/** * The physical length library. Made for nanometer scale. * @file length.h */ /* sorry it is not styled correctly, i'll work on it further */ #ifndef LENGTH_H_INCLUDED #define LENGTH_H_INCLUDED 1 /* type to be used by length units by default */ typedef int DEF_LENGTH_VALUE; /** * Length template class * @param T actual type holding a value (be aware of precision and range!) * @param P power of length unit: 1 - length, 2 - area, 3 - volume, -1 - lin. density etc... * This class check length dimension in compile time. In runtime it behaves * exactly like contained type t (which should be numeric type, like int or double) * This class can be replaced with its contained type or simple stub. * Check rules: * - comparisons (< = etc.), addition, subtraction require values of same dimension * e. g. length with length, area with area etc. * - multiplication and division result have appropriate dimension (powers * added and subtracted respectively) * - sqrt and cbrt have appropriate dimensions (P/2 and P/3). * Limitations: * - functions which should not be applied to dimensioned values are not implemeted: * they include algebraic (exp, log...), trigo (sin, cos...), hyperbolic (sinh, cosh..) * - pow function is not implemented as it is require dimension check in runtime * you should use multiplication, division, sqrt and cbrt functions instead. * - sqrt and cbrt result type should be instantiated before they used * Be aware when using them in complex formulae, e. g. * LENGTH< double, 1 > len = cbrt(vol) - is ok, but * LENGTH< double, 2 > vol = sqrt(area*area*area*area)/length - will fail * if LENGTH<..., 4> is not instantiated * - non-integer power values do not supported * they should be implemented carefully using natural fractions, not floats, to be exact * but they are very rare so you should not worry about. * e. g. linear electric noise density should be in mV/sqrt(m) * - automatic numeric type casts are not performed. You even have to manually * cast LENGTH< short > to LENGTH< int > or LENGTH< float > * to LENGTH< double >. Anyway it is not such trouble as progremmer should be * very careful when mixing numeric types and avoid automatic casts. * */ template < typename T = DEF_LENGTH_VALUE, int P = 1 > class LENGTH; /** * Length units contained in this class */ template <typename T> class LENGTH_UNITS; /** * For internal needs */ template < typename T, int P > struct LENGTH_TRAITS { typedef LENGTH<T, P> flat; }; template < typename T > struct LENGTH_TRAITS< T, 0 > { /* length dimension to power 0 is just a number, so LENGTH<T, 0> should be automatically converted to T */ typedef T flat; }; template < typename T, int P > class LENGTH { friend class LENGTH_UNITS< T >; friend class LENGTH_TRAITS< T, P >; template < typename Y, int R > friend class LENGTH; protected: T m_U; LENGTH( T units ) : m_U( units ) { } static T RawValue( const LENGTH<T, P> &x ) { return x.m_U; } static T RawValue( const T& x ) { return x; } public: typedef T value_type; enum { dimension = P }; LENGTH( const LENGTH <T, P> &orig ) : m_U( orig.m_U ) { } LENGTH( void ) : m_U() { } static LENGTH<T, P> zero ( void ) { return T(0); } LENGTH<T, P> & operator = ( const LENGTH<T, P> & y ) { this->m_U = y.m_U; return *this; } template <typename Y> operator LENGTH< Y, P > ( void ) { return this->m_U; } /*************************/ /* comparisons and tests */ /*************************/ bool operator ==( const LENGTH < T, P > y ) const { return m_U == y.m_U; } bool operator !=( const LENGTH < T, P > y ) const { return m_U != y.m_U; } bool operator <( const LENGTH < T, P > y ) const { return m_U < y.m_U; } bool operator >=( const LENGTH < T, P > y ) const { return m_U >= y.m_U; } bool operator >( const LENGTH < T, P > y ) const { return m_U > y.m_U; } bool operator <=( const LENGTH < T, P > y ) const { return m_U <= y.m_U; } bool operator !( void ) const { return !m_U; } /*************************/ /* basic arithmetic */ /*************************/ LENGTH< T, P > operator - ( void ) const { return LENGTH<T, P>(-this->m_U); } LENGTH< T, P > operator - ( const LENGTH< T, P > y ) const { return m_U - y.m_U; } LENGTH< T, P > operator + ( const LENGTH< T, P > y ) const { return m_U + y.m_U; } template < int R > typename LENGTH_TRAITS< T, P + R >::flat operator * ( const LENGTH<T, R> &y ) const { return m_U * y.m_U; } LENGTH< T, P > operator * ( const T & y) const { return m_U * y; } LENGTH< T, P > friend operator * ( const T &y, const LENGTH<T, P> &x ) { return x.m_U * y; } template < int R > typename LENGTH_TRAITS< T, P - R >::flat operator / ( const LENGTH<T, R> &y ) const { return m_U / y.m_U; } LENGTH< T, P > operator / ( const T &y ) const { return m_U / y; } LENGTH< T, -P > friend operator / ( const T &y, const LENGTH< T, P > &x ) { return y / x.m_U; } friend LENGTH< T, P > sqrt( LENGTH< T, P*2 > y ) { return sqrt( y.m_U ); } friend LENGTH< T, P > cbrt( LENGTH< T, P*3 > y ) { return cbrt( y.m_U ); } /*************************/ /* assignment arithmetic */ /*************************/ LENGTH< T, P >& operator -= ( const LENGTH< T, P > y ) { return m_U -= y.m_U; } LENGTH< T, P >& operator += ( const LENGTH< T, P > y ) { return m_U += y.m_U; } LENGTH< T, P >& operator *= ( const T y ) { return m_U *= y; } LENGTH< T, P >& operator /= ( const T y ) { return m_U /= y; } /*************************/ /* more arithmetic */ /*************************/ }; /** * Units of length * * How to use them: * there are several functions, named LENGTH_UNITS< T >::METRE, which return * named unit (1 meter in example) which have type LENGTH< T, P >. * to get specific length you should use a multiplication: * 3*LENGTH_UNITS::metre() gives 3 metres * 0.01*LENGTH_UNITS::metre() gives 0.01 inch * to get numeric value of length in specific units you should use a division * length/LENGTH_UNITS::metre() gives number of metres in length * legnth/LENGTH_UNITS::foot() gives number of feet in length */ template < typename T = DEF_LENGTH_VALUE > class LENGTH_UNITS { protected: enum { METRE = 1000000000, /* The ONLY constant connecting length to the real world */ INCH = METRE / 10000 * 254 }; public: static LENGTH< T, 1 > metre( void ) { return T( METRE ); } static LENGTH< T, 1 > decimetre( void ) { return T( METRE / 10 ); } static LENGTH< T, 1 > centimetre( void ) { return T( METRE / 100 ); } static LENGTH< T, 1 > millimetre( void ) { return T( METRE / 1000 ); } static LENGTH< T, 1 > micrometre( void ) { return T( METRE / 1000000 ); } static LENGTH< T, 1 > foot( void ) { /* do not think this will ever need */ return T( INCH * 12 ); } static LENGTH< T, 1 > inch( void ) { return T( INCH ); } static LENGTH< T, 1 > mil( void ) { return T( INCH / 1000 ); } }; /** * shortcut to get units of given length type */ template < typename T, int D > class LENGTH_UNITS< LENGTH< T, D > >: public LENGTH_UNITS< T > { }; #endif