101 lines
3.5 KiB
C++
101 lines
3.5 KiB
C++
/*
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LIST-DIFF.hpp - language to describe differences between list like sequences
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Copyright (C) Lumiera.org
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2014, 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 list-diff.hpp
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** A token language to represent changes in a list of elements.
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** In combination with the #DiffLanguage framework, this building block
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** defines the set of operations to express changes in a given list of elements.
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** By implementing the #ListDiffInterpreter interface (visitor), a concrete usage
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** can receive such a diff description and e.g. apply it to a target data structure.
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**
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** @see diff-language.cpp
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** @see diff-list-application-test.cpp
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** @see VerbToken
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**
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*/
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#ifndef LIB_DIFF_LIST_DIFF_H
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#define LIB_DIFF_LIST_DIFF_H
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#include "lib/diff/diff-language.hpp"
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namespace lib {
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namespace diff{
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/**
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* Interpreter interface to define the operations ("verbs"),
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* which describe differences or changes in a given list of data elements.
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* The meaning of the verbs is as follows:
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* - \c ins prompts to insert the given argument element at the \em current
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* processing position into the target sequence. This operation
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* allows to inject new data
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* - \c del requires to delete the \em next element at \em current position.
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* For sake of verification, the element to be deleted is also
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* included as argument (redundancy).
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* - \c pick just accepts the \em next element at \em current position into
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* the resulting altered sequence. The element is given redundantly.
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* - \c find effect a re-ordering of the target list contents: it requires
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* to \em search for the (next respective single occurrence of the)
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* given element further down into the remainder of the list,
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* to bring it forward and insert it as the next element.
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* - \c skip processing hint, emitted at the position where an element
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* previously extracted by a \c find verb happened to sit within
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* the old order. This allows an optimising implementation to “fetch”
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* a copy and just drop or skip the original, thereby avoiding to
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* shift any other elements.
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*/
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template<typename E>
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class ListDiffInterpreter
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{
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public:
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virtual ~ListDiffInterpreter() { } ///< this is an interface
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virtual void ins(E e) =0;
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virtual void del(E e) =0;
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virtual void pick(E e) =0;
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virtual void find(E e) =0;
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virtual void skip(E e) =0;
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};
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template<typename E>
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struct ListDiffLanguage
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: DiffLanguage<ListDiffInterpreter<E>, E>
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{
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using Interpreter = ListDiffInterpreter<E>;
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DiffStep_CTOR(ins);
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DiffStep_CTOR(del);
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DiffStep_CTOR(pick);
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DiffStep_CTOR(find);
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DiffStep_CTOR(skip);
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};
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}} // namespace lib::diff
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#endif /*LIB_DIFF_LIST_DIFF_H*/
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