refactored logger

9 files changed, 508 insertions, 454 deletions

diff --git a/src/core/common/CharReader.cpp b/src/core/common/CharReader.cpp
index 373c0c1..4bd81ed 100644
--- a/src/core/common/CharReader.cpp
+++ b/src/core/common/CharReader.cpp
@@ -83,7 +83,7 @@ Buffer::Buffer(const std::string &str)
 Buffer::~Buffer()
 {
 	// Make sure all cursors have been deleted
-	for (bool cursor_alive: alive) {
+	for (bool cursor_alive : alive) {
 		assert(!cursor_alive);
 	}
 }
@@ -516,7 +516,7 @@ CharReaderFork CharReader::fork()
 	return CharReaderFork(buffer, readCursor, peekCursor, coherent);
 }
 
-CharReader::Context CharReader::getContext(ssize_t maxSize)
+TextCursor::Context CharReader::getContext(ssize_t maxSize)
 {
 	// Clone the current read cursor
 	Buffer::CursorId cur = buffer->createCursor(readCursor.cursor);
@@ -612,7 +612,7 @@ CharReader::Context CharReader::getContext(ssize_t maxSize)
 	// Delete the newly created cursor
 	buffer->deleteCursor(cur);
 
-	return CharReader::Context{ss.str(), relPos, !foundBegin || tStart != start,
+	return TextCursor::Context{ss.str(), relPos, !foundBegin || tStart != start,
 	                           !foundEnd || tEnd != end};
 }
 
diff --git a/src/core/common/CharReader.hpp b/src/core/common/CharReader.hpp
index 3cbe4b4..7be5e08 100644
--- a/src/core/common/CharReader.hpp
+++ b/src/core/common/CharReader.hpp
@@ -32,6 +32,8 @@
 #include <memory>
 #include <vector>
 
+#include "TextCursor.hpp"
+
 namespace ousia {
 
 /**
@@ -359,52 +361,6 @@ class CharReaderFork;
  * of linebreaks and converts these to a single '\n'.
  */
 class CharReader {
-public:
-	/**
-	 * The context struct is used to represent the current context the char
-	 * reader is in. This context can for example be used when building error
-	 * messages.
-	 */
-	struct Context {
-		/**
-		 * Set to the content of the current line.
-		 */
-		std::string line;
-
-		/**
-		 * Relative position (in characters) within that line.
-		 */
-		size_t relPos;
-
-		/**
-		 * Set to true if the beginning of the line has been truncated (because
-		 * the reader position is too far away from the actual position of the
-		 * line).
-		 */
-		bool truncatedStart;
-
-		/**
-		 * Set to true if the end of the line has been truncated (because the
-		 * reader position is too far away from the actual end position of the
-		 * line.
-		 */
-		bool truncatedEnd;
-
-		Context()
-		    : line(), relPos(0), truncatedStart(false), truncatedEnd(false)
-		{
-		}
-
-		Context(std::string line, size_t relPos, bool truncatedStart,
-		        bool truncatedEnd)
-		    : line(std::move(line)),
-		      relPos(relPos),
-		      truncatedStart(truncatedStart),
-		      truncatedEnd(truncatedEnd)
-		{
-		}
-	};
-
 protected:
 	/**
 	 * Internally used cursor structure for managing the read and the peek
@@ -419,19 +375,20 @@ protected:
 		/**
 		 * Current line the cursor is in.
 		 */
-		uint32_t line;
+		TextCursor::PosType line;
 
 		/**
 		 * Current column the cursor is in.
 		 */
-		uint32_t column;
+		TextCursor::PosType column;
 
 		/**
 		 * Constructor of the Cursor class.
 		 *
 		 * @param cursor is the underlying cursor in the Buffer instance.
 		 */
-		Cursor(Buffer::CursorId cursor, size_t line, size_t column)
+		Cursor(Buffer::CursorId cursor, TextCursor::PosType line,
+		       TextCursor::PosType column)
 		    : cursor(cursor), line(line), column(column)
 		{
 		}
@@ -591,31 +548,35 @@ public:
 	bool atEnd() const { return buffer->atEnd(readCursor.cursor); }
 
 	/**
-	 * Returns the current line (starting with one).
-	 *
-	 * @return the current line number.
+	 * Returns the offset of the read cursor in bytes.
 	 */
-	uint32_t getLine() const { return readCursor.line; }
+	size_t getOffset() const { return buffer->offset(readCursor.cursor); }
 
 	/**
-	 * Returns the current column (starting with one).
-	 *
-	 * @return the current column number.
+	 * Returns the line number the read cursor currently is at.
 	 */
-	uint32_t getColumn() const { return readCursor.column; }
+	TextCursor::PosType getLine() const { return readCursor.line; }
 
 	/**
-	 * Returns the current byte offset of the read cursor.
-	 *
-	 * @return the byte position within the stream.
+	 * Returns the column the read cursor currently is at.
 	 */
-	size_t getOffset() const { return buffer->offset(readCursor.cursor); };
+	TextCursor::PosType getColumn() const { return readCursor.column; }
+
+	/**
+	 * Returns the current position of the read cursor (line and column).
+	 */
+	TextCursor::Position getPosition() const
+	{
+		return TextCursor::Position(getLine(), getColumn(), getOffset());
+	}
 
 	/**
 	 * Returns the line the read cursor currently is in, but at most the
 	 * given number of characters in the form of a Context structure.
+	 *
+	 * @param maxSize is the maximum length of the extracted context
 	 */
-	Context getContext(ssize_t maxSize);
+	TextCursor::Context getContext(ssize_t maxSize = 60);
 };
 
