125 struct scan_handler : error_handler {  struct
128   scan_context scan_ctx_;
129   scan_args args_;
130   int next_arg_id_;
131   scan_arg arg_;
133   template <typename T = unsigned> T read_uint() {  in read_uint()
157   scan_handler(string_view format, string_view input, scan_args args)  in scan_handler()  argument
160   const char* pos() const { return scan_ctx_.begin(); }  in pos()
162   void on_text(const char* begin, const char* end) {  in on_text()
172   int on_arg_id() { return on_arg_id(next_arg_id_++); }  in on_arg_id()
173   int on_arg_id(int id) {  in on_arg_id()
178   int on_arg_id(string_view) { return on_error("invalid format"), 0; }  in on_arg_id()
180   void on_replacement_field(int, const char*) {  in on_replacement_field()
228   detail::scan_handler h(format_str, input, args);  in vscan()  argument