467 lines
16 KiB
C
467 lines
16 KiB
C
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////////////////////////////////////////////////////////////////////////////////
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// The Loki Library
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// Copyright (c) 2001 by Andrei Alexandrescu
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// This code accompanies the book:
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// Alexandrescu, Andrei. "Modern C++ Design: Generic Programming and Design
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// Patterns Applied". Copyright (c) 2001. Addison-Wesley.
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// Permission to use, copy, modify, distribute and sell this software for any
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// purpose is hereby granted without fee, provided that the above copyright
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// notice appear in all copies and that both that copyright notice and this
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// permission notice appear in supporting documentation.
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// The author or Addison-Welsey Longman make no representations about the
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// suitability of this software for any purpose. It is provided "as is"
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// without express or implied warranty.
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////////////////////////////////////////////////////////////////////////////////
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// Last update: Oct 28, 2002
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// Because MSVC 6.0 does not allow a functions with a return
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// type of cv void to return an expression of type "cv void" (6.6.3), this
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// port currently *does not* support void as return type.
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//
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// Because the VC 6.0 does not support explicit template argument specification
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// for member functions (14.8.1), I added dummy parameters to functions
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// requiring this feature.
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// For example:
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// The original declaration of BasicDispatcher::Add looks like this:
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//
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// template <class SomeLhs, class SomeRhs>
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// void Add(CallbackType fun);
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// and you call it like this:
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// obj.Add<Type1, Type2>(yourFun);
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//
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// This port uses:
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//
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// template <class SomeLhs, class SomeRhs>
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// void Add(CallbackType fun, SomeLhs* pDummy1, SomeRhs* pDummy2);
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//
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// and you call it like this:
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// obj.Add(yourFun, (Type1*)0, (Type2*)0);
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#ifndef MULTIMETHODS_INC_
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#define MULTIMETHODS_INC_
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#include "Typelist.h"
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#include "TypeInfo.h"
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#include "Functor.h"
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#include "AssocVector.h"
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////////////////////////////////////////////////////////////////////////////////
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// IMPORTANT NOTE:
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// The double dispatchers implemented below differ from the excerpts shown in
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// the book - they are simpler while respecting the same interface.
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////////////////////////////////////////////////////////////////////////////////
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namespace Loki
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{
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////////////////////////////////////////////////////////////////////////////////
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// class template InvocationTraits (helper)
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// Helps implementing optional symmetry
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////////////////////////////////////////////////////////////////////////////////
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namespace Private
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{
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template <class SomeLhs, class SomeRhs,
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class Executor, typename ResultType>
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struct InvocationTraits
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{
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static ResultType
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DoDispatch(SomeLhs& lhs, SomeRhs& rhs, Executor& exec, Int2Type<false>)
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{
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return exec.Fire(lhs, rhs);
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}
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static ResultType DoDispatch( SomeLhs& lhs, SomeRhs& rhs,
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Executor& exec, Int2Type<true>)
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{
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return exec.Fire(rhs, lhs);
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}
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};
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}
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////////////////////////////////////////////////////////////////////////////////
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// class template StaticDispatcher
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// Implements an automatic static double dispatcher based on two typelists
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////////////////////////////////////////////////////////////////////////////////
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template
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<
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class Executor,
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class BaseLhs,
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class TypesLhs,
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bool symmetric = true,
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class BaseRhs = BaseLhs,
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class TypesRhs = TypesLhs,
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typename ResultType = int/*void*/
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>
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class StaticDispatcher
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{
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template <class SomeLhs>
