284 lines
8.0 KiB
C++
284 lines
8.0 KiB
C++
// A very small replacement for boost::tuple
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// (c) Alexander Gessler, 2008 [alexander.gessler@gmx.net]
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#ifndef BOOST_TUPLE_INCLUDED
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#define BOOST_TUPLE_INCLUDED
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namespace boost {
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namespace detail {
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// Represents an empty tuple slot (up to 5 supported)
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struct nulltype {};
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// For readable error messages
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struct tuple_component_idx_out_of_bounds;
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// To share some code for the const/nonconst versions of the getters
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template <bool b, typename T>
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struct ConstIf {
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typedef T t;
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};
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template <typename T>
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struct ConstIf<true,T> {
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typedef const T t;
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};
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// Predeclare some stuff
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template <typename, unsigned, typename, bool, unsigned> struct value_getter;
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// Helper to obtain the type of a tuple element
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template <typename T, unsigned NIDX, typename TNEXT, unsigned N /*= 0*/>
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struct type_getter {
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typedef type_getter<typename TNEXT::type,NIDX+1,typename TNEXT::next_type,N> next_elem_getter;
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typedef typename next_elem_getter::type type;
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};
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template <typename T, unsigned NIDX, typename TNEXT >
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struct type_getter <T,NIDX,TNEXT,NIDX> {
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typedef T type;
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};
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// Base class for all explicit specializations of list_elem
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template <typename T, unsigned NIDX, typename TNEXT >
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struct list_elem_base {
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// Store template parameters
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typedef TNEXT next_type;
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typedef T type;
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static const unsigned nidx = NIDX;
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};
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// Represents an element in the tuple component list
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template <typename T, unsigned NIDX, typename TNEXT >
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struct list_elem : list_elem_base<T,NIDX,TNEXT>{
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// Real members
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T me;
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TNEXT next;
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// Get the value of a specific tuple element
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template <unsigned N>
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typename type_getter<T,NIDX,TNEXT,N>::type& get () {
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value_getter <T,NIDX,TNEXT,false,N> s;
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return s(*this);
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}
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// Get the value of a specific tuple element
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template <unsigned N>
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const typename type_getter<T,NIDX,TNEXT,N>::type& get () const {
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value_getter <T,NIDX,TNEXT,true,N> s;
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return s(*this);
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}
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// Explicit cast
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template <typename T2, typename TNEXT2 >
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operator list_elem<T2,NIDX,TNEXT2> () const {
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list_elem<T2,NIDX,TNEXT2> ret;
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ret.me = (T2)me;
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ret.next = next;
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return ret;
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}
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// Recursively compare two elements (last element returns always true)
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bool operator == (const list_elem& s) const {
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return (me == s.me && next == s.next);
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}
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};
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// Represents a non-used tuple element - the very last element processed
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template <typename TNEXT, unsigned NIDX >
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struct list_elem<nulltype,NIDX,TNEXT> : list_elem_base<nulltype,NIDX,TNEXT> {
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template <unsigned N, bool IS_CONST = true> struct value_getter {
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/* just dummy members to produce readable error messages */
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tuple_component_idx_out_of_bounds operator () (typename ConstIf<IS_CONST,list_elem>::t& me);
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};
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template <unsigned N> struct type_getter {
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/* just dummy members to produce readable error messages */
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typedef tuple_component_idx_out_of_bounds type;
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};
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// dummy
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list_elem& operator = (const list_elem& other) {
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return *this;
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}
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// dummy
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bool operator == (const list_elem& other) {
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return true;
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}
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};
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// Represents the absolute end of the list
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typedef list_elem<nulltype,0,int> list_end;
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// Helper obtain to query the value of a tuple element
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// NOTE: This can't be a nested class as the compiler won't accept a full or
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// partial specialization of a nested class of a non-specialized template
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template <typename T, unsigned NIDX, typename TNEXT, bool IS_CONST, unsigned N>
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struct value_getter {
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// calling list_elem
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typedef list_elem<T,NIDX,TNEXT> outer_elem;
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// typedef for the getter for next element
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typedef value_getter<typename TNEXT::type,NIDX+1,typename TNEXT::next_type,
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IS_CONST, N> next_value_getter;
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typename ConstIf<IS_CONST,typename type_getter<T,NIDX,TNEXT,N>::type>::t&
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operator () (typename ConstIf<IS_CONST,outer_elem >::t& me) {
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next_value_getter s;
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return s(me.next);
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}
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};
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template <typename T, unsigned NIDX, typename TNEXT, bool IS_CONST>
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struct value_getter <T,NIDX,TNEXT,IS_CONST,NIDX> {
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typedef list_elem<T,NIDX,TNEXT> outer_elem;
