Fix hover documentation for xsi:type-derived child elements across namespaces

org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/catalog/XMLCatalogURIResolverExtension.java

@@ -83,6 +83,9 @@ public XMLInputSource resolveEntity(XMLResourceIdentifier resourceIdentifier) th
 	}
 
 	private boolean hasDTDorXMLSchema(String uri) {
+		if (extensionsRegistry.getDocumentProvider() == null) {
+			return false;
+		}
 		DOMDocument document = extensionsRegistry.getDocumentProvider().getDocument(uri);
 		if (document == null) {
 			return false;

org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/participants/ContentModelHoverParticipant.java

@@ -16,7 +16,9 @@
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Set;
 
 import org.eclipse.lemminx.dom.DOMAttr;
 import org.eclipse.lemminx.dom.DOMElement;
@@ -49,7 +51,7 @@ public Hover onTag(IHoverRequest hoverRequest, CancelChecker cancelChecker) thro
 		try {
 			ContentModelManager contentModelManager = hoverRequest.getComponent(ContentModelManager.class);
 			DOMElement element = (DOMElement) hoverRequest.getNode();
-			Collection<CMDocument> cmDocuments = contentModelManager.findCMDocument(element);
+			Collection<CMDocument> cmDocuments = collectCMDocuments(element, contentModelManager);
 			if (cmDocuments.isEmpty()) {
 				// no bound grammar -> no documentation
 				return null;
@@ -75,7 +77,7 @@ public Hover onAttributeName(IHoverRequest hoverRequest, CancelChecker cancelChe
 		DOMElement element = attribute.getOwnerElement();
 		try {
 			ContentModelManager contentModelManager = hoverRequest.getComponent(ContentModelManager.class);
-			Collection<CMDocument> cmDocuments = contentModelManager.findCMDocument(element);
+			Collection<CMDocument> cmDocuments = collectCMDocuments(element, contentModelManager);
 			if (cmDocuments.isEmpty()) {
 				// no bound grammar -> no documentation
 				return null;
@@ -113,7 +115,7 @@ public Hover onAttributeValue(IHoverRequest hoverRequest, CancelChecker cancelCh
 		DOMElement element = attribute.getOwnerElement();
 		try {
 			ContentModelManager contentModelManager = hoverRequest.getComponent(ContentModelManager.class);
-			Collection<CMDocument> cmDocuments = contentModelManager.findCMDocument(element);
+			Collection<CMDocument> cmDocuments = collectCMDocuments(element, contentModelManager);
 			if (cmDocuments.isEmpty()) {
 				// no bound grammar -> no documentation
 				return null;
@@ -147,7 +149,7 @@ public Hover onText(IHoverRequest hoverRequest, CancelChecker cancelChecker) thr
 		}
 		try {
 			ContentModelManager contentModelManager = hoverRequest.getComponent(ContentModelManager.class);
-			Collection<CMDocument> cmDocuments = contentModelManager.findCMDocument(element);
+			Collection<CMDocument> cmDocuments = collectCMDocuments(element, contentModelManager);
 			if (cmDocuments.isEmpty()) {
 				// no bound grammar -> no documentation
 				return null;
@@ -185,4 +187,43 @@ private static void fillHoverContent(MarkupContent content, List<MarkupContent>
 		}
 	}
 
