[GR-74263] Implement Joint Iteration Proposal

[woess]

TL;DR

Implement the TC39 Joint Iteration proposal (stage 3) in GraalJS.

Proposal: https://github.com/tc39/proposal-joint-iteration
Spec draft: https://tc39.es/proposal-joint-iteration/

Details

This proposal adds two new APIs:

• Iterator.zip(iterables[, options])
• Iterator.zipKeyed(iterablesByKey[, options])

These APIs advance multiple iterators in lockstep and produce:

• arrays for Iterator.zip
• objects for Iterator.zipKeyed

The options bag supports:

• mode: "shortest" (default)
• mode: "longest"
• mode: "strict"

For "longest", padding values can be provided:

• as an iterable for Iterator.zip
• as an object for Iterator.zipKeyed

Example:

Iterator.zip([
  [0, 1, 2],
  [3, 4, 5],
]).toArray();
// => [[0, 3], [1, 4], [2, 5]]

Iterator.zipKeyed({
  a: [0, 1, 2],
  b: [3, 4, 5, 6],
  c: [7, 8, 9],
}, {
  mode: "longest",
  padding: { c: 10 },
}).toArray();
// => [
//      { a: 0,         b: 3, c: 7 },
//      { a: 1,         b: 4, c: 8 },
//      { a: 2,         b: 5, c: 9 },
//      { a: undefined, b: 6, c: 10 },
//    ]