pub use super::uniq;
use nu_engine::column::nonexistent_column;
use nu_engine::CallExt;
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
record, Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
};
#[derive(Clone)]
pub struct UniqBy;
impl Command for UniqBy {
fn name(&self) -> &str {
"uniq-by"
}
fn signature(&self) -> Signature {
Signature::build("uniq-by")
.input_output_types(vec![
(Type::Table(vec![]), Type::Table(vec![])),
(
Type::List(Box::new(Type::Any)),
Type::List(Box::new(Type::Any)),
),
])
.rest("columns", SyntaxShape::Any, "The column(s) to filter by.")
.switch(
"count",
"Return a table containing the distinct input values together with their counts",
Some('c'),
)
.switch(
"repeated",
"Return the input values that occur more than once",
Some('d'),
)
.switch(
"ignore-case",
"Ignore differences in case when comparing input values",
Some('i'),
)
.switch(
"unique",
"Return the input values that occur once only",
Some('u'),
)
.allow_variants_without_examples(true)
.category(Category::Filters)
}
fn usage(&self) -> &str {
"Return the distinct values in the input by the given column(s)."
}
fn search_terms(&self) -> Vec<&str> {
vec!["distinct", "deduplicate"]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let columns: Vec<String> = call.rest(engine_state, stack, 0)?;
if columns.is_empty() {
return Err(ShellError::MissingParameter {
param_name: "columns".into(),
span: call.head,
});
}
let metadata = input.metadata();
let vec: Vec<_> = input.into_iter().collect();
match validate(&vec, &columns, call.head) {
Ok(_) => {}
Err(err) => {
return Err(err);
}
}
let mapper = Box::new(item_mapper_by_col(columns));
uniq(engine_state, stack, call, vec, mapper, metadata)
}
fn examples(&self) -> Vec<Example> {
vec![Example {
description: "Get rows from table filtered by column uniqueness ",
example: "[[fruit count]; [apple 9] [apple 2] [pear 3] [orange 7]] | uniq-by fruit",
result: Some(Value::test_list(vec![
Value::test_record(record! {
"fruit" => Value::test_string("apple"),
"count" => Value::test_int(9),
}),
Value::test_record(record! {
"fruit" => Value::test_string("pear"),
"count" => Value::test_int(3),
}),
Value::test_record(record! {
"fruit" => Value::test_string("orange"),
"count" => Value::test_int(7),
}),
])),
}]
}
}
fn validate(vec: &[Value], columns: &[String], span: Span) -> Result<(), ShellError> {
let first = vec.first();
if let Some(v) = first {
let val_span = v.span();
if let Value::Record { val: record, .. } = &v {
if columns.is_empty() {
return Err(ShellError::GenericError {
error: "expected name".into(),
msg: "requires a column name to filter table data".into(),
span: Some(span),
help: None,
inner: vec![],
});
}
if let Some(nonexistent) = nonexistent_column(columns, record.columns()) {
return Err(ShellError::CantFindColumn {
col_name: nonexistent,
span,
src_span: val_span,
});
}
}
}
Ok(())
}
fn get_data_by_columns(columns: &[String], item: &Value) -> Vec<Value> {
columns
.iter()
.filter_map(|col| item.get_data_by_key(col))
.collect::<Vec<_>>()
}
fn item_mapper_by_col(cols: Vec<String>) -> impl Fn(crate::ItemMapperState) -> crate::ValueCounter {
let columns = cols;
Box::new(move |ms: crate::ItemMapperState| -> crate::ValueCounter {
let item_column_values = get_data_by_columns(&columns, &ms.item);
let col_vals = Value::list(item_column_values, Span::unknown());
crate::ValueCounter::new_vals_to_compare(ms.item, ms.flag_ignore_case, col_vals, ms.index)
})
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(UniqBy {})
}
}