Files
boost_tuple/include/boost/tuple/detail/tuple_basic.hpp
Jaakko Järvi adeeed1f6d Adding the Tuple library files
[SVN r10828]
2001-08-10 11:45:43 +00:00

708 lines
23 KiB
C++

// tuple_basic.hpp -----------------------------------------------------
// Copyright (C) 1999, 2000 Jaakko Järvi (jaakko.jarvi@cs.utu.fi)
//
// Permission to copy, use, sell and distribute this software is granted
// provided this copyright notice appears in all copies.
// Permission to modify the code and to distribute modified code is granted
// provided this copyright notice appears in all copies, and a notice
// that the code was modified is included with the copyright notice.
//
// This software is provided "as is" without express or implied warranty,
// and with no claim as to its suitability for any purpose.
// For more information, see http://www.boost.org
// Outside help:
// This and that, Gary Powell.
// Fixed return types for get_head/get_tail
// ( and other bugs ) per suggestion of Jens Maurer
// simplified element type accessors + bug fix (Jeremy Siek)
// Several changes/additions according to suggestions by Doug Gregor,
// William Kempf, Vesa Karvonen, John Max Skaller, Ed Brey, Beman Davis,
// David Abrahams.
// -----------------------------------------------------------------
#ifndef BOOST_TUPLE_BASIC_HPP
#define BOOST_TUPLE_BASIC_HPP
#include <utility> // needed for the assignment from pair to tuple
#include "boost/type_traits/cv_traits.hpp"
namespace boost {
// -- null_type --------------------------------------------------------
struct null_type {};
// a helper function to provide a const null_type type temporary
namespace detail {
namespace tuples {
inline const null_type cnull_type() { return null_type(); }
} // end tuples
} // end detail
// - cons forward declaration -----------------------------------------------
template <class HT, class TT>
struct cons;
// - tuple forward declaration -----------------------------------------------
template <
class T0 = null_type, class T1 = null_type, class T2 = null_type,
class T3 = null_type, class T4 = null_type, class T5 = null_type,
class T6 = null_type, class T7 = null_type, class T8 = null_type,
class T9 = null_type>
class tuple;
// tuple_length forward declaration
template<class T> struct tuple_length;
namespace detail {
namespace tuples {
// -- generate error template, referencing to non-existing members of this
// template is used to produce compilation errors intentionally
template<class T>
class generate_error;
// tuple default argument wrappers ---------------------------------------
// Work for non-reference types, intentionally not for references
template <class T>
struct default_arg {
// Non-class temporaries cannot have qualifiers.
// To prevent f to return for example const int, we remove cv-qualifiers
// from all temporaries.
static typename boost::remove_cv<T>::type f() { return T(); }
};
template <class T>
struct default_arg<T&> {
static T& f() {
return generate_error<T>::no_default_values_for_reference_types;
}
};
// - cons getters --------------------------------------------------------
// called: element<N>::get<RETURN_TYPE>(aTuple)
template< int N >
struct element {
template<class RET, class HT, class TT >
inline static RET get(const cons<HT, TT>& t)
{
return element<N-1>::template get<RET>(t.tail);
}
template<class RET, class HT, class TT >
inline static RET get(cons<HT, TT>& t)
{
return element<N-1>::template get<RET>(t.tail);
}
};
template<>
struct element<0> {
template<class RET, class HT, class TT>
inline static RET get(const cons<HT, TT>& t)
{
return t.head;
}
template<class RET, class HT, class TT>
inline static RET get(cons<HT, TT>& t)
{
return t.head;
}
};
} // end of namespace tuples
} // end of namespace detail
// -cons type accessors ----------------------------------------
// typename tuple_element<N,T>::type gets the type of the
// Nth element ot T, first element is at index 0
// -------------------------------------------------------
template<int N, class T>
struct tuple_element
{
private:
typedef typename T::tail_type Next;
public:
typedef typename tuple_element<N-1, Next>::type type;
};
template<class T>
struct tuple_element<0,T>
{
typedef typename T::head_type type;
};
// -get function templates -----------------------------------------------
// Usage: get<N>(aTuple)
// -- some traits classes for get functions
// access traits lifted from detail namespace to be part of the interface,
// (Joel de Guzman's suggestion). Rationale: get functions are part of the
// interface, so should the way to express their return types be.
template <class T> struct tuple_access_traits {
typedef const T& const_type;
typedef T& non_const_type;
typedef const typename boost::remove_cv<T>::type& parameter_type;
// used as the tuple constructors parameter types
// Rationale: non-reference tuple element types can be cv-qualified.
