Merge pull request #1223 from guwirth/cpp17/fold-expressions

C++17 fold expressions

cxx-squid/src/test/resources/parser/own/C++17/fold-expression.cc

@@ -0,0 +1,54 @@
+#include <iostream>
+#include <vector>
+#include <climits>
+#include <cstdint>
+#include <type_traits>
+#include <utility>
+
+// n4618
+
+template<typename... Args>
+   bool f(Args... args) { 
+      return (true + ... + args);
+   } 
+
+template<typename... Args>
+   bool all(Args... args) { return (args && ...); }
+
+bool b = all(true, true, true, false);
+
+// cppreference sample
+
+template<typename ...Args>
+   void printer(Args&&... args) {
+      (std::cout << ... << args) << '\n';
+   }
+
+template<typename T, typename... Args>
+   void push_back_vec(std::vector<T>& v, Args&&... args)
+   {
+      (v.push_back(args), ...);
+   }
+
+// compile-time endianness swap based on http://stackoverflow.com/a/36937049 
+template<class T, std::size_t... N>
+constexpr T bswap_impl(T i, std::index_sequence<N...>) {
+  return (((i >> N*CHAR_BIT & std::uint8_t(-1)) << (sizeof(T)-1-N)*CHAR_BIT) | ...);
+}
+template<class T, class U = std::make_unsigned_t<T>>
+constexpr U bswap(T i) {
+  return bswap_impl<U>(i, std::make_index_sequence<sizeof(T)>{});
+}
+
+int main()
+{
+    printer(1, 2, 3, "abc");
+
+    std::vector<int> v;
+    push_back_vec(v, 6, 2, 45, 12);
+    push_back_vec(v, 1, 2, 9);
+    for (int i : v) std::cout << i << ' ';
+
+    static_assert(bswap<std::uint16_t>(0x1234u)==0x3412u);
+    static_assert(bswap<std::uint64_t>(0x0123456789abcdefULL)==0xefcdab8967452301ULL);
+}