Language Server Extensions Handbook (2023)

As you saw inFeatures of the programming languagesubject, it is possible to implement language functions by direct usetalen.*API. However, the Language Server extension provides an alternative way to implement such language support.

Subjects:

Why one language server?

A language server is a special type of Visual Studio Code extension that allows editing in many programming languages. Language servers allow you to implement auto-completion, error checking (diagnosis), jumping to definitions, and morelinguistic featuressupported in VS Code.

However, when implementing support for language features in VS Code, we found three common problems:

First, language servers are usually implemented in their own programming languages, which makes it challenging to integrate with VS Code that has a Node.js runtime.

Additionally, language features can be quite resource intensive. For example, to properly validate a file, the language server must parse a large number of files, build abstract syntax trees for them, and perform static program analysis. These operations can be CPU and memory intensive, so we need to make sure that VS code performance is intact.

Finally, integrating multiple language tools with multiple code editors can require significant effort. From a language tools perspective, they need to adapt to code editors with different APIs. From the perspective of code editors, they cannot expect a unified API from language tools. This allows implementation of language support forMLanguagesNcode editor workM*N.

To solve these problems, Microsoft gave upLanguage Server Protocol, which standardizes communication between language tools and code editors. In this way, language servers can be implemented in any language and run in their own process to avoid additional overhead when communicating with the code editor via the language server protocol. In addition, all LSP-compatible language tools integrate with many LSP-compatible code editors, and all LSP-compatible code editors can easily use many LSP-compatible language tools. LSP is a win-win for both language tool providers and code editor providers!

Language Server Extensions Handbook (1)

In this guide:

  • Explain how to create a language server extension in VS Code using the attached fileNode SDK.
  • Explain how to run, debug, register, and test a language server extension.
  • List some advanced topics on language servers.

Language server implementation

Review

In VS Code, the language server consists of two parts:

  • Language Client: A regular VS Code extension written in JavaScript/TypeScript. This extension has access to everyoneVS Code namespace API.
  • Language Server: A language analysis tool that runs in a separate process.

As briefly mentioned above, there are two advantages to running the language server in a separate process:

  • The analysis tool can be implemented in any language as long as it can communicate with the language client according to the language server protocol.
  • Because language parsing tools are often CPU and memory intensive, running them in a separate process avoids performance overhead.

Here is an illustration from VS Code with two server language extensions. The HTML client and PHP client are regular VS Code extensions written in TypeScript. Each of them creates a corresponding language server and communicates with it via LSP. Although the PHP server is written in PHP, it can still communicate with the PHP client via LSP.

Language Server Extensions Handbook (2)

(Video) Extending VSCode: Write Your Own Language Server in VSCode

This tutorial will teach you how to build a language client/server using ourNode SDK. The rest of the document assumes you know VS codeExtension-API.

LSP example - a simple language server for plain text files

Let's make a simple language server extension that implements auto-completion and diagnostics for plain text files. We will also discuss configuration synchronization between the client and the server.

If you prefer to go directly to the code:

  • lsp example: Richly documented source code for this guide.
  • lsp-pattern-many-servers: A heavily documented advanced versionlsp examplewhich starts a second server instance per workspace map for maintenancemulti-root workspacefunction in VS code.

Clone the repositoryMicrosoft/vscode extension examplesand open the example:

> clone git https://github.com/microsoft/vscode-extension-samples.git>CDvscode-extension-samples/lsp-uzorak> install npm> npm run-build> the code.

The above installs all dependencies and opens the filelsp exampleworkspace with client and server code. Here is a rough outline of the structurelsp example:

.├── client // Language client│ ├── src│ │ ├── test // Comprehensive tests for Language client / server│ │ └── extension.ts // Language client entry point├── package. json // Extension manifest └── server // Language server └── src └── server.ts // Language server entry point

Explanation of "Language Client".

Let's see first/pakiet.jsonwhich describes the capabilities of the language client. There are two interesting sections:

Look firstconfigurationSection:

"configuration": { "tip":"object", "title":"Sample Configuration", "assets": { „languageServerExample.maxNumberOfProblems”: { "reach":"blush", "tip":"number", "standard":100, "description":"Controls the largest number of server-generated problems."}}}

This section contributesconfigurationsettings for VS code. The example explains how these settings are sent to the language server at startup and when the settings are changed.

Remark: If your extension is compatible with VS Code versions older than 1.74.0, you must check thisonLanguage: clear textwactivation eventsSometimes/pakiet.jsontell VS Code to activate the extension as soon as a plain text file is opened (for example, a file with a.text):

"Activation Events": []

The actual source code of the language client and associatedpacked.jsonare in/Clientfile. Interesting piece inside/client/pakket.jsonthe file it points toeverywhere, everywhereextension of host-API viamotorfield and adds a dependency to the filevscode-taalclientlibrary:

"motor": { „vscode”:„^ 1,52,0”},"addiction": { "vscode-taalclient":„^7.0.0”}

As mentioned, the client is implemented as a regular VS Code extension and has access to all VS Code namespace APIs.

