Merge pull request #249 from dean0x7d/variadic-v3

Reduce compile time of variadic functions (2)

format.h

@@ -1211,17 +1211,27 @@ class MakeValue : public Arg {
   static uint64_t type(const NamedArg<Char_> &) { return Arg::NAMED_ARG; }
 };
 
+template <typename Formatter>
+class MakeArg : public Arg {
+public:
+  MakeArg() {
+    type = Arg::NONE;
+  }
+
+  template <typename T>
+  MakeArg(const T &value)
+  : Arg(MakeValue<Formatter>(value)) {
+    type = static_cast<Arg::Type>(MakeValue<Formatter>::type(value));
+  }
+};
+
 template <typename Char>
 struct NamedArg : Arg {
   BasicStringRef<Char> name;
 
-  typedef internal::MakeValue< BasicFormatter<Char> > MakeValue;
-
   template <typename T>
   NamedArg(BasicStringRef<Char> argname, const T &value)
-  : Arg(MakeValue(value)), name(argname) {
-    type = static_cast<Arg::Type>(MakeValue::type(value));
-  }
+  : Arg(MakeArg< BasicFormatter<Char> >(value)), name(argname) {}
 };
 
 #define FMT_DISPATCH(call) static_cast<Impl*>(this)->call
@@ -1913,16 +1923,23 @@ inline uint64_t make_type(const T &arg) {
   return MakeValue< BasicFormatter<char> >::type(arg);
 }
 
+template <unsigned N, bool/*IsPacked*/= (N < ArgList::MAX_PACKED_ARGS)>
+struct ArgArray;
+
+template <unsigned N>
+struct ArgArray<N, true/*IsPacked*/> {
+  typedef Value Type[N > 0 ? N : 1];
+
+  template <typename Formatter, typename T>
+  static Value make(const T &value) { return MakeValue<Formatter>(value); }
+};
+
 template <unsigned N>
-struct ArgArray {
-  // Computes the argument array size by adding 1 to N, which is the number of
-  // arguments, if N is zero, because array of zero size is invalid, or if N
-  // is greater than ArgList::MAX_PACKED_ARGS to accommodate for an extra
-  // argument that marks the end of the list.
-  enum { SIZE = N + (N == 0 || N >= ArgList::MAX_PACKED_ARGS ? 1 : 0) };
-
-  typedef typename Conditional<
-    (N < ArgList::MAX_PACKED_ARGS), Value, Arg>::type Type[SIZE];
+struct ArgArray<N, false/*IsPacked*/> {
+  typedef Arg Type[N + 1]; // +1 for the list end Arg::NONE
+
+  template <typename Formatter, typename T>
+  static Arg make(const T &value) { return MakeArg<Formatter>(value); }
 };
 
 #if FMT_USE_VARIADIC_TEMPLATES
@@ -1931,47 +1948,6 @@ inline uint64_t make_type(const Arg &first, const Args & ... tail) {
   return make_type(first) | (make_type(tail...) << 4);
 }
 
-inline void do_set_types(Arg *) {}
-
-template <typename T, typename... Args>
-inline void do_set_types(Arg *args, const T &arg, const Args & ... tail) {
-  args->type = static_cast<Arg::Type>(
-        MakeValue< BasicFormatter<char> >::type(arg));
-  do_set_types(args + 1, tail...);
-}
-
-template <typename... Args>
-inline void set_types(Arg *array, const Args & ... args) {
-  if (check(sizeof...(Args) > ArgList::MAX_PACKED_ARGS))
-    do_set_types(array, args...);
-  array[sizeof...(Args)].type = Arg::NONE;
-}
-
-template <typename... Args>
-inline void set_types(Value *, const Args & ...) {
-  // Do nothing as types are passed separately from values.
-}
-
-template <typename Formatter, typename Value>
-inline void store_args(Value *) {}
-
-template <typename Formatter, typename Arg, typename T, typename... Args>
-inline void store_args(Arg *args, const T &arg, const Args & ... tail) {
-  // Assign only the Value subobject of Arg and don't overwrite type (if any)
-  // that is assigned by set_types.
-  Value &value = *args;
-  value = MakeValue<Formatter>(arg);
-  store_args<Formatter>(args + 1, tail...);
-}
-
-template <typename Formatter, typename... Args>
-ArgList make_arg_list(typename ArgArray<sizeof...(Args)>::Type array,
-                      const Args & ... args) {
-  if (check(sizeof...(Args) >= ArgList::MAX_PACKED_ARGS))
-    set_types(array, args...);
-  store_args<Formatter>(array, args...);
-  return ArgList(make_type(args...), array);
-}
 #else
 