+	/**
+	 * Collect the content model documents which may declare the given element. When
+	 * the element is inside an ancestor with an xsi:type attribute, the documents
+	 * bound to the ancestor's namespace are also collected so that derived types
+	 * declared in other schemas can be resolved.
+	 *
+	 * @param element             the hovered XML element.
+	 * @param contentModelManager the content model manager.
+	 * @return the content model documents to search.
+	 */
+	private static Collection<CMDocument> collectCMDocuments(DOMElement element,
+			ContentModelManager contentModelManager) {
+		Set<CMDocument> documents = new LinkedHashSet<>(contentModelManager.findCMDocument(element));
+		DOMElement current = element;
+		while (current != null) {
+			DOMElement parent = current.getParentNode() instanceof DOMElement ? (DOMElement) current.getParentNode()
+					: null;
+			if (parent != null && hasXSIType(parent)) {
+				documents.addAll(contentModelManager.findCMDocument(parent));
+			}
+			current = parent;
+		}
+		return documents;
+	}
+
+	private static boolean hasXSIType(DOMElement element) {
+		org.w3c.dom.NamedNodeMap attrs = element.getAttributes();
+		if (attrs == null) {
+			return false;
+		}
+		for (int i = 0; i < attrs.getLength(); i++) {
+			org.w3c.dom.Node attr = attrs.item(i);
+			if ("type".equals(attr.getLocalName()) && XSISchemaModel.XSI_WEBSITE.equals(attr.getNamespaceURI())) {
+				return true;
+			}
+		}
+		return false;
+	}
+
 }

org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/xsd/XSDPlugin.java

@@ -14,7 +14,6 @@
 
 import org.eclipse.lemminx.dom.DOMDocument;
 import org.eclipse.lemminx.extensions.contentmodel.model.ContentModelManager;
-import org.eclipse.lemminx.extensions.contentmodel.model.ContentModelProvider;
 import org.eclipse.lemminx.extensions.xsd.contentmodel.CMXSDContentModelProvider;
 import org.eclipse.lemminx.extensions.xsd.participants.XSDCodeLensParticipant;
 import org.eclipse.lemminx.extensions.xsd.participants.XSDCompletionParticipant;
@@ -87,8 +86,9 @@ public void start(InitializeParams params, XMLExtensionsRegistry registry) {
 		uiResolver = new XSDURIResolverExtension(registry.getDocumentProvider());
 		registry.getResolverExtensionManager().registerResolver(uiResolver);
 		// register XSD content model provider
-		ContentModelProvider modelProvider = new CMXSDContentModelProvider(registry.getResolverExtensionManager());
+		CMXSDContentModelProvider modelProvider = new CMXSDContentModelProvider(registry.getResolverExtensionManager());
 		contentModelManager = registry.getComponent(ContentModelManager.class);
+		modelProvider.setContentModelManager(contentModelManager);
 		contentModelManager.registerModelProvider(modelProvider);
 		// register completion, diagnostic participant
 		registry.registerCompletionParticipant(completionParticipant);

org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/xsd/contentmodel/CMXSDContentModelProvider.java

@@ -26,6 +26,7 @@
 import org.eclipse.lemminx.dom.SchemaLocation;
 import org.eclipse.lemminx.dom.SchemaLocationHint;
 import org.eclipse.lemminx.extensions.contentmodel.model.CMDocument;
+import org.eclipse.lemminx.extensions.contentmodel.model.ContentModelManager;
 import org.eclipse.lemminx.extensions.contentmodel.model.ContentModelProvider;
 import org.eclipse.lemminx.extensions.xerces.AbstractLSPErrorReporter;
 import org.eclipse.lemminx.extensions.xerces.LSPXMLEntityManager;
@@ -48,11 +49,22 @@ public class CMXSDContentModelProvider implements ContentModelProvider {
 
 	private static final String XSI_NO_NAMESPACE_SCHEMA_LOCATION_BINDING_KIND = "xsi:noNamespaceSchemaLocation";
 	private final URIResolverExtensionManager resolverExtensionManager;
+	private ContentModelManager contentModelManager;
 
 	public CMXSDContentModelProvider(URIResolverExtensionManager resolverExtensionManager) {
 		this.resolverExtensionManager = resolverExtensionManager;
 	}
 
