Bug 536320 - Do not show LSP4E diagnostics in the C++ editor

Requires https://git.eclipse.org/r/c/lsp4e/lsp4e/+/168414
Allow LS to be started
	from "Generic Editor" only
		and
	if ".settings/org.eclipse.cdt.lsp.core.prefs" has "prefer=false"
actually this blocks LSP from launching until user will configure it
explicitly.
UI to configure for workspace and project.

Change-Id: I7104d21f90380a5de7ccae157ea4299e0558a27c
Signed-off-by: Alexander Fedorov <alexander.fedorov@arsysop.ru>

lsp/org.eclipse.cdt.lsp.core.tests/src/org/eclipse/cdt/lsp/internal/core/workspace/tests/ResolveDocumentUriTest.java

@@ -11,11 +11,11 @@
  * Contributors:
  *     Alexander Fedorov (ArSysOp) - initial API and implementation
  *******************************************************************************/
-package org.eclipse.cdt.lsp.text.tests;
+package org.eclipse.cdt.lsp.internal.core.workspace.tests;
 
 import static org.junit.Assert.assertFalse;
 
-import org.eclipse.cdt.lsp.internal.text.ResolveDocumentUri;
+import org.eclipse.cdt.lsp.internal.core.workspace.ResolveDocumentUri;
 import org.eclipse.core.filebuffers.FileBuffers;
 import org.eclipse.core.filebuffers.LocationKind;
 import org.eclipse.core.runtime.Path;

lsp/org.eclipse.cdt.lsp.core/META-INF/MANIFEST.MF

@@ -8,6 +8,7 @@ Bundle-Vendor: %Bundle-Vendor
 Bundle-RequiredExecutionEnvironment: JavaSE-11
 Require-Bundle: com.google.gson;bundle-version="2.8.2",
  org.eclipse.cdt.core,
+ org.eclipse.core.filebuffers;bundle-version="3.6.1000",
  org.eclipse.core.resources,
  org.eclipse.core.runtime,
  org.eclipse.lsp4e,
@@ -18,8 +19,10 @@ Require-Bundle: com.google.gson;bundle-version="2.8.2",
  org.eclipse.ui
 Export-Package: org.eclipse.cdt.lsp;x-friends:="org.eclipse.cdt.lsp.ui,org.eclipse.cdt.lsp.clangd",
  org.eclipse.cdt.lsp.core;x-friends:="org.eclipse.cdt.lsp.ui",
+ org.eclipse.cdt.lsp.core.preferences;x-friends:="org.eclipse.cdt.lsp.ui",
  org.eclipse.cdt.lsp.internal.core;x-internal:=true,
- org.eclipse.cdt.lsp.internal.text;x-friends:="org.eclipse.cdt.lsp.ui"
+ org.eclipse.cdt.lsp.internal.core.preferences;x-friends:="org.eclipse.cdt.lsp.ui",
+ org.eclipse.cdt.lsp.internal.core.workspace;x-friends:="org.eclipse.cdt.lsp.ui"
 Bundle-Activator: org.eclipse.cdt.lsp.core.Activator
 Bundle-ActivationPolicy: lazy
 Service-Component: OSGI-INF/org.eclipse.cdt.lsp.internal.core.ContributedLanguageServers.xml,

lsp/org.eclipse.cdt.lsp.core/plugin.xml

@@ -36,6 +36,12 @@
       <contentTypeMapping
             contentType="org.eclipse.cdt.lsp.core"
             id="org.eclipse.cdt.lsp.core">
+         <enabledWhen
+               description="Project-level settings">
+            <reference
+                  definitionId="org.eclipse.cdt.lsp.core.projectAllows">
+            </reference>
+         </enabledWhen>
       </contentTypeMapping>
    </extension>
    <extension
@@ -44,4 +50,22 @@
             class="org.eclipse.cdt.lsp.core.PreferenceInitializer">
       </initializer>
    </extension>
+   <extension
+         point="org.eclipse.core.expressions.definitions">
+      <definition
+            id="org.eclipse.cdt.lsp.core.projectAllows">
+         <and>
+            <reference
+                  definitionId="org.eclipse.ui.genericeditor.GenericEditor.active">
+            </reference>
+            <with
+                  variable="activeEditor">
+               <test
+                     property="org.eclipse.cdt.lsp.documents.prefer"
+                     value="true">
+               </test>
+            </with>
+         </and>
+      </definition>
+   </extension>
 </plugin>

