Javascript: migrate prototypical ATN objects to ES6

[carocad]

This PR is a follow up on #2749.

The scope of this PR is to refactor the ATN object declarations to:

• use es6 classes/inheritance instead of direct prototype manipulation. Es6 class declarations are really just syntactic sugar over prototype inheritance so this change should have no effect on the runtime itself.
• refactor exports to directly expose a single class whenever possible
• use const/let on variable declarations to improve variable scoping
• refactor comments to be JsDoc compatible which most IDEs can leverage to provide better developer feedback

NOTE: I also renamed this "constructor" to be the equals method as it made no sense to have two constructors and for consistency with the SemanticContext.java implementation

[ericvergnaud]

Hi,

thanks for this

re "NOTE: I also renamed this "constructor" to be the equals method as it made no sense to have two constructors and for consistency with the SemanticContext.java implementation"
I couldn't find the corresponding change (the link doesn't lead to a specific chunk)

Cheers

[carocad]

@ericvergnaud it seems that github doesnt show the file due to the file being "collapsed" i.e diff too big.

Anyway, here is the actual diff.

Specifically this below:

OR.prototype = Object.create(SemanticContext.prototype);
OR.prototype.constructor = OR;

OR.prototype.constructor = function(other) {
	if (this === other) {
		return true;
	} else if (!(other instanceof OR)) {
		return false;
	} else {
		return this.opnds === other.opnds;

As you can see the code declares the constructor of OR as being the function OR but then it overwrites it with another "constructor" which checks if the two objects are equal.

[ericvergnaud]

it does look like a bug, but then I wonder how the whole thing works...

[ericvergnaud]

maybe we're lacking some tests for semantic predicates

[carocad]

it does look like a bug, but then I wonder how the whole thing works...

a simple

const foo = new OR("a", "b")
console.log(foo)

at the end of the SemanticContext.js file shows that the constructor isnt called when calling new bur rather the "real" constructor is being called. It simply sets the values on the prototype chain. I guess that this was working due to that "misconception" 🤷‍♂

[ericvergnaud]

@parrt blessed

[ericvergnaud]

@carocad if not already done, would you be able to provide a doc for using this ES6 version locally?
I've tried npm link, which ends up badly (ES2015 functions inheriting from ES6 classes...)
I've tried webpack, but that creates a browser only minimized file

[carocad]

would you be able to provide a doc for using this ES6 version locally?

Not sure what you mean. Locally it is simply using node.js so a standard const antlr4 = require('./src/antlr4') would do (assuming that you are in the js runtime dir).

That is also what the test suite does. Generates the code and copies the js runtime locally so that it is available.

I've tried npm link, which ends up badly (ES2015 functions inheriting from ES6 classes...)

mmmm 🤔 . I tried npm link as per the official documentation and it worked as expected. I was able to import the library with const antlr4 = require('antlr4'). Nodejs displays the antlr4 object as containing functions however I think that is normal; as classes are just sugared functions.

I could do an extra guide on how to use it but right now I don't know exactly what to put there as it is simply "require it as you would any other node.js library" 🤷‍♂️

[ericvergnaud]

I suspect the issue I encountered related to using pre ES6 generated parser and lexer with latest ES6 runtime in node I’ll double check, and if the case, we'll need to document that to limit support

…

Le 14 juil. 2020 à 03:16, Camilo Roca ***@***.***> a écrit : would you be able to provide a doc for using this ES6 version locally? Not sure what you mean. Locally it is simply using node.js so a standard const antlr4 = require('./src/antlr4') would do (assuming that you are in the js runtime dir). That is also what the test suite does. Generates the code and copies the js runtime locally so that it is available. I've tried npm link, which ends up badly (ES2015 functions inheriting from ES6 classes...) mmmm 🤔 . I tried npm link as per the official documentation <https://docs.npmjs.com/cli/link> and it worked as expected. I was able to import the library with const antlr4 = require('antlr4'). Nodejs displays the antlr4 object as containing functions however I think that is normal; as classes are just sugared functions. I could do an extra guide on how to use it but right now I don't know exactly what to put there as it is simply "require it as you would any other node.js library" 🤷‍♂️ — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#2771 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAZNQJABLXDH475CMS3R2N3R3NMR7ANCNFSM4LDZSDOA>.