diff-language.hpp

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/*
  DIFF-LANGUAGE.hpp  -  language to describe differences in linearised form

   Copyright (C)
     2014,            Hermann Vosseler <Ichthyostega@web.de>

  **Lumiera** 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. See the file COPYING for further details.

*/


#ifndef LIB_DIFF_DIFF_LANGUAGE_H
#define LIB_DIFF_DIFF_LANGUAGE_H


#include "lib/error.hpp"
#include "lib/nocopy.hpp"
#include "lib/verb-token.hpp"
#include "lib/util.hpp"

#include <tuple>


namespace lumiera {
namespace error {
  LUMIERA_ERROR_DECLARE(DIFF_STRUCTURE); 
  LUMIERA_ERROR_DECLARE(DIFF_CONFLICT); 
}}

namespace lib {
namespace diff{
  
  namespace error = lumiera::error;
  
  
  template<class I, typename E>
  using HandlerFun = void (I::*) (E const&); // NOTE: element value taken by const&
  
  
  template<class I>
  struct InterpreterScheme               
    {
      using Interpreter = I;
      using Val = typename I::Val;
      using Handler = HandlerFun<I,Val>;
    };
  
  template<template<typename> class IP, typename E>
  struct InterpreterScheme<IP<E>>        
    {
      using Val = E;
      using Interpreter = IP<E>;
      using Handler = HandlerFun<Interpreter,Val>;
    };
  
  template<class I, typename E>          
  struct InterpreterScheme<HandlerFun<I,E>>
    {
      using Val = E;
      using Interpreter = I;
      using Handler = HandlerFun<I,E>;
    };
  
  
  
  template< class I, typename E>
  struct DiffLanguage
    {
      
      using DiffVerb = VerbToken<I, void(E const&)>; // NOTE: element value taken by const&
      using DiffToken = std::tuple<DiffVerb, E>;
      using Interpreter = I;
      
      struct DiffStep
        : DiffToken
        {
          DiffVerb& verb() { return std::get<0>(*this); }
          E const&  elm()  { return std::get<1>(*this); }
          
          DiffStep(DiffVerb verb, E e)
            : DiffToken(verb,e)
            { }
          
          operator string()  const
            {
              return string(unConst(this)->verb())
               + "("+string(unConst(this)->elm())+")";
            }
          
          void
          applyTo (Interpreter& interpreter)
            {
              TRACE (diff, "verb %4s(%s)", cStr(verb()), cStr(elm()) );
              verb().applyTo (interpreter, elm());
            }
        };
      
      
      static const DiffStep NIL;
    };
  
  
  
  
  
  template<class I>
  struct DiffStepBuilder
    {
      using Scheme  = InterpreterScheme<I>;
      using Handler = typename Scheme::Handler;
      using Val     = typename Scheme::Val;
      
      using Lang = DiffLanguage<I,Val>;
      using Step = typename Lang::DiffStep;
      using Verb = typename Lang::DiffVerb;
      
      Handler handler;
      Literal id;
      
      Step
      operator() (Val elm)  const
        {
          return { Verb(handler,id), elm };
        }
    };
  
  
  template<class H>
  inline DiffStepBuilder<typename InterpreterScheme<H>::Interpreter>
  diffTokenBuilder (H handlerFun, Literal id)
  {
    return { handlerFun, id };
  }
  
#define DiffStep_CTOR(_ID_) \
  const DiffStepBuilder<Interpreter> _ID_ = diffTokenBuilder (&Interpreter::_ID_, STRINGIFY(_ID_));
  
  
  
  template<class I, typename E>
  const typename DiffLanguage<I,E>::DiffStep DiffLanguage<I,E>::NIL = DiffStep(DiffVerb(), E());
  
  
  
  
  
  
  
  
  
  /* ==== Implementation Pattern for Diff Application ==== */
  
  template<class TAR, typename SEL =void>
  class DiffApplicationStrategy;
  
  
  template<class TAR>
  class DiffApplicator
    : util::NonCopyable
    {
      using Interpreter = DiffApplicationStrategy<TAR>;
      
      Interpreter target_;
      
    public:
      explicit
      DiffApplicator(TAR& targetStructure)
        : target_(targetStructure)
        { }
      
      template<class DIFF>
      void
      consume (DIFF&& diff)
        {
          target_.initDiffApplication();
          for ( ; diff; ++diff )
            diff->applyTo(target_);
          target_.completeDiffApplication();
        }
    };
  
  
  
}} // namespace lib::diff
#endif /*LIB_DIFF_DIFF_LANGUAGE_H*/