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use nu_engine::column::get_columns;
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Span,
Type, Value,
};
#[derive(Clone)]
pub struct Columns;
impl Command for Columns {
fn name(&self) -> &str {
"columns"
}
fn signature(&self) -> Signature {
Signature::build(self.name())
.input_output_types(vec![
(Type::Table(vec![]), Type::List(Box::new(Type::String))),
(Type::Record(vec![]), Type::List(Box::new(Type::String))),
])
.category(Category::Filters)
}
fn usage(&self) -> &str {
"Given a record or table, produce a list of its columns' names."
}
fn extra_usage(&self) -> &str {
"This is a counterpart to `values`, which produces a list of columns' values."
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
example: "{ acronym:PWD, meaning:'Print Working Directory' } | columns",
description: "Get the columns from the record",
result: Some(Value::List {
vals: vec![Value::test_string("acronym"), Value::test_string("meaning")],
span: Span::test_data(),
}),
},
Example {
example: "[[name,age,grade]; [bill,20,a]] | columns",
description: "Get the columns from the table",
result: Some(Value::List {
vals: vec![
Value::test_string("name"),
Value::test_string("age"),
Value::test_string("grade"),
],
span: Span::test_data(),
}),
},
Example {
example: "[[name,age,grade]; [bill,20,a]] | columns | first",
description: "Get the first column from the table",
result: None,
},
Example {
example: "[[name,age,grade]; [bill,20,a]] | columns | select 1",
description: "Get the second column from the table",
result: None,
},
]
}
fn run(
&self,
engine_state: &EngineState,
_stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let span = call.head;
getcol(engine_state, span, input)
}
}
fn getcol(
engine_state: &EngineState,
head: Span,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let ctrlc = engine_state.ctrlc.clone();
let metadata = input.metadata();
match input {
PipelineData::Empty => Ok(PipelineData::Empty),
PipelineData::Value(
Value::List {
vals: input_vals,
span,
},
..,
) => {
let input_cols = get_columns(&input_vals);
Ok(input_cols
.into_iter()
.map(move |x| Value::String { val: x, span })
.into_pipeline_data(ctrlc)
.set_metadata(metadata))
}
PipelineData::Value(Value::CustomValue { val, span }, ..) => {
let input_as_base_value = val.to_base_value(span)?;
let input_cols = get_columns(&[input_as_base_value]);
Ok(input_cols
.into_iter()
.map(move |x| Value::String { val: x, span })
.into_pipeline_data(ctrlc)
.set_metadata(metadata))
}
PipelineData::ListStream(stream, ..) => {
let v: Vec<_> = stream.into_iter().collect();
let input_cols = get_columns(&v);
Ok(input_cols
.into_iter()
.map(move |x| Value::String { val: x, span: head })
.into_pipeline_data(ctrlc)
.set_metadata(metadata))
}
PipelineData::Value(Value::LazyRecord { val, .. }, ..) => Ok(val
.column_names()
.into_iter()
.map(move |x| Value::String {
val: x.into(),
span: head,
})
.into_pipeline_data(ctrlc)
.set_metadata(metadata)),
PipelineData::Value(Value::Record { cols, .. }, ..) => Ok(cols
.into_iter()
.map(move |x| Value::String { val: x, span: head })
.into_pipeline_data(ctrlc)
.set_metadata(metadata)),
PipelineData::Value(Value::Error { error }, ..) => Err(*error),
PipelineData::Value(other, ..) => Err(ShellError::OnlySupportsThisInputType {
exp_input_type: "record or table".into(),
wrong_type: other.get_type().to_string(),
dst_span: head,
src_span: other.expect_span(),
}),
PipelineData::ExternalStream { .. } => Err(ShellError::OnlySupportsThisInputType {
exp_input_type: "record or table".into(),
wrong_type: "raw data".into(),
dst_span: head,
src_span: input
.span()
.expect("PipelineData::ExternalStream had no span"),
}),
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(Columns {})
}
}