// FastDelegate.h // Efficient delegates in C++ that generate only two lines of asm code! // Documentation is found at http://www.codeproject.com/cpp/FastDelegate.asp // // - Don Clugston, Mar 2004. // Major contributions were made by Jody Hagins. // History: // 24-Apr-04 1.0 * Submitted to CodeProject. // 28-Apr-04 1.1 * Prevent most unsafe uses of evil static function hack. // * Improved syntax for horrible_cast (thanks Paul Bludov). // * Tested on Metrowerks MWCC and Intel ICL (IA32) // * Compiled, but not run, on Comeau C++ and Intel Itanium ICL. // 27-Jun-04 1.2 * Now works on Borland C++ Builder 5.5 // * Now works on /clr "managed C++" code on VC7, VC7.1 // * Comeau C++ now compiles without warnings. // * Prevent the virtual inheritance case from being used on // VC6 and earlier, which generate incorrect code. // * Improved warning and error messages. Non-standard hacks // now have compile-time checks to make them safer. // * implicit_cast used instead of static_cast in many cases. // * If calling a const member function, a const class pointer can be used. // * MakeDelegate() global helper function added to simplify pass-by-value. // * Added fastdelegate.clear() // 16-Jul-04 1.2.1* Workaround for gcc bug (const member function pointers in templates) // 30-Oct-04 1.3 * Support for (non-void) return values. // * No more workarounds in client code! // MSVC and Intel now use a clever hack invented by John Dlugosz: // - The FASTDELEGATEDECLARE workaround is no longer necessary. // - No more warning messages for VC6 // * Less use of macros. Error messages should be more comprehensible. // * Added include guards // * Added FastDelegate::empty() to test if invocation is safe (Thanks Neville Franks). // * Now tested on VS 2005 Express Beta, PGI C++ // 24-Dec-04 1.4 * Added DelegateMemento, to allow collections of disparate delegates. // * <,>,<=,>= comparison operators to allow storage in ordered containers. // * Substantial reduction of code size, especially the 'Closure' class. // * Standardised all the compiler-specific workarounds. // * MFP conversion now works for CodePlay (but not yet supported in the full code). // * Now compiles without warnings on _any_ supported compiler, including BCC 5.5.1 // * New syntax: FastDelegate< int (char *, double) >. // 14-Feb-05 1.4.1* Now treats =0 as equivalent to .clear(), ==0 as equivalent to .empty(). (Thanks elfric). // * Now tested on Intel ICL for AMD64, VS2005 Beta for AMD64 and Itanium. // 30-Mar-05 1.5 * Safebool idiom: "if (dg)" is now equivalent to "if (!dg.empty())" // * Fully supported by CodePlay VectorC // * Bugfix for Metrowerks: empty() was buggy because a valid MFP can be 0 on MWCC! // * More optimal assignment,== and != operators for static function pointers. // // AlliedModders LLC modifications. // // 24-Oct-15 1.6 * Use C++11 variadic templates. // #ifndef FASTDELEGATE_H #define FASTDELEGATE_H #ifdef _MSC_VER # if _MSC_VER > 1000 # pragma once # endif // _MSC_VER > 1000 #endif // #ifdef _MSC_VER #include // to allow <,> comparisons //////////////////////////////////////////////////////////////////////////////// // Configuration options // //////////////////////////////////////////////////////////////////////////////// // Uncomment the following #define for optimally-sized delegates. // In this case, the generated asm code is almost identical to the code you'd get // if the compiler had native support for delegates. // It will not work on systems where sizeof(dataptr) < sizeof(codeptr). // Thus, it will not work for DOS compilers using the medium model. // It will also probably fail on some DSP systems. #define FASTDELEGATE_USESTATICFUNCTIONHACK // Uncomment the next line to allow function declarator syntax. // It is automatically enabled for those compilers where it is known to work. //#define FASTDELEGATE_ALLOW_FUNCTION_TYPE_SYNTAX //////////////////////////////////////////////////////////////////////////////// // Compiler identification for workarounds // //////////////////////////////////////////////////////////////////////////////// // Compiler identification. It's not easy to identify Visual C++ because // many vendors fraudulently define Microsoft's identifiers. #if defined(_MSC_VER) && !defined(__MWERKS__) && !defined(__VECTOR_C) && !defined(__ICL) && !defined(__BORLANDC__) #define FASTDLGT_ISMSVC #if (_MSC_VER <1300) // Many workarounds are required for VC6. #define FASTDLGT_VC6 #pragma warning(disable:4786) // disable this ridiculous warning #endif #endif // Does the compiler uses Microsoft's member function