Lib/python/pyiterators.swg

/* -----------------------------------------------------------------------------
 * pyiterators.swg
 *
 * Implement a python 'output' iterator.
 *
 * Users can derive form the SwigPyIterator to implement their
 * own iterators. As an example (real one since we use it for STL/STD
 * containers), the template SwigPyIterator_T does the
 * implementation for generic C++ iterators.
 *
 * The concept here is for a 'closed' iterator to implement a true Python
 * iterator which raises a StopIteration at the end of an iteration over a range.
 * An 'open' iterator is more like a traditional C++ iterator and does not
 * raise a StopIteration.
 * ----------------------------------------------------------------------------- */

%include <std_common.i>

%fragment("SwigPyIterator","header",fragment="<stddef.h>") {
namespace swig {
  struct SwigPyIterator {
  private:
    SwigPtr_PyObject _seq;

  protected:
    SwigPyIterator(PyObject *seq) : _seq(seq)
    {
    }

    void raise_stop_iteration() const
    {
      SWIG_SetErrorObj(PyExc_StopIteration, SWIG_Py_Void());
    }

  public:
    virtual ~SwigPyIterator() {}

    // Access iterator method, required by Python
    virtual PyObject *value() const = 0;

    // Forward iterator method, required by Python
    virtual SwigPyIterator *incr(size_t n = 1) = 0;
    
    // Backward iterator method, very common in C++, but not required in Python
    // This default probably ought to instead raise some sort of unsupported exception
    virtual SwigPyIterator *decr(size_t /*n*/ = 1)
    {
      raise_stop_iteration();
      return NULL;
    }

    // Random access iterator methods, but not required in Python
    virtual ptrdiff_t distance(const SwigPyIterator &/*x*/) const
    {
      throw std::invalid_argument("operation not supported");
    }

    virtual bool equal (const SwigPyIterator &/*x*/) const
    {
      throw std::invalid_argument("operation not supported");
    }
    
    // C++ common/needed methods
    virtual SwigPyIterator *copy() const = 0;

    PyObject *__next__()
    {
      SWIG_PYTHON_THREAD_BEGIN_BLOCK; // disable threads       
      PyObject *obj = value();
      if (obj)
        if (!incr())
          obj = NULL;
      SWIG_PYTHON_THREAD_END_BLOCK; // re-enable threads
      return obj;     
    }

    PyObject *previous()
    {
      SWIG_PYTHON_THREAD_BEGIN_BLOCK; // disable threads       
      if (!decr())
        return NULL;
      PyObject *obj = value();
      SWIG_PYTHON_THREAD_END_BLOCK; // re-enable threads       
      return obj;
    }

    SwigPyIterator *advance(ptrdiff_t n)
    {
      return  (n > 0) ?  incr((size_t)n) : decr((size_t)(-n));
    }
      
    bool operator == (const SwigPyIterator& x)  const
    {
      return equal(x);
    }
      
    bool operator != (const SwigPyIterator& x) const
    {
      return ! operator==(x);
    }
      
    SwigPyIterator& operator += (ptrdiff_t n)
    {
      SwigPyIterator *ret = advance(n);
      return ret ? *ret : *this;
    }

    SwigPyIterator& operator -= (ptrdiff_t n)
    {
      SwigPyIterator *ret = advance(-n);
      return ret ? *ret : *this;
    }
      
    SwigPyIterator* operator + (ptrdiff_t n) const
    {
      return copy()->advance(n);
    }

    SwigPyIterator* operator - (ptrdiff_t n) const
    {
      return copy()->advance(-n);
    }
      
    ptrdiff_t operator - (const SwigPyIterator& x) const
    {
      return x.distance(*this);
    }
      
    static swig_type_info* descriptor() {
      static swig_type_info* desc = SWIG_TypeQuery("swig::" SWIG_STRINGIFY(SwigPyIterator) " *");
      return desc;
    }
  };

%#if defined(SWIGPYTHON_BUILTIN)
  inline PyObject* make_output_iterator_builtin (PyObject *pyself)
  {
    SWIG_Py_INCREF(pyself);
    return pyself;
  }
%#endif
}
}

%fragment("SwigPyIterator_T","header",fragment="<stddef.h>",fragment="SwigPyIterator",fragment="StdTraits",fragment="StdIteratorTraits") {
namespace swig {
  template<typename OutIterator>
  class SwigPyIterator_T :  public SwigPyIterator
  {
  public:
    typedef OutIterator out_iterator;
    typedef typename std::iterator_traits<out_iterator>::value_type value_type;    
    typedef SwigPyIterator_T<out_iterator> self_type;

