Function parse_constant

src/expr-parser/src/parser.rs:123–147

(ctx: CtxRef, input: ParseStream)

    }

    fn parse_constant(ctx: CtxRef, input: ParseStream) -> Result {
        let constant = input.parse::<kw::Constant>()?;

        let parse_typ = |input: ParseStream| -> syn::Result<ReprRelationType> {
            let analyses = analyses::parse_analyses(input)?;
            let Some(column_types) = analyses.types else {
                let msg = "Missing expected `types` analyses for Constant line";
                Err(Error::new(input.span(), msg))?
            };
            let keys = analyses.keys.unwrap_or_default();
            Ok(ReprRelationType::new(column_types).with_keys(keys))
        };
        if input.eat3(syn::Token![<], kw::empty, syn::Token![>]) {
            let typ = parse_typ(input)?;
            Ok(MirRelationExpr::Constant {
                rows: Ok(vec![]),
                typ,
            })
        } else {
            let typ = parse_typ(input)?;
            let parse_children = ParseChildren::new(input, constant.span().start());
            let rows = Ok(parse_children.parse_many(ctx, parse_constant_entry)?);
            Ok(MirRelationExpr::Constant { rows, typ })
        }
    }

    fn parse_constant_entry(_ctx: CtxRef, input: ParseStream) -> syn::Result<(Row, Diff)> {
        input.parse::<syn::Token![-]>()?;