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simgear/simgear/props/condition.hxx
2014-06-22 15:35:31 +02:00

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2.2 KiB
C++

/**
* \file condition.hxx
* Declarations and inline methods for property conditions.
* Written by David Megginson, started 2000.
* CLO May 2003 - Split out condition specific code.
*
* This file is in the Public Domain, and comes with no warranty.
*/
#ifndef __SG_CONDITION_HXX
#define __SG_CONDITION_HXX
#include <set>
#include <simgear/structure/SGReferenced.hxx>
#include <simgear/structure/SGSharedPtr.hxx>
class SGPropertyNode;
////////////////////////////////////////////////////////////////////////
// Conditions.
////////////////////////////////////////////////////////////////////////
/**
* An encoded condition.
*
* This class encodes a single condition of some sort, possibly
* connected with properties.
*
* This class should migrate to somewhere more general.
*/
class SGCondition : public SGReferenced
{
public:
SGCondition ();
virtual ~SGCondition ();
virtual bool test () const = 0;
virtual void collectDependentProperties(std::set<const SGPropertyNode*>& props) const { }
};
typedef SGSharedPtr<SGCondition> SGConditionRef;
/**
* Base class for a conditional components.
*
* This class manages the conditions and tests; the component should
* invoke the test() method whenever it needs to decide whether to
* active itself, draw itself, and so on.
*/
class SGConditional : public SGReferenced
{
public:
SGConditional ();
virtual ~SGConditional ();
// transfer pointer ownership
virtual void setCondition (SGCondition * condition);
virtual const SGCondition * getCondition () const { return _condition; }
virtual bool test () const;
private:
SGConditionRef _condition;
};
/**
* Global function to make a condition out of properties.
*
* The top-level is always an implicit 'and' group, whatever the
* node's name (it should usually be "condition").
*
* @param node The top-level condition node (usually named "condition").
* @return A pointer to a newly-allocated condition; it is the
* responsibility of the caller to delete the condition when
* it is no longer needed.
*/
SGCondition *sgReadCondition( SGPropertyNode *prop_root,
const SGPropertyNode *node );
#endif // __SG_CONDITION_HXX