MCBase.h

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// # MCBase.h: Base for specific measure conversions
// # Copyright (C) 1995,1996,1997,1998
// # 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 MEASURES_MCBASE_H
#define MEASURES_MCBASE_H
 
// # Includes
#include <casacore/casa/aips.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// # Forward Declarations
class MeasValue;
class MCBase;
class MRBase;
class MConvertBase;
class String;
 
// # Typedefs
 
// <summary>  Base for specific measure conversions </summary>
 
// <use visibility=local>
 
// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="tMeasure" demos="">
// </reviewed>
 
// <prerequisite>
//   <li> <linkto class=Measure>Measure</linkto> class
//   <li> <linkto class=MConvertBase>MConvertBase</linkto>: conversion engine
// </prerequisite>
//
// <etymology>
// Measure, Conversion and Base
// </etymology>
//
// <synopsis>
// MCBase forms the base for the individual state machines doing actual
// conversions between frames. (see e.g. <linkto class=MCEpoch>MCEpoch</linkto>)
//
// It also has a static routine to calculate the state transition table based
// on a list of transitions. The makeState() method find the shortest route
// (weighted if necessary) for a given list of state transitions.
//
// The user of the Measure classes has no direct interaction with this class.
// </synopsis>
//
// <example>
// Convert (with all steps explicit) a UTC to an IAT time.
// <srcblock>
//      #include <casacore/measures/Measures.h>
//      #include <casacore/measures/Measures/MCEpoch.h>
//  cout << "TAI for UTC = MJD(50237.29): " <<
//      MEpoch::Convert(MEpoch(MVEpoch(Quantity(50237.29, "d")),
//                         MEpoch::Ref(MEpoch::UTC)),
//                      MEpoch::Ref(MEpoch::TAI))() <<
//      endl;
// </srcblock>
// To get a static state transition matrix:
// <srcblock>
//  static Bool made = False;       // set not yet done
//  enum types {                // states
//      A=0, B, C, D, E, ntyp };
//  enum routes {               // routes
//      A_B, B_C, B_D, C_D, C_E,
//      D_C, C_B, B_A, D_B, E_C, nrout };
//  static uInt list [nrout][3] = {     // description. The third number
//      {A, B, 0},          // is a penalty hop to weight
//      {B, C, 0},          // against using this route
//      {B, D, 0},
//      {C, D, 0},
//      {C, E, 0},
//      {D, C, 0},
//      {C, B, 0},
//      {B, A, 0},
//      {D, B, 0},
//      {E, C, 0} };
//  static uInt state[ntyp][ntyp];  // the resultant transition matrix
//                  // diagonal == nrout
//  // Make the state machine
//  MCBase::makeState(state[0], ntyp, nrout, routes);
//      made = True;
// </srcblock>
// </example>
//
// <motivation>
//  To have specific conversion bases
// </motivation>
//
// <todo asof="1998/09/21">
//  <li> Nothing I know
// </todo>
 
class MCBase {
 public:
  // # Typedefs
 
  // # Constructors
 
  // # Destructor
  virtual ~MCBase();
 
  // # Operators
 
  // # Enumerations
  //  Each derived class should have a list of routines to be called:
  enum Routes { N_Routes };
 
  // # Member functions
  //  All these functions are called by Measure::Convert classes only
  //  <group>
  //  Create conversion state machine list
  virtual void getConvert(MConvertBase &mc, const MRBase &inref, const MRBase &outref) = 0;
 
  // Create help structures for Measure conversion routines
  virtual void initConvert(uInt which, MConvertBase &mc) = 0;
 
  // Delete the pointers used in the MeasConvert help structure cache
  virtual void clearConvert() = 0;
 
  // Routine to convert a Measure from one reference frame to another
  virtual void doConvert(MeasValue &in, MRBase &inref, MRBase &outref, const MConvertBase &mc) = 0;
  // </group>
 
 protected:
  // The following routines create a state transition matrix from a list
  // of all defined transitions. It uses the following information:
  // <ul>
  //  <li> nrout: the number of transitions; numbered 0, ...
  //  <li> ntyp: the number of states
  //  <li> list: a [nrout][3] list of input and output transition type of
  //        transition and a penalty hop number (<100)
  //  <li> state: a [ntyp][ntyp] transition matrix with diagonal elements set
  //        to nrout.
  // </ul>
  // <group>
  // Routine to make the transition table if necessary
  static void makeState(uInt *state, const uInt ntyp, const uInt nrout, const uInt list[][3]);
  // Return a fromatted String with matrix information (based on < 100 types)
  static String showState(uInt *state, const uInt ntyp, const uInt nrout, const uInt list[][3]);
 
 private:
  // Routine to find the shortest route between two points
  static Bool findState(uInt &len, uInt *state, uInt *mcnt, Bool &okall, Bool *visit,
                        const uInt *tcnt, const uInt *tree, const uInt &in, const uInt &out,
                        const uInt ntyp, const uInt nrout, const uInt list[][3]);
  // </group>
};
 
}  // namespace casacore
 
#endif