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https://github.com/nushell/nushell.git
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Make take work like first (#5942)
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JT
GitHub
parent
2ac5b0480a
commit
c16d8f0d5f
@ -1,11 +1,9 @@
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use std::convert::TryInto;
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use nu_engine::CallExt;
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use nu_protocol::ast::Call;
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use nu_protocol::engine::{Command, EngineState, Stack};
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use nu_protocol::{
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ast::Call,
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engine::{Command, EngineState, Stack},
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Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
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SyntaxShape, Value,
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Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, ShellError,
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Signature, Span, SyntaxShape, Type, Value,
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};
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#[derive(Clone)]
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@ -17,45 +15,17 @@ impl Command for Take {
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}
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fn signature(&self) -> Signature {
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Signature::build(self.name())
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.optional("n", SyntaxShape::Int, "the number of elements to take")
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Signature::build("take")
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.optional(
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"n",
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SyntaxShape::Int,
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"starting from the front, the number of elements to return",
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)
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.category(Category::Filters)
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}
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fn usage(&self) -> &str {
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"Take the first n elements of the input."
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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: "Take two elements",
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example: "echo [[editions]; [2015] [2018] [2021]] | take 2",
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result: Some(Value::List {
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vals: vec![
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Value::Record {
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cols: vec!["editions".to_owned()],
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vals: vec![Value::test_int(2015)],
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span: Span::test_data(),
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},
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Value::Record {
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cols: vec!["editions".to_owned()],
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vals: vec![Value::test_int(2018)],
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span: Span::test_data(),
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},
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],
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span: Span::test_data(),
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}),
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},
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Example {
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description: "Take the first value",
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example: "echo [2 4 6 8] | take",
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result: Some(Value::List {
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vals: vec![Value::test_int(2)],
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span: Span::test_data(),
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}),
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},
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]
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"Take only the first n elements."
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}
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fn run(
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@ -64,38 +34,134 @@ impl Command for Take {
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stack: &mut Stack,
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call: &Call,
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input: PipelineData,
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) -> Result<PipelineData, ShellError> {
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let n: Option<Value> = call.opt(engine_state, stack, 0)?;
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let metadata = input.metadata();
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) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
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first_helper(engine_state, stack, call, input)
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}
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let n: usize = match n {
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Some(Value::Int { val, span }) => val.try_into().map_err(|err| {
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ShellError::UnsupportedInput(
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format!("Could not convert {} to unsigned integer: {}", val, err),
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span,
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)
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})?,
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Some(_) => {
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let span = call.head;
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return Err(ShellError::TypeMismatch("expected integer".into(), span));
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}
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None => 1,
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};
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let ctrlc = engine_state.ctrlc.clone();
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Ok(input
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.into_iter()
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.take(n)
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.into_pipeline_data(ctrlc)
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.set_metadata(metadata))
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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: "[1 2 3] | take",
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result: Some(Value::test_int(1)),
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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: "[1 2 3] | take 2",
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result: Some(Value::List {
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vals: vec![Value::test_int(1), Value::test_int(2)],
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span: Span::test_data(),
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}),
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},
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]
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::Take;
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fn first_helper(
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engine_state: &EngineState,
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stack: &mut Stack,
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call: &Call,
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input: PipelineData,
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) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
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let head = call.head;
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let rows: Option<i64> = call.opt(engine_state, stack, 0)?;
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let mut rows_desired: usize = match rows {
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Some(x) => x as usize,
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None => 1,
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};
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let ctrlc = engine_state.ctrlc.clone();
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let metadata = input.metadata();
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let mut input_peek = input.into_iter().peekable();
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if input_peek.peek().is_some() {
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match input_peek
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.peek()
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.ok_or_else(|| {
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ShellError::GenericError(
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"Error in first".into(),
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"unable to pick on next value".into(),
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Some(call.head),
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None,
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Vec::new(),
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)
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})?
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.get_type()
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{
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Type::Binary => {
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match &mut input_peek.next() {
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Some(v) => match &v {
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Value::Binary { val, .. } => {
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let bytes = val;
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if bytes.len() >= rows_desired {
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// We only want to see a certain amount of the binary
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// so let's grab those parts
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let output_bytes = bytes[0..rows_desired].to_vec();
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Ok(Value::Binary {
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val: output_bytes,
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span: head,
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}
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.into_pipeline_data())
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} else {
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// if we want more rows that the current chunk size (8192)
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// we must gradually get bigger chunks while testing
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// if it's within the requested rows_desired size
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let mut bigger: Vec<u8> = vec![];
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bigger.extend(bytes);
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while bigger.len() < rows_desired {
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match input_peek.next() {
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Some(Value::Binary { val, .. }) => bigger.extend(val),
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_ => {
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// We're at the end of our data so let's break out of this loop
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// and set the rows_desired to the size of our data
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rows_desired = bigger.len();
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break;
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}
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}
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}
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let output_bytes = bigger[0..rows_desired].to_vec();
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Ok(Value::Binary {
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val: output_bytes,
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span: head,
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}
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.into_pipeline_data())
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}
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}
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_ => todo!(),
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},
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None => Ok(input_peek
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.into_iter()
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.take(rows_desired)
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.into_pipeline_data(ctrlc)
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.set_metadata(metadata)),
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}
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}
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_ => {
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if rows_desired == 1 {
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match input_peek.next() {
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Some(val) => Ok(val.into_pipeline_data()),
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None => Err(ShellError::AccessBeyondEndOfStream(head)),
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}
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} else {
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Ok(input_peek
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.into_iter()
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.take(rows_desired)
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.into_pipeline_data(ctrlc)
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.set_metadata(metadata))
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}
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}
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}
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} else {
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Err(ShellError::UnsupportedInput(
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String::from("Cannot perform into string on empty input"),
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head,
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))
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}
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn test_examples() {
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use crate::test_examples;
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