New math commands(product, round, sqrt and sum)

crates/nu-command/src/math/sqrt.rs

@@ -0,0 +1,91 @@
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, Value};
+
+#[derive(Clone)]
+pub struct SubCommand;
+
+impl Command for SubCommand {
+    fn name(&self) -> &str {
+        "math sqrt"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("math sqrt")
+    }
+
+    fn usage(&self) -> &str {
+        "Applies the square root function to a list of numbers"
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        _stack: &mut Stack,
+        call: &Call,
+        input: PipelineData,
+    ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+        let head = call.head;
+        input.map(
+            move |value| operate(value, head),
+            engine_state.ctrlc.clone(),
+        )
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Apply the square root function to a list of numbers",
+            example: "[9 16] | math sqrt",
+            result: Some(Value::List {
+                vals: vec![Value::test_int(3), Value::test_int(4)],
+                span: Span::unknown(),
+            }),
+        }]
+    }
+}
+
+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(span);
+            }
+            Value::Float { val: squared, span }
+        }
+        Value::Float { val, span } => {
+            let squared = val.sqrt();
+            if squared.is_nan() {
+                return error_negative_sqrt(span);
+            }
+            Value::Float { val: squared, span }
+        }
+        other => Value::Error {
+            error: ShellError::UnsupportedInput(
+                String::from("Only numerical values are supported"),
+                other.span().unwrap_or(head),
+            ),
+        },
+    }
+}
+
+fn error_negative_sqrt(span: Span) -> Value {
+    Value::Error {
+        error: ShellError::UnsupportedInput(
+            String::from("Can't square root a negative number"),
+            span,
+        ),
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(SubCommand {})
+    }
+}