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Add --skip flag to nth command (#2953)

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clippy & rustfmt included
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Jakub Žádník 2021-01-20 19:37:30 +02:00 committed by GitHub
parent b435075e09
commit 05e42381df
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1 changed files with 14 additions and 14 deletions
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28
crates/nu-command/src/commands/nth.rs
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@ -8,6 +8,7 @@ use nu_source::Tagged;
struct NthArgs {
row_number: Tagged<u64>,
rest: Vec<Tagged<u64>>,
skip: bool,
}
pub struct Nth;
@ -26,10 +27,11 @@ impl WholeStreamCommand for Nth {
"the number of the row to return",
)
.rest(SyntaxShape::Any, "Optionally return more rows")
.switch("skip", "Skip the rows instead of selecting them", Some('s'))
}
fn usage(&self) -> &str {
"Return only the selected rows"
"Return or skip only the selected rows"
}
async fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
@ -48,6 +50,11 @@ impl WholeStreamCommand for Nth {
example: "echo [first second third] | nth 0 2",
result: Some(vec![Value::from("first"), Value::from("third")]),
},
Example {
description: "Skip the first and third rows",
example: "echo [first second third] | nth --skip 0 2",
result: Some(vec![Value::from("second")]),
},
]
}
}
@ -57,6 +64,7 @@ async fn nth(args: CommandArgs) -> Result<OutputStream, ShellError> {
NthArgs {
row_number,
rest: and_rows,
skip,
},
input,
) = args.process().await?;
@ -67,22 +75,14 @@ async fn nth(args: CommandArgs) -> Result<OutputStream, ShellError> {
.map(|x| x.item)
.collect::<Vec<u64>>();
let max_row_number = row_numbers
.iter()
.max()
.expect("Internal error: should be > 0 row numbers");
Ok(input
.take(*max_row_number as usize + 1)
.enumerate()
.filter_map(move |(idx, item)| {
futures::future::ready(
if row_numbers.iter().any(|requested| *requested == idx as u64) {
Some(ReturnSuccess::value(item))
} else {
None
},
)
futures::future::ready(if row_numbers.contains(&(idx as u64)) ^ skip {
Some(ReturnSuccess::value(item))
} else {
None
})
})
.to_output_stream())
}