 /**
@@ -658,7 +619,6 @@ public:
 	 */
 	void commit();
 };
-
 }
 
 #endif /* _OUSIA_CHAR_READER_HPP_ */
diff --git a/src/core/common/Exceptions.cpp b/src/core/common/Exceptions.cpp
index d064f35..30c5626 100644
--- a/src/core/common/Exceptions.cpp
+++ b/src/core/common/Exceptions.cpp
@@ -25,21 +25,21 @@ namespace ousia {
 /* Class LoggableException */
 
 std::string LoggableException::formatMessage(const std::string &msg,
-                                             const std::string &file,
-                                             int line, int column)
+                                             const TextCursor::Position &pos,
+                                             const TextCursor::Context &ctx)
 {
 	std::stringstream ss;
 	ss << "error ";
-	if (!file.empty()) {
-		ss << "while processing \"" << file << "\" ";
-	}
-	if (line >= 0) {
-		ss << "at line " << line << ", ";
-		if (column >= 0) {
-			ss << "column " << column << " ";
+	if (pos.hasLine()) {
+		ss << "at line " << pos.line << ", ";
+		if (pos.hasColumn()) {
+			ss << "column " << pos.column << " ";
 		}
 	}
 	ss << "with message: " << msg;
+	if (ctx.valid()) {
+		ss << " in context \"" << ctx.text << "\"";
+	}
 	return ss.str();
 }
 }
diff --git a/src/core/common/Exceptions.hpp b/src/core/common/Exceptions.hpp
index 00d6106..443c176 100644
--- a/src/core/common/Exceptions.hpp
+++ b/src/core/common/Exceptions.hpp
@@ -27,6 +27,8 @@
 #ifndef _OUSIA_EXCEPTIONS_HPP_
 #define _OUSIA_EXCEPTIONS_HPP_
 
+#include "TextCursor.hpp"
+
 namespace ousia {
 
 /**
@@ -81,80 +83,81 @@ private:
 	 * reported to the runtime environment.
 	 */
 	static std::string formatMessage(const std::string &msg,
-	                                 const std::string &file, int line,
-	                                 int column);
+	                                 const TextCursor::Position &pos,
+	                                 const TextCursor::Context &ctx);
 
 public:
 	/**
-	 * Message describing the error that occured.
+	 * Reported error message.
 	 */
 	const std::string msg;
 
 	/**
-	 * Name of the file in which the error occured. May be empty.
+	 * Position in the document at which the exception occurred.
 	 */
-	const std::string file;
+	const TextCursor::Position pos;
 
 	/**
-	 * Line at which the exception occured. Negative values are ignored.
+	 * Context in the document text in which the exception occurred.
 	 */
-	const int line;
-
-	/**
-	 * Column at which the exception occured. Negative values are ignored.
-	 */
-	const int column;
+	const TextCursor::Context ctx;
 
 	/**
 	 * Constructor of the LoggableException class.
 	 *
 	 * @param msg contains the error message.
-	 * @param file provides the context the message refers to. May be empty.
-	 * @param line is the line in the above file the message refers to.
-	 * @param column is the column in the above file the message refers to.
+	 * @param pos is the position at which the error occured.
+	 * @param ctx describes the context in which the error occured.
 	 */
-	LoggableException(std::string msg, std::string file, int line = -1,
-	                  int column = -1)
-	    : OusiaException(formatMessage(msg, file, line, column)),
+	LoggableException(std::string msg,
+	                  TextCursor::Position pos = TextCursor::Position{},
+	                  TextCursor::Context ctx = TextCursor::Context{})
+	    : OusiaException(formatMessage(msg, pos, ctx)),
 	      msg(std::move(msg)),
-	      file(std::move(file)),
-	      line(line),
-	      column(column)
+	      pos(std::move(pos)),
+	      ctx(std::move(ctx))
 	{
 	}
 
 	/**
-	 * Constructor of the LoggableException class with empty file.
+	 * Constructor of the LoggableException class.
 	 *
 	 * @param msg contains the error message.
 	 * @param line is the line in the above file the message refers to.
 	 * @param column is the column in the above file the message refers to.
+	 * @param offs is the byte offset.
 	 */
-	LoggableException(std::string msg, int line = -1, int column = -1)
-	    : OusiaException(formatMessage(msg, "", line, column)),
-	      msg(std::move(msg)),
-	      line(line),
-	      column(column)
+	LoggableException(std::string msg, TextCursor::PosType line,
+	                  TextCursor::PosType column, size_t offs)
+	    : LoggableException(msg, TextCursor::Position(line, column, offs))
 	{
 	}
 
 	/**
-	 * Constructor of the LoggableException class with empty file and an
-	 * position object.
+	 * Constructor of LoggableException for arbitrary position objects.
 	 *
 	 * @param msg is the actual log message.
-	 * @param pos is a const reference to a variable which provides position
-	 * information.
+	 * @param pos is a reference to a variable with position and context data.
 	 */
 	template <class PosType>
-	LoggableException(std::string msg, const PosType &pos)
-	    : OusiaException(
-	          formatMessage(msg, "", pos.getLine(), pos.getColumn())),
-	      msg(std::move(msg)),
-	      line(pos.getLine()),
-	      column(pos.getColumn())
+	LoggableException(std::string msg, PosType &pos)
+	    : LoggableException(std::move(msg), pos.getPosition(), pos.getContext())
 	{
 	}
+
+	/**
+	 * Returns the position at which the exception occured in the text.
+	 *
+	 * @return the position descriptor.
+	 */
+	TextCursor::Position getPosition() const { return pos; }
+
+	/**
+	 * Returns the context in which the exception occured in the text.
+	 *
+	 * @return the context descriptor.
+	 */
+	TextCursor::Context getContext() const { return ctx; }
 };
 }
 