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/core/preferences/LanguageServerPreferenceMetadata.java

@@ -0,0 +1,33 @@
+/*******************************************************************************
+ * Copyright (c) 2020 ArSysOp and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Alexander Fedorov (ArSysOp) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.lsp.core.preferences;
+
+import org.eclipse.core.runtime.preferences.PreferenceMetadata;
+
+/**
+ * The metadata for preferences to configure language server
+ *
+ */
+public interface LanguageServerPreferenceMetadata {
+
+	/**
+	 * Returns the metadata for the "Prefer Language Server" preference, must not return <code>null</code>.
+	 *
+	 * @return the metadata for the "Prefer Language Server" preference
+	 *
+	 * @see LanguageServerPreferences#preferLanguageServer()
+	 */
+	PreferenceMetadata<Boolean> preferLanguageServer();
+
+}

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/internal/core/LspCoreMessages.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2019 Eclipse Foundation and others.
+ * Copyright (c) 2019, 2020 Eclipse Contributors and others.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
@@ -8,7 +8,7 @@
  * SPDX-License-Identifier: EPL-2.0
  *
  * Contributors:
- *     Alexander Fedorov <alexander.fedorov@arsysop.ru> - initial API and implementatin
+ *     Alexander Fedorov <alexander.fedorov@arsysop.ru> - ongoing support
  *******************************************************************************/
 package org.eclipse.cdt.lsp.internal.core;
 
@@ -23,6 +23,8 @@ public class LspCoreMessages extends NLS {
 		NLS.initializeMessages(BUNDLE_NAME, LspCoreMessages.class);
 	}
 
+	public static String LanguageServerDefaults_prefer_description;
+	public static String LanguageServerDefaults_prefer_name;
 	public static String ShowStatus_busy;
 	public static String ShowStatus_idle;
 

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/internal/core/LspCoreMessages.properties

@@ -1,5 +1,5 @@
 ###############################################################################
-# Copyright (c) 2019 Eclipse Foundation and others
+# Copyright (c) 2019, 2020 Eclipse Contributors and others
 #
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
@@ -8,9 +8,10 @@
 # SPDX-License-Identifier: EPL-2.0
 #
 # Contributors:
-#     Eclipse Foundation - initial API and implementation
+#     Alexander Fedorov <alexander.fedorov@arsysop.ru> - ongoing support
-#     Alexander Fedorov <alexander.fedorov@arsysop.ru> - Bug 558484
 ###############################################################################
 
+LanguageServerDefaults_prefer_description=Prefer to use language server instead of "classic" facilities
+LanguageServerDefaults_prefer_name=Prefer Language Server
 ShowStatus_busy={0} : Busy | {1} Jobs
 ShowStatus_idle={0} : Idle

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/internal/core/preferences/LanguageServerDefaults.java

@@ -0,0 +1,29 @@
+/*******************************************************************************
+ * Copyright (c) 2020 ArSysOp and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Alexander Fedorov (ArSysOp) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.lsp.internal.core.preferences;
+
+import org.eclipse.cdt.lsp.core.preferences.LanguageServerPreferenceMetadata;
+import org.eclipse.cdt.lsp.internal.core.LspCoreMessages;
+import org.eclipse.core.runtime.preferences.PreferenceMetadata;
+
+public class LanguageServerDefaults implements LanguageServerPreferenceMetadata {
+
+	@Override
+	public PreferenceMetadata<Boolean> preferLanguageServer() {
+		return new PreferenceMetadata<>(Boolean.class, "prefer_language_server", false, //$NON-NLS-1$
+				LspCoreMessages.LanguageServerDefaults_prefer_name,
+				LspCoreMessages.LanguageServerDefaults_prefer_description);
+	}
+
+}

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/internal/core/workspace/PreferLanguageServer.java

