Function remove_scope

datafusion/expr/src/higher_order_function.rs:1330–1354

(
    vars: &mut HashMap<String, Vec<FieldRef>>,
    scope: &[String],
)

}

fn remove_scope(
    vars: &mut HashMap<String, Vec<FieldRef>>,
    scope: &[String],
) -> Result<()> {
    for param in scope {
        match vars.entry_ref(param) {
            EntryRef::Occupied(mut v) => {
                if v.get().len() == 1 {
                    v.remove();
                } else {
                    v.get_mut().pop().ok_or_else(|| {
                        internal_datafusion_err!(
                            "every entry should have at least one field"
                        )
                    })?;
                }
            }
            EntryRef::Vacant(_v) => {
                return internal_err!("no empty value should be in the map");
            }
        }
    }

    Ok(())
}

fn all_unique(params: &[String]) -> bool {
    match params.len() {