nushell/crates/nu-cmd-lang
Piepmatz 3d5f853b03
Start to Add WASM Support Again (#14418)
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# Description
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The [nushell/demo](https://github.com/nushell/demo) project successfully
demonstrated running Nushell in the browser using WASM. However, the
current version of Nushell cannot be easily built for the
`wasm32-unknown-unknown` target, the default for `wasm-bindgen`.

This PR introduces initial support for the `wasm32-unknown-unknown`
target by disabling OS-dependent features such as filesystem access, IO,
and platform/system-specific functionality. This separation is achieved
using a new `os` feature in the following crates:

 - `nu-cmd-lang`
 - `nu-command`
 - `nu-engine`
 - `nu-protocol`

The `os` feature includes all functionality that interacts with an
operating system. It is enabled by default, but can be disabled using
`--no-default-features`. All crates that depend on these core crates now
use `--no-default-features` to allow compilation for WASM.

To demonstrate compatibility, the following script builds all crates
expected to work with WASM. Direct user interaction, running external
commands, working with plugins, and features requiring `openssl` are out
of scope for now due to their complexity or reliance on C libraries,
which are difficult to compile and link in a WASM environment.

```nushell
[ # compatible crates
	"nu-cmd-base",
	"nu-cmd-extra",
	"nu-cmd-lang",
	"nu-color-config",
	"nu-command",
	"nu-derive-value",
	"nu-engine",
	"nu-glob",
	"nu-json",
	"nu-parser",
	"nu-path",
	"nu-pretty-hex",
	"nu-protocol",
	"nu-std",
	"nu-system",
	"nu-table",
	"nu-term-grid",
	"nu-utils",
	"nuon"
] | each {cargo build -p $in --target wasm32-unknown-unknown --no-default-features}
```

## Caveats
This PR has a few caveats:
1. **`miette` and `terminal-size` Dependency Issue**
`miette` depends on `terminal-size`, which uses `rustix` when the target
is not Windows. However, `rustix` requires `std::os::unix`, which is
unavailable in WASM. To address this, I opened a
[PR](https://github.com/eminence/terminal-size/pull/68) for
`terminal-size` to conditionally compile `rustix` only when the target
is Unix. For now, the `Cargo.toml` includes patches to:
    - Use my forked version of `terminal-size`.
- ~~Use an unreleased version of `miette` that depends on
`terminal-size@0.4`.~~

These patches are temporary and can be removed once the upstream changes
are merged and released.

2. **Test Output Adjustments**
Due to the slight bump in the `miette` version, one test required
adjustments to accommodate minor formatting changes in the error output,
such as shifted newlines.

# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->
This shouldn't break anything but allows using some crates for targeting
`wasm32-unknown-unknown` to revive the demo page eventually.

# Tests + Formatting
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- `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
> ```
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- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

I did not add any extra tests, I just checked that compiling works, also
when using the host target but unselecting the `os` feature.

# 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.
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~~Breaking the wasm support can be easily done by adding some `use`s or
by adding a new dependency, we should definitely add some CI that also
at least builds against wasm to make sure that building for it keep
working.~~
I added a job to build wasm.

---------

Co-authored-by: Ian Manske <ian.manske@pm.me>
2024-11-30 07:57:11 -06:00
..
src Start to Add WASM Support Again (#14418) 2024-11-30 07:57:11 -06:00
build.rs Cratification: Break out nu_cmd_lang into a separate crate (#8181) 2023-02-24 09:54:42 -06:00
Cargo.toml Start to Add WASM Support Again (#14418) 2024-11-30 07:57:11 -06:00
LICENSE Fix rest of license year ranges (#8727) 2023-04-04 09:03:29 +12:00
README.md Remove dataframes crate and feature (#12889) 2024-05-20 17:22:08 +00:00

nu-cmd-lang

the base language and command crate of nu

The commands in this crate are the core commands of the nu language. It is also the base crate upon which all other command crates sit on top of including:

  • nu-command
  • nu-cli
  • nu-cmd-extra

As time goes on and the nu language develops further in parallel with nushell we will be adding other command crates to the system.

What does it mean to be a base crate ?

A base crate is one with minimal dependencies in our system so that other developers can come along and use this crate without having a lot of baggage in terms of other crates which will bloat their underlying application.

Background on nu-cmd-lang

This crate was designed to be a small, concise set of tools or commands that serve as the foundation layer of both nu and nushell. These are the core commands needed to have a nice working version of the nu language without all of the support that the other commands provide inside nushell. Prior to the launch of this crate all of our commands were housed in the crate nu-command. Moving forward we would like to slowly break out the commands in nu-command into different crates; the naming and how this will work and where all the commands will be located is a "work in progress" especially now that the standard library is starting to become more popular as a location for commands. As time goes on some of our commands written in rust will be migrated to nu and when this happens they will be moved into the standard library.