@@ -0,0 +1,62 @@
+/*******************************************************************************
+ * Copyright (c) 2020 ArSysOp and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Alexander Fedorov (ArSysOp) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.lsp.internal.core.workspace;
+
+import java.util.Optional;
+import java.util.function.Predicate;
+
+import org.eclipse.cdt.lsp.core.Activator;
+import org.eclipse.cdt.lsp.core.preferences.LanguageServerPreferenceMetadata;
+import org.eclipse.cdt.lsp.internal.core.preferences.LanguageServerDefaults;
+import org.eclipse.core.resources.IFile;
+import org.eclipse.core.resources.IProject;
+import org.eclipse.core.resources.ProjectScope;
+import org.eclipse.core.runtime.Platform;
+import org.eclipse.core.runtime.preferences.IScopeContext;
+import org.eclipse.core.runtime.preferences.PreferenceMetadata;
+import org.eclipse.jface.text.IDocument;
+
+public final class PreferLanguageServer implements Predicate<IDocument> {
+
+	private final ResolveDocumentFile file;
+	private final LanguageServerPreferenceMetadata metadata;
+
+	public PreferLanguageServer() {
+		file = new ResolveDocumentFile();
+		metadata = new LanguageServerDefaults();
+	}
+
+	@Override
+	public boolean test(IDocument document) {
+		Optional<IProject> project = file.apply(document).map(IFile::getProject);
+		if (project.isPresent()) {
+			return forProject(project.get());
+		}
+		return forExternal(document);
+	}
+
+	private boolean forExternal(IDocument document) {
+		//let's use workspace-level setting
+		PreferenceMetadata<Boolean> option = metadata.preferLanguageServer();
+		return Platform.getPreferencesService().getBoolean(Activator.PLUGIN_ID, option.identifer(),
+				option.defaultValue(), null);
+	}
+
+	private boolean forProject(IProject project) {
+		PreferenceMetadata<Boolean> option = metadata.preferLanguageServer();
+		return Platform.getPreferencesService().getBoolean(Activator.PLUGIN_ID, option.identifer(),
+				option.defaultValue(), new IScopeContext[] { new ProjectScope(project) });
+	}
+
+}

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/internal/core/workspace/ResolveDocumentBuffer.java

@@ -0,0 +1,30 @@
+/*******************************************************************************
+ * Copyright (c) 2020 ArSysOp and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Alexander Fedorov (ArSysOp) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.lsp.internal.core.workspace;
+
+import java.util.Optional;
+import java.util.function.Function;
+
+import org.eclipse.core.filebuffers.FileBuffers;
+import org.eclipse.core.filebuffers.ITextFileBuffer;
+import org.eclipse.jface.text.IDocument;
+
+public final class ResolveDocumentBuffer implements Function<IDocument, Optional<ITextFileBuffer>> {
+
+	@Override
+	public Optional<ITextFileBuffer> apply(IDocument document) {
+		return Optional.ofNullable(document).map(FileBuffers.getTextFileBufferManager()::getTextFileBuffer);
+	}
+
+}

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/internal/core/workspace/ResolveDocumentFile.java

@@ -0,0 +1,40 @@
+/*******************************************************************************
+ * Copyright (c) 2020 ArSysOp and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Alexander Fedorov (ArSysOp) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.lsp.internal.core.workspace;
+
+import java.util.Optional;
+import java.util.function.Function;
+
+import org.eclipse.core.resources.IFile;
+import org.eclipse.core.resources.ResourcesPlugin;
+import org.eclipse.jface.text.IDocument;
+
+public final class ResolveDocumentFile implements Function<IDocument, Optional<IFile>> {
+
+	private final ResolveDocumentPath path;
+
+	public ResolveDocumentFile() {
+		path = new ResolveDocumentPath();
+	}
+
+	@Override
+	public Optional<IFile> apply(IDocument document) {
+		return Optional.ofNullable(document)//
+				.flatMap(path)//
+				.map(ResourcesPlugin.getWorkspace().getRoot()::findMember)//
+				.filter(IFile.class::isInstance)//
+				.map(IFile.class::cast);
+	}
+
+}

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/internal/core/workspace/ResolveDocumentPath.java

