tuple tools : add reverse for a tuple...

- add in std:: the reverse to be able to apply the algorithms on a
  reversed tuple
- overloaded std::get, std::tuple_size for this
- added tests.

test/triqs/utility/tuple_tools.cpp

@@ -41,7 +41,7 @@ struct print_t {
 
 struct A {
 template<typename T1, typename T2>  
-  std::string str(T1 const & x, T2 const &y) const { std::stringstream fs; fs << "the string is "<< x<<" " << y; return fs.str();}
+  std::string str(T1 const & x, T2 const &y) const { std::stringstream fs; fs << "A : the string is "<< x<<" " << y; return fs.str();}
 };
 
 std::string my_print_str(int x, int y) { std::stringstream fs; fs << "the string is "<< x<< " " << y; return fs.str();}
@@ -61,6 +61,11 @@ int main(int argc, char **argv) {
   std::cerr << std::endl;
  }
 
+ {
+  triqs::tuple::for_each(reverse(t), print_t());
+  std::cerr << std::endl;
+ }
+
  {
   auto res = triqs::tuple::apply(fun(),t);
   std::cerr  << " f(t) =" << res << std::endl ;
@@ -76,21 +81,38 @@ int main(int argc, char **argv) {
    << std::get<3>(r) << std::endl;
  }
 
+  std::cerr  << "  ----- fold ----"<< std::endl ;
+ 
  {
   auto res = triqs::tuple::fold([](double x,double r) { return x+r;}, t, 0);
   std::cerr  << " " << res << std::endl ;
   if ( std::abs((res -  15.6)) > 1.e-13) throw std::runtime_error(" ");
  }
 
+ {
+  auto res = triqs::tuple::fold([](double x,double y) { return x+2*y;}, t, 0);
+  std::cerr  << " " << res << std::endl ;
+  if ( std::abs((res -  33.8)) > 1.e-13) throw std::runtime_error(" ");
+ }
+
+{
+  auto res = triqs::tuple::fold([](double x,double y) { return x+2*y;}, reverse(t), 0);
+  std::cerr  << " " << res << std::endl ;
+  if ( std::abs((res -  86.8)) > 1.e-13) throw std::runtime_error(" ");
+ }
+
  {
   auto res = triqs::tuple::fold_on_zip([](double x, double y, double r) { return x+ 2*y +r;}, t1,t2, 0);
   std::cerr  << " " << res << std::endl ;
   if ( std::abs((res -  35.6)) > 1.e-13) throw std::runtime_error(" ");
  }
 
+  std::cerr  << "  ----- apply ----"<< std::endl ;
  {
   auto res = triqs::tuple::apply(my_print_str, std::make_tuple(1,2));
   std::cerr  << " " << res << std::endl ;
+  res = triqs::tuple::apply(my_print_str, reverse(std::make_tuple(1,2)));
+  std::cerr  << " " << res << std::endl ;
  }
 
  {

triqs/utility/mini_vector.hpp

@@ -65,7 +65,7 @@ namespace triqs { namespace utility {
    }
 
    mini_vector & operator=(const mini_vector & x){ for (int i=0;i<Rank; ++i) _data[i] = x._data[i]; return *this;}
-   mini_vector & operator=(mini_vector && x){ swap(*this,x); return *this;}
+   mini_vector & operator=(mini_vector && x) = default; 
 
    friend void swap(mini_vector & a, mini_vector & b) { std::swap(a._data, b._data);}
 

triqs/utility/tuple_tools.hpp

@@ -24,6 +24,22 @@
 #include <tuple>
 #include <sstream>
 
+// adding to the std lib the reversed lazy tuple...
+// overloading & specializing only the functions needed here.
+namespace std {
+  template<typename TU> struct _triqs_reversed_tuple {TU _x;};
+
+  template<typename ... T> _triqs_reversed_tuple<std::tuple<T...>>        reverse(std::tuple<T...> && x) { return {move(x)};}
+  template<typename ... T> _triqs_reversed_tuple<std::tuple<T...>&>       reverse(std::tuple<T...> & x) { return {x};}
+  template<typename ... T> _triqs_reversed_tuple<std::tuple<T...>const &> reverse(std::tuple<T...> const & x) { return {x};}
+
+  template<int pos, typename TU> auto get(_triqs_reversed_tuple<TU> const & t) DECL_AND_RETURN(std::get<std::tuple_size<typename std::remove_reference<TU>::type>::value-1-pos>(t._x));
+  template<int pos, typename TU> auto get(_triqs_reversed_tuple<TU> & t)       DECL_AND_RETURN(std::get<std::tuple_size<typename std::remove_reference<TU>::type>::value-1-pos>(t._x));
+  template<int pos, typename TU> auto get(_triqs_reversed_tuple<TU> && t)      DECL_AND_RETURN(std::get<std::tuple_size<typename std::remove_reference<TU>::type>::value-1-pos>(move(t)._x));
+
+  template<typename TU> struct tuple_size<_triqs_reversed_tuple<TU>>         : tuple_size<typename std::remove_reference<TU>::type>{};
+}
+
 namespace triqs { namespace tuple {
 
  /**
@@ -42,7 +58,7 @@ namespace triqs { namespace tuple {
  template<typename T, typename X>
   auto push_front(T && t, X &&x) DECL_AND_RETURN ( std::tuple_cat(std::make_tuple(std::forward<X>(x)),std::forward<T>(t)));
 
-/**
+ /**
   * apply(f, t)
   * f : a callable object
   * t a tuple
@@ -225,7 +241,7 @@ namespace triqs { namespace tuple {
   * fold(f, t1, init)
   * f : a callable object
   * t a tuple
-  * Returns : f(x0,f(x1,f(....)) on the tuple
+  * Returns : f(xN,f(x_N-1,...f(x0,r)) on the tuple
   */
  template<int N, int pos, typename T> struct fold_impl {
   template<typename F, typename R>
@@ -291,7 +307,7 @@ namespace triqs { namespace tuple {
 
  template<typename Tu,int ...I> using filter_t = typename filter_t_tr<Tu,I...>::type;
 
-/** 
+ /** 
   * filter_out<int ... I>(t) : 
   *  Given a tuple t, and integers, returns the tuple where the elements at initial position I are dropped.
   */
@@ -433,10 +449,5 @@ namespace std {
  }
 }
 
-
-
-
-
-
 #endif