fix: referential equalities DOS

[Skn0tt]

Closes #346

[JeremyMoeglich]

This seems to introduce a regression in the following case.

import superjson from 'superjson';

const circularSet = new Set();
circularSet.add(circularSet);

const json = superjson.stringify(circularSet);
const result = superjson.parse(json);


if (result.has(result)) {
  console.log("✅ Reference preserved");
} else {
    console.error("❌ Reference broken: Set does not contain itself");
    console.log(result);
}

[JeremyMoeglich]

Also found this case that seems to regress

import superjson from 'superjson';

const sharedRegex = /\s+/;

const root = {
  a: sharedRegex,
  b: sharedRegex
};

const json = superjson.stringify(root);
const result = superjson.parse(json);

if (result.a === result.b) {
  console.log("✅ Shared reference preserved");
} else {
  console.error("❌ Shared reference lost: result.a !== result.b");
}

[Skn0tt]

Thanks! I found a fix for the shared regex, will take a look at the circular set after the weekend. If you find a solution i'm all ears!

[Skn0tt]

Managed to fix the circular set, but the diff is becoming more and more unwieldly the more I fix stuff. I'm less convinced of this approach now, but going through the motions seems to be a good way of expanding our test coverage. @JeremyMoeglich if you could try to find some more breakages, that'd be wonderful!

[JeremyMoeglich]

Found this case.

import superjson from 'superjson';

const outer = new Set();
const inner = new Set();

// outer -> inner
outer.add(inner);
// inner -> outer
inner.add(outer);

const json = superjson.stringify(outer);
const result = superjson.parse(json);

const resultInner = result.values().next().value;

if (resultInner instanceof Set && resultInner.has(result)) {
  console.log("✅ Success: Nested circular Set reference preserved");
} else {
  console.error("❌ Mismatch: Reference broken.");
}

[JeremyMoeglich]

Another case

import superjson from 'superjson';

const inner = [/a/];
const root = [inner, inner];

try {
  const json = superjson.stringify(root);
  const _ = superjson.parse(json);
} catch (e) {
  console.error(`❌ threw: ${e}`);
}

[JeremyMoeglich]

Another case:

import superjson from "superjson";

const ta = new Uint8Array(0);
const inner = [ta, ta];
const root = [inner, inner];

const s1 = superjson.stringify(root);
const roundtripped = superjson.parse(s1);
const s2 = superjson.stringify(roundtripped);

if (s1 !== s2) {
  console.error("❌ mismatch: restringified !== stringified");
  console.log(s1);
  console.log(s2);
} else {
  console.log("✅ ok: restringified === stringified");
}