@@ -0,0 +1,36 @@
+/*******************************************************************************
+ * Copyright (c) 2020 ArSysOp and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Alexander Fedorov (ArSysOp) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.lsp.internal.core.workspace;
+
+import java.util.Optional;
+import java.util.function.Function;
+
+import org.eclipse.core.filebuffers.ITextFileBuffer;
+import org.eclipse.core.runtime.IPath;
+import org.eclipse.jface.text.IDocument;
+
+public final class ResolveDocumentPath implements Function<IDocument, Optional<IPath>> {
+
+	private final ResolveDocumentBuffer buffer;
+
+	public ResolveDocumentPath() {
+		buffer = new ResolveDocumentBuffer();
+	}
+
+	@Override
+	public Optional<IPath> apply(IDocument document) {
+		return Optional.ofNullable(document).flatMap(buffer).map(ITextFileBuffer::getLocation);
+	}
+
+}

lsp/org.eclipse.cdt.lsp.core/src/org/eclipse/cdt/lsp/internal/core/workspace/ResolveDocumentUri.java

@@ -11,7 +11,7 @@
  * Contributors:
  *     Alexander Fedorov (ArSysOp) - initial API and implementation
  *******************************************************************************/
-package org.eclipse.cdt.lsp.internal.text;
+package org.eclipse.cdt.lsp.internal.core.workspace;
 
 import java.net.URI;
 import java.util.Optional;
@@ -23,11 +23,17 @@ import org.eclipse.lsp4e.LSPEclipseUtils;
 @SuppressWarnings("restriction")
 public final class ResolveDocumentUri implements Function<IDocument, Optional<URI>> {
 
+	private final ResolveDocumentFile file;
+
+	public ResolveDocumentUri() {
+		file = new ResolveDocumentFile();
+	}
+
 	@Override
 	public Optional<URI> apply(IDocument document) {
 		return Optional.ofNullable(document)//
-				//FIXME rewrite involved static utilities and contribute the result back to LSP4E
+				.flatMap(file)//
-				.flatMap(d -> Optional.ofNullable(LSPEclipseUtils.getFile(d)))
+				//FIXME rewrite involved static utilities
 				.flatMap(f -> Optional.ofNullable(LSPEclipseUtils.toUri(f)));
 	}
 

lsp/org.eclipse.cdt.lsp.cquery/src/org/eclipse/cdt/lsp/internal/cquery/ui/PublishSemanticHighlighting.java

@@ -17,9 +17,9 @@ import java.util.function.Consumer;
 
 import org.eclipse.cdt.internal.ui.editor.SemanticHighlightingManager.HighlightedPosition;
 import org.eclipse.cdt.internal.ui.editor.SemanticHighlightingManager.HighlightingStyle;
+import org.eclipse.cdt.lsp.internal.core.workspace.ResolveDocumentUri;
 import org.eclipse.cdt.lsp.internal.cquery.CquerySemanticHighlights;
 import org.eclipse.cdt.lsp.internal.cquery.HighlightSymbol;
-import org.eclipse.cdt.lsp.internal.text.ResolveDocumentUri;
 import org.eclipse.cdt.lsp.internal.ui.text.PresentationReconcilerCPP;
 import org.eclipse.cdt.ui.CUIPlugin;
 import org.eclipse.cdt.ui.PreferenceConstants;

lsp/org.eclipse.cdt.lsp.ui/META-INF/MANIFEST.MF

@@ -7,6 +7,7 @@ Bundle-Name: %Bundle-Name
 Bundle-Vendor: %Bundle-Vendor
 Bundle-RequiredExecutionEnvironment: JavaSE-11
 Require-Bundle: org.eclipse.osgi;bundle-version="[3.15.0,4.0.0)",
+ org.eclipse.core.expressions;bundle-version="3.7.0",
  org.eclipse.core.resources;bundle-version="3.13.800",
  org.eclipse.core.runtime;bundle-version="3.19.0",
  org.eclipse.equinox.preferences;bundle-version="[3.7.0,4.0.0)",

lsp/org.eclipse.cdt.lsp.ui/OSGI-INF/l10n/bundle.properties

@@ -18,3 +18,5 @@ Bundle-Vendor = Eclipse CDT
 preferencePages.languageServer.name=C/C++ Language Server
 
 cDocumentSetupParticipant =C Document Setup Participant
+
+properties.ls.name = C/C++ Language Server

