Function process_array_in

prqlc/prqlc/src/sql/gen_expr.rs:171–210

Translates into IN (v1, v2, ...) if possible

(
    expr: &rq::Expr,
    args: &[rq::Expr],
    ctx: &mut Context,
)

/// Translates into IN (v1, v2, ...) if possible
fn process_array_in(
    expr: &rq::Expr,
    args: &[rq::Expr],
    ctx: &mut Context,
) -> Result<sql_ast::Expr> {
    match args {
        [col_expr @ rq::Expr {
            kind:
                rq::ExprKind::ColumnRef(_)
                | rq::ExprKind::Literal(_)
                | rq::ExprKind::SString(_)
                | rq::ExprKind::Param(_)
                | rq::ExprKind::Operator { name: _, args: _ },
            ..
        }, rq::Expr {
            kind: rq::ExprKind::Array(in_values),
            ..
        }] => {
            if in_values.is_empty() {
                // We avoid producing `in ()` expressions since they are not syntactically valid
                // in some engines like PostgreSQL or MySQL.
                // We can instead optimize this to a condition that is always false
                Ok(sql_ast::Expr::Value(Value::Boolean(false).into()))
            } else {
                Ok(sql_ast::Expr::InList {
                    expr: Box::new(translate_expr(col_expr.clone(), ctx)?.into_ast()),
                    list: in_values
                        .iter()
                        .map(|a| Ok(translate_expr(a.clone(), ctx)?.into_ast()))
                        .collect::<Result<Vec<sql_ast::Expr>>>()?,
                    negated: false,
                })
            }
        }
        _ => Err(
            Error::new_simple("args to `std.array_in` must be an expression and an array")
                .with_span(expr.span),
        ),
    }
}

/// Translates PRQL date truncation to dialect-specific SQL.
/// BigQuery uses unquoted uppercase date_part after the column: DATE_TRUNC(col, DAY)