WIP: ATmodem (renamed after BG95_base) and sequencer

include/drv/ATmodem.h

@@ -1,7 +1,7 @@
 /*!
- * \file cont/BG95_base.h
+ * \file drv/ATmodem.h
  * \brief
- *      BG95 driver functionality as CRTP base class
+ *      ATmodem driver functionality as CRTP base class
  *
  * \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
  *
@@ -28,8 +28,8 @@
  * </dd></dl>
  */
 
-#ifndef TBX_DRV_BG95_base_H_
-#define TBX_DRV_BG95_base_H_
+#ifndef TBX_DRV_ATmodem_H_
+#define TBX_DRV_ATmodem_H_
 
 #define __cplusplus 201703L
 
@@ -37,7 +37,7 @@
 #include <core/crtp.h>
 #include <cont/equeue.h>
 #include <cont/range.h>
-#include <utils/sequencer.h>
+#include <com/sequencer.h>
 
 #include <cstring>
 #include <cstdlib>
@@ -63,12 +63,12 @@ namespace tbx {
  * \tparam Delimiter
  */
 template<typename Impl_t, size_t N, char Delimiter ='\n'>
-class BG95_base
-        : public sequencer<BG95_base<Impl_t, N, Delimiter>, char, N>{
+class ATmodem
+        : public sequencer<ATmodem<Impl_t, N, Delimiter>, char, N>{
         _CRTP_IMPL(Impl_t);
 
         // local type dispatch
-        using base_type     = sequencer<BG95_base, char, N>;
+        using base_type     = sequencer<ATmodem, char, N>;
 
     //! \name Public types
     //! @{
@@ -106,10 +106,10 @@ class BG95_base
     //!@{
     protected:
         //!< \brief A default constructor from derived only
-        BG95_base() = default;
-        ~BG95_base () = default;                            //!< \brief Allow destructor from derived only
-        BG95_base(const BG95_base&) = delete;               //!< No copies
-        BG95_base& operator= (const BG95_base&) = delete;   //!< No copy assignments
+        ATmodem() noexcept = default;
+        ~ATmodem () = default;                          //!< \brief Allow destructor from derived only
+        ATmodem(const ATmodem&) = delete;               //!< No copies
+        ATmodem& operator= (const ATmodem&) = delete;   //!< No copy assignments
     //!@}
 
     //! \name Sequencer interface requirements
@@ -139,6 +139,28 @@ class BG95_base
     //! \name Private functionality
     //! @{
     private:
+
+        template <typename... Ts>
+        struct typelist {
+            using type = typelist;   //!< act as identity
+        };
+
+        template <typename L>
+        struct front_impl {
+            using type = void;
+        };
+
+        template <typename Head, typename... Tail>
+        struct front_impl<typelist<Head, Tail...>> {
+            using type = Head;
+        };
+
+        //! Return the first element in \c meta::typelist \c List.
+        //!
+        //! Complexity \f$ O(1) \f$.
+        template <typename List>
+        using front = typename front_impl<List>::type;
+
         template<typename T>
         void extract (const char* str, T* value) {
             static_assert (
@@ -154,6 +176,9 @@ class BG95_base
                 std::strcpy(value, str);
             }
         }
+        void extract (const char* str, void* value) {
+            (void)*str; (void)value;
+        }
 
         template <char Marker = '%'>
         std::pair<size_t, bool> parse (const char* expected, const string_view buffer, char* token) {
@@ -253,29 +278,45 @@ class BG95_base
          *    if (done && status == 1)
          *       std::cout << "Connected to home network\n"
          * \endcode
+         * element_type (&arr)[N]
          */
-        template <typename T, char Marker = '%'>
-        bool command (const string_view cmd, const string_view expected, T* value, clock_t timeout =0) {
-            char buffer[N];
-            char token[N];
+        template<char Marker = '%', typename ...Ts>
+        bool command (const string_view cmd, const string_view expected, clock_t timeout, Ts* ...values) {
 
-            transmit(cmd.data());                       // send command
+            constexpr size_t Nr = sizeof...(Ts);
+            front<typelist<Ts...>>* vargs[Nr] = {values...};
+
+            if constexpr (Nr == 0) { (void)vargs; }
+
+            char buffer[N], token[N];
+            size_t v =0;
+
+            transmit(cmd.data());                           // send command
 
             for (auto ex = expected.begin() ; ex != expected.end() ;  ) {
-                clock_t mark = clock();                 // load the answer with timeout
+                clock_t mark = clock();                     // load the answer with timeout
                 size_t sz =0;
-                do {
-                    sz = receive(buffer);
-                	if ((timeout != 0 )&& ((clock() - mark) >= timeout))
-                	    return false;
-                } while (!sz);
+                bool redo = false; do {
+                    do {
+                        sz = receive(buffer);
+                        if ((timeout != 0 )&& ((clock() - mark) >= timeout))
+                            return false;
+                    } while (!sz);
 
-                for (size_t i=0 ; i<sz ; ) {            // parse buffer based on expected
-                    auto [step, marker] = parse<Marker> (ex++, {&buffer[i], sz-i}, token);
-                    if (!step)      return false;
-                    if (marker)     extract(token, value);
-                    i += step;
-                }
+                    redo = false;                           // have faith to parse successfully
+                    for (size_t i=0 ; i<sz ; ) {            // parse buffer based on expected
+                        auto [step, marker] = parse<Marker> (ex++, {&buffer[i], sz-i}, token);
+                        if (!step) {
+                            redo = true;                    // fail to parse, reload and retry
+                            break;
+                        }
+                        if constexpr (Nr > 0) {
+                            if (marker && v< Nr)
+                                extract(token, vargs[v++]);
+                        }
+                        i += step;
+                    }
+                } while (redo);
             }
             return true;
         }
@@ -324,4 +365,4 @@ class BG95_base
 
 } // namespace tbx;
 
-#endif /* TBX_DRV_BG95_base_H_ */
+#endif /* #ifndef TBX_DRV_ATmodem_H_ */