ac578b8491
* Begin allowing comments and multiline scripts. * clippy * Finish moving to groups. Test pass * Keep going * WIP * WIP * BROKEN WIP * WIP * WIP * Fix more tests * WIP: alias starts working * Broken WIP * Broken WIP * Variables begin to work * captures start working * A little better but needs fixed scope * Shorthand env setting * Update main merge * Broken WIP * WIP * custom command parsing * Custom commands start working * Fix coloring and parsing of block * Almost there * Add some tests * Add more param types * Bump version * Fix benchmark * Fix stuff
102 lines
2.5 KiB
Rust
102 lines
2.5 KiB
Rust
use crate::commands::WholeStreamCommand;
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use crate::prelude::*;
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use nu_errors::ShellError;
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use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, Value};
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use nu_source::Tagged;
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#[derive(Deserialize)]
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struct NthArgs {
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row_number: Tagged<u64>,
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rest: Vec<Tagged<u64>>,
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}
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pub struct Nth;
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#[async_trait]
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impl WholeStreamCommand for Nth {
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fn name(&self) -> &str {
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"nth"
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}
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fn signature(&self) -> Signature {
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Signature::build("nth")
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.required(
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"row number",
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SyntaxShape::Int,
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"the number of the row to return",
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)
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.rest(SyntaxShape::Any, "Optionally return more rows")
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}
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fn usage(&self) -> &str {
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"Return only the selected rows"
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}
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async fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
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nth(args).await
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}
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fn examples(&self) -> Vec<Example> {
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vec![
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Example {
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description: "Get the second row",
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example: "echo [first second third] | nth 1",
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result: Some(vec![Value::from("second")]),
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},
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Example {
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description: "Get the first and third rows",
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example: "echo [first second third] | nth 0 2",
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result: Some(vec![Value::from("first"), Value::from("third")]),
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},
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]
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}
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}
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async fn nth(args: CommandArgs) -> Result<OutputStream, ShellError> {
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let (
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NthArgs {
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row_number,
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rest: and_rows,
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},
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input,
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) = args.process().await?;
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let row_numbers = vec![vec![row_number], and_rows]
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.into_iter()
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.flatten()
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.map(|x| x.item)
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.collect::<Vec<u64>>();
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let max_row_number = row_numbers
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.iter()
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.max()
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.expect("Internal error: should be > 0 row numbers");
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Ok(input
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.take(*max_row_number as usize + 1)
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.enumerate()
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.filter_map(move |(idx, item)| {
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futures::future::ready(
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if row_numbers.iter().any(|requested| *requested == idx as u64) {
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Some(ReturnSuccess::value(item))
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} else {
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None
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},
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)
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})
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.to_output_stream())
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}
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#[cfg(test)]
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mod tests {
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use super::Nth;
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use super::ShellError;
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#[test]
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fn examples_work_as_expected() -> Result<(), ShellError> {
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use crate::examples::test as test_examples;
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Ok(test_examples(Nth {})?)
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}
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}
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