diff options
Diffstat (limited to 'base/bind_internal.h.pump')
| -rw-r--r-- | base/bind_internal.h.pump | 148 |
1 files changed, 96 insertions, 52 deletions
diff --git a/base/bind_internal.h.pump b/base/bind_internal.h.pump index 6fd95fe..b1ba2d7 100644 --- a/base/bind_internal.h.pump +++ b/base/bind_internal.h.pump @@ -25,32 +25,103 @@ namespace internal { // The method by which a function is invoked is determined by 3 different // dimensions: // -// 1) The type of function (normal, method, const-method) -// 2) The arity of the function +// 1) The type of function (normal or method). +// 2) The arity of the function. // 3) The number of bound parameters. // -// The FunctionTraitsN classes unwrap the function signature type to -// specialize based on the first two dimensions. The N in FunctionTraitsN -// specifies the 3rd dimension. We could have specified the unbound parameters -// via template parameters, but this method looked cleaner. +// The templates below handle the determination of each of these dimensions. +// In brief: // -// The FunctionTraitsN contains a static DoInvoke() function that is the key to -// implementing type erasure in the Callback() classes. DoInvoke() is a static -// function with a fixed signature that is independent of StorageType; its -// first argument is a pointer to the non-templated common baseclass of -// StorageType. This lets us store pointer to DoInvoke() in a function pointer -// that has knowledge of the specific StorageType, and thus no knowledge of the -// bound function and bound parameter types. +// FunctionTraits<> -- Provides a normalied signature, and other traits. +// InvokerN<> -- Provides a DoInvoke() function that actually executes +// a calback. +// InvokerStorageN<> -- Provides storage for the bound parameters, and +// typedefs to the above. +// +// More details about the design of each class is included in a comment closer +// to their defition. + +// FunctionTraits<> +// +// The FunctionTraits<> template determines the type of function, and also +// creates a NormalizedType used to select the InvokerN classes. It turns out +// that syntactically, you only really have 2 variations when invoking a +// funciton pointer: normal, and method. One is invoked func_ptr(arg1). The +// other is invoked (*obj_->method_ptr(arg1)). +// +// However, in the type system, there are many more distinctions. In standard +// C++, there's all variations of const, and volatile on the function pointer. +// In Windows, there are additional calling conventions (eg., __stdcall, +// __fastcall, etc.). FunctionTraits<> handles categorizing each of these into +// a normalized signature. +// +// Having a NormalizedSignature signature, reduces the combinatoric +// complexity of defintions for the InvokerN<> later. Even though there are +// only 2 syntactic variations on invoking a function, without normalizing the +// signature, there would need to be one specialization of InvokerN for each +// unique (function_type, bound_arg, unbound_args) tuple in order to match all +// function signatures. +// +// By normalizing the function signature, we reduce function_type to exactly 2. + +template <typename Sig> +struct FunctionTraits; + +$range ARITY 0..MAX_ARITY +$for ARITY [[ +$range ARG 1..ARITY + +// Function: Arity $(ARITY). +template <typename R[[]] +$if ARITY > 0[[, ]] $for ARG , [[typename X$(ARG)]]> +struct FunctionTraits<R(*)($for ARG , [[X$(ARG)]])> { + typedef R (*NormalizedSig)($for ARG , [[X$(ARG)]]); + typedef base::false_type IsMethod; +}; + +// Method: Arity $(ARITY). +template <typename R, typename T[[]] +$if ARITY > 0[[, ]] $for ARG , [[typename X$(ARG)]]> +struct FunctionTraits<R(T::*)($for ARG , [[X$(ARG)]])> { + typedef R (T::*NormalizedSig)($for ARG , [[X$(ARG)]]); + typedef base::true_type IsMethod; +}; + +// Const Method: Arity $(ARITY). +template <typename R, typename T[[]] +$if ARITY > 0[[, ]] $for ARG , [[typename X$(ARG)]]> +struct FunctionTraits<R(T::*)($for ARG , [[X$(ARG)]]) const> { + typedef R (T::*NormalizedSig)($for ARG , [[X$(ARG)]]); + typedef base::true_type IsMethod; +}; + +]] $$for ARITY + +// InvokerN<> +// +// The InvokerN templates contain a static DoInvoke() function that is the key +// to implementing type erasure in the Callback() classes. +// +// DoInvoke() is a static function with a fixed signature that is independent +// of StorageType; its first argument is a pointer to the non-templated common +// baseclass of StorageType. This lets us