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path: root/support/dktools/Dk4Comparable.cpt
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%%	options

copyright owner =       Dirk Krause
copyright year  =       2013-xxxx
license         =       bsd

%%	header

namespace DkTools4 {

  /**	Comparable is a general base class for the library.
  */
  class Comparable
  {
    public:
      /**	Compare object against another object or some data.
	  This comparison is used by sorted containers.
	  Example: When storing persons (name and age) we can use
	  crit=0 as comparison criteria in the container to compare
	  person object against person object. When searching the container
	  for an object with a specific name we can use crit=1 for comparisons
	  of the object against a string.
    	  @param	ptr	Address of other object or data.
	  @param	crit	Comparison criteria, see documentation of
	  derived classes for class-specific numbers.
	  @return	Positive number if larger than ptr, 0 if evaluates
	  equal to ptr, negative number if smaller than ptr.
      */
      virtual
      int
      compareAgainst(void const *ptr, int crit) const = 0;

      /**	Compare two pointers
      		@param	l	Left pointer.
		@param	r	Right pointer.
		@param	cr	Comparison criteria.
		@return	1 for left object is large, 0 for right object
		is large, 0 for objects evaluating equally.
      */
      static
      int
      compareTwoPointers(void const *l, void const *r, int cr);

  };	/* End of class Comparable. */

}	/* End of namespace DkTools4 */


%%	module

#include "Dk4Comparable.h"

int
DkTools4::Comparable::compareTwoPointers(void const *l, void const *r, int cr)
{
  int back = 0;
  if(l) {
    if(r) {
      DkTools4::Comparable const *pl = (DkTools4::Comparable const *)l;
      back = pl->compareAgainst(r, cr);
    } else back = 1;
  } else {
    if(r) back = -1;
  }
  return back;
}