LSPApi.md

LSP Client Features

The LSPClientFeatures API allows you to customize the behavior of LSP features, including:

• LSP codeAction feature
• LSP codeLens feature
• LSP color feature
• LSP completion feature
• LSP declaration feature
• LSP definition feature
• LSP diagnostic feature
• LSP documentHighlight feature
• LSP documentLink feature
• LSP documentSymbol feature
• LSP foldingRange feature
• LSP formatting feature
• LSP selection feature
• LSP hover feature
• LSP implementation feature
• LSP inlayHint feature
• LSP references feature
• LSP rename feature
• LSP semanticTokens feature
• LSP signatureHelp feature
• LSP typeDefinition feature
• LSP usage feature
• LSP workspace symbol feature

You can extend these default features by:

• Creating custom classes that extend the LSP*Feature classes (e.g., creating a class MyLSPFormattingFeature that extends the LSPFormattingFeature to customize formatting support) and overriding specific methods to modify behavior.
• Registering your custom classes using LanguageServerFactory#createClientFeatures().

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() {
        return new LSPClientFeatures()
                .setCompletionFeature(new MyLSPCompletionFeature()) // customize LSP completion feature
                .setDiagnosticFeature(new MyLSPDiagnosticFeature()) // customize LSP diagnostic feature
                .setFormattingFeature(new MyLSPFormattingFeature()); // customize LSP formatting feature         
    }
}

API	Description	Default Behaviour
Project getProject()	Returns the project.
LanguageServerDefinition getServerDefinition()	Returns the language server definition.
boolean isServerDefinition(@NotNull String languageServerId)	Returns true if the given language server id matches the server definition and false otherwise.
ServerStatus getServerStatus()	Returns the server status.
LanguageServer getLanguageServer()	Returns the LSP4J language server.
boolean keepServerAlive()	Returns true if the server is kept alive even if all files associated with the language server are closed and false otherwise.	false
boolean canStopServerByUser()	Returns true if the user can stop the language server in LSP console from the context menu and false otherwise.	true
boolean isEnabled(VirtualFile)	Returns true if the language server is enabled for the given file and false otherwise.	true
boolean isCaseSensitive(PsiFile file)	Returns true if the language grammar for the given file is case-sensitive and false otherwise.	false

package my.language.server;

import com.redhat.devtools.lsp4ij.client.features.LSPClientFeatures;

public class MyLSPClientFeatures extends LSPClientFeatures {

    @Override
    public boolean keepServerAlive() {
        // Kept alive the server even if all files associated with the language server are closed
        return true;
    }
}

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() {
        return new MyLSPClientFeatures() // customize LSP general features
                .setCompletionFeature(new MyLSPCompletionFeature()) // customize LSP completion feature
                .setDiagnosticFeature(new MyLSPDiagnosticFeature()) // customize LSP diagnostic feature
                .setFormattingFeature(new MyLSPFormattingFeature()); // customize LSP formatting feature         
    }
}

LSP Base Feature

API	Description	Default Behaviour
Project getProject()	Returns the project.
LanguageServerDefinition getServerDefinition()	Returns the language server definition.
boolean isServerDefinition(@NotNull String languageServerId)	Returns true if the given language server id matches the server definition and false otherwise.
ServerStatus getServerStatus()	Returns the server status.
LanguageServer getLanguageServer()	Returns the LSP4J language server.

Disable a given LSP Feature

All LSP*Feature classes extend AbstractLSPDocumentFeature, which declares the isEnabled method that returns true by default:

public boolean isEnabled(@NotNull PsiFile file) {
    return true;
}

By overriding this method, you can return false to disable a given LSP feature for your language server. This method is called before starting the language server.

Supported LSP Feature

All LSP*Feature classes extend AbstractLSPDocumentFeature, which declares the isSupported method that uses the server capabilities:

public boolean isSupported(@NotNull PsiFile file) {

}

This method is called after starting the language server to collect the LSP server capabilities.

Project Access

If you need the Project instance in your LSP feature to retrieve the settings of the current project, you can use the getProject() getter method.

public class MyLSPCodeLensFeature extends LSPCodeLensFeature {

    @Override
    public boolean isEnabled(@NotNull PsiFile file) {
        return MySettings.getInstance(super.getProject()).isCodeLensEnabled();
    }

}

Server Status

If you need to check the server status, you can use the getServerStatus() getter method.

public class MyLSPCodeLensFeature extends LSPCodeLensFeature {

    @Override
    public boolean isEnabled(@NotNull PsiFile file) {
        // Here, code lens will be disabled if the language server is not started
        // (the LSP CodeLens will not force the start of the language server)
        var serverStatus = super.getServerStatus();
        return serverStatus == ServerStatus.starting || serverStatus == ServerStatus.started;
    }

