Handle iterator types in typeName, RESTProcess and json_pack/unpack. Requires C++11 or later.

Author: highperformancecoder

RESTProcess_base.h

@@ -1291,7 +1291,7 @@ namespace classdesc
 
 namespace classdesc_access
 {
-  template <class T> struct access_RESTProcess;
+  template <class T, class Enable=void> struct access_RESTProcess;
 }
 
 namespace std

RESTProcess_epilogue.h

@@ -47,6 +47,10 @@ namespace classdesc_access
   struct access_RESTProcess<cd::PolyPack<T>>: 
     public cd::NullDescriptor<cd::RESTProcess_t> {};
 
+  template <class T>
+  struct access_RESTProcess<T, cd::void_t<typename std::iterator_traits<T>::value_type>>:
+    public cd::NullDescriptor<cd::RESTProcess_t> {};
+
 }
 
 namespace classdesc

classdesc.cc

@@ -194,7 +194,7 @@ struct MemberSig
     declName(d), returnType(r), argList(a), prefix(p), name(n), type(t) {}
   string declare() {
     // If qualified type, the typename qualifier required
-    auto rType=returnType.find("::")!=string::npos && returnType.find("typename ")==string::npos? "typename "+returnType: returnType;
+    string rType=returnType.find("::")!=string::npos && returnType.find("typename ")==string::npos? "typename "+returnType: returnType;
     switch (type)
       {
       case none:

classdesc.h

@@ -146,6 +146,10 @@ namespace classdesc
   using std::is_copy_constructible;
   using std::is_assignable;
 
+  // useful utility for SFINAE calculations
+  // See https://isocpp.org/files/papers/N3911.pdf
+  template <typename... > using void_t = void;
+  
   // missing from std, so supply here in classdesc
   template <class T, class... Args>
   std::unique_ptr<T> make_unique(Args... args)
@@ -320,6 +324,10 @@ namespace classdesc
     static const bool value=true;};
 
 #if defined(__cplusplus) && __cplusplus>=201103L
+  template <class T, class=void> struct is_iterator: public false_type {};
+  template <class T> struct is_iterator<T, void_t<typename std::iterator_traits<T>::iterator_category>>:
+    public true_type {};
+
   template <class K, class V, class H, class P, class A> 
   struct is_associative_container<std::unordered_map<K,V,H,P,A> > {
     static const bool value=true;};

classdesc_access.h

@@ -22,8 +22,8 @@ namespace classdesc_access
   template <class T> struct access_unpack;
   template <class T> struct access_xml_pack;
   template <class T> struct access_xml_unpack;
-  template <class T> struct access_json_pack;
-  template <class T> struct access_json_unpack;
+  template <class T, class Enable> struct access_json_pack;
+  template <class T, class Enable> struct access_json_unpack;
   template <class T> struct access_random_init;
 }
 
@@ -39,8 +39,8 @@ namespace classdesc_access
   friend struct classdesc_access::access_unpack<type>;                  \
   friend struct classdesc_access::access_xml_pack<type>;                \
   friend struct classdesc_access::access_xml_unpack<type>;              \
-  friend struct classdesc_access::access_json_pack<type>;               \
-  friend struct classdesc_access::access_json_unpack<type>;             \
+  friend struct classdesc_access::access_json_pack<type,void>;          \
+  friend struct classdesc_access::access_json_unpack<type,void>;        \
   friend struct classdesc_access::access_random_init<type>
 
 // for backward compatibility. Deprecated.

json_pack_base.h

@@ -636,8 +636,8 @@ inline std::ostream& operator<<(std::ostream& o, const json5_parser::mValue& x)
 
 namespace classdesc_access
 {
-  template <class T> struct access_json_pack;
-  template <class T> struct access_json_unpack;
+  template <class T, class Enable=void> struct access_json_pack;
+  template <class T, class Enable=void> struct access_json_unpack;
 }
 
 #include "use_mbr_pointers.h"

json_pack_epilogue.h

@@ -74,9 +74,19 @@ namespace classdesc_access
 {
   namespace cd=classdesc;
 
+#if defined(__cplusplus) && __cplusplus>=201103L  
+  // nobble iterators
+  template <class T>
+  struct access_json_pack<T, cd::void_t<typename std::iterator_traits<T>::value_type>>:
+    public cd::NullDescriptor<cd::json_pack_t> {};
+  template <class T>
+  struct access_json_unpack<T, cd::void_t<typename std::iterator_traits<T>::value_type>>:
+    public cd::NullDescriptor<cd::json_unpack_t> {};
+#endif
+  
 #ifndef JSON_PACK_NO_FALL_THROUGH_TO_STREAMING
   // fall through to streaming operators
-  template <class T>
+  template <class T,class Enable>
   struct access_json_pack
   {
   public:
@@ -88,7 +98,7 @@ namespace classdesc_access
     }
   };
 
-  template <class T>
+  template <class T,class Enable>
   struct access_json_unpack
   {
   public:

typeName_epilogue.h

@@ -26,6 +26,14 @@ namespace classdesc
   enable_if<And<Not<is_const<T> >,is_integral<T> >,std::string>::T
   typeNamep() {return integralTypeName<T>();}
 
+#if defined(__cplusplus) && __cplusplus>=201103L  
+  template <class T>
+  struct tn<T, void_t<typename std::iterator_traits<T>::value_type>>
+  {
+    static std::string name() {return "iterator";}
+  };
+#endif
+  
   template <class T> typename
   enable_if<
     And<
@@ -39,9 +47,8 @@ namespace classdesc
   typeNamep() {return "const "+typeName<typename remove_const<T>::type>();}
 
   template <class T>
-  typename enable_if<And<Not<is_function<T> >, Not<is_member_function_pointer<T> > >,  std::string>::T
+  typename enable_if<And<Not<is_function<T> >,Not<is_member_function_pointer<T> > >,  std::string>::T
   typeName() {return typeNamep<T>();}
-
 
 #if defined(__cplusplus) && __cplusplus>=201103L
   template <class T>