Change to replace Buffer with Uint8Array

Previously, this project depended on Node’s buffer.
This commit changes that: it replaces that support with `Uint8Array`.
In most cases, this will be fine, because the Node `Buffer` class subclasses
`Uint8Array`.
However, there are differences in which encodings are supported when turning
this binary data into a string, and there are differences in how methods work.

Closes GH-85.

Reviewed-by: Christian Murphy <christian.murphy.42@gmail.com>

index.d.ts

@@ -1,22 +1,9 @@
-/**
- * This is the same as `Buffer` if node types are included, `never` otherwise.
- */
-// eslint-disable-next-line @typescript-eslint/ban-ts-comment, @typescript-eslint/prefer-ts-expect-error
-// @ts-ignore It’s important to preserve this ignore statement. This makes sure
-// it works both with and without node types.
-// eslint-disable-next-line n/prefer-global/buffer
-type MaybeBuffer = any extends Buffer ? never : Buffer
-
 /**
  * Contents of the file.
  *
- * Can either be text or a `Buffer` structure.
+ * Can either be text or a `Uint8Array` structure.
  */
-// Note: this does not directly use type `Buffer`, because it can also be used
-// in a browser context.
-// Instead this leverages `Uint8Array` which is the base type for `Buffer`,
-// and a native JavaScript construct.
-export type Value = MaybeBuffer | string
+export type Value = Uint8Array | string
 
 /**
  * This map registers the type of the `data` key of a `VFile`.
@@ -49,7 +36,6 @@ export type {Data as VFileData, DataMap as VFileDataMap, Value as VFileValue}
 export {VFile} from './lib/index.js'
 
 export type {
-  BufferEncoding,
   Compatible,
   Map,
   MessageOptions,

lib/index.js

@@ -10,13 +10,6 @@
 /**
  * @typedef {object & {type: string, position?: Position | undefined}} NodeLike
  *
- * @typedef {'ascii' | 'base64' | 'base64url' | 'binary' | 'hex' | 'latin1' | 'ucs-2' | 'ucs2' | 'utf-8' | 'utf16le' | 'utf8'} BufferEncoding
- *   Encodings supported by the buffer class.
- *
- *   This is a copy of the types from Node, copied to prevent Node globals from
- *   being needed.
- *   Copied from: <https://github.com/DefinitelyTyped/DefinitelyTyped/blob/1761eec/types/node/buffer.d.ts#L223>
- *
  * @typedef {Options | URL | VFile | Value} Compatible
  *   Things that can be passed to the constructor.
  *
@@ -83,7 +76,6 @@
  *   Report.
  */
 
-import bufferLike from 'is-buffer'
 import {VFileMessage} from 'vfile-message'
 import {path} from 'vfile/do-not-use-conditional-minpath'
 import {proc} from 'vfile/do-not-use-conditional-minproc'
@@ -109,7 +101,7 @@ export class VFile {
    *
    * `options` is treated as:
    *
-   * *   `string` or `Buffer` — `{value: options}`
+   * *   `string` or `Uint8Array` — `{value: options}`
    * *   `URL` — `{path: options}`
    * *   `VFile` — shallow copies its data over to the new file
    * *   `object` — all fields are shallow copied over to the new file
@@ -132,10 +124,10 @@ export class VFile {
 
     if (!value) {
       options = {}
-    } else if (typeof value === 'string' || buffer(value)) {
-      options = {value}
     } else if (isUrl(value)) {
       options = {path: value}
+    } else if (typeof value === 'string' || isUint8Array(value)) {
+      options = {value}
     } else {
       options = value
     }
@@ -619,14 +611,27 @@ export class VFile {
   /**
    * Serialize the file.
    *
-   * @param {BufferEncoding | null | undefined} [encoding='utf8']
-   *   Character encoding to understand `value` as when it’s a `Buffer`
-   *   (default: `'utf8'`).
+   * > **Note**: which encodings are supported depends on the engine.
+   * > For info on Node.js, see:
+   * > <https://nodejs.org/api/util.html#whatwg-supported-encodings>.
+   *
+   * @param {string | null | undefined} [encoding='utf8']
+   *   Character encoding to understand `value` as when it’s a `Uint8Array`
+   *   (default: `'utf-8'`).
    * @returns {string}
    *   Serialized file.
    */
   toString(encoding) {
-    return (this.value || '').toString(encoding || undefined)
+    if (this.value === undefined) {
+      return ''
+    }
+
+    if (typeof this.value === 'string') {
+      return this.value
+    }
+
+    const decoder = new TextDecoder(encoding || undefined)
+    return decoder.decode(this.value)
   }
 }
 
@@ -681,13 +686,18 @@ function assertPath(path, name) {
 }
 
 /**
- * Assert `value` is a buffer.
+ * Assert `value` is an `Uint8Array`.
  *
  * @param {unknown} value
  *   thing.
- * @returns {value is Buffer}
- *   Whether `value` is a Node.js buffer.
+ * @returns {value is Uint8Array}
+ *   Whether `value` is an `Uint8Array`.
  */
-function buffer(value) {
-  return bufferLike(value)
+function isUint8Array(value) {
+  return Boolean(
+    value &&
+      typeof value === 'object' &&
+      'byteLength' in value &&
+      'byteOffset' in value
+  )
 }

package.json

@@ -55,7 +55,6 @@
   ],
   "dependencies": {
     "@types/unist": "^2.0.0",
-    "is-buffer": "^2.0.0",
     "unist-util-stringify-position": "^3.0.0",
     "vfile-message": "^4.0.0"
   },

readme.md

@@ -37,7 +37,6 @@ metadata about files (such as its `path` and `value`) and lint
     *   [`VFile#info(reason[, options])`](#vfileinforeason-options)
     *   [`VFile#message(reason[, options])`](#vfilemessagereason-options)
     *   [`VFile#toString(encoding?)`](#vfiletostringencoding)
-    *   [`BufferEncoding`](#bufferencoding)
     *   [`Compatible`](#compatible)
     *   [`Data`](#data)
     *   [`DataMap`](#datamap)
@@ -170,7 +169,7 @@ Create a new virtual file.
 
