Wildcard lookup operator performance

[theneosloth]

I'm using xee for a CLI that deals with fairly large arrays of nested maps (100+ elements).

One thing I noticed is that wildcard lookups suffer a huge performance degradation when nested. For example, using a map structured like the following (full file generated.json, loaded in through fn:parse-json)

[
  {
    "foo": 0,
    "nested": [{"foo": 0}, {"foo": 1}, {"foo": 2}]
  },
  {
    "foo": 1,
    "nested": [{"foo": 0}, {"foo": 1}, {"foo": 2}]
  },
...
  {
    "foo": 99,
    "nested": [{"foo": 0}, {"foo": 1}, {"foo": 2}]
  }
]

A naive wildcard query ?*nested?*?foo takes ~30 seconds on my machine, while something like a call to map:find(?*?nested, "foo") takes 2 milliseconds. With larger arrays similar lookups take tens of minutes. I tested this out in xquery and basex as well to compare and they don't have a noticeable performance hit

I ran a query through a profiler and as far as I could tell this is due to a large number of allocations made in wildcard_helper and lookup_helper . I am working on a MR to improve the performance and I was wondering if you had an idea on how to approach this

Thank you!