Support watching feature

.eslintrc.js

@@ -5,6 +5,9 @@ module.exports = {
     'object-curly-newline': ['error', { multiline: true, consistent: true }],
     semi: ['error', 'never']
   },
+  ignorePatterns: [
+    'index.d.ts'
+  ],
   env: {
     jest: true
   }

index.d.ts

@@ -1,62 +1,76 @@
-import rollup from 'rollup';
-import fs from 'fs-extra';
-import globby from 'globby';
-
-interface Target extends globby.GlobbyOptions {
-    /**
-     * Path or glob of what to copy.
-     */
-    readonly src: string | readonly string[];
-
-    /**
-     * One or more destinations where to copy.
-     */
-    readonly dest: string | readonly string[];
-
-    /**
-     * Change destination file or folder name.
-     */
-    readonly rename?: string | Function;
-
-    /**
-     * Modify file contents.
-     */
-    readonly transform?: Function;
+import rollup from 'rollup'
+import fs from 'fs-extra'
+import globby from 'globby'
+
+
+export interface Target extends globby.GlobbyOptions {
+  /**
+   * Path or glob of what to copy.
+   */
+  readonly src: string | readonly string[]
+
+  /**
+   * One or more destinations where to copy.
+   */
+  readonly dest: string | readonly string[]
+
+  /**
+   * Change destination file or folder name.
+   */
+  readonly rename?: string | ((fileName: string, fileExt: string) => string)
+  /**
+   * Modify file contents.
+   */
+  readonly transform?: (
+    content: string | ArrayBuffer,
+    srcPath: string,
+    destPath: string
+  ) => string | ArrayBuffer
 }
 
-interface CopyOptions extends globby.GlobbyOptions, fs.CopyOptions {
-    /**
-     * Copy items once. Useful in watch mode.
-     * @default false
-     */
-    readonly copyOnce?: boolean;
-
-    /**
-     * Remove the directory structure of copied files.
-     * @default true
-     */
-    readonly flatten?: boolean;
-
-    /**
-     * Rollup hook the plugin should use.
-     * @default 'buildEnd'
-     */
-    readonly hook?: string;
-
-    /**
-     * Array of targets to copy.
-     * @default []
-     */
-    readonly targets?: readonly Target[];
-
-    /**
-     * Output copied items to console.
-     * @default false
-     */
-    readonly verbose?: boolean;
+
+export interface CopyOptions extends globby.GlobbyOptions, fs.CopyOptions {
+  /**
+   * Copy items once. Useful in watch mode.
+   * @default false
+   */
+  readonly copyOnce?: boolean
+
+  /**
+   * Remove the directory structure of copied files.
+   * @default true
+   */
+  readonly flatten?: boolean
+
+  /**
+   * Rollup hook the plugin should use.
+   * @default 'buildEnd'
+   */
+  readonly hook?: string
+
+  /**
+   * Rollup hook the `this.addWatchFile` should call, only be used in hooks
+   * during the build phase, and must be processed earlier than hook
+   * @default 'buildStart'
+   * @see https://rollupjs.org/guide/en/#thisaddwatchfileid-string--void
+   */
+  readonly watchStart?: 'buildStart' | 'load' | 'resolveId' | 'transform' | string
+
+  /**
+   * Array of targets to copy.
+   * @default []
+   */
+  readonly targets?: readonly Target[]
+
+  /**
+   * Output copied items to console.
+   * @default false
+   */
+  readonly verbose?: boolean
 }
 
+
 /**
  * Copy files and folders using Rollup
  */
-export default function copy(options?: CopyOptions): rollup.Plugin;
+export default function copy(options?: CopyOptions): rollup.Plugin

readme.md

@@ -142,7 +142,12 @@ copy({
   targets: [{
     src: 'src/index.html',
     dest: 'dist/public',
-    transform: (contents) => contents.toString().replace('__SCRIPT__', 'app.js')
+    transform: (contents, srcPath, destPath) => (
+      contents.toString()
+        .replace('__SCRIPT__', 'app.js')
+        .replace('__SOURCE_FILE_PATH__', srcPath)
+        .replace('__TARGET_FILE_NAME__', path.basename(srcPath))
+    )
   }]
 })
 ```
@@ -173,6 +178,21 @@ copy({
 })
 ```
 
+#### watchHook
+
+Type: `string` | Default: `buildStart`
+
+[Rollup hook](https://rollupjs.org/guide/en/#hooks) the [this.addWatchFile](https://rollupjs.org/guide/en/#thisaddwatchfileid-string--void) should call. By default, `addWatchFile` called on each rollup.rollup build.
+Only be used in hooks during the build phase, i.e. in `buildStart`, `load`, `resolveId`, and `transform`.
+
+```js
+copy({
+  targets: [{ src: 'assets/*', dest: 'dist/public' }],
+  watchHook: 'resolveId'
+})
+```
+
+
 #### copyOnce
 
 Type: `boolean` | Default: `false`