77 lines
1.8 KiB
Rust
77 lines
1.8 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::{ReturnSuccess, Signature, SyntaxShape};
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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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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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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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args.process(registry, nth)?.run()
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}
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}
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fn nth(
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NthArgs {
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row_number,
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rest: and_rows,
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}: NthArgs,
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RunnableContext { input, .. }: RunnableContext,
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) -> Result<OutputStream, ShellError> {
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let stream = input
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.values
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.enumerate()
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.map(move |(idx, item)| {
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let row_number = vec![row_number.clone()];
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let row_numbers = vec![&row_number, &and_rows]
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.into_iter()
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.flatten()
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.collect::<Vec<&Tagged<u64>>>();
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let mut result = VecDeque::new();
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if row_numbers
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.iter()
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.any(|requested| requested.item == idx as u64)
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{
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result.push_back(ReturnSuccess::value(item));
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}
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futures::stream::iter(result)
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})
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.flatten();
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Ok(stream.to_output_stream())
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}
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