diff --git a/src/core/common/Logger.cpp b/src/core/common/Logger.cpp
index 17f55a6..913594f 100644
--- a/src/core/common/Logger.cpp
+++ b/src/core/common/Logger.cpp
@@ -23,50 +23,8 @@
 
 namespace ousia {
 
-/* Class Logger */
+/* Class Terminal */
 
-void Logger::log(Severity severity, const std::string &msg,
-                 const std::string &file, int line, int column)
-{
-	// Copy the current severity level
-	if (static_cast<int>(severity) > static_cast<int>(maxEncounteredSeverity)) {
-		maxEncounteredSeverity = severity;
-	}
-
-	// Call the actual log message function if the severity is larger or equal
-	// to the minimum severity
-	if (static_cast<int>(severity) >= static_cast<int>(minSeverity)) {
-		process(Message{severity, msg, file, line, column});
-	}
-}
-
-unsigned int Logger::pushFilename(const std::string &name)
-{
-	filenameStack.push(name);
-	return filenameStack.size();
-}
-
-unsigned int Logger::popFilename()
-{
-	filenameStack.pop();
-	return filenameStack.size();
-}
-
-void Logger::unwindFilenameStack(unsigned int pos)
-{
-	while (filenameStack.size() > pos && !filenameStack.empty()) {
-		filenameStack.pop();
-	}
-}
-
-/* Class TerminalLogger */
-
-/**
- * Small class used internally for formated terminal output using ANSI/VT100
- * escape codes on supported terminals.
- *
- * TODO: Deactivate if using windows or use the corresponding API function.
- */
 class Terminal {
 private:
 	/**
@@ -109,29 +67,49 @@ public:
 	}
 };
 
-void TerminalLogger::process(const Message &msg)
+
+/* Class TerminalLogger */
+
+/**
+ * Small class used internally for formated terminal output using ANSI/VT100
+ * escape codes on supported terminals.
+ *
+ * TODO: Deactivate if using windows or use the corresponding API function.
+ */
+
+std::string TerminalLogger::currentFilename()
+{
+	if (!files.empty()) {
+		return files.top().file;
+	}
+	return std::string{};
+}
+
+void TerminalLogger::processMessage(Message msg)
 {
 	Terminal t(useColor);
 
 	// Print the file name
-	if (msg.hasFile()) {
-		os << t.color(Terminal::WHITE, true) << msg.file << t.reset();
+	std::string filename = currentFilename();
+	bool hasFile = !filename.empty();
+	if (hasFile) {
+		os << t.color(Terminal::WHITE, true) << filename << t.reset();
 	}
 
 	// Print line and column number
-	if (msg.hasLine()) {
-		if (msg.hasFile()) {
+	if (msg.pos.hasLine()) {
+		if (hasFile) {
 			os << ':';
 		}
-		os << t.color(Terminal::WHITE, true) << msg.line
+		os << t.color(Terminal::WHITE, true) << msg.pos.line
 		   << t.reset();
-		if (msg.hasColumn()) {
-			os << ':' << msg.column;
+		if (msg.pos.hasColumn()) {
+			os << ':' << msg.pos.column;
 		}
 	}
 
 	// Print the optional seperator
-	if (msg.hasFile() || msg.hasLine()) {
+	if (hasFile || msg.pos.hasLine()) {
 		os << ": ";
 	}
 
@@ -156,6 +134,38 @@ void TerminalLogger::process(const Message &msg)
 
 	// Print the actual message
 	os << msg.msg << std::endl;
+
+	// Print the error message context if available
+	if (msg.ctx.valid()) {
+		size_t relPos = msg.ctx.relPos;
+		if (msg.ctx.truncatedStart) {
+			os << "[...] ";
+			relPos += 6;
+		}
+		os << msg.ctx.text;
+		if (msg.ctx.truncatedEnd) {
+			os << " [...]";
+		}
+		os << std::endl;
+		for (size_t i = 0; i < relPos; i++) {
+			os << ' ';
+		}
+		os << t.color(Terminal::GREEN) << '^' << t.reset() << std::endl;
+	}
+}
+
+size_t TerminalLogger::processPushFile(File file)
+{
+	files.push(file);
+	return files.size();
+}
+
+size_t TerminalLogger::processPopFile()
+{
+	files.pop();
+	return files.size();
 }
+
+
 }
 
diff --git a/src/core/common/Logger.hpp b/src/core/common/Logger.hpp
index e6b97f4..6366f9a 100644
--- a/src/core/common/Logger.hpp
+++ b/src/core/common/Logger.hpp
@@ -35,6 +35,7 @@
 #include <vector>
 
 #include "Exceptions.hpp"
+#include "TextCursor.hpp"
 
 namespace ousia {
 
@@ -90,6 +91,40 @@ static constexpr Severity DEFAULT_MIN_SEVERITY = Severity::DEBUG;
 class Logger {
 public:
 	/**
+	 * Describes an included file.
+	 */
+	struct File {
+		/**
+		 * Is the name of the file.
+		 */
+		std::string file;
+
+		/**
+		 * Position at which the file was included.
+		 */
+		TextCursor::Position pos;
+
+		/**
+		 * Context in which the file was included.
+		 */
+		TextCursor::Context ctx;
+
+		/**
+		 * Constructor of the File struct.
+		 *
+		 * @param file is the name of the included file.
+		 * @param pos is the position in the parent file, at which this file
+		 * was included.
+		 * @param ctx is the context in which the feil was included.
+		 */
+		File(std::string file, TextCursor::Position pos,
+		     TextCursor::Context ctx)
+		    : file(file), pos(pos), ctx(ctx)
+		{
+		}
+	};
+
+	/**
 	 * The message struct represents a single log message and all information
 	 * attached to it.
 	 */
@@ -105,80 +140,42 @@ public:
 		std::string msg;
 
