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Class fields support for acorn

License: MIT License

JavaScript 100.00%

acorn-class-fields's Introduction

Class fields support for Acorn

This is a plugin for Acorn - a tiny, fast JavaScript parser, written completely in JavaScript.

It implements support for class fields as defined in the stage 3 proposal Class field declarations for JavaScript. The emitted AST follows the ESTree experimental Class Features design.

Usage

This module provides a plugin that can be used to extend the Acorn Parser class:

const {Parser} = require('acorn');
const classFields = require('acorn-class-fields');
Parser.extend(classFields).parse('class X { x = 0 }');

License

This plugin is released under an MIT License.

acorn-class-fields's People

Contributors

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Watchers

Forkers

cfware guybedford bmeurer tchetwin dnalborczyk marvinhagemeister

acorn-class-fields's Issues

parse error when propertyName is number

field error ( acorn-class-fields )

'use strict';
Error.stackTraceLimit = 100;
require('acorn').Parser.extend( require('acorn-class-fields')                                         ).parse('class X { 1 = 1; }');

SyntaxError: Unexpected token (1:12)
    at Object.pp$4.raise (/node_modules/acorn/dist/acorn.js:2825:15)
    at Object.pp.unexpected (/node_modules/acorn/dist/acorn.js:689:10)
    at Object.pp.expect (/node_modules/acorn/dist/acorn.js:683:28)
    at Object.pp$3.parseMethod (/node_modules/acorn/dist/acorn.js:2609:10)
    at Object.pp$1.parseClassMethod (/node_modules/acorn/dist/acorn.js:1387:25)
    
    at Object.pp$1.parseClassElement (/node_modules/acorn/dist/acorn.js:1376:10)
    
    at Object.parseClassElement (/node_modules/acorn-class-fields/index.js:49:38)
    
    at Object.pp$1.parseClass (/node_modules/acorn/dist/acorn.js:1315:26)
    at Object.parseClass (/node_modules/acorn-class-fields/node_modules/acorn-private-class-elements/index.js:78:29)
    at Object.pp$1.parseStatement (/node_modules/acorn/dist/acorn.js:833:19)
    at Object.pp$1.parseTopLevel (/node_modules/acorn/dist/acorn.js:746:23)
    at Object.parse (/node_modules/acorn/dist/acorn.js:553:17)
    at Function.parse (/node_modules/acorn/dist/acorn.js:576:37)
    at Object.<anonymous> (/TEST.js:3:105)
    at Module._compile (internal/modules/cjs/loader.js:955:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:991:10)
    at Module.load (internal/modules/cjs/loader.js:811:32)
    at Function.Module._load (internal/modules/cjs/loader.js:723:14)
    at Function.Module.runMain (internal/modules/cjs/loader.js:1043:10)
    at internal/main/run_main_module.js:17:11

field error ( acorn-class-fields, acorn-static-class-features )

'use strict';
Error.stackTraceLimit = 100;
require('acorn').Parser.extend( require('acorn-class-fields'), require('acorn-static-class-features') ).parse('class X { 1 = 1; }');

SyntaxError: Unexpected token (1:12)
    at Object.pp$4.raise (/node_modules/acorn/dist/acorn.js:2825:15)
    at Object.pp.unexpected (/node_modules/acorn/dist/acorn.js:689:10)
    at Object.pp.expect (/node_modules/acorn/dist/acorn.js:683:28)
    at Object.pp$3.parseMethod (/node_modules/acorn/dist/acorn.js:2609:10)
    at Object.pp$1.parseClassMethod (/node_modules/acorn/dist/acorn.js:1387:25)
    at Object.parseClassMethod (/node_modules/acorn-static-class-features/index.js:110:39)
    at Object.pp$1.parseClassElement (/node_modules/acorn/dist/acorn.js:1376:10)
    
