From eb0a88514df344cbe4be3165cfa1a26af4f9f6ef Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Thu, 7 May 2020 16:44:33 -0400
Subject: [PATCH] fix: support linked monorepos (close #56)

---
 src/node/resolver.ts                         | 25 ++++++++++++++++----
 src/node/server/serverPluginHmr.ts           |  1 +
 src/node/server/serverPluginModuleResolve.ts | 17 +++++++++----
 3 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/src/node/resolver.ts b/src/node/resolver.ts
index 284ca569791443..6c2b7f3df61c77 100644
--- a/src/node/resolver.ts
+++ b/src/node/resolver.ts
@@ -2,6 +2,11 @@ import path from 'path'
 import slash from 'slash'
 import { statSync } from 'fs'
 import { cleanUrl } from './utils'
+import {
+  idToFileMap,
+  moduleRE,
+  fileToRequestMap
+} from './server/serverPluginModuleResolve'
 
 export interface Resolver {
   requestToFile(publicPath: string, root: string): string | undefined
@@ -15,11 +20,23 @@ export interface InternalResolver {
   idToRequest(id: string): string | undefined
 }
 
-const defaultRequestToFile = (publicPath: string, root: string) =>
-  path.join(root, publicPath.slice(1))
+const defaultRequestToFile = (publicPath: string, root: string): string => {
+  if (moduleRE.test(publicPath)) {
+    const moduleFilePath = idToFileMap.get(publicPath.replace(moduleRE, ''))
+    if (moduleFilePath) {
+      return moduleFilePath
+    }
+  }
+  return path.join(root, publicPath.slice(1))
+}
 
-const defaultFileToRequest = (filePath: string, root: string) =>
-  `/${slash(path.relative(root, filePath))}`
+const defaultFileToRequest = (filePath: string, root: string): string => {
+  const moduleRequest = fileToRequestMap.get(filePath)
+  if (moduleRequest) {
+    return moduleRequest
+  }
+  return `/${slash(path.relative(root, filePath))}`
+}
 
 const defaultIdToRequest = (id: string) => {
   if (id.startsWith('@') && id.indexOf('/') < 0) {
diff --git a/src/node/server/serverPluginHmr.ts b/src/node/server/serverPluginHmr.ts
index c1774439c55e89..4ff04b7c23ffe5 100644
--- a/src/node/server/serverPluginHmr.ts
+++ b/src/node/server/serverPluginHmr.ts
@@ -151,6 +151,7 @@ export const hmrPlugin: Plugin = ({ root, app, server, watcher, resolver }) => {
     const prevDescriptor = cacheEntry && cacheEntry.descriptor
     if (!prevDescriptor) {
       // the file has never been accessed yet
+      debugHmr(`no existing descriptor found for ${file}`)
       return
     }
 
diff --git a/src/node/server/serverPluginModuleResolve.ts b/src/node/server/serverPluginModuleResolve.ts
index f4b4242e16198b..a416556cc2109c 100644
--- a/src/node/server/serverPluginModuleResolve.ts
+++ b/src/node/server/serverPluginModuleResolve.ts
@@ -9,10 +9,11 @@ import slash from 'slash'
 const debug = require('debug')('vite:resolve')
 
 const idToEntryMap = new Map()
-const idToFileMap = new Map()
+export const idToFileMap = new Map()
+export const fileToRequestMap = new Map()
 const webModulesMap = new Map()
 
-const moduleRE = /^\/@modules\//
+export const moduleRE = /^\/@modules\//
 
 const getDebugPath = (root: string, p: string) => {
   const relative = path.relative(root, p)
@@ -20,7 +21,7 @@ const getDebugPath = (root: string, p: string) => {
 }
 
 // plugin for resolving /@modules/:id requests.
-export const moduleResolvePlugin: Plugin = ({ root, app }) => {
+export const moduleResolvePlugin: Plugin = ({ root, app, watcher }) => {
   app.use(async (ctx, next) => {
     if (!moduleRE.test(ctx.path)) {
       return next()
@@ -31,10 +32,16 @@ export const moduleResolvePlugin: Plugin = ({ root, app }) => {
 
     const serve = async (id: string, file: string, type: string) => {
       idToFileMap.set(id, file)
+      fileToRequestMap.set(file, ctx.path)
       debug(`(${type}) ${id} -> ${getDebugPath(root, file)}`)
-      // cached read sets etag, body and status on ctx so there is no need
-      // to go further to other middlewares.
       await cachedRead(ctx, file)
+
+      // resolved module file is outside of root dir, but is not in node_modules.
+      // this is likely a linked monorepo/workspace, watch the file for HMR.
+      if (!file.startsWith(root) && !/node_modules/.test(file)) {
+        watcher.add(file)
+      }
+      await next()
     }
 
     // special handling for vue's runtime.