From ea22c319b6a98fefc310c26495c8264989448820 Mon Sep 17 00:00:00 2001
From: Darren Schroeder <343840+fdncred@users.noreply.github.com>
Date: Tue, 30 Jul 2024 08:53:41 -0500
Subject: [PATCH] make `math sqrt` const (#13487)

# Description

Just a quick PR to demonstrate one way to make commands const.
related to https://github.com/nushell/nushell/issues/13482

# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->

# 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` to
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
> ```
-->

# 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.
-->
---
 crates/nu-command/src/math/sqrt.rs | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/crates/nu-command/src/math/sqrt.rs b/crates/nu-command/src/math/sqrt.rs
index a3ab5fbbd8..d20978222c 100644
--- a/crates/nu-command/src/math/sqrt.rs
+++ b/crates/nu-command/src/math/sqrt.rs
@@ -29,6 +29,10 @@ impl Command for SubCommand {
         vec!["square", "root"]
     }
 
+    fn is_const(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,
@@ -44,6 +48,23 @@ impl Command for SubCommand {
         input.map(move |value| operate(value, head), engine_state.signals())
     }
 
+    fn run_const(
+        &self,
+        working_set: &StateWorkingSet,
+        call: &Call,
+        input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        let head = call.head;
+        // This doesn't match explicit nulls
+        if matches!(input, PipelineData::Empty) {
+            return Err(ShellError::PipelineEmpty { dst_span: head });
+        }
+        input.map(
+            move |value| operate(value, head),
+            working_set.permanent().signals(),
+        )
+    }
+
     fn examples(&self) -> Vec<Example> {
         vec![Example {
             description: "Compute the square root of each number in a list",