Below is the content of the corresponding extension.ts file, which is the file entrylsp exampleextension:

import * How pad z 'substrate';import{field,Extension context}z „vscode”;import{ LanguageClient, LanguageClientOptions, Server Options, Type of transport}z „vscode-taalclient/čvor”;allow Client:LanguageClient;export function Activate(context:Extension context) { // The server is implemented in the node allow server module=context.as an absolute path(pad.taking part('server','vani',"server.js")); // Server debugging options // --inspect=6009: Start the server in Node Inspector mode to allow VS Code to connect to the server for debugging allow debugging capabilities= {execArgv:['--his','--inspection=6009']}; // If the extension is running in debug mode, the debug server options are used // Otherwise the boot options are used allow Server Options:Server Options= { start:{module: server module,transport: Type of transport.ipc}, debug:{ module: server module, transport: Type of transport.ipc, options: debugging capabilities}}; // Language client control options allow customer options:LanguageClientOptions= { // Register the text document server Documentkiezer:[{diagram: 'duration',Tong: "plain text"}], synchronization:{ // Notify the server about changes to the ".clientrc" files in the workspace event file: field.Create a file system watcher('**/.clientrc')}}; // Create the language client and start the client. Client=novi LanguageClient( "languageServerExample", "Language server example", Server Options, customer options); // Starting the client. This will also start the server Client.start();}export function deactivate():That is possible<vacuum> |indefinite{ I(!Client) { yield indefinite;} yield Client.Stop();}

Explanation of "Language server"

Remark:The "Server" implementation cloned from the GitHub repository has the final tutorial implementation. To follow the instructions, you can create a new oneserver.tsor change the content of the cloned version.

In the example, the server is also implemented in TypeScript and works with Node.js. Since VS Code already ships with the Node.js runtime, you don't need to ship your own version unless you have specific runtime requirements.

The language server source code can be found at/server. Interesting part on the serverpacked.jsonthe file is:

"addiction": { "vscode language server":„^7.0.0”, "vscode-language-server-textdocument":"^1.0.1"}

It's bullshitvscode language serverlibraries.

(Video) Attacking Language Server JSON RPC

Below is a server implementation that uses the included text document manager that synchronizes text documents, always sending incremental differences from the VS code to the server.

import{ make a connection, Text documents, Diagnostic, Diagnostic validity, Suggested features, Initialize the parameters, DidChangeConfigurationNotification, Rounding off the article, Type of completion item, TextDocumentPositionParams, A text document of the synchronization type, Initialize the result}z "vscode-languageserver/čvor";import{text document}z 'vscode-taalserver-textdocument';// Connect to the server using the node's IPC as the transport.// Also includes all preview/proposed LSP functions.allow connection=make a connection(Suggested features.already);// Create a simple text document manager.allow documents:Text documents<text document> =novi Text documents(text document);allow has configuration options:logically=LIE;allow heeftWorkspaceFolderCapability:logically=LIE;allow maDiagnosticRelatedInformationCapability:logically=LIE;connection.click Initialize((parameters:Initialize the parameters)=>{ allow possibilities=parameters.possibilities; // Does the client support the `workspace/configuration` request? // If not, we revert to the global settings. has configuration options= !!( possibilities.field&&!!possibilities.field.configuration); heeftWorkspaceFolderCapability= !!( possibilities.field&&!!possibilities.field.Workspace maps); maDiagnosticRelatedInformationCapability= !!( possibilities.text document&& possibilities.text document.postDiagnose&& possibilities.text document.postDiagnose.related information); art result:Initialize the result= { options:{ tekstDocumentSync: A text document of the synchronization type.Increasing, // Tell the client that this server supports code completion. completion Supplier:{ resolve vendor: WHERE}}}; I(heeftWorkspaceFolderCapability) { result.possibilities.field= { workspace folders:{ maintain: WHERE}};} yield result;});connection.uninitialized(()=>{ I(has configuration options) { // Register for all configuration changes. connection.Client.Register(DidChangeConfigurationNotification.tip,indefinite);} I(heeftWorkspaceFolderCapability) { connection.field.onDidChangeWorkspaceFoldery(_an event =>{ connection.console.log("Received workspace map change event.");});}});// View settingskoppel Example settings{ maxNumberIssues:number;}// General settings used when the `workspace/configuration` request is not supported by the client.// Note that this is not the case when using this server with the client in this example// but this can happen with other clients.art Standard items:Example settings= {maximum number of problems: 1000};allow General settings:Example settings=Standard items;// Settings cache of all open documentsallow document items:Card<series,That is possible<Example settings>> =novi Card();connection.onDidChangeConfiguration(To change =>{ I(has configuration options) { // Clear all cached document settings document items.clear();}Anders{ General settings= <Example settings>((To change.institution.languageServerExample||Standard items));} // Recheck all open text documents documents.already().for everyone(Confirm the text document);});function getDocumentSettings(blush:series):That is possible<Example settings> { I(!has configuration options) { yield Promise.arrange(General settings);} allow result=document items.get(blush); I(!result) { result=connection.field.getConfiguration({ achieves: blush, Section: "languageServerExample"}); document items.set(blush,result);} yield result;}// Keep settings for open documents onlydocuments.detention(mi =>{ document items.delete(mi.document.vas);});// The content of the text document has been changed. This event is being broadcast// when the text document is first opened or its contents changed.documents.opDidChangeContent(To change =>{ Confirm the text document(To change.document);});asynchronous function Confirm the text document(text document:text document):Promise<vacuum> { // In this simple example, we get the settings for each validation run. allow institution=to wait getDocumentSettings(text document.vas); // The validator performs diagnostics for all capitalized words of length 2 and more allow text=text document.downloadText(); allow insert=/\B[A-Z]{2,}\B/G; allow M:RegExpExecArray|nula; allow questions=0; allow diagnostic:Diagnostic[] = []; one second((M=insert.performer(text)) &&questions<institution.maxNumberIssues) { questions++; allow diagnostic:Diagnostic= { Ernst: Diagnostic validity.Warning, reach:{ start: text document.positieAt(M.Content), end: text document.positieAt(M.Content+M[0].lenght)}, message: `${M[0]}is written in capital letters.`, bron: 'were'}; I(maDiagnosticRelatedInformationCapability) { diagnostic.related information= [{ Place:{ Address: text document.vas, reach: Object.assign({},diagnostic.reach)}, message: "Spelling is important"},{ Place:{ Address: text document.vas, reach: Object.assign({},diagnostic.reach)}, message: "Especially for Namur"}];} diagnostic.Press(diagnostic);} // Send the calculated diagnostics to VS Code. connection.send diagnostics({Address: text document.vas,diagnostic});}connection.opDidChangeWatchedFiles(_To change =>{ // Watched files are changed to VS code connection.console.log("We received a file change event");});// This handler returns the initial list of completed items.connection.already((_textDocumentPosition:TextDocumentPositionParams):Rounding off the article[]=>{ // The pass parameter contains the position of the text document w // which code is complete as requested. For example, we ignore it // info and always have the same additional items. yield[{ ticket: 'Typscript', Decent: Type of completion item.Text, deen: 1},{ ticket: „JavaScript”, Decent: Type of completion item.Text, deen: 2}];});// This handler resolves additional information for the selected item// completion list.connection.onCompletionResolve((article:Rounding off the article):Rounding off the article =>{ I(article.deen===1) { article.Detail="TypeScript Details"; article.documentation="TypeScript Documentation";}Anders I(article.deen===2) { article.Detail="JavaScript-Details"; article.documentation="JavaScript Documentation";} yield article;});// Make the text document manager listen for a connection// for opening, modifying and closing text documentsdocuments.Listen(connection);// Listen onlineconnection.Listen();

