Bahex e7d2717424
feat(std-rfc): add iter module and recurse command (#15840)
# Description
`recurse` command is similar to `jq`'s `recurse`/`..` command. Along
with values, it also returns their cell-paths relative to the "root"
(initial input)

By default it uses breadth-first traversal, collecting child items of
all available sibling items before starting to process those child
items. This means output is ordered in increasing depth.
With the `--depth-first` flag it uses a stack based recursive descend,
which results in output order identical to `jq`'s `recurse`.

It can be used in the following ways:
- `... | recurse`: Recursively traverses the input value, returns each
value it finds as a stream.
- `... | recurse foo.bar`: Only descend through the given cell-path.
- `... | recurse {|parent| ... }`: Produce child values with a closure.

```nushell
{
    "foo": {
        "egg": "X"
        "spam": "Y"
    }
    "bar": {
        "quox": ["A" "B"]
    }
}
| recurse
| update item { to nuon }

# => ╭───┬──────────────┬───────────────────────────────────────────────╮
# => │ # │     path     │                     item                      │
# => ├───┼──────────────┼───────────────────────────────────────────────┤
# => │ 0 │ $.           │ {foo: {egg: X, spam: Y}, bar: {quox: [A, B]}} │
# => │ 1 │ $.foo        │ {egg: X, spam: Y}                             │
# => │ 2 │ $.bar        │ {quox: [A, B]}                                │
# => │ 3 │ $.foo.egg    │ "X"                                           │
# => │ 4 │ $.foo.spam   │ "Y"                                           │
# => │ 5 │ $.bar.quox   │ [A, B]                                        │
# => │ 6 │ $.bar.quox.0 │ "A"                                           │
# => │ 7 │ $.bar.quox.1 │ "B"                                           │
# => ╰───┴──────────────┴───────────────────────────────────────────────╯


{"name": "/", "children": [
    {"name": "/bin", "children": [
        {"name": "/bin/ls", "children": []},
        {"name": "/bin/sh", "children": []}]},
    {"name": "/home", "children": [
        {"name": "/home/stephen", "children": [
            {"name": "/home/stephen/jq", "children": []}]}]}]}
| recurse children
| get item.name

# => ╭───┬──────────────────╮
# => │ 0 │ /                │
# => │ 1 │ /bin             │
# => │ 2 │ /home            │
# => │ 3 │ /bin/ls          │
# => │ 4 │ /bin/sh          │
# => │ 5 │ /home/stephen    │
# => │ 6 │ /home/stephen/jq │
# => ╰───┴──────────────────╯


{"name": "/", "children": [
    {"name": "/bin", "children": [
        {"name": "/bin/ls", "children": []},
        {"name": "/bin/sh", "children": []}]},
    {"name": "/home", "children": [
        {"name": "/home/stephen", "children": [
            {"name": "/home/stephen/jq", "children": []}]}]}]}
| recurse children --depth-first
| get item.name

# => ╭───┬──────────────────╮
# => │ 0 │ /                │
# => │ 1 │ /bin             │
# => │ 2 │ /bin/ls          │
# => │ 3 │ /bin/sh          │
# => │ 4 │ /home            │
# => │ 5 │ /home/stephen    │
# => │ 6 │ /home/stephen/jq │
# => ╰───┴──────────────────╯


2
| recurse { ({path: square item: ($in * $in)}) }
| take while { $in.item < 100 }

# => ╭───┬─────────────────┬──────╮
# => │ # │      path       │ item │
# => ├───┼─────────────────┼──────┤
# => │ 0 │ $.              │    2 │
# => │ 1 │ $.square        │    4 │
# => │ 2 │ $.square.square │   16 │
# => ╰───┴─────────────────┴──────╯
``` 

# User-Facing Changes
No changes other than the new command.

# Tests + Formatting
Added tests for examples. (As we can't run them directly as tests yet.)
- 🟢 `toolkit test stdlib`

# After Submitting
- Update relevant parts of
https://www.nushell.sh/cookbook/jq_v_nushell.html
- `$env.config | recurse | where ($it.item | describe -d).type not-in
[list, record, table]` can partially cover the use case of `config
flatten`, should we do something?

---------

Co-authored-by: Bahex <17417311+Bahex@users.noreply.github.com>
2025-06-03 11:21:12 -04:00
..
2025-05-24 00:54:33 +08:00
2022-02-07 14:54:06 -05:00

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