// It should be possible to initialize such types with temporaries,
// and when binding temporaries to references, the reference must
// be non-volatile and const. 8.5.3. (5)
};
template <class T> struct tuple_access_traits<T&> {
typedef T& const_type;
typedef T& non_const_type;
typedef T& parameter_type;
};
// get function for non-const cons-lists, returns a reference to the element
template<int N, class HT, class TT>
inline typename tuple_access_traits<
typename tuple_element<N, cons<HT, TT> >::type
>::non_const_type
get(cons<HT, TT>& c) {
return detail::tuples::element<N>::template
get<
typename tuple_access_traits<
typename tuple_element<N, cons<HT, TT> >::type
>::non_const_type>(c);
}
// get function for const cons-lists, returns a const reference to
// the element. If the element is a reference, returns the reference
// as such (that is, can return a non-const reference)
template<int N, class HT, class TT>
inline typename tuple_access_traits<
typename tuple_element<N, cons<HT, TT> >::type
>::const_type
get(const cons<HT, TT>& c) {
return detail::tuples::element<N>::template
get<
typename tuple_access_traits<
typename tuple_element<N, cons<HT, TT> >::type
>::const_type>(c);
}
// -- the cons template --------------------------------------------------
template <class HT, class TT>
struct cons {
typedef HT head_type;
typedef TT tail_type;
head_type head;
tail_type tail;
typename tuple_access_traits<head_type>::non_const_type get_head() { return head; }
typename tuple_access_traits<tail_type>::non_const_type get_tail() { return tail; }
typename tuple_access_traits<head_type>::const_type get_head() const { return head; }
typename tuple_access_traits<tail_type>::const_type get_tail() const { return tail; }
template <class T1, class T2, class T3, class T4, class T5,
class T6, class T7, class T8, class T9, class T10>
cons( T1& t1, T2& t2, T3& t3, T4& t4, T5& t5,
T6& t6, T7& t7, T8& t8, T9& t9, T10& t10 )
: head (t1) , tail (t2, t3, t4, t5, t6, t7, t8, t9, t10, detail::tuples::cnull_type()) {}
template <class HT2, class TT2>
cons( const cons<HT2, TT2>& u ) : head(u.head), tail(u.tail) {}
template <class HT2, class TT2>
cons& operator=( const cons<HT2, TT2>& u ) {
head=u.head; tail=u.tail; return *this;
}
// must define assignment operator explicitly, implicit version is
// illformed if HT is a reference (12.8. (12))
cons& operator=(const cons& u) {
head = u.head; tail = u.tail; return *this;
}
template <class T1, class T2>
cons& operator=( const std::pair<T1, T2>& u ) {
BOOST_STATIC_ASSERT(tuple_length<cons>::value == 2); // check length = 2
head = u.first; tail.head = u.second; return *this;
}
// get member functions (non-const and const)
template <int N>
typename tuple_access_traits<
typename tuple_element<N, cons<HT, TT> >::type
>::non_const_type
get() {
return boost::get<N>(*this); // delegate to non-member get
}
template <int N>
typename tuple_access_traits<
typename tuple_element<N, cons<HT, TT> >::type
>::const_type
get() const {
return boost::get<N>(*this); // delegate to non-member get
}
};
template <class HT>
struct cons<HT, null_type> {
typedef HT head_type;
typedef null_type tail_type;
head_type head;
typename tuple_access_traits<head_type>::non_const_type get_head() { return head; }
null_type get_tail() { return null_type(); }
typename tuple_access_traits<head_type>::const_type get_head() const { return head; }
const null_type get_tail() const { return null_type(); }
template<class T1>
cons( T1& t1, const null_type&, const null_type&, const null_type&, const null_type&,
const null_type&, const null_type&, const null_type&, const null_type&, const null_type&)
: head (t1) {}
template <class HT2>
cons( const cons<HT2, null_type>& u ) : head(u.head) {}
template <class HT2>
cons& operator=(const cons<HT2, null_type>& u ) { head = u.head; return *this; }
// must define assignment operator explicitely, implicit version
