93 lines
3.6 KiB
C++
93 lines
3.6 KiB
C++
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/*
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DIFF-MUTABLE.hpp - interface for data structures mutable through diff message
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Copyright (C) Lumiera.org
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2016, 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
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the 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 diff-mutable.hpp
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** Abstraction or descriptor interface for a data structure
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** exposing the ability for mutation by receiving diff messages.
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** Differences and changes on such data structures can be specified in the form
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** of a "linearised diff language". Such a diff can be represented as a sequence
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** of tokens, describing the manipulations necessary to effect the desired change.
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** While, conceptually, such a diff is drawn against a generic tree like data
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** description (actually based on diff::Record<GenNode>), with the help of a
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** customisable intermediary binding layer, it is possible to apply such diff
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** messages onto data structures otherwise not further disclosed. For this to
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** work, the target data structure itself must offer the ability to construct
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** such a suitable intermediary binding layer. This interface declares and
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** offers this ability.
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**
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** A data structure exposing this interface in one way or the other (which
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** might be through the help of an ADL bound free function) thus offers some kind
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** of closure, which, when invoked, will build a concrete TreeMutator implementation
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** into the given working buffer. Obviously, this TreeMutator is then somehow opaquely
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** wired to the data structure so to be able to invoke transforming operations on
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** this target data. Here, the TreeMutator interface defines the primitive operations
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** necessary to apply a conforming diff message onto this otherwise private data
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** structure. Based on such a setup, client code may create a DiffApplicator
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** to embody this custom TreeMutator, which in the end allows to consume
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** diff messages, thereby transforming and mutating the target data
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** structure without the need to know any internal details.
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**
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** @see diff-language.hpp
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** @see tree-diff-application.hpp
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** @see diff-virtualised-application-test.cpp
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** @see TreeMutator
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**
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*/
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#ifndef LIB_DIFF_DIFF_MUTABLE_H
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#define LIB_DIFF_DIFF_MUTABLE_H
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#include "lib/diff/tree-mutator.hpp"
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namespace lib {
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namespace diff{
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/**
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* Marker or capability interface:
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* an otherwise not further disclosed data structure,
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* which can be transformed through "tree diff messages"
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*/
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class DiffMutable
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{
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public:
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virtual ~DiffMutable() { } ///< this is an interface
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/** build a custom implementation of the TreeMutator interface,
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* suitably wired to cause appropriate changes to the opaque
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* data structure, in accordance to the semantics of the
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* tree diff language.
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* @param a buffer handle, which can be used to placement-construct
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*/
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virtual void buildMutator (TreeMutator::Handle) =0;
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};
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}} // namespace lib::diff
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#endif /*LIB_DIFF_DIFF_MUTABLE_H*/
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