 struct ArgType {
@@ -2039,18 +2015,20 @@ class FormatBuf : public std::basic_streambuf<Char> {
 # define FMT_VARIADIC_VOID(func, arg_type) \
   template <typename... Args> \
   void func(arg_type arg0, const Args & ... args) { \
-    typename fmt::internal::ArgArray<sizeof...(Args)>::Type array; \
-    func(arg0, fmt::internal::make_arg_list< \
-      fmt::BasicFormatter<Char> >(array, args...)); \
+    typedef fmt::internal::ArgArray<sizeof...(Args)> ArgArray; \
+    typename ArgArray::Type array{ \
+      ArgArray::template make<fmt::BasicFormatter<Char> >(args)...}; \
+    func(arg0, fmt::ArgList(fmt::internal::make_type(args...), array)); \
   }
 
 // Defines a variadic constructor.
 # define FMT_VARIADIC_CTOR(ctor, func, arg0_type, arg1_type) \
   template <typename... Args> \
   ctor(arg0_type arg0, arg1_type arg1, const Args & ... args) { \
-    typename fmt::internal::ArgArray<sizeof...(Args)>::Type array; \
-    func(arg0, arg1, fmt::internal::make_arg_list< \
-      fmt::BasicFormatter<Char> >(array, args...)); \
+    typedef fmt::internal::ArgArray<sizeof...(Args)> ArgArray; \
+    typename ArgArray::Type array{ \
+      ArgArray::template make<fmt::BasicFormatter<Char> >(args)...}; \
+    func(arg0, arg1, fmt::ArgList(fmt::internal::make_type(args...), array)); \
   }
 
 #else
@@ -2944,10 +2922,8 @@ void format(BasicFormatter<Char> &f, const Char *&format_str, const T &value) {
   output << value;
 
   BasicStringRef<Char> str(&buffer[0], format_buf.size());
-  typedef internal::MakeValue< BasicFormatter<Char> > MakeValue;
-  internal::Arg arg = MakeValue(str);
-  arg.type = static_cast<internal::Arg::Type>(MakeValue::type(str));
-  format_str = f.format(format_str, arg);
+  typedef internal::MakeArg< BasicFormatter<Char> > MakeArg;
+  format_str = f.format(format_str, MakeArg(str));
 }
 
 // Reports a system error without throwing an exception.
@@ -3271,10 +3247,11 @@ void arg(WStringRef, const internal::NamedArg<Char>&) FMT_DELETED_OR_UNDEFINED;
   template <typename... Args> \
   ReturnType func(FMT_FOR_EACH(FMT_ADD_ARG_NAME, __VA_ARGS__), \
       const Args & ... args) { \
-    typename fmt::internal::ArgArray<sizeof...(Args)>::Type array; \
+    typedef fmt::internal::ArgArray<sizeof...(Args)> ArgArray; \
+    typename ArgArray::Type array{ \
+      ArgArray::template make<fmt::BasicFormatter<Char> >(args)...}; \
     call(FMT_FOR_EACH(FMT_GET_ARG_NAME, __VA_ARGS__), \
-      fmt::internal::make_arg_list< \
-        fmt::BasicFormatter<Char> >(array, args...)); \
+      fmt::ArgList(fmt::internal::make_type(args...), array)); \
   }
 #else
 // Defines a wrapper for a function taking __VA_ARGS__ arguments