LUMIERA.clone/src/lib/advice/binding.hpp

120 lines
4.2 KiB
C++

/*
BINDING.hpp - pattern defining a specific attachment to the Advice system
Copyright (C) Lumiera.org
2010, Hermann Vosseler <Ichthyostega@web.de>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
This program 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/** @file binding.hpp
** A pattern to define and identify a specific attachment to the Advice system.
** This pattern is comprised of a predicate list and intended to be matched or unified
** against a similar pattern associated with the attachment of a possible collaboration partner.
** Semantically, this list of atoms forms an conjunction of predicates to be resolved against
** similar predicates of the partner. Informally, when two entities attach to the Advice system,
** each specifying a binding, they can be paired up if, when combining, the expressions in their
** bindings all evaluate to true.
**
** Typically, a binding includes a \em type-guard predicate \c adviceType(xx) where \c xx is an
** identifier denoting a type used within an instantiation of the Advice collaboration, i.e. a type
** used as advice value in a instantiation of the PointOfAdvice<AD> template. Besides the type guard,
** a binding may narrow down the topic of the advice by providing further predicates. This allows for
** Advice collaborations targeted at a more specific topic. The goal and intention behind this Advice
** system is to allow collaboration of entities without requiring them to be tightly coupled. Indeed,
** the only dependency besides the common type used as advice is to know any specific topic used
** within the binding. Thus, and advisor entity could put up a piece of advice, i.e. a value of
** the advice type, and another client entity (the advised entity) could pick up this value
** without the need to now anything about the advisor.
**
** Any binding can be normalised into a hash value, which plays a crucial role within the
** implementation of the advice system.
**
** TODO WIP-WIP
**
** @note as of 4/2010 this is an experimental setup and implemented just enough to work out
** the interfaces. Ichthyo expects this collaboration service to play a central role
** at various places within proc-layer.
**
** @see configrules.hpp
** @see typed-lookup.cpp corresponding implementation
** @see typed-id-test.cpp
**
*/
#ifndef LIB_ADVICE_BINDING_H
#define LIB_ADVICE_BINDING_H
#include "lib/error.hpp"
//#include "proc/asset.hpp"
//#include "proc/asset/struct-scheme.hpp"
//#include "lib/hash-indexed.hpp"
//#include "lib/util.hpp"
#include "lib/symbol.hpp"
//#include <boost/operators.hpp>
//#include <tr1/memory>
//#include <iostream>
#include <string>
namespace lib {
namespace advice {
using std::string;
/**
* Conjunction of predicates to be matched
* against a collaboration partner for establishing
* an Advice connection.
* TODO type comment
*/
class Binding
{
public:
/** create the empty binding, equivalent to \c true */
Binding();
/** create the binding as defined by the given textual definition.
* @note implicit type conversion deliberately intended */
Binding (Literal spec);
/*-- Binding is default copyable --*/
/** extend the definition of this binding
* by adding a predicate according to the
* given textual definition */
void addPredicate (Literal spec);
template<typename TY>
void addTypeGuard();
operator string() const;
};
////TODO define the hash function here, to be picked up by ADL
}} // namespace lib::advice
#endif