fix(@ngtools/webpack): support watching file replacements

Author: clydin

packages/ngtools/webpack/src/angular_compiler_plugin.ts

@@ -5,7 +5,7 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
-import { dirname, normalize, resolve, virtualFs } from '@angular-devkit/core';
+import { Path, dirname, normalize, resolve, virtualFs } from '@angular-devkit/core';
 import { NodeJsSyncHost } from '@angular-devkit/core/node';
 import { ChildProcess, ForkOptions, fork } from 'child_process';
 import * as fs from 'fs';
@@ -617,8 +617,21 @@ export class AngularCompilerPlugin {
         this._compilerHost,
       );
       compilerWithFileSystems.inputFileSystem = inputDecorator;
+
+      let replacements: Map<Path, Path> | undefined;
+      if (this._options.hostReplacementPaths) {
+        replacements = new Map();
+        for (const replace in this._options.hostReplacementPaths) {
+          replacements.set(
+            normalize(replace),
+            normalize(this._options.hostReplacementPaths[replace]),
+          );
+        }
+      }
+
       compilerWithFileSystems.watchFileSystem = new VirtualWatchFileSystemDecorator(
         inputDecorator,
+        replacements,
       );
     });
 

packages/ngtools/webpack/src/virtual_file_system_decorator.ts

@@ -5,6 +5,7 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+import { Path, getSystemPath, normalize } from '@angular-devkit/core';
 import { Stats } from 'fs';
 import { WebpackCompilerHost } from './compiler_host';
 import { Callback, InputFileSystem, NodeWatchFileSystemInterface } from './webpack';
@@ -105,24 +106,27 @@ export class VirtualFileSystemDecorator implements InputFileSystem {
 }
 
 export class VirtualWatchFileSystemDecorator extends NodeWatchFileSystem {
-  constructor(private _virtualInputFileSystem: VirtualFileSystemDecorator) {
+  constructor(
+    private _virtualInputFileSystem: VirtualFileSystemDecorator,
+    private _replacements?: Map<Path, Path>,
+  ) {
     super(_virtualInputFileSystem);
   }
 
   watch(
-    files: any,  // tslint:disable-line:no-any
-    dirs: any,  // tslint:disable-line:no-any
-    missing: any,  // tslint:disable-line:no-any
-    startTime: any,  // tslint:disable-line:no-any
-    options: any,  // tslint:disable-line:no-any
+    files: string[],
+    dirs: string[],
+    missing: string[],
+    startTime: number | undefined,
+    options: {},
     callback: any,  // tslint:disable-line:no-any
     callbackUndelayed: any,  // tslint:disable-line:no-any
   ) {
     const newCallback = (
-      err: any,  // tslint:disable-line:no-any
-      filesModified: any,  // tslint:disable-line:no-any
-      contextModified: any,  // tslint:disable-line:no-any
-      missingModified: any,  // tslint:disable-line:no-any
+      err: Error | null,
+      filesModified: string[],
+      contextModified: string[],
+      missingModified: string[],
       fileTimestamps: { [k: string]: number },
       contextTimestamps: { [k: string]: number },
     ) => {
@@ -137,6 +141,30 @@ export class VirtualWatchFileSystemDecorator extends NodeWatchFileSystem {
         contextTimestamps);
     };
 
-    return super.watch(files, dirs, missing, startTime, options, newCallback, callbackUndelayed);
+    const mapReplacements = (original: string[]): string[] => {
+      if (!this._replacements) {
+        return original;
+      }
+      const replacements = this._replacements;
+
+      return original.map(file => {
+        const replacement = replacements.get(normalize(file));
+        if (replacement) {
+          return getSystemPath(replacement);
+        } else {
+          return file;
+        }
+      });
+    };
+
+    return super.watch(
+      mapReplacements(files),
+      mapReplacements(dirs),
+      mapReplacements(missing),
+      startTime,
+      options,
+      newCallback,
+      callbackUndelayed,
+    );
   }
 }