Add simple validation

To add document validation to the server, we add a listener to the text document manager that is called when the content of the text document changes. The server then decides when it is best to validate the document. In the example implementation, the server validates the plain text document and selects all words that use CAPITAL LETTERS. The relevant code snippet looks like this:

// The content of the text document has been changed. This event is being broadcast// when the text document is first opened or its contents changed.documents.opDidChangeContent(asynchronous To change =>{ allow text document=To change.document; // In this simple example, we get the settings for each validation run. allow institution=to wait getDocumentSettings(text document.vas); // The validator performs diagnostics for all capitalized words of length 2 and more allow text=text document.downloadText(); allow insert=/\B[A-Z]{2,}\B/G; allow M:RegExpExecArray|nula; allow questions=0; allow diagnostic:Diagnostic[] = []; one second((M=insert.performer(text)) &&questions<institution.maxNumberIssues) { questions++; allow diagnostic:Diagnostic= { Ernst: Diagnostic validity.Warning, reach:{ start: text document.positieAt(M.Content), end: text document.positieAt(M.Content+M[0].lenght)}, message: `${M[0]}is written in capital letters.`, bron: 'were'}; I(maDiagnosticRelatedInformationCapability) { diagnostic.related information= [{ Place:{ Address: text document.vas, reach: Object.assign({},diagnostic.reach)}, message: "Spelling is important"},{ Place:{ Address: text document.vas, reach: Object.assign({},diagnostic.reach)}, message: "Especially for Namur"}];} diagnostic.Press(diagnostic);} // Send the calculated diagnostics to VS Code. connection.send diagnostics({Address: text document.vas,diagnostic});});

Diagnostic tips and tricks

  • If the start and end positions are the same, VS Code will underline the word at that position.
  • To wrap the underscore to the end of the line, set the end position character to Number.MAX_VALUE.

Follow these steps to start the language server:

  • Press⇧⌘B(Windows, LinuxCtrl+Shift+B)to start construction. The job builds both the client and the server.
  • openStartview, selectionStart the clientrun the setting and pressStart debuggingbutton to perform additionalExtension development hostinstance of VS code that executes the extension code.
  • to createtest.txtfile in the root folder and paste the following content:
TypeScript lets you write JavaScript the way you want. TypeScript is a typed superset of JavaScript that can be translated into plain JavaScript. ANY browser. ANY host. ANY operating system. open source.

FromExtension development hostthe instance will then look like this:

Language Server Extensions Handbook (3)

Debugging both client and server

Debugging client code is as easy as debugging a regular extension. Set a breakpoint in the client code and debug the extension by pressingF5.

Language Server Extensions Handbook (4)

Since the server leadsLanguageClientrunning in the extension (client), we need to attach the debugger to the running server. Go to for thisRun and debugview and select a startup configurationJoin the serverand pressF5. This will connect the debugger to the server.

Language Server Extensions Handbook (5)

Language server login support

If you usevscode-taalclientfor a client implementation, you can specify a setting[langId].tracking.serverwhich directs the client to record language client/server communication on the language client channelTo do.

