forked from extern/nushell
98 lines
2.5 KiB
Rust
98 lines
2.5 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::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue};
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use nu_source::Tagged;
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pub struct Every;
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#[derive(Deserialize)]
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pub struct EveryArgs {
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stride: Tagged<u64>,
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skip: Tagged<bool>,
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}
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impl WholeStreamCommand for Every {
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fn name(&self) -> &str {
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"every"
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}
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fn signature(&self) -> Signature {
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Signature::build(self.name())
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.required(
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"stride",
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SyntaxShape::Int,
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"how many rows to skip between (and including) each row returned",
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)
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.switch(
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"skip",
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"skip the rows that would be returned, instead of selecting them",
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Some('s'),
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)
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}
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fn usage(&self) -> &str {
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"Show (or skip) every n-th row, starting from the first one."
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}
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fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
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every(args)
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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 every second row",
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example: "echo [1 2 3 4 5] | every 2",
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result: Some(vec![
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UntaggedValue::int(1).into(),
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UntaggedValue::int(3).into(),
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UntaggedValue::int(5).into(),
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]),
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},
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Example {
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description: "Skip every second row",
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example: "echo [1 2 3 4 5] | every 2 --skip",
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result: Some(vec![
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UntaggedValue::int(2).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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fn every(args: CommandArgs) -> Result<OutputStream, ShellError> {
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let (EveryArgs { stride, skip }, input) = args.process()?;
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let stride = stride.item;
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let skip = skip.item;
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Ok(input
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.enumerate()
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.filter_map(move |(i, value)| {
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let stride_desired = if stride < 1 { 1 } else { stride } as usize;
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let should_include = skip == (i % stride_desired != 0);
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if should_include {
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Some(ReturnSuccess::value(value))
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} else {
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None
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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::Every;
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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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test_examples(Every {})
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}
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}
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