Function parse_union

src/expr-parser/src/parser.rs:605–614

(ctx: CtxRef, input: ParseStream)

    }

    fn parse_union(ctx: CtxRef, input: ParseStream) -> Result {
        let union = input.parse::<kw::Union>()?;

        let parse_inputs = ParseChildren::new(input, union.span().start());
        let mut children = parse_inputs.parse_many(ctx, parse_expr)?;
        let inputs = children.split_off(1);
        let base = Box::new(children.into_element());

        Ok(MirRelationExpr::Union { base, inputs })
    }

    fn parse_arrange_by(ctx: CtxRef, input: ParseStream) -> Result {
        let arrange_by = input.parse::<kw::ArrangeBy>()?;