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use nu_engine::CallExt;
use nu_protocol::ast::{Call, RangeInclusion};
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
SyntaxShape, Type, Value,
};
#[derive(Clone)]
pub struct Range;
impl Command for Range {
fn name(&self) -> &str {
"range"
}
fn signature(&self) -> Signature {
Signature::build("range")
.input_output_types(vec![(
Type::List(Box::new(Type::Any)),
Type::List(Box::new(Type::Any)),
)])
.required(
"rows",
SyntaxShape::Range,
"range of rows to return: Eg) 4..7 (=> from 4 to 7)",
)
.category(Category::Filters)
}
fn usage(&self) -> &str {
"Return only the selected rows."
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
example: "[0,1,2,3,4,5] | range 4..5",
description: "Get the last 2 items",
result: Some(Value::List {
vals: vec![Value::test_int(4), Value::test_int(5)],
span: Span::test_data(),
}),
},
Example {
example: "[0,1,2,3,4,5] | range (-2)..",
description: "Get the last 2 items",
result: Some(Value::List {
vals: vec![Value::test_int(4), Value::test_int(5)],
span: Span::test_data(),
}),
},
Example {
example: "[0,1,2,3,4,5] | range (-3)..-2",
description: "Get the next to last 2 items",
result: Some(Value::List {
vals: vec![Value::test_int(3), Value::test_int(4)],
span: Span::test_data(),
}),
},
]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let metadata = input.metadata();
let rows: nu_protocol::Range = call.req(engine_state, stack, 0)?;
let rows_from = get_range_val(rows.from);
let rows_to = if rows.inclusion == RangeInclusion::RightExclusive {
get_range_val(rows.to) - 1
} else {
get_range_val(rows.to)
};
if rows_from < 0 || rows_to < 0 {
let v: Vec<_> = input.into_iter().collect();
let vlen: i64 = v.len() as i64;
let from = if rows_from < 0 {
(vlen + rows_from) as usize
} else {
rows_from as usize
};
let to = if rows_to < 0 {
(vlen + rows_to) as usize
} else if rows_to > v.len() as i64 {
v.len()
} else {
rows_to as usize
};
if from > to {
Ok(PipelineData::Value(
Value::Nothing { span: call.head },
None,
))
} else {
let iter = v.into_iter().skip(from).take(to - from + 1);
Ok(iter.into_pipeline_data(engine_state.ctrlc.clone()))
}
} else {
let from = rows_from as usize;
let to = rows_to as usize;
if from > to {
Ok(PipelineData::Value(
Value::Nothing { span: call.head },
None,
))
} else {
let iter = input.into_iter().skip(from).take(to - from + 1);
Ok(iter.into_pipeline_data(engine_state.ctrlc.clone()))
}
}
.map(|x| x.set_metadata(metadata))
}
}
fn get_range_val(rows_val: Value) -> i64 {
match rows_val {
Value::Int { val: x, .. } => x,
_ => 0,
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(Range {})
}
}