+	/**
+	 * Sets the content model manager used to resolve cross-schema type
+	 * definitions (ex: xsi:type from a different namespace).
+	 *
+	 * @param contentModelManager the content model manager.
+	 */
+	public void setContentModelManager(ContentModelManager contentModelManager) {
+		this.contentModelManager = contentModelManager;
+	}
+
 	@Override
 	public boolean adaptFor(DOMDocument document, boolean internal) {
 		if (internal) {
@@ -110,7 +122,7 @@ public CMDocument createCMDocument(String key, boolean resolveExternalEntities)
 		XSModel model = loader.loadURI(key);
 		if (model != null) {
 			// XML Schema can be loaded
-			return new CMXSDDocument(model, loader);
+			return new CMXSDDocument(model, loader, contentModelManager);
 		}
 		return null;
 	}

org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/xsd/contentmodel/CMXSDDocument.java

@@ -58,6 +58,7 @@
 import org.eclipse.lemminx.dom.DOMNode;
 import org.eclipse.lemminx.extensions.contentmodel.model.CMDocument;
 import org.eclipse.lemminx.extensions.contentmodel.model.CMElementDeclaration;
+import org.eclipse.lemminx.extensions.contentmodel.model.ContentModelManager;
 import org.eclipse.lemminx.extensions.contentmodel.model.FilesChangedTracker;
 import org.eclipse.lemminx.extensions.xerces.ReflectionUtils;
 import org.eclipse.lemminx.extensions.xsd.utils.XSDUtils;
@@ -89,10 +90,16 @@ public class CMXSDDocument implements CMDocument, XSElementDeclHelper {
 	private final FilesChangedTracker tracker;
 
 	private final XSLoaderImpl xsLoader;
+	private final ContentModelManager contentModelManager;
 
 	public CMXSDDocument(XSModel model, XSLoaderImpl xsLoaderImpl) {
+		this(model, xsLoaderImpl, null);
+	}
+
+	public CMXSDDocument(XSModel model, XSLoaderImpl xsLoaderImpl, ContentModelManager contentModelManager) {
 		this.model = model;
 		this.xsLoader = xsLoaderImpl;
+		this.contentModelManager = contentModelManager;
 		this.elementMappings = new HashMap<>();
 		this.refinedElementMappings = new HashMap<>();
 		this.tracker = createFilesChangedTracker(model);
@@ -174,18 +181,14 @@ XSObjectList getSubstitutionGroup(XSElementDeclaration elementDeclaration) {
 
 	@Override
 	public CMElementDeclaration findCMElement(DOMElement element, String namespace) {
-		List<DOMElement> paths = new ArrayList<>();
-		while (element != null && (namespace == null || namespace.equals(element.getNamespaceURI()))) {
-			paths.add(0, element);
-			element = element.getParentNode() instanceof DOMElement ? (DOMElement) element.getParentNode() : null;
-		}
+		List<DOMElement> paths = collectPath(element, namespace);
 		CMXSDElementDeclaration declaration = null;
 		for (int i = 0; i < paths.size(); i++) {
 			DOMElement elt = paths.get(i);
 			if (i == 0) {
-				declaration = (CMXSDElementDeclaration) findElementDeclaration(elt.getLocalName(), namespace);
+				declaration = (CMXSDElementDeclaration) findElementDeclaration(elt.getLocalName());
 			} else {
-				declaration = (CMXSDElementDeclaration) declaration.findCMElement(elt.getLocalName(), namespace);
+				declaration = (CMXSDElementDeclaration) declaration.findCMElement(elt.getLocalName(), elt.getNamespaceURI());
 			}
 			if (declaration == null) {
 				break;
@@ -208,32 +211,92 @@ public CMElementDeclaration findCMElement(DOMElement element, String namespace)
 		return declaration;
 	}
 