lsp/org.eclipse.cdt.lsp.ui/plugin.xml

@@ -22,6 +22,26 @@
             name="%preferencePages.languageServer.name">
       </page>
    </extension>
+   <extension
+         point="org.eclipse.ui.propertyPages">
+      <page
+            category="org.eclipse.cdt.ui.newui.Page_head_general"
+            class="org.eclipse.cdt.lsp.internal.ui.properties.LanguageServerPropertyPage"
+            id="org.eclipse.cdt.lsp.ui.properties.ls"
+            name="%properties.ls.name">
+         <filter
+               name="projectNature"
+               value="org.eclipse.cdt.core.cnature">
+         </filter>
+         <enabledWhen>
+            <or>
+               <adapt
+                     type="org.eclipse.core.resources.IProject">
+               </adapt>
+            </or>
+         </enabledWhen>
+      </page>
+   </extension>
    <extension
          point="org.eclipse.ui.editors">
       <editorContentTypeBinding
@@ -52,4 +72,14 @@
             contentTypeId="org.eclipse.cdt.lsp.core">
       </participant>
    </extension>
+   <extension
+         point="org.eclipse.core.expressions.propertyTesters">
+      <propertyTester
+            class="org.eclipse.cdt.lsp.internal.ui.expressions.DocumentsTester"
+            id="org.eclipse.cdt.lsp.workspace.documents"
+            namespace="org.eclipse.cdt.lsp.documents"
+            properties="prefer"
+            type="org.eclipse.ui.texteditor.AbstractDecoratedTextEditor">
+      </propertyTester>
+   </extension>
 </plugin>

lsp/org.eclipse.cdt.lsp.ui/src/org/eclipse/cdt/lsp/internal/ui/LspUiMessages.java

@@ -28,6 +28,7 @@ public class LspUiMessages extends NLS {
 	public static String CPPLanguageServerPreferencePage_server_options;
 	public static String CPPLanguageServerPreferencePage_server_path;
 	public static String CPPLanguageServerPreferencePage_server_selector;
+	public static String LanguageServerPropertyPage_w_ls_experimental;
 
 	private LspUiMessages() {
 	}

lsp/org.eclipse.cdt.lsp.ui/src/org/eclipse/cdt/lsp/internal/ui/LspUiMessages.properties

@@ -17,3 +17,4 @@ CPPLanguageServerPreferencePage_description=Preferences for the C/C++ Language S
 CPPLanguageServerPreferencePage_server_options=Command-line options for the server
 CPPLanguageServerPreferencePage_server_path=Path to the server executable
 CPPLanguageServerPreferencePage_server_selector=Please select the C/C++ Language Server you want to use in Eclipse :
+LanguageServerPropertyPage_w_ls_experimental=The C/C++ Language Server support is experimental

lsp/org.eclipse.cdt.lsp.ui/src/org/eclipse/cdt/lsp/internal/ui/expressions/DocumentsTester.java

@@ -0,0 +1,42 @@
+/*******************************************************************************
+ * Copyright (c) 2020 ArSysOp and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Alexander Fedorov (ArSysOp) - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.lsp.internal.ui.expressions;
+
+import org.eclipse.cdt.lsp.internal.core.workspace.PreferLanguageServer;
+import org.eclipse.core.expressions.PropertyTester;
+import org.eclipse.jface.text.IDocument;
+import org.eclipse.ui.texteditor.AbstractDecoratedTextEditor;
+
+public final class DocumentsTester extends PropertyTester {
+
+	private final String key = "prefer"; //$NON-NLS-1$
+	private final PreferLanguageServer predicate;
+
+	public DocumentsTester() {
+		this.predicate = new PreferLanguageServer();
+	}
+
+	@Override
+	public boolean test(Object receiver, String property, Object[] args, Object expectedValue) {
+		if (key.equals(property)) {
+			if (receiver instanceof AbstractDecoratedTextEditor) {
+				AbstractDecoratedTextEditor editor = (AbstractDecoratedTextEditor) receiver;
+				IDocument document = editor.getDocumentProvider().getDocument(editor.getEditorInput());
+				return predicate.test(document);
+			}
+		}
+		return false;
+	}
+
+}

lsp/org.eclipse.cdt.lsp.ui/src/org/eclipse/cdt/lsp/internal/ui/preferences/CPPLanguageServerPreferencePage.java

