feat: provide LSP API support

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

docs/LSPApi.md

@@ -0,0 +1,92 @@
+# LSP client features
+
+The [LSPClientFeatures](https://github.com/redhat-developer/lsp4ij/blob/main/src/main/java/com/redhat/devtools/lsp4ij/client/features/LSPClientFeatures.java) API allows customizing the behavior of LSP features to customize:
+
+* [LSP completion feature](#customize-lsp-completion-feature)
+* [LSP diagnostic feature](#customize-lsp-diagnostic-feature)
+* [LSP formatting feature](#customize-lsp-formatting-feature)
+
+These custom supports are done:
+
+* by extending the default classes `LSP*Feature` (e.g. creating a new class `MyLSPFormattingFeature` that extends 
+[LSPFormattingFeature](https://github.com/redhat-developer/lsp4ij/blob/main/src/main/java/com/redhat/devtools/lsp4ij/client/features/LSPFormattingFeature.java) to customize formatting support)
+and overriding some methods to customize the behavior.
+* registering your custom classes with `LanguageServerFactory#createClientFeatures(@NotNull Project)`:
+
+```java
+package my.language.server;
+
+import com.intellij.openapi.project.Project;
+import com.redhat.devtools.lsp4ij.LanguageServerFactory;
+import com.redhat.devtools.lsp4ij.client.features.LSPClientFeatures;
+import org.jetbrains.annotations.NotNull;
+
+public class MyLanguageServerFactory implements LanguageServerFactory {
+
+    @Override
+    public @NotNull LSPClientFeatures createClientFeatures(@NotNull Project project) {
+        return new LSPClientFeatures(project)
+                .setCompletionFeature(new MyLSPCompletionFeature()) // customize LSP completion feature
+                .setDiagnosticFeature(new MyLSPDiagnosticFeature()) // customize LSP diagnostic feature
+                .setFormattingFeature(new MyLSPFormattingFeature()); // customize LSP formatting feature         
+    }
+}
+```
+
+## Customize LSP completion feature
+
+TODO
+
+## Customize LSP diagnostic feature
+
+Here is an example of code that avoids creating an IntelliJ annotation when the LSP diagnostic code is equal to `ignore`:
+
+```java
+package my.language.server;
+
+import com.intellij.lang.annotation.HighlightSeverity;
+import com.redhat.devtools.lsp4ij.client.features.LSPDiagnosticFeature;
+import org.eclipse.lsp4j.Diagnostic;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class MyLSPDiagnosticFeature extends LSPDiagnosticFeature {
+
+    @Override
+    public @Nullable HighlightSeverity getHighlightSeverity(@NotNull Diagnostic diagnostic) {
+        if (diagnostic.getCode() != null &&
+                diagnostic.getCode().isLeft() &&
+                "ignore".equals(diagnostic.getCode().getLeft())) {
+            // return a null HighlightSeverity when LSP diagnostic code is equals
+            // to 'ignore' to avoid creating an IntelliJ annotation
+            return null;
+        }
+        return super.getHighlightSeverity(diagnostic);
+    }
+
+}
+```
+
+## Customize LSP formatting feature
+
+Here is an example of code that allows to execute the LSP formatter even if there is a specific formatter registered by an IntelliJ plugin
+
+TODO: revisit this API to manage range formatting too.
+
+```java
+package my.language.server;
+
+import com.intellij.psi.PsiFile;
+import com.redhat.devtools.lsp4ij.client.features.LSPFormattingFeature;
+import org.jetbrains.annotations.NotNull;
+
+public class MyLSPFormattingFeature extends LSPFormattingFeature {
+
+    @Override
+    public boolean canSupportFormatting(@NotNull PsiFile file, boolean hasCustomFormatter) {
+        // By default, LSPCustomizedFormattingSupport return false if it has custom formatter with psi
+        // returns true even if there is custom formatter
+        return true;
+    }
+}
+```

src/main/java/com/redhat/devtools/lsp4ij/LanguageServerFactory.java

@@ -13,6 +13,7 @@
 import com.intellij.openapi.project.Project;
 import com.redhat.devtools.lsp4ij.client.LanguageClientImpl;
 import com.redhat.devtools.lsp4ij.server.StreamConnectionProvider;
+import com.redhat.devtools.lsp4ij.client.features.LSPClientFeatures;
 import org.eclipse.lsp4j.services.LanguageServer;
 import org.jetbrains.annotations.NotNull;
 