pointer structure? // If so, it needs special treatment. // Metrowerks CodeWarrior, Intel, and CodePlay fraudulently define Microsoft's // identifier, _MSC_VER. We need to filter Metrowerks out. #if defined(_MSC_VER) && !defined(__MWERKS__) #define FASTDLGT_MICROSOFT_MFP #if !defined(__VECTOR_C) // CodePlay doesn't have the __single/multi/virtual_inheritance keywords #define FASTDLGT_HASINHERITANCE_KEYWORDS #endif #endif // Does it allow function declarator syntax? The following compilers are known to work: #if defined(FASTDLGT_ISMSVC) && (_MSC_VER >=1310) // VC 7.1 #define FASTDELEGATE_ALLOW_FUNCTION_TYPE_SYNTAX #endif // Gcc(2.95+), and versions of Digital Mars, Intel and Comeau in common use. #if defined (__DMC__) || defined(__GNUC__) || defined(__ICL) || defined(__COMO__) #define FASTDELEGATE_ALLOW_FUNCTION_TYPE_SYNTAX #endif // It works on Metrowerks MWCC 3.2.2. From boost.Config it should work on earlier ones too. #if defined (__MWERKS__) #define FASTDELEGATE_ALLOW_FUNCTION_TYPE_SYNTAX #endif #ifdef __GNUC__ // Workaround GCC bug #8271 // At present, GCC doesn't recognize constness of MFPs in templates #define FASTDELEGATE_GCC_BUG_8271 #endif //////////////////////////////////////////////////////////////////////////////// // General tricks used in this code // // (a) Error messages are generated by typdefing an array of negative size to // generate compile-time errors. // (b) Warning messages on MSVC are generated by declaring unused variables, and // enabling the "variable XXX is never used" warning. // (c) Unions are used in a few compiler-specific cases to perform illegal casts. // (d) For Microsoft and Intel, when adjusting the 'this' pointer, it's cast to // (char *) first to ensure that the correct number of *bytes* are added. // //////////////////////////////////////////////////////////////////////////////// // Helper templates // //////////////////////////////////////////////////////////////////////////////// namespace fastdelegate { namespace detail { // we'll hide the implementation details in a nested namespace. // implicit_cast< > // I believe this was originally going to be in the C++ standard but // was left out by accident. It's even milder than static_cast. // I use it instead of static_cast<> to emphasize that I'm not doing // anything nasty. // Usage is identical to static_cast<> template inline OutputClass implicit_cast(InputClass input){ return input; } // horrible_cast< > // This is truly evil. It completely subverts C++'s type system, allowing you // to cast from any class to any other class. Technically, using a union // to perform the cast is undefined behaviour (even in C). But we can see if // it is OK by checking that the union is the same size as each of its members. // horrible_cast<> should only be used for compiler-specific workarounds. // Usage is identical to reinterpret_cast<>. // This union is declared outside the horrible_cast because BCC 5.5.1 // can't inline a function with a nested class, and gives a warning. template union horrible_union{ OutputClass out; InputClass in; }; template inline OutputClass horrible_cast(const InputClass input){ horrible_union u; // Cause a compile-time error if in, out and u are not the same size. // If the compile fails here, it means the compiler has peculiar // unions which would prevent the cast from working. static_assert(sizeof(InputClass)==sizeof(u) && sizeof(InputClass)==sizeof(OutputClass), "Can't use horrible cast"); u.in = input; return u.out; } //////////////////////////////////////////////////////////////////////////////// // Workarounds // //////////////////////////////////////////////////////////////////////////////// // Backwards compatibility: This macro used to be necessary in the virtual inheritance // case for Intel and Microsoft. Now it just forward-declares the class. #define FASTDELEGATEDECLARE(CLASSNAME) class CLASSNAME; // Prevent use of the static function hack with the DOS medium model. #ifdef __MEDIUM__ #undef FASTDELEGATE_USESTATICFUNCTIONHACK #endif // DefaultVoid - a workaround for 'void' templates in VC6. // // (1) VC6 and earlier do not allow 'void' as a default template argument. // (2) They also doesn't allow you to return 'void' from a function. // // Workaround for (1): Declare a dummy type 'DefaultVoid' which we use // when we'd like to use 'void'. We convert it into 'void' and back // using the templates DefaultVoidToVoid<> and VoidToDefaultVoid<>. // Workaround for (2): On VC6, the code for calling a void function is // identical to the code for calling a non-void