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seq.rs
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seq.rs
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use nu_engine::CallExt;
use nu_protocol::{
ast::Call,
engine::{Command, EngineState, Stack},
Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type,
Value,
};
#[derive(Clone)]
pub struct Seq;
impl Command for Seq {
fn name(&self) -> &str {
"seq"
}
fn signature(&self) -> Signature {
Signature::build("seq")
.input_output_types(vec![(Type::Nothing, Type::List(Box::new(Type::Number)))])
.rest("rest", SyntaxShape::Number, "sequence values")
.category(Category::Generators)
}
fn usage(&self) -> &str {
"Output sequences of numbers."
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
_input: PipelineData,
) -> Result<PipelineData, ShellError> {
seq(engine_state, stack, call)
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "sequence 1 to 10",
example: "seq 1 10",
result: Some(Value::List {
vals: vec![
Value::test_int(1),
Value::test_int(2),
Value::test_int(3),
Value::test_int(4),
Value::test_int(5),
Value::test_int(6),
Value::test_int(7),
Value::test_int(8),
Value::test_int(9),
Value::test_int(10),
],
span: Span::test_data(),
}),
},
Example {
description: "sequence 1.0 to 2.0 by 0.1s",
example: "seq 1.0 0.1 2.0",
result: Some(Value::List {
vals: vec![
Value::test_float(1.0000),
Value::test_float(1.1000),
Value::test_float(1.2000),
Value::test_float(1.3000),
Value::test_float(1.4000),
Value::test_float(1.5000),
Value::test_float(1.6000),
Value::test_float(1.7000),
Value::test_float(1.8000),
Value::test_float(1.9000),
Value::test_float(2.0000),
],
span: Span::test_data(),
}),
},
Example {
description: "sequence 1 to 5, then convert to a string with a pipe separator",
example: "seq 1 5 | str join '|'",
result: None,
},
]
}
}
fn seq(
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
) -> Result<PipelineData, ShellError> {
let span = call.head;
let rest_nums: Vec<Spanned<f64>> = call.rest(engine_state, stack, 0)?;
// note that the check for int or float has to occur here. prior, the check would occur after
// everything had been generated; this does not work well with ListStreams.
// As such, the simple test is to check if this errors out: that means there is a float in the
// input, which necessarily means that parts of the output will be floats.
let rest_nums_check: Result<Vec<Spanned<i64>>, ShellError> = call.rest(engine_state, stack, 0);
let contains_decimals = rest_nums_check.is_err();
if rest_nums.is_empty() {
return Err(ShellError::GenericError(
"seq requires some parameters".into(),
"needs parameter".into(),
Some(call.head),
None,
Vec::new(),
));
}
let rest_nums: Vec<f64> = rest_nums.iter().map(|n| n.item).collect();
run_seq(rest_nums, span, contains_decimals, engine_state)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(Seq {})
}
}
pub fn run_seq(
free: Vec<f64>,
span: Span,
contains_decimals: bool,
engine_state: &EngineState,
) -> Result<PipelineData, ShellError> {
let first = free[0];
let step = if free.len() > 2 { free[1] } else { 1.0 };
let last = { free[free.len() - 1] };
if !contains_decimals {
// integers only
Ok(PipelineData::ListStream(
nu_protocol::ListStream {
stream: Box::new(IntSeq {
count: first as i64,
step: step as i64,
last: last as i64,
span,
}),
ctrlc: engine_state.ctrlc.clone(),
},
None,
))
} else {
// floats
Ok(PipelineData::ListStream(
nu_protocol::ListStream {
stream: Box::new(FloatSeq {
first,
step,
last,
index: 0,
span,
}),
ctrlc: engine_state.ctrlc.clone(),
},
None,
))
}
}
struct FloatSeq {
first: f64,
step: f64,
last: f64,
index: isize,
span: Span,
}
impl Iterator for FloatSeq {
type Item = Value;
fn next(&mut self) -> Option<Value> {
let count = self.first + self.index as f64 * self.step;
// Accuracy guaranteed as far as possible; each time, the value is re-evaluated from the
// base arguments
if (count > self.last && self.step >= 0.0) || (count < self.last && self.step <= 0.0) {
return None;
}
self.index += 1;
Some(Value::Float {
val: count,
span: self.span,
})
}
}
struct IntSeq {
count: i64,
step: i64,
last: i64,
span: Span,
}
impl Iterator for IntSeq {
type Item = Value;
fn next(&mut self) -> Option<Value> {
if (self.count > self.last && self.step >= 0) || (self.count < self.last && self.step <= 0)
{
return None;
}
let ret = Some(Value::Int {
val: self.count,
span: self.span,
});
self.count += self.step;
ret
}
}