自分で作る VS Code 拡張と Language Server — 2026 年 LSP 実戦ガイド

{
  "name": "todo-highlighter",
  "displayName": "TODO Highlighter",
  "version": "0.1.0",
  "publisher": "yj",
  "engines": { "vscode": "^1.95.0" },
  "main": "./out/extension.js",
  "activationEvents": ["onStartupFinished"],
  "categories": ["Other"],
  "contributes": {
    "commands": [
      {
        "command": "todoHighlighter.scanWorkspace",
        "title": "TODO: Scan Workspace"
      }
    ],
    "configuration": {
      "title": "TODO Highlighter",
      "properties": {
        "todoHighlighter.keywords": {
          "type": "array",
          "default": ["TODO", "FIXME", "HACK"],
          "description": "Keywords to highlight"
        }
      }
    }
  }
}

"activationEvents": [
  "onLanguage:tomlplus",
  "onCommand:tomlplus.format",
  "workspaceContains:**/.tomlplus"
]

import * as vscode from 'vscode';

export function activate(context: vscode.ExtensionContext) {
  console.log('TODO Highlighter activated');

  const disposable = vscode.commands.registerCommand(
    'todoHighlighter.scanWorkspace',
    async () => {
      const files = await vscode.workspace.findFiles('**/*.{ts,js,md}', '**/node_modules/**');
      vscode.window.showInformationMessage(`Scanned ${files.length} files`);
    }
  );

  context.subscriptions.push(disposable);
}

export function deactivate() {}

const todoDecoration = vscode.window.createTextEditorDecorationType({
  backgroundColor: 'rgba(255, 200, 0, 0.2)',
  border: '1px dashed orange',
  overviewRulerColor: 'orange',
  overviewRulerLane: vscode.OverviewRulerLane.Right,
});

function updateDecorations(editor: vscode.TextEditor) {
  const text = editor.document.getText();
  const regex = /\b(TODO|FIXME|HACK)\b/g;
  const ranges: vscode.Range[] = [];

  let match: RegExpExecArray | null;
  while ((match = regex.exec(text)) !== null) {
    const start = editor.document.positionAt(match.index);
    const end = editor.document.positionAt(match.index + match[0].length);
    ranges.push(new vscode.Range(start, end));
  }
  editor.setDecorations(todoDecoration, ranges);
}

vscode.window.onDidChangeActiveTextEditor(
  (editor) => editor && updateDecorations(editor),
  null,
  context.subscriptions
);

vscode.workspace.onDidChangeTextDocument(
  (event) => {
    const editor = vscode.window.activeTextEditor;
    if (editor && event.document === editor.document) updateDecorations(editor);
  },
  null,
  context.subscriptions
);

Content-Length: 152\r\n
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{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"processId":12345,...}}

client ──▶ initialize ──▶ server
client ◀── initialize result ─ server
client ──▶ initialized ──▶ (notification)
... (通常稼働) ...
client ──▶ shutdown ──▶ server
client ──▶ exit ──▶ server

[server]
host: string = "localhost"
port: int = 8080

[client]
target = $server.host
timeout: int = 30

tomlplus-lsp/
  client/
    src/extension.ts        # VS Code 拡張 (クライアント)
    package.json
  server/
    src/server.ts            # LSP サーバ (Node として実行)
    package.json
  package.json               # ワークスペースルート

import {
  createConnection,
  TextDocuments,
  ProposedFeatures,
  InitializeParams,
  TextDocumentSyncKind,
  InitializeResult,
} from 'vscode-languageserver/node';
import { TextDocument } from 'vscode-languageserver-textdocument';

const connection = createConnection(ProposedFeatures.all);
const documents = new TextDocuments(TextDocument);

connection.onInitialize((params: InitializeParams): InitializeResult => {
  return {
    capabilities: {
      textDocumentSync: TextDocumentSyncKind.Incremental,
      completionProvider: { triggerCharacters: ['.', '$'] },
      hoverProvider: true,
      definitionProvider: true,
      referencesProvider: true,
      renameProvider: { prepareProvider: true },
      codeActionProvider: true,
      documentFormattingProvider: true,
      semanticTokensProvider: {
        legend: {
          tokenTypes: ['keyword', 'string', 'number', 'variable', 'property'],
          tokenModifiers: ['declaration', 'readonly'],
        },
        range: false,
        full: true,
      },
    },
  };
});

documents.listen(connection);
connection.listen();

