use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
#[derive(Clone)]
pub struct SubCommand;
impl Command for SubCommand {
fn name(&self) -> &str {
"math sqrt"
}
fn signature(&self) -> Signature {
Signature::build("math sqrt")
.input_output_types(vec![(Type::Number, Type::Number)])
.vectorizes_over_list(true)
.category(Category::Math)
}
fn usage(&self) -> &str {
"Returns the square root of the input number"
}
fn search_terms(&self) -> Vec<&str> {
vec!["square", "root"]
}
fn run(
&self,
engine_state: &EngineState,
_stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
let head = call.head;
if matches!(input, PipelineData::Empty) {
return Err(ShellError::PipelineEmpty(head));
}
input.map(
move |value| operate(value, head),
engine_state.ctrlc.clone(),
)
}
fn examples(&self) -> Vec<Example> {
vec![Example {
description: "Compute the square root of each number in a list",
example: "[9 16] | math sqrt",
result: Some(Value::List {
vals: vec![Value::test_int(3), Value::test_int(4)],
span: Span::test_data(),
}),
}]
}
}
fn operate(value: Value, head: Span) -> Value {
match value {
Value::Int { val, span } => {
let squared = (val as f64).sqrt();
if squared.is_nan() {
return error_negative_sqrt(head, span);
}
Value::Float { val: squared, span }
}
Value::Float { val, span } => {
let squared = val.sqrt();
if squared.is_nan() {
return error_negative_sqrt(head, span);
}
Value::Float { val: squared, span }
}
Value::Error { .. } => value,
other => Value::Error {
error: ShellError::OnlySupportsThisInputType(
"numeric".into(),
other.get_type().to_string(),
head,
other.expect_span(),
),
},
}
}
fn error_negative_sqrt(head: Span, span: Span) -> Value {
Value::Error {
error: ShellError::UnsupportedInput(
String::from("Can't square root a negative number"),
"value originates from here".into(),
head,
span,
),
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(SubCommand {})
}
}