@@ -25,10 +25,13 @@ import org.eclipse.cdt.lsp.LanguageServerConfiguration;
 import org.eclipse.cdt.lsp.SupportedLanguageServers;
 import org.eclipse.cdt.lsp.core.CPPStreamConnectionProvider;
 import org.eclipse.cdt.lsp.core.PreferenceConstants;
+import org.eclipse.cdt.lsp.internal.core.preferences.LanguageServerDefaults;
 import org.eclipse.cdt.lsp.internal.ui.LspUiActivator;
 import org.eclipse.cdt.lsp.internal.ui.LspUiMessages;
 import org.eclipse.cdt.ui.newui.MultiLineTextFieldEditor;
 import org.eclipse.core.runtime.ServiceCaller;
+import org.eclipse.core.runtime.preferences.PreferenceMetadata;
+import org.eclipse.jface.preference.BooleanFieldEditor;
 import org.eclipse.jface.preference.FieldEditor;
 import org.eclipse.jface.preference.FieldEditorPreferencePage;
 import org.eclipse.jface.preference.FileFieldEditor;
@@ -55,6 +58,8 @@ public class CPPLanguageServerPreferencePage extends FieldEditorPreferencePage i
 
 	@Override
 	public void createFieldEditors() {
+		PreferenceMetadata<Boolean> prefer = new LanguageServerDefaults().preferLanguageServer();
+		addField(new BooleanFieldEditor(prefer.identifer(), prefer.name(), getFieldEditorParent()));
 		serverChoice = new RadioGroupFieldEditor(PreferenceConstants.P_SERVER_CHOICE,
 				LspUiMessages.CPPLanguageServerPreferencePage_server_selector, 1, contributedServers(),
 				getFieldEditorParent());

lsp/org.eclipse.cdt.lsp.ui/src/org/eclipse/cdt/lsp/internal/ui/properties/LanguageServerPropertyPage.java

