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FastDelegate.h
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FastDelegate.h
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// 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.
#ifndef FASTDELEGATE_H
#define FASTDELEGATE_H
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
#include <memory.h> // 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 <class OutputClass, class InputClass>
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 <class OutputClass, class InputClass>
union horrible_union{
OutputClass out;
InputClass in;
};
template <class OutputClass, class InputClass>
inline OutputClass horrible_cast(const InputClass input){
horrible_union<OutputClass, InputClass> 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.
typedef int ERROR_CantUseHorrible_cast[sizeof(InputClass)==sizeof(u)
&& sizeof(InputClass)==sizeof(OutputClass) ? 1 : -1];
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 <class T>
struct DefaultVoidToVoid { typedef T type; };
template <>
struct DefaultVoidToVoid<DefaultVoid> { typedef void type; };
// Translate from 'void' into 'DefaultVoid'
// Everything else is unchanged
template <class T>
struct VoidToDefaultVoid { typedef T type; };
template <>
struct VoidToDefaultVoid<void> { 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 <int N>
struct SimplifyMemFunc {
template <class X, class XFuncType, class GenericMemFuncType>
inline static GenericClass *Convert(X *pthis, XFuncType function_to_bind,
GenericMemFuncType &bound_func) {
// Unsupported member function type -- force a compile failure.
// (it's illegal to have a array with negative size).
typedef char ERROR_Unsupported_member_function_pointer_on_this_compiler[N-100];
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<SINGLE_MEMFUNCPTR_SIZE> {
template <class X, class XFuncType, class GenericMemFuncType>
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<GenericMemFuncType>(function_to_bind);
#else
bound_func = reinterpret_cast<GenericMemFuncType>(function_to_bind);
#endif
return reinterpret_cast<GenericClass *>(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 <class X, class XFuncType, class GenericMemFuncType>
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
typedef int ERROR_CantUsehorrible_cast[sizeof(function_to_bind)==sizeof(u.s)? 1 : -1];
u.func = function_to_bind;
bound_func = u.s.funcaddress;
return reinterpret_cast<GenericClass *>(reinterpret_cast<char *>(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<SINGLE_MEMFUNCPTR_SIZE + 2*sizeof(int) >
{
template <class X, class XFuncType, class GenericMemFuncType>
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<GenericMemFuncType>(u.s.codeptr);
union {
GenericVirtualClass::ProbePtrType virtfunc;
MicrosoftVirtualMFP s;
} u2;
// Check that the horrible_cast<>s will work
typedef int ERROR_CantUsehorrible_cast[sizeof(function_to_bind)==sizeof(u.s)
&& sizeof(function_to_bind)==sizeof(u.ProbeFunc)
&& sizeof(u2.virtfunc)==sizeof(u2.s) ? 1 : -1];
// 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<SINGLE_MEMFUNCPTR_SIZE + 3*sizeof(int) >
{
template <class X, class XFuncType, class GenericMemFuncType>
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.
typedef char ERROR_VC6CompilerBug[-100];
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<SINGLE_MEMFUNCPTR_SIZE + 3*sizeof(int) >
{
template <class X, class XFuncType, class GenericMemFuncType>
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
typedef int ERROR_CantUsehorrible_cast[sizeof(XFuncType)==sizeof(u.s)? 1 : -1];
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<const int *const*>(
reinterpret_cast<const char *>(pthis) + u.s.vtordisp );
// 'vtable_index' tells us where in the table we should be looking.
virtual_delta = u.s.vtordisp + *reinterpret_cast<const int *>(
reinterpret_cast<const char *>(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<GenericClass *>(
reinterpret_cast<char *>(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_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
// 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.
//N=0
template<class RetType=detail::DefaultVoid>
class FastDelegate0 {
private:
typedef typename detail::DefaultVoidToVoid<RetType>::type DesiredRetType;
typedef DesiredRetType (*StaticFunctionPtr)();
typedef RetType (*UnvoidStaticFunctionPtr)();
typedef RetType (detail::GenericClass::*GenericMemFn)();
typedef detail::ClosurePtr<GenericMemFn, StaticFunctionPtr, UnvoidStaticFunctionPtr> ClosureType;
ClosureType m_Closure;
public:
// Typedefs to aid generic programming
typedef FastDelegate0 type;
// Construction and comparison functions
FastDelegate0() { clear(); }
FastDelegate0(const FastDelegate0 &x) {
m_Closure.CopyFrom(this, x.m_Closure); }
void operator = (const FastDelegate0 &x) {
m_Closure.CopyFrom(this, x.m_Closure); }
bool operator ==(const FastDelegate0 &x) const {
return m_Closure.IsEqual(x.m_Closure); }
bool operator !=(const FastDelegate0 &x) const {
return !m_Closure.IsEqual(x.m_Closure); }
bool operator <(const FastDelegate0 &x) const {
return m_Closure.IsLess(x.m_Closure); }
bool operator >(const FastDelegate0 &x) const {
return x.m_Closure.IsLess(m_Closure); }
// Binding to non-const member functions
template < class X, class Y >
FastDelegate0(Y *pthis, DesiredRetType (X::* function_to_bind)() ) {
m_Closure.bindmemfunc(detail::implicit_cast<X*>(pthis), function_to_bind); }
template < class X, class Y >
inline void bind(Y *pthis, DesiredRetType (X::* function_to_bind)()) {
m_Closure.bindmemfunc(detail::implicit_cast<X*>(pthis), function_to_bind); }
// Binding to const member functions.
