fastdelegate.h

AMOP 0.3 is an Automatic Mock Object for C++. By using ABI and template techniques, it can simulate

class DelegateMemento {
protected: 
	// the data is protected, not private, because many
	// compilers have problems with template friends.
	typedef void (detail::GenericClass::*GenericMemFuncType)(); // arbitrary MFP.
	detail::GenericClass *m_pthis;
	GenericMemFuncType m_pFunction;

#if !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)
	typedef void (*GenericFuncPtr)(); // arbitrary code pointer
	GenericFuncPtr m_pStaticFunction;
#endif

public:
#if !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)
	DelegateMemento() : m_pthis(0), m_pFunction(0), m_pStaticFunction(0) {};
	void clear() {
		m_pthis=0; m_pFunction=0; m_pStaticFunction=0;
	}
#else
	DelegateMemento() : m_pthis(0), m_pFunction(0) {};
	void clear() {	m_pthis=0; m_pFunction=0;	}
#endif
public:
#if !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)
	inline bool IsEqual (const DelegateMemento &x) const{
	    // We have to cope with the static function pointers as a special case
		if (m_pFunction!=x.m_pFunction) return false;
		// the static function ptrs must either both be equal, or both be 0.
		if (m_pStaticFunction!=x.m_pStaticFunction) return false;
		if (m_pStaticFunction!=0) return m_pthis==x.m_pthis;
		else return true;
	}
#else // Evil Method
	inline bool IsEqual (const DelegateMemento &x) const{
		return m_pthis==x.m_pthis && m_pFunction==x.m_pFunction;
	}
#endif
	// Provide a strict weak ordering for DelegateMementos.
	inline bool IsLess(const DelegateMemento &right) const {
		// deal with static function pointers first
#if !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)
		if (m_pStaticFunction !=0 || right.m_pStaticFunction!=0) 
				return m_pStaticFunction < right.m_pStaticFunction;
#endif
		if (m_pthis !=right.m_pthis) return m_pthis < right.m_pthis;
	// There are no ordering operators for member function pointers, 
	// but we can fake one by comparing each byte. The resulting ordering is
	// arbitrary (and compiler-dependent), but it permits storage in ordered STL containers.
		return memcmp(&m_pFunction, &right.m_pFunction, sizeof(m_pFunction)) < 0;

	}
	// BUGFIX (Mar 2005):
	// We can't just compare m_pFunction because on Metrowerks,
	// m_pFunction can be zero even if the delegate is not empty!
	inline bool operator ! () const		// Is it bound to anything?
	{ return m_pthis==0 && m_pFunction==0; }
	inline bool empty() const		// Is it bound to anything?
	{ return m_pthis==0 && m_pFunction==0; }
public:
	DelegateMemento & operator = (const DelegateMemento &right)  {
		SetMementoFrom(right); 
		return *this;
	}
	inline bool operator <(const DelegateMemento &right) {
		return IsLess(right);
	}
	inline bool operator >(const DelegateMemento &right) {
		return right.IsLess(*this);
	}
	DelegateMemento (const DelegateMemento &right)  : 
		m_pFunction(right.m_pFunction), m_pthis(right.m_pthis)
#if !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)
		, m_pStaticFunction (right.m_pStaticFunction)
#endif
		{}
protected:
	void SetMementoFrom(const DelegateMemento &right)  {
		m_pFunction = right.m_pFunction;
		m_pthis = right.m_pthis;
#if !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)
		m_pStaticFunction = right.m_pStaticFunction;
#endif
	}
};


//						ClosurePtr<>
//
// A private wrapper class that adds function signatures to DelegateMemento.
// It's the class that does most of the actual work.
// The signatures are specified by:
// GenericMemFunc: must be a type of GenericClass member function pointer. 
// StaticFuncPtr:  must be a type of function pointer with the same signature 
//                 as GenericMemFunc.
// UnvoidStaticFuncPtr: is the same as StaticFuncPtr, except on VC6
//                 where it never returns void (returns DefaultVoid instead).

