feat: standalone bundler

src/fs/bundle.ts

@@ -0,0 +1,70 @@
+import { stat as getStat, Stats, createReadStream } from 'fs'
+import { relative } from 'path'
+import { Readable } from 'stream'
+import combineStreams = require('multistream')
+
+const stat = (file: string): Promise<Stats> => {
+  return new Promise((resolve, reject) => {
+    getStat(file, (err, stats) => (err ? reject(err) : resolve(stats)))
+  })
+}
+
+function makeRelative(cwd: string, path: string) {
+  return './' + relative(cwd, path)
+}
+
+export function toStream(content: Buffer | string) {
+  const readable = new Readable({ read() {} })
+  readable.push(content)
+  readable.push(null)
+  return readable
+}
+
+export type File = { absPath: string; contents: string; deps: FileMap }
+export type FileMap = { [absPath: string]: File | null }
+
+export interface BundleOptions {
+  entries: string[]
+  cwd: string
+  expand: boolean
+  loadContent: boolean
+  files: FileMap
+}
+
+export class Bundle {
+  constructor({ cwd }: { cwd: string } = { cwd: process.cwd() }) {
+    this.cwd = cwd
+  }
+  cwd: string
+  blobSize: number = 0
+  index: { [relativeFilePath: string]: [number, number] } = {}
+  streams: (Readable | (() => Readable))[] = []
+
+  async addResource(absoluteFileName: string, content?: Buffer | string) {
+    let length = 0
+    if (content) {
+      length = Buffer.byteLength(content)
+    } else {
+      const stats = await stat(absoluteFileName)
+      length = stats.size
+    }
+
+    const start = this.blobSize
+
+    this.blobSize += length
+    this.index[makeRelative(this.cwd, absoluteFileName)] = [start, length]
+    this.streams.push(() => (content ? toStream(content) : createReadStream(absoluteFileName)))
+  }
+
+  concat() {
+    throw new Error('Not Implemented')
+  }
+
+  toStream() {
+    return combineStreams(this.streams)
+  }
+
+  toJSON() {
+    return this.index
+  }
+}