    at Object.parseClassElement (/node_modules/acorn-class-fields/index.js:49:38)
    at Object.parseClassElement (/node_modules/acorn-static-class-features/index.js:43:56)
    at Object.pp$1.parseClass (/node_modules/acorn/dist/acorn.js:1315:26)
    at Object.parseClass (/node_modules/acorn-class-fields/node_modules/acorn-private-class-elements/index.js:78:29)
    at Object.pp$1.parseStatement (/node_modules/acorn/dist/acorn.js:833:19)
    at Object.pp$1.parseTopLevel (/node_modules/acorn/dist/acorn.js:746:23)
    at Object.parse (/node_modules/acorn/dist/acorn.js:553:17)
    at Function.parse (/node_modules/acorn/dist/acorn.js:576:37)
    at Object.<anonymous> (/TEST.js:3:105)
    at Module._compile (internal/modules/cjs/loader.js:955:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:991:10)
    at Module.load (internal/modules/cjs/loader.js:811:32)
    at Function.Module._load (internal/modules/cjs/loader.js:723:14)
    at Function.Module.runMain (internal/modules/cjs/loader.js:1043:10)
    at internal/main/run_main_module.js:17:11

field error ( acorn-static-class-features, acorn-class-fields )

'use strict';
Error.stackTraceLimit = 100;
require('acorn').Parser.extend( require('acorn-static-class-features'), require('acorn-class-fields') ).parse('class X { 1 = 1; }');

SyntaxError: Unexpected token (1:12)
    at Object.pp$4.raise (/node_modules/acorn/dist/acorn.js:2825:15)
    at Object.pp.unexpected (/node_modules/acorn/dist/acorn.js:689:10)
    at Object.pp.expect (/node_modules/acorn/dist/acorn.js:683:28)
    at Object.pp$3.parseMethod (/node_modules/acorn/dist/acorn.js:2609:10)
    at Object.pp$1.parseClassMethod (/node_modules/acorn/dist/acorn.js:1387:25)
    at Object.parseClassMethod (/node_modules/acorn-static-class-features/index.js:110:39)
    at Object.pp$1.parseClassElement (/node_modules/acorn/dist/acorn.js:1376:10)
    at Object.parseClassElement (/node_modules/acorn-static-class-features/index.js:43:56)
    at Object.parseClassElement (/node_modules/acorn-class-fields/index.js:49:38)
    
    at Object.pp$1.parseClass (/node_modules/acorn/dist/acorn.js:1315:26)
    at Object.parseClass (/node_modules/acorn-static-class-features/node_modules/acorn-private-class-elements/index.js:78:29)
    at Object.pp$1.parseStatement (/node_modules/acorn/dist/acorn.js:833:19)
    at Object.pp$1.parseTopLevel (/node_modules/acorn/dist/acorn.js:746:23)
    at Object.parse (/node_modules/acorn/dist/acorn.js:553:17)
    at Function.parse (/node_modules/acorn/dist/acorn.js:576:37)
    at Object.<anonymous> (/TEST.js:3:105)
    at Module._compile (internal/modules/cjs/loader.js:955:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:991:10)
    at Module.load (internal/modules/cjs/loader.js:811:32)
    at Function.Module._load (internal/modules/cjs/loader.js:723:14)
    at Function.Module.runMain (internal/modules/cjs/loader.js:1043:10)
    at internal/main/run_main_module.js:17:11

static right

There is no error when parse class X { static 1 = 1; }.

Call to acorn-private-class-elements fails with "does not support mixing different acorn copies"

Currently using is as a rollup plugin, with rollup 2.1.0.

Expected behaviour:

rollup bundling works

Actual behaviour:

acorn-class-fields fails in index.js at line 17:
Parser = privateClassElements(Parser)

and this Error is thrown:

[!] Error: acorn-private-class-elements does not support mixing different acorn copies Error: acorn-private-class-elements does not support mixing different acorn copies

Proposed solution

This happens because acorn-private-class-elements expects the Parser object from acorn, so calling it like this

Parser = privateClassElements(acorn.Parser)

solved the issue for me. I hope I'm on the right track and that this can be fixed! Cheers :)

Can I use it as an Injector ?

Hi.

I'm trying to run this plugin with https://github.com/i18next/i18next-parser

Like this

const injectAcornStaticClassPropertyInitializer = require('acorn-static-class-property-initializer/inject');
const classFields = require('acorn-class-fields');

const js = [
    {
        lexer: 'JsxLexer',
        attr: 'i18nKey', // Attribute for the keys

        // acorn config (for more information on the acorn options, see here: https://github.com/acornjs/acorn#main-parser)
        acorn: {
            sourceType: 'module',
            ecmaVersion: 10, // forward compatibility
            injectors: [classFields, injectAcornStaticClassPropertyInitializer],
            plugins: { staticClassPropertyInitializer: true, classFields: true }
        }
    }
];

...