// An outer class, FastDelegateN<>, handles the invoking and creates the
// necessary typedefs.
// This class does everything else.

namespace detail {

template < class GenericMemFunc, class StaticFuncPtr, class UnvoidStaticFuncPtr>
class ClosurePtr : public DelegateMemento {
public:
	// These functions are for setting the delegate to a member function.

	// Here's the clever bit: we convert an arbitrary member function into a 
	// standard form. XMemFunc should be a member function of class X, but I can't 
	// enforce that here. It needs to be enforced by the wrapper class.
	template < class X, class XMemFunc >
	inline void bindmemfunc(X *pthis, XMemFunc function_to_bind ) {
		m_pthis = SimplifyMemFunc< sizeof(function_to_bind) >
			::Convert(pthis, function_to_bind, m_pFunction);
#if !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)
		m_pStaticFunction = 0;
#endif
	}
	// For const member functions, we only need a const class pointer.
	// Since we know that the member function is const, it's safe to 
	// remove the const qualifier from the 'this' pointer with a const_cast.
	// VC6 has problems if we just overload 'bindmemfunc', so we give it a different name.
	template < class X, class XMemFunc>
	inline void bindconstmemfunc(const X *pthis, XMemFunc function_to_bind) {
		m_pthis= SimplifyMemFunc< sizeof(function_to_bind) >
			::Convert(const_cast<X*>(pthis), function_to_bind, m_pFunction);
#if !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)
		m_pStaticFunction = 0;
#endif
	}
#ifdef FASTDELEGATE_GCC_BUG_8271	// At present, GCC doesn't recognize constness of MFPs in templates
	template < class X, class XMemFunc>
	inline void bindmemfunc(const X *pthis, XMemFunc function_to_bind) {
		bindconstmemfunc(pthis, function_to_bind);
#if !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)
		m_pStaticFunction = 0;
#endif
	}
#endif
	// These functions are required for invoking the stored function
	inline GenericClass *GetClosureThis() const { return m_pthis; }
	inline GenericMemFunc GetClosureMemPtr() const { return reinterpret_cast<GenericMemFunc>(m_pFunction); }

// There are a few ways of dealing with static function pointers.
// There's a standard-compliant, but tricky method.
// There's also a straightforward hack, that won't work on DOS compilers using the
// medium memory model. It's so evil that I can't recommend it, but I've
// implemented it anyway because it produces very nice asm code.

#if !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)

//				ClosurePtr<> - Safe version
//
// This implementation is standard-compliant, but a bit tricky.
// I store the function pointer inside the class, and the delegate then
// points to itself. Whenever the delegate is copied, these self-references
// must be transformed, and this complicates the = and == operators.
public:
	// The next two functions are for operator ==, =, and the copy constructor.
	// We may need to convert the m_pthis pointers, so that
	// they remain as self-references.
	template< class DerivedClass >
	inline void CopyFrom (DerivedClass *pParent, const DelegateMemento &x) {
		SetMementoFrom(x);
		if (m_pStaticFunction!=0) {
			// transform self references...
			m_pthis=reinterpret_cast<GenericClass *>(pParent);
		}
	}
	// For static functions, the 'static_function_invoker' class in the parent 
	// will be called. The parent then needs to call GetStaticFunction() to find out 
	// the actual function to invoke.
	template < class DerivedClass, class ParentInvokerSig >
	inline void bindstaticfunc(DerivedClass *pParent, ParentInvokerSig static_function_invoker, 
				StaticFuncPtr function_to_bind ) {
		if (function_to_bind==0) { // cope with assignment to 0
			m_pFunction=0;
		} else { 
			bindmemfunc(pParent, static_function_invoker);
        }
		m_pStaticFunction=reinterpret_cast<GenericFuncPtr>(function_to_bind);
	}
	inline UnvoidStaticFuncPtr GetStaticFunction() const { 
		return reinterpret_cast<UnvoidStaticFuncPtr>(m_pStaticFunction); 
	}
#else

//				ClosurePtr<> - Evil version
//
// For compilers where data pointers are at least as big as code pointers, it is 
// possible to store the function pointer in the this pointer, using another 
// horrible_cast. Invocation isn't any faster, but it saves 4 bytes, and
// speeds up comparison and assignment. If C++ provided direct language support
// for delegates, they would produce asm code that was almost identical to this.
// Note that the Sun C++ and MSVC documentation explicitly state that they 
// support static_cast between void * and function pointers.