// is illformed if HT is a reference
cons& operator=(const cons& u) { head = u.head; return *this; }
template <int N>
typename tuple_access_traits<
typename tuple_element<N, cons>::type
>::non_const_type
get() {
return boost::get<N>(*this);
}
template <int N>
typename tuple_access_traits<
typename tuple_element<N, cons>::type
>::const_type
get() const {
return boost::get<N>(*this);
}
};
// templates for finding out the length of the tuple -------------------
template<class T>
struct tuple_length {
BOOST_STATIC_CONSTANT(int, value = 1 + tuple_length<typename T::tail_type>::value);
};
template<>
struct tuple_length<null_type> {
BOOST_STATIC_CONSTANT(int, value = 0);
};
namespace detail {
namespace tuples {
// Tuple to cons mapper --------------------------------------------------
template <class T0, class T1, class T2, class T3, class T4,
class T5, class T6, class T7, class T8, class T9>
struct map_tuple_to_cons
{
typedef cons<T0,
typename map_tuple_to_cons<T1, T2, T3, T4, T5,
T6, T7, T8, T9, null_type>::type
> type;
};
template <class T0>
struct map_tuple_to_cons<T0, null_type, null_type, null_type, null_type, null_type, null_type, null_type, null_type, null_type>
{
typedef cons<T0, null_type> type;
};
// The empty tuple is a null_type
template <>
struct map_tuple_to_cons<null_type, null_type, null_type, null_type, null_type, null_type, null_type, null_type, null_type, null_type>
{
typedef null_type type;
};
} // end tuples
} // end detail
// -------------------------------------------------------------------
// -- tuple ------------------------------------------------------
template <class T0, class T1, class T2, class T3, class T4,
class T5, class T6, class T7, class T8, class T9>
class tuple :
public detail::tuples::map_tuple_to_cons<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9>::type
{
public:
typedef typename
detail::tuples::map_tuple_to_cons<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9>::type inherited;
typedef typename inherited::head_type head_type;
typedef typename inherited::tail_type tail_type;
// tuple_access_traits<T>::parameter_type takes non-reference types as const T&
explicit tuple(
typename tuple_access_traits<T0>::parameter_type t0
= detail::tuples::default_arg<T0>::f(),
typename tuple_access_traits<T1>::parameter_type t1
= detail::tuples::default_arg<T1>::f(),
typename tuple_access_traits<T2>::parameter_type t2
= detail::tuples::default_arg<T2>::f(),
typename tuple_access_traits<T3>::parameter_type t3
= detail::tuples::default_arg<T3>::f(),
typename tuple_access_traits<T4>::parameter_type t4
= detail::tuples::default_arg<T4>::f(),
typename tuple_access_traits<T5>::parameter_type t5
= detail::tuples::default_arg<T5>::f(),
typename tuple_access_traits<T6>::parameter_type t6
= detail::tuples::default_arg<T6>::f(),
typename tuple_access_traits<T7>::parameter_type t7
= detail::tuples::default_arg<T7>::f(),
typename tuple_access_traits<T8>::parameter_type t8
= detail::tuples::default_arg<T8>::f(),
typename tuple_access_traits<T9>::parameter_type t9
= detail::tuples::default_arg<T9>::f())
: inherited(t0, t1, t2, t3, t4, t5, t6, t7, t8, t9) {}
template<class U1, class U2>
tuple(const cons<U1, U2>& p) : inherited(p) {}
template <class U1, class U2>
tuple& operator=(const cons<U1, U2>& k) {
inherited::operator=(k);
return *this;
}
template <class U1, class U2>
tuple& operator=(const std::pair<U1, U2>& k) {
BOOST_STATIC_ASSERT(tuple_length<tuple>::value == 2);// check_length = 2
this->head = k.first;
this->tail.head = k.second;
return *this;
}
};
// Swallows any assignment (by Doug Gregor)
namespace detail {
namespace tuples {
struct swallow_assign {
template<typename T>
swallow_assign& operator=(const T&) {
return *this;
}
};
} // namespace tuples
} // namespace detail
// "ignore" allows tuple positions to be ignored when using "tie".
