FunctionObject.h

/*
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this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
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of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

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and shall be included in all copies or substantial portions of the Software.

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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF TITLE, MERCHANTABILITY,
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WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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All rights reserved.
*/
#ifndef __FUNCTION_OBJECT__
#define __FUNCTION_OBJECT__


#include <Message.h>
#include <Messenger.h>
#include <MessageFilter.h>

#include <Entry.h>
#include <Node.h>


// parameter binders serve to store a copy of a struct and
// pass it in and out by pointers, allowing struct parameters to share
// the same syntax as scalar ones

// You will mostly want to use the NewFunctionObject... convenience
// factories
//

// add more function objects and specialized binders as needed

namespace BPrivate {

template<class P>
class ParameterBinder {
// primitive default binder for scalars
public:
	ParameterBinder() {}
	ParameterBinder(P p)
		:	p(p)
		{}

	P Pass() const
		{ return p; }
private:
	P p;
};


template<>
class ParameterBinder<const BEntry*> {
public:
	ParameterBinder() {}
	ParameterBinder(const BEntry* p)
		:	p(*p)
		{}

	ParameterBinder &operator=(const BEntry* newp)
		{ p = *newp; return *this; }

	const BEntry* Pass() const
		{ return &p; }
private:
	BEntry p;
};


template<>
class ParameterBinder<const entry_ref*> {
public:
	ParameterBinder() {}
	ParameterBinder(const entry_ref* p)
		{
			if (p)
				this->p = *p;
		}

	ParameterBinder &operator=(const entry_ref* newp)
		{ p = *newp; return *this; }

	const entry_ref* Pass() const
		{ return &p; }
private:
	entry_ref p;
};


template<>
class ParameterBinder<const node_ref*> {
public:
	ParameterBinder() {}
	ParameterBinder(const node_ref* p)
		:	p(*p)
		{}

	ParameterBinder &operator=(const node_ref* newp)
		{ p = *newp; return *this; }

	const node_ref* Pass() const
		{ return &p; }
private:
	node_ref p;
};


template<>
class ParameterBinder<const BMessage*> {
public:
	ParameterBinder() {}
	ParameterBinder(const BMessage* p)
		:	p(p ? new BMessage(*p) : NULL)
		{}

	~ParameterBinder()
		{
			delete p;
		}

	ParameterBinder &operator=(const BMessage* newp)
		{
			delete p;
			p = (newp ? new BMessage(*newp) : NULL);
			return *this;
		}

	const BMessage* Pass() const
		{ return p; }

private:
	BMessage* p;
};


class FunctionObject {
public:
	virtual void operator()() = 0;
	virtual ~FunctionObject() {}
};


template<class R>
class FunctionObjectWithResult : public FunctionObject {
public:
	const R &Result() const { return result; }

protected:
	R result;
};


template <class Param1>
class SingleParamFunctionObject : public FunctionObject {
public:
	SingleParamFunctionObject(void (*callThis)(Param1),
		Param1 p1)
		:	function(callThis),
			p1(p1)
		{
		}

	virtual void operator()() { (function)(p1.Pass()); }

private:
	void (*function)(Param1);
	ParameterBinder<Param1> p1;
};


template <class Result, class Param1>
class SingleParamFunctionObjectWithResult : public
	FunctionObjectWithResult<Result> {
public:
	SingleParamFunctionObjectWithResult(Result (*function)(Param1), Param1 p1)
		:	function(function),
			p1(p1)
		{
		}

	virtual void operator()()
		{ FunctionObjectWithResult<Result>::result = (function)(p1.Pass()); }

private:
	Result (*function)(Param1);
	ParameterBinder<Param1> p1;
};


template <class Param1, class Param2>
class TwoParamFunctionObject : public FunctionObject {
public:
	TwoParamFunctionObject(void (*callThis)(Param1, Param2),
		Param1 p1, Param2 p2)
		:	function(callThis),
			p1(p1),
			p2(p2)
		{
		}

	virtual void operator()() { (function)(p1.Pass(), p2.Pass()); }

private:
	void (*function)(Param1, Param2);
	ParameterBinder<Param1> p1;
	ParameterBinder<Param2> p2;
};


template <class Param1, class Param2, class Param3>
class ThreeParamFunctionObject : public FunctionObject {
public:
	ThreeParamFunctionObject(void (*callThis)(Param1, Param2, Param3),
		Param1 p1, Param2 p2, Param3 p3)
		:	function(callThis),
			p1(p1),
			p2(p2),
			p3(p3)
		{
		}

