Pair.H

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License
    This file is part of OpenFOAM.
 
    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.
 
    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
Class
    Foam::Pair
 
Description
    An ordered pair of two objects of type <Type> with first() and second()
    elements.
 
See also
    Foam::Tuple2 for storing two objects of dissimilar types.
 
\*---------------------------------------------------------------------------*/
 
#ifndef Pair_H
#define Pair_H
 
#include "Hash.H"
#include "scaleable.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
 
// Forward declaration of friend functions and operators
 
template<class Type>
class Pair;
 
template<class Type>
void writeEntry(Ostream& os, const Pair<Type>&);
 
template<class Type>
inline Istream& operator>>(Istream&, Pair<Type>&);
 
template<class Type>
inline Ostream& operator<<(Ostream&, const Pair<Type>&);
 
 
/*---------------------------------------------------------------------------*\
                            Class Pair Declaration
\*---------------------------------------------------------------------------*/
 
template<class Type>
class Pair
{
    // Private Data
 
        //- First object
        Type f_;
 
        //- Second object
        Type s_;
 
 
public:
 
    // Public Sub-Classes
 
        //- Hashing function class
        template<class HashT=Hash<Type>>
        class Hash
        {
        public:
 
            // Constructors
 
                //- Null constructor
                inline Hash();
 
 
            // Member Operators
 
                //- Hash a pair
                inline unsigned operator()
                (
                    const Pair<Type>& p,
                    unsigned seed = 0
                ) const;
        };
 
 
    // Static Member Functions
 
        //- Return a null pair
        static inline const Pair<Type>& null();
 
        //- Return the size
        static inline label size();
 
        //- Check index i is within valid range (0 ... 1)
        static inline void checkIndex(const label i);
 
        //- Compare two pairs. Return 0 if they are different, +1 if they are
        //  identical, and -1 if the elements are the same but reversed.
        static inline int compare(const Pair<Type>& a, const Pair<Type>& b);
 
 
    // Constructors
 
        //- Null constructor
        inline Pair();
 
        //- Construct from components
        inline Pair(const Type& f, const Type& s);
 
        //- Construct from Istream
        inline Pair(Istream& is);
 
 
    // Member Functions
 
        //- Return first
        inline const Type& first() const;
 
        //- Return first
        inline Type& first();
 
        //- Return second
        inline const Type& second() const;
 
        //- Return second
        inline Type& second();
 
        //- Return other
        inline const Type& other(const Type& a) const;
 
 
    // Member Operators
 
        //- Access an element by index
        inline Type& operator[](const label i);
 
        //- Const-access an element by index
        inline const Type& operator[](const label i) const;
 
 
    // STL type definitions
 
        //- Type of values the pair contains
        typedef Type value_type;
 
        //- Type that can be used for storing into
        //  pair::value_type objects
        typedef Type& reference;
 
        //- Type that can be used for storing into
        //  constant pair::value_type objects
        typedef const Type& const_reference;
};
 
 
// Global Functions
 
//- Reverse the elements in a pair
template<class Type>
inline Pair<Type> reverse(const Pair<Type>& p);
 
//- Equality comparison
template<class Type>
inline bool operator==(const Pair<Type>& a, const Pair<Type>& b);
 
//- Inequality comparison
template<class Type>
inline bool operator!=(const Pair<Type>& a, const Pair<Type>& b);
 
//- Compare lexographic order
template<class Type>
inline bool operator<(const Pair<Type>& a, const Pair<Type>& b);
 
//- Compare lexographic order
template<class Type>
inline bool operator<=(const Pair<Type>& a, const Pair<Type>& b);
 
//- Compare lexographic order
template<class Type>
inline bool operator>(const Pair<Type>& a, const Pair<Type>& b);
 
//- Compare lexographic order
template<class Type>
inline bool operator>=(const Pair<Type>& a, const Pair<Type>& b);
 
//- Read a from a stream
template<class Type>
inline Istream& operator>>(Istream& is, Pair<Type>& p);
 
//- Write to a stream
template<class Type>
inline Ostream& operator<<(Ostream& os, const Pair<Type>& p);
 
//- Write as a dictionary entry
template<class Type>
inline void writeEntry(Ostream& os, const Pair<Type>& p);
 
 
//- A pair is scaleable if its type is
template<class Type>
struct scaleable<Pair<Type>> : public scaleable<Type> {};
 
//- Apply a conversion to a Pair by applying separately to first and second
template<class Type, class ... Args>
void convert(Pair<Type>& t, const Args& ... args)
{
    convert(t.first(), args ...);
    convert(t.second(), args ...);
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#include "PairI.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //