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+/* vim: set sw=4 sts=4 et foldmethod=syntax : */
+
+/*
+ * Copyright (c) 2008, 2009, 2010, 2011 Ciaran McCreesh
+ *
+ * This file is part of the Paludis package manager. Paludis is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU General
+ * Public License version 2, as published by the Free Software Foundation.
+ *
+ * Paludis is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef PALUDIS_GUARD_PALUDIS_UTIL_VISITOR_HH
+#define PALUDIS_GUARD_PALUDIS_UTIL_VISITOR_HH 1
+
+#include <paludis/util/visitor-fwd.hh>
+#include <paludis/util/no_type.hh>
+
+namespace paludis
+{
+ template <>
+ struct DeclareAbstractVisitMethods<TypeListTail>
+ {
+ void forward_visit(const NoType<0u> &);
+ };
+
+ template <typename TypeList_>
+ class DeclareAbstractVisitMethods :
+ public virtual DeclareAbstractVisitMethods<typename TypeList_::Tail>
+ {
+ public:
+ using DeclareAbstractVisitMethods<typename TypeList_::Tail>::forward_visit;
+
+ virtual void forward_visit(typename TypeList_::Item &) = 0;
+ };
+
+ template <typename TypeList_>
+ class WrappedVisitorBase :
+ public virtual DeclareAbstractVisitMethods<TypeList_>
+ {
+ };
+
+ template <typename RealClass_>
+ class ImplementVisitMethods<RealClass_, TypeListTail>
+ {
+ public:
+ void forward_visit(const NoType<1u> &);
+ };
+
+ template <typename RealClass_, typename TypeList_>
+ class ImplementVisitMethods :
+ public virtual DeclareAbstractVisitMethods<TypeList_>,
+ public ImplementVisitMethods<RealClass_, typename TypeList_::Tail>
+ {
+ public:
+ using ImplementVisitMethods<RealClass_, typename TypeList_::Tail>::forward_visit;
+
+ virtual void forward_visit(typename TypeList_::Item & n)
+ {
+ /* avoid gcc being too clever about noreturn */
+ if (this)
+ static_cast<RealClass_ *>(this)->perform_visit(n);
+ }
+ };
+
+ template <typename TypeList_, typename UnwrappedVisitor_>
+ class WrappedVoidResultVisitor :
+ public WrappedVisitorBase<TypeList_>,
+ public ImplementVisitMethods<WrappedVoidResultVisitor<TypeList_, UnwrappedVisitor_>, TypeList_>
+ {
+ private:
+ UnwrappedVisitor_ & _unwrapped_visitor;
+
+ public:
+ WrappedVoidResultVisitor(UnwrappedVisitor_ & v) :
+ _unwrapped_visitor(v)
+ {
+ }
+
+ template <typename C_>
+ void perform_visit(C_ & t)
+ {
+ _unwrapped_visitor.visit(t);
+ }
+ };
+
+ template <typename TypeList_, typename Result_, typename UnwrappedVisitor_>
+ class WrappedNonVoidResultVisitor :
+ public WrappedVisitorBase<TypeList_>,
+ public ImplementVisitMethods<WrappedNonVoidResultVisitor<TypeList_, Result_, UnwrappedVisitor_>,
+ TypeList_>
+ {
+ private:
+ UnwrappedVisitor_ & _unwrapped_visitor;
+
+ public:
+ Result_ result;
+
+ WrappedNonVoidResultVisitor(UnwrappedVisitor_ & v, const Result_ & r) :
+ _unwrapped_visitor(v),
+ result(r)
+ {
+ }
+
+ template <typename C_>
+ void perform_visit(C_ & t)
+ {
+ result = _unwrapped_visitor.visit(t);
+ }
+ };
+
+ template <typename BaseClass_, typename VisitableTypeList_>