function in which the // return value is never used, provided the return value is returned // in the EAX register, rather than on the stack. // This is true for most fundamental types such as int, enum, void *. // Const void * is the safest option since it doesn't participate // in any automatic conversions. But on a 16-bit compiler it might // cause extra code to be generated, so we disable it for all compilers // except for VC6 (and VC5). #ifdef FASTDLGT_VC6 // VC6 workaround typedef const void * DefaultVoid; #else // On any other compiler, just use a normal void. typedef void DefaultVoid; #endif // Translate from 'DefaultVoid' to 'void'. // Everything else is unchanged template struct DefaultVoidToVoid { typedef T type; }; template <> struct DefaultVoidToVoid { typedef void type; }; // Translate from 'void' into 'DefaultVoid' // Everything else is unchanged template struct VoidToDefaultVoid { typedef T type; }; template <> struct VoidToDefaultVoid { typedef DefaultVoid type; }; //////////////////////////////////////////////////////////////////////////////// // Fast Delegates, part 1: // // Conversion of member function pointer to a standard form // //////////////////////////////////////////////////////////////////////////////// // GenericClass is a fake class, ONLY used to provide a type. // It is vitally important that it is never defined, so that the compiler doesn't // think it can optimize the invocation. For example, Borland generates simpler // code if it knows the class only uses single inheritance. // Compilers using Microsoft's structure need to be treated as a special case. #ifdef FASTDLGT_MICROSOFT_MFP #ifdef FASTDLGT_HASINHERITANCE_KEYWORDS // For Microsoft and Intel, we want to ensure that it's the most efficient type of MFP // (4 bytes), even when the /vmg option is used. Declaring an empty class // would give 16 byte pointers in this case.... class __single_inheritance GenericClass; #endif // ...but for Codeplay, an empty class *always* gives 4 byte pointers. // If compiled with the /clr option ("managed C++"), the JIT compiler thinks // it needs to load GenericClass before it can call any of its functions, // (compiles OK but crashes at runtime!), so we need to declare an // empty class to make it happy. // Codeplay and VC4 can't cope with the unknown_inheritance case either. class GenericClass {}; #else class GenericClass; #endif // The size of a single inheritance member function pointer. const int SINGLE_MEMFUNCPTR_SIZE = sizeof(void (GenericClass::*)()); // SimplifyMemFunc< >::Convert() // // A template function that converts an arbitrary member function pointer into the // simplest possible form of member function pointer, using a supplied 'this' pointer. // According to the standard, this can be done legally with reinterpret_cast<>. // For (non-standard) compilers which use member function pointers which vary in size // depending on the class, we need to use knowledge of the internal structure of a // member function pointer, as used by the compiler. Template specialization is used // to distinguish between the sizes. Because some compilers don't support partial // template specialisation, I use full specialisation of a wrapper struct. // general case -- don't know how to convert it. Force a compile failure template struct SimplifyMemFunc { template inline static GenericClass *Convert(X *pthis, XFuncType function_to_bind, GenericMemFuncType &bound_func) { // Unsupported member function type -- force a compile failure. static_assert(N >= 100, "Unsupported memeber function pointer on this compiler"); return 0; } }; // For compilers where all member func ptrs are the same size, everything goes here. // For non-standard compilers, only single_inheritance classes go here. template <> struct SimplifyMemFunc { template inline static GenericClass *Convert(X *pthis, XFuncType function_to_bind, GenericMemFuncType &bound_func) { #if defined __DMC__ // Digital Mars doesn't allow you to cast between abitrary PMF's, // even though the standard says you can. The 32-bit compiler lets you // static_cast through an int, but the DOS compiler doesn't. bound_func = horrible_cast(function_to_bind); #else bound_func = reinterpret_cast(function_to_bind); #endif return reinterpret_cast(pthis); } }; //////////////////////////////////////////////////////////////////////////////// // Fast Delegates, part 1b: // // Workarounds for Microsoft and Intel // //////////////////////////////////////////////////////////////////////////////// // Compilers with member function pointers which