Adding inlay hints in the VS Code extension.

Author: lahodaj

ide/api.lsp/apichanges.xml

@@ -51,6 +51,19 @@
 <!-- ACTUAL CHANGES BEGIN HERE: -->
 
 <changes>
+    <change id="InlayHintsProvider">
+        <api name="LSP_API"/>
+        <summary>Adding InlayHintsProvider</summary>
+        <version major="1" minor="34"/>
+        <date day="9" month="2" year="2025"/>
+        <author login="jlahoda"/>
+        <compatibility binary="compatible" source="compatible" addition="yes" deletion="no" />
+        <description>
+            The <code>InlayHintsProvider</code> is introduced to provide inlay
+            hints for the LSP protocol.
+        </description>
+        <class package="org.netbeans.spi.lsp" name="InlayHintsProvider"/>
+    </change>
     <change id="RegisterLSPServices">
         <api name="LSP_API"/>
         <summary>Adding RegisterLSPServices annotation</summary>

ide/api.lsp/manifest.mf

@@ -1,5 +1,5 @@
 Manifest-Version: 1.0
 OpenIDE-Module: org.netbeans.api.lsp/1
 OpenIDE-Module-Localizing-Bundle: org/netbeans/api/lsp/Bundle.properties
-OpenIDE-Module-Specification-Version: 1.33
+OpenIDE-Module-Specification-Version: 1.34
 AutoUpdate-Show-In-Client: false

ide/api.lsp/src/org/netbeans/api/lsp/InlayHint.java

@@ -0,0 +1,60 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.netbeans.api.lsp;
+
+/**
+ * An inlay hint.
+ *
+ * @since 1.34
+ */
+public class InlayHint {
+    private final Position position;
+    private final String text;
+
+    /**
+     * Create a new instance of InlayHint
+     *
+     * @param position the position where the hint should appear
+     * @param text the text fo the hint
+     */
+    public InlayHint(Position position, String text) {
+        this.position = position;
+        this.text = text;
+    }
+
+    /**
+     * Returns the position of the hint
+     *
+     * @return the position of the hint
+     */
+    public Position getPosition() {
+        return position;
+    }
+
+    /**
+     * Returns the text of the hint
+     *
+     * @return the text of the hint
+     */
+
+    public String getText() {
+        return text;
+    }
+
+}

ide/api.lsp/src/org/netbeans/spi/lsp/InlayHintsProvider.java

@@ -0,0 +1,112 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.netbeans.spi.lsp;
+
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import org.netbeans.api.annotations.common.CheckForNull;
+import org.netbeans.api.annotations.common.NonNull;
+import org.netbeans.api.annotations.common.NullAllowed;
+import org.netbeans.api.lsp.InlayHint;
+import org.netbeans.api.lsp.Range;
+import org.netbeans.spi.editor.mimelookup.MimeLocation;
+import org.openide.filesystems.FileObject;
+import org.openide.util.Parameters;
+
+/**
+ * A provider for code lens for a given document.
+ *
+ * @since 1.34
+ */
+@MimeLocation(subfolderName = "CodeLensProvider")
+public interface InlayHintsProvider {
+
+    /**
+     * Return a set of types of hints supported by this provider.
+     *
+     * The {@code codeLens} method will only be called if at least one
+     * of the hint type is enabled in the settings.
+     *
+     * @return a set of the hint types supported by this provider.
+     */
+    public Set<String> supportedHintTypes();
+
+    /**
+     * Provide {@code CodeLens} for the given document.
+     *
+     * @param doc the document
+     * @return the (future) code lens.
+     */
+    public CompletableFuture<List<? extends InlayHint>> inlayHints(@NonNull Context context);
+
+    /**
+     * Context in which the inlay hints should be evaluated.
+     */
+    public static final class Context {
+        private final @NonNull FileObject file;
+        private final @NullAllowed Range range;
+        private final @NonNull Set<String> requestedHintTypes;
+
+        /**
+         * Create the Context.
+         *
+         * @param file a file in which the inlay hints should be evaluated
+         * @param range the range for which the hints should be computed
+         * @param requestedHintTypes the types of hints that should be computed
+         */
+        public Context(@NonNull FileObject file, @NullAllowed Range range, @NonNull Set<String> requestedHintTypes) {
+            Parameters.notNull("file", file);
+            Parameters.notNull("range", range);
+            Parameters.notNull("requestedHintTypes", requestedHintTypes);
+
+            this.file = file;
+            this.range = range;
+            this.requestedHintTypes = Set.copyOf(requestedHintTypes);
+        }
+
+        /**
+         * The file for which the inlay hints should be computed.
+         *
+         * @return the file for which the inlay hints should be computed
+         */
+        public @NonNull FileObject getFile() {
+            return file;
+        }
+
+        /**
+         * The range for which the inlay hints should be computed.
+         *
+         * @return the range for which the inlay hints should be computed
+         */
+        public @CheckForNull Range getRange() {
+            return range;
+        }
+
+        /**
+         * The types of hints that should be computed.
+         *
+         * @return the types of hints that should be computed
+         */
+        public @NonNull Set<String> getRequestedHintTypes() {
+            return requestedHintTypes;
+        }
+
+    }
+}

