Function range

regex/regex-syntax/src/ast/parse.rs:4290–4314

(span: Span, start: char, end: char)

        }

        fn range(span: Span, start: char, end: char) -> ast::ClassSetItem {
            let pos1 = Position {
                offset: span.start.offset + start.len_utf8(),
                column: span.start.column + 1,
                ..span.start
            };
            let pos2 = Position {
                offset: span.end.offset - end.len_utf8(),
                column: span.end.column - 1,
                ..span.end
            };
            ast::ClassSetItem::Range(ast::ClassSetRange {
                span: span,
                start: ast::Literal {
                    span: Span { end: pos1, ..span },
                    kind: ast::LiteralKind::Verbatim,
                    c: start,
                },
                end: ast::Literal {
                    span: Span { start: pos2, ..span },
                    kind: ast::LiteralKind::Verbatim,
                    c: end,
                },
            })
        }

        fn alnum(span: Span, negated: bool) -> ast::ClassAscii {
            ast::ClassAscii {