+ class DeclareAbstractAcceptMethods
+ {
+ private:
+ virtual void _real_accept(WrappedVisitorBase<VisitableTypeList_> &) = 0;
+ virtual void _real_accept_const(WrappedVisitorBase<typename MakeTypeListConst<VisitableTypeList_>::Type> &) const = 0;
+
+ public:
+ typedef VisitableTypeList_ VisitableTypeList;
+ typedef BaseClass_ VisitableBaseClass;
+
+ template <typename UnwrappedVisitor_>
+ void accept(UnwrappedVisitor_ & v)
+ {
+ WrappedVoidResultVisitor<VisitableTypeList_, UnwrappedVisitor_> vv(v);
+ _real_accept(vv);
+ }
+
+ template <typename UnwrappedVisitor_>
+ void accept(UnwrappedVisitor_ & v) const
+ {
+ WrappedVoidResultVisitor<typename MakeTypeListConst<VisitableTypeList_>::Type, UnwrappedVisitor_> vv(v);
+ _real_accept_const(vv);
+ }
+
+ template <typename UnwrappedVisitor_>
+ void accept(const UnwrappedVisitor_ & v)
+ {
+ WrappedVoidResultVisitor<VisitableTypeList_, const UnwrappedVisitor_> vv(v);
+ _real_accept(vv);
+ }
+
+ template <typename UnwrappedVisitor_>
+ void accept(const UnwrappedVisitor_ & v) const
+ {
+ WrappedVoidResultVisitor<typename MakeTypeListConst<VisitableTypeList_>::Type, const UnwrappedVisitor_> vv(v);
+ _real_accept_const(vv);
+ }
+
+ template <typename Result_, typename UnwrappedVisitor_>
+ Result_ accept_returning(UnwrappedVisitor_ & v, const Result_ & r = Result_())
+ {
+ WrappedNonVoidResultVisitor<VisitableTypeList_, Result_, UnwrappedVisitor_> vv(v, r);
+ _real_accept(vv);
+ return vv.result;
+ }
+
+ template <typename Result_, typename UnwrappedVisitor_>
+ Result_ accept_returning(const UnwrappedVisitor_ & v, const Result_ & r = Result_())
+ {
+ WrappedNonVoidResultVisitor<VisitableTypeList_, Result_, const UnwrappedVisitor_> vv(v, r);
+ _real_accept(vv);
+ return vv.result;
+ }
+
+ template <typename Result_, typename UnwrappedVisitor_>
+ Result_ accept_returning(UnwrappedVisitor_ & v, const Result_ & r = Result_()) const
+ {
+ WrappedNonVoidResultVisitor<typename MakeTypeListConst<VisitableTypeList_>::Type, Result_, UnwrappedVisitor_> vv(v, r);
+ _real_accept_const(vv);
+ return vv.result;
+ }
+
+ template <typename Result_, typename UnwrappedVisitor_>
+ Result_ accept_returning(const UnwrappedVisitor_ & v, const Result_ & r = Result_()) const
+ {
+ WrappedNonVoidResultVisitor<typename MakeTypeListConst<VisitableTypeList_>::Type, Result_, const UnwrappedVisitor_> vv(v, r);
+ _real_accept_const(vv);
+ return vv.result;
+ }
+ };
+
+ template <typename BaseClass_, typename RealClass_>
+ class ImplementAcceptMethods :
+ public virtual DeclareAbstractAcceptMethods<BaseClass_, typename BaseClass_::VisitableTypeList>
+ {
+ private:
+ void _real_accept(WrappedVisitorBase<typename BaseClass_::VisitableTypeList> & v)
+ {
+ v.forward_visit(*static_cast<RealClass_ *>(this));
+ };
+
+ void _real_accept_const(WrappedVisitorBase<typename MakeTypeListConst<typename BaseClass_::VisitableTypeList>::Type> & v) const
+ {
+ v.forward_visit(*static_cast<const RealClass_ *>(this));
+ };
+ };
+}
+
+#endif