Function try_into_exprs

prqlc/prqlc/src/sql/gen_projection.rs:18–53

(
    cids: Vec<CId>,
    ctx: &mut Context,
    span: Option<Span>,
)

use crate::{Error, Span, WithErrorInfo};

pub(super) fn try_into_exprs(
    cids: Vec<CId>,
    ctx: &mut Context,
    span: Option<Span>,
) -> Result<Vec<sql_ast::Expr>> {
    let (cids, excluded) = translate_wildcards(&ctx.anchor, cids);

    let mut res = Vec::new();
    for cid in cids {
        let decl = ctx.anchor.column_decls.get(&cid).unwrap();

        let ColumnDecl::RelationColumn(riid, _, RelationColumn::Wildcard) = decl else {
            // base case
            res.push(translate_cid(cid, ctx)?.into_ast());
            continue;
        };

        // star
        let t = &ctx.anchor.relation_instances[riid];
        let table_name = t.table_ref.name.clone().map(Ident::from_name);

        let ident = translate_star(ctx, span)?;
        if let Some(excluded) = excluded.get(&cid) {
            if !excluded.is_empty() {
                return Err(
                    Error::new_simple("Excluding columns not supported in this position")
                        .with_span(span),
                );
            }
        }
        let ident = translate_ident(table_name, Some(ident), ctx);

        res.push(sql_ast::Expr::CompoundIdentifier(ident));
    }
    Ok(res)
}

type Excluded = HashMap<CId, HashSet<CId>>;