namespace {
detail::tuples::swallow_assign ignore;
}
// ---------------------------------------------------------------------------
// The call_traits for make_tuple
// Honours the reference_wrapper class.
// Must be instantiated with plain or const plain types (not with references)
// from template<class T> foo(const T& t) : make_tuple_traits<const T>::type
// from template<class T> foo(T& t) : make_tuple_traits<T>::type
// Conversions:
// T -> T,
// references -> compile_time_error
// reference_wrapper<T> -> T&
// const reference_wrapper<T> -> T&
// array -> const ref array
template<class T>
struct make_tuple_traits {
typedef T type;
// commented away, see below (JJ)
// typedef typename IF<
// boost::is_function<T>::value,
// T&,
// T>::RET type;
};
// The is_function test was there originally for plain function types,
// which can't be stored as such (we must either store them as references or
// pointers). Such a type could be formed if make_tuple was called with a
// reference to a function.
// But this would mean that a const qualified function type was formed in
// the make_tuple function and hence make_tuple can't take a function
// reference as a parameter, and thus T can't be a function type.
// So is_function test was removed.
// (14.8.3. says that type deduction fails if a cv-qualified function type
// is created. (It only applies for the case of explicitly specifying template
// args, though?)) (JJ)
template<class T>
struct make_tuple_traits<T&> {
typedef typename
detail::tuples::generate_error<T&>::
do_not_use_with_reference_type error;
};
// Arrays can't be stored as plain types; convert them to references.
// All arrays are converted to const. This is because make_tuple takes its
// parameters as const T& and thus the knowledge of the potential
// non-constness of actual argument is lost.
template<class T, int n> struct make_tuple_traits <T[n]> {
typedef const T (&type)[n];
};
template<class T, int n>
struct make_tuple_traits<const T[n]> {
typedef const T (&type)[n];
};
template<class T, int n> struct make_tuple_traits<volatile T[n]> {
typedef const volatile T (&type)[n];
};
template<class T, int n>
struct make_tuple_traits<const volatile T[n]> {
typedef const volatile T (&type)[n];
};
template<class T>
struct make_tuple_traits<reference_wrapper<T> >{
typedef T& type;
};
template<class T>
struct make_tuple_traits<const reference_wrapper<T> >{
typedef T& type;
};
namespace detail {
namespace tuples {
// a helper traits to make the make_tuple functions shorter (Vesa Karvonen's
// suggestion)
template <
class T0 = null_type, class T1 = null_type, class T2 = null_type,
class T3 = null_type, class T4 = null_type, class T5 = null_type,
class T6 = null_type, class T7 = null_type, class T8 = null_type,
class T9 = null_type
>
struct make_tuple_mapper {
typedef
tuple<typename make_tuple_traits<T0>::type,
typename make_tuple_traits<T1>::type,
typename make_tuple_traits<T2>::type,
typename make_tuple_traits<T3>::type,
typename make_tuple_traits<T4>::type,