	virtual void operator()() { (function)(p1.Pass(), p2.Pass(), p3.Pass()); }

private:
	void (*function)(Param1, Param2, Param3);
	ParameterBinder<Param1> p1;
	ParameterBinder<Param2> p2;
	ParameterBinder<Param3> p3;
};


template <class Result, class Param1, class Param2, class Param3>
class ThreeParamFunctionObjectWithResult : public
	FunctionObjectWithResult<Result> {
public:
	ThreeParamFunctionObjectWithResult(
		Result (*callThis)(Param1, Param2, Param3),
		Param1 p1, Param2 p2, Param3 p3)
		:	function(callThis),
			p1(p1),
			p2(p2),
			p3(p3)
		{
		}

	virtual void operator()()
		{ FunctionObjectWithResult<Result>::result
			= (function)(p1.Pass(), p2.Pass(), p3.Pass()); }

private:
	Result (*function)(Param1, Param2, Param3);
	ParameterBinder<Param1> p1;
	ParameterBinder<Param2> p2;
	ParameterBinder<Param3> p3;
};


template <class Param1, class Param2, class Param3, class Param4>
class FourParamFunctionObject : public FunctionObject {
public:
	FourParamFunctionObject(void (*callThis)(Param1, Param2, Param3, Param4),
		Param1 p1, Param2 p2, Param3 p3, Param4 p4)
		:	function(callThis),
			p1(p1),
			p2(p2),
			p3(p3),
			p4(p4)
		{
		}

	virtual void operator()()
		{ (function)(p1.Pass(), p2.Pass(), p3.Pass(), p4.Pass()); }

private:
	void (*function)(Param1, Param2, Param3, Param4);
	ParameterBinder<Param1> p1;
	ParameterBinder<Param2> p2;
	ParameterBinder<Param3> p3;
	ParameterBinder<Param4> p4;
};


template <class Result, class Param1, class Param2, class Param3,
	class Param4>
class FourParamFunctionObjectWithResult : public
	FunctionObjectWithResult<Result>  {
public:
	FourParamFunctionObjectWithResult(
		Result (*callThis)(Param1, Param2, Param3, Param4),
		Param1 p1, Param2 p2, Param3 p3, Param4 p4)
		:	function(callThis),
			p1(p1),
			p2(p2),
			p3(p3),
			p4(p4)
		{
		}

	virtual void operator()()
		{ FunctionObjectWithResult<Result>::result
			= (function)(p1.Pass(), p2.Pass(), p3.Pass(), p4.Pass()); }

private:
	Result (*function)(Param1, Param2, Param3, Param4);
	ParameterBinder<Param1> p1;
	ParameterBinder<Param2> p2;
	ParameterBinder<Param3> p3;
	ParameterBinder<Param4> p4;
};


template<class T>
class PlainMemberFunctionObject : public FunctionObject {
public:
	PlainMemberFunctionObject(void (T::*function)(), T* onThis)
		:	function(function),
			target(onThis)
		{
		}

	virtual void operator()()
		{ (target->*function)(); }

private:
	void (T::*function)();
	T* target;
};


template<class T>
class PlainLockingMemberFunctionObject : public FunctionObject {
public:
	PlainLockingMemberFunctionObject(void (T::*function)(), T* target)
		:	function(function),
			messenger(target)
		{
		}

	virtual void operator()()
		{
			T* target = dynamic_cast<T*>(messenger.Target(NULL));
			if (!target || !messenger.LockTarget())
				return;
			(target->*function)();
			target->Looper()->Unlock();
		}

private:
	void (T::*function)();
	BMessenger messenger;
};


template<class T, class R>
class PlainMemberFunctionObjectWithResult : public
	FunctionObjectWithResult<R> {
public:
	PlainMemberFunctionObjectWithResult(R (T::*function)(), T* onThis)
		:	function(function),
			target(onThis)
		{
		}

	virtual void operator()()
		{ FunctionObjectWithResult<R>::result = (target->*function)(); }


private:
	R (T::*function)();
	T* target;
};


template<class T, class Param1>
class SingleParamMemberFunctionObject : public FunctionObject {
public:
	SingleParamMemberFunctionObject(void (T::*function)(Param1),
		T* onThis, Param1 p1)
		:	function(function),
			target(onThis),
			p1(p1)
		{
		}

	virtual void operator()()
		{ (target->*function)(p1.Pass()); }

private:
	void (T::*function)(Param1);
	T* target;
	ParameterBinder<Param1> p1;
};