}

LSP CodeAction Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability
String getText(CodeAction codeAction)	Returns the IntelliJ intention action text from the given LSP code action and null to ignore the code action.	codeAction.getTitle()
String getFamilyName(CodeAction codeAction)	Returns the IntelliJ intention action family name from the given LSP code action.	Label of CodeActionKind
String getText(Command command)	Returns the IntelliJ intention action text from the given LSP command and null to ignore the command.	command.getTitle()
String getFamilyName(Command command)	Returns the IntelliJ intention action family name from the given LSP command.	"LSP Command"

LSP CodeLens Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability
CodeVisionEntry createCodeVisionEntry(CodeLens codeLens, String providerId, LSPCodeLensContext codeLensContext)	Creates an IntelliJ CodeVisionEntry from the given LSP CodeLens and null otherwise (to ignore the LSP CodeLens).
String getText(CodeLens codeLens)	Returns the code vision entry text from the LSP CodeLens and null otherwise (to ignore the LSP CodeLens).	codeLens.getCommand().getTitle()

Here is an example of code that avoids creating an IntelliJ CodeVisionEntry when the LSP CodeLens command is equal to Run:

package my.language.server;

import com.redhat.devtools.lsp4ij.client.features.LSPCodeLensFeature;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

public class MyLSPCodeLensFeature extends LSPCodeLensFeature {

    @Override
    @Nullable
    public String getText(CodeLens codeLens) {
        Command command = codeLens.getCommand();
        if ("Run".equals(command)) {
            return null;
        }
        return super.getText(codeLens);
    }

}

LSP Color Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP Completion Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability
LookupElement createLookupElement(CompletionItem item, LSPCompletionContext context)	Create a completion lookup element from the given LSP completion item and context and null otherwise.
void renderLookupElement(LookupElementPresentation presentation, CompletionItem item)	Update the given IntelliJ lookup element presentation with the given LSP completion item.
String getItemText(CompletionItem item)	Returns the IntelliJ lookup item text from the given LSP completion item and null otherwise.	item.getLabel()
String getTypeText(CompletionItem item)	Returns the IntelliJ lookup type text from the given LSP completion item and null otherwise.	item.getDetail()
Icon getIcon(CompletionItem item)	Returns the IntelliJ lookup icon from the given LSP completion item and null otherwise.	default icon from item.getKind()
boolean isStrikeout(CompletionItem item)	Returns true if the IntelliJ lookup is strike out and false otherwise.	use item.getDeprecated() or item.getTags().contains(CompletionItemTag.Deprecated)
String getTailText(CompletionItem item)	Returns the IntelliJ lookup tail text from the given LSP completion item and null otherwise.	item.getLabelDetails().getDetail()
boolean isItemTextBold(CompletionItem item)	Returns the IntelliJ lookup item text bold from the given LSP completion item and null otherwise.	item.getKind() == CompletionItemKind.Keyword

|

LSP Declaration Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP Definition Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP Diagnostic Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
void createAnnotation(Diagnostic diagnostic, Document document, List fixes, AnnotationHolder holder)	Creates an IntelliJ annotation in the given holder using the provided LSP diagnostic and fixes.
HighlightSeverity getHighlightSeverity(Diagnostic diagnostic)	Returns the IntelliJ HighlightSeverity from the given diagnostic and null otherwise.
String getMessage(Diagnostic diagnostic)	Returns the message of the given diagnostic.
String getToolTip(Diagnostic diagnostic)	Returns the annotation tooltip from the given LSP diagnostic.
ProblemHighlightType getProblemHighlightType(List tags)	Returns the ProblemHighlightType from the given tags and null otherwise.

Here is an example of code that avoids creating an IntelliJ annotation when the LSP diagnostic code is equal to ignore:

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);
    }

}

LSP DocumentHighlight Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP DocumentLink Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP DocumentSymbol Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability
StructureViewTreeElement getStructureViewTreeElement(DocumentSymbolData documentSymbol)
String getPresentableText(DocumentSymbol documentSymbol, PsiFile psiFile)
Icon getIcon(DocumentSymbol documentSymbol, PsiFile psiFile)
String getPresentableText(DocumentSymbol documentSymbol, PsiFile psiFile, boolean unused)
void navigate(DocumentSymbol documentSymbol, PsiFile psiFile, boolean requestFocus)
boolean canNavigate(DocumentSymbol documentSymbol, PsiFile psiFile)