@@ -50,4 +51,7 @@ public interface LanguageServerFactory {
         return LanguageServer.class;
     }
 
+    @NotNull default LSPClientFeatures createClientFeatures(@NotNull Project project) {
+        return new LSPClientFeatures(project);
+    }
 }

src/main/java/com/redhat/devtools/lsp4ij/LanguageServerWrapper.java

@@ -31,6 +31,7 @@
 import com.redhat.devtools.lsp4ij.lifecycle.LanguageServerLifecycleManager;
 import com.redhat.devtools.lsp4ij.lifecycle.NullLanguageServerLifecycleManager;
 import com.redhat.devtools.lsp4ij.server.*;
+import com.redhat.devtools.lsp4ij.client.features.LSPClientFeatures;
 import com.redhat.devtools.lsp4ij.server.definition.LanguageServerDefinition;
 import org.eclipse.lsp4j.*;
 import org.eclipse.lsp4j.jsonrpc.Launcher;
@@ -108,6 +109,8 @@ public class LanguageServerWrapper implements Disposable {
 
     private FileOperationsManager fileOperationsManager;
 
+    private LSPClientFeatures clientFeatures;
+
     /* Backwards compatible constructor */
     public LanguageServerWrapper(@NotNull Project project, @NotNull LanguageServerDefinition serverDefinition) {
         this(project, serverDefinition, null);
@@ -1174,4 +1177,11 @@ public boolean isSignatureTriggerCharactersSupported(String charTyped) {
         }
         return triggerCharacters.contains(charTyped);
     }
+
+    public LSPClientFeatures getClientFeatures() {
+        if (clientFeatures == null) {
+            clientFeatures = getServerDefinition().createClientFeatures(getProject());
+        }
+        return clientFeatures;
+    }
 }

src/main/java/com/redhat/devtools/lsp4ij/client/features/AbstractLSPFeature.java

@@ -0,0 +1,42 @@
+/*******************************************************************************
+ * Copyright (c) 2024 Red Hat, Inc.
+ * Distributed under license by Red Hat, Inc. All rights reserved.
+ * This program is made available under the terms of the
+ * Eclipse Public License v2.0 which accompanies this distribution,
+ * and is available at https://www.eclipse.org/legal/epl-v20.html
+ *
+ * Contributors:
+ * Red Hat, Inc. - initial API and implementation
+ ******************************************************************************/
+package com.redhat.devtools.lsp4ij.client.features;
+
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Abstract class for any LSP feature.
+ */
+@ApiStatus.Experimental
+public abstract class AbstractLSPFeature {
+
+    private LSPClientFeatures clientFeatures;
+
+    /**
+     * Returns the LSP server support.
+     *
+     * @return the LSP server support.
+     */
+    public @NotNull LSPClientFeatures getClientFeatures() {
+        return clientFeatures;
+    }
+
+    /**
+     * Set the LSP server support.
+     *
+     * @param clientFeatures the LSP client features.
+     */
+    public void setClientFeatures(@NotNull LSPClientFeatures clientFeatures) {
+        this.clientFeatures = clientFeatures;
+    }
+
+}