Forlsp example, you can set this setting:"languageServerExample.trace.server": "pełny". Now go to the "Language Server Example" channel. You should see the logs:

Language Server Extensions Handbook (6)

Use the configuration settings on the server

When writing the client part of the extension, we already defined a setting that controls the highest number of reported problems. We also wrote server-side code to read these settings from the client:

function getDocumentSettings(blush:series):That is possible<Example settings> { I(!has configuration options) { yield Promise.arrange(General settings);} allow result=document items.get(blush); I(!result) { result=connection.field.getConfiguration({ achieves: blush, Section: "languageServerExample"}); document items.set(blush,result);} yield result;}

All we need to do now is listen for server-side configuration changes and, if the setting changes, reauthenticate the open text documents. To reuse the validation logic to handle the document change event, we extract the code to a fileConfirm the text documentfunction and change the code to amaxNumberIssueschangeable:

asynchronous function Confirm the text document(text document:text document):Promise<vacuum> { // In this simple example, we get the settings for each validation run. allow institution=to wait getDocumentSettings(text document.vas); // The validator performs diagnostics for all capitalized words of length 2 and more allow text=text document.downloadText(); allow insert=/\B[A-Z]{2,}\B/G; allow M:RegExpExecArray|nula; allow questions=0; allow diagnostic:Diagnostic[] = []; one second((M=insert.performer(text)) &&questions<institution.maxNumberIssues) { questions++; allow diagnostic:Diagnostic= { Ernst: Diagnostic validity.Warning, reach:{ start: text document.positieAt(M.Content), end: text document.positieAt(M.Content+M[0].lenght)}, message: `${M[0]}is written in capital letters.`, bron: 'were'}; I(maDiagnosticRelatedInformationCapability) { diagnostic.related information= [{ Place:{ Address: text document.vas, reach: Object.assign({},diagnostic.reach)}, message: "Spelling is important"},{ Place:{ Address: text document.vas, reach: Object.assign({},diagnostic.reach)}, message: "Especially for Namur"}];} diagnostic.Press(diagnostic);} // Send the calculated diagnostics to VS Code. connection.send diagnostics({Address: text document.vas,diagnostic});}

Configuration change handling is done by adding a configuration change notification handler to the connection. The relevant code looks like this:

connection.onDidChangeConfiguration(To change =>{ I(has configuration options) { // Clear all cached document settings document items.clear();}Anders{ General settings= <Example settings>((To change.institution.languageServerExample||Standard items));} // Recheck all open text documents documents.already().for everyone(Confirm the text document);});

Restarting the client and changing the setting to maximum report 1 problem results in the following check:

(Video) Create Custom Syntax Highlighting in VS Code | Programming Language | Software Coding Tutorials

Language Server Extensions Handbook (7)

Add additional language features

The first interesting feature that a language server usually implements is document validation. In this sense, even a linter counts as a language server, and in VS Code linters are usually implemented as language servers (seeeslintandjshintfor example). But language servers are more than that. They can enable code completion, find all references, or jump to definitions. The following code example adds code completion to the server. It suggests two words "TypeScript" and "JavaScript".

// This handler returns the initial list of completed items.connection.already((_textDocumentPosition:TextDocumentPositionParams):Rounding off the article[]=>{ // The pass parameter contains the position of the text document w // which code is complete as requested. For example, we ignore it // info and always have the same additional items. yield[{ ticket: 'Typscript', Decent: Type of completion item.Text, deen: 1},{ ticket: „JavaScript”, Decent: Type of completion item.Text, deen: 2}];});// This handler resolves additional information for the selected item// completion list.connection.onCompletionResolve((article:Rounding off the article):Rounding off the article =>{ I(article.deen===1) { article.Detail="TypeScript Details"; article.documentation="TypeScript Documentation";}Anders I(article.deen===2) { article.Detail="JavaScript-Details"; article.documentation="JavaScript Documentation";} yield article;});

Fromdeenfields are used to uniquely identify the completion element in the solution handler. The data property is transparent to the protocol. Since the underlying messaging protocol is based on JSON, the data field should only contain data that can be serialized to and from JSON.

The only thing missing is telling VS Code that the server is handling code completion requests. To do this, check the corresponding option in the initialization handler:

connection.click Initialize((parameters):Initialize the result =>{... yield{ options:{... // Tell the client that the server supports code completion termination provider: { resolve vendor: WHERE}}};});

The screenshot below shows the finished code running in a plain text file:

Language Server Extensions Handbook (8)

Language server testing

To create a high-quality language server, we need to build a proper test suite that covers its features. There are two common ways to test language servers:

  • Unit Test: This is useful if you want to test certain features on the language servers by simulating all the information being sent to them. VS codesHTML/CSS/JSONLanguage servers use this approach to testing. The npm LSP modules also use this approach. SeeHerefor some unit tests written using the npm protocol module.
  • Extensive test: It is similarVS Code Extensie Test. The advantage of this approach is that the test is run by creating an instance of VS Code with a workspace, opening the file, activating the language client/server, andVS code commands. This approach is better if you have files, settings, or dependencies (such asnode_modules) which is difficult or impossible to mock. PopularPythonextension follows this testing approach.

It is possible to run a unit test in any testing framework of your choice. Here we describe how to perform extensive testing of language server extensions.

open.vscode/launch.json, and can be foundE2Eexam objective:

{ "to do":"E2E server language test", "tip":"host extension", "Application":"start", "executable file":"${execPath}", "arguments": [ "--extensionDevelopmentPath=${workspaceRoot}", "--extensionTestsPath=${workspaceRoot}/client/out/test/index", "${workspaceRoot}/client/testFixture"], "output files": ["${workspaceRoot}/client/out/test/**/*.js"]}

Running this debug target will launch an instance of VS Code fromclient/test deviceas an active workspace. VS Code will then continue to run all testsclient/source/test. As a debugging tip, you can set breakpoints in typescript filesclient/source/testand they will be affected.

