nextAllocMax

    pub fn nextAllocMax(self: *@This(), allocator: Allocator, when: AllocWhen, max_value_len: usize) Reader.AllocError!Token {
        const token_type = try self.peekNextTokenType();
        switch (token_type) {
            .number, .string => {
                var value_list = std.array_list.Managed(u8).init(allocator);
                errdefer {
                    value_list.deinit();
                }
                if (try self.allocNextIntoArrayListMax(&value_list, when, max_value_len)) |slice| {
                    return if (token_type == .number)
                        Token{ .number = slice }
                    else
                        Token{ .string = slice };
                } else {
                    return if (token_type == .number)
                        Token{ .allocated_number = try value_list.toOwnedSlice() }
                    else
                        Token{ .allocated_string = try value_list.toOwnedSlice() };
                }
            },

            // Simple tokens never alloc.
            .object_begin,
            .object_end,
            .array_begin,
            .array_end,
            .true,
            .false,
            .null,
            .end_of_document,
            => return try self.next(),
        }
    }