src/main/java/com/redhat/devtools/lsp4ij/client/features/LSPClientFeatures.java

@@ -0,0 +1,118 @@
+/*******************************************************************************
+ * Copyright (c) 2024 Red Hat, Inc.
+ * Distributed under license by Red Hat, Inc. All rights reserved.
+ * This program is made available under the terms of the
+ * Eclipse Public License v2.0 which accompanies this distribution,
+ * and is available at https://www.eclipse.org/legal/epl-v20.html
+ *
+ * Contributors:
+ * Red Hat, Inc. - initial API and implementation
+ ******************************************************************************/
+package com.redhat.devtools.lsp4ij.client.features;
+
+import com.intellij.openapi.project.Project;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * LSP  client features.
+ */
+@ApiStatus.Experimental
+public class LSPClientFeatures {
+
+    private final @NotNull Project project;
+
+    private LSPCompletionFeature completionFeature;
+
+    private LSPDiagnosticFeature diagnosticFeature;
+
+    private LSPFormattingFeature formattingFeature;
+
+    public LSPClientFeatures(@NotNull Project project) {
+        this.project = project;
+    }
+
+    /**
+     * Returns the project.
+     *
+     * @return the project.
+     */
+    public @NotNull Project getProject() {
+        return project;
+    }
+
+    /**
+     * Returns the LSP completion feature.
+     *
+     * @return the LSP completion feature.
+     */
+    @NotNull
+    public final LSPCompletionFeature getCompletionFeature() {
+        if (completionFeature == null) {
+            setCompletionFeature(new LSPCompletionFeature());
+        }
+        return completionFeature;
+    }
+
+    /**
+     * Initialize the LSP completion feature.
+     *
+     * @param completionFeature the LSP completion feature.
+     * @return the LSP client features.
+     */
+    public final LSPClientFeatures setCompletionFeature(@NotNull LSPCompletionFeature completionFeature) {
+        completionFeature.setClientFeatures(this);
+        this.completionFeature = completionFeature;
+        return this;
+    }
+
+    /**
+     * Returns the LSP diagnostic feature.
+     *
+     * @return the LSP diagnostic feature.
+     */
+    @NotNull
+    public final LSPDiagnosticFeature getDiagnosticFeature() {
+        if (diagnosticFeature == null) {
+            setDiagnosticFeature(new LSPDiagnosticFeature());
+        }
+        return diagnosticFeature;
+    }
+
+    /**
+     * Initialize the LSP diagnostic feature.
+     *
+     * @param diagnosticFeature the LSP diagnostic feature.
+     * @return the LSP client feature.
+     */
+    public LSPClientFeatures setDiagnosticFeature(@NotNull LSPDiagnosticFeature diagnosticFeature) {
+        diagnosticFeature.setClientFeatures(this);
+        this.diagnosticFeature = diagnosticFeature;
+        return this;
+    }
+
+    /**
+     * Returns the LSP formatting feature.
+     *
+     * @return the LSP formatting feature.
+     */
+    @NotNull
+    public final LSPFormattingFeature getFormattingFeature() {
+        if (formattingFeature == null) {
+            setFormattingFeature(new LSPFormattingFeature());
+        }
+        return formattingFeature;
+    }
+
+    /**
+     * Initialize the LSP formatting feature.
+     *
+     * @param formattingFeature the LSP formatting feature.
+     * @return the LSP client features.
+     */
+    public final LSPClientFeatures setFormattingFeature(@NotNull LSPFormattingFeature formattingFeature) {
+        formattingFeature.setClientFeatures(this);
+        this.formattingFeature = formattingFeature;
+        return this;
+    }
+}

src/main/java/com/redhat/devtools/lsp4ij/client/features/LSPCompletionFeature.java

@@ -0,0 +1,21 @@
+/*******************************************************************************
+ * Copyright (c) 2024 Red Hat, Inc.
+ * Distributed under license by Red Hat, Inc. All rights reserved.
+ * This program is made available under the terms of the
+ * Eclipse Public License v2.0 which accompanies this distribution,
+ * and is available at https://www.eclipse.org/legal/epl-v20.html
+ *
+ * Contributors:
+ * Red Hat, Inc. - initial API and implementation
+ ******************************************************************************/
+package com.redhat.devtools.lsp4ij.client.features;
+
+import org.jetbrains.annotations.ApiStatus;
+
+/**
+ * LSP completion feature.
+ */
+@ApiStatus.Experimental
+public class LSPCompletionFeature extends AbstractLSPFeature {
+
+}