Let's seecompletion.test.tsduration:

import * How everywhere, everywhere z „vscode”;import * How under condition z 'under condition';import{download DocUri,Activate}z './aide';set("need to finish", ()=>{ art a horse=download DocUri("completed.txt"); test("JS/TS ends in txt file",asynchronous()=>{ to wait End of trial(a horse,novi everywhere, everywhere.Position(0,0), { things:[{ticket: „JavaScript”,Decent: everywhere, everywhere.Type of completion item.Text},{ticket: 'Typscript',Decent: everywhere, everywhere.Type of completion item.Text}]});});});asynchronous function End of trial( a horse:everywhere, everywhere.Uri, position:everywhere, everywhere.Position, list of expected completion:everywhere, everywhere.Completion list) { to wait Activate(a horse); // Run `vscode.executeCompletionItemProvider` to simulate trigger completion art the actual list of endings= (to wait everywhere, everywhere.commandos.execute the command( "vscode.executeCompletionItemProvider", a horse, position))How everywhere, everywhere.Completion list; under condition.Alright(the actual list of endings.things.lenght>=2); list of expected completion.things.for everyone((expected item,and)=>{ art Actually=the actual list of endings.things[and]; under condition.equivalent(Actually.ticket,expected item.ticket); under condition.equivalent(Actually.Decent,expected item.Decent);});}

In this test:

  • Activate the extension.
  • Run the commandvscode.executeCompletionItemProviderwith the URI and position to simulate the interrupt trigger.
  • Confirm returned shipping items with our expected shipping items.

Let's dive a little deeper into itactivation (docURI)function. It is stated inclient/source/test/helper.ts:

import * How everywhere, everywhere z „vscode”;import * How pad z 'substrate';export allow of art:everywhere, everywhere.text document;export allow editor:everywhere, everywhere.text editor;export allow documentEol:series;export allow platformaEol:series;/*** Activates the vscode.lsp sample extension*/export asynchronous function Activate(a horse:everywhere, everywhere.Uri) { // Extension ID is `name.publisher` from package.json file art int=everywhere, everywhere.extensions.download the extension('vscode-examples.lsp-przyklad')!; to wait int.Activate(); to attempt{ of art=to wait everywhere, everywhere.field.open a text document(a horse); editor=to wait everywhere, everywhere.window.display text document(of art); to wait sleep(in 2000);// Wait for server activation}to catch(mi) { console.wrong(mi);}}asynchronous function sleep(SM:number) { yield novi Promise(arrange => Set a time limit(arrange,SM));}

In the activation section:

  • Download the extension from{publisher.name}.{extensionId}as stated inpacked.json.
  • Open the specified document and display it in the active text editor.
  • Idle for 2 seconds to make sure the language server is created.

When we are ready, we can runVS code commandscorresponding to each language function and validate the returned result.

There is another test that contains a diagnostic function that has just been implemented. Check out atclient/source/test/diagnostics.test.ts.

(Video) #Backend, David Driscoll, If I can make a Language Server, so can you!

Advanced themes

So far this guide covers:

  • A brief overview of the language server and the language server protocol.
  • Language Server Extension Architecture in VS Code
  • Fromlsp exampleextension and how to develop/debug/verify/test it.

There are some more advanced topics that we couldn't fit into this guide. We will include links to these resources for further study of language server development.

Additional language server functions

The following language features are currently supported on the language server with code completion:

  • Main features of the document: Highlights all "equals" symbols in a text document.
  • Conduct: Provides information about hovering over the selected symbol in a text document.
  • signature help: Provides subtitle help for the symbol selected in the text document.
  • Definition: takes you to the definition of the selected symbol in the text document.
  • Go to type definition: jumps to the type/interface definition for the selected symbol in the text document.
  • Go to implementation: Allows you to switch to implementation definition support for the selected symbol in the text document.
  • Find references: Finds all project-wide references for the selected symbol in the text document.
  • List of document symbols: Contains a list of all symbols defined in the text document.
  • List the workspace symbols: Lists all symbols in the entire project.
  • Code actions: calculates the commands to be performed (usually beautification/refactoring) for the given text document and range.
  • CodeLens: Calculates CodeLens statistics for the given text document.
  • Formatting of documents: This includes formatting entire documents, ranges of documents, and formatting by type.
  • Rename: rename the symbol through the project.
  • Links to documents: Calculate and resolve links in a document.
  • Colors of documents: Calculate and resolve the colors in the document to enable color selection in the editor.

FromFeatures of the programming languagetopic describes each of the above language features and provides guidance on how to implement them through the language server protocol or using the extensibility API directly from your extension.

Incremental synchronization of text documents

The example uses a simple text document manager provided by the packagevscode language servera module for synchronizing documents between VS Code and the language server.

This has two drawbacks:

  • A lot of data is transferred because the entire content of the text document is repeatedly sent to the server.
  • If an existing language library is used, such libraries typically support incremental document updates to avoid unnecessary parsing and syntax tree abstraction.

Therefore, the protocol also supports incremental document synchronization.

To take advantage of incremental document synchronization, the server must install three notification handlers:

  • opDidOpenTextDocument: called when a text document is opened in VS Code.
  • opDidChangeTextDocument: called when the content of a text document is changed in VS code.
  • onDidCloseTextDocument: called when a text document is closed in VS code.