 `options` is treated as:
 
-*   `string` or [`Buffer`][buffer] — `{value: options}`
+*   `string` or [`Uint8Array`][mdn-uint8-array] — `{value: options}`
 *   `URL` — `{path: options}`
 *   `VFile` — shallow copies its data over to the new file
 *   `object` — all fields are shallow copied over to the new file
@@ -196,7 +195,7 @@ New instance (`VFile`).
 ```js
 new VFile()
 new VFile('console.log("alpha");')
-new VFile(Buffer.from('exit 1'))
+new VFile(new Uint8Array([0x65, 0x78, 0x69, 0x74, 0x20, 0x31]))
 new VFile({path: path.join('path', 'to', 'readme.md')})
 new VFile({stem: 'readme', extname: '.md', dirname: path.join('path', 'to')})
 new VFile({other: 'properties', are: 'copied', ov: {e: 'r'}})
@@ -226,7 +225,7 @@ List of messages associated with the file
 
 ### `file.value`
 
-Raw value ([`Buffer`][buffer], `string`, `undefined`).
+Raw value ([`Uint8Array`][mdn-uint8-array], `string`, `undefined`).
 
 ### `file.basename`
 
@@ -337,39 +336,20 @@ Message ([`VFileMessage`][vmessage]).
 
 Serialize the file.
 
+> **Note**: which encodings are supported depends on the engine.
+> For info on Node.js, see:
+> <https://nodejs.org/api/util.html#whatwg-supported-encodings>.
+
 ###### Parameters
 
-*   `encoding` ([`BufferEncoding`][api-buffer-encoding], default: `'utf8'`)
+*   `encoding` (`string`, default: `'utf8'`)
     — character encoding to understand `value` as when it’s a
-    [`Buffer`][buffer]
+    [`Uint8Array`][mdn-uint8-array]
 
 ###### Returns
 
 Serialized file (`string`).
 
-### `BufferEncoding`
-
-[Encodings][encoding] supported by the [buffer][] class (TypeScript type).
-
-This is a copy of the types from Node.
-
-###### Type
-
-```ts
-type BufferEncoding =
-  | 'ascii'
-  | 'base64'
-  | 'base64url'
-  | 'binary'
-  | 'hex'
-  | 'latin1'
-  | 'ucs-2'
-  | 'ucs2'
-  | 'utf-8'
-  | 'utf16le'
-  | 'utf8'
-```
-
 ### `Compatible`
 
 Things that can be passed to the constructor (TypeScript type).
@@ -497,12 +477,12 @@ type ReporterSettings = Record<string, unknown>
 
 Contents of the file (TypeScript type).
 
-Can either be text or a `Buffer` structure.
+Can either be text or a [`Uint8Array`][mdn-uint8-array] structure.
 
 ###### Type
 
 ```ts
-type Value = Buffer | string
+type Value = Uint8Array | string
 ```
 
 ### Well-known
@@ -586,7 +566,6 @@ There are also well-known fields on messages, see
 
 This package is fully typed with [TypeScript][].
 It exports the additional types
-[`BufferEncoding`][api-buffer-encoding],
 [`Compatible`][api-compatible],
 [`Data`][api-data],
 [`DataMap`][api-data-map],
@@ -773,9 +752,7 @@ for contributing commits since!
 
 [vfile-message-options]: https://github.com/vfile/vfile-message#options
 
-[encoding]: https://nodejs.org/api/buffer.html#buffer_buffers_and_character_encodings
-
-[buffer]: https://nodejs.org/api/buffer.html
+[mdn-uint8-array]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array
 
 [source-map]: https://github.com/mozilla/source-map/blob/58819f0/source-map.d.ts#L15-L23
 
@@ -789,8 +766,6 @@ for contributing commits since!
 
 [api-vfile]: #vfileoptions
 
-[api-buffer-encoding]: #bufferencoding
-
 [api-compatible]: #compatible
 
 [api-data]: #data

test.js

@@ -160,15 +160,25 @@ test('new VFile(options?)', async function (t) {
     )
 
     assert.equal(
-      new VFile(Buffer.from('bar')).toString(),
-      'bar',
-      'buffer: should return the internal value'
+      new VFile(Buffer.from([0xef, 0xbb, 0xbf, 0x61, 0x62, 0x63])).toString(),
+      'abc',
+      'should return the internal value (`Buffer`, default: utf8)'
     )
 
     assert.equal(
-      new VFile(Buffer.from('bar')).toString('hex'),
-      '626172',
-      'buffer encoding: should return the internal value'
+      new VFile(
+        new Uint8Array([0xfe, 0xff, 0x00, 0x61, 0x00, 0x62, 0x00, 0x63])
+      ).toString('utf-16be'),
+      'abc',
+      'should return the internal value (`Uint8Array`, explicit utf-16be)'
+    )
+
+    assert.equal(
+      new VFile(
+        new Uint8Array([0xff, 0xfe, 0x61, 0x00, 0x62, 0x00, 0x63, 0x00])
+      ).toString('utf-16le'),
+      'abc',
+      'should return the internal value (`Uint8Array`, explicit utf-16le)'
     )
   })