template<class T, class Param1, class Param2>
class TwoParamMemberFunctionObject : public FunctionObject {
public:
	TwoParamMemberFunctionObject(void (T::*function)(Param1, Param2),
		T* onThis, Param1 p1, Param2 p2)
		:	function(function),
			target(onThis),
			p1(p1),
			p2(p2)
		{
		}

	virtual void operator()()
		{ (target->*function)(p1.Pass(), p2.Pass()); }


protected:
	void (T::*function)(Param1, Param2);
	T* target;
	ParameterBinder<Param1> p1;
	ParameterBinder<Param2> p2;
};


template<class T, class R, class Param1>
class SingleParamMemberFunctionObjectWithResult : public
	FunctionObjectWithResult<R> {
public:
	SingleParamMemberFunctionObjectWithResult(R (T::*function)(Param1),
		T* onThis, Param1 p1)
		:	function(function),
			target(onThis),
			p1(p1)
		{
		}

	virtual void operator()()
		{ FunctionObjectWithResult<R>::result
			= (target->*function)(p1.Pass()); }

protected:
	R (T::*function)(Param1);
	T* target;
	ParameterBinder<Param1> p1;
};


template<class T, class R, class Param1, class Param2>
class TwoParamMemberFunctionObjectWithResult : public
	FunctionObjectWithResult<R> {
public:
	TwoParamMemberFunctionObjectWithResult(R (T::*function)(Param1, Param2),
		T* onThis, Param1 p1, Param2 p2)
		:	function(function),
			target(onThis),
			p1(p1),
			p2(p2)
		{
		}

	virtual void operator()()
		{ FunctionObjectWithResult<R>::result
			= (target->*function)(p1.Pass(), p2.Pass()); }

protected:
	R (T::*function)(Param1, Param2);
	T* target;
	ParameterBinder<Param1> p1;
	ParameterBinder<Param2> p2;
};


// convenience factory functions
// NewFunctionObject
// NewMemberFunctionObject
// NewMemberFunctionObjectWithResult
// NewLockingMemberFunctionObject
//
// ... add the missing ones as needed

template<class Param1>
SingleParamFunctionObject<Param1>*
NewFunctionObject(void (*function)(Param1), Param1 p1)
{
	return new SingleParamFunctionObject<Param1>(function, p1);
}


template<class Param1, class Param2>
TwoParamFunctionObject<Param1, Param2>*
NewFunctionObject(void (*function)(Param1, Param2), Param1 p1, Param2 p2)
{
	return new TwoParamFunctionObject<Param1, Param2>(function, p1, p2);
}


template<class Param1, class Param2, class Param3>
ThreeParamFunctionObject<Param1, Param2, Param3>*
NewFunctionObject(void (*function)(Param1, Param2, Param3),
	Param1 p1, Param2 p2, Param3 p3)
{
	return new ThreeParamFunctionObject<Param1, Param2, Param3>
		(function, p1, p2, p3);
}


template<class T>
PlainMemberFunctionObject<T>*
NewMemberFunctionObject(void (T::*function)(), T* onThis)
{
	return new PlainMemberFunctionObject<T>(function, onThis);
}


template<class T, class Param1>
SingleParamMemberFunctionObject<T, Param1>*
NewMemberFunctionObject(void (T::*function)(Param1), T* onThis, Param1 p1)
{
	return new SingleParamMemberFunctionObject<T, Param1>
		(function, onThis, p1);
}


template<class T, class Param1, class Param2>
TwoParamMemberFunctionObject<T, Param1, Param2>*
NewMemberFunctionObject(void (T::*function)(Param1, Param2), T* onThis,
		Param1 p1, Param2 p2)
{
	return new TwoParamMemberFunctionObject<T, Param1, Param2>
		(function, onThis, p1, p2);
}


template<class T, class R, class Param1, class Param2>
TwoParamMemberFunctionObjectWithResult<T, R, Param1, Param2>*
NewMemberFunctionObjectWithResult(R (T::*function)(Param1, Param2),
	T* onThis, Param1 p1, Param2 p2)
{
	return new TwoParamMemberFunctionObjectWithResult<T, R, Param1, Param2>
		(function, onThis, p1, p2);
}


template<class HandlerOrSubclass>
PlainLockingMemberFunctionObject<HandlerOrSubclass>*
NewLockingMemberFunctionObject(void (HandlerOrSubclass::*function)(),
	HandlerOrSubclass* onThis)
{
	return new PlainLockingMemberFunctionObject<HandlerOrSubclass>
		(function, onThis);
}

} // namespace BPrivate

using namespace BPrivate;

#endif	// __FUNCTION_OBJECT__