forked from extern/nushell
d06f457b2a
* 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>
78 lines
1.9 KiB
Rust
78 lines
1.9 KiB
Rust
use crate::prelude::*;
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use nu_engine::WholeStreamCommand;
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use nu_errors::ShellError;
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use nu_protocol::{Signature, SyntaxShape, UntaggedValue};
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use nu_source::Tagged;
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pub struct First;
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#[derive(Deserialize)]
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pub struct FirstArgs {
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rows: Option<Tagged<usize>>,
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}
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#[async_trait]
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impl WholeStreamCommand for First {
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fn name(&self) -> &str {
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"first"
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}
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fn signature(&self) -> Signature {
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Signature::build("first").optional(
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"rows",
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SyntaxShape::Int,
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"starting from the front, the number of rows to return",
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)
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}
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fn usage(&self) -> &str {
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"Show only the first number of rows."
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}
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async fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
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first(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: "Return the first item of a list/table",
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example: "echo [1 2 3] | first",
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result: Some(vec![UntaggedValue::int(1).into()]),
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},
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Example {
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description: "Return the first 2 items of a list/table",
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example: "echo [1 2 3] | first 2",
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result: Some(vec![
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UntaggedValue::int(1).into(),
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UntaggedValue::int(2).into(),
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]),
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},
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]
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}
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}
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async fn first(args: CommandArgs) -> Result<OutputStream, ShellError> {
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let (FirstArgs { rows }, input) = args.process().await?;
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let rows_desired = if let Some(quantity) = rows {
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*quantity
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} else {
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1
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};
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Ok(input.take(rows_desired).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::First;
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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(First {})?)
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}
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}
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