 		/**
-		 * Refers to the file which provides the context for this error message.
-		 * May be empty.
+		 * Position in the text the message refers to.
 		 */
-		std::string file;
+		TextCursor::Position pos;
 
 		/**
-		 * Line in the above file the error message refers to. Ignored if
-		 * smaller than zero.
+		 * Context the message refers to.
 		 */
-		int line;
-
-		/**
-		 * Column in the above file the error message refers to. Ignored if
-		 * smaller than zero.
-		 */
-		int column;
+		TextCursor::Context ctx;
 
 		/**
 		 * Constructor of the Message struct.
 		 *
 		 * @param severity describes the message severity.
 		 * @param msg contains the actual message.
-		 * @param file provides the context the message refers to. May be empty.
 		 * @param line is the line in the above file the message refers to.
 		 * @param column is the column in the above file the message refers to.
 		 */
-		Message(Severity severity, std::string msg, std::string file, int line,
-		        int column)
+		Message(Severity severity, std::string msg, TextCursor::Position pos,
+		        TextCursor::Context ctx)
 		    : severity(severity),
 		      msg(std::move(msg)),
-		      file(std::move(file)),
-		      line(line),
-		      column(column){};
-
-		/**
-		 * Returns true if the file string is set.
-		 *
-		 * @return true if the file string is set.
-		 */
-		bool hasFile() const { return !file.empty(); }
-
-		/**
-		 * Returns true if the line is set.
-		 *
-		 * @return true if the line number is a non-negative integer.
-		 */
-		bool hasLine() const { return line >= 0; }
-
-		/**
-		 * Returns true if column and line are set (since a column has no
-		 * significance without a line number).
-		 *
-		 * @return true if line number and column number are non-negative
-		 * integers.
-		 */
-		bool hasColumn() const { return hasLine() && column >= 0; }
+		      pos(std::move(pos)),
+		      ctx(std::move(ctx)){};
 	};
 
 private:
 	/**
 	 * Minimum severity a log message should have before it is discarded.
 	 */
-	Severity minSeverity;
+	const Severity minSeverity;
 
 	/**
 	 * Maximum encountered log message severity.
 	 */
 	Severity maxEncounteredSeverity;
 
-	/**
-	 * Stack containing the current file names that have been processed.
-	 */
-	std::stack<std::string> filenameStack;
-
 protected:
 	/**
 	 * Function to be overriden by child classes to actually display or store
@@ -188,7 +185,23 @@ protected:
 	 * @param msg is an instance of the Message struct containing the data that
 	 * should be logged.
 	 */
-	virtual void process(const Message &msg){};
+	virtual void processMessage(Message msg) {}
+
+	/**
+	 * Called whenever a new file is pushed onto the stack.
+	 *
+	 * @param file is the file that should be pushed onto the stack.
+	 * @return the stack depth after the file has been pushed.
+	 */
+	virtual size_t processPushFile(File file) { return 0; }
+
+	/**
+	 * Called whenever a file is popped from the stack.
+	 *
+	 * @return the stack depth after the current file has been removed from the
+	 * stack.
+	 */
+	virtual size_t processPopFile() { return 0; }
 
 public:
 	/**
@@ -210,51 +223,30 @@ public:
 	virtual ~Logger(){};
 
 	/**
-	 * Logs the given message. Most generic log function.
-	 *
-	 * @param severity is the severity of the log message.
-	 * @param msg is the actual log message.
-	 * @param file is the name of the file the message refers to. May be empty.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
-	 */
-	void log(Severity severity, const std::string &msg, const std::string &file,
-	         int line = -1, int column = -1);
-
-	/**
 	 * Logs the given message. The file name is set to the topmost file name on
 	 * the file name stack.
 	 *
 	 * @param severity is the severity of the log message.
 	 * @param msg is the actual log message.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
+	 * @param pos is the position the log message refers to.
+	 * @param ctx describes the context of the log message.
 	 */
-	void log(Severity severity, const std::string &msg, int line = -1,
-	         int column = -1)
+	void log(Severity severity, std::string msg,
+	         TextCursor::Position pos = TextCursor::Position{},
+	         TextCursor::Context ctx = TextCursor::Context{})
 	{
-		log(severity, msg, currentFilename(), line, column);
-	}
-
-	/**
-	 * Logs the given message. The file name is set to the topmost file name on
-	 * the file name stack.
-	 *
-	 * @param severity is the severity of the log message.
-	 * @param msg is the actual log message.
-	 * @param pos is a const reference to a variable which provides position
-	 * information.
-	 * @tparam PosType is the actual type of pos and must implement a getLine
-	 * and getColumn function.
-	 */
-	template <class PosType>
-	void logAt(Severity severity, const std::string &msg, const PosType &pos)
-	{
-		log(severity, msg, pos.getLine(), pos.getColumn());
+		// Update the maximum encountered severity level
+		if (static_cast<int>(severity) >
+		    static_cast<int>(maxEncounteredSeverity)) {
+			maxEncounteredSeverity = severity;
+		}
+
+		// Only process the message if its severity is larger than the
+		// set minimum severity.
+		if (static_cast<int>(severity) >= static_cast<int>(minSeverity)) {
+			processMessage(Message{severity, std::move(msg), std::move(pos),
+			                       std::move(ctx)});
+		}
 	}
 