java/java.editor.base/src/org/netbeans/modules/java/editor/base/semantic/SemanticHighlighterBase.java

@@ -97,39 +97,6 @@ public abstract class SemanticHighlighterBase extends JavaParserResultTask {
     public static final String JAVA_INLINE_HINT_CHAINED_TYPES = "javaInlineHintChainedTypes"; //NOI18N
     public static final String JAVA_INLINE_HINT_VAR_TYPE = "javaInlineHintVarType"; //NOI18N
 
-    private static final Map<String, Boolean> DEFAULT_VALUES;
-
-    static {
-        Map<String, Boolean> defaultValuesBuilder = new HashMap<>();
-        defaultValuesBuilder.put(JAVA_INLINE_HINT_PARAMETER_NAME, true);
-        defaultValuesBuilder.put(JAVA_INLINE_HINT_CHAINED_TYPES, false);
-        defaultValuesBuilder.put(JAVA_INLINE_HINT_VAR_TYPE, false);
-        DEFAULT_VALUES = Collections.unmodifiableMap(defaultValuesBuilder);
-    }
-
-    private static boolean javaInlineHintParameterName;
-    private static boolean javaInlineHintChainedTypes;
-    private static boolean javaInlineHintVarType;
-
-    private static boolean isJavaInlineHintParameterName() {
-        return javaInlineHintParameterName;
-    }
-
-    private static boolean isJavaInlineHintChainedTypes() {
-        return javaInlineHintChainedTypes;
-    }
-
-    private static boolean isJavaInlineHintVarType() {
-        return javaInlineHintVarType;
-    }
-
-    private static void updateFromPreferences() {
-        Preferences preferences = NbPreferences.root().node("/org/netbeans/modules/java/editor/InlineHints/default");
-        javaInlineHintParameterName = preferences.getBoolean(JAVA_INLINE_HINT_PARAMETER_NAME, DEFAULT_VALUES.get(JAVA_INLINE_HINT_PARAMETER_NAME));
-        javaInlineHintChainedTypes = preferences.getBoolean(JAVA_INLINE_HINT_CHAINED_TYPES, DEFAULT_VALUES.get(JAVA_INLINE_HINT_CHAINED_TYPES));
-        javaInlineHintVarType = preferences.getBoolean(JAVA_INLINE_HINT_VAR_TYPE, DEFAULT_VALUES.get(JAVA_INLINE_HINT_VAR_TYPE));
-    }
-
     private AtomicBoolean cancel = new AtomicBoolean();
 
     protected SemanticHighlighterBase() {
@@ -189,9 +156,11 @@ public Class<? extends Scheduler> getSchedulerClass() {
     protected abstract boolean process(CompilationInfo info, final Document doc);
 
     protected boolean process(CompilationInfo info, final Document doc, ErrorDescriptionSetter setter) {
-        updateFromPreferences();
+        return process(info, doc, Settings.getDefault(), setter);
+    }
 
-        DetectorVisitor v = new DetectorVisitor(info, doc, cancel);
+    protected boolean process(CompilationInfo info, final Document doc, Settings settings, ErrorDescriptionSetter setter) {
+        DetectorVisitor v = new DetectorVisitor(info, doc, settings, cancel);
 
         Map<Token, Coloring> newColoring = new IdentityHashMap<>();
 
@@ -315,8 +284,9 @@ public String toString() {
 
     private static class DetectorVisitor extends CancellableTreePathScanner<Void, Void> {
 