Below is a code snippet that illustrates how to bind these notification handlers to a connection and return the correct capability during initialization:

connection.click Initialize((parameters):Initialize the result =>{... yield{ options:{ // Enable incremental document synchronization tekstDocumentSync: A text document of the synchronization type.Increasing,...}};});connection.opDidOpenTextDocument((parameters)=>{ // A text document is opened in VS Code. // params.uri uniquely identifies the document. For documents stored on disk, this is the URI of the file. // params.text initial full text of the document.});connection.opDidChangeTextDocument((parameters)=>{ // The content of the text document has been changed to VS code. // params.uri uniquely identifies the document. // params.contentChanges describes changes in the content of the document.});connection.onDidCloseTextDocument((parameters)=>{ // Text document is closed in VS code. // params.uri uniquely identifies the document.});/*Make the text document manager listen for the connectionfor opening, changing and closing text documents.Comment out this line to enable `connection.onDidOpenTextDocument`,`connection.onDidChangeTextDocument` and `connection.onDidCloseTextDocument` for event handling*/// documents.listen(connection);

Use the VS Code API directly to implement language features

Although language servers have many advantages, they are not the only option for extending the editing capabilities of VS Code. In cases where you want to add some simple language features for a document type, consider usingvscode.languages.register[LANGUAGE_FEATURE]Dostavaas an option.

here it isexample of restorationdoorvscode.languages.registerCompletionItemProviderto add some snippets to plain text files.

More examples illustrating the use of the VS Code API can be found athttps://github.com/microsoft/vscode-extension-samples.

An error-tolerant language server parser

In most cases, the code in the editor is incomplete and syntactically incorrect, but developers still expect auto-completion and other language features to work. Therefore, the language server needs an error-tolerant parser: the parser generates meaningful ASTs from partially complete code, and the language server provides language functions based on the AST.

As we've been improving PHP support in VS Code, we've realized that the official PHP parser is not error-proof and cannot be reused directly on the language server. That's why we kept workingMicrosoft/tolerante-php-parserand on the left in detailnoteswhich can help language server authors who need to implement a fault-tolerant parser.

Frequently asked questions

When I try to connect to the server I get the message "unable to connect during runtime (timeout after 5000ms)"?

You will get this timeout error if the server is down when you try to mount the debugger. The client runs the language server, so make sure you run the client to have a running server. You may also need to disable client breakpoints if they interfere with starting the server.

I have read this manual andLSP specificationbut I still have unsolved questions. Where can I get help?

Please open an issuehttps://github.com/microsoft/language-server-protocol.

(Video) 2022/03/28 CWScript VSCode Extension + LSP tutorial

5.03.2023

FAQs

What language are VS Code extensions written in? ›

VS Code extensions support two main languages: JavaScript and TypeScript.

Does VS Code use LSP? ›

The HTML Language Client and PHP Language Client are normal VS Code extensions written in TypeScript. Each of them instantiates a corresponding Language Server and communicates with them through LSP.

How do LSPS work? ›

LSP Message Types
  1. The client opens the file and sends textDocument/didOpen to the server.
  2. The server analyzes the file and sends the textDocument/publishDiagnostics notification.
  3. The client parses the results and displays error indicators in the editor.

What is LSP used for? ›

The language server protocol (LSP) is the product of standardizing the messages exchanged between a development tool and a language server process. Using language servers or demons is not a new or novel idea. Editors like Vim and Emacs have been doing this for some time to provide semantic auto-completion support.

Can you write VS Code extensions in Python? ›

The Python extension template helps get you started building a Visual Studio Code extension for your favorite Python tool. It could be a linter, formatter, or code analysis, or all of those together.

What are extensions coded in? ›

Chrome extensions are built with HTML, JavaScript, and CSS scripts and are essentially small websites uploaded to the Chrome store. The only difference between a Chrome extension and a regular website is that extensions contain a manifest file, which gives them a specific function to execute.

Does VS Code support Delphi? ›

Delphi Extension Pack is an open source extension created for Visual Studio Code.

Can VS Code run all programming languages? ›

In Visual Studio Code, we have support for almost every major programming language. Several ship in the box, for example, JavaScript, TypeScript, CSS, and HTML but more rich language extensions can be found in the VS Code Marketplace.

What is GLSL in VS Code? ›

vscode-glsl is a light weighted GLSL (OpenGL Shading Language) syntax highlighting extension for Visual Studio Code.

Did Microsoft invent LSP? ›

Language Server Protocol or LSP is a communication standard originally created by Microsoft with the objective of defining a better protocol between a source code editor or the IDE implemented by the developer and the servers that contain all the specifications and functions of a specific programming language.

What is Delphi LSP? ›

DelphiLSP.exe is a Delphi language server implementing the Language Server Protocol (LSP). It encapsulates language features such as code completion and error insight. It's used within the IDE, but can also be used with Visual Studio Code or other editors that support the LSP protocol.

How is an LSP created? ›

LSP is created in two ways in IP/MPLS over MPLS-TP. One way is to create MPLS-TP LSP, and notify the IP/MPLS network in FA (forwarding adjacent) mode. When IP/MPLS LSP is created, the created TP LSP can be considered as a direct link to participate in the routing.

What are the two types of LSP? ›

There are two signaled LSP types:
  • Explicit-path LSPs — MPLS uses RSVP-TE to set up explicit path LSPs. The hops within the LSP are configured manually. ...
  • Constrained-path LSPs — The intermediate hops of the LSP are dynamically assigned.

What is the advantage of LSP? ›

If your code adheres to the Liskov Substitution Principle you have many benefits. These include: code re-usability, reduced coupling, and easier maintenance.

What is an LSP code? ›

The LSP code, a software product of Voss Scientific Corporation, is an advanced 3D electromagnetic particle-in-cell (PIC) code designed for complex, large-scale plasma simulations on parallel and serial platforms; the numerical code supports Cartesian, cylindrical, and spherical coordinate systems and can also be used ...

