Herb Language Server and Visual Studio Code Extension (#105)

This pull request adds a Herb Language Server Protocol implementation
and a Visual Studio Code Extension for it.

To be able to make the bundling work in CommonJS in VS Code I also
implemented a new `@herb-tools/node-wasm` package that uses the
WebAssembly build in `wasm/` to build a version of the libherb library
for the Node.js environment.

Ideally we can use the Node.js implementation in the future, but the
pre-compilation of the native Node.js Addon is trickier than initially
expected with Electron and the system architecture.

Author: marcoroth

javascript/packages/language-server/.gitignore

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+dist/
+build/
+node_modules/
+
+*~
+
+.DS_Store
+tsconfig.tsbuildinfo

javascript/packages/language-server/.npmignore

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+.babelrc
+.babelrc.js
+.DS_Store
+.gitignore
+.yarn.lock
+
+*.log
+*.tsbuildinfo
+*.tgz
+
+README.md
+rollup.config.js
+tsconfig.json
+tsconfig.tsbuildinfo
+yarn-error.log
+*~
+
+/.git
+/.github
+/.gitattributes
+
+/node_modules
+/src
+/test
+/coverage
+/assets

javascript/packages/language-server/.vscodeignore

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+.gitignore
+.node-version
+
+**/*.ts
+**/*.map
+**/tsconfig.json
+**/tsconfig.base.json
+
+scripts/**

javascript/packages/language-server/LICENSE.txt

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+MIT License
+
+Copyright (c) 2025 Marco Roth
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

javascript/packages/language-server/README.md

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+# Herb Language Server (`@herb-tools/language-server`)
+
+[Language Server Protocol](https://github.com/Microsoft/language-server-protocol) integration for HTML-aware ERB using the [Herb Parser](https://herb-tools.dev).
+
+![](./assets/herb-lsp.png)
+
+Used by the [Herb LSP](https://marketplace.visualstudio.com/items?itemName=marcoroth.herb-lsp) Visual Studio Code extension.
+
+## Install
+
+```bash
+npm install -g herb-language-server
+```
+
+```bash
+yarn global add herb-language-server
+```
+
+## Run
+
+```bash
+herb-language-server --stdio
+```
+
+```
+Usage: herb-language-server [options]
+
+Options:
+
+  --stdio          use stdio
+  --node-ipc       use node-ipc
+  --socket=<port>  use socket
+```

javascript/packages/language-server/assets/herb-lsp.png

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+{
+  "name": "@herb-tools/language-server",
+  "description": "Powerful and seamless HTML-aware ERB parsing and tooling.",
+  "version": "0.2.0",
+  "author": "Marco Roth",
+  "license": "MIT",
+  "engines": {
+    "node": "*"
+  },
+  "bugs": "https://github.com/marcoroth/herb/issues/new?title=Package%20%60@herb-tools/language-server%60:%20",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/marcoroth/herb.git",
+    "directory": "javascript/packages/language-server"
+  },
+  "homepage": "https://herb-tools.dev",
+  "bin": {
+    "herb-language-server": "./dist/herb-language-server"
+  },
+  "scripts": {
+    "clean": "rimraf dist",
+    "prebuild": "yarn run clean",
+    "build": "tsc -b && rollup -c rollup.config.mjs",
+    "postbuild": "node scripts/executable.mjs",
+    "watch": "tsc -b -w"
+  },
+  "files": [
+    "dist"
+  ],
+  "dependencies": {
+    "@herb-tools/node-wasm": "0.2.0",
+    "dedent": "^1.6.0",
+    "typescript": "^5.8.3",
+    "vscode-languageserver": "^9.0.1",
+    "vscode-languageserver-textdocument": "^1.0.12"
+  },
+  "devDependencies": {
+    "@rollup/plugin-commonjs": "^28.0.6",
+    "@rollup/plugin-typescript": "^12.1.3",
+    "@rollup/plugin-node-resolve": "^16.0.1",
+    "@rollup/plugin-json": "^6.1.0",
+    "rimraf": "^6.0.1"
+  }
+}

javascript/packages/language-server/assets/herb.svg

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+import typescript from "@rollup/plugin-typescript"
+import { nodeResolve } from "@rollup/plugin-node-resolve"
+import json from "@rollup/plugin-json"
+import commonjs from "@rollup/plugin-commonjs"
+
+// Bundle the LSP server entry point into a single CommonJS file.
+// Exclude Node built-in so they remain as externals.
+const external = [
+  "path",
+  "url",
+  "fs",
+  "module",
+]
+
+function isExternal(id) {
+  return (
+    external.includes(id) ||
+    external.some((pkg) => id === pkg || id.startsWith(pkg + "/"))
+  )
+}
+
+export default {
+  input: "src/server.ts",
+  output: {
+    file: "dist/herb-language-server.js",
+    format: "cjs",
+    sourcemap: true,
+  },
+  external: isExternal,
+  plugins: [
+    nodeResolve(),
+    commonjs(),
+    json(),
+    typescript({
+      tsconfig: "./tsconfig.json",
+      rootDir: "src/",
+      module: "esnext",
+    }),
+  ],
+}

javascript/packages/language-server/package.json

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+import { readFileSync, writeFileSync } from 'fs'
+import { dirname, resolve } from 'path'
+import { fileURLToPath } from 'url'
+import { exec } from 'child_process'
+
+const __dirname = dirname(fileURLToPath(import.meta.url))
+
+const infile = resolve(__dirname, '../dist/herb-language-server.js')
+const outfile = resolve(__dirname, '../dist/herb-language-server')
+
+writeFileSync(
+  outfile,
+  '#!/usr/bin/env node\n' + readFileSync(infile, 'utf-8'),
+  'utf-8'
+)
+
+exec('chmod +x dist/herb-language-server', (error, _stdout, _stderr) => {
+  if (error) {
+    console.error(`Error setting file permissions: ${error}`);
+  } else {
+    console.log('File permissions set successfully');
+  }
+});