-        private org.netbeans.api.java.source.CompilationInfo info;
-        private Document doc;
+        private final org.netbeans.api.java.source.CompilationInfo info;
+        private final Document doc;
+        private final Settings settings;
         private Map<Element, List<Use>> type2Uses;        
         private Map<Tree, List<Token>> tree2Tokens;
         private List<Token> contextKeywords;
@@ -327,11 +297,12 @@ private static class DetectorVisitor extends CancellableTreePathScanner<Void, Vo
         private SourcePositions sourcePositions;
         private ExecutableElement recursionDetector;
 
-        private DetectorVisitor(org.netbeans.api.java.source.CompilationInfo info, final Document doc, AtomicBoolean cancel) {
+        private DetectorVisitor(org.netbeans.api.java.source.CompilationInfo info, final Document doc, Settings settings, AtomicBoolean cancel) {
             super(cancel);
 
             this.info = info;
             this.doc  = doc;
+            this.settings = settings;
             type2Uses = new HashMap<Element, List<Use>>();
             tree2Tokens = new IdentityHashMap<Tree, List<Token>>();
             contextKeywords = new ArrayList<>();
@@ -787,7 +758,7 @@ public Void visitMethodInvocation(MethodInvocationTree tree, Void p) {
         }
 
         private void addChainedTypes(TreePath current) {
-            if(! isJavaInlineHintChainedTypes()) {
+            if (!settings.javaInlineHintChainedTypes) {
                 return;
             }
             List<TreePath> chain = new ArrayList<>(); //TODO: avoid creating an instance if possible!
@@ -963,7 +934,7 @@ public Void visitVariable(VariableTree tree, Void p) {
 
             tl.moveNext();
 
-            if (info.getTreeUtilities().isVarType(getCurrentPath()) && isJavaInlineHintVarType()) {
+            if (info.getTreeUtilities().isVarType(getCurrentPath()) && settings.javaInlineHintVarType) {
                 int afterName = tl.offset();
                 TypeMirror type = info.getTrees().getTypeMirror(new TreePath(getCurrentPath(), tree.getType()));
 
@@ -1156,7 +1127,7 @@ private int leadingIndent(String line) {
         }
 
         private void addParameterInlineHint(Tree tree) {
-            if(! isJavaInlineHintParameterName()) {
+            if (!settings.javaInlineHintParameterName) {
                 return;
             }
             TreePath pp = getCurrentPath().getParentPath();
@@ -1197,5 +1168,35 @@ public static interface ErrorDescriptionSetter {
 
         public void setHighlights(Document doc, Collection<Pair<int[], Coloring>> highlights, Map<int[], String> preText);
         public void setColorings(Document doc, Map<Token, Coloring> colorings);
-    }    
+    }
+
+    public static class Settings {
+        private static final Map<String, Boolean> DEFAULT_VALUES;
+
+        static {
+            Map<String, Boolean> defaultValuesBuilder = new HashMap<>();
+            defaultValuesBuilder.put(JAVA_INLINE_HINT_PARAMETER_NAME, true);
+            defaultValuesBuilder.put(JAVA_INLINE_HINT_CHAINED_TYPES, false);
+            defaultValuesBuilder.put(JAVA_INLINE_HINT_VAR_TYPE, false);
+            DEFAULT_VALUES = Collections.unmodifiableMap(defaultValuesBuilder);
+        }
+
+        public final boolean javaInlineHintParameterName;
+        public final boolean javaInlineHintChainedTypes;
+        public final boolean javaInlineHintVarType;
+
+        public Settings(boolean javaInlineHintParameterName, boolean javaInlineHintChainedTypes, boolean javaInlineHintVarType) {
+            this.javaInlineHintParameterName = javaInlineHintParameterName;
+            this.javaInlineHintChainedTypes = javaInlineHintChainedTypes;
+            this.javaInlineHintVarType = javaInlineHintVarType;
+        }
+
+        public static Settings getDefault() {
+            Preferences preferences = NbPreferences.root().node("/org/netbeans/modules/java/editor/InlineHints/default");
+            return new Settings(preferences.getBoolean(JAVA_INLINE_HINT_PARAMETER_NAME, DEFAULT_VALUES.get(JAVA_INLINE_HINT_PARAMETER_NAME)),
+                                preferences.getBoolean(JAVA_INLINE_HINT_CHAINED_TYPES, DEFAULT_VALUES.get(JAVA_INLINE_HINT_CHAINED_TYPES)),
+                                preferences.getBoolean(JAVA_INLINE_HINT_VAR_TYPE, DEFAULT_VALUES.get(JAVA_INLINE_HINT_VAR_TYPE)));
+        }
+
+    }
 }