Add support for textDocument/references for DTD

Fixes #234

Signed-off-by: azerr <[email protected]>

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/extensions/dtd/DTDPlugin.java

@@ -16,9 +16,11 @@
 import org.eclipse.lsp4xml.extensions.dtd.contentmodel.CMDTDContentModelProvider;
 import org.eclipse.lsp4xml.extensions.dtd.participants.DTDDefinitionParticipant;
 import org.eclipse.lsp4xml.extensions.dtd.participants.DTDHighlightingParticipant;
+import org.eclipse.lsp4xml.extensions.dtd.participants.DTDReferenceParticipant;
 import org.eclipse.lsp4xml.extensions.dtd.participants.diagnostics.DTDDiagnosticsParticipant;
 import org.eclipse.lsp4xml.services.extensions.IDefinitionParticipant;
 import org.eclipse.lsp4xml.services.extensions.IHighlightingParticipant;
+import org.eclipse.lsp4xml.services.extensions.IReferenceParticipant;
 import org.eclipse.lsp4xml.services.extensions.IXMLExtension;
 import org.eclipse.lsp4xml.services.extensions.XMLExtensionsRegistry;
 import org.eclipse.lsp4xml.services.extensions.diagnostics.IDiagnosticsParticipant;
@@ -32,11 +34,13 @@ public class DTDPlugin implements IXMLExtension {
 	private final IDiagnosticsParticipant diagnosticsParticipant;
 	private final IDefinitionParticipant definitionParticipant;
 	private IHighlightingParticipant highlightingParticipant;
+	private IReferenceParticipant referenceParticipant;
 
 	public DTDPlugin() {
 		diagnosticsParticipant = new DTDDiagnosticsParticipant();
 		definitionParticipant = new DTDDefinitionParticipant();
 		highlightingParticipant = new DTDHighlightingParticipant();
+		referenceParticipant = new DTDReferenceParticipant();
 	}
 
 	@Override
@@ -56,6 +60,8 @@ public void start(InitializeParams params, XMLExtensionsRegistry registry) {
 		registry.registerDefinitionParticipant(definitionParticipant);
 		// register highlighting participant
 		registry.registerHighlightingParticipant(highlightingParticipant);
+		// register reference participant
+		registry.registerReferenceParticipant(referenceParticipant);
 	}
 
 	@Override
@@ -66,5 +72,7 @@ public void stop(XMLExtensionsRegistry registry) {
 		registry.unregisterDefinitionParticipant(definitionParticipant);
 		// unregister highlighting participant
 		registry.unregisterHighlightingParticipant(highlightingParticipant);
+		// register reference participant
+		registry.unregisterReferenceParticipant(referenceParticipant);
 	}
 }

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/extensions/dtd/participants/DTDReferenceParticipant.java

@@ -0,0 +1,50 @@
+/*******************************************************************************
+* Copyright (c) 2019 Red Hat Inc. and others.
+* All rights reserved. This program and the accompanying materials
+* which accompanies this distribution, and is available at
+* http://www.eclipse.org/legal/epl-v20.html
+*
+* Contributors:
+*     Red Hat Inc. - initial API and implementation
+*******************************************************************************/
+package org.eclipse.lsp4xml.extensions.dtd.participants;
+
+import java.util.List;
+
+import org.eclipse.lsp4j.Location;
+import org.eclipse.lsp4j.Position;
+import org.eclipse.lsp4j.ReferenceContext;
+import org.eclipse.lsp4j.jsonrpc.CancelChecker;
+import org.eclipse.lsp4xml.dom.DOMDocument;
+import org.eclipse.lsp4xml.dom.DOMNode;
+import org.eclipse.lsp4xml.dom.DTDElementDecl;
+import org.eclipse.lsp4xml.extensions.dtd.utils.DTDUtils;
+import org.eclipse.lsp4xml.services.extensions.AbstractReferenceParticipant;
+import org.eclipse.lsp4xml.utils.XMLPositionUtility;
+
+/**
+ * DTD reference
+ * 
+ * @author Angelo ZERR
+ *
+ */
+public class DTDReferenceParticipant extends AbstractReferenceParticipant {
+
+	@Override
+	protected boolean match(DOMDocument document) {
+		return true;
+	}
+
+	@Override
+	protected void findReferences(DOMNode node, Position position, int offset, ReferenceContext context,
+			List<Location> locations, CancelChecker cancelChecker) {
+		// DTD reference works only when references is done on an <!ELEMENT name
+		if (!node.isDTDElementDecl()) {
+			return;
+		}
+		DTDElementDecl elementDecl = (DTDElementDecl) node;
+		DTDUtils.searchDTDOriginElementDecls(elementDecl,
+				(origin, target) -> locations.add(XMLPositionUtility.createLocation(origin)), cancelChecker);
+	}
+
+}