Improved TransformationFacade error handling

* ErrorHandler class created in 5859cb6 now caches all errors instead of pushing them to std::cerr
** cached errors are retrieved by TransformationFacade's "generate" member method
* test frontend pushes all errors to std::cerr
* FunctionTransform returns errors to the calling template as XML
** FunctionTransform test case demonstrates how one may test for successful transformation
* "generate" member method returns std::string vector wrapped in a std::unique_ptr
** this is used as a kind of optional pointer, as the std::unique_ptr instance only wraps a vector if errors where actually generated

1 files changed, 40 insertions, 23 deletions

diff --git a/src/support/error_handler.cc b/src/support/error_handler.cc
index 9a898a6..db54225 100644
--- a/src/support/error_handler.cc
+++ b/src/support/error_handler.cc
@@ -6,38 +6,55 @@
 
 #include "support/xerces_string_guard.h"
 
+namespace {
+
+inline std::string getMessage(const xercesc::SAXParseException& exception) {
+	return std::string(
+		*InputXSLT::XercesStringGuard<char>(exception.getMessage())
+	);
+}
+
+}
+
 namespace InputXSLT {
 
-ErrorHandler::ErrorHandler(const std::string& transformation):
-	transformation_path_(transformation) { }
+ErrorHandler::ErrorHandler():
+	error_cache_{} { }
+
+void ErrorHandler::warning(const xercesc::SAXParseException& exception) {
+	this->constructErrorCache();
 
-void ErrorHandler::warning(const xercesc::SAXParseException& e) {
-	std::cerr << "Warning in "
-	          << "'"
-	          << this->transformation_path_
-	          << "': "
-	          << *XercesStringGuard<char>(e.getMessage())
-	          << std::endl;
+	this->error_cache_->emplace_back(
+		"Warning: " + getMessage(exception)
+	);
 }
 
-void ErrorHandler::error(const xercesc::SAXParseException& e) {
-	std::cerr << "Error in "
-	          << "'"
-	          << this->transformation_path_
-	          << "': "
-	          << *XercesStringGuard<char>(e.getMessage())
-	          << std::endl;
+void ErrorHandler::error(const xercesc::SAXParseException& exception) {
+	this->constructErrorCache();
+
+	this->error_cache_->emplace_back(
+		"Error: " + getMessage(exception)
+	);
 }
 
-void ErrorHandler::fatalError(const xercesc::SAXParseException& e) {
-	std::cerr << "Fatal error in "
-	          << "'"
-	          << this->transformation_path_
-	          << "': "
-	          << *XercesStringGuard<char>(e.getMessage())
-	          << std::endl;
+void ErrorHandler::fatalError(const xercesc::SAXParseException& exception) {
+	this->constructErrorCache();
+
+	this->error_cache_->emplace_back(
+		"Fatal error: " + getMessage(exception)
+	);
 }
 
 void ErrorHandler::resetErrors() { }
 
+auto ErrorHandler::getCachedErrors() -> error_cache_ptr {
+	return error_cache_ptr(this->error_cache_.release());
+}
+
+void ErrorHandler::constructErrorCache() {
+	if ( !this->error_cache_ ) {
+		this->error_cache_.reset(new error_cache());
+	}
+}
+
 }