    SwigPyIterator_T(out_iterator curr, PyObject *seq)
      : SwigPyIterator(seq), current(curr)
    {
    }

    const out_iterator& get_current() const
    {
      return current;
    }

    
    bool equal (const SwigPyIterator &iter) const SWIG_OVERRIDE
    {
      const self_type *iters = dynamic_cast<const self_type *>(&iter);
      if (iters) {
	return (current == iters->get_current());
      } else {
	throw std::invalid_argument("bad iterator type");
      }
    }
    
    ptrdiff_t distance(const SwigPyIterator &iter) const SWIG_OVERRIDE
    {
      const self_type *iters = dynamic_cast<const self_type *>(&iter);
      if (iters) {
	return std::distance(current, iters->get_current());
      } else {
	throw std::invalid_argument("bad iterator type");
      }
    }    
    
  protected:
    out_iterator current;
  };
  
  template <class ValueType>
  struct from_oper 
  {
    typedef const ValueType& argument_type;
    typedef PyObject *result_type;
    result_type operator()(argument_type v) const
    {
      return swig::from(v);
    }
  };

  template<typename OutIterator, 
	   typename ValueType = typename std::iterator_traits<OutIterator>::value_type,
	   typename FromOper = from_oper<ValueType> >
  class SwigPyForwardIteratorOpen_T :  public SwigPyIterator_T<OutIterator>
  {
  public:
    FromOper from;
    typedef OutIterator out_iterator;
    typedef ValueType value_type;
    typedef SwigPyIterator_T<out_iterator>  base;
    typedef SwigPyForwardIteratorOpen_T<OutIterator, ValueType, FromOper> self_type;
    
    SwigPyForwardIteratorOpen_T(out_iterator curr, PyObject *seq)
      : SwigPyIterator_T<OutIterator>(curr, seq)
    {
    }
    
    PyObject *value() const SWIG_OVERRIDE {
      return from(static_cast<const value_type&>(*(base::current)));
    }
    
    SwigPyIterator *copy() const SWIG_OVERRIDE
    {
      return new self_type(*this);
    }

    SwigPyIterator *incr(size_t n = 1) SWIG_OVERRIDE
    {
      // Open iterator does not raise StopIteration
      while (n--) {
	++base::current;
      }
      return this;
    }

  };

  template<typename OutIterator, 
	   typename ValueType = typename std::iterator_traits<OutIterator>::value_type,
	   typename FromOper = from_oper<ValueType> >
  class SwigPyIteratorOpen_T :  public SwigPyForwardIteratorOpen_T<OutIterator, ValueType, FromOper>
  {
  public:
    FromOper from;
    typedef OutIterator out_iterator;
    typedef ValueType value_type;
    typedef SwigPyIterator_T<out_iterator>  base;
    typedef SwigPyIteratorOpen_T<OutIterator, ValueType, FromOper> self_type;
    
    SwigPyIteratorOpen_T(out_iterator curr, PyObject *seq)
      : SwigPyForwardIteratorOpen_T<OutIterator>(curr, seq)
    {
    }

    SwigPyIterator *decr(size_t n = 1) SWIG_OVERRIDE
    {
      // Open iterator does not raise StopIteration
      while (n--) {
	--base::current;
      }
      return this;
    }
  };

  template<typename OutIterator, 
	   typename ValueType = typename std::iterator_traits<OutIterator>::value_type,
	   typename FromOper = from_oper<ValueType> >
  class SwigPyForwardIteratorClosed_T :  public SwigPyIterator_T<OutIterator>
  {
  public:
    FromOper from;
    typedef OutIterator out_iterator;
    typedef ValueType value_type;
    typedef SwigPyIterator_T<out_iterator>  base;    
    typedef SwigPyForwardIteratorClosed_T<OutIterator, ValueType, FromOper> self_type;
    
    SwigPyForwardIteratorClosed_T(out_iterator curr, out_iterator first, out_iterator last, PyObject *seq)
      : SwigPyIterator_T<OutIterator>(curr, seq), begin(first), end(last)
    {
    }
    
    PyObject *value() const SWIG_OVERRIDE {
      if (base::current == end) {
	base::raise_stop_iteration();
	return NULL;
      } else {
	return from(static_cast<const value_type&>(*(base::current)));
      }
    }
    
    SwigPyIterator *copy() const SWIG_OVERRIDE
    {
      return new self_type(*this);
    }

    SwigPyIterator *incr(size_t n = 1) SWIG_OVERRIDE
    {
      while (n--) {
	if (base::current == end) {
	  base::raise_stop_iteration();
	  return NULL;
	} else {
	  ++base::current;
	}
      }
      return this;
    }

  protected:
    out_iterator begin;
    out_iterator end;
  };

  template<typename OutIterator, 
	   typename ValueType = typename std::iterator_traits<OutIterator>::value_type,
	   typename FromOper = from_oper<ValueType> >
  class SwigPyIteratorClosed_T :  public SwigPyForwardIteratorClosed_T<OutIterator,ValueType,FromOper>
  {
  public:
    FromOper from;
    typedef OutIterator out_iterator;
    typedef ValueType value_type;
    typedef SwigPyIterator_T<out_iterator>  base;
    typedef SwigPyForwardIteratorClosed_T<OutIterator, ValueType, FromOper> base0;
    typedef SwigPyIteratorClosed_T<OutIterator, ValueType, FromOper> self_type;
    