interface TomlPlusKey {
  section: string;
  key: string;
  type: string | null;
  value: string;
  line: number;
  range: { start: number; end: number };
}

function parse(text: string): { keys: TomlPlusKey[]; errors: ParseError[] } {
  const lines = text.split('\n');
  const keys: TomlPlusKey[] = [];
  const errors: ParseError[] = [];
  let section = '';

  for (let i = 0; i < lines.length; i++) {
    const line = lines[i].replace(/#.*$/, '').trim();
    if (!line) continue;

    const sectionMatch = /^\[([a-zA-Z_][\w]*)\]$/.exec(line);
    if (sectionMatch) { section = sectionMatch[1]; continue; }

    const kvMatch = /^([a-zA-Z_][\w]*)\s*(?::\s*(int|string|bool))?\s*=\s*(.+)$/.exec(line);
    if (!kvMatch) {
      errors.push({ line: i, message: `Invalid syntax: "${line}"` });
      continue;
    }
    keys.push({
      section,
      key: kvMatch[1],
      type: kvMatch[2] ?? null,
      value: kvMatch[3],
      line: i,
      range: { start: 0, end: lines[i].length },
    });
  }
  return { keys, errors };
}

import { Diagnostic, DiagnosticSeverity } from 'vscode-languageserver/node';

documents.onDidChangeContent((change) => {
  validateDocument(change.document);
});

function validateDocument(doc: TextDocument) {
  const text = doc.getText();
  const { keys, errors } = parse(text);
  const diagnostics: Diagnostic[] = [];

  for (const err of errors) {
    diagnostics.push({
      severity: DiagnosticSeverity.Error,
      range: {
        start: { line: err.line, character: 0 },
        end: { line: err.line, character: 100 },
      },
      message: err.message,
      source: 'tomlplus',
    });
  }

  // 型ミスマッチ — 簡単な例
  for (const k of keys) {
    if (k.type === 'int' && !/^\d+$/.test(k.value.trim())) {
      diagnostics.push({
        severity: DiagnosticSeverity.Warning,
        range: {
          start: { line: k.line, character: 0 },
          end: { line: k.line, character: k.range.end },
        },
        message: `Expected int, got "${k.value}"`,
        source: 'tomlplus',
      });
    }
  }

  connection.sendDiagnostics({ uri: doc.uri, diagnostics });
}

import { CompletionItem, CompletionItemKind } from 'vscode-languageserver/node';

connection.onCompletion(({ textDocument, position }): CompletionItem[] => {
  const doc = documents.get(textDocument.uri);
  if (!doc) return [];

  const text = doc.getText();
  const { keys } = parse(text);
  const linePrefix = doc
    .getText({ start: { line: position.line, character: 0 }, end: position })
    .trim();

  // $ で始まったら別セクションのキーを候補に。
  if (linePrefix.endsWith('$')) {
    return keys.map((k) => ({
      label: `${k.section}.${k.key}`,
      kind: CompletionItemKind.Variable,
      detail: `${k.type ?? 'any'} = ${k.value}`,
    }));
  }
  // 行頭ならキーの雛形を提示。
  return [
    { label: 'host: string = ', kind: CompletionItemKind.Snippet },
    { label: 'port: int = ', kind: CompletionItemKind.Snippet },
    { label: 'enabled: bool = ', kind: CompletionItemKind.Snippet },
  ];
});

connection.onCompletionResolve((item) => {
  // 重い情報を遅延ロードする枠。今は素通し。
  return item;
});

import { Hover } from 'vscode-languageserver/node';

connection.onHover(({ textDocument, position }): Hover | null => {
  const doc = documents.get(textDocument.uri);
  if (!doc) return null;

  const { keys } = parse(doc.getText());
  const lineText = doc.getText({
    start: { line: position.line, character: 0 },
    end: { line: position.line, character: 1000 },
  });
  const word = wordAt(lineText, position.character);
  if (!word) return null;

  const found = keys.find((k) => k.key === word);
  if (!found) return null;

  return {
    contents: {
      kind: 'markdown',
      value: `**${found.section}.${found.key}**\n\nType: \`${found.type ?? 'any'}\`\nValue: \`${found.value}\``,
    },
  };
});

connection.onDefinition(({ textDocument, position }) => {
  const doc = documents.get(textDocument.uri);
  if (!doc) return null;

  const { keys } = parse(doc.getText());
  const lineText = doc.getText({
    start: { line: position.line, character: 0 },
    end: { line: position.line, character: 1000 },
  });
  const ref = parseRef(lineText, position.character); // 例: {section:'server', key:'host'}
  if (!ref) return null;