	template< class DerivedClass >
	inline void CopyFrom (DerivedClass *pParent, const DelegateMemento &right) {
		SetMementoFrom(right);
	}
	// For static functions, the 'static_function_invoker' class in the parent 
	// will be called. The parent then needs to call GetStaticFunction() to find out 
	// the actual function to invoke.
	// ******** EVIL, EVIL CODE! *******
	template < 	class DerivedClass, class ParentInvokerSig>
	inline void bindstaticfunc(DerivedClass *pParent, ParentInvokerSig static_function_invoker, 
				StaticFuncPtr function_to_bind) {
		if (function_to_bind==0) { // cope with assignment to 0
			m_pFunction=0;
		} else { 
		   // We'll be ignoring the 'this' pointer, but we need to make sure we pass
		   // a valid value to bindmemfunc().
			bindmemfunc(pParent, static_function_invoker);
        }

		// WARNING! Evil hack. We store the function in the 'this' pointer!
		// Ensure that there's a compilation failure if function pointers 
		// and data pointers have different sizes.
		// If you get this error, you need to #undef FASTDELEGATE_USESTATICFUNCTIONHACK.
		typedef int ERROR_CantUseEvilMethod[sizeof(GenericClass *)==sizeof(function_to_bind) ? 1 : -1];
		m_pthis = horrible_cast<GenericClass *>(function_to_bind);
		// MSVC, SunC++ and DMC accept the following (non-standard) code:
//		m_pthis = static_cast<GenericClass *>(static_cast<void *>(function_to_bind));
		// BCC32, Comeau and DMC accept this method. MSVC7.1 needs __int64 instead of long
//		m_pthis = reinterpret_cast<GenericClass *>(reinterpret_cast<long>(function_to_bind));
	}
	// ******** EVIL, EVIL CODE! *******
	// This function will be called with an invalid 'this' pointer!!
	// We're just returning the 'this' pointer, converted into
	// a function pointer!
	inline UnvoidStaticFuncPtr GetStaticFunction() const {
		// Ensure that there's a compilation failure if function pointers 
		// and data pointers have different sizes.
		// If you get this error, you need to #undef FASTDELEGATE_USESTATICFUNCTIONHACK.
		typedef int ERROR_CantUseEvilMethod[sizeof(UnvoidStaticFuncPtr)==sizeof(this) ? 1 : -1];
		return horrible_cast<UnvoidStaticFuncPtr>(this);
	}
#endif // !defined(FASTDELEGATE_USESTATICFUNCTIONHACK)

	// Does the closure contain this static function?
	inline bool IsEqualToStaticFuncPtr(StaticFuncPtr funcptr){
		if (funcptr==0) return empty(); 
	// For the Evil method, if it doesn't actually contain a static function, this will return an arbitrary
	// value that is not equal to any valid function pointer.
		else return funcptr==reinterpret_cast<StaticFuncPtr>(GetStaticFunction());
	}
};


} // namespace detail

////////////////////////////////////////////////////////////////////////////////
//						Fast Delegates, part 3:
//
//				Wrapper classes to ensure type safety
//
////////////////////////////////////////////////////////////////////////////////


// Once we have the member function conversion templates, it's easy to make the
// wrapper classes. So that they will work with as many compilers as possible, 
// the classes are of the form
//   FastDelegate3<int, char *, double>
// They can cope with any combination of parameters. The max number of parameters
// allowed is 8, but it is trivial to increase this limit.
// Note that we need to treat const member functions seperately.
// All this class does is to enforce type safety, and invoke the delegate with
// the correct list of parameters.

// Because of the weird rule about the class of derived member function pointers,
// you sometimes need to apply a downcast to the 'this' pointer.
// This is the reason for the use of "implicit_cast<X*>(pthis)" in the code below. 
// If CDerivedClass is derived from CBaseClass, but doesn't override SimpleVirtualFunction,
// without this trick you'd need to write:
//		MyDelegate(static_cast<CBaseClass *>(&d), &CDerivedClass::SimpleVirtualFunction);
// but with the trick you can write