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static ResultType DispatchRhs( SomeLhs& lhs, BaseRhs& rhs,
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Executor exec, NullType)
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{ return exec.OnError(lhs, rhs); }
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template <class Head, class Tail, class SomeLhs>
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static ResultType DispatchRhs(SomeLhs& lhs, BaseRhs& rhs,
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Executor exec, Typelist<Head, Tail>)
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{
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if (Head* p2 = dynamic_cast<Head*>(&rhs))
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{
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Int2Type<(symmetric &&
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int(TL::IndexOf<TypesRhs, Head>::value) <
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int(TL::IndexOf<TypesLhs, SomeLhs>::value))> i2t;
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typedef Private::InvocationTraits<
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SomeLhs, Head, Executor, ResultType> CallTraits;
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return CallTraits::DoDispatch(lhs, *p2, exec, i2t);
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}
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return DispatchRhs(lhs, rhs, exec, Tail());
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}
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static ResultType DispatchLhs( BaseLhs& lhs, BaseRhs& rhs,
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Executor exec, NullType)
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{ return exec.OnError(lhs, rhs); }
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template <class Head, class Tail>
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static ResultType DispatchLhs( BaseLhs& lhs, BaseRhs& rhs,
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Executor exec, Typelist<Head, Tail>)
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{
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if (Head* p1 = dynamic_cast<Head*>(&lhs))
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{
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return DispatchRhs(*p1, rhs, exec, TypesRhs());
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}
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return DispatchLhs(lhs, rhs, exec, Tail());
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}
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public:
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static ResultType Go( BaseLhs& lhs, BaseRhs& rhs,
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Executor exec)
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{ return DispatchLhs(lhs, rhs, exec, TypesLhs()); }
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};
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////////////////////////////////////////////////////////////////////////////////
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// class template BasicDispatcher
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// Implements a logarithmic double dispatcher for functors (or functions)
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// Doesn't offer automated casts or symmetry
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////////////////////////////////////////////////////////////////////////////////
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template
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<
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class BaseLhs,
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class BaseRhs = BaseLhs,
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typename ResultType = int/*void*/,
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typename CallbackType = ResultType (*)(BaseLhs&, BaseRhs&)
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>
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class BasicDispatcher
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{
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typedef std::pair<TypeInfo,TypeInfo> KeyType;
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typedef CallbackType MappedType;
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typedef AssocVector<KeyType, MappedType> MapType;
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MapType callbackMap_;
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void DoAdd(TypeInfo lhs, TypeInfo rhs, CallbackType fun);
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bool DoRemove(TypeInfo lhs, TypeInfo rhs);
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public:
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template <class SomeLhs, class SomeRhs>
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void Add(CallbackType fun, SomeLhs* pDummy1, SomeRhs* pDummy2)
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{
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DoAdd(typeid(SomeLhs), typeid(SomeRhs), fun);
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}
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template <class SomeLhs, class SomeRhs>
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bool Remove(SomeLhs pDummy1, SomeRhs pDummy2)
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{
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return DoRemove(typeid(SomeLhs), typeid(SomeRhs));
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}
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ResultType Go(BaseLhs& lhs, BaseRhs& rhs);
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};
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// Non-inline to reduce compile time overhead...
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template <class BaseLhs, class BaseRhs,
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typename ResultType, typename CallbackType>
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void BasicDispatcher<BaseLhs,BaseRhs,ResultType,CallbackType>
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::DoAdd(TypeInfo lhs, TypeInfo rhs, CallbackType fun)
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{
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callbackMap_[KeyType(lhs, rhs)] = fun;
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}
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template <class BaseLhs, class BaseRhs,
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typename ResultType, typename CallbackType>
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bool BasicDispatcher<BaseLhs,BaseRhs,ResultType,CallbackType>
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::DoRemove(TypeInfo lhs, TypeInfo rhs)
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{
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return callbackMap_.erase(KeyType(lhs, rhs)) == 1;
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}
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template <class BaseLhs, class BaseRhs,
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typename ResultType, typename CallbackType>
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ResultType BasicDispatcher<BaseLhs,BaseRhs,ResultType,CallbackType>
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::Go(BaseLhs& lhs, BaseRhs& rhs)
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{
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typename MapType::key_type k(typeid(lhs),typeid(rhs));
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typename MapType::iterator i = callbackMap_.find(k);
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if (i == callbackMap_.end())
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{
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throw std::runtime_error("Function not found");
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}