  const target = keys.find((k) => k.section === ref.section && k.key === ref.key);
  if (!target) return null;

  return {
    uri: doc.uri,
    range: {
      start: { line: target.line, character: 0 },
      end: { line: target.line, character: target.range.end },
    },
  };
});

connection.onReferences(({ textDocument, position }) => {
  // 参照しているすべての行を見つけて Location[] を返す。onDefinition の逆。
  return findAllReferences(textDocument.uri, position);
});

import { WorkspaceEdit, TextEdit } from 'vscode-languageserver/node';

connection.onPrepareRename(({ textDocument, position }) => {
  const doc = documents.get(textDocument.uri);
  if (!doc) return null;
  const range = findIdentifierRange(doc, position);
  return range ?? null;
});

connection.onRenameRequest(({ textDocument, position, newName }): WorkspaceEdit => {
  const doc = documents.get(textDocument.uri)!;
  const locations = findAllOccurrences(doc, position);

  return {
    changes: {
      [doc.uri]: locations.map((loc) => TextEdit.replace(loc.range, newName)),
    },
  };
});

import { CodeAction, CodeActionKind } from 'vscode-languageserver/node';

connection.onCodeAction((params): CodeAction[] => {
  const doc = documents.get(params.textDocument.uri);
  if (!doc) return [];
  const actions: CodeAction[] = [];

  for (const diag of params.context.diagnostics) {
    if (diag.message.startsWith('Expected int')) {
      actions.push({
        title: 'Change type to "string"',
        kind: CodeActionKind.QuickFix,
        diagnostics: [diag],
        edit: {
          changes: {
            [doc.uri]: [TextEdit.replace(diag.range, fixTypeToString(doc, diag.range))],
          },
        },
      });
    }
  }
  return actions;
});

import { SemanticTokensBuilder } from 'vscode-languageserver/node';

connection.languages.semanticTokens.on(({ textDocument }) => {
  const doc = documents.get(textDocument.uri)!;
  const builder = new SemanticTokensBuilder();
  const { keys } = parse(doc.getText());

  for (const k of keys) {
    // [line, startChar, length, tokenType, tokenModifiers]
    builder.push(k.line, 0, k.key.length, /*property*/ 4, /*declaration*/ 1);
  }
  return builder.build();
});

connection.onDocumentFormatting(({ textDocument, options }) => {
  const doc = documents.get(textDocument.uri)!;
  const formatted = formatTomlPlus(doc.getText(), options);
  return [TextEdit.replace(
    {
      start: { line: 0, character: 0 },
      end: doc.positionAt(doc.getText().length),
    },
    formatted
  )];
});

import * as path from 'path';
import * as vscode from 'vscode';
import {
  LanguageClient,
  LanguageClientOptions,
  ServerOptions,
  TransportKind,
} from 'vscode-languageclient/node';

let client: LanguageClient;

export function activate(context: vscode.ExtensionContext) {
  const serverModule = context.asAbsolutePath(path.join('server', 'out', 'server.js'));

  const serverOptions: ServerOptions = {
    run: { module: serverModule, transport: TransportKind.ipc },
    debug: {
      module: serverModule,
      transport: TransportKind.ipc,
      options: { execArgv: ['--nolazy', '--inspect=6009'] },
    },
  };

  const clientOptions: LanguageClientOptions = {
    documentSelector: [{ scheme: 'file', language: 'tomlplus' }],
    synchronize: {
      fileEvents: vscode.workspace.createFileSystemWatcher('**/*.tomlplus'),
    },
  };

  client = new LanguageClient('tomlplus', 'TOML+ Language Server', serverOptions, clientOptions);
  client.start();
}

export function deactivate(): Thenable\<void\> | undefined {
  return client?.stop();
}

"contributes": {
  "languages": [{
    "id": "tomlplus",
    "extensions": [".tomlplus", ".tpl"],
    "configuration": "./language-configuration.json"
  }],
  "grammars": [{
    "language": "tomlplus",
    "scopeName": "source.tomlplus",
    "path": "./syntaxes/tomlplus.tmLanguage.json"
  }]
}

use tower_lsp::jsonrpc::Result;
use tower_lsp::lsp_types::*;
use tower_lsp::{Client, LanguageServer, LspService, Server};

#[derive(Debug)]
struct Backend {
    client: Client,
}

#[tower_lsp::async_trait]
impl LanguageServer for Backend {
    async fn initialize(&self, _: InitializeParams) -> Result\<InitializeResult\> {
        Ok(InitializeResult {
            capabilities: ServerCapabilities {
                text_document_sync: Some(TextDocumentSyncCapability::Kind(
                    TextDocumentSyncKind::INCREMENTAL,
                )),
                completion_provider: Some(CompletionOptions {
                    trigger_characters: Some(vec![".".into(), "$".into()]),
                    ..Default::default()
                }),
                hover_provider: Some(HoverProviderCapability::Simple(true)),
                definition_provider: Some(OneOf::Left(true)),
                ..Default::default()
            },
            server_info: Some(ServerInfo {
                name: "tomlplus-lsp".into(),
                version: Some("0.1.0".into()),
            }),
        })
    }

    async fn initialized(&self, _: InitializedParams) {
        self.client.log_message(MessageType::INFO, "server ready").await;
    }

    async fn did_change(&self, params: DidChangeTextDocumentParams) {
        let uri = params.text_document.uri.clone();
        let diags = validate(&params.content_changes);
        self.client.publish_diagnostics(uri, diags, None).await;
    }

    async fn completion(&self, _: CompletionParams) -> Result\<Option\<CompletionResponse\>\> {
        Ok(Some(CompletionResponse::Array(vec![
            CompletionItem::new_simple("host".into(), "hostname".into()),
            CompletionItem::new_simple("port".into(), "TCP port".into()),
        ])))
    }

    async fn shutdown(&self) -> Result\<()\> { Ok(()) }
}

#[tokio::main]
async fn main() {
    let stdin = tokio::io::stdin();
    let stdout = tokio::io::stdout();
    let (service, socket) = LspService::new(|client| Backend { client });
    Server::new(stdin, stdout, socket).serve(service).await;
}

[dependencies]
tower-lsp = "0.20"
tokio = { version = "1", features = ["full"] }

const serverOptions: ServerOptions = {
  command: context.asAbsolutePath('bin/tomlplus-lsp'),
  args: [],
  transport: TransportKind.stdio,
};

module.exports = grammar({
  name: 'tomlplus',
  rules: {
    source_file: ($) => repeat(choice($.section, $.assignment)),
    section: ($) => seq('[', $.identifier, ']'),
    assignment: ($) =>
      seq($.identifier, optional($.type_annotation), '=', $.value),
    type_annotation: ($) => seq(':', choice('int', 'string', 'bool')),
    value: ($) => choice($.string, $.number, $.reference),
    reference: ($) => seq('$', $.identifier, '.', $.identifier),
    identifier: ($) => /[a-zA-Z_][\w]*/,
    string: ($) => /"[^"]*"/,
    number: ($) => /\d+/,
  },
});

import Parser from 'tree-sitter';
import TomlPlus from 'tree-sitter-tomlplus';

const parser = new Parser();
parser.setLanguage(TomlPlus);

function parseDoc(text: string) {
  return parser.parse(text);
}

function reparse(oldTree: Parser.Tree, edit: Parser.Edit, newText: string) {
  oldTree.edit(edit);
  return parser.parse(newText, oldTree); // インクリメンタル
}

(section (identifier) @section.name)
(assignment
  (identifier) @key.name
  (type_annotation (_) @key.type)?
  (value) @key.value)
(reference
  (identifier) @ref.section
  (identifier) @ref.key)

[ユーザのキー入力]
       ↓
[VS Code クライアント]  ── didChange ──▶  [LSP サーバ]
                                              ↓
                                         [Tree-sitter インクリメンタル parse]
                                              ↓
                                         [シンボルインデックス更新]
                                              ↓
                                         publishDiagnostics、その他

npm install -g @vscode/vsce
cd tomlplus
vsce package
# → tomlplus-0.1.0.vsix

vsce login yj
vsce publish
# または: vsce publish minor / patch / major

npm install -g ovsx
ovsx create-namespace yj -p <ovsx-token>
ovsx publish tomlplus-0.1.0.vsix -p <ovsx-token>

- name: Publish to VS Marketplace
  run: vsce publish -p $\{\{ secrets.VSCE_PAT \}\}
- name: Publish to OpenVSX
  run: ovsx publish *.vsix -p $\{\{ secrets.OVSX_TOKEN \}\}

import TelemetryReporter from '@vscode/extension-telemetry';
const reporter = new TelemetryReporter('<connection-string>');
context.subscriptions.push(reporter);
reporter.sendTelemetryEvent('command.scanWorkspace');