violate the standard (MSVC, Intel, Codeplay), // need to be treated as a special case. #ifdef FASTDLGT_MICROSOFT_MFP // We use unions to perform horrible_casts. I would like to use #pragma pack(push, 1) // at the start of each function for extra safety, but VC6 seems to ICE // intermittently if you do this inside a template. // __multiple_inheritance classes go here // Nasty hack for Microsoft and Intel (IA32 and Itanium) template<> struct SimplifyMemFunc< SINGLE_MEMFUNCPTR_SIZE + sizeof(int) > { template inline static GenericClass *Convert(X *pthis, XFuncType function_to_bind, GenericMemFuncType &bound_func) { // We need to use a horrible_cast to do this conversion. // In MSVC, a multiple inheritance member pointer is internally defined as: union { XFuncType func; struct { GenericMemFuncType funcaddress; // points to the actual member function int delta; // #BYTES to be added to the 'this' pointer }s; } u; // Check that the horrible_cast will work static_assert(sizeof(function_to_bind)==sizeof(u.s), "Can't use horrible cast"); u.func = function_to_bind; bound_func = u.s.funcaddress; return reinterpret_cast(reinterpret_cast(pthis) + u.s.delta); } }; // virtual inheritance is a real nuisance. It's inefficient and complicated. // On MSVC and Intel, there isn't enough information in the pointer itself to // enable conversion to a closure pointer. Earlier versions of this code didn't // work for all cases, and generated a compile-time error instead. // But a very clever hack invented by John M. Dlugosz solves this problem. // My code is somewhat different to his: I have no asm code, and I make no // assumptions about the calling convention that is used. // In VC++ and ICL, a virtual_inheritance member pointer // is internally defined as: struct MicrosoftVirtualMFP { void (GenericClass::*codeptr)(); // points to the actual member function int delta; // #bytes to be added to the 'this' pointer int vtable_index; // or 0 if no virtual inheritance }; // The CRUCIAL feature of Microsoft/Intel MFPs which we exploit is that the // m_codeptr member is *always* called, regardless of the values of the other // members. (This is *not* true for other compilers, eg GCC, which obtain the // function address from the vtable if a virtual function is being called). // Dlugosz's trick is to make the codeptr point to a probe function which // returns the 'this' pointer that was used. // Define a generic class that uses virtual inheritance. // It has a trival member function that returns the value of the 'this' pointer. struct GenericVirtualClass : virtual public GenericClass { typedef GenericVirtualClass * (GenericVirtualClass::*ProbePtrType)(); GenericVirtualClass * GetThis() { return this; } }; // __virtual_inheritance classes go here template <> struct SimplifyMemFunc { template inline static GenericClass *Convert(X *pthis, XFuncType function_to_bind, GenericMemFuncType &bound_func) { union { XFuncType func; GenericClass* (X::*ProbeFunc)(); MicrosoftVirtualMFP s; } u; u.func = function_to_bind; bound_func = reinterpret_cast(u.s.codeptr); union { GenericVirtualClass::ProbePtrType virtfunc; MicrosoftVirtualMFP s; } u2; // Check that the horrible_cast<>s will work static_assert(sizeof(function_to_bind)==sizeof(u.s) && sizeof(function_to_bind)==sizeof(u.ProbeFunc) && sizeof(u2.virtfunc)==sizeof(u2.s), "Can't use horrible cast."); // Unfortunately, taking the address of a MF prevents it from being inlined, so // this next line can't be completely optimised away by the compiler. u2.virtfunc = &GenericVirtualClass::GetThis; u.s.codeptr = u2.s.codeptr; return (pthis->*u.ProbeFunc)(); } }; #if (_MSC_VER <1300) // Nasty hack for Microsoft Visual C++ 6.0 // unknown_inheritance classes go here // There is a compiler bug in MSVC6 which generates incorrect code in this case!! template <> struct SimplifyMemFunc { template inline static GenericClass *Convert(X *pthis, XFuncType function_to_bind, GenericMemFuncType &bound_func) { // There is an apalling but obscure compiler bug in MSVC6 and earlier: // vtable_index and 'vtordisp' are always set to 0 in the // unknown_inheritance case! // This means that an incorrect function could be called!!! // Compiling with the /vmg option leads to potentially incorrect code. // This is probably the reason that the IDE has a user interface for specifying // the /vmg option, but it is disabled - you can only specify /vmg on // the command line. In VC1.5 and earlier, the compiler would ICE if it ever // encountered this situation. // It is OK to use the /vmg option if /vmm or /vms is specified. // Fortunately, the wrong function is only called in very obscure cases. // It only occurs when a derived class overrides a virtual function declared // in a virtual base class, and the member function // points to the *Derived* version of that function. The problem can be // completely averted in 100% of cases by using the *Base class* for the // member fpointer. Ie, if you use the base class as an interface, you'll // stay out of trouble. // Occasionally, you might want to point directly to a derived class function // that isn't an override of a base class. In this case, both vtable_index // and 'vtordisp' are zero, but a virtual_inheritance pointer will be generated. // We can generate correct code in this case. To prevent an incorrect call from // ever being made, on MSVC6 we generate a warning, and call a function to // make the program crash instantly. static_assert(true, "VC6 Compiler Bug"); return 0; } }; #else // Nasty hack for Microsoft and Intel (IA32 and Itanium) // unknown_inheritance classes go here // This is probably the ugliest bit of code I've ever written. Look at the casts! // There is a compiler bug in MSVC6 which prevents it from using this code. template <> struct SimplifyMemFunc { template inline static GenericClass *Convert(X *pthis, XFuncType function_to_bind, GenericMemFuncType &bound_func) { // The member function pointer is 16 bytes long. We can't use a normal cast, but // we can use a union to do the conversion. union { XFuncType func; // In VC++ and ICL, an unknown_inheritance member pointer // is internally defined as: struct { GenericMemFuncType m_funcaddress; // points to the actual member function int delta; // #bytes to be added to the 'this' pointer int vtordisp; // #bytes to add to 'this' to find the vtable int vtable_index; // or 0 if no virtual inheritance } s; } u; // Check that the horrible_cast will work static_assert(sizeof(XFuncType)==sizeof(u.s), "Can't use horrible cast."); u.func = function_to_bind; bound_func = u.s.funcaddress; int virtual_delta = 0; if (u.s.vtable_index) { // Virtual inheritance is used // First, get to the vtable. // It is 'vtordisp' bytes from the start of the class. const int * vtable = *reinterpret_cast( reinterpret_cast(pthis) + u.s.vtordisp ); // 'vtable_index' tells us where in the table we should be looking. virtual_delta = u.s.vtordisp + *reinterpret_cast( reinterpret_cast(vtable) + u.s.vtable_index); } // The int at 'virtual_delta' gives us the amount to add to 'this'. // Finally we can add the three components together. Phew! return reinterpret_cast( reinterpret_cast(pthis) + u.s.delta + virtual_delta); }; }; #endif // MSVC 7 and greater #endif // MS/Intel hacks } // namespace detail //////////////////////////////////////////////////////////////////////////////// // Fast Delegates, part 2: // // Define the delegate storage, and cope with static functions // //////////////////////////////////////////////////////////////////////////////// // DelegateMemento -- an opaque structure which can hold an arbitary delegate. // It knows nothing about the calling convention or number of arguments used by // the function pointed to. // It supplies comparison operators so that it can be stored in STL collections. // It cannot be set to anything other than null, nor invoked directly: // it must be converted to a specific delegate. // Implementation: // There are two possible implementations: the Safe method and the Evil method. // DelegateMemento - Safe version // // This implementation is standard-compliant, but a bit tricky. // A static function pointer is stored inside the class. // Here are the valid values: // +-- Static pointer --+--pThis --+-- pMemFunc-+-- Meaning------+ // | 0 | 0 | 0 | Empty | // | !=0 |(dontcare)| Invoker | Static function| // | 0 | !=0 | !=0* | Method call | // +--------------------+----------+------------+----------------+ // * For Metrowerks, this can be 0. (first virtual function in a // single_inheritance class). // When stored stored inside a specific delegate, the 'dontcare' entries are replaced // with a reference to the delegate itself. This complicates the = and == operators // for the delegate class. // DelegateMemento - 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. In this case the DelegateMemento implementation is simple: // +--pThis --+-- pMemFunc-+-- Meaning---------------------+ // | 0 | 0 | Empty | // | !=0 | !