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return (i->second)(lhs, rhs);
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}
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struct BasicDispatcherWrapper
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{
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template <class T, class U, class V, class W>
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struct In
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{
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typedef BasicDispatcher<T, U, V, W> type;
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};
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};
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////////////////////////////////////////////////////////////////////////////////
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// class template StaticCaster
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// Implementation of the CastingPolicy used by FunctorDispatcher
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////////////////////////////////////////////////////////////////////////////////
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template <class To, class From>
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struct StaticCaster
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{
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static To& Cast(From& obj)
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{
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return static_cast<To&>(obj);
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}
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};
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struct StaticCasterWrapper
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{
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template <class T, class U>
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struct In
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{
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typedef StaticCaster<T, U> type;
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};
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};
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////////////////////////////////////////////////////////////////////////////////
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// class template DynamicCaster
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// Implementation of the CastingPolicy used by FunctorDispatcher
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////////////////////////////////////////////////////////////////////////////////
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template <class To, class From>
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struct DynamicCaster
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{
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static To& Cast(From& obj)
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{
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return dynamic_cast<To&>(obj);
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}
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};
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struct DynamicCasterWrapper
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{
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template <class T, class U>
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struct In
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{
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typedef DynamicCaster<T, U> type;
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};
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};
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////////////////////////////////////////////////////////////////////////////////
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// class template Private::FnDispatcherHelper
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// Implements trampolines and argument swapping used by FnDispatcher
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////////////////////////////////////////////////////////////////////////////////
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namespace Private
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{
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template
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<
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class BaseLhs, class BaseRhs, class SomeLhs, class SomeRhs,
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typename ResultType, class CastLhs, class CastRhs,
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ResultType (*Callback)(SomeLhs&, SomeRhs&)
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>
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struct FnDispatcherHelper
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{
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static ResultType Trampoline(BaseLhs& lhs, BaseRhs& rhs)
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{
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return Callback(CastLhs::Cast(lhs), CastRhs::Cast(rhs));
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}
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static ResultType TrampolineR(BaseRhs& rhs, BaseLhs& lhs)
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{
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return Trampoline(lhs, rhs);
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}
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};
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}
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////////////////////////////////////////////////////////////////////////////////
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// class template FnDispatcher
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// Implements an automatic logarithmic double dispatcher for functions
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// Features automated conversions
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////////////////////////////////////////////////////////////////////////////////
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template <class BaseLhs, class BaseRhs = BaseLhs,
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typename ResultType = int/*void*/,
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class CastingPolicy = DynamicCasterWrapper,
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class DispatcherBackend = BasicDispatcherWrapper>
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class FnDispatcher
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{
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ApplyInnerType4<DispatcherBackend, BaseLhs, BaseRhs, ResultType,
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ResultType (*)(BaseLhs&, BaseRhs&)>::type backEnd_;
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public:
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template <class SomeLhs, class SomeRhs>
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void Add(ResultType (*pFun)(BaseLhs&, BaseRhs&), SomeLhs* pDummy1, SomeRhs* pDummy2)
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{
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return backEnd_.Add(pFun, pDummy1, pDummy2);
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}
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template <class SomeLhs, class SomeRhs,
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ResultType (*callback)(SomeLhs&, SomeRhs&)>
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void Add(SomeLhs* pDummy1, SomeRhs* pDummy2)
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{
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typedef Private::FnDispatcherHelper<
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BaseLhs, BaseRhs,