store pointer to DoInvoke() in a +// function pointer that has knowledge of the specific StorageType, and thus +// no knowledge of the bound function and bound parameter types. // // As long as we ensure that DoInvoke() is only used with pointers there were // upcasted from the correct StorageType, we can be sure that execution is // safe. +// +// The InvokerN templates are the only point that knows the number of bound +// and unbound arguments. This is intentional because it allows the other +// templates classes in the system to only have as many specializations as +// the max arity of function we wish to support. $range BOUND 0..MAX_ARITY $for BOUND [[ -template <typename StorageType, typename Sig> -struct FunctionTraits$(BOUND); +template <typename StorageType, typename NormalizedSig> +struct Invoker$(BOUND); $range ARITY 0..MAX_ARITY $for ARITY [[ @@ -74,7 +145,7 @@ $range M_UNBOUND_ARG (M_ARITY - UNBOUND + 1)..M_ARITY template <typename StorageType, typename R[[]] $if ARITY > 0 [[,]][[]] $for ARG , [[typename X$(ARG)]]> -struct FunctionTraits$(BOUND)<StorageType, R(*)($for ARG , [[X$(ARG)]])> { +struct Invoker$(BOUND)<StorageType, R(*)($for ARG , [[X$(ARG)]])> { $if ARITY > 0 [[ COMPILE_ASSERT( @@ -83,8 +154,6 @@ $if ARITY > 0 [[ ]] - typedef base::false_type IsMethod; - static R DoInvoke(InvokerStorageBase* base[[]] $if UNBOUND != 0 [[, ]][[]] $for UNBOUND_ARG , [[const X$(UNBOUND_ARG)& x$(UNBOUND_ARG)]]) { @@ -101,7 +170,7 @@ $if BOUND > 0 [[ // Method: Arity $(M_ARITY) -> $(UNBOUND). template <typename StorageType, typename R, typename T[[]] $if M_ARITY > 0[[, ]] $for M_ARG , [[typename X$(M_ARG)]]> -struct FunctionTraits$(BOUND)<StorageType, R(T::*)($for M_ARG , [[X$(M_ARG)]])> { +struct Invoker$(BOUND)<StorageType, R(T::*)($for M_ARG , [[X$(M_ARG)]])> { $if M_ARITY > 0 [[ COMPILE_ASSERT( @@ -110,8 +179,6 @@ $if M_ARITY > 0 [[ ]] - typedef base::true_type IsMethod; - static R DoInvoke(InvokerStorageBase* base[[]] $if UNBOUND > 0 [[, ]][[]] $for M_UNBOUND_ARG , [[const X$(M_UNBOUND_ARG)& x$(M_UNBOUND_ARG)]]) { @@ -123,31 +190,6 @@ $for M_UNBOUND_ARG , [[x$(M_UNBOUND_ARG)]]); } }; -// Const Method: Arity $(M_ARITY) -> $(UNBOUND). -template <typename StorageType, typename R, typename T[[]] -$if M_ARITY > 0[[, ]] $for M_ARG , [[typename X$(M_ARG)]]> -struct FunctionTraits$(BOUND)<StorageType, R(T::*)($for M_ARG , [[X$(M_ARG)]]) const> { -$if M_ARITY > 0 [[ - - COMPILE_ASSERT( - !($for M_ARG || [[is_non_const_reference<X$(M_ARG)>::value ]]), - do_not_bind_functions_with_nonconst_ref); - -]] - - typedef base::true_type IsMethod; - - static R DoInvoke(InvokerStorageBase* base[[]] -$if UNBOUND > 0 [[, ]] -[[]] $for M_UNBOUND_ARG , [[const X$(M_UNBOUND_ARG)& x$(M_UNBOUND_ARG)]]) { - StorageType* invoker = static_cast<StorageType*>(base); - return (Unwrap(invoker->p1_)->*invoker->f_)([[]] -$for M_BOUND_ARG , [[Unwrap(invoker->p$(M_BOUND_ARG)_)]][[]] -$if UNBOUND > 0 [[$if BOUND > 1 [[, ]]]][[]] -$for M_UNBOUND_ARG , [[x$(M_UNBOUND_ARG)]]); - } -}; - ]] $$ if BOUND ]] $$ if UNBOUND @@ -155,16 +197,18 @@ $for M_UNBOUND_ARG , [[x$(M_UNBOUND_ARG)]]); ]] $$ for BOUND -// These are the actual storage classes for the invokers. +// InvokerStorageN<> +// +// These are the actual storage classes for the Invokers. // // Though these types are "classes", they are being used as structs with // all member variable public. We cannot make it a struct because it inherits // from a class which causes a compiler warning. We cannot add a "Run()" method // that forwards the unbound arguments because that would require we unwrap the -// Sig type like in FunctionTraitsN above to know the return type, and the arity +// Sig type like in InvokerN above to know the return type, and the arity // of Run(). // -// An alternate solution would be to merge FunctionTraitsN and InvokerStorageN, +// An alternate solution would be to merge InvokerN and InvokerStorageN, // but the generated code seemed harder to read. $for BOUND [[ @@ -176,9 +220,9 @@ $for BOUND_ARG , [[typename P$(BOUND_ARG)]]> class InvokerStorage$(BOUND) : public InvokerStorageBase { public: typedef InvokerStorage$(BOUND) StorageType; - typedef FunctionTraits$(BOUND)<StorageType, Sig> FunctionTraits; - typedef typename FunctionTraits::IsMethod IsMethod; - + typedef FunctionTraits<Sig> TargetTraits; + typedef Invoker$(BOUND)<StorageType, typename TargetTraits::NormalizedSig> Invoker; + typedef typename TargetTraits::IsMethod IsMethod; $for BOUND_ARG [[ $if BOUND_ARG == 1 [[ |