@@ -0,0 +1,139 @@
+/*******************************************************************************
+ * Copyright (c) 2020 ArSysOp and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Alexander Fedorov <alexander.fedorov@arsysop.ru> - Initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.lsp.internal.ui.properties;
+
+import java.util.Optional;
+
+import org.eclipse.cdt.lsp.core.Activator;
+import org.eclipse.cdt.lsp.core.preferences.LanguageServerPreferenceMetadata;
+import org.eclipse.cdt.lsp.internal.core.preferences.LanguageServerDefaults;
+import org.eclipse.cdt.lsp.internal.ui.LspUiMessages;
+import org.eclipse.core.resources.IProject;
+import org.eclipse.core.resources.ProjectScope;
+import org.eclipse.core.runtime.Platform;
+import org.eclipse.core.runtime.preferences.IEclipsePreferences;
+import org.eclipse.core.runtime.preferences.IScopeContext;
+import org.eclipse.core.runtime.preferences.PreferenceMetadata;
+import org.eclipse.jface.layout.GridDataFactory;
+import org.eclipse.jface.preference.PreferencePage;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.layout.GridData;
+import org.eclipse.swt.layout.GridLayout;
+import org.eclipse.swt.widgets.Button;
+import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Control;
+import org.eclipse.swt.widgets.Label;
+import org.eclipse.ui.dialogs.PropertyPage;
+import org.osgi.framework.FrameworkUtil;
+import org.osgi.service.prefs.BackingStoreException;
+
+public final class LanguageServerPropertyPage extends PropertyPage {
+
+	private LanguageServerPreferenceMetadata metadata;
+	private Button prefer;
+
+	public LanguageServerPropertyPage() {
+		this.metadata = new LanguageServerDefaults();
+	}
+
+	private void addHeaderSection(Composite parent) {
+		Composite composite = createDefaultComposite(parent);
+		Label warning = new Label(composite, SWT.NONE);
+		warning.setText(LspUiMessages.LanguageServerPropertyPage_w_ls_experimental);
+	}
+
+	private void addSeparator(Composite parent) {
+		Label separator = new Label(parent, SWT.SEPARATOR | SWT.HORIZONTAL);
+		GridData gridData = new GridData();
+		gridData.horizontalAlignment = GridData.FILL;
+		gridData.grabExcessHorizontalSpace = true;
+		separator.setLayoutData(gridData);
+	}
+
+	private void addSettingsSection(Composite parent) {
+		PreferenceMetadata<Boolean> option = metadata.preferLanguageServer();
+		Composite composite = createDefaultComposite(parent);
+		prefer = new Button(composite, SWT.CHECK);
+		prefer.setLayoutData(new GridData());
+		prefer.setText(option.name());
+		prefer.setToolTipText(option.description());
+	}
+
+	private void load() {
+		Optional<IProject> project = project();
+		PreferenceMetadata<Boolean> option = metadata.preferLanguageServer();
+		if (project.isPresent()) {
+			prefer.setSelection(Platform.getPreferencesService().getBoolean(Activator.PLUGIN_ID, option.identifer(),
+					option.defaultValue(), new IScopeContext[] { new ProjectScope(project.get()) }));
+		} else {
+			prefer.setSelection(option.defaultValue());
+		}
+	}
+
+	/**
+	 * @see PreferencePage#createContents(Composite)
+	 */
+	@Override
+	protected Control createContents(Composite parent) {
+		Composite composite = new Composite(parent, SWT.NONE);
+		GridLayout layout = new GridLayout();
+		composite.setLayout(layout);
+		GridData data = new GridData(GridData.FILL);
+		data.grabExcessHorizontalSpace = true;
+		composite.setLayoutData(data);
+		addHeaderSection(composite);
+		addSeparator(composite);
+		addSettingsSection(composite);
+		load();
+		return composite;
+	}
+
+	private Composite createDefaultComposite(Composite parent) {
+		Composite composite = new Composite(parent, SWT.NULL);
+		GridLayout layout = new GridLayout();
+		layout.numColumns = 2;
+		composite.setLayout(layout);
+		composite.setLayoutData(GridDataFactory.fillDefaults().create());
+		return composite;
+	}
+
+	@Override
+	protected void performDefaults() {
+		super.performDefaults();
+		prefer.setSelection(metadata.preferLanguageServer().defaultValue());
+	}
+
+	@Override
+	public boolean performOk() {
+		Optional<IProject> project = project();
+		if (project.isPresent()) {
+			IEclipsePreferences node = new ProjectScope(project.get()).getNode(Activator.PLUGIN_ID);
+			node.putBoolean(metadata.preferLanguageServer().identifer(), prefer.getSelection());
+			try {
+				node.flush();
+				return true;
+			} catch (BackingStoreException e) {
+				Platform.getLog(FrameworkUtil.getBundle(getClass())).error(e.getMessage(), e);
+			}
+		}
+		return false;
+	}
+
+	private Optional<IProject> project() {
+		return Optional.ofNullable(getElement())//
+				.filter(IProject.class::isInstance)//
+				.map(IProject.class::cast);
+	}
+
+}

lsp/org.eclipse.cdt.lsp.ui/src/org/eclipse/cdt/lsp/internal/ui/text/PresentationReconcilerCPP.java

@@ -40,7 +40,7 @@ import org.eclipse.cdt.internal.ui.text.CPresentationReconciler;
 import org.eclipse.cdt.internal.ui.text.PartitionDamager;
 import org.eclipse.cdt.internal.ui.text.SingleTokenCScanner;
 import org.eclipse.cdt.internal.ui.text.TokenStore;
-import org.eclipse.cdt.lsp.internal.text.ResolveDocumentUri;
+import org.eclipse.cdt.lsp.internal.core.workspace.ResolveDocumentUri;
 import org.eclipse.cdt.ui.CUIPlugin;
 import org.eclipse.cdt.ui.ILanguageUI;
 import org.eclipse.cdt.ui.text.AbstractCScanner;

lsp/org.eclipse.cdt.lsp.ui/src/org/eclipse/cdt/lsp/internal/ui/text/SetInactiveRegions.java

@@ -15,7 +15,7 @@ import java.util.Optional;
 import java.util.function.BiConsumer;
 import java.util.function.Supplier;
 
-import org.eclipse.cdt.lsp.internal.text.ResolveDocumentUri;
+import org.eclipse.cdt.lsp.internal.core.workspace.ResolveDocumentUri;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.jface.text.BadLocationException;
 import org.eclipse.jface.text.BadPositionCategoryException;