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SomeLhs, SomeRhs,
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ResultType,
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typename ApplyInnerType2<CastingPolicy, SomeLhs,BaseLhs>::type,
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typename ApplyInnerType2<CastingPolicy,SomeRhs,BaseRhs>::type,
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callback> Local;
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Add(&Local::Trampoline, (SomeLhs*)0, (SomeRhs*)0);
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}
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template <class SomeLhs, class SomeRhs,
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ResultType (*callback)(SomeLhs&, SomeRhs&)>
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void Add(SomeLhs* pDummy1, SomeRhs* pDummy2, bool Symmetric)
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{
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typedef Private::FnDispatcherHelper<
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BaseLhs, BaseRhs,
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SomeLhs, SomeRhs,
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ResultType,
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typename ApplyInnerType2<CastingPolicy, SomeLhs,BaseLhs>::type,
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typename ApplyInnerType2<CastingPolicy,SomeRhs,BaseRhs>::type,
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callback> Local;
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Add(&Local::Trampoline, (SomeLhs*)0, (SomeRhs*)0);
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if (Symmetric)
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{
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Add(&Local::Trampoline, (SomeLhs*)0, (SomeRhs*)0);
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}
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}
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template <class SomeLhs, class SomeRhs>
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void Remove(SomeLhs* pDummy1, SomeRhs* pDummy2)
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{
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backEnd_.Remove(pDummy1, pDummy2);
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}
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ResultType Go(BaseLhs& lhs, BaseRhs& rhs)
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{
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return backEnd_.Go(lhs, rhs);
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}
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};
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////////////////////////////////////////////////////////////////////////////////
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// class template FunctorDispatcherAdaptor
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// permits use of FunctorDispatcher under gcc.2.95.2/3
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///////////////////////////////////////////////////////////////////////////////
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namespace Private
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{
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template <class BaseLhs, class BaseRhs,
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class SomeLhs, class SomeRhs,
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typename ResultType,
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class CastLhs, class CastRhs,
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class Fun, bool SwapArgs>
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class FunctorDispatcherHelper
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{
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Fun fun_;
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ResultType Fire(BaseLhs& lhs, BaseRhs& rhs,Int2Type<false>)
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{
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return fun_(CastLhs::Cast(lhs), CastRhs::Cast(rhs));
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}
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ResultType Fire(BaseLhs& rhs, BaseRhs& lhs,Int2Type<true>)
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{
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return fun_(CastLhs::Cast(lhs), CastRhs::Cast(rhs));
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}
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public:
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FunctorDispatcherHelper(const Fun& fun) : fun_(fun) {}
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ResultType operator()(BaseLhs& lhs, BaseRhs& rhs)
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{
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return Fire(lhs,rhs,Int2Type<SwapArgs>());
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|
|
}
|
||
|
|
};
|
||
|
|
}
|
||
|
|
|
||
|
|
////////////////////////////////////////////////////////////////////////////////
|
||
|
|
// class template FunctorDispatcher
|
||
|
|
// Implements a logarithmic double dispatcher for functors
|
||
|
|
// Features automated casting
|
||
|
|
////////////////////////////////////////////////////////////////////////////////
|
||
|
|
|
||
|
|
template <class BaseLhs, class BaseRhs = BaseLhs,
|
||
|
|
typename ResultType = int/*void*/,
|
||
|
|
class CastingPolicy = DynamicCasterWrapper,
|
||
|
|
class DispatcherBackend = BasicDispatcherWrapper>
|
||
|
|
class FunctorDispatcher
|
||
|
|
{
|
||
|
|
typedef TYPELIST_2(BaseLhs&, BaseRhs&) ArgsList;
|
||
|
|
typedef Functor<ResultType, ArgsList, DEFAULT_THREADING> FunctorType;
|
||
|
|
|
||
|
|
ApplyInnerType4<DispatcherBackend,BaseLhs, BaseRhs, ResultType, FunctorType>::type backEnd_;
|
||
|
|
|
||
|
|
public:
|
||
|
|
template <class SomeLhs, class SomeRhs, class Fun>
|
||
|
|
void Add(const Fun& fun, SomeLhs* pDummy1, SomeRhs* pDummy2)
|
||
|
|
{
|
||
|
|
typedef typename ApplyInnerType2<CastingPolicy,SomeLhs, BaseLhs>::type CastOne;
|
||
|
|
typedef typename ApplyInnerType2<CastingPolicy,SomeRhs, BaseRhs>::type CastTwo;
|
||
|
|
typedef Private::FunctorDispatcherHelper<
|
||
|
|
BaseLhs, BaseRhs,
|
||
|
|
SomeLhs, SomeRhs,
|
||
|
|
ResultType,
|
||
|
|
CastOne,
|
||
|
|
CastTwo,
|
||
|
|
Fun, false> Adapter;
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
backEnd_.Add(FunctorType(Adapter(fun), (int*) 0), pDummy1, pDummy2);
|
||
|
|
}
|
||
|
|
template <class SomeLhs, class SomeRhs, class Fun>
|
||
|
|
void Add(const Fun& fun, SomeLhs* pDummy1, SomeRhs* pDummy2, bool symmetric)
|
||
|
|
{
|
||
|
|
Add(fun, pDummy1, pDummy2);
|
||
|
|
|
||
|
|
if (symmetric)
|
||
|
|
{
|
||
|
|
// Note: symmetry only makes sense where BaseLhs==BaseRhs
|
||
|
|
typedef Private::FunctorDispatcherHelper<
|
||
|
|
BaseLhs, BaseLhs,
|
||
|
|
SomeLhs, SomeRhs,
|
||
|
|
ResultType,
|
||
|
|
ApplyInnerType2<CastingPolicy,SomeLhs, BaseLhs>::type,
|
||
|
|
ApplyInnerType2<CastingPolicy,SomeRhs, BaseLhs>::type,
|
||
|
|
Fun, true> AdapterR;
|
||
|
|
|
||
|
|
backEnd_.Add(FunctorType(Adapter(fun)), pDummy1, pDummy2);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
template <class SomeLhs, class SomeRhs>
|
||
|
|
void Remove(SomeLhs* pDummy1, SomeRhs* pDummy2)
|
||
|
|
{
|
||
|
|
backEnd_.Remove(pDummy1, pDummy2);
|
||
|
|
}
|
||
|
|
|
||
|
|
ResultType Go(BaseLhs& lhs, BaseRhs& rhs)
|
||
|
|
{
|
||
|
|
return backEnd_.Go(lhs, rhs);
|
||
|
|
}
|
||
|
|
};
|
||
|
|
} // namespace Loki
|
||
|
|
|
||
|
|
////////////////////////////////////////////////////////////////////////////////
|
||
|
|
// Change log:
|
||
|
|
// June 20, 2001: ported by Nick Thurn to gcc 2.95.3. Kudos, Nick!!!
|
||
|
|
// May 10, 2002: ported by Rani Sharoni to VC7 (RTM - 9466)
|
||
|
|
// Oct 28, 2002: ported by Benjamin Kaufmann
|
||
|
|
////////////////////////////////////////////////////////////////////////////////
|
||
|
|
|
||
|
|
#endif
|