@shopify/theme-language-server-common NPM

The Language Server Protocol empowers developers to provide code editing features to all code editors in a single code base with no code-editor-specific code.

This module serves as a runtime-agnostic Liquid Language Server so that we can also run it inside the Online Store Code Editor (via a CodeMirror Language Client).

You may be interested in the sibling modules:

@shopify/theme-language-server-common — (you are here) Runtime agnostic Language Server that can run in browser or Node.js.
@shopify/theme-language-server-browser — Browser specific wrapper over the common library.
@shopify/theme-language-server-node — Node.js specific wrapper over the common library.

Usage

This repo only contains the library over the functionality. The CLI is implemented in Shopify/cli.

Node

The Node.js version comes with batteries included and uses STDIN and STDOUT as the communication channel.

// slim-cli.ts
import { startServer } from '@shopify/theme-language-server-node';

// start the server (batteries included)
startServer();

Browser

The browser version accepts a Web Worker as argument.

// worker.ts
import { startServer, Dependencies } from '@shopify/theme-language-server-browser';

// Provide implementations for the dependency injections
const dependencies: Dependencies = { /* ... */ };

// In a Web Worker, the self object refers to the worker.
startServer(self as any as Worker, dependencies);

Learn more

Read the Language Server Protocol Spec
It's important to understand the following concepts:
- Language Client
- Language Server
- Messages
  - Requests / Response
  - Notifications
  - Message direction
- Client Capabilities
- Server Capabilities
- TextDocument synchronization
- Lifecycle methods
Take a look at the vscode-languageserver-* libraries offered by VS Code.
They have vscode in their name, but only vscode-languageclient is VS Code specific, the other libraries can be used in non-VS Code contexts (we do this here).
- vscode-languageserver-server
  This library provides the connection object and is runtime agnostic. The entire spec is implemented and thus you can hook into every message type.
  Examples: connection.onInitialize(params => {}), connection.onTextDocumentDidOpen(params => {}), etc.
- vscode-languageserver-protocol
  This library is useful to reuse and type check message parameter types.
  Examples: PublishDiagnosticsNotification, DiagnosticClientCapabilities, DiagnosticServerCapabilities, etc.
- vscode-languageserver-types
  This library is useful to get the types of specific parts of the Protocol.
  Examples: Diagnostic, URI, TextDocument, Position, Range, LocationLink, etc.