Implemented WarningCapacitor as a counterpart to ErrorCapacitor

* in difference to ErrorCapacitor this class doesn't throw an exception on "discharge" but returns the gathered warnings
* adapted FunctionTransform and frontend error handling to include warnings
* added static "try_create" method to TransformationFacade
** wraps construction error handling
** custom logic may be embedded using the std::function argument
*** this was implemented to prevent unneccessary code duplication for handling both construction and generation errors
* adapted FunctionTransform to return warning as "warning" nodes in the result tree
** added functional lambda expression factory method "handleErrors"
*** returns a error handling lambda expression for a given ResultNodeFacade
* implemented WarningGuard class in frontend executable
** guarantees warnings to be printed to std::cerr independent of any exceptions

1 files changed, 26 insertions, 0 deletions

diff --git a/src/support/error/warning_capacitor.cc b/src/support/error/warning_capacitor.cc
new file mode 100644
index 0000000..f8d2b99
--- /dev/null
+++ b/src/support/error/warning_capacitor.cc
@@ -0,0 +1,26 @@
+#include "warning_capacitor.h"
+
+namespace InputXSLT {
+
+WarningCapacitor::WarningCapacitor(ErrorMultiplexer* multiplexer):
+	ErrorMultiplexer::receiver(multiplexer),
+	warning_cache_(new warning_cache()) { }
+
+auto WarningCapacitor::discharge() -> warning_cache_ptr {
+	warning_cache_ptr tmp(std::move(this->warning_cache_));
+
+	this->warning_cache_.reset(new warning_cache());
+
+	return std::move(tmp);
+}
+
+void WarningCapacitor::receive(
+	const ErrorMultiplexer::error_type type,
+	const std::string& message
+) {
+	if ( type == ErrorMultiplexer::error_type::warning ) {
+		this->warning_cache_->emplace_back(message);
+	}
+}
+
+}