3 files changed, 62 insertions, 0 deletions

diff --git a/src/core/model/Domain.cpp b/src/core/model/Domain.cpp
index 6f33ebd..3cc9755 100644
--- a/src/core/model/Domain.cpp
+++ b/src/core/model/Domain.cpp
@@ -471,6 +471,19 @@ NodeVector<FieldDescriptor> Descriptor::getDefaultFields() const
 	return res;
 }
 
+NodeVector<StructuredClass> Descriptor::getPermittedChildren() const
+{
+	// TODO: In principle a cast would be nicer here, but for now we copy.
+	NodeVector<Node> nodes = collect(this, [](Handle<Node> n) {
+		return n->isa(&RttiTypes::StructuredClass);
+	});
+	NodeVector<StructuredClass> res;
+	for (auto n : nodes) {
+		res.push_back(n.cast<StructuredClass>());
+	}
+	return res;
+}
+
 static ssize_t getFieldDescriptorIndex(const NodeVector<FieldDescriptor> &fds,
                                        const std::string &name)
 {
diff --git a/src/core/model/Domain.hpp b/src/core/model/Domain.hpp
index c277812..6bc2fba 100644
--- a/src/core/model/Domain.hpp
+++ b/src/core/model/Domain.hpp
@@ -624,6 +624,18 @@ public:
 	 *         children of an instance of this Descriptor.
 	 */
 	NodeVector<FieldDescriptor> getDefaultFields() const;
+
+	/**
+	 * Returns a vector of all StructuredClasses that are allowed as children
+	 * of an instance of this Descriptor in the structure tree. This also makes
+	 * use of transparency.
+	 * The list is sorted by the number of transparent elements that have to be
+	 * constructed to arrive at the respective FieldDescriptor.
+	 *
+	 * @return a vector of all StructuredClasses that are allowed as children
+	 *         of an instance of this Descriptor in the structure tree.
+	 */
+	NodeVector<StructuredClass> getPermittedChildren() const;
 };
 /*
  * TODO: We should discuss Cardinalities one more time. Is it smart to define
diff --git a/test/core/model/DomainTest.cpp b/test/core/model/DomainTest.cpp
index 83f290f..8fcbdf2 100644
--- a/test/core/model/DomainTest.cpp
+++ b/test/core/model/DomainTest.cpp
@@ -301,6 +301,43 @@ TEST(Descriptor, getDefaultFields)
 	ASSERT_EQ(F_field, fields[1]);
 }
 
+TEST(Descriptor, getPermittedChildren)
+{
+	// analyze the book domain.
+	TerminalLogger logger{std::cout};
+	Manager mgr{1};
+	Rooted<SystemTypesystem> sys{new SystemTypesystem(mgr)};
+	// Get the domain.
+	Rooted<Domain> domain = constructBookDomain(mgr, sys, logger);
+	// get the relevant classes.
+	Rooted<StructuredClass> book = getClass("book", domain);
+	Rooted<StructuredClass> section = getClass("section", domain);
+	Rooted<StructuredClass> paragraph = getClass("paragraph", domain);
+	Rooted<StructuredClass> text = getClass("text", domain);
+	/*
+	 * as permitted children we expect section, paragraph and text in exactly
+	 * that order. section should be before paragraph because of declaration
+	 * order and text should be last because it needs a transparent paragraph
+	 * in between.
+	 */
+	NodeVector<StructuredClass> children = book->getPermittedChildren();
+	ASSERT_EQ(3, children.size());
+	ASSERT_EQ(section, children[0]);
+	ASSERT_EQ(paragraph, children[1]);
+	ASSERT_EQ(text, children[2]);
+
+	// Now we add a subclass to text.
+	Rooted<StructuredClass> sub{new StructuredClass(
+	    mgr, "Subclass", domain, Cardinality::any(), text, true, false)};
+	// And that should be in the result list as well now.
+	children = book->getPermittedChildren();
+	ASSERT_EQ(4, children.size());
+	ASSERT_EQ(section, children[0]);
+	ASSERT_EQ(paragraph, children[1]);
+	ASSERT_EQ(text, children[2]);
+	ASSERT_EQ(sub, children[3]);
+}
+
 TEST(StructuredClass, isSubclassOf)
 {
 	// create an inheritance hierarchy.