record.hpp

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/*
  RECORD.hpp  -  collection to represent object-like data

  Copyright (C)         Lumiera.org
    2015,               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.

*/


#ifndef LIB_DIFF_RECORD_H
#define LIB_DIFF_RECORD_H


#include "lib/error.hpp"
#include "lib/nocopy.hpp"
#include "lib/iter-adapter.hpp"
#include "lib/iter-adapter-stl.hpp"
#include "lib/itertools.hpp"
#include "lib/format-util.hpp"        
#include "lib/util.hpp"


#include <algorithm>
#include <utility>
#include <vector>
#include <string>



namespace lib {
  
  template<class BA, class DEFAULT>
  class PlantingHandle;
  
namespace idi {
  class BareEntryID;
}
namespace diff{
  
  namespace error = lumiera::error;
  
  using util::isnil;
  using std::string;
  
  class TreeMutator;
  
  template<typename VAL>
  struct RecordSetup;
  
  
  template<typename VAL>
  class Record
    {
      using Storage  = typename RecordSetup<VAL>::Storage;
      using ElmIter  = typename RecordSetup<VAL>::ElmIter;
      using Access   = typename RecordSetup<VAL>::Access;
      
      
      string type_;
      Storage attribs_;
      Storage children_;
      
    public:
      static const string TYPE_NIL;
      static const Symbol TYPE_NIL_SYM;
      
      Record()
        : type_(TYPE_NIL)
        { }
      
      template<typename A, typename C>
      Record(Symbol typeID, A&& att, C&& chi)
        : type_(isnil(typeID)? TYPE_NIL:string(typeID))
        , attribs_(std::forward<A> (att))
        , children_(std::forward<C> (chi))
        { }
      
      template<typename A, typename C>
      Record(Symbol typeID, std::initializer_list<A> const&& att
                          , std::initializer_list<C> const&& chi)
        : type_(isnil(typeID)? TYPE_NIL:string(typeID))
        , attribs_(att)
        , children_(chi)
        { }
      
      template<typename SEQ>
      explicit
      Record (SEQ const& con)
        : type_(TYPE_NIL)
        {
          auto p = std::begin(con);
          auto e = std::end(con);
          for ( ; p!=e && isAttribute(*p); ++p)
            if (isTypeID (*p))
              type_ = extractTypeID(*p);
            else
              attribs_.push_back (*p);
          for ( ; p!=e; ++p)
            children_.push_back (*p);
        }
      
      Record (std::initializer_list<VAL> const&& ili)
        : Record(ili)
        { }
      
      // all default copy operations acceptable
      
      
      operator std::string()  const;
      
      
      size_t
      attribSize()  const
        {
          return attribs_.size();
        }
      
      size_t
      childSize()  const
        {
          return children_.size();
        }
      
      bool
      empty()  const
        {
          return attribs_.empty()
             and children_.empty();
        }
      
      
      string
      getType()  const
        {
          return type_;
        }
      
      bool
      hasAttribute (string key)  const
        {
          return attribs_.end() != findKey(key);
        }
      
      bool
      contains (VAL const& val)  const
        {
          return util::contains (children_, val);
        }
      
      Access
      get (string key)  const
        {
          ElmIter found = findKey (key);
          if (attribs_.end() == found)
            throw error::Invalid ("Record has no attribute \""+key+"\"");
          else
            return extractVal (*found);
        }
      
      Access
      child (size_t idx)  const
        {
          if (children_.size() <= idx)
            throw error::Invalid ("Child index "       +util::toString(idx)
                                 +" out of bounds [0.."+util::toString(children_.size())
                                 +"["
                                 ,error::LUMIERA_ERROR_INDEX_BOUNDS);
          return children_[idx];
        }
      
      
      class Mutator;
      
      
      
      Record (Mutator const& mut)
        : Record((Record const&) mut)
        { }
      explicit
      Record (Mutator && mut)
        : Record(std::move (Record(mut)))
        { }
      
      friend class Mutator;
      
      
      
      /* ==== Exposing scope and contents for iteration ====== */
      
      using iterator  = IterAdapter<ElmIter, const Record*>;
      using scopeIter = typename iter_stl::_SeqT<const Storage>::Range;
      using keyIter   = TransformIter<scopeIter, string>;
      using valIter   = TransformIter<scopeIter, Access>;
      
      iterator  begin ()  const { return iterator(this, attribs_.empty()? children_.begin() : attribs_.begin()); }
      iterator  end ()    const { return iterator(); }
      
      scopeIter attribs() const { return iter_stl::eachElm(attribs_); }
      scopeIter scope()   const { return iter_stl::eachElm(children_); }
      
      keyIter   keys()    const { return transformIterator(attribs(), extractKey); }
      valIter   vals()    const { return transformIterator(attribs(), extractVal); }
      
    protected: /* ==== API for the IterAdapter ==== */
      
      friend void
      iterNext (const Record*, ElmIter& pos)
        {
          ++pos;
        }
      
      friend bool
      checkPoint (const Record* src, ElmIter& pos)
        {
          REQUIRE (src);
          static const ElmIter END;
          if (pos != END && pos == src->attribs_.end() && !src->children_.empty())
            {
              pos = src->children_.begin();
              return true;
            }
          else
            if (pos != END && (pos != src->children_.end()))
              return true;
            else
              {
                pos = END;
                return false;
        }     }
      
    private:
      /* === abstract attribute handling : needs specialisation === */
      static bool   isAttribute (VAL const& v);
      static bool   isTypeID (VAL const& v);
      static string extractTypeID (VAL const& v);
      static string renderAttribute (VAL const& a);
      static string extractKey (VAL const& v);
      static Access extractVal (VAL const& v);
      template<typename X>
      static VAL    buildAttribute (string const& key, X&& payload);
      
      
      ElmIter
      findKey (string key)  const
        {
          return std::find_if (attribs_.begin()
                              ,attribs_.end()
                              ,[=](VAL const& elm)
                                   {
                                     return key == extractKey(elm);
                                   });
        }
      
      
      friend bool
      operator== (Record const& r1, Record const& r2)
      {
        return r1.type_ == r2.type_
           and r1.attribs_ == r2.attribs_
           and r1.children_ == r2.children_;
      }
      
      friend bool
      operator!= (Record const& r1, Record const& r2)
      {
        return not (r1 == r2);
      }
    };
  
  template<typename VAL>
  const Symbol Record<VAL>::TYPE_NIL_SYM = "NIL";
  
  template<typename VAL>
  const string Record<VAL>::TYPE_NIL = string(TYPE_NIL_SYM);
  
  
  
  template<typename VAL>
  class Record<VAL>::Mutator
    : util::MoveOnly
    {
      using Rec = Record<VAL>;
      
      Rec record_;
      
    public:
      Mutator()
        : record_()
        { }
      
      explicit
      Mutator (Rec const& startingPoint)
        : record_(startingPoint)
        { }
      
      explicit
      Mutator (Rec && startingPoint)
        : record_(std::move (startingPoint))
        { }
      
      operator Rec&()
        {
          return record_;
        }
      
      void
      swap (Rec& existingInstance)  noexcept
        {
          std::swap (existingInstance, record_);
        }
      
      bool
      empty()  const
        {
          return record_.empty();
        }
      
      
      /* === functions to alter contents === */
      
      void
      setType (string const& newTypeID)
        {
          record_.type_ = newTypeID;
        }
      
      Mutator&&
      type (string const& typeID)
        {
          setType (typeID);
          return move(*this);
        }
      
      template<typename X>
      Mutator&&
      set (string const& key, X&& content)
        {
          VAL attribute(Rec::buildAttribute (key, std::forward<X>(content)));
          return set (std::move (attribute));
        }
      
      Mutator&&
      set (VAL&& attribute)
        {
          string key = Rec::extractKey(attribute);
          if (isnil (key))
            throw error::Invalid ("Attempt to set an attribute with empty key");
          
          Rec::Storage& as =record_.attribs_;
          auto found = std::find_if (as.begin(),as.end()
                                    ,[=](VAL const& elm)
                                         {
                                           return key == extractKey(elm);
                                         });
          if (as.end() == found)
            as.push_back (std::forward<VAL> (attribute));
          else
            (*found) = (std::forward<VAL> (attribute));
          return move(*this);
        }
      
      Mutator&&
      appendAttrib (VAL const& newAttrib)
        {
          REQUIRE (Rec::isAttribute(newAttrib));
          record_.attribs_.push_back (newAttrib);
          return move(*this);
        }
      
      Mutator&&
      appendChild (VAL const& newChild)
        {
          record_.children_.push_back (newChild);
          return move(*this);
        }
      
      Mutator&&
      prependChild (VAL const& newChild)
        {
          record_.children_.insert (record_.children_.begin(), newChild);
          return move(*this);
        }
      
      /* === low-level access (for diff application) === */
      
      using BufferHandle = PlantingHandle<TreeMutator, TreeMutator>;
      
      void buildMutator (BufferHandle);
      
      auto
      exposeToDiff()
        {
          return std::tie (record_.attribs_, record_.children_);
        }
      
      
      VAL const&
      accessLast()
        {
          if (record_.empty())
            throw error::State("Record is empty, unable to access (last) element.");
          
          if (record_.children_.empty())
            return record_.attribs_.back();
          else
            return record_.children_.back();
        }
      
      
      /* === extension point for building specific value types === */
      /*
       * the following builder functions need to be specialised
       * to create a Record holding specific value types,
       * especially for building a tree like structure
       * with GenNode holding a Record<GenNode>
       */
      