typename make_tuple_traits<T5>::type,
typename make_tuple_traits<T6>::type,
typename make_tuple_traits<T7>::type,
typename make_tuple_traits<T8>::type,
typename make_tuple_traits<T9>::type> type;
};
} // end tuples
} // end detail
// -make_tuple function templates -----------------------------------
//tuple<> inline make_tuple() {
// return tuple<>();
//}
template<class T0>
boost::detail::tuples::make_tuple_mapper<T0>::type
inline make_tuple(const T0& t0) {
return boost::detail::tuples::make_tuple_mapper<T0>::type(t0);
}
template<class T0, class T1>
boost::detail::tuples::make_tuple_mapper<T0, T1>::type
inline make_tuple(const T0& t0, const T1& t1) {
return boost::detail::tuples::make_tuple_mapper<T0, T1>::type(t0, t1);
}
template<class T0, class T1, class T2>
boost::detail::tuples::make_tuple_mapper<T0, T1, T2>::type
inline make_tuple(const T0& t0, const T1& t1, const T2& t2) {
return boost::detail::tuples::make_tuple_mapper<T0, T1, T2>::type(t0, t1, t2);
}
template<class T0, class T1, class T2, class T3>
boost::detail::tuples::make_tuple_mapper<T0, T1, T2, T3>::type
inline make_tuple(const T0& t0, const T1& t1, const T2& t2, const T3& t3) {
return boost::detail::tuples::make_tuple_mapper<T0, T1, T2, T3>::type
(t0, t1, t2, t3);
}
template<class T0, class T1, class T2, class T3, class T4>
boost::detail::tuples::make_tuple_mapper<T0, T1, T2, T3, T4>::type
inline make_tuple(const T0& t0, const T1& t1, const T2& t2, const T3& t3,
const T4& t4) {
return boost::detail::tuples::make_tuple_mapper<T0, T1, T2, T3, T4>::type
(t0, t1, t2, t3, t4);
}
template<class T0, class T1, class T2, class T3, class T4, class T5>
boost::detail::tuples::make_tuple_mapper<T0, T1, T2, T3, T4, T5>::type
inline make_tuple(const T0& t0, const T1& t1, const T2& t2, const T3& t3,
const T4& t4, const T5& t5) {
return boost::detail::tuples::make_tuple_mapper<T0, T1, T2, T3, T4, T5>::type
(t0, t1, t2, t3, t4, t5);
}
template<class T0, class T1, class T2, class T3, class T4, class T5, class T6>
boost::detail::tuples::make_tuple_mapper<T0, T1, T2, T3, T4, T5, T6>::type
inline make_tuple(const T0& t0, const T1& t1, const T2& t2, const T3& t3,
const T4& t4, const T5& t5, const T6& t6) {
return boost::detail::tuples::make_tuple_mapper
<T0, T1, T2, T3, T4, T5, T6>::type
(t0, t1, t2, t3, t4, t5, t6);
}
template<class T0, class T1, class T2, class T3, class T4, class T5, class T6,
class T7>
boost::detail::tuples::make_tuple_mapper<T0, T1, T2, T3, T4, T5, T6, T7>::type
inline make_tuple(const T0& t0, const T1& t1, const T2& t2, const T3& t3,
const T4& t4, const T5& t5, const T6& t6, const T7& t7) {
return boost::detail::tuples::make_tuple_mapper
<T0, T1, T2, T3, T4, T5, T6, T7>::type
(t0, t1, t2, t3, t4, t5, t6, t7);
}
template<class T0, class T1, class T2, class T3, class T4, class T5, class T6,
class T7, class T8>
boost::detail::tuples::make_tuple_mapper
<T0, T1, T2, T3, T4, T5, T6, T7, T8>::type
inline make_tuple(const T0& t0, const T1& t1, const T2& t2, const T3& t3,
const T4& t4, const T5& t5, const T6& t6, const T7& t7,