=0* | Static function or method call| // +----------+------------+-------------------------------+ // * For Metrowerks, this can be 0. (first virtual function in a // single_inheritance class). // Note that the Sun C++ and MSVC documentation explicitly state that they // support static_cast between void * and function pointers. 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_pthis(right.m_pthis), m_pFunction(right.m_pFunction) #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(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(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(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(function_to_bind); } inline UnvoidStaticFuncPtr GetStaticFunction() const { return reinterpret_cast(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. static_assert(sizeof(GenericClass *)==sizeof(function_to_bind), "Can't use evil method."); m_pthis = horrible_cast(function_to_bind); // MSVC, SunC++ and DMC accept the following (non-standard) code: // m_pthis = static_cast(static_cast(function_to_bind)); // BCC32, Comeau and DMC accept this method. MSVC7.1 needs __int64 instead of long // m_pthis = reinterpret_cast(reinterpret_cast(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. static_assert(sizeof(UnvoidStaticFuncPtr)==sizeof(this), "Can't use evil method."); return horrible_cast(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(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 // 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(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(&d), &CDerivedClass::SimpleVirtualFunction); // but with the trick you can write // MyDelegate(&d, &CDerivedClass::SimpleVirtualFunction); // RetType is the type the compiler uses in compiling the template. For VC6, // it cannot be void. DesiredRetType is the real type which is returned from // all of the functions. It can be void. // Implicit conversion to "bool" is achieved using the safe_bool idiom, // using member data pointers (MDP). This allows "if (dg)..." syntax // Because some compilers (eg codeplay) don't have a unique value for a zero // MDP, an extra padding member is added to the SafeBool struct. // Some compilers (eg VC6) won't implicitly convert from 0 to an MDP, so // in that case the static function constructor is not made explicit; this // allows "if (dg==0) ..." to compile. template class FastDelegate { private: typedef typename detail::DefaultVoidToVoid::type DesiredRetType; typedef DesiredRetType (*StaticFunctionPtr)(Params... params); typedef RetType (*UnvoidStaticFunctionPtr)(Params... params); typedef RetType (detail::GenericClass::*GenericMemFn)(Params... params); typedef detail::ClosurePtr ClosureType; ClosureType m_Closure; public: // Typedefs to aid generic programming typedef FastDelegate type; // Construction and comparison functions FastDelegate() { clear(); } FastDelegate(const FastDelegate &x) { m_Closure.CopyFrom(this, x.m_Closure); } void operator = (const FastDelegate &x) { m_Closure.CopyFrom(this, x.m_Closure); } bool operator ==(const FastDelegate &x) const { return m_Closure.IsEqual(x.m_Closure); } bool operator !=(const FastDelegate &x) const { return !m_Closure.IsEqual(x.m_Closure); } bool operator <(const FastDelegate &x) const { return m_Closure.IsLess(x.m_Closure); } bool operator >(const FastDelegate &x) const { return x.m_Closure.IsLess(m_Closure); } // Binding to non-const member functions template < class X, class Y > FastDelegate(Y *pthis, DesiredRetType (X::* function_to_bind)(Params... params) ) { m_Closure.bindmemfunc(detail::implicit_cast(pthis), function_to_bind); } template < class X, class Y > inline void bind(Y *pthis, DesiredRetType (X::* function_to_bind)(Params... params)) { m_Closure.bindmemfunc(detail::implicit_cast(pthis), function_to_bind); } // Binding to const member functions. template < class X, class Y > FastDelegate(const Y *pthis, DesiredRetType (X::* function_to_bind)(Params... params) const) { m_Closure.bindconstmemfunc(detail::implicit_cast(pthis), function_to_bind); } template < class X, class Y > inline void bind(const Y *pthis, DesiredRetType (X::* function_to_bind)(Params... params) const) { m_Closure.bindconstmemfunc(detail::implicit_cast(pthis), function_to_bind); } // Static functions. We convert them into a member function call. // This constructor also provides implicit conversion FastDelegate(DesiredRetType (*function_to_bind)(Params... params) ) { bind(function_to_bind); } // for efficiency, prevent creation of a temporary void operator = (DesiredRetType (*function_to_bind)(Params... params) ) { bind(function_to_bind); } inline void bind(DesiredRetType (*function_to_bind)(Params... params)) { m_Closure.bindstaticfunc(this, &FastDelegate::InvokeStaticFunction, function_to_bind); } // Invoke the delegate RetType operator() (Params... params) const { return (m_Closure.GetClosureThis()->*(m_Closure.GetClosureMemPtr()))(params...); } // Implicit conversion to "bool" using the safe_bool idiom private: typedef struct SafeBoolStruct { int a_data_pointer_to_this_is_0_on_buggy_compilers; StaticFunctionPtr m_nonzero; } UselessTypedef; typedef StaticFunctionPtr SafeBoolStruct::*unspecified_bool_type; public: operator unspecified_bool_type() const { return empty() ? 