UnitDim.h

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// # UnitDim.h: defines the (private) class describing basic SI dimensions
// # Copyright (C) 1994,1995,1996,1997,1999,2000,2001
// # Associated Universities, Inc. Washington DC, USA.
// #
// # This library is free software; you can redistribute it and/or modify it
// # under the terms of the GNU Library General Public License as published by
// # the Free Software Foundation; either version 2 of the License, or (at your
// # option) any later version.
// #
// # This library 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 Library General Public
// # License for more details.
// #
// # You should have received a copy of the GNU Library General Public License
// # along with this library; if not, write to the Free Software Foundation,
// # Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
// #
// # Correspondence concerning AIPS++ should be addressed as follows:
// #        Internet email: casa-feedback@nrao.edu.
// #        Postal address: AIPS++ Project Office
// #                        National Radio Astronomy Observatory
// #                        520 Edgemont Road
// #                        Charlottesville, VA 22903-2475 USA
 
#ifndef CASA_UNITDIM_H
#define CASA_UNITDIM_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/iosfwd.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// # Forward Declarations
class String;
class UnitVal;
class UnitMap;
 
//
// <summary>
// describes a unit in basic SI unit dimensions
// </summary>
 
// <use visibility=local>
 
// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="tUnit">
//
// <prerequisite>
// You should have at least a preliminary understanding of these classes:
//   <li> <linkto class=Unit>Unit</linkto>
// </prerequisite>
//
// <etymology>
// Based on Unit and the Dimension of a unit in SI defining units
// </etymology>
//
// <synopsis>
// Physical units are strings consisting of one or more names of known
// basic units, separated by '.' or ' ' (for multiplication) or '/' (for
// division). Each name can optionally be preceded by a standard decimal
// prefix, and/or followed by an (optionally signed) exponent.
// Example:
//  km/s/(Mpc.s)2  is identical to km.s-1.Mpc-2.s-2
//
// See the <linkto class=Unit>Unit</linkto> for more details.
//
// The UnitDim class is a private class for use by the Unit classes. It
// contains the dimensions in the 9 basic defining SI units of a unit.
// </synopsis>
//
// <example>
// </example>
//
// <motivation>
// The UnitDim class has been separated to keep the interface between a
// complex unit description string and the basic SI units clean.
// </motivation>
//
// <todo asof="941110">
//   <li> Some inlining (did not work first go)
// </todo>
 
class UnitDim {
  // # Friends
  friend class UnitVal;
  friend class UnitMap;
  // Output the SI dimensions (e.g. 'km/s/g' as 'm kg-1 s-1')
  friend ostream &operator<<(ostream &os, const UnitDim &du);
 
 public:
  // # Enumerations
  //  Enumeration of the order and number of the defining SI units.
  //  If order or contents changed, change also in dimName() and dimFull().
  enum Dim { Dm = 0, Dkg, Ds, DA, DK, Dcd, Dmol, Drad, Dsr, Dnon, Dnumber };
// Constants
// Number of Longs to cater for 9 bytes.
#define UNITDIM_DLNUMBER 3
 
  // Destructor
  ~UnitDim();
 
 protected:
  void init();
  void init(Int pos);
 
 private:
  // # Constructors
  //  Construct a unit with zero dimension in all SI units
  UnitDim() { init(); }
 
  // Copy constructor
  UnitDim(const UnitDim &other);
 
  // Construct a unit dimension with a one in the indicated position (as
  // Dim enumerator) and zeroes in all other units
  UnitDim(Int pos) { init(pos); }
 
  // # Operators
  //  Assignment (copy semantics)
  UnitDim &operator=(const UnitDim &other);
  // Operators to combine unit dimensions
  // <group name="combine">
  // Multiplication adds the unit dimensions of all SI units
  UnitDim &operator*=(const UnitDim &other);
  UnitDim operator*(const UnitDim &other) const;
 
  // Division subtracts the unit dimensions of all SI units
  UnitDim &operator/=(const UnitDim &other);
  UnitDim operator/(const UnitDim &other) const;
  // </group>
  // Compare dimension of units
  // <group name="compare">
  // Compare for equal dimensions
  Bool operator==(const UnitDim &other) const;
  // Compare for unequal dimensions
  Bool operator!=(const UnitDim &other) const;
  // </group>
 
  // # General Member Functions
  //  Raise all SI defining units to an integer power
  UnitDim pow(Int p);
 
  // Get the tag for specified dimension
  static const String &dimName(uInt which);
 
  // Get the full name for the specified dimension
  static const String &dimFull(uInt which);
 
  // # Data Members
  //  1-byte vector to contain the dimensions of the defining SI units
  //  (using same storage as Long vector for speed reasons)
  Long unitLong[UNITDIM_DLNUMBER];
  signed char *unitDim;
};
 
// # Inline Implementations
 
// # Global definitions
//  Output
ostream &operator<<(ostream &os, const UnitDim &du);
 
}  // namespace casacore
 
#endif