Is VS Code is best for Python? ›

VS Code comes with great debugging support for Python, allowing you to set breakpoints, inspect variables, and use the debug console for an in-depth look at how your program is executing step by step. Debug a number of different types of Python applications, including multi-threaded, web, and remote applications.

Can we practice Python in VS Code? ›

Visual Studio Code is a free source code editor that fully supports Python and useful features such as real-time collaboration. It's highly customizable to support your classroom the way you like to teach.

What 2 is the extension for Python? ›

The extensions for Python files are - . py, . pyi, . pyc, .

What are the top 10 VS Code extension? ›

Therefore I created this list containing the 10 best VS Code extensions for JavaScript including JavaScript (ES6) code snippets, EsLint, DotEnv, JavaScript booster, Prettier, Tailwind CSS IntelliSense, Sort lines, Git Lens, Git Graph, and GitHub Copilot.

Do VS Code support SQL? ›

Visual Studio Code is a graphical code editor for Linux, macOS, and Windows. It supports extensions, including the mssql extension for querying a SQL Server instance, Azure SQL Database, an Azure SQL Managed Instance, and a database in Azure Synapse Analytics.

Is Delphi better than C++? ›

Delphi Is Fast

This allows the software to utilize multiple memory allocations in a way alternative languages like C or C++ cannot. Similarly, Delphi can use strings faster than C and C++. However, the main thing to note about Delphi isn't just its speed, but its parity.

Does VS Code have its own compiler? ›

VS Code is now configured to use the Microsoft C++ compiler. The configuration applies to the current workspace. To reuse the configuration, just copy the JSON files to a .vscode folder in a new project folder (workspace) and change the names of the source file(s) and executable as needed.

What is the difference between VS Code and Visual Studio Code? ›

VS Code has built-in support for Node. js, TypeScript, and JavaScript and a feature-rich extension ecosystem for different languages like C++, Java, C#, PHP, Go, and Python. Visual Studio Code falls in the same category as Atom, Sublime, and Text Wrangler, but with better and more robust features.

What is the most popular language on VS Code? ›

Python is the most popular programming language used in VS Code, if gauged by downloads of the top language extensions, which provide language "smartness" in the popular open source, cross-platform code editor.

What coding language does Microsoft use? ›

C++: C++ is the workhorse language at Microsoft, which uses C++ to build many of its core applications. C++ is used to create computer programs and is one of the most used languages in game development. It's the core language in many operating systems, browsers, and games.

Should I learn HLSL or GLSL? ›

High-Level Shading Language (HLSL) is arguably the best language for writing shaders, as it's very well supported, separates samplers and textures (unlike GLSL), and has common language features like: namespaces. template generics. overloadable operators.

Is Lua in Visual Studio Code? ›

lua-language-server. The Lua language server provides various language features for Lua to make development easier and faster. With around half a million installs on Visual Studio Code, it is the most popular extension for Lua language support.

Does Unreal use HLSL or GLSL? ›

Unreal will generate HLSL for any nodes that contribute to the final output. In this case, Unreal will generate HLSL for the SceneTexture node. To view the HLSL code for the entire material, select Window\HLSL Code. This will open a separate window with the generated code.

What program did Bill Gates use to make Microsoft? ›

But here's what Gates did: he bought a program from a small software company called the Quick and Dirty Operating System (or Q-DOS), for the price of 75,000$. Q-DOS was, in fact, a ripoff of Gary's CPM program. He then changed its name to MS-DOS (Microsoft DOS) and licensed it to IBM.

What did Bill Gates use to create Microsoft? ›

In 1975 Gates, then a sophomore at Harvard University, joined his hometown friend Paul G. Allen to develop software for the first microcomputers. They began by adapting BASIC, a popular programming language used on large computers, for use on microcomputers.

What is the oldest Microsoft program? ›

Core apps and services

The first version of Word, released in the autumn of 1983, was for the MS-DOS operating system and introduced the computer mouse to more users. Word 1.0 could be purchased with a bundled mouse, though none was required.

Is Delphi a dead programming language? ›

The story of this language is pretty simple and tragic. Pascal (the programming language) led to the creation of Delphi. Delphi soon took the place of Pascal, condemning it to the list of dead programming languages.

Does Delphi use C++? ›

Writing C++-friendly Delphi Code. C++ can consume Delphi code. The Delphi command-line compiler uses the following switches to generate the files that C++ needs to process Delphi code: The -JL switch generates .

Is Delphi a compiler or interpreter? ›

Both C++ and Delphi are non-interpreted. They are compiled, native programming languages based on old-school approaches.

What is LSP in Python? ›

Language Server Protocol is a JSON-RPC protocol that allows text editors and IDEs to delegate language-aware features (such as autocomplete, or jump-to-definition) to a common server process.

What is the difference between LSP and tunnel? ›

Tunnel: what you configure in the router, it is keyword used by Cisco to indicate the interface. For ex: I will configure a tunnel between Router1 and Router2. LSP: is somehow virtual, means if you combine the labels between R1 and R2 and put them in top of each other. You will get an LSP.

Who developed LSP? ›

History. LSP was originally developed for Microsoft Visual Studio Code and is now an open standard. On June 27, 2016, Microsoft announced a collaboration with Red Hat and Codenvy to standardize the protocol's specification. The protocol is supported and has been adopted by the three companies.