0: &SafeBoolStruct::m_nonzero; } // necessary to allow ==0 to work despite the safe_bool idiom inline bool operator==(StaticFunctionPtr funcptr) { return m_Closure.IsEqualToStaticFuncPtr(funcptr); } inline bool operator!=(StaticFunctionPtr funcptr) { return !m_Closure.IsEqualToStaticFuncPtr(funcptr); } inline bool operator ! () const { // Is it bound to anything? return !m_Closure; } inline bool empty() const { return !m_Closure; } void clear() { m_Closure.clear(); } // Conversion to and from the DelegateMemento storage class const DelegateMemento & GetMemento() { return m_Closure; } void SetMemento(const DelegateMemento &any) { m_Closure.CopyFrom(this, any); } private: // Invoker for static functions RetType InvokeStaticFunction(Params... params) const { return (*(m_Closure.GetStaticFunction()))(params...); } }; //////////////////////////////////////////////////////////////////////////////// // Fast Delegates, part 4: // // FastDelegate<> class (Original author: Jody Hagins) // Allows boost::function style syntax like: // FastDelegate< double (int, long) > // instead of: // FastDelegate2< int, long, double > // //////////////////////////////////////////////////////////////////////////////// #ifdef FASTDELEGATE_ALLOW_FUNCTION_TYPE_SYNTAX //N=0 // Specialization to allow use of // FastDelegate< R ( ) > // instead of // FastDelegate0 < R > template class FastDelegate< R (Params...) > // Inherit from FastDelegate0 so that it can be treated just like a FastDelegate0 : public FastDelegate < R, Params... > { public: // Make using the base type a bit easier via typedef. typedef FastDelegate < R, Params... > BaseType; // Allow users access to the specific type of this delegate. typedef FastDelegate SelfType; // Mimic the base class constructors. FastDelegate() : BaseType() { } template < class X, class Y > FastDelegate(Y * pthis, R (X::* function_to_bind)(Params... params)) : BaseType(pthis, function_to_bind) { } template < class X, class Y > FastDelegate(const Y *pthis, R (X::* function_to_bind)(Params... params) const) : BaseType(pthis, function_to_bind) { } FastDelegate(R (*function_to_bind)(Params... params)) : BaseType(function_to_bind) { } void operator = (const BaseType &x) { *static_cast(this) = x; } }; #endif //FASTDELEGATE_ALLOW_FUNCTION_TYPE_SYNTAX //////////////////////////////////////////////////////////////////////////////// // Fast Delegates, part 5: // // MakeDelegate() helper function // // MakeDelegate(&x, &X::func) returns a fastdelegate of the type // necessary for calling x.func() with the correct number of arguments. // This makes it possible to eliminate many typedefs from user code. // //////////////////////////////////////////////////////////////////////////////// // Also declare overloads of a MakeDelegate() global function to // reduce the need for typedefs. // We need seperate overloads for const and non-const member functions. // Also, because of the weird rule about the class of derived member function pointers, // implicit downcasts may need to be applied later to the 'this' pointer. // That's why two classes (X and Y) appear in the definitions. Y must be implicitly // castable to X. // Workaround for VC6. VC6 needs void return types converted into DefaultVoid. // GCC 3.2 and later won't compile this unless it's preceded by 'typename', // but VC6 doesn't allow 'typename' in this context. // So, I have to use a macro. #ifdef FASTDLGT_VC6 #define FASTDLGT_RETTYPE detail::VoidToDefaultVoid::type #else #define FASTDLGT_RETTYPE RetType #endif //N=1 template FastDelegate MakeDelegate(Y* x, RetType (X::*func)(Params... params)) { return FastDelegate(x, func); } template FastDelegate MakeDelegate(Y* x, RetType (X::*func)(Params... params) const) { return FastDelegate(x, func); } template FastDelegate MakeDelegate(RetType (*func)(Params... params)) { return FastDelegate(func); } // clean up after ourselves... #undef FASTDLGT_RETTYPE } // namespace fastdelegate #endif // !defined(FASTDELEGATE_H)