JSON example: lexer gets hung up for several seconds

[mindplay-dk]

In the playground, open the default "JSON Grammar and CST output" example.

Then paste the following input:

{
    "name" : "Bobby",
    "children ages : [1, 2, 3, 4],
    "partial success": "only one array element lost"
}

⚠ Notice the deliberate omission of the closing quote after children ages.

Lexer appears to get stuck for more than 6 seconds:

I don't know how that's even possible with an input this small - what could it possibly be doing for this long? 🙂

[NaridaL]

What browser are you using?

[mindplay-dk]

Just upgraded from Chrome 99 to Chrome 100, so:

Version 99.0.4844.84 (Official Build) (64-bit)
Version 100.0.4896.75 (Official Build) (64-bit)

Upgrading to Chrome 100 seems to reveal a bit more detail in the Performance report:

It looks like it's hung up on a RegExp?

[mindplay-dk]

Tested in recent versions of Firefox with similar results.

97.0.1 (64-bit)
98.0.2 (64-bit)

[mindplay-dk]

Also note, in Firefox, the "Output" panel comes up blank after trying to parse this. 🤔

[mindplay-dk]

For the record (as you might expect) same issue in Edge.

[NaridaL]

It's odd, I can't reproduce it in firefox or chrome:

chrome Version 99.0.4844.84 (Official Build) (64-bit):

EDIT: NEVERMIND I was pasting in the wrong field..... I indeed get the same thing

[NaridaL]

Yeah the issue is the regex for the StringLiteral. As far as i can tell, the + nested inside the * leads to an explosion of combinations if it isn't found.

Hold on...

[mindplay-dk]

Sorry, I don't know enough regex to say if the PR is right. 😅

[NaridaL]

@mindplay-dk Should be fixed now.

[mindplay-dk]

Confirmed, the issue is gone. Nice work! Thanks. 🙂