nushell/src/commands/first.rs
Jonathan Turner aadacc2d36 Merge master
2019-08-09 16:51:21 +12:00

35 lines
877 B
Rust

use crate::errors::ShellError;
use crate::parser::CommandRegistry;
use crate::prelude::*;
// TODO: "Amount remaining" wrapper
pub fn first(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
let args = args.evaluate_once(registry)?;
if args.len() == 0 {
return Err(ShellError::labeled_error(
"First requires an amount",
"needs parameter",
args.name_span(),
));
}
let amount = args.expect_nth(0)?.as_i64();
let amount = match amount {
Ok(o) => o,
Err(_) => {
return Err(ShellError::labeled_error(
"Value is not a number",
"expected integer",
args.expect_nth(0)?.span(),
))
}
};
Ok(OutputStream::from_input(
args.input.values.take(amount as u64),
))
}