const T8& t8) {
return boost::detail::tuples::make_tuple_mapper
<T0, T1, T2, T3, T4, T5, T6, T7, T8>::type
(t0, t1, t2, t3, t4, t5, t6, t7, t8);
}
template<class T0, class T1, class T2, class T3, class T4, class T5, class T6,
class T7, class T8, class T9>
boost::detail::tuples::make_tuple_mapper
<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9>::type
inline make_tuple(const T0& t0, const T1& t1, const T2& t2, const T3& t3,
const T4& t4, const T5& t5, const T6& t6, const T7& t7,
const T8& t8, const T9& t9) {
return boost::detail::tuples::make_tuple_mapper
<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9>::type
(t0, t1, t2, t3, t4, t5, t6, t7, t8, t9);
}
// Tie function templates -------------------------------------------------
template<class T1>
tuple<T1&> inline tie(T1& t1) {
return tuple<T1&> (t1);
}
template<class T1, class T2>
tuple<T1&, T2&> inline tie(T1& t1, T2& t2) {
return tuple<T1&, T2&> (t1, t2);
}
template<class T1, class T2, class T3>
tuple<T1&, T2&, T3&> inline tie(T1& t1, T2& t2, T3& t3) {
return tuple<T1&, T2&, T3&> (t1, t2, t3);
}
template<class T1, class T2, class T3, class T4>
tuple<T1&, T2&, T3&, T4&> inline tie(T1& t1, T2& t2, T3& t3, T4& t4) {
return tuple<T1&, T2&, T3&, T4&> (t1, t2, t3, t4);
}
template<class T1, class T2, class T3, class T4, class T5>
tuple<T1&, T2&, T3&, T4&, T5&>
inline tie(T1& t1, T2& t2, T3& t3, T4& t4, T5& t5) {
return tuple<T1&, T2&, T3&, T4&, T5&> (t1, t2, t3, t4, t5);
}
template<class T1, class T2, class T3, class T4, class T5, class T6>
tuple<T1&, T2&, T3&, T4&, T5&, T6&>
inline tie(T1& t1, T2& t2, T3& t3, T4& t4, T5& t5, T6& t6) {
return tuple<T1&, T2&, T3&, T4&, T5&, T6&> (t1, t2, t3, t4, t5, t6);
}
template<class T1, class T2, class T3, class T4, class T5, class T6, class T7>
tuple<T1&, T2&, T3&, T4&, T5&, T6&, T7&>
inline tie(T1& t1, T2& t2, T3& t3, T4& t4, T5& t5, T6& t6, T7& t7) {
return tuple<T1&, T2&, T3&, T4&, T5&, T6&, T7&> (t1, t2, t3, t4, t5, t6, t7);
}
template<class T1, class T2, class T3, class T4, class T5, class T6, class T7,
class T8>
tuple<T1&, T2&, T3&, T4&, T5&, T6&, T7&, T8&>
inline tie(T1& t1, T2& t2, T3& t3, T4& t4, T5& t5, T6& t6, T7& t7, T8& t8) {
return tuple<T1&, T2&, T3&, T4&, T5&, T6&, T7&, T8&>
(t1, t2, t3, t4, t5, t6, t7, t8);
}
template<class T1, class T2, class T3, class T4, class T5, class T6, class T7,
class T8, class T9>
tuple<T1&, T2&, T3&, T4&, T5&, T6&, T7&, T8&, T9&>
inline tie(T1& t1, T2& t2, T3& t3, T4& t4, T5& t5, T6& t6, T7& t7, T8& t8,
T9& t9) {
return tuple<T1&, T2&, T3&, T4&, T5&, T6&, T7&, T8&, T9&>
(t1, t2, t3, t4, t5, t6, t7, t8, t9);
}
template<class T1, class T2, class T3, class T4, class T5, class T6, class T7,
class T8, class T9, class T10>
tuple<T1&, T2&, T3&, T4&, T5&, T6&, T7&, T8&, T9&, T10&>
inline tie(T1& t1, T2& t2, T3& t3, T4& t4, T5& t5, T6& t6, T7& t7, T8& t8,
T9& t9, T10& t10) {
return tuple<T1&, T2&, T3&, T4&, T5&, T6&, T7&, T8&, T9&, T10&>
(t1, t2, t3, t4, t5, t6, t7, t8, t9, t10);
}
} // end of namespace boost
#endif // BOOST_TUPLE_BASIC_HPP