tree-diff-application.hpp

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/*
  TREE-DIFF-APPLICATION.hpp  -  consume and apply a tree diff

   Copyright (C)
     2016,            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_TREE_DIFF_APPLICATION_H
#define LIB_DIFF_TREE_DIFF_APPLICATION_H


#include "lib/diff/tree-diff.hpp"
#include "lib/diff/tree-mutator.hpp"
#include "lib/diff/diff-mutable.hpp"
#include "lib/diff/tree-diff-traits.hpp"
#include "lib/diff/gen-node.hpp"
#include "lib/format-string.hpp"
#include "lib/util.hpp"

#include <utility>
#include <stack>

namespace lib {
namespace diff{
  
  class ScopeManager
    : util::NonCopyable
    {
    public:
      virtual ~ScopeManager();  
      
      virtual TreeMutator::Handle openScope()   =0;      
      virtual TreeMutator&        closeScope()  =0;
      virtual void                clear()       =0;
      
      virtual size_t depth()  const             =0;
    };
  
  
  
  template<size_t buffSiz>
  class StackScopeManager
    : public ScopeManager
    {
      using MutatorBuffer = InPlaceBuffer<TreeMutator, buffSiz>;
      using MutatorStack = std::stack<MutatorBuffer>;
      
      MutatorStack scopes_;
      
      
    public:
      StackScopeManager()
        : scopes_()
        { }
      
      TreeMutator&
      currentScope()  const
        {
          if (0 == depth())
            throw error::Logic("Attempt to access the current scope "
                               "without establishing a root scope beforehand."
                              , error::LUMIERA_ERROR_LIFECYCLE);
          return *scopes_.top();
        }
      
      
      /* ==== ScopeManager interface ==== */
      
      virtual TreeMutator::Handle
      openScope()
        {
          scopes_.emplace();
          TreeMutator::Handle placementHandle (scopes_.top());
          return placementHandle;
        }
      
      virtual TreeMutator&
      closeScope()
        {
          scopes_.pop();
          REQUIRE (0 < depth(), "attempt to return beyond root scope");
          return *scopes_.top();
        }
      
      virtual void
      clear()
        {
          while (0 < scopes_.size())
            scopes_.pop();
          
          ENSURE (scopes_.empty());
        }

      
      virtual size_t
      depth()  const
        {
          return scopes_.size();
        }
    };
  
  
  
  
  
  /* ======= Implementation of Tree Diff Application via TreeMutator ======= */
  
  using util::unConst;
  using util::_Fmt;
  using std::move;
  using std::swap;
  
  
  class TreeDiffMutatorBinding
    : public TreeDiffInterpreter
    {
    protected:
      TreeMutator*  treeMutator_;
      ScopeManager* scopeManger_;
      
    private:
      
      /* == error handling helpers == */
      
      void __failMismatch (Literal oper, GenNode const& spec);
      void __expect_further_elements (GenNode const& elm);
      void __fail_not_found (GenNode const& elm);
      void __expect_end_of_scope (GenNode::ID const& idi);
      void __expect_valid_parent_scope (GenNode::ID const& idi);
      
      
      
      
      /* == Implementation of the list diff application primitives == */
      
      virtual void ins  (GenNode const& n) override;
      virtual void del  (GenNode const& n) override;
      virtual void pick (GenNode const& n) override;
      virtual void skip (GenNode const& n) override;
      virtual void find (GenNode const& n) override;
      
      
      /* == Implementation of the tree diff application primitives == */
      
      virtual void after(GenNode const& n) override;
      virtual void set  (GenNode const& n) override;
      virtual void mut  (GenNode const& n) override;
      virtual void emu  (GenNode const& n) override;
      
      
    public:
      TreeDiffMutatorBinding()
        : treeMutator_(nullptr)
        , scopeManger_(nullptr)
        { }
    };
  
  
  
  
  
  
  template<class TAR>
  class DiffApplicationStrategy<TAR,  enable_if<TreeDiffTraits<TAR>>>
    : public TreeDiffMutatorBinding
    {
      using Scopes = StackScopeManager<TreeMutatorSizeTraits<TAR>::siz>;
      
      
      TAR& subject_;
      Scopes scopes_;
      
      
      TreeMutator*
      buildMutator (DiffMutable& targetBinding)
        {
          scopes_.clear();
          TreeMutator::Handle buffHandle = scopes_.openScope();
          targetBinding.buildMutator (buffHandle);
          return buffHandle.get();
        }
      
    public:
      explicit
      DiffApplicationStrategy(TAR& subject)
        : TreeDiffMutatorBinding()
        , subject_(subject)
        , scopes_()
        { }
      
      void
      initDiffApplication()
        {
          using Target = typename TreeDiffTraits<TAR>::Ret;
          
          Target target = mutatorBinding (subject_);
          buildMutator(target)->init();
          TreeDiffMutatorBinding::scopeManger_ = &scopes_;
          TreeDiffMutatorBinding::treeMutator_ = &scopes_.currentScope();
          REQUIRE (this->treeMutator_);
        }
      
      void
      completeDiffApplication()
        {
          if (not treeMutator_->completeScope())
            throw error::State(_Fmt("Unsettled content remains after diff application. "
                                    "Top level == %s") % subject_
                              , LERR_(DIFF_STRUCTURE));
          // discard storage
          treeMutator_ = nullptr;
          scopes_.clear();
        }
    };
  
  
  
}} // namespace lib::diff
#endif /*LIB_DIFF_TREE_DIFF_APPLICATION_H*/