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typename ConstIf<IS_CONST,T>::t& operator () (typename ConstIf<IS_CONST,outer_elem >::t& me) {
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return me.me;
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}
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};
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};
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// A very minimal implementation for up to 5 elements
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template <typename T0 = detail::nulltype,
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typename T1 = detail::nulltype,
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typename T2 = detail::nulltype,
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typename T3 = detail::nulltype,
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typename T4 = detail::nulltype>
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class tuple {
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template <typename T0b,
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typename T1b,
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typename T2b,
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typename T3b,
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typename T4b >
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friend class tuple;
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private:
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typedef detail::list_elem<T0,0,
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detail::list_elem<T1,1,
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detail::list_elem<T2,2,
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detail::list_elem<T3,3,
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detail::list_elem<T4,4,
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detail::list_end > > > > > very_long;
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very_long m;
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public:
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// Get a specific tuple element
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template <unsigned N>
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typename detail::type_getter<T0,0,typename very_long::next_type, N>::type& get () {
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return m.template get<N>();
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}
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// ... and the const version
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template <unsigned N>
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const typename detail::type_getter<T0,0,typename very_long::next_type, N>::type& get () const {
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return m.get<N>();
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}
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// comparison operators
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bool operator== (const tuple& other) const {
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return m == other.m;
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}
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// ... and the other way round
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bool operator!= (const tuple& other) const {
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return !(m == other.m);
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}
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// cast to another tuple - all single elements must be convertible
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template <typename T0b, typename T1b,typename T2b,typename T3b, typename T4b>
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operator tuple <T0b,T1b,T2b,T3b,T4b> () const {
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tuple <T0b,T1b,T2b,T3b,T4b> s;
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s.m = (typename tuple <T0b,T1b,T2b,T3b,T4b>::very_long)m;
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return s;
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}
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};
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// Another way to access an element ...
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template <unsigned N,typename T0,typename T1,typename T2,typename T3,typename T4>
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inline typename tuple<T0,T1,T2,T3,T4>::very_long::template type_getter<N>::type& get (
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tuple<T0,T1,T2,T3,T4>& m) {
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return m.get<N>();
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}
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// ... and the const version
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template <unsigned N,typename T0,typename T1,typename T2,typename T3,typename T4>
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inline const typename tuple<T0,T1,T2,T3,T4>::very_long::template type_getter<N>::type& get (
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const tuple<T0,T1,T2,T3,T4>& m) {
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return m.get<N>();
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}
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// Constructs a tuple with 5 elements
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template <typename T0,typename T1,typename T2,typename T3,typename T4>
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inline tuple <T0,T1,T2,T3,T4> make_tuple (const T0& t0,
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const T1& t1,const T2& t2,const T3& t3,const T4& t4) {
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tuple <T0,T1,T2,T3,T4> t;
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t.get<0>() = t0;
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t.get<1>() = t1;
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t.get<2>() = t2;
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t.get<3>() = t3;
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t.get<4>() = t4;
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return t;
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}
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// Constructs a tuple with 4 elements
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template <typename T0,typename T1,typename T2,typename T3>
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inline tuple <T0,T1,T2,T3> make_tuple (const T0& t0,
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const T1& t1,const T2& t2,const T3& t3) {
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tuple <T0,T1,T2,T3> t;
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t.get<0>() = t0;
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t.get<1>() = t1;
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t.get<2>() = t2;
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t.get<3>() = t3;
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return t;
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}
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// Constructs a tuple with 3 elements
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template <typename T0,typename T1,typename T2>
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inline tuple <T0,T1,T2> make_tuple (const T0& t0,
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const T1& t1,const T2& t2) {
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tuple <T0,T1,T2> t;
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t.get<0>() = t0;
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t.get<1>() = t1;
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t.get<2>() = t2;
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return t;
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}
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// Constructs a tuple with 2 elements
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template <typename T0,typename T1>
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inline tuple <T0,T1> make_tuple (const T0& t0,
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const T1& t1) {
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tuple <T0,T1> t;
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t.get<0>() = t0;
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t.get<1>() = t1;
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return t;
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}
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// Constructs a tuple with 1 elements (well ...)
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template <typename T0>
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inline tuple <T0> make_tuple (const T0& t0) {
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tuple <T0> t;
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t.get<0>() = t0;
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return t;
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}
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// Constructs a tuple with 0 elements (well ...)
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inline tuple <> make_tuple () {
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tuple <> t;
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return t;
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}
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};
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#endif // !! BOOST_TUPLE_INCLUDED
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