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// -*- c++ -*-
/*
* Copyright (c) 2010-2012, Jim Bosch
* All rights reserved.
*
* ndarray is distributed under a simple BSD-like license;
* see the LICENSE file that should be present in the root
* of the source distribution, or alternately available at:
* https://github.com/ndarray/ndarray
*/
#ifndef NDARRAY_ExpressionBase_h_INCLUDED
#define NDARRAY_ExpressionBase_h_INCLUDED
/**
* @file ndarray/ExpressionBase.h
*
