Initial implementation of a semantic tokens reconciler

Initial implementation of a semantic tokens reconciler which supports
only SemanticTokensFull.

The reconciler uses the theme defined for TM4E so that the same styles
are used for the same token types.

In addition to the tokens defined for TM4E, also the deprecated modifier
is supported by marking striking out the regions.

org.eclipse.lsp4e/META-INF/MANIFEST.MF

@@ -25,6 +25,7 @@ Require-Bundle: org.eclipse.core.runtime;bundle-version="3.12.0",
  org.eclipse.debug.ui;bundle-version="3.11.200",
  org.eclipse.swt,
  org.eclipse.jdt.annotation;bundle-version="2.1.0";resolution:=optional,
+ org.eclipse.tm4e.ui,
  org.eclipse.ui.editors,
  org.eclipse.ui.navigator;bundle-version="3.6.100",
  org.eclipse.lsp4j;bundle-version="[0.18.0,0.19.0)",

org.eclipse.lsp4e/plugin.xml

@@ -657,4 +657,21 @@
          </enabledWhen>
       </reconciler>
    </extension>   
+   <extension
+         point="org.eclipse.ui.genericeditor.reconcilers">
+      <reconciler
+            class="org.eclipse.lsp4e.operations.semanticTokens.SemanticHighlightReconciler"
+            contentType="org.eclipse.core.runtime.text">
+         <enabledWhen>
+           <or>
+             <with variable="editorInput">
+               <test property="org.eclipse.lsp4e.hasLanguageServer"/>
+             </with>
+             <with variable="viewer">
+               <test property="org.eclipse.lsp4e.hasLanguageServer"/>
+             </with>
+           </or>
+         </enabledWhen>
+      </reconciler>
+   </extension> 
 </plugin>

org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/semanticTokens/SemanticHighlightReconciler.java

@@ -0,0 +1,36 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Avaloq Evolution AG.
+ * This program and the accompanying materials are made
+ * available under the terms of the Eclipse Public License 2.0
+ * which is available at https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package org.eclipse.lsp4e.operations.semanticTokens;
+
+import org.eclipse.jface.text.IDocument;
+import org.eclipse.jface.text.ITextViewer;
+import org.eclipse.jface.text.reconciler.MonoReconciler;
+
+
+public class SemanticHighlightReconciler extends MonoReconciler {
+
+  public SemanticHighlightReconciler() {
+    super(new SemanticHighlightReconcilerStrategy(), false);
+  }
+
+  @Override
+  public void install(final ITextViewer textViewer) {
+    super.install(textViewer);
+    // no need to do that if https://bugs.eclipse.org/bugs/show_bug.cgi?id=521326 is accepted
+    ((SemanticHighlightReconcilerStrategy) getReconcilingStrategy(IDocument.DEFAULT_CONTENT_TYPE)).install(textViewer);
+  }
+
+  @Override
+  public void uninstall() {
+    super.uninstall();
+    // no need to do that if https://bugs.eclipse.org/bugs/show_bug.cgi?id=521326 is accepted
+    ((SemanticHighlightReconcilerStrategy) getReconcilingStrategy(IDocument.DEFAULT_CONTENT_TYPE)).uninstall();
+  }
+
+}