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use nu_engine::{eval_block_with_early_return, CallExt};
use nu_protocol::ast::Call;
use nu_protocol::engine::{Closure, Command, EngineState, Stack};
use nu_protocol::{
Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, Signature,
Span, SyntaxShape, Type, Value,
};
#[derive(Clone)]
pub struct EachWhile;
impl Command for EachWhile {
fn name(&self) -> &str {
"each while"
}
fn usage(&self) -> &str {
"Run a block on each row of the input list until a null is found, then create a new list with the results."
}
fn search_terms(&self) -> Vec<&str> {
vec!["for", "loop", "iterate"]
}
fn signature(&self) -> nu_protocol::Signature {
Signature::build(self.name())
.input_output_types(vec![(
Type::List(Box::new(Type::Any)),
Type::List(Box::new(Type::Any)),
)])
.required(
"closure",
SyntaxShape::Closure(Some(vec![SyntaxShape::Any, SyntaxShape::Int])),
"the closure to run",
)
.switch(
"numbered",
"iterate with an index (deprecated; use a two-parameter closure instead)",
Some('n'),
)
.category(Category::Filters)
}
fn examples(&self) -> Vec<Example> {
let stream_test_1 = vec![Value::test_int(2), Value::test_int(4)];
let stream_test_2 = vec![
Value::test_string("Output: 1"),
Value::test_string("Output: 2"),
];
vec![
Example {
example: "[1 2 3 2 1] | each while {|e| if $e < 3 { $e * 2 } }",
description: "Produces a list of each element before the 3, doubled",
result: Some(Value::List {
vals: stream_test_1,
span: Span::test_data(),
}),
},
Example {
example: r#"[1 2 stop 3 4] | each while {|e| if $e != 'stop' { $"Output: ($e)" } }"#,
description: "Output elements until reaching 'stop'",
result: Some(Value::List {
vals: stream_test_2,
span: Span::test_data(),
}),
},
Example {
example: r#"[1 2 3] | each while {|el ind| if $el < 2 { $"value ($el) at ($ind)!"} }"#,
description: "Iterate over each element, printing the matching value and its index",
result: Some(Value::List {
vals: vec![Value::test_string("value 1 at 0!")],
span: Span::test_data(),
}),
},
]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
let capture_block: Closure = call.req(engine_state, stack, 0)?;
let numbered = call.has_flag("numbered");
let metadata = input.metadata();
let ctrlc = engine_state.ctrlc.clone();
let engine_state = engine_state.clone();
let block = engine_state.get_block(capture_block.block_id).clone();
let mut stack = stack.captures_to_stack(&capture_block.captures);
let orig_env_vars = stack.env_vars.clone();
let orig_env_hidden = stack.env_hidden.clone();
let span = call.head;
let redirect_stdout = call.redirect_stdout;
let redirect_stderr = call.redirect_stderr;
match input {
PipelineData::Empty => Ok(PipelineData::Empty),
PipelineData::Value(Value::Range { .. }, ..)
| PipelineData::Value(Value::List { .. }, ..)
| PipelineData::ListStream { .. } => Ok(input
// To enumerate over the input (for the index argument),
// it must be converted into an iterator using into_iter().
// TODO: Could this be changed to .into_interruptible_iter(ctrlc) ?
.into_iter()
.enumerate()
.map_while(move |(idx, x)| {
// with_env() is used here to ensure that each iteration uses
// a different set of environment variables.
// Hence, a 'cd' in the first loop won't affect the next loop.
stack.with_env(&orig_env_vars, &orig_env_hidden);
if let Some(var) = block.signature.get_positional(0) {
if let Some(var_id) = &var.var_id {
if numbered {
stack.add_var(
*var_id,
Value::Record {
cols: vec!["index".into(), "item".into()],
vals: vec![
Value::Int {
val: idx as i64,
span,
},
x.clone(),
],
span,
},
);
} else {
stack.add_var(*var_id, x.clone());
}
}
}
// Optional second index argument
if let Some(var) = block.signature.get_positional(1) {
if let Some(var_id) = &var.var_id {
stack.add_var(
*var_id,
Value::Int {
val: idx as i64,
span,
},
);
}
}
match eval_block_with_early_return(
&engine_state,
&mut stack,
&block,
x.into_pipeline_data(),
redirect_stdout,
redirect_stderr,
) {
Ok(v) => {
let value = v.into_value(span);
if value.is_nothing() {
None
} else {
Some(value)
}
}
Err(_) => None,
}
})
.fuse()
.into_pipeline_data(ctrlc)),
PipelineData::ExternalStream { stdout: None, .. } => Ok(PipelineData::empty()),
PipelineData::ExternalStream {
stdout: Some(stream),
..
} => Ok(stream
.into_iter()
.enumerate()
.map_while(move |(idx, x)| {
// with_env() is used here to ensure that each iteration uses
// a different set of environment variables.
// Hence, a 'cd' in the first loop won't affect the next loop.
stack.with_env(&orig_env_vars, &orig_env_hidden);
let x = match x {
Ok(x) => x,
Err(_) => return None,
};
if let Some(var) = block.signature.get_positional(0) {
if let Some(var_id) = &var.var_id {
if numbered {
stack.add_var(
*var_id,
Value::Record {
cols: vec!["index".into(), "item".into()],
vals: vec![
Value::Int {
val: idx as i64,
span,
},
x.clone(),
],
span,
},
);
} else {
stack.add_var(*var_id, x.clone());
}
}
}
match eval_block_with_early_return(
&engine_state,
&mut stack,
&block,
x.into_pipeline_data(),
redirect_stdout,
redirect_stderr,
) {
Ok(v) => {
let value = v.into_value(span);
if value.is_nothing() {
None
} else {
Some(value)
}
}
Err(_) => None,
}
})
.fuse()
.into_pipeline_data(ctrlc)),
// This match allows non-iterables to be accepted,
// which is currently considered undesirable (Nov 2022).
PipelineData::Value(x, ..) => {
if let Some(var) = block.signature.get_positional(0) {
if let Some(var_id) = &var.var_id {
stack.add_var(*var_id, x.clone());
}
}
eval_block_with_early_return(
&engine_state,
&mut stack,
&block,
x.into_pipeline_data(),
redirect_stdout,
redirect_stderr,
)
}
}
.map(|x| x.set_metadata(metadata))
}
}
#[cfg(test)]
mod test {
use super::*;
use nu_test_support::{nu, pipeline};
#[test]
fn uses_optional_index_argument() {
let actual = nu!(
cwd: ".", pipeline(
r#"[7 8 9 10] | each while {|el ind| $el + $ind } | to nuon"#
));
assert_eq!(actual.out, "[7, 9, 11, 13]");
}
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(EachWhile {})
}
}