What is the difference between LSA and LSP? ›

What is an LSA and LSP? An LSA is a Learning Support Assistant and an LSP is Learning Support Practitioner. This is somebody who supports learning in the classroom. Sometimes they will support individual children, at other times they may work with a group or with the whole class.

Is LSP bidirectional? ›

Because RSVP LSPs are unidirectional, a routed return path is used for the BFD control packets from the egress LER toward the ingress LER.

What does LSP contain? ›

Link State Packet (LSP) is a packet of information generated by a network router in a link state routing protocol that lists the router's neighbors. Link state packets can be further defined as special datagrams that determine the names of and the cost or distance to any neighboring routers and associated networks.

What is the difference between LSP and isp? ›

The LSP governs relationships between parent and child classes (i.e. hierarchical relationships). It tells you how to implement an API. The ISP governs relationships between parent and client classes (i.e. producer/consumer relationships). It tells you when to implement an API.

How do I choose an LSP? ›

Choosing the right LSP: What you really need to know
  1. Understand your key drivers. You can't spot the right match if you don't know what you're looking for, so having a clear idea of your needs and why you need support is essential. ...
  2. Identify the services you need. ...
  3. Evaluate the quote. ...
  4. Consider specialist knowledge and tools.
Mar 29, 2022

What is an example of a LSP violation? ›

For instance, if you have a foreach loop over a collection of objects of type Foo, and within this loop there is a check to see if Foo is in fact Bar (subtype of Foo), then this is almost certainly an LSP violation.

How do I enable LSP server? ›

To globally enable a server, open the Command Palette and choose "LSP: Enable Language Server Globally". This will add "enabled": true to the corresponding language server setting under the "clients" key in your user-settings file for LSP. Your user-settings file is stored at Packages/User/LSP.

What are the capabilities of LSP client server? ›

LSP facilitates features like go-to-definition, find-references, hover, completion, rename, format, refactor, etc., using semantic whole-project analysis (unlike ctags).

Which language is used in VS Code? ›

Learn about programming languages supported by VS Code. These include: C++ - C# - CSS - Dart - Dockerfile - F# - Go - HTML - Java - JavaScript - JSON - Julia - Less - Markdown - PHP - PowerShell - Python - R - Ruby - Rust - SCSS - T-SQL - TypeScript.

What language does visual code use? ›

JavaScript is a first-class language in Visual Studio. You can use most or all of the standard editing aids (code snippets, IntelliSense, and so on) when you write JavaScript code in the Visual Studio IDE.

Is VS Code written in electron? ›

Electron is the main framework that enables VS Code for desktop to run on all our supported platforms (Windows, macOS, and Linux). It combines Chromium with browser APIs, the V8 JavaScript engine, and Node.

Is VS Code written in HTML? ›

HTML in Visual Studio Code. Visual Studio Code provides basic support for HTML programming out of the box. There is syntax highlighting, smart completions with IntelliSense, and customizable formatting. VS Code also includes great Emmet support.

Is VS Code a Python interpreter? ›

Note: By default, VS Code uses the interpreter selected for your workspace when debugging code. You can override this behavior by specifying a different path in the python property of a debug configuration. See Choose a debugging environment.

Is VS Code an IDE or compiler? ›

Visual Studio is the fastest IDE for productivity. Target any platform, any device. Build any type of application. Work together in real time.

What is better than VS Code? ›

Atom, Visual Studio, Eclipse, IntelliJ IDEA, and WebStorm are the most popular alternatives and competitors to Visual Studio Code. Everyone errors. Make sure your application doesn't. Everyone errors.

Is VS Code written in TypeScript? ›

Visual Studio Code is a cross platform code editor written in TypeScript based on Code OSS with support for extensions and a wide range of programming languages.

What is the VS Code framework? ›

Visual Studio Code, also commonly referred to as VS Code, is a source-code editor made by Microsoft with the Electron Framework, for Windows, Linux and macOS. Features include support for debugging, syntax highlighting, intelligent code completion, snippets, code refactoring, and embedded Git.

What are the disadvantages of Visual Studio Code? ›

Cons: Some workflows are not very intuitive, and need to be executed using the Command Palette. If you are migrating from another IDE like Eclipse or NetBeans, this will take some time to get used to. For example, to create a Java project, you need to open the Command Palette and type "Java: Create Java Project".

Can I write R in VS Code? ›

The R extension for Visual Studio Code supports extended syntax highlighting, code completion, linting, formatting, interacting with R terminals, viewing data, plots, workspace variables, help pages, managing packages and working with R Markdown documents.

Is VS Code good for Python? ›

VS Code comes with great debugging support for Python, allowing you to set breakpoints, inspect variables, and use the debug console for an in-depth look at how your program is executing step by step. Debug a number of different types of Python applications, including multi-threaded, web, and remote applications.

Is VS Code used in industry? ›

We have data on 18,229 companies that use Visual Studio Code. The companies using Visual Studio Code are most often found in United States and in the Information Technology and Services industry. Visual Studio Code is most often used by companies with 50-200 employees and 1M-10M dollars in revenue.

What is the difference between Visual Studio and Visual Studio Code? ›

Visual Studio is an Integrated Development Environment, also known as an IDE. Visual Studio Code is a code editor. A developer can easily edit their code. VS is slower when it comes to performing across different platforms.

Who owns Visual Studio Code? ›

MICROSOFT VISUAL STUDIO CODE. These license terms are an agreement between you and Microsoft Corporation (or based on where you live, one of its affiliates).

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