forked from extern/nushell
85 lines
2.1 KiB
Rust
85 lines
2.1 KiB
Rust
use crate::commands::WholeStreamCommand;
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use crate::context::CommandRegistry;
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use crate::prelude::*;
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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 Keep;
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#[derive(Deserialize)]
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pub struct KeepArgs {
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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 Keep {
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fn name(&self) -> &str {
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"keep"
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}
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fn signature(&self) -> Signature {
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Signature::build("keep").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 keep",
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)
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}
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fn usage(&self) -> &str {
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"Keep the number of rows only"
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}
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async fn run(
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&self,
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args: CommandArgs,
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registry: &CommandRegistry,
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) -> Result<OutputStream, ShellError> {
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keep(args, registry).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: "Keep the first row",
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example: "echo [1 2 3] | keep",
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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: "Keep the first four rows",
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example: "echo [1 2 3 4 5] | keep 4",
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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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UntaggedValue::int(3).into(),
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UntaggedValue::int(4).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 keep(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
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let registry = registry.clone();
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let (KeepArgs { rows }, input) = args.process(®istry).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::Keep;
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#[test]
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fn examples_work_as_expected() {
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use crate::examples::test as test_examples;
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test_examples(Keep {})
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}
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}
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