Fix input/output count in Element::clearContent (AcademySoftwareFound…

…ation#1520)

When clearContent() is called on an InterfaceElement its _inputCount and _outputCount were not updated even though all inputs and outputs were removed. This led to problems including potential crash in Document::validate().

source/MaterialXCore/Element.h

@@ -739,7 +739,7 @@ class MX_CORE_API Element : public std::enable_shared_from_this<Element>
     void copyContentFrom(const ConstElementPtr& source);
 
     /// Clear all attributes and descendants from this element.
-    void clearContent();
+    virtual void clearContent();
 
     /// Using the input name as a starting point, modify it to create a valid,
     /// unique name for a child element.

source/MaterialXCore/Interface.cpp

@@ -611,6 +611,13 @@ ConstInterfaceElementPtr InterfaceElement::getDeclaration(const string&) const
     return InterfaceElementPtr();
 }
 
+void InterfaceElement::clearContent()
+{
+    _inputCount = 0;
+    _outputCount = 0;
+    TypedElement::clearContent();
+}
+
 bool InterfaceElement::hasExactInputMatch(ConstInterfaceElementPtr declaration, string* message) const
 {
     for (InputPtr input : getActiveInputs())

source/MaterialXCore/Interface.h

@@ -639,6 +639,9 @@ class MX_CORE_API InterfaceElement : public TypedElement
     ///    no declaration was found.
     virtual ConstInterfaceElementPtr getDeclaration(const string& target = EMPTY_STRING) const;
 
+    /// Clear all attributes and descendants from this element.
+    void clearContent() override;
+
     /// Return true if this instance has an exact input match with the given
     /// declaration, where each input of this the instance corresponds to a
     /// declaration input of the same name and type.

source/MaterialXTest/MaterialXCore/Node.cpp

@@ -136,6 +136,24 @@ TEST_CASE("Node", "[node]")
     REQUIRE(doc->getOutputs().empty());
 }
 
+TEST_CASE("Node inputCount repro", "[node]")
+{
+    // Create a document.
+    mx::DocumentPtr doc = mx::createDocument();
+    mx::NodePtr constant = doc->addNode("constant");
+    constant->setInputValue<float>("value", 0.5f);
+
+    // Check that input count is correct after clearContent
+    constant->clearContent();
+    CHECK(constant->getInputCount() == 0);
+
+    // Check that validate succeeds after clear and rebuild
+    constant->setType("float");
+    mx::OutputPtr output = doc->addOutput(mx::EMPTY_STRING, "float");
+    output->setConnectedNode(constant);
+    CHECK(doc->validate());
+}
+
 TEST_CASE("Flatten", "[nodegraph]")
 {
     // Read an example containing graph-based custom nodes.

source/PyMaterialX/PyMaterialXCore/PyInterface.cpp

@@ -93,6 +93,7 @@ void bindPyInterface(py::module& mod)
         .def("getDefaultVersion", &mx::InterfaceElement::getDefaultVersion)
         .def("getDeclaration", &mx::InterfaceElement::getDeclaration,
             py::arg("target") = mx::EMPTY_STRING)
+        .def("clearContent", &mx::InterfaceElement::clearContent)
         .def("hasExactInputMatch", &mx::InterfaceElement::hasExactInputMatch,
             py::arg("declaration"), py::arg("message") = nullptr)
         BIND_INTERFACE_TYPE_INSTANCE(integer, int)