nushell/crates/nu-command/src/commands/last.rs
Michael Angerman d06f457b2a
nu-cli refactor moving commands into their own crate nu-command (#2910)
* move commands, futures.rs, script.rs, utils

* move over maybe_print_errors

* add nu_command crate references to nu_cli

* in commands.rs open up to pub mod from pub(crate)

* nu-cli, nu-command, and nu tests are now passing

* cargo fmt

* clean up nu-cli/src/prelude.rs

* code cleanup

* for some reason lex.rs was not formatted, may be causing my error

* remove mod completion from lib.rs which was not being used along with quickcheck macros

* add in allow unused imports

* comment out one failing external test; comment out one failing internal test

* revert commenting out failing tests; something else might be going on; someone with a windows machine should check and see what is going on with these failing windows tests

* Update Cargo.toml

Extend the optional features to nu-command

Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com>
2021-01-12 17:59:53 +13:00

89 lines
2.2 KiB
Rust

use crate::prelude::*;
use nu_engine::WholeStreamCommand;
use nu_errors::ShellError;
use nu_protocol::{Signature, SyntaxShape, UntaggedValue, Value};
use nu_source::Tagged;
pub struct Last;
#[derive(Deserialize)]
pub struct LastArgs {
rows: Option<Tagged<u64>>,
}
#[async_trait]
impl WholeStreamCommand for Last {
fn name(&self) -> &str {
"last"
}
fn signature(&self) -> Signature {
Signature::build("last").optional(
"rows",
SyntaxShape::Number,
"starting from the back, the number of rows to return",
)
}
fn usage(&self) -> &str {
"Show only the last number of rows."
}
async fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
last(args).await
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Get the last row",
example: "echo [1 2 3] | last",
result: Some(vec![Value::from(UntaggedValue::from(BigInt::from(3)))]),
},
Example {
description: "Get the last three rows",
example: "echo [1 2 3 4 5] | last 3",
result: Some(vec![
UntaggedValue::int(3).into(),
UntaggedValue::int(4).into(),
UntaggedValue::int(5).into(),
]),
},
]
}
}
async fn last(args: CommandArgs) -> Result<OutputStream, ShellError> {
let (LastArgs { rows }, input) = args.process().await?;
let v: Vec<_> = input.into_vec().await;
let end_rows_desired = if let Some(quantity) = rows {
*quantity as usize
} else {
1
};
let beginning_rows_to_skip = if end_rows_desired < v.len() {
v.len() - end_rows_desired
} else {
0
};
let iter = v.into_iter().skip(beginning_rows_to_skip);
Ok(futures::stream::iter(iter).to_output_stream())
}
#[cfg(test)]
mod tests {
use super::Last;
use super::ShellError;
#[test]
fn examples_work_as_expected() -> Result<(), ShellError> {
use crate::examples::test as test_examples;
Ok(test_examples(Last {})?)
}
}