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# Description
This PR adds the `merge deep` command. This allows you to merge nested
records and tables/lists within records together, instead of overwriting
them. The code for `merge` was reworked to support more general merging
of values, so `merge` and `merge deep` use the same underlying code.
`merge deep` mostly works like `merge`, except it recurses into inner
records which exist in both the input and argument rather than just
overwriting. For lists and by extension tables, `merge deep` has a
couple different strategies for merging inner lists, which can be
selected with the `--strategy` flag. These are:
- `table`: Merges tables element-wise, similarly to the merge command.
Non-table lists are not merged.
- `overwrite`: Lists and tables are overwritten with their corresponding
value from the argument, similarly to scalars.
- `append`: Lists and tables in the input are appended with the
corresponding list from the argument.
- `prepend`: Lists and tables in the input are prepended with the
corresponding list from the argument.
This can also be used with the new config changes to write a monolithic
record of _only_ the config values you want to change:
```nushell
# in config file:
const overrides = {
history: {
file_format: "sqlite",
isolation: true
}
}
# use append strategy for lists, e.g., menus keybindings
$env.config = $env.config | merge deep --strategy=append $overrides
# later, in REPL:
$env.config.history
# => ╭───────────────┬────────╮
# => │ max_size │ 100000 │
# => │ sync_on_enter │ true │
# => │ file_format │ sqlite │
# => │ isolation │ true │
# => ╰───────────────┴────────╯
```
<details>
<summary>Performance details</summary>
For those interested, there was less than one standard deviation of
difference in startup time when setting each config item individually
versus using <code>merge deep</code>, so you can use <code>merge
deep</code> in your config at no measurable performance cost. Here's my
results:
My normal config (in 0.101 style, with each `$env.config.[...]` value
updated individually)
```nushell
bench --pretty { ./nu -l -c '' }
# => 45ms 976µs 983ns +/- 455µs 955ns
```
Equivalent config with a single `overrides` record and `merge deep -s
append`:
```nushell
bench --pretty { ./nu -l -c '' }
# => 45ms 587µs 428ns +/- 702µs 944ns
```
</details>
Huge thanks to @Bahex for designing the strategies API and helping
finish up this PR while I was sick ❤️
Related: #12148
# User-Facing Changes
Adds the `merge deep` command to recursively merge records. For example:
```nushell
{a: {foo: 123 bar: "overwrite me"}, b: [1, 2, 3]} | merge deep {a: {bar: 456, baz: 789}, b: [4, 5, 6]}
# => ╭───┬───────────────╮
# => │ │ ╭─────┬─────╮ │
# => │ a │ │ foo │ 123 │ │
# => │ │ │ bar │ 456 │ │
# => │ │ │ baz │ 789 │ │
# => │ │ ╰─────┴─────╯ │
# => │ │ ╭───┬───╮ │
# => │ b │ │ 0 │ 4 │ │
# => │ │ │ 1 │ 5 │ │
# => │ │ │ 2 │ 6 │ │
# => │ │ ╰───┴───╯ │
# => ╰───┴───────────────╯
```
`merge deep` also has different strategies for merging inner lists and
tables. For example, you can use the `append` strategy to _merge_ the
inner `b` list instead of overwriting it.
```nushell
{a: {foo: 123 bar: "overwrite me"}, b: [1, 2, 3]} | merge deep --strategy=append {a: {bar: 456, baz: 789}, b: [4, 5, 6]}
# => ╭───┬───────────────╮
# => │ │ ╭─────┬─────╮ │
# => │ a │ │ foo │ 123 │ │
# => │ │ │ bar │ 456 │ │
# => │ │ │ baz │ 789 │ │
# => │ │ ╰─────┴─────╯ │
# => │ │ ╭───┬───╮ │
# => │ b │ │ 0 │ 1 │ │
# => │ │ │ 1 │ 2 │ │
# => │ │ │ 2 │ 3 │ │
# => │ │ │ 3 │ 4 │ │
# => │ │ │ 4 │ 5 │ │
# => │ │ │ 5 │ 6 │ │
# => │ │ ╰───┴───╯ │
# => ╰───┴───────────────╯
```
**Note to release notes writers**: Please credit @Bahex for this PR as
well 😄
# Tests + Formatting
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Don't forget to add tests that cover your changes.
Make sure you've run and fixed any issues with these commands:
- `cargo fmt --all -- --check` to check standard code formatting (`cargo
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check that you're using the standard code style
- `cargo test --workspace` to check that all tests pass (on Windows make
sure to [enable developer
mode](https://learn.microsoft.com/en-us/windows/apps/get-started/developer-mode-features-and-debugging))
- `cargo run -- -c "use toolkit.nu; toolkit test stdlib"` to run the
tests for the standard library
> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```
-->
Added tests for deep merge
- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`
# After Submitting
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documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
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N/A
---------
Co-authored-by: Bahex <bahey1999@gmail.com>
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|---|---|---|
| .. | ||
| commands | ||
| format_conversions | ||
| main.rs | ||
| sort_utils.rs | ||