 	/**
@@ -264,278 +256,188 @@ public:
 	 */
 	void log(const LoggableException &ex)
 	{
-		log(Severity::ERROR, ex.msg,
-		    ex.file.empty() ? currentFilename() : ex.file, ex.line, ex.column);
-	}
-
-	/**
-	 * Logs a debug message. The file name is set to the topmost file name on
-	 * the file name stack.
-	 *
-	 * @param msg is the actual log message.
-	 * @param file is the name of the file the message refers to. May be empty.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
-	 */
-	void debug(const std::string &msg, const std::string &file, int line = -1,
-	           int column = -1)
-	{
-		log(Severity::DEBUG, msg, file, line, column);
-	}
-
-	/**
-	 * Logs a debug message. The file name is set to the topmost file name on
-	 * the file name stack.
-	 *
-	 * @param msg is the actual log message.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
-	 */
-	void debug(const std::string &msg, int line = -1, int column = -1)
-	{
-		debug(msg, currentFilename(), line, column);
+		log(Severity::ERROR, ex.msg, ex.getPosition(), ex.getContext());
 	}
 
 	/**
-	 * Logs a debug message. The file name is set to the topmost file name on
+	 * Logs the given message. The file name is set to the topmost file name on
 	 * the file name stack.
 	 *
 	 * @param severity is the severity of the log message.
 	 * @param msg is the actual log message.
-	 * @param pos is a const reference to a variable which provides position
-	 * information.
+	 * @param pos is a reference to a variable which provides position and
+	 * context information.
 	 */
 	template <class PosType>
-	void debugAt(const std::string &msg, const PosType &pos)
+	void logAt(Severity severity, std::string msg, PosType &pos)
 	{
-		debug(msg, pos.getLine(), pos.getColumn());
+		log(severity, std::move(msg), pos.getPosition(), pos.getContext());
 	}
 
 	/**
-	 * Logs a note. The file name is set to the topmost file name on
-	 * the file name stack.
+	 * Logs a debug message. Debug messages will be discarded if the software
+	 * is compiled in the release mode (with the NDEBUG flag).
 	 *
 	 * @param msg is the actual log message.
-	 * @param file is the name of the file the message refers to. May be empty.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
-	 */
-	void note(const std::string &msg, const std::string &file, int line = -1,
-	          int column = -1)
+	 * @param pos describes the position of the debug message.
+	 * @param ctx describes the context of the debug message.
+	 */
+	void debug(std::string msg,
+	           TextCursor::Position pos = TextCursor::Position{},
+	           TextCursor::Context ctx = TextCursor::Context{})
 	{
-		log(Severity::NOTE, msg, file, line, column);
+#ifndef NDEBUG
+		log(Severity::DEBUG, std::move(msg), std::move(pos), std::move(ctx));
+#endif
 	}
 
 	/**
-	 * Logs a note. The file name is set to the topmost file name on
-	 * the file name stack.
+	 * Logs a debug message. Debug messages will be discarded if the software
+	 * is compiled in the release mode.
 	 *
 	 * @param msg is the actual log message.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
+	 * @param pos is a reference to a variable which provides position and
+	 * context information.
 	 */
-	void note(const std::string &msg, int line = -1, int column = -1)
+	template<class PosType>
+	void debug(std::string msg, PosType &pos)
 	{
-		note(msg, currentFilename(), line, column);
+#ifndef NDEBUG
+		logAt(Severity::DEBUG, std::move(msg), pos);
+#endif
 	}
 
 	/**
-	 * Logs a note. The file name is set to the topmost file name on
-	 * the file name stack.
+	 * Logs a note.
 	 *
 	 * @param msg is the actual log message.
-	 * @param pos is a const reference to a variable which provides position
-	 * information.
+	 * @param pos describes the position of the note.
+	 * @param ctx describes the context of the note.
 	 */
-	template <class PosType>
-	void noteAt(const std::string &msg, const PosType &pos)
+	void note(std::string msg,
+	          TextCursor::Position pos = TextCursor::Position{},
+	          TextCursor::Context ctx = TextCursor::Context{})
 	{
-		note(msg, pos.getLine(), pos.getColumn());
+		log(Severity::NOTE, std::move(msg), std::move(pos), std::move(ctx));
 	}
 
 	/**
-	 * Logs a warning. The file name is set to the topmost file name on
-	 * the file name stack.
+	 * Logs a note.
 	 *
 	 * @param msg is the actual log message.
-	 * @param file is the name of the file the message refers to. May be empty.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
-	 */
-	void warning(const std::string &msg, const std::string &file, int line = -1,
-	             int column = -1)
+	 * @param pos is a reference to a variable which provides position and
+	 * context information.
+	 */
+	template<class PosType>
+	void note(std::string msg, PosType &pos)
 	{
-		log(Severity::WARNING, msg, file, line, column);
+		logAt(Severity::NOTE, std::move(msg), pos);
 	}
 
 	/**
-	 * Logs a warning. The file name is set to the topmost file name on
-	 * the file name stack.
+	 * Logs a warning.
 	 *
 	 * @param msg is the actual log message.
-	 * @param pos is a const reference to a variable which provides position
-	 * information.
+	 * @param pos describes the position of the warning.
+	 * @param ctx describes the context of the warning.
 	 */
-	template <class PosType>
-	void warningAt(const std::string &msg, const PosType &pos)
+	void warning(std::string msg,
+	             TextCursor::Position pos = TextCursor::Position{},
+	             TextCursor::Context ctx = TextCursor::Context{})
 	{
-		warning(msg, pos.getLine(), pos.getColumn());
+		log(Severity::WARNING, std::move(msg), std::move(pos), std::move(ctx));
 	}
 