-	private XSTypeDefinition findXsiType(DOMElement element) {
+	private static List<DOMElement> collectPath(DOMElement element, String namespace) {
+		List<DOMElement> paths = new ArrayList<>();
+		DOMElement current = element;
+		while (current != null && (namespace == null || namespace.equals(current.getNamespaceURI()))) {
+			paths.add(0, current);
+			current = current.getParentNode() instanceof DOMElement ? (DOMElement) current.getParentNode() : null;
+		}
+		if (hasXSITypeAncestor(current)) {
+			while (current != null) {
+				paths.add(0, current);
+				current = current.getParentNode() instanceof DOMElement ? (DOMElement) current.getParentNode() : null;
+			}
+		}
+		return paths;
+	}
+
+	private static boolean hasXSITypeAncestor(DOMElement element) {
+		DOMElement current = element;
+		while (current != null) {
+			if (hasXSITypeValue(current)) {
+				return true;
+			}
+			current = current.getParentNode() instanceof DOMElement ? (DOMElement) current.getParentNode() : null;
+		}
+		return false;
+	}
+
+	private static boolean hasXSITypeValue(DOMElement element) {
+		return getXSITypeValue(element) != null;
+	}
+
+	private static String getXSITypeValue(DOMElement element) {
 		org.w3c.dom.NamedNodeMap attrs = element.getAttributes();
 		if (attrs == null) {
 			return null;
 		}
 		for (int i = 0; i < attrs.getLength(); i++) {
 			Node attr = attrs.item(i);
 			if (attr.getLocalName().equals("type") && XSISchemaModel.XSI_WEBSITE.equals(attr.getNamespaceURI())) {
-				String[] possiblyQualifiedType = attr.getNodeValue().split(":", 2);
-				javax.xml.namespace.QName qualifiedType;
-				if (possiblyQualifiedType.length == 1) {
-					qualifiedType = new javax.xml.namespace.QName(
-							null,
-							possiblyQualifiedType[0]);
-				} else {
-					qualifiedType = new javax.xml.namespace.QName(
-							element.getNamespaceURI(possiblyQualifiedType[0]),
-							possiblyQualifiedType[1]);
+				return attr.getNodeValue();
+			}
+		}
+		return null;
+	}
+
+	private XSTypeDefinition findXsiType(DOMElement element) {
+		String typeValue = getXSITypeValue(element);
+		if (typeValue == null) {
+			return null;
+		}
+		String[] possiblyQualifiedType = typeValue.split(":", 2);
+		javax.xml.namespace.QName qualifiedType;
+		if (possiblyQualifiedType.length == 1) {
+			qualifiedType = new javax.xml.namespace.QName(null, possiblyQualifiedType[0]);
+		} else {
+			qualifiedType = new javax.xml.namespace.QName(
+					element.getNamespaceURI(possiblyQualifiedType[0]),
+					possiblyQualifiedType[1]);
+		}
+		// Try to find the type in the current schema model.
+		XSTypeDefinition exactType = (XSTypeDefinition) model.getComponents(XSConstants.TYPE_DEFINITION)
+				.get(qualifiedType);
+		if (exactType != null) {
+			return exactType;
+		}
+		// Try to find the type in the models bound to the XML document for the type namespace.
+		if (contentModelManager != null && qualifiedType.getNamespaceURI() != null) {
+			DOMDocument xmlDocument = element.getOwnerDocument();
+			if (xmlDocument != null) {
+				Collection<CMDocument> documents = contentModelManager.findCMDocument(xmlDocument,
+						qualifiedType.getNamespaceURI());
+				for (CMDocument document : documents) {
+					if (document instanceof CMXSDDocument) {
+						exactType = (XSTypeDefinition) ((CMXSDDocument) document).model
+								.getComponents(XSConstants.TYPE_DEFINITION).get(qualifiedType);
+						if (exactType != null) {
+							return exactType;
+						}
+					}
 				}
-				return (XSTypeDefinition) model.getComponents(XSConstants.TYPE_DEFINITION).get(qualifiedType);
 			}
 		}
 		return null;
 	}
 
-	private CMElementDeclaration findElementDeclaration(String tag, String namespace) {
+	private CMElementDeclaration findElementDeclaration(String tag) {
 		for (CMElementDeclaration cmElement : getElements()) {
 			if (cmElement.getLocalName().equals(tag)) {
 				return cmElement;

org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/extensions/contentmodel/XMLSchemaHoverExtensionsTest.java

