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group.rs
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group.rs
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use nu_engine::CallExt;
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
Spanned, SyntaxShape, Type, Value,
};
#[derive(Clone)]
pub struct Group;
impl Command for Group {
fn name(&self) -> &str {
"group"
}
fn signature(&self) -> Signature {
Signature::build("group")
// TODO: It accepts Table also, but currently there is no Table
// example. Perhaps Table should be a subtype of List, in which case
// the current signature would suffice even when a Table example
// exists.
.input_output_types(vec![(
Type::List(Box::new(Type::Any)),
Type::List(Box::new(Type::List(Box::new(Type::Any)))),
)])
.required("group_size", SyntaxShape::Int, "the size of each group")
.category(Category::Filters)
}
fn usage(&self) -> &str {
"Groups input into groups of `group_size`."
}
fn examples(&self) -> Vec<Example> {
let stream_test_1 = vec![
Value::list(
vec![Value::test_int(1), Value::test_int(2)],
Span::test_data(),
),
Value::list(
vec![Value::test_int(3), Value::test_int(4)],
Span::test_data(),
),
];
vec![Example {
example: "[1 2 3 4] | group 2",
description: "Group the a list by pairs",
result: Some(Value::list(stream_test_1, Span::test_data())),
}]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let group_size: Spanned<usize> = call.req(engine_state, stack, 0)?;
let ctrlc = engine_state.ctrlc.clone();
let metadata = input.metadata();
//FIXME: add in support for external redirection when engine-q supports it generally
let each_group_iterator = EachGroupIterator {
group_size: group_size.item,
input: Box::new(input.into_iter()),
span: call.head,
};
Ok(each_group_iterator.into_pipeline_data_with_metadata(metadata, ctrlc))
}
}
struct EachGroupIterator {
group_size: usize,
input: Box<dyn Iterator<Item = Value> + Send>,
span: Span,
}
impl Iterator for EachGroupIterator {
type Item = Value;
fn next(&mut self) -> Option<Self::Item> {
let mut group = vec![];
let mut current_count = 0;
loop {
let item = self.input.next();
match item {
Some(v) => {
group.push(v);
current_count += 1;
if current_count >= self.group_size {
break;
}
}
None => break,
}
}
if group.is_empty() {
return None;
}
Some(Value::list(group, self.span))
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(Group {})
}
}