 	/**
-	 * Logs a warning. The file name is set to the topmost file name on
-	 * the file name stack.
+	 * Logs a warning.
 	 *
 	 * @param msg is the actual log message.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
+	 * @param pos is a reference to a variable which provides position and
+	 * context information.
 	 */
-	void warning(const std::string &msg, int line = -1, int column = -1)
+	template<class PosType>
+	void warning(std::string msg, PosType &pos)
 	{
-		warning(msg, currentFilename(), line, column);
+		logAt(Severity::WARNING, std::move(msg), pos);
 	}
 
 	/**
-	 * Logs an error message. The file name is set to the topmost file name on
-	 * the file name stack.
+	 * Logs an error message.
 	 *
 	 * @param msg is the actual log message.
-	 * @param file is the name of the file the message refers to. May be empty.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
-	 */
-	void error(const std::string &msg, const std::string &file, int line = -1,
-	           int column = -1)
+	 * @param pos is the position at which the error occured.
+	 * @param ctx describes the context in which the error occured.
+	 */
+	void error(std::string msg,
+	           TextCursor::Position pos = TextCursor::Position{},
+	           TextCursor::Context ctx = TextCursor::Context{})
 	{
-		log(Severity::ERROR, msg, file, line, column);
+		log(Severity::ERROR, std::move(msg), std::move(pos), std::move(ctx));
 	}
 
 	/**
-	 * Logs an error message. The file name is set to the topmost file name on
-	 * the file name stack.
+	 * Logs an error message.
 	 *
 	 * @param msg is the actual log message.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
+	 * @param pos is a reference to a variable which provides position and
+	 * context information.
 	 */
-	void error(const std::string &msg, int line = -1, int column = -1)
+	template<class PosType>
+	void error(std::string msg, PosType &pos)
 	{
-		error(msg, currentFilename(), line, column);
+		logAt(Severity::ERROR, std::move(msg), pos);
 	}
 
 	/**
-	 * Logs an error message. The file name is set to the topmost file name on
-	 * the file name stack.
+	 * Logs a fatal error message.
 	 *
 	 * @param msg is the actual log message.
-	 * @param pos is a const reference to a variable which provides position
-	 * information.
+	 * @param pos is the position at which the error occured.
+	 * @param ctx describes the context in which the error occured.
 	 */
-	template <class PosType>
-	void errorAt(const std::string &msg, const PosType &pos)
+	void fatalError(std::string msg,
+	                TextCursor::Position pos = TextCursor::Position{},
+	                TextCursor::Context ctx = TextCursor::Context{})
 	{
-		error(msg, pos.getLine(), pos.getColumn());
+		log(Severity::FATAL_ERROR, std::move(msg), std::move(pos),
+		    std::move(ctx));
 	}
 
-	/**
-	 * Logs a fatal error. The file name is set to the topmost file name on
-	 * the file name stack.
-	 *
-	 * @param msg is the actual log message.
-	 * @param file is the name of the file the message refers to. May be empty.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
-	 */
-	void fatalError(const std::string &msg, const std::string &file,
-	                int line = -1, int column = -1)
-	{
-		log(Severity::FATAL_ERROR, msg, file, line, column);
-	}
 
 	/**
-	 * Logs a fatal error. The file name is set to the topmost file name on
-	 * the file name stack.
+	 * Logs a fatal error message.
 	 *
 	 * @param msg is the actual log message.
-	 * @param line is the line in the above file at which the error occured.
-	 * Ignored if negative.
-	 * @param column is the column in the above file at which the error occured.
-	 * Ignored if negative.
+	 * @param pos is a reference to a variable which provides position and
+	 * context information.
 	 */
-	void fatalError(const std::string &msg, int line = -1, int column = -1)
+	template<class PosType>
+	void fatalError(std::string msg, PosType &pos)
 	{
-		fatalError(msg, currentFilename(), line, column);
+		logAt(Severity::FATAL_ERROR, std::move(msg), pos);
 	}
 
 	/**
-	 * Logs a fatal error. The file name is set to the topmost file name on
-	 * the file name stack.
+	 * Pushes a new file name onto the internal filename stack.
 	 *
-	 * @param msg is the actual log message.
-	 * @param pos is a const reference to a variable which provides position
-	 * information.
+	 * @param name is the name of the file to be added to the stack.
+	 * @param pos is the position from which the new file is included.
+	 * @param ctx is the context in which the new file is included.
 	 */
-	template <class PosType>
-	void fatalErrorAt(const std::string &msg, const PosType &pos)
+	size_t pushFile(std::string name,
+	                TextCursor::Position pos = TextCursor::Position{},
+	                TextCursor::Context ctx = TextCursor::Context{})
 	{
-		fatalError(msg, pos.getLine(), pos.getColumn());
+		return processPushFile(
+		    File(std::move(name), std::move(pos), std::move(ctx)));
 	}
 
 	/**
-	 * Pushes a new file name onto the internal filename stack.
-	 *
-	 * @param name is the name of the file that should be added to the filename
-	 * stack.
-	 * @return the size of the filename stack. This number can be passed to the
-	 * "unwindFilenameStack" method in order to return the stack to state it was
-	 * in after this function has been called.
-	 */
-	unsigned int pushFilename(const std::string &name);
-
-	/**
 	 * Pops the filename from the internal filename stack.
 	 *
 	 * @return the current size of the filename stack.
 	 */
-	unsigned int popFilename();
-
-	/**
-	 * Pops elements from the filename stack while it has more elements than
-	 * the given number and the stack is non-empty.
-	 *
-	 * @param pos is the position the filename stack should be unwound to. Use
-	 * a number returned by pushFilename.
-	 */
-	void unwindFilenameStack(unsigned int pos);
-
-	/**
-	 * Returns the topmost filename from the internal filename stack.
-	 *
-	 * @return the topmost filename from the filename stack or an empty string
-	 * if the filename stack is empty.
-	 */
-	std::string currentFilename()
-	{
-		return filenameStack.empty() ? std::string{} : filenameStack.top();
-	}
+	size_t popFile() { return processPopFile(); }
 
 	/**
 	 * Returns the maximum severity that was encountered by the Logger but at
@@ -553,14 +455,6 @@ public:
 	 * @return the minimum severity.
 	 */
 	Severity getMinSeverity() { return minSeverity; }
-
-	/**
-	 * Sets the minimum severity. Messages with a smaller severity will be
-	 * discarded. Only new messages will be filtered according to the new value.
-	 *
-	 * @param severity is the minimum severity for new log messages.
-	 */
-	void setMinSeverity(Severity severity) { minSeverity = severity; }
 };
 
 /**
@@ -580,11 +474,20 @@ private:
 	 */
 	bool useColor;
 
-protected:
 	/**
-	 * Implements the process function and logs the messages to the output.
+	 * Stack used to keep the file references.
 	 */
-	void process(const Message &msg) override;
+	std::stack<File> files;
+
+	/**
+	 * The size of the stack the last time a file backtrace was printed.
+	 */
+	size_t lastFilePrinted = 0;
+
+protected:
+	void processMessage(Message msg) override;
+	size_t processPushFile(File file) override;
+	size_t processPopFile() override;
 
 public:
 	/**
@@ -602,6 +505,12 @@ public:
 	    : Logger(minSeverity), os(os), useColor(useColor)
 	{
 	}
+
+	/**
+	 * Returns the name of the topmost file.
+	 */
+	std::string currentFilename();
+
 };
 }
 
diff --git a/src/core/common/TextCursor.hpp b/src/core/common/TextCursor.hpp
new file mode 100644
index 0000000..2633345
--- /dev/null
+++ b/src/core/common/TextCursor.hpp
@@ -0,0 +1,168 @@
+/*
+    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/>.
+*/
+
+#ifndef _OUSIA_TEXT_CURSOR_HPP_
+#define _OUSIA_TEXT_CURSOR_HPP_
+
+namespace ousia {
+namespace TextCursor {
+
+/**
+ * Type used for representing line or column positions.
+ */
+using PosType = unsigned int;
+
+/**
+ * Struct representing a position within the text. A position is defined by a
+ * byte offset (which is always reproducable), a line number and a column
+ * number.
+ */
+struct Position {
+	/**
+	 * Current line, starting with one.
+	 */
+	PosType line;
+
+	/**
+	 * Current column, starting with one.
+	 */
+	PosType column;
+
+	/**
+	 * Current byte offset.
+	 */
+	size_t offs;
+
+	/**
+	 * Default constructor of the Position struct, initializes all memebers
+	 * with zero.
+	 */
+	Position() : line(0), column(0), offs(0) {}
+
+	/**
+	 * Creates a new Position struct with only a line and no column.
+	 *
+	 * @param line is the line number.
+	 * @param column is the column number.
+	 */
+	Position(PosType line) : line(line), column(0), offs(0) {}
+
+	/**
+	 * Creates a new Position struct with a line and column.
+	 *
+	 * @param line is the line number.
+	 * @param column is the column number.
+	 */
+	Position(PosType line, PosType column) : line(line), column(column), offs(0)
+	{
+	}
+
+	/**
+	 * Creates a new Position struct with a line, column and byte offset.
+	 *
+	 * @param line is the line number.
+	 * @param column is the column number.
+	 * @param offs is the byte offset.
+	 */
+	Position(PosType line, PosType column, size_t offs)
+	    : line(line), column(column), offs(offs)
+	{
+	}
+
+	/**
+	 * Returns true, if the line number is valid, false otherwise.
+	 *
+	 * @return true for valid line numbers.
+	 */
+	bool hasLine() const { return line > 0; }
+
+	/**
+	 * Returns true, if the column number is valid, false otherwise.
+	 *
+	 * @return true for valid column numbers.
+	 */
+	bool hasColumn() const { return column > 0; }
+};
+
+/**
+ * Represents the current context a CharReader is in. Used for building error
+ * messages.
+ */
+struct Context {
+	/**
+	 * Set to the content of the current line.
+	 */
+	std::string text;
+
+	/**
+	 * Relative position (in characters) within that line. May point to
+	 * locations beyond the text content.
+	 */
+	PosType relPos;
+
+	/**
+	 * Set to true if the beginning of the line has been truncated (because
+	 * the reader position is too far away from the actual position of the
+	 * line).
+	 */
+	bool truncatedStart;
+
+	/**
+	 * Set to true if the end of the line has been truncated (because the
+	 * reader position is too far away from the actual end position of the
+	 * line.
+	 */
+	bool truncatedEnd;
+
+	/**
+	 * Default constructor, initializes all members with zero values.
+	 */
+	Context() : text(), relPos(0), truncatedStart(false), truncatedEnd(false) {}
+
+	/**
+	 * Constructor of the Context class.
+	 *
+	 * @param text is the current line the text cursor is at.
+	 * @param relPos is the relative position of the text cursor within that
+	 * line.
+	 * @param truncatedStart specifies whether the text was truncated at the
+	 * beginning.
+	 * @param truncatedEnd specifies whether the text was truncated at the
+	 * end.
+	 */
+	Context(std::string text, size_t relPos, bool truncatedStart,
+	        bool truncatedEnd)
+	    : text(std::move(text)),
+	      relPos(relPos),
+	      truncatedStart(truncatedStart),
+	      truncatedEnd(truncatedEnd)
+	{
+	}
+
+	/**
+	 * Returns true the context text is not empty.
+	 *
+	 * @return true if the context is valid and e.g. should be printed.
+	 */
+	bool valid() const { return !text.empty(); }
+};
+}
+}
+
+#endif /* _OUSIA_TEXT_CURSOR_HPP_ */
+
diff --git a/src/core/common/VariantReader.cpp b/src/core/common/VariantReader.cpp
index e611842..a31a658 100644
--- a/src/core/common/VariantReader.cpp
+++ b/src/core/common/VariantReader.cpp
@@ -101,7 +101,7 @@ private:
 		// Check whether the given character is valid
 		int v = charValue(c);
 		if (v < 0 || v >= base) {
-			logger.errorAt(ERR_UNEXPECTED_CHAR, reader);
+			logger.error(ERR_UNEXPECTED_CHAR, reader);
 			return false;
 		}
 
@@ -121,7 +121,7 @@ private:
 
 		// Check for any overflows
 		if (a < 0 || n < 0 || d < 0 || e < 0) {
-			logger.errorAt(ERR_TOO_LARGE, reader);
+			logger.error(ERR_TOO_LARGE, reader);
 			return false;
 		}
 		return true;
@@ -203,7 +203,7 @@ bool Number::parse(CharReader &reader, Logger &logger,
 					case '-':
 						// Do not allow multiple minus signs
 						if (state == State::HAS_MINUS) {
-							logger.errorAt(ERR_UNEXPECTED_CHAR, reader);
+							logger.error(ERR_UNEXPECTED_CHAR, reader);
 							return false;
 						}
 						state = State::HAS_MINUS;
@@ -259,7 +259,7 @@ bool Number::parse(CharReader &reader, Logger &logger,
 					case 'e':
 					case 'E':
 						if (state == State::LEADING_POINT) {
-							logger.errorAt(ERR_UNEXPECTED_CHAR, reader);
+							logger.error(ERR_UNEXPECTED_CHAR, reader);
 							return false;
 						}
 						state = State::EXP_INIT;
@@ -276,7 +276,7 @@ bool Number::parse(CharReader &reader, Logger &logger,
 			case State::EXP_INIT:
 				if (c == '-') {
 					if (state == State::EXP_HAS_MINUS) {
-						logger.errorAt(ERR_UNEXPECTED_CHAR, reader);
+						logger.error(ERR_UNEXPECTED_CHAR, reader);
 						return false;
 					}
 					state = State::EXP_HAS_MINUS;
@@ -303,7 +303,7 @@ bool Number::parse(CharReader &reader, Logger &logger,
 	    state == State::EXP) {
 		return true;
 	}
-	logger.errorAt(ERR_UNEXPECTED_END, reader);
+	logger.error(ERR_UNEXPECTED_END, reader);
 	return false;
 }
 
@@ -322,7 +322,7 @@ template <class T>
 static std::pair<bool, T> error(CharReader &reader, Logger &logger,
                                 const char *err, T res)
 {
-	logger.errorAt(err, reader);
+	logger.error(err, reader);
 	return std::make_pair(false, std::move(res));
 }
 
@@ -410,7 +410,7 @@ std::pair<bool, std::string> VariantReader::parseString(
 						if (Utils::isNumeric(c)) {
 							// TODO: Parse octal 000 sequence
 						} else {
-							logger.errorAt(ERR_INVALID_ESCAPE, reader);
+							logger.error(ERR_INVALID_ESCAPE, reader);
 						}
 						break;
 				}
@@ -476,7 +476,7 @@ std::pair<bool, Variant::arrayType> VariantReader::parseArray(
 				} else if (!Utils::isWhitespace(c)) {
 					hadError = true;
 					state = STATE_RESYNC;
-					logger.errorAt(ERR_UNEXPECTED_CHAR, reader);
+					logger.error(ERR_UNEXPECTED_CHAR, reader);
 				}
 				reader.consumePeek();
 				break;
diff --git a/src/plugins/xml/XmlParser.cpp b/src/plugins/xml/XmlParser.cpp
index 9a7b4d8..824219a 100644
--- a/src/plugins/xml/XmlParser.cpp
+++ b/src/plugins/xml/XmlParser.cpp
@@ -204,11 +204,15 @@ Rooted<Node> XmlParser::parse(std::istream &is, ParserContext &ctx)
 
 		// Parse the data and handle any XML error
 		if (!XML_ParseBuffer(&p, bytesRead, bytesRead == 0)) {
-			const int line = XML_GetCurrentLineNumber(&p);
-			const int column = XML_GetCurrentColumnNumber(&p);
+			const TextCursor::PosType line =
+			    static_cast<TextCursor::PosType>(XML_GetCurrentLineNumber(&p));
+			const TextCursor::PosType column = static_cast<TextCursor::PosType>(
+			    XML_GetCurrentColumnNumber(&p));
+			const size_t offs = XML_GetCurrentByteIndex(&p);
 			const XML_Error code = XML_GetErrorCode(&p);
 			const std::string msg = std::string{XML_ErrorString(code)};
-			throw ParserException{"XML Syntax Error: " + msg, line, column};
+			throw ParserException{"XML Syntax Error: " + msg, line, column,
+			                      offs};
 		}
 
 		// Abort once there are no more bytes in the stream