And I have this error


  [read]  /project/frontend/src/app/Market/Chart/index.js
/project/node_modules/i18next-parser/dist/parser.js:70
        }} catch (err) {_didIteratorError = true;_iteratorError = err;} finally {try {if (!_iteratorNormalCompletion && _iterator.return) {_iterator.return();}} finally {if (_didIteratorError) {throw _iteratorError;}}}
                                                                                                                                                                                                  ^

TypeError: Class extends value #<Object> is not a constructor or null
    at module.exports (/project/node_modules/acorn-class-fields/index.js:30:3)
    at /project/node_modules/i18next-parser/dist/lexers/javascript-lexer.js:31:48
    at Array.reduce (<anonymous>)
    at JsxLexer.JavascriptLexer (/project/node_modules/i18next-parser/dist/lexers/javascript-lexer.js:30:34)
    at new JsxLexer (/project/node_modules/i18next-parser/dist/lexers/jsx-lexer.js:36:106)
    at Parser.parse (/project/node_modules/i18next-parser/dist/parser.js:67:23)
    at i18nTransform._transform (/project/node_modules/i18next-parser/dist/transform.js:70:33)
    at i18nTransform.Transform._read (_stream_transform.js:190:10)
    at i18nTransform.Transform._write (_stream_transform.js:178:12)
    at doWrite (_stream_writable.js:410:12)

Is this because of a way acorn-class-fields initializes ?
My acorn deps are:

    "acorn-class-fields": "^0.2.1",
    "acorn-jsx": "^4.1.1",
    "acorn-stage3": "^0.6.0",
    "acorn-static-class-property-initializer": "^1.0.0",

Parse error when "super" is used

Originally via rollup/rollup#3505, which bundles this plugin at the moment:

It is not possible to use super in class properties even though it probably should, at least according to https://2ality.com/2019/07/public-class-fields.html#the-scope-of-field-initializers (I know this is not official documentation...)

At the moment the following throws with a SyntaxError: 'super' keyword outside a method:

require('acorn')
  .Parser.extend(require('acorn-class-fields'), require('acorn-static-class-features'))
  .parse('class SubClass extends SuperClass { prop = super.getValue(); }');

Does not support top-level await

For example the following code:

export default class RequestParams {
    constructor(storage) {
        this._storage = storage;
    }

    headers = {
        'Authorization': await this._storage.getItem(`${domainPrefix}.auth.lockchain`),
        'Accept': 'application/json',
        'Content-Type': 'application/json',
        'X-Device-Version': '49365f68-42e1-11e8-842f-0ed5f89f718b'
    }
}

will throw an error due to the await keyword.

parse error when propertyName is keyword

class Sample {
    class = 1;
}

Doesnt seem to work

https://npm.runkit.com/acorn-class-fields

Throws syntax error on:

var acornClassFields = require("acorn-class-fields")

var ast = acornClassFields.parse(`
    
    class Test {
        x = 10;
       constructor(){
 
       }
    }

`, {
  plugins: { classFields: true }
});

feature-request: add support for private methods

⚠️ Note: I've no knowledge of how this library works, I got some issues with vitest and was redirected to here.

Vitest isn't able to parse the # symbol of #private fields in a class. It seems that vitest uses this plugin under the hood, so it would be great if you can add support for private methods.

I've created an mcve for this issue that you can find here: stackblitz.com/edit/node-stkuzb

Breaking change: support new AST shape defined in estree/experimental

Now that class features reaches stage 3 and shipped in many browsers, people begin trying on this feature. It will be great if acorn can implement https://github.com/estree/estree/blob/master/experimental/class-features.md (even in a stage 3 plugin) so @babel/eslint-parser can align to that AST shape, too.

Lesson from optional chaining: The earlier we begin to work on consensual AST shape, the less the friction we introduced to the communities.

Context: babel/babel#12282

Line break between method name and parenthesis breaks plugin

This works:

const {Parser} = require('acorn');

Parser.parse(`
class X { 
    x
    () {} 
}`);

This fails:

const {Parser} = require('acorn');
const classFields = require('acorn-class-fields');
Parser.extend(classFields).parse(`
class X { 
    x
    () {} 
}`);

with Unexpected token (4:4).

Losing `this` reference from arrow functions with acorn + Rollup

class X {
  arrFn = () => {
    return this.#privateField; // any this references here, private field is just an example
  };
  #privateField = 42;
}

const fn = new X().arrFn;

fn() // expected: 42

Actual result is an error:

The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten