iter-adapter-stl.hpp

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/*
  ITER-ADAPTER-STL.hpp  -  helpers for building simple forward iterators 

   Copyright (C)
     2010,            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_ITER_ADAPTER_STL_H
#define LIB_ITER_ADAPTER_STL_H


#include "lib/iter-adapter.hpp"
#include "lib/iter-adapter-ptr-deref.hpp"

#include <vector>


namespace lib {
namespace iter_stl {
  
  template<typename IT>
  class DistinctIter
    {
    public:
      using value_type = typename IT::value_type;
      using reference  = typename IT::reference;
      using pointer    = typename IT::pointer;
      
    private:
      IT      i_;
      pointer prev_;
      
      void memorise() { if (i_) prev_ = &(*i_); }
      
    public:
      DistinctIter()            : i_(), prev_() { }
      DistinctIter(IT const& i) : i_(i),prev_() { memorise(); }
      
      pointer   operator->()  const { return i_;  }
      reference operator*()   const { return *i_; }
      bool      isValid()     const { return i_;  }
      
      explicit
      operator bool() const
        {
          return bool{i_};
        }
      
      
      DistinctIter&
      operator++()
        {
          do ++i_;
          while (i_ && prev_ && *prev_ == *i_ );
          memorise();
          return *this; 
        }
      
      friend bool operator== (DistinctIter const& i1, DistinctIter const& i2) { return i1.i_ == i2.i_; }
      friend bool operator!= (DistinctIter const& i1, DistinctIter const& i2) { return i1.i_ != i2.i_; }
    };
  
  
  
  template<typename DEF>
  struct WrappedStlIter : DEF
    {
      typedef typename DEF::Iter Iter;
      typedef typename DEF::reference reference;
      typedef typename DEF::pointer  pointer;
      
      
      WrappedStlIter()              : i_()  { }
      WrappedStlIter(Iter const& i) : i_(i) { }
      
      pointer   operator->() const  { return DEF::get(i_);  }
      reference operator*()  const  { return *(DEF::get(i_)); }
      
      WrappedStlIter& operator++()  { ++i_; return *this; }
      
      friend bool operator== (WrappedStlIter const& i1, WrappedStlIter const& i2) { return i1.i_ == i2.i_; }
      friend bool operator!= (WrappedStlIter const& i1, WrappedStlIter const& i2) { return i1.i_ != i2.i_; }
      
    private:
      mutable Iter i_;
    };
  
  
  /* -- customisations for building concrete wrappers -- */
  
  template<typename IT>
  struct Wrapped_Identity
    {
      using Iter = IT;
      using value_type = typename IT::value_type;
      using reference  = typename IT::reference;
      using pointer    = typename IT::pointer;
      
      static Iter get (Iter& it) { return & (*it); }
    };
  
  template<typename IT>
  struct Wrapped_PickKey
    {
      using Iter = IT;
      using value_type = typename IT::value_type::first_type;
      using reference  = value_type &;
      using pointer    = value_type *;
      
      static pointer get (Iter& it) { return & (it->first); }
    };
  
  template<typename IT>
  struct Wrapped_PickVal
    {
      using Iter = IT;
      using value_type = typename IT::value_type::second_type;
      using reference  = value_type &;
      using pointer    = value_type *;
      
      static pointer get (Iter& it) { return & (it->second); }
    };
  
  template<typename IT>
  struct Wrapped_PickConstVal
    {
      using Iter = IT;
      using value_type = const typename IT::value_type::second_type;
      using reference  = const value_type &;
      using pointer    = const value_type *;
      
      static pointer get (Iter& it) { return & (it->second); }
    };
  
  
  
  
  
  
  namespace { // traits and helpers...
    
    template<class MAP>
    struct _MapTypeSelector
      {
        typedef typename MAP::value_type::first_type  Key;
        typedef typename MAP::value_type::second_type Val;
        typedef typename MAP::iterator                Itr;
      };
    
    template<class MAP>
    struct _MapTypeSelector<const MAP>
      {
        typedef typename MAP::value_type::first_type        Key;
        typedef typename MAP::value_type::second_type const Val;
        typedef typename MAP::const_iterator                Itr;
      };
    
    template<class IT, typename SEL>
    struct _MapSubSelector
      {
        typedef WrappedStlIter< Wrapped_PickKey<IT>> PickKey;
        typedef WrappedStlIter< Wrapped_PickVal<IT>> PickVal;
      };
    
    template<class IT, typename SEL>
    struct _MapSubSelector<IT, SEL const&>
      {
        typedef WrappedStlIter< Wrapped_PickKey<IT>>      PickKey; // Key is always const for maps
        typedef WrappedStlIter< Wrapped_PickConstVal<IT>> PickVal;
      };
    
    
    
    template<class MAP>
    struct _MapT
      {
        typedef typename _MapTypeSelector<MAP>::Key KeyType;
        typedef typename _MapTypeSelector<MAP>::Val ValType;
        typedef typename _MapTypeSelector<MAP>::Itr EntryIter;
        
        typedef typename EntryIter::reference DetectConst;
        typedef typename _MapSubSelector<EntryIter,DetectConst>::PickKey PickKeyIter;
        typedef typename _MapSubSelector<EntryIter,DetectConst>::PickVal PickValIter;
        
        typedef RangeIter<PickKeyIter> KeyIter;
        typedef RangeIter<PickValIter> ValIter;
        
        typedef DistinctIter<KeyIter> DistinctKeys;
      };
    
    
    template<class IT>
    struct _MapIterT
      {
        typedef IT EntryIter;
        
        typedef typename EntryIter::value_type::first_type KeyType;
        typedef typename EntryIter::value_type::second_type ValType;
        
        typedef typename EntryIter::reference DetectConst;
        typedef typename _MapSubSelector<EntryIter,DetectConst>::PickKey PickKeyIter;
        typedef typename _MapSubSelector<EntryIter,DetectConst>::PickVal PickValIter;
          
        typedef RangeIter<PickKeyIter> KeyIter;
        typedef RangeIter<PickValIter> ValIter;
        
        typedef DistinctIter<KeyIter> DistinctKeys;
      };
    
    
    
    template<class SEQ>
    struct _SeqT
      {
        typedef typename SEQ::iterator Iter;
        typedef RangeIter<Iter> Range;
        typedef DistinctIter<Range> DistinctVals;
        typedef AddressExposingIter<Range> Addrs;
      };
    
    template<class SEQ>
    struct _SeqT<const SEQ>
      {
        typedef typename SEQ::const_iterator Iter;
        typedef RangeIter<Iter> Range;
        typedef DistinctIter<Range> DistinctVals;
        typedef AddressExposingIter<Range> Addrs;
      };
    
  }//(End) traits/helpers
  
  
  
  
  template<class CON>
  inline typename _SeqT<CON>::Range
  eachElm (CON& coll)
  {
    typedef typename _SeqT<CON>::Range Range;
    return Range (coll.begin(), coll.end());
  }
  
  
  template<class CON>
  inline typename _SeqT<CON>::Addrs
  eachAddress (CON& coll)
  {
    typedef typename _SeqT<CON>::Addrs Addresses;
    return Addresses (eachElm (coll));
  }
  
  
  template<class MAP>
  inline typename _MapT<MAP>::KeyIter
  eachKey (MAP& map)
  {
    typedef typename _MapT<MAP>::KeyIter Range;
    typedef typename _MapT<MAP>::PickKeyIter PickKey;
    
    return Range (PickKey (map.begin()), PickKey (map.end()));
  }
  
  
  template<class IT>
  inline typename _MapIterT<IT>::KeyIter
  eachKey (IT const& begin, IT const& end)
  {
    typedef typename _MapIterT<IT>::KeyIter Range;
    typedef typename _MapIterT<IT>::PickKeyIter PickKey;
    
    return Range (PickKey (begin), PickKey (end));
  }
  
  
  template<class MAP>
  inline typename _MapT<MAP>::ValIter
  eachVal (MAP& map)
  {
    typedef typename _MapT<MAP>::ValIter Range;
    typedef typename _MapT<MAP>::PickValIter PickVal;
    
    return Range (PickVal (map.begin()), PickVal (map.end()));
  }
  
  
  template<class IT>
  inline typename _MapIterT<IT>::ValIter
  eachVal (IT const& begin, IT const& end)
  {
    typedef typename _MapIterT<IT>::ValIter Range;
    typedef typename _MapIterT<IT>::PickValIter PickVal;
    
    return Range (PickVal (begin), PickVal (end));
  }
  
  
  template<class SEQ>
  inline typename _SeqT<SEQ>::DistinctVals
  eachDistinct (SEQ& seq)
  {
    typedef typename _SeqT<SEQ>::Range Range;
    typedef typename _SeqT<SEQ>::DistinctVals DistinctValues;
    
    return DistinctValues (Range (seq.begin(), seq.end()));
  }
  
  
  template<class MAP>
  inline typename _MapT<MAP>::DistinctKeys
  eachDistinctKey (MAP& map)
  {
    return typename _MapT<MAP>::DistinctKeys (eachKey (map));
  }
  
  
  template<class MMAP, typename KEY>
  inline typename _MapT<MMAP>::ValIter
  eachValForKey (MMAP& multimap, KEY key)
  {
    typedef typename _MapT<MMAP>::EntryIter Pos;
    typedef typename _MapT<MMAP>::ValIter Range;
    typedef typename _MapT<MMAP>::PickValIter PickVal;
    
    std::pair<Pos,Pos> valRange = multimap.equal_range (key);
    
    return Range (PickVal (valRange.first), PickVal (valRange.second));
  }
  
  
  
  
  template<typename VAL>
  class IterSnapshot
    {
      typedef std::vector<VAL> Sequence;
      
      mutable
      Sequence buffer_;
      size_t   pos_ = 0;
      
      
    public:
      IterSnapshot() { }
      
      template<class IT>
      IterSnapshot (IT&& src)
        {
          for ( ; src; ++src)
            buffer_.emplace_back (*src);
        }
      
      template<class IT>
      IterSnapshot (IT const& src)
        {
          for (IT copy{src}; copy; ++copy)
            buffer_.emplace_back (*copy);
        }
      
      template<class IT>
      IterSnapshot (IT&& pos, IT const& end)
        {
          for ( ; pos!=end; ++pos)
            buffer_.emplace_back (*pos);
        }
      
      template<class IT>
      IterSnapshot (IT const& begin, IT const& end)
        {
          for (IT pos{begin}; pos!=end; ++pos)
            buffer_.emplace_back (*pos);
        }
      
      IterSnapshot(IterSnapshot &&)                 = default;
      IterSnapshot(IterSnapshot const&)             = default;
      IterSnapshot& operator= (IterSnapshot const&) = default;
      IterSnapshot& operator= (IterSnapshot &&)     = default;
      
      explicit
      operator bool() const
        {
          return isValid();
        }
      
      size_t
      size()  const
        {
          return buffer_.size();
        }
      
      
      
      /* === lumiera forward iterator concept === */
      
      typedef VAL* pointer;
      typedef VAL& reference;
      typedef VAL  value_type;
      
      reference
      operator*() const
        {
          _maybe_throw();
          return buffer_[pos_];
        }
      
      pointer
      operator->() const
        {
          _maybe_throw();
          return &buffer_[pos_];
        }
      
      IterSnapshot&
      operator++()
        {
          _maybe_throw();
          ++pos_;
          return *this;
        }
      
      bool
      isValid ()  const
        {
          return pos_ < buffer_.size();
        }
      
      bool
      empty ()  const
        {
          return not isValid();
        }
      
      ENABLE_USE_IN_STD_RANGE_FOR_LOOPS (IterSnapshot)

      
      
      friend bool
      operator== (IterSnapshot const& s1, IterSnapshot const& s2)
      {
        return (s1.empty()   and  s2.empty())
            or (s1.isValid() and  s2.isValid()
                and s1.pos_    == s2.pos_
                and s1.buffer_ == s2.buffer_
               );
      }
      
      friend bool
      operator!= (IterSnapshot const& snap1, IterSnapshot const& snap2)
      {
        return not (snap1 == snap2);
      }
      
      
    private:
      void
      _maybe_throw()  const
        {
          if (!isValid())
            _throwIterExhausted();
        }
    };
  
  namespace {
    template<class CON>
    using ContentSnapshot = IterSnapshot<typename CON::value_type>;
  }
  
  
  
  template<class CON>
  inline ContentSnapshot<CON>
  snapshot(CON const& con)
  {
    return ContentSnapshot<CON>{begin(con), end(con)};
  }

  template<class IT>
  inline ContentSnapshot<IT>
  dischargeToSnapshot(IT& ii)
  {
    return ContentSnapshot<IT>{ii};
  }
  
  template<class VAL>
  inline iter_stl::IterSnapshot<VAL>
  snapshot(std::initializer_list<VAL> const&& ili)
  {
    using OnceIter = iter_stl::IterSnapshot<VAL>;
    return OnceIter(begin(ili), end(ili));
  }
  
  
}} // namespace lib::iter_stl
#endif