Type hint from schema when encountering empty aggregate. Fixes #127

src/ifcparse/IfcParse.cpp

@@ -662,7 +662,10 @@ void ArgumentList::read(IfcSpfLexer* t, std::vector<unsigned int>& ids) {
 }
 
 IfcUtil::ArgumentType ArgumentList::type() const {
-	if (list.empty()) return IfcUtil::Argument_UNKNOWN;
+	if (list.empty()) {
+		return IfcUtil::Argument_EMPTY_AGGREGATE;
+	}
+
 	const IfcUtil::ArgumentType elem_type = list[0]->type();
 	if (elem_type == IfcUtil::Argument_INT) {
 		return IfcUtil::Argument_AGGREGATE_OF_INT;
@@ -680,6 +683,8 @@ IfcUtil::ArgumentType ArgumentList::type() const {
 		return IfcUtil::Argument_AGGREGATE_OF_AGGREGATE_OF_DOUBLE;
 	} else if (elem_type == IfcUtil::Argument_AGGREGATE_OF_ENTITY_INSTANCE) {
 		return IfcUtil::Argument_AGGREGATE_OF_AGGREGATE_OF_ENTITY_INSTANCE;
+	} else if (elem_type == IfcUtil::Argument_EMPTY_AGGREGATE) {
+		return IfcUtil::Argument_AGGREGATE_OF_EMPTY_AGGREGATE;
 	} else {
 		return IfcUtil::Argument_UNKNOWN;
 	}

src/ifcparse/IfcUtil.cpp

@@ -105,12 +105,14 @@ static const char* const argument_type_string[] = {
 	"ENUMERATION",
 	"ENTITY INSTANCE",
 
+	"EMPTY AGGREGATE",
 	"AGGREGATE OF INT",
 	"AGGREGATE OF DOUBLE",
 	"AGGREGATE OF STRING",
 	"AGGREGATE OF BINARY",
 	"AGGREGATE OF ENTITY INSTANCE",
 
+	"AGGREGATE OF EMPTY AGGREGATE",
 	"AGGREGATE OF AGGREGATE OF INT",
 	"AGGREGATE OF AGGREGATE OF DOUBLE",
 	"AGGREGATE OF AGGREGATE OF ENTITY INSTANCE", 

src/ifcparse/IfcUtil.h

@@ -61,12 +61,14 @@ namespace IfcUtil {
 		Argument_ENUMERATION, 
 		Argument_ENTITY_INSTANCE,
 
+		Argument_EMPTY_AGGREGATE,
 		Argument_AGGREGATE_OF_INT,
 		Argument_AGGREGATE_OF_DOUBLE, 
 		Argument_AGGREGATE_OF_STRING,
 		Argument_AGGREGATE_OF_BINARY, 
 		Argument_AGGREGATE_OF_ENTITY_INSTANCE,
 	
+		Argument_AGGREGATE_OF_EMPTY_AGGREGATE,
 		Argument_AGGREGATE_OF_AGGREGATE_OF_INT,
 		Argument_AGGREGATE_OF_AGGREGATE_OF_DOUBLE,
 		Argument_AGGREGATE_OF_AGGREGATE_OF_ENTITY_INSTANCE, 
@@ -74,6 +76,7 @@ namespace IfcUtil {
 		Argument_UNKNOWN
 	};
 
+
     IFC_PARSE_API const char* ArgumentTypeToString(ArgumentType argument_type);
 
 	class IFC_PARSE_API IfcBaseClass {

src/ifcparse/IfcWritableEntity.h

@@ -65,7 +65,7 @@ namespace IfcWrite {
 		unsigned int id();
 		IfcWritableEntity* isWritable();
 
-		void setArgument(int i, Argument* a);
+		void setArgument(int i, Argument* a, IfcUtil::ArgumentType attr_type = IfcUtil::Argument_UNKNOWN);
 
 		void setArgument(int i);
 		void setArgumentDerived(int i);

src/ifcparse/IfcWrite.cpp

@@ -144,8 +144,10 @@ void IfcWritableEntity::setArgument(int i) {
 	_setArgument(i, boost::none);
 }
 
-void IfcWritableEntity::setArgument(int i, Argument* a) {
+void IfcWritableEntity::setArgument(int i, Argument* a, IfcUtil::ArgumentType attr_type) {
-	IfcUtil::ArgumentType attr_type = a->type();
+	if (attr_type == IfcUtil::Argument_UNKNOWN) {
+		attr_type = a->type();
+	}
 	switch(attr_type) {
 	case IfcUtil::Argument_NULL:
 		this->setArgument(i);
@@ -224,14 +226,18 @@ void IfcWritableEntity::setArgument(int i, Argument* a) {
 		}		
 		this->setArgument(i, mapped_instances); }
 		break;
+	case IfcUtil::Argument_EMPTY_AGGREGATE: 
+	case IfcUtil::Argument_AGGREGATE_OF_EMPTY_AGGREGATE: {
+		IfcUtil::ArgumentType t2 = IfcSchema::Type::GetAttributeType(type(), (unsigned) i);
+		this->setArgument(i, a, t2); }
+		break;
 	default:
 	case IfcUtil::Argument_UNKNOWN:
-		throw IfcParse::IfcException("Unknown argument encountered");
+		throw IfcParse::IfcException(std::string("Unknown attribute encountered: '") + a->toString() + "' at index '" + boost::lexical_cast<std::string>(i) + "'");
 		break;
 	}
 }
 
-
 void IfcWritableEntity::setArgumentDerived(int i) {
 	_setArgument(i, IfcWriteArgument::Derived());
 }