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 Window;
impl Command for Window {
fn name(&self) -> &str {
"window"
}
fn signature(&self) -> Signature {
Signature::build("window")
.input_output_types(vec![(
Type::List(Box::new(Type::Any)),
Type::List(Box::new(Type::List(Box::new(Type::Any)))),
)])
.required("window_size", SyntaxShape::Int, "The size of each window.")
.named(
"stride",
SyntaxShape::Int,
"the number of rows to slide over between windows",
Some('s'),
)
.switch(
"remainder",
"yield last chunks even if they have fewer elements than size",
Some('r'),
)
.category(Category::Filters)
}
fn usage(&self) -> &str {
"Creates a sliding window of `window_size` that slide by n rows/elements across input."
}
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(2), Value::test_int(3)],
Span::test_data(),
),
Value::list(
vec![Value::test_int(3), Value::test_int(4)],
Span::test_data(),
),
];
let stream_test_2 = vec![
Value::list(
vec![Value::test_int(1), Value::test_int(2)],
Span::test_data(),
),
Value::list(
vec![Value::test_int(4), Value::test_int(5)],
Span::test_data(),
),
Value::list(
vec![Value::test_int(7), Value::test_int(8)],
Span::test_data(),
),
];
let stream_test_3 = vec![
Value::list(
vec![Value::test_int(1), Value::test_int(2), Value::test_int(3)],
Span::test_data(),
),
Value::list(
vec![Value::test_int(4), Value::test_int(5)],
Span::test_data(),
),
];
vec![
Example {
example: "[1 2 3 4] | window 2",
description: "A sliding window of two elements",
result: Some(Value::list(
stream_test_1,
Span::test_data(),
)),
},
Example {
example: "[1, 2, 3, 4, 5, 6, 7, 8] | window 2 --stride 3",
description: "A sliding window of two elements, with a stride of 3",
result: Some(Value::list(
stream_test_2,
Span::test_data(),
)),
},
Example {
example: "[1, 2, 3, 4, 5] | window 3 --stride 3 --remainder",
description: "A sliding window of equal stride that includes remainder. Equivalent to chunking",
result: Some(Value::list(
stream_test_3,
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();
let stride: Option<usize> = call.get_flag(engine_state, stack, "stride")?;
let remainder = call.has_flag(engine_state, stack, "remainder")?;
let stride = stride.unwrap_or(1);
let each_group_iterator = EachWindowIterator {
group_size: group_size.item,
input: Box::new(input.into_iter()),
span: call.head,
previous: None,
stride,
remainder,
};
Ok(each_group_iterator.into_pipeline_data_with_metadata(metadata, ctrlc))
}
}
struct EachWindowIterator {
group_size: usize,
input: Box<dyn Iterator<Item = Value> + Send>,
span: Span,
previous: Option<Vec<Value>>,
stride: usize,
remainder: bool,
}
impl Iterator for EachWindowIterator {
type Item = Value;
fn next(&mut self) -> Option<Self::Item> {
let mut group = self.previous.take().unwrap_or_else(|| {
let mut vec = Vec::new();
vec.try_reserve(self.group_size + self.stride).ok();
vec
});
let mut current_count = 0;
if group.is_empty() {
loop {
let item = self.input.next();
match item {
Some(v) => {
group.push(v);
current_count += 1;
if current_count >= self.group_size {
break;
}
}
None => {
if self.remainder {
break;
} else {
return None;
}
}
}
}
} else {
loop {
let item = self.input.next();
match item {
Some(v) => {
group.push(v);
current_count += 1;
if current_count >= self.stride {
break;
}
}
None => {
if self.remainder {
break;
} else {
return None;
}
}
}
}
group.drain(..self.stride.min(group.len()));
}
if group.is_empty() {
return None;
}
let return_group = group.clone();
self.previous = Some(group);
Some(Value::list(return_group, self.span))
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(Window {})
}
}