFields =
+    ParserStateBuilder().parent(&DomainStruct).arguments({});
+static const ParserState DomainStructField =
+    ParserStateBuilder().parent(&DomainStructFields).arguments(
+        {Argument::String("name", ""), Argument::Bool("isSubtree", false),
+         Argument::Bool("optional", false)});
+static const ParserState DomainStructPrimitive =
+    ParserStateBuilder().parent(&DomainStructFields).arguments(
+        {Argument::String("name", ""), Argument::Bool("optional", false),
+         Argument::String("type")});
+
+/* Typesystem states */
+static const ParserState Typesystem =
+    ParserStateBuilder()
+        .parents({&None, &Domain})
+        .elementHandler(TypesystemHandler::create)
+        .arguments({Argument::String("name", "")});
+static const ParserState TypesystemEnum =
+    ParserStateBuilder().parent(&Typesystem);
+static const ParserState TypesystemStruct =
+    ParserStateBuilder()
+        .parent(&Typesystem)
+        .elementHandler(TypesystemStructHandler::create)
+        .arguments({Argument::String("name"), Argument::String("parent", "")});
+static const ParserState TypesystemStructField =
+    ParserStateBuilder()
+        .parent(&TypesystemStruct)
+        .elementHandler(TypesystemStructFieldHandler::create)
+        .arguments({Argument::String("name"), Argument::String("type"),
+                    Argument::Any("default", Variant::fromObject(nullptr))});
+static const ParserState TypesystemConstant =
+    ParserStateBuilder()
+        .parent(&Typesystem)
+        .elementHandler(TypesystemConstantHandler::create)
+        .arguments({Argument::String("name"), Argument::String("type"),
+                    Argument::Any("value")});
+
+/* Special states for import and include */
+static const ParserState Import =
+    ParserStateBuilder().parents({&Document, &Typesystem, &Domain}).arguments(
+        {Argument::String("rel", ""), Argument::String("type", ""),
+         Argument::String("src")});
+static const ParserState Include = ParserStateBuilder().parent(&All).arguments(
+    {Argument::String("rel", ""), Argument::String("type", ""),
+     Argument::String("src")});
+
+static const std::multimap<std::string, const ParserState *> XmlStates{
+    {"document", &Document},
+    {"domain", &Domain},
+    {"struct", &DomainStruct},
+    {"fields", &DomainStructFields},
+    {"field", &DomainStructField},
+    {"primitive", &DomainStructPrimitive},
+    {"typesystem", &Typesystem},
+    {"enum", &TypesystemEnum},
+    {"struct", &TypesystemStruct},
+    {"field", &TypesystemStructField},
+    {"constant", &TypesystemConstant},
+    {"import", &Import},
+    {"include", &Include}};
+}
 /**
  * Wrapper class around the XML_Parser pointer which safely frees it whenever
  * the scope is left (e.g. because an exception was thrown).
@@ -572,6 +484,7 @@ static void xmlCharacterDataHandler(void *p, const XML_Char *s, int len)
 	XML_Parser parser = static_cast<XML_Parser>(p);
 	ParserStack *stack = static_cast<ParserStack *>(XML_GetUserData(parser));
 
+	syncLoggerPosition(parser);
 	const std::string data =
 	    Utils::trim(std::string{s, static_cast<size_t>(len)});
 	if (!data.empty()) {
@@ -588,7 +501,7 @@ void XmlParser::doParse(CharReader &reader, ParserContext &ctx)
 
 	// Create the parser stack instance and pass the reference to the state
 	// machine descriptor
-	ParserStack stack{ctx, XML_HANDLERS};
+	ParserStack stack{ctx, ParserStates::XmlStates};
 	XML_SetUserData(&p, &stack);
 	XML_UseParserAsHandlerArg(&p);