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Make RegExp#[Symbol.*] methods call exec #411

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merged 5 commits into from
Aug 30, 2018

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nicolo-ribaudo
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@zloirock
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Sorry, some more days I'll be unavailable. I'll review it later.

// 21.2.5.8 RegExp.prototype[@@replace](string, replaceValue)
// 21.2.5.11 RegExp.prototype[@@split](string, limit)
? function (string, arg) { return regexMethod.call(string, this, arg); }
// 21.2.5.6 RegExp.prototype[@@match](string)
// 21.2.5.9 RegExp.prototype[@@search](string)
: function (string) { return regexMethod.call(string, this); }
);
// TODO: This line makes the tests fail:
// ReferenceError: Can't find variable: Reflect
// hide(RegExp.prototype[SYMBOL], 'name', '[Symbol.' + KEY + ']');
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In many engines, functions .name property non-writable non-configurable, so, I think, it would be better just remove it.

},
// `RegExp.prototype[@@match]` method
// https://tc39.github.io/ecma262/#sec-regexp.prototype-@@match
function Symbol$match(regexp) {
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For better compression, use named functions only when they should have the same explicit .name property (like match above).

};
try {
return run(assert);
} finally {
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IIRC in very old IE try / finally does not work without catch.

@@ -0,0 +1,5 @@
'use strict';
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Please, add a comment that it's AdvanceStringIndex abstract operation and the link to the spec.

@@ -16,13 +16,17 @@ module.exports = function (KEY, length, exec) {
return ''[KEY](O) != 7;
})) {
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Are you sure that this test also covers all engines without internal execution of .exec method? Maybe makes sense extend it?

var A = [];
var n = 0;
var result;
while ((result = rx.exec(S)) !== null) {
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@zloirock zloirock Jun 30, 2018

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In RegExpExec, own .exec should be called only if it's callable. Maybe makes sense to implement RegExpExec abstract operation?

var execCalled = false;
var re = /a/;
re.exec = function () { execCalled = true; return null; };
return re[SYMBOL] && (re[SYMBOL](''), execCalled);
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It should return a negative result for the existent feature. Use, for example,

re[SYMBOL]('');
return !execCalled;

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Isn't it faster if it avoid throwing an error?

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It's just an example. The main idea of the comment - the result should be inverted.

var O = {};
O[SYMBOL] = function () { return 7; };
return ''[KEY](O) != 7;
}) || fails(function () {
// Symbol-named RegExp methods call .exec
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This test throws an uncaught stack overflow error in the promises tests and I'm not sure why.

@nicolo-ribaudo
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@zloirock I manages to make the tests pass. Could you review this PR again?

@DmitrySoshnikov
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Hey guys, is this PR good to go yet? Is there still anything blocking?

@nicolo-ribaudo
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@zloirock Since Babel uses core-js@2, can I backport this PR?

@zloirock
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@nicolo-ribaudo feel free to add the same PR to v2 branch and I'll publish a new core-js@2 version. But let's land this PR at first.

@zloirock
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I'll review it today or tomorrow. Could you rebase it?

@zloirock
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At first sight, LGTM.

@zloirock zloirock merged commit 6addfef into zloirock:master Aug 30, 2018
@nicolo-ribaudo nicolo-ribaudo deleted the regexp-es2015 branch August 30, 2018 12:35
@zloirock
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@nicolo-ribaudo RegExp#@@replace correctly handles substitutions tests fails in many browsers - for example, in modern FF. Could you fix it?

@zloirock
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zloirock commented Sep 25, 2018 via email

@zloirock
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@nicolo-ribaudo
Chrome 51:
image
Chrome 50:
image
image

@nicolo-ribaudo
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I will fix it later.
Just for curiosity, do you have multiple versions of chrome installed on the same machine?

@zloirock
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I use Saucelabs and run tests in all available browsers before releases.

@zloirock
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zloirock commented Sep 27, 2018

IE8:
image
Safari 9:
image

@nicolo-ribaudo
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nicolo-ribaudo commented Nov 9, 2018

I'm working on this now.

EDIT: Ok, I'm downloading windows, ie8, chrome 50 and chrome 51. Hopefully I will be able to debug the issue 😆

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nicolo-ribaudo commented Nov 11, 2018

@nicolo-ribaudo RegExp#@@replace correctly handles substitutions tests fails in many browsers - for example, in modern FF. Could you fix it?

Which firefox version? I can't reproduce it.


I'm writing down some notes for myself

  • The tests are failing on IE8 because this code:

    var re = /a/;
    re.exec("a");
    re.lastIndex;

    Should evaluate to 0 (it works in Chrome) but evaluates to 1 in IE8.

    Another reason:

    /^(?:(.)?(.)?)/g.exec(".")[2];

    should be undefined but returns "".

  • The tests are failing on Chrome 51 because native split doesn't work with patched
    RegExp#exec: these two snippets should produce the same output but they don't.

    "ab".split(/a*?/);
    
    > ["a", "b"]
    var exec = RegExp.prototype.exec;
    RegExp.prototype.exec = function () { return exec.apply(this, arguments); };
    "ab".split(/a*?/);
    
    > ["ab"]
  • The tests are failing on Chrome 50 because the polyfilled RegExp#@@match,
    since .exec hasn't been modified, calls String#match assuming that it
    won't call RegExp#@@match again (this assumption is wrong).

  • Safari - TODO

Conclusion: I also need to polyfill .exec 🤦‍♂️

@zloirock
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@nicolo-ribaudo

Which firefox version? I can't reproduce it.

IIRC it was fixed in #434

@nicolo-ribaudo
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nicolo-ribaudo commented Nov 12, 2018

@zloirock In order to fix some IE8 failing tests, I need to fix this IE bug:

> /^(a?)/.exec("")
["", ""] // correct

> /^(a)?/.exec("")
> ["", ""] // wrong, should be ["", undefined]

I don't think that it is possible, unless we re-implement the regexp engine. Could I disable an assertion on IE8?

PS. For now I got it working in Chrome 50 & 51 and I'm trying to install Safari in a VM.


EDIT: Fixing the IE bug is possible

@zloirock
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zloirock commented Dec 4, 2018

Available in core-js@3.0.0-beta.4.

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