Refactored logging interface.

app/main.cpp

@@ -47,7 +47,7 @@ int main(int argc, char **argv)
 	}
 	catch (const po::error &e)
 	{
-		context.logger.log(anthem::output::Priority::Error, e.what());
+		context.logger.log(anthem::output::Priority::Error) << e.what();
 		printHelp();
 		return EXIT_FAILURE;
 	}
@@ -74,7 +74,7 @@ int main(int argc, char **argv)
 		context.logger.setColorPolicy(anthem::output::ColorStream::ColorPolicy::Always);
 	else
 	{
-		context.logger.log(anthem::output::Priority::Error, ("unknown color policy “" + colorPolicyString + "”").c_str());
+		context.logger.log(anthem::output::Priority::Error) << "unknown color policy “" << colorPolicyString << "”";
 		context.logger.errorStream() << std::endl;
 		printHelp();
 		return EXIT_FAILURE;
@@ -89,7 +89,7 @@ int main(int argc, char **argv)
 	}
 	catch (const std::exception &e)
 	{
-		context.logger.log(anthem::output::Priority::Error, ("unknown log priorty “" + logPriorityString + "”").c_str());
+		context.logger.log(anthem::output::Priority::Error) << "unknown log priorty “" << logPriorityString << "”";
 		context.logger.errorStream() << std::endl;
 		printHelp();
 		return EXIT_FAILURE;
@@ -107,7 +107,7 @@ int main(int argc, char **argv)
 	}
 	catch (const std::exception &e)
 	{
-		context.logger.log(anthem::output::Priority::Error, e.what());
+		context.logger.log(anthem::output::Priority::Error) << e.what();
 		return EXIT_FAILURE;
 	}
 

include/anthem/StatementVisitor.h

@@ -39,8 +39,7 @@ struct StatementVisitor
 {
 	void visit(const Clingo::AST::Program &program, const Clingo::AST::Statement &statement, std::vector<ast::ScopedFormula> &, Context &context)
 	{
-		// TODO: refactor
-		context.logger.log(output::Priority::Debug, (std::string("[program] ") + program.name).c_str());
+		context.logger.log(output::Priority::Debug) << "[program] " << program.name;
 
 		if (!program.parameters.empty())
 			throwErrorAtLocation(statement.location, "program parameters currently unsupported", context);
@@ -76,7 +75,7 @@ struct StatementVisitor
 		if (!consequent)
 		{
 			// TODO: think about throwing an exception instead
-			context.logger.log(output::Priority::Error, "could not translate formula consequent");
+			context.logger.log(output::Priority::Error) << "could not translate formula consequent";
 			return;
 		}
 

include/anthem/Utils.h

@@ -31,13 +31,14 @@ inline input::Location location_cast(const Clingo::Location &location)
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
+// TODO: refactor
 inline void throwErrorAtLocation(const Clingo::Location &clingoLocation, const char *errorMessage,
 	Context &context)
 {
 	const auto location = location_cast<input::Location>(clingoLocation);
 
 	// TODO: think about removing this to avoid double error messages
-	context.logger.log(output::Priority::Error, location, errorMessage);
+	context.logger.log(output::Priority::Error, location) << errorMessage;
 
 	throw std::runtime_error(errorMessage);
 }

include/anthem/output/FormatScope.h

@@ -0,0 +1,48 @@
+#ifndef __ANTHEM__OUTPUT__FORMAT_SCOPE_H
+#define __ANTHEM__OUTPUT__FORMAT_SCOPE_H
+
+#include <anthem/output/ColorStream.h>
+#include <anthem/output/Formatting.h>
+
+namespace anthem
+{
+namespace output
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// FormatScope
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class FormatScope
+{
+	public:
+		explicit FormatScope(ColorStream &colorStream)
+		:	m_colorStream{colorStream}
+		{
+		}
+
+		~FormatScope()
+		{
+			m_colorStream << output::ResetFormat() << std::endl;
+		}
+
+		template<class T>
+		inline FormatScope &operator<<(T &&value)
+		{
+			m_colorStream << std::forward<T>(value);
+
+			return *this;
+		}
+
+	private:
+		ColorStream &m_colorStream;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/anthem/output/Logger.h

@@ -5,6 +5,7 @@
 
 #include <anthem/input/Location.h>
 #include <anthem/output/ColorStream.h>
+#include <anthem/output/FormatScope.h>
 #include <anthem/output/Priority.h>
 
 namespace anthem
@@ -32,8 +33,8 @@ class Logger
 		void setLogPriority(Priority logPriority);
 		void setColorPolicy(ColorStream::ColorPolicy colorPolicy);
 
-		void log(Priority priority, const char *message);
-		void log(Priority priority, const input::Location &location, const char *message);
+		FormatScope log(Priority priority);
+		FormatScope log(Priority priority, const input::Location &location);
 
 	private:
 		ColorStream m_outputStream;

include/anthem/output/NullStream.h

@@ -0,0 +1,38 @@
+#ifndef __ANTHEM__OUTPUT__NULL_STREAM_H
+#define __ANTHEM__OUTPUT__NULL_STREAM_H
+
+#include <anthem/output/ColorStream.h>
+
+namespace anthem
+{
+namespace output
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// NullStream
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class NullBuffer : public std::streambuf
+{
+	public:
+		int overflow(int c)
+		{
+			return c;
+		}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+extern ColorStream nullStream;
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

src/anthem/Translation.cpp

@@ -35,8 +35,7 @@ void translate(const std::vector<std::string> &fileNames, Context &context)
 
 void translate(const char *fileName, std::istream &stream, Context &context)
 {
-	// TODO: refactor
-	context.logger.log(output::Priority::Info, (std::string("reading ") + fileName).c_str());
+	context.logger.log(output::Priority::Info) << "reading " << fileName;
 
 	auto fileContent = std::string(std::istreambuf_iterator<char>(stream), {});
 
@@ -51,7 +50,7 @@ void translate(const char *fileName, std::istream &stream, Context &context)
 	const auto logger =
 		[&context](const Clingo::WarningCode, const char *text)
 		{
-			context.logger.log(output::Priority::Error, text);
+			context.logger.log(output::Priority::Error) << text;
 		};
 
 	Clingo::parse_program(fileContent.c_str(), translateStatement, logger);

src/anthem/output/Logger.cpp

@@ -1,6 +1,7 @@
 #include <anthem/output/Logger.h>
 
 #include <anthem/output/Formatting.h>
+#include <anthem/output/NullStream.h>
 
 namespace anthem
 {
@@ -92,28 +93,29 @@ void Logger::setColorPolicy(ColorStream::ColorPolicy colorPolicy)
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Logger::log(Priority priority, const char *message)
+FormatScope Logger::log(Priority priority)
 {
 	const auto priorityID = static_cast<int>(priority);
 
 	if (priorityID < static_cast<int>(m_logPriority))
-		return;
+		return FormatScope(detail::nullStream);
 
 	m_errorStream
 		<< priorityFormat(priority) << priorityName(priority) << ":"
 		<< ResetFormat() << " "
-		<< MessageBodyFormat << message
-		<< ResetFormat() << std::endl;
+		<< MessageBodyFormat;
+
+	return FormatScope(m_errorStream);
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Logger::log(Priority priority, const input::Location &location, const char *message)
+FormatScope Logger::log(Priority priority, const input::Location &location)
 {
 	const auto priorityID = static_cast<int>(priority);
 
 	if (priorityID < static_cast<int>(m_logPriority))
-		return;
+		return FormatScope(detail::nullStream);
 
 	m_errorStream
 		<< LocationFormat
@@ -121,8 +123,9 @@ void Logger::log(Priority priority, const input::Location &location, const char
 		<< ResetFormat() << " "
 		<< priorityFormat(priority) << priorityName(priority) << ":"
 		<< ResetFormat() << " "
-		<< MessageBodyFormat << message
-		<< ResetFormat() << std::endl;
+		<< MessageBodyFormat;
+
+	return FormatScope(m_errorStream);
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////

src/anthem/output/NullStream.cpp

@@ -0,0 +1,24 @@
+#include <anthem/output/NullStream.h>
+
+namespace anthem
+{
+namespace output
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// NullStream
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+NullBuffer nullBuffer;
+std::ostream nullOStream(&nullBuffer);
+ColorStream nullStream(nullOStream);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}