nushell/crates/nu-cli/src
JT 2c3aade057
Add pattern matching (#8590)
# Description

This adds `match` and basic pattern matching.

An example:

```
match $x {
  1..10 => { print "Value is between 1 and 10" }
  { foo: $bar } => { print $"Value has a 'foo' field with value ($bar)" }
  [$a, $b] => { print $"Value is a list with two items: ($a) and ($b)" }
  _ => { print "Value is none of the above" }
}
```

Like the recent changes to `if` to allow it to be used as an expression,
`match` can also be used as an expression. This allows you to assign the
result to a variable, eg) `let xyz = match ...`

I've also included a short-hand pattern for matching records, as I think
it might help when doing a lot of record patterns: `{$foo}` which is
equivalent to `{foo: $foo}`.

There are still missing components, so consider this the first step in
full pattern matching support. Currently missing:
* Patterns for strings
* Or-patterns (like the `|` in Rust)
* Patterns for tables (unclear how we want to match a table, so it'll
need some design)
* Patterns for binary values
* And much more

# User-Facing Changes

[see above]

# Tests + Formatting

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
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

> **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
> ```

# After Submitting

If your PR had any user-facing changes, update [the
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.
2023-03-24 14:52:01 +13:00
..
completions Revert "Allow NU_LIBS_DIR and friends to be const" (#8501) 2023-03-17 09:33:24 -05:00
menus Use variable names directly in the format strings (#7906) 2023-01-29 19:37:54 -06:00
commands.rs feat: add a command_not_found hook (#8314) 2023-03-20 17:05:22 +13:00
config_files.rs feat: add a command_not_found hook (#8314) 2023-03-20 17:05:22 +13:00
eval_file.rs feat: add a command_not_found hook (#8314) 2023-03-20 17:05:22 +13:00
lib.rs feat: add a command_not_found hook (#8314) 2023-03-20 17:05:22 +13:00
nu_highlight.rs Box ShellError in Value::Error (#8375) 2023-03-12 09:57:27 +01:00
print.rs print pipeline contents in print (#8305) 2023-03-04 11:31:01 +13:00
prompt_update.rs feat: add a command_not_found hook (#8314) 2023-03-20 17:05:22 +13:00
prompt.rs Make the default prompt play nice with basic fonts (#8080) 2023-03-02 13:59:32 +13:00
reedline_config.rs fixes the ability to have multiple modifiers on keybindings (#8579) 2023-03-23 07:07:14 -05:00
repl.rs fix: set repl_buffer_state to the REPL buffer after the `pre_execut… (#8560) 2023-03-22 06:43:25 -05:00
syntax_highlight.rs Add pattern matching (#8590) 2023-03-24 14:52:01 +13:00
util.rs feat: add a command_not_found hook (#8314) 2023-03-20 17:05:22 +13:00
validation.rs Remove engine_state clones in REPL eval (#7713) 2023-01-10 17:22:32 -08:00