    SwigPyIteratorClosed_T(out_iterator curr, out_iterator first, out_iterator last, PyObject *seq)
      : SwigPyForwardIteratorClosed_T<OutIterator,ValueType,FromOper>(curr, first, last, seq)
    {
    }

    SwigPyIterator *decr(size_t n = 1) SWIG_OVERRIDE
    {
      while (n--) {
	if (base::current == base0::begin) {
	  base0::raise_stop_iteration();
	  return NULL;
	} else {
	  --base::current;
	}
      }
      return this;
    }
  };


  template<typename OutIter>
  inline SwigPyIterator*
  make_output_forward_iterator(const OutIter& current, const OutIter& begin,const OutIter& end, PyObject *seq = 0)
  {
    return new SwigPyForwardIteratorClosed_T<OutIter>(current, begin, end, seq);
  }

  template<typename OutIter>
  inline SwigPyIterator*
  make_output_iterator(const OutIter& current, const OutIter& begin,const OutIter& end, PyObject *seq = 0)
  {
    return new SwigPyIteratorClosed_T<OutIter>(current, begin, end, seq);
  }

  template<typename OutIter>
  inline SwigPyIterator*
  make_output_forward_iterator(const OutIter& current, PyObject *seq = 0)
  {
    return new SwigPyForwardIteratorOpen_T<OutIter>(current, seq);
  }

  template<typename OutIter>
  inline SwigPyIterator*
  make_output_iterator(const OutIter& current, PyObject *seq = 0)
  {
    return new SwigPyIteratorOpen_T<OutIter>(current, seq);
  }

}
}


%fragment("SwigPyIterator");
namespace swig 
{
%typemap(out, noblock=1) SwigPyIterator * {
  if (!$1) SWIG_fail;
  $result = SWIG_NewPointerObj(SWIG_as_voidptr($1), $descriptor, $owner);
}

%typemap(out, noblock=1) SwigPyIterator & {
  if (PyErr_Occurred()) SWIG_fail;
  $result = SWIG_NewPointerObj(SWIG_as_voidptr($1), $descriptor, $owner);
}

  /* 
     Mark methods that return new objects
  */
  %newobject SwigPyIterator::copy;
  %newobject SwigPyIterator::operator + (ptrdiff_t n) const;
  %newobject SwigPyIterator::operator - (ptrdiff_t n) const;

  %nodirector SwigPyIterator;

#if defined(SWIGPYTHON_BUILTIN)
  %feature("python:tp_iter") SwigPyIterator "&swig::make_output_iterator_builtin";
  %feature("python:slot", "tp_iternext", functype="iternextfunc") SwigPyIterator::__next__;
#else
  %extend SwigPyIterator {
  %pythoncode %{def __iter__(self):
    return self%}
  }
#endif

  %catches(std::invalid_argument) SwigPyIterator::distance(const SwigPyIterator &x) const;
  %catches(std::invalid_argument) SwigPyIterator::equal (const SwigPyIterator &x) const;

  struct SwigPyIterator
  {
  protected:
    SwigPyIterator(PyObject *seq);
    void raise_stop_iteration();

  public:
    virtual ~SwigPyIterator();

    // Access iterator method, required by Python
    virtual PyObject *value() const = 0;

    // Forward iterator method, required by Python
    virtual SwigPyIterator *incr(size_t n = 1) = 0;
    
    // Backward iterator method, very common in C++, but not required in Python
    virtual SwigPyIterator *decr(size_t n = 1);

    // Random access iterator methods, but not required in Python
    virtual ptrdiff_t distance(const SwigPyIterator &x) const;

    virtual bool equal (const SwigPyIterator &x) const;
    
    // C++ common/needed methods
    virtual SwigPyIterator *copy() const = 0;

    PyObject *__next__();
    PyObject *previous();
    SwigPyIterator *advance(ptrdiff_t n);

    bool operator == (const SwigPyIterator& x)  const;
    bool operator != (const SwigPyIterator& x) const;
    SwigPyIterator& operator += (ptrdiff_t n);
    SwigPyIterator& operator -= (ptrdiff_t n);
    SwigPyIterator* operator + (ptrdiff_t n) const;
    SwigPyIterator* operator - (ptrdiff_t n) const;
    ptrdiff_t operator - (const SwigPyIterator& x) const;
  };
}