template < class X, class Y >
FastDelegate0(const Y *pthis, DesiredRetType (X::* function_to_bind)() const) {
m_Closure.bindconstmemfunc(detail::implicit_cast<const X*>(pthis), function_to_bind); }
template < class X, class Y >
inline void bind(const Y *pthis, DesiredRetType (X::* function_to_bind)() const) {
m_Closure.bindconstmemfunc(detail::implicit_cast<const X *>(pthis), function_to_bind); }
// Static functions. We convert them into a member function call.
// This constructor also provides implicit conversion
FastDelegate0(DesiredRetType (*function_to_bind)() ) {
bind(function_to_bind); }
// for efficiency, prevent creation of a temporary
void operator = (DesiredRetType (*function_to_bind)() ) {
bind(function_to_bind); }
inline void bind(DesiredRetType (*function_to_bind)()) {
m_Closure.bindstaticfunc(this, &FastDelegate0::InvokeStaticFunction,
function_to_bind); }
// Invoke the delegate
RetType operator() () const {
return (m_Closure.GetClosureThis()->*(m_Closure.GetClosureMemPtr()))(); }
// 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() const {
return (*(m_Closure.GetStaticFunction()))(); }
};
//N=1
template<class Param1, class RetType=detail::DefaultVoid>
class FastDelegate1 {
private:
typedef typename detail::DefaultVoidToVoid<RetType>::type DesiredRetType;
typedef DesiredRetType (*StaticFunctionPtr)(Param1 p1);
typedef RetType (*UnvoidStaticFunctionPtr)(Param1 p1);
typedef RetType (detail::GenericClass::*GenericMemFn)(Param1 p1);
typedef detail::ClosurePtr<GenericMemFn, StaticFunctionPtr, UnvoidStaticFunctionPtr> ClosureType;
ClosureType m_Closure;
public:
// Typedefs to aid generic programming
typedef FastDelegate1 type;
// Construction and comparison functions
FastDelegate1() { clear(); }
FastDelegate1(const FastDelegate1 &x) {
m_Closure.CopyFrom(this, x.m_Closure); }
void operator = (const FastDelegate1 &x) {
m_Closure.CopyFrom(this, x.m_Closure); }
bool operator ==(const FastDelegate1 &x) const {
return m_Closure.IsEqual(x.m_Closure); }
bool operator !=(const FastDelegate1 &x) const {
return !m_Closure.IsEqual(x.m_Closure); }
bool operator <(const FastDelegate1 &x) const {
return m_Closure.IsLess(x.m_Closure); }
bool operator >(const FastDelegate1 &x) const {
return x.m_Closure.IsLess(m_Closure); }
// Binding to non-const member functions
template < class X, class Y >
FastDelegate1(Y *pthis, DesiredRetType (X::* function_to_bind)(Param1 p1) ) {
m_Closure.bindmemfunc(detail::implicit_cast<X*>(pthis), function_to_bind); }
template < class X, class Y >
inline void bind(Y *pthis, DesiredRetType (X::* function_to_bind)(Param1 p1)) {
m_Closure.bindmemfunc(detail::implicit_cast<X*>(pthis), function_to_bind); }
// Binding to const member functions.
template < class X, class Y >
FastDelegate1(const Y *pthis, DesiredRetType (X::* function_to_bind)(Param1 p1) const) {
m_Closure.bindconstmemfunc(detail::implicit_cast<const X*>(pthis), function_to_bind); }
template < class X, class Y >
inline void bind(const Y *pthis, DesiredRetType (X::* function_to_bind)(Param1 p1) const) {
m_Closure.bindconstmemfunc(detail::implicit_cast<const X *>(pthis), function_to_bind); }
// Static functions. We convert them into a member function call.
// This constructor also provides implicit conversion
FastDelegate1(DesiredRetType (*function_to_bind)(Param1 p1) ) {
bind(function_to_bind); }
// for efficiency, prevent creation of a temporary
void operator = (DesiredRetType (*function_to_bind)(Param1 p1) ) {
bind(function_to_bind); }
inline void bind(DesiredRetType (*function_to_bind)(Param1 p1)) {
m_Closure.bindstaticfunc(this, &FastDelegate1::InvokeStaticFunction,
function_to_bind); }
// Invoke the delegate
RetType operator() (Param1 p1) const {
return (m_Closure.GetClosureThis()->*(m_Closure.GetClosureMemPtr()))(p1); }
// 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 {