use super::utils::chain_error_with_input;
use nu_engine::{ClosureEval, ClosureEvalOnce, command_prelude::*};
use nu_protocol::engine::Closure;
#[derive(Clone)]
pub struct Each;
impl Command for Each {
fn name(&self) -> &str {
"each"
}
fn description(&self) -> &str {
"Run a closure on each row of the input list, creating a new list with the results."
}
fn extra_description(&self) -> &str {
r#"Since tables are lists of records, passing a table into 'each' will
iterate over each record, not necessarily each cell within it.
Avoid passing single records to this command. Since a record is a
one-row structure, 'each' will only run once, behaving similar to 'do'.
To iterate over a record's values, use 'items' or try converting it to a table
with 'transpose' first."#
}
fn search_terms(&self) -> Vec<&str> {
vec!["for", "loop", "iterate", "map"]
}
fn signature(&self) -> nu_protocol::Signature {
Signature::build("each")
.input_output_types(vec![
(
Type::List(Box::new(Type::Any)),
Type::List(Box::new(Type::Any)),
),
(Type::table(), Type::List(Box::new(Type::Any))),
(Type::Any, Type::Any),
])
.required(
"closure",
SyntaxShape::Closure(Some(vec![SyntaxShape::Any])),
"The closure to run.",
)
.switch("keep-empty", "keep empty result cells", Some('k'))
.allow_variants_without_examples(true)
.category(Category::Filters)
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
example: "[1 2 3] | each {|e| 2 * $e }",
description: "Multiplies elements in the list",
result: Some(Value::test_list(vec![
Value::test_int(2),
Value::test_int(4),
Value::test_int(6),
])),
},
Example {
example: "{major:2, minor:1, patch:4} | values | each {|| into string }",
description: "Produce a list of values in the record, converted to string",
result: Some(Value::test_list(vec![
Value::test_string("2"),
Value::test_string("1"),
Value::test_string("4"),
])),
},
Example {
example: r#"[1 2 3 2] | each {|e| if $e == 2 { "two" } }"#,
description: "'null' items will be dropped from the result list. It has the same effect as 'filter_map' in other languages.",
result: Some(Value::test_list(vec![
Value::test_string("two"),
Value::test_string("two"),
])),
},
Example {
example: r#"[1 2 3] | enumerate | each {|e| if $e.item == 2 { $"found 2 at ($e.index)!"} }"#,
description: "Iterate over each element, producing a list showing indexes of any 2s",
result: Some(Value::test_list(vec![Value::test_string("found 2 at 1!")])),
},
Example {
example: r#"[1 2 3] | each --keep-empty {|e| if $e == 2 { "found 2!"} }"#,
description: "Iterate over each element, keeping null results",
result: Some(Value::test_list(vec![
Value::nothing(Span::test_data()),
Value::test_string("found 2!"),
Value::nothing(Span::test_data()),
])),
},
]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let head = call.head;
let closure: Closure = call.req(engine_state, stack, 0)?;
let keep_empty = call.has_flag(engine_state, stack, "keep-empty")?;
let metadata = input.metadata();
match input {
PipelineData::Empty => Ok(PipelineData::Empty),
PipelineData::Value(Value::Range { .. }, ..)
| PipelineData::Value(Value::List { .. }, ..)
| PipelineData::ListStream(..) => {
let mut closure = ClosureEval::new(engine_state, stack, closure);
Ok(input
.into_iter()
.map_while(move |value| {
let span = value.span();
let is_error = value.is_error();
match closure.run_with_value(value) {
Ok(PipelineData::ListStream(s, ..)) => {
let mut vals = vec![];
for v in s {
if let Value::Error { .. } = v {
return Some(v);
} else {
vals.push(v)
}
}
Some(Value::list(vals, span))
}
Ok(data) => Some(data.into_value(head).unwrap_or_else(|err| {
Value::error(chain_error_with_input(err, is_error, span), span)
})),
Err(error) => {
let error = chain_error_with_input(error, is_error, span);
Some(Value::error(error, span))
}
}
})
.into_pipeline_data(head, engine_state.signals().clone()))
}
PipelineData::ByteStream(stream, ..) => {
if let Some(chunks) = stream.chunks() {
let mut closure = ClosureEval::new(engine_state, stack, closure);
Ok(chunks
.map_while(move |value| {
let value = match value {
Ok(value) => value,
Err(err) => return Some(Value::error(err, head)),
};
let span = value.span();
let is_error = value.is_error();
match closure
.run_with_value(value)
.and_then(|data| data.into_value(head))
{
Ok(value) => Some(value),
Err(error) => {
let error = chain_error_with_input(error, is_error, span);
Some(Value::error(error, span))
}
}
})
.into_pipeline_data(head, engine_state.signals().clone()))
} else {
Ok(PipelineData::Empty)
}
}
PipelineData::Value(value, ..) => {
ClosureEvalOnce::new(engine_state, stack, closure).run_with_value(value)
}
}
.and_then(|x| {
x.filter(
move |x| if !keep_empty { !x.is_nothing() } else { true },
engine_state.signals(),
)
})
.map(|data| data.set_metadata(metadata))
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(Each {})
}
}