nu_engine/
column.rs

1use nu_protocol::Value;
2use std::collections::HashSet;
3
4pub fn get_columns(input: &[Value]) -> Vec<String> {
5    let mut column_set = HashSet::new();
6    let mut columns = Vec::new();
7    for item in input {
8        let Value::Record { val, .. } = item else {
9            return vec![];
10        };
11
12        for col in val.columns() {
13            if column_set.insert(col) {
14                columns.push(col.to_string());
15            }
16        }
17    }
18
19    columns
20}
21
22// If a column doesn't exist in the input, return it.
23pub fn nonexistent_column<'a, I>(inputs: &[String], columns: I) -> Option<String>
24where
25    I: IntoIterator<Item = &'a String>,
26{
27    let set: HashSet<&String> = HashSet::from_iter(columns);
28
29    for input in inputs {
30        if set.contains(input) {
31            continue;
32        }
33        return Some(input.clone());
34    }
35    None
36}