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add support for visiting constant member functions

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git-svn-id: svn://svn.code.sf.net/p/loki-lib/code/trunk@391 7ec92016-0320-0410-acc4-a06ded1c099a
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syntheticpp 2006-01-02 10:36:45 +00:00
parent 40bd3305fb
commit d25cf66827
1 changed files with 76 additions and 15 deletions
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91
include/loki/Visitor.h
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@ -13,7 +13,7 @@
// without express or implied warranty.
////////////////////////////////////////////////////////////////////////////////
// Last update: June 20, 2001
// $Header:
#ifndef LOKI_VISITOR_INC_
#define LOKI_VISITOR_INC_
@ -40,14 +40,27 @@ namespace Loki
// The building block of Acyclic Visitor
////////////////////////////////////////////////////////////////////////////////
template <class T, typename R = void>
class Visitor
template <class T, typename R = void, bool ConstVisit = false>
class Visitor;
template <class T, typename R>
class Visitor<T, R, false>
{
public:
typedef R ReturnType;
virtual ReturnType Visit(T&) = 0;
typedef T ParamType;
virtual ReturnType Visit(ParamType&) = 0;
};
template <class T, typename R>
class Visitor<T, R, true>
{
public:
typedef R ReturnType;
typedef const T ParamType;
virtual ReturnType Visit(ParamType&) = 0;
};
////////////////////////////////////////////////////////////////////////////////
// class template Visitor (specialization)
// This specialization is not present in the book. It makes it easier to define
@ -55,8 +68,7 @@ namespace Loki
//
// class SomeVisitor :
// public BaseVisitor // required
// public Visitor<LOKI_TYPELIST_2(RasterBitmap, Paragraph)>,
// public Visitor<Paragraph>
// public Visitor<LOKI_TYPELIST_2(RasterBitmap, Paragraph)>
// {
// public:
// void Visit(RasterBitmap&); // visit a RasterBitmap
@ -65,8 +77,8 @@ namespace Loki
////////////////////////////////////////////////////////////////////////////////
template <class Head, class Tail, typename R>
class Visitor<Typelist<Head, Tail>, R>
: public Visitor<Head, R>, public Visitor<Tail, R>
class Visitor<Typelist<Head, Tail>, R, false>
: public Visitor<Head, R, false>, public Visitor<Tail, R, false>
{
public:
typedef R ReturnType;
@ -75,13 +87,32 @@ namespace Loki
};
template <class Head, typename R>
class Visitor<Typelist<Head, NullType>, R> : public Visitor<Head, R>
class Visitor<Typelist<Head, NullType>, R, false> : public Visitor<Head, R, false>
{
public:
typedef R ReturnType;
using Visitor<Head, R>::Visit;
using Visitor<Head, R, false>::Visit;
};
template <class Head, class Tail, typename R>
class Visitor<Typelist<Head, Tail>, R, true>
: public Visitor<Head, R, true>, public Visitor<Tail, R, true>
{
public:
typedef R ReturnType;
// using Visitor<Head, R>::Visit;
// using Visitor<Tail, R>::Visit;
};
template <class Head, typename R>
class Visitor<Typelist<Head, NullType>, R, true> : public Visitor<Head, R, true>
{
public:
typedef R ReturnType;
using Visitor<Head, R, true>::Visit;
};
////////////////////////////////////////////////////////////////////////////////
// class template BaseVisitorImpl
// Implements non-strict visitation (you can implement only part of the Visit
@ -129,9 +160,13 @@ struct DefaultCatchAll
template
<
typename R = void,
template <typename, class> class CatchAll = DefaultCatchAll
template <typename, class> class CatchAll = DefaultCatchAll,
bool ConstVisitable = false
>
class BaseVisitable
class BaseVisitable;
template<typename R,template <typename, class> class CatchAll>
class BaseVisitable<R, CatchAll, false>
{
public:
typedef R ReturnType;
@ -151,6 +186,27 @@ struct DefaultCatchAll
}
};
template<typename R,template <typename, class> class CatchAll>
class BaseVisitable<R, CatchAll, true>
{
public:
typedef R ReturnType;
virtual ~BaseVisitable() {}
virtual ReturnType Accept(BaseVisitor&) const = 0;
protected: // give access only to the hierarchy
template <class T>
static ReturnType AcceptImpl(const T& visited, BaseVisitor& guest)
{
// Apply the Acyclic Visitor
if (Visitor<T,R,true>* p = dynamic_cast<Visitor<T,R,true>*>(&guest))
{
return p->Visit(visited);
}
return CatchAll<R, T>::OnUnknownVisitor(const_cast<T&>(visited), guest);
}
};
////////////////////////////////////////////////////////////////////////////////
// macro DEFINE_VISITABLE
// Put it in every class that you want to make visitable (in addition to
@ -161,6 +217,10 @@ struct DefaultCatchAll
virtual ReturnType Accept(::Loki::BaseVisitor& guest) \
{ return AcceptImpl(*this, guest); }
#define LOKI_DEFINE_CONST_VISITABLE() \
virtual ReturnType Accept(::Loki::BaseVisitor& guest) const \
{ return AcceptImpl(*this, guest); }
////////////////////////////////////////////////////////////////////////////////
// class template CyclicVisitor
// Put it in every class that you want to make visitable (in addition to
@ -195,9 +255,10 @@ struct DefaultCatchAll
////////////////////////////////////////////////////////////////////////////////
// Change log:
// March 20: add default argument DefaultCatchAll to BaseVisitable
// June 20, 2001: ported by Nick Thurn to gcc 2.95.3. Kudos, Nick!!!
// March 20, ????: add default argument DefaultCatchAll to BaseVisitable
// June 20, 2001: ported by Nick Thurn to gcc 2.95.3. Kudos, Nick!!!
// September 28, 2004: replaced Loki:: with ::Loki:: in DEFINE_VISITABLE
// January 2, 2006: add support for visiting constant member functions, Peter Kümmel
////////////////////////////////////////////////////////////////////////////////
#endif // VISITOR_INC_