@@ -425,12 +425,67 @@ public boolean isOpen() {
 		}));
 	}
 
+	/**
+	 * See https://github.com/eclipse-lemminx/lemminx/issues/1787
+	 *
+	 * Hover documentation for child elements of xsi:type-derived complex types
+	 * across namespaces.
+	 *
+	 * @throws BadLocationException
+	 * @throws MalformedURIException
+	 */
+	@Test
+	public void testHoverXSITypeDerivedChildAcrossNamespaces() throws BadLocationException, MalformedURIException {
+		String aSchemaURI = getXMLSchemaFileURI("xsi-type-derived/a.xsd");
+		String bSchemaURI = getXMLSchemaFileURI("xsi-type-derived/b.xsd");
+
+		// Hover on <a:Title> should show documentation from a.xsd
+		String xmlA = "<?xml version=\"1.0\" encoding=\"UTF-8\"?\u003e\n" + //
+				"\u003cm:Root xmlns:m=\"http://main\"\n" + //
+				"        xmlns:a=\"http://a\"\n" + //
+				"        xmlns:b=\"http://b\"\n" + //
+				"        xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n" + //
+				"        xsi:schemaLocation=\"http://main main.xsd http://a a.xsd http://b b.xsd\"\u003e\n" + //
+				"  \u003cm:Data xsi:type=\"a:ADerived\"\u003e\n" + //
+				"    \u003ca:Tit|le/\u003e\n" + //
+				"  \u003c/m:Data\u003e\n" + //
+				"\u003c/m:Root>";
+		assertHover(xmlA, "src/test/resources/xsd/xsi-type-derived/test.xml",
+				"Documentation for Title from namespace a" + //
+						System.lineSeparator() + //
+						System.lineSeparator() + "Source: [a.xsd](" + aSchemaURI + ")",
+				r(7, 5, 7, 12));
+
+		// Hover on <b:Title> should show documentation from b.xsd
+		String xmlB = "<?xml version=\"1.0\" encoding=\"UTF-8\"?\u003e\n" + //
+				"\u003cm:Root xmlns:m=\"http://main\"\n" + //
+				"        xmlns:a=\"http://a\"\n" + //
+				"        xmlns:b=\"http://b\"\n" + //
+				"        xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n" + //
+				"        xsi:schemaLocation=\"http://main main.xsd http://a a.xsd http://b b.xsd\"\u003e\n" + //
+				"  \u003cm:Data xsi:type=\"b:BDerived\"\u003e\n" + //
+				"    \u003cb:Tit|le/\u003e\n" + //
+				"  \u003c/m:Data\u003e\n" + //
+				"\u003c/m:Root>";
+		assertHover(xmlB, "src/test/resources/xsd/xsi-type-derived/test.xml",
+				"Documentation for Title from namespace b" + //
+						System.lineSeparator() + //
+						System.lineSeparator() + "Source: [b.xsd](" + bSchemaURI + ")",
+				r(7, 5, 7, 12));
+	}
+
 	private static void assertHover(String value, String expectedHoverLabel, Range expectedHoverRange)
 			throws BadLocationException {
 		XMLAssert.assertHover(new XMLLanguageService(), value, "src/test/resources/catalogs/catalog.xml", null,
 				expectedHoverLabel, expectedHoverRange);
 	}
 
+	private static void assertHover(String value, String fileURI, String expectedHoverLabel, Range expectedHoverRange)
+			throws BadLocationException {
+		XMLAssert.assertHover(new XMLLanguageService(), value, null, fileURI,
+				expectedHoverLabel, expectedHoverRange);
+	}
+
 	private static String getXMLSchemaFileURI(String schemaURI) throws MalformedURIException {
 		return XMLEntityManager.expandSystemId("xsd/" + schemaURI, "src/test/resources/test.xml", true).replace("///",
 				"/");