      VAL genNode();
      VAL genNode(idi::BareEntryID rawID);
      VAL genNode(string const& symbolicID);
      
      template<typename X, typename...ARGS>
      Mutator&& attrib (string const& key, X&& initialiser, ARGS&& ...args)
        {
          set (key, std::forward<X>(initialiser));
          return attrib (std::forward<ARGS>(args)...);
        }
      Mutator&& attrib () { return move(*this); } // argument recursion end
      
      
      template<typename X, typename...ARGS>
      Mutator&& scope (X const& initialiser, ARGS&& ...args)
        {
          appendChild (VAL(initialiser));
          return scope (std::forward<ARGS>(args)...);
        }
      Mutator&& scope () { return move(*this); }
      
    };
  
  
  template<typename VAL>
  inline typename Record<VAL>::Mutator&
  mutateInPlace (Record<VAL>& record_to_mutate)
  {
    return reinterpret_cast<typename Record<VAL>::Mutator &> (record_to_mutate);
  }
  
  
  template<typename VAL>
  class RecordRef
    {
      using Target = Record<VAL>;
      
      Target* record_;
      
    public:
      RecordRef()  noexcept
        : record_(nullptr)
        { }
      
      RecordRef(Target& o)  noexcept
        : record_(&o)
        { }
      
      RecordRef(Target&&) = delete;
      
      RecordRef(RecordRef const&)  = default;
      RecordRef(RecordRef     &&)  = default;
      
      RecordRef& operator= (RecordRef const&)  = delete;
      RecordRef& operator= (RecordRef      &)  = delete;
      
      RecordRef&
      operator= (RecordRef &&o)
        {
          std::swap(record_, o.record_);
          return *this;
        }
      
      
      explicit
      operator bool()  const
        {
          return bool(record_);
        }
      
      bool
      empty()  const
        {
          return not record_;
        }
      
      operator Target&()  const
        {
          if (!record_)
            throw error::Logic("attempt to dereference an unbound record reference"
                              ,error::LUMIERA_ERROR_BOTTOM_VALUE);
          return *record_;
        }
      
      Target*
      get()  const noexcept
        {
          return record_;
        }
      
      operator string()  const
        {
          return "Ref->" + (empty()? util::BOTTOM_INDICATOR
                                   : string(*record_));
        }
      
      friend bool
      operator== (RecordRef const& r1, RecordRef const& r2)
      {
        return r1.record_ == r2.record_;
      }
      friend bool
      operator!= (RecordRef const& r1, RecordRef const& r2)
      {
        return r1.record_ != r2.record_;
      }
    };
  
  
  
  
  /* === Extension point: Specialisations for attribute handling === */
  
  template<>
  struct RecordSetup<string>
    {
      using Storage = std::vector<string>;
      using ElmIter = typename Storage::const_iterator;
      using Access  = string;      
    };
  
  
  
  
  /* default handling defined for Record<string> */
  
  template<>
  inline string
  Record<string>::extractKey (string const& v)
  {
    size_t pos = v.find('=');
    if (string::npos == pos)
      return "";
    else
      return util::trim (v.substr (0,pos));
  }
  
  template<>
  inline string
  Record<string>::extractVal (string const& v)
  {
    size_t pos = v.find('=');
    if (string::npos == pos)
      return v;
    else
      return util::trim (v.substr (pos+1, v.length() - pos));
  }
  
  template<>
  inline bool
  Record<string>::isAttribute (string const& v)
  {
    return string::npos != v.find('=');
  }
  
  template<>
  inline bool
  Record<string>::isTypeID (string const& v)
  {
    return isAttribute(v)
        && "type" == extractKey(v);
  }
  
  template<>
  inline string
  Record<string>::extractTypeID (string const& v)
  {
    return extractVal(v);
  }
  
  template<>
  inline string
  Record<string>::renderAttribute (string const& attrib)
  {
    return extractKey(attrib) + " = " + extractVal(attrib);
  }
  
  template<>
  template<typename X>
  inline string
  Record<string>::buildAttribute (string const& key, X&& payload)
  {
    return string(key + " = " + extractVal(payload));
  }
  
  
  
  
  
  
  /* === Diagnostics === */
  
  template<typename VAL>
  Record<VAL>::operator std::string()  const
  {
    using util::join;
    using lib::transformIterator;
    
    return "Rec("
         + (TYPE_NIL==type_? "" : type_)
         + (isnil(this->attribs())? "" : "| "+join (transformIterator (this->attribs(), renderAttribute))+" ")
         + (isnil(this->scope())?   "" : "|{"+join (this->scope())+"}")
         + ")"
         ;
  }
  
  
  
}} // namespace lib::diff
#endif /*LIB_DIFF_GEN_NODE_H*/