Here is an example of code to customize the document symbol used in Structure:

package com.redhat.devtools.lsp4ij.client;

import com.intellij.ide.structureView.StructureViewTreeElement;
import com.intellij.psi.PsiFile;
import com.redhat.devtools.lsp4ij.client.features.LSPDocumentSymbolFeature;
import com.redhat.devtools.lsp4ij.features.documentSymbol.DocumentSymbolData;
import org.eclipse.lsp4j.DocumentSymbol;
import org.eclipse.lsp4j.SymbolKind;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import javax.swing.*;

public class MyLSPDocumentSymbolFeature extends LSPDocumentSymbolFeature {

    @Override
    public @Nullable StructureViewTreeElement getStructureViewTreeElement(DocumentSymbolData documentSymbol) {
        if ("ignore".equals(documentSymbol.getDocumentSymbol().getName())) {
            // Ignore document symbol with "ignore" name.
            return null;
        }
        return super.getStructureViewTreeElement(documentSymbol);
    }

    @Override
    public @Nullable Icon getIcon(@NotNull DocumentSymbol documentSymbol, @NotNull PsiFile psiFile, boolean unused) {
        if (documentSymbol.getKind() == SymbolKind.Class) {
            // Returns custom icon for 'Class' symbol kind
            return ...;
        }
        return super.getIcon(documentSymbol, psiFile, unused);
    }

    @Override
    public @Nullable String getPresentableText(@NotNull DocumentSymbol documentSymbol, @NotNull PsiFile psiFile) {
        if (documentSymbol.getKind() == SymbolKind.Class) {
            // Returns custom presentable text for 'Class' symbol kind
            return ...;
        }
        return super.getPresentableText(documentSymbol, psiFile);
    }

    @Override
    public @Nullable String getLocationString(@NotNull DocumentSymbol documentSymbol, @NotNull PsiFile psiFile) {
        if (documentSymbol.getKind() == SymbolKind.Class) {
            // Returns custom location string for 'Class' symbol kind
            return ...;
        }
        return super.getLocationString(documentSymbol, psiFile);
    }
}

LSP FoldingRange Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP Formatting Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability
boolean isExistingFormatterOverrideable(PsiFile file)	Returns true if existing formatters are overrideable and false otherwise.	false

Here is an example of code that allows executing the LSP formatter even if there is a specific formatter registered by an IntelliJ plugin:

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
    protected boolean isExistingFormatterOverrideable(@NotNull PsiFile file) {
        // By default, isExistingFormatterOverrideable returns false if it has a custom formatter with psi
        // returns true even if there is a custom formatter
        return true;
    }
}

LSP Selection Feature

Integrates the LSP textDocument/selectionRange feature.

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP Hover Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability
String getContent(MarkupContent content, PsiFile file)	Returns the HTML content from the given LSP Markup content and null otherwise.

LSP Implementation Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP InlayHint Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP References Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP Rename Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP SemanticTokens Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability
TextAttributesKey getTextAttributesKey(@NotNull String tokenType, List tokenModifiers, PsiFile file)	Returns the TextAttributesKey to use for colorization for the given token type and given token modifiers and null otherwise.

package my.language.server;

import com.intellij.psi.PsiFile;
import com.redhat.devtools.lsp4ij.client.features.LSPSemanticTokensFeature;
import org.jetbrains.annotations.NotNull;

public class MyLSPSemanticTokensFeature extends LSPSemanticTokensFeature {

    @Override
    public @Nullable TextAttributesKey getTextAttributesKey(@NotNull String tokenType,
                                                            @NotNull List<String> tokenModifiers,
                                                            @NotNull PsiFile file) {
        if ("myClass".equals(tokenType)) {
            TextAttributesKey myClass = ...
            return myClass;
        }
        if ("ignore".equals(tokenType)) {
            return null;
        }
        return super.getTextAttributesKey(tokenType, tokenModifiers, file);
    }
}

LSP SignatureHelp Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP TypeDefinition Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP Usage Feature

API	Description	Default Behaviour
boolean isEnabled(PsiFile file)	Returns true if the LSP feature is enabled for the given file and false otherwise.	true
boolean isSupported(PsiFile file)	Returns true if the LSP feature is supported for the given file and false otherwise. This supported state is called after starting the language server, which matches the file and user with the LSP server capabilities.	Check the server capability

LSP Workspace Symbol Feature

API	Description	Default Behaviour
boolean isEnabled()	Returns true if the LSP feature is enabled and false otherwise.	true when server is starting/started
boolean isSupported()	Returns true if the LSP feature is supported and false otherwise. This supported state is called after starting the language server, which matches the LSP server capabilities.	Check the server capability
boolean supportsGotoClass()	Returns true if the LSP feature is efficient enough to support the IDE's Go To Class action which may be invoked frequently and false otherwise.	false