156 lines
5.5 KiB
C++
156 lines
5.5 KiB
C++
/*
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COMMAND-SIGNATURE.hpp - deriving suitable command function signatures
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Copyright (C) Lumiera.org
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2009, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/** @file command-signature.hpp
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** Metaprogramming helpers for deriving the precise function signatures
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** necessary to implement a given command. Basically, commands can be implemented
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** by arbitrary functions, but the signatures of the operation function, the
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** undo function and the undo state capturing function are required to obey
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** fixed relationships. Thus, at various stages of the command definition,
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** we need to accept functor objects with a very specific and predetermined
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** signature, thus allowing for strict type checking by the compiler.
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**
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** \par Relation of function signatures
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** - operation: void(P1,..PN)
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** - captureUndo: MEM(P1,..PN)
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** - undoOperation void(P1,..PN,MEM)
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** - bind takes the arguments:(P1,..PN)
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**
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** @see Command
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** @see CommandDef
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**
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*/
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#ifndef CONTROL_COMMAND_SIGNATURE_H
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#define CONTROL_COMMAND_SIGNATURE_H
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//#include "pre.hpp"
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//#include "include/symbol.hpp"
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#include "lib/meta/function.hpp"
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#include "lib/meta/typelist.hpp"
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#include "lib/meta/typelist-util.hpp"
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#include "lib/meta/typeseq-util.hpp"
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//#include "lib/meta/tuple.hpp"
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//#include <tr1/memory>
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#include <tr1/functional>
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namespace control {
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// using lumiera::Symbol;
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// using std::tr1::shared_ptr;
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using std::tr1::function;
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using lumiera::typelist::FunctionSignature;
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using lumiera::typelist::FunctionTypedef;
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using lumiera::typelist::Types;
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//using lumiera::typelist::NullType;
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//using lumiera::typelist::Tuple;
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using lumiera::typelist::Append;
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using lumiera::typelist::SplitLast;
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/**
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* Metaprogramming helper for building Command function signatures.
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* The complete definition context of any command is templated to the signature
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* of the actual command operation and to the memento type. The typedefs embedded
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* within CommandSignature<SIG,MEM> allows accepting suitable typed functions
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* to implement the command in question.
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*/
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template<typename SIG, typename MEM>
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class CommandSignature
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{
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typedef typename FunctionSignature< function<SIG> >::Args Args;
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typedef typename Args::List ArgList;
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typedef typename Append<ArgList, MEM>::List ExtendedArglist;
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typedef typename Types<ExtendedArglist>::Seq ExtendedArgs;
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public:
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typedef typename FunctionTypedef<void, Args>::Sig OperateSig;
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typedef typename FunctionTypedef<MEM, Args>::Sig CaptureSig;
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typedef typename FunctionTypedef<void, ExtendedArgs>::Sig UndoOp_Sig;
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typedef Args CmdArgs;
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typedef MEM Memento;
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};
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/**
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* Type analysis helper template.
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* Used for dissecting a given type signature to derive
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* the related basic operation signature, the signature of a possible Undo-function
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* and the signature necessary for capturing undo information. The implementation
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* relies on re-binding an embedded type defining template, based on the actual
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* case, as identified by the structure of the given parameter signature.
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*/
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template<typename SIG>
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class UndoSignature
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{
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typedef typename FunctionSignature< function<SIG> >::Args Args;
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typedef typename FunctionSignature< function<SIG> >::Ret Ret;
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/** Case1: defining the Undo-Capture function */
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template<typename RET, typename ARG>
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struct Case
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{
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typedef RET Memento;
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typedef typename Append<ARG, Memento>::List ExtendedArglist;
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typedef typename Types<ExtendedArglist>::Seq ExtendedArgs;
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typedef typename FunctionTypedef<void, ARG>::Sig OperateSig;
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typedef typename FunctionTypedef<Ret,ARG>::Sig CaptureSig;
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typedef typename FunctionTypedef<void, ExtendedArgs>::Sig UndoOp_Sig;
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};
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/** Case2: defining the actual Undo function */
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template<typename ARG>
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struct Case<void,ARG>
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{
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typedef typename ARG::List Args;
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typedef typename SplitLast<Args>::Type Memento;
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typedef typename SplitLast<Args>::List OperationArglist;
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typedef typename Types<OperationArglist>::Seq OperationArgs;
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typedef typename FunctionTypedef<void, OperationArgs>::Sig OperateSig;
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typedef typename FunctionTypedef<Ret,OperationArgs>::Sig CaptureSig;
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typedef typename FunctionTypedef<void, ARG>::Sig UndoOp_Sig;
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};
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public:
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typedef typename Case<Ret,Args>::CaptureSig CaptureSig;
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typedef typename Case<Ret,Args>::UndoOp_Sig UndoOp_Sig;
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typedef typename Case<Ret,Args>::OperateSig OperateSig;
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typedef typename Case<Ret,Args>::Memento Memento;
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};
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} // namespace control
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#endif
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