nushell/crates/nu-std/tests/test_std-rfc_iter.nu
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

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use std/assert
use std/testing *
use std-rfc/iter *
@test
def recurse-example-basic [] {
let out = {
"foo": {
"egg": "X"
"spam": "Y"
}
"bar": {
"quox": ["A" "B"]
}
}
| recurse
let expected = [
[path, item];
[ ($.), {foo: {egg: X, spam: Y}, bar: {quox: [A, B]}} ],
[ ($.foo), {egg: X, spam: Y} ],
[ ($.bar), {quox: [A, B]} ],
[ ($.foo.egg), X ],
[ ($.foo.spam), Y ],
[ ($.bar.quox), [A, B] ],
[ ($.bar.quox.0), A ],
[ ($.bar.quox.1), B ]
]
assert equal $out $expected
}
@test
def recurse-example-jq [] {
let out = {"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
let expected = [/, /bin, /home, /bin/ls, /bin/sh, /home/stephen, /home/stephen/jq]
assert equal $out $expected
}
@test
def recurse-example-jq-depth-first [] {
let out = {"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
let expected = [/, /bin, /bin/ls, /bin/sh, /home, /home/stephen, /home/stephen/jq]
assert equal $out $expected
}
@test
def recurse-example-closure [] {
let out = 2
| recurse { ({path: square item: ($in * $in)}) }
| take while { $in.item < 100 }
let expected = [
[path, item];
[$., 2],
[$.square, 4],
[$.square.square, 16]
]
assert equal $out $expected
}