variadic-tuple.c

来自「用于进行gcc测试」· C语言 代码 · 共 295 行

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// { dg-options "-std=gnu++0x" }// { dg-do "run" }// An implementation of TR1's <tuple> using variadic teplates// Contributed by Douglas Gregor <doug.gregor@gmail.com>#include <string>#include <cassert>#include <cstring>// Trivial reference_wrappertemplate<typename T>struct reference_wrapper{  reference_wrapper(T& x) : ptr(&x) { }  operator T&() const { return *ptr; }  T* ptr;};template<typename T> reference_wrapper<T> ref(T& x) { return x; }template<typename T> reference_wrapper<const T> cref(const T& x) { return x; }// Simple type-traits we'll needtemplate<typename T>struct add_reference{  typedef T& type;};template<typename T>struct add_reference<T&>{  typedef T& type;};template<typename T, typename U>struct is_same{  static const bool value = false;};template<typename T>struct is_same<T, T>{  static const bool value = true;};// For creating the constructor parameters of tuple<>template<typename T>struct add_const_reference{  typedef const T& type;};template<typename T>struct add_const_reference<T&>{  typedef T& type;};// 6.1.3 Class template tuple template<typename... Values>class tuple;template<> class tuple<> { };template<typename Head, typename... Tail>class tuple<Head, Tail...>   : private tuple<Tail...>{  typedef tuple<Tail...> inherited; public:  tuple() { }  // implicit copy-constructor is okay  tuple(typename add_const_reference<Head>::type v,         typename add_const_reference<Tail>::type... vtail)    : m_head(v), inherited(vtail...) { }  template<typename... VValues>  tuple(const tuple<VValues...>& other)    : m_head(other.head()), inherited(other.tail()) { }  template<typename... VValues>  tuple& operator=(const tuple<VValues...>& other)  {    m_head = other.head();    tail() = other.tail();    return *this;  }  typename add_reference<Head>::type       head()       { return m_head; }  typename add_reference<const Head>::type head() const { return m_head; }  inherited&                               tail()       { return *this; }  const inherited&                         tail() const { return *this; } protected:  Head m_head;};template<typename T>struct make_tuple_result{  typedef T type;};template<typename T>struct make_tuple_result<reference_wrapper<T> >{  typedef T& type;};// 6.1.3.2 Tuple creation functionsstruct ignore_t {   template<typename T> ignore_t& operator=(const T&) { return *this; }} ignore;template<typename... Values>tuple<typename make_tuple_result<Values>::type...> make_tuple(const Values&... values){  return tuple<typename make_tuple_result<Values>::type...>(values...);}template<typename... Values>tuple<Values&...> tie(Values&... values){  return tuple<Values&...>(values...);}// 6.1.3.3 Tuple helper classestemplate<typename Tuple>struct tuple_size;template<>struct tuple_size<tuple<> >{  static const std::size_t value = 0;};template<typename Head, typename... Tail>struct tuple_size<tuple<Head, Tail...> >{  static const std::size_t value = 1 + tuple_size<tuple<Tail...> >::value;};template<int I, typename Tuple>struct tuple_element;template<int I, typename Head, typename... Tail>struct tuple_element<I, tuple<Head, Tail...> >{  typedef typename tuple_element<I-1, tuple<Tail...> >::type type;};template<typename Head, typename... Tail>struct tuple_element<0, tuple<Head, Tail...> >{  typedef Head type;};// 6.1.3.4 Element accesstemplate<int I, typename Tuple>class get_impl;template<int I, typename Head, typename... Values> class get_impl<I, tuple<Head, Values...> >{  typedef typename tuple_element<I-1, tuple<Values...> >::type Element;  typedef typename add_reference<Element>::type RJ;  typedef typename add_const_reference<Element>::type PJ;  typedef get_impl<I-1, tuple<Values...> > Next; public:  static RJ get(tuple<Head, Values...>& t)         { return Next::get(t.tail()); }  static PJ get(const tuple<Head, Values...>& t)   { return Next::get(t.tail()); }};template<typename Head, typename... Values> class get_impl<0, tuple<Head, Values...> >{  typedef typename add_reference<Head>::type RJ;  typedef typename add_const_reference<Head>::type PJ; public:  static RJ get(tuple<Head, Values...>& t)       { return t.head(); }  static PJ get(const tuple<Head, Values...>& t) { return t.head(); }};template<int I, typename... Values>typename add_reference<           typename tuple_element<I, tuple<Values...> >::type         >::typeget(tuple<Values...>& t){  return get_impl<I, tuple<Values...> >::get(t);}template<int I, typename... Values>typename add_const_reference<           typename tuple_element<I, tuple<Values...> >::type         >::typeget(const tuple<Values...>& t){  return get_impl<I, tuple<Values...> >::get(t);}// 6.1.3.5 Relational operatorsinline bool operator==(const tuple<>&, const tuple<>&) { return true; }template<typename T, typename... TTail, typename U, typename... UTail>bool operator==(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u){  return t.head() == u.head() && t.tail() == u.tail();}template<typename... TValues, typename... UValues>bool operator!=(const tuple<TValues...>& t, const tuple<UValues...>& u){  return !(t == u);}inline bool operator<(const tuple<>&, const tuple<>&) { return false; }template<typename T, typename... TTail, typename U, typename... UTail>bool operator<(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u){  return (t.head() < u.head() ||           (!(t.head() < u.head()) && t.tail() < u.tail()));}template<typename... TValues, typename... UValues>bool operator>(const tuple<TValues...>& t, const tuple<UValues...>& u){  return u < t;}template<typename... TValues, typename... UValues>bool operator<=(const tuple<TValues...>& t, const tuple<UValues...>& u){  return !(u < t);}template<typename... TValues, typename... UValues>bool operator>=(const tuple<TValues...>& t, const tuple<UValues...>& u){  return !(t < u);}int a0[tuple_size<tuple<> >::value == 0? 1 : -1];int a1[tuple_size<tuple<int, float, double> >::value == 3? 1 : -1];int a2a[is_same<tuple_element<0, tuple<int, float, double> >::type, int>         ::value? 1 : -1];int a2b[is_same<tuple_element<1, tuple<int, float, double> >::type, float>         ::value? 1 : -1];int a2c[is_same<tuple_element<2, tuple<int, float, double> >::type, double>         ::value? 1 : -1];int main(){  tuple<> t0;  tuple<int> t1(1);  tuple<int, float> t2(1, 3.14159f);  tuple<int, float, const char*> t3a(1, 3.14159f, "Hello, world!");  tuple<long, double, std::string> t3b(t3a);  t3b = t3a;  //  t3a = t3b; DPG: triggers an error, as it should.  tuple<int, float, std::string> t3c =     make_tuple(17, 2.718281828, std::string("Fun"));  int seventeen = 17;  double pi = 3.14159;  tuple<int&, double&> seventeen_pi = make_tuple(ref(seventeen), ref(pi));  tuple<int&, const double&> seventeen_pi2 =     make_tuple(ref(seventeen), cref(pi));  tuple<int&, double&> seventeen_pi_tied = tie(seventeen, pi);  assert(get<0>(t3a) == 1);  assert(get<1>(t3a) == 3.14159f);  assert(std::strcmp(get<2>(t3a), "Hello, world!") == 0);  assert(t3a == t3b);  assert(!(t3a != t3b));  assert(!(t3a < t3b));  assert(!(t3a > t3b));  assert(t3a <= t3b && t3b <= t3a);  assert(t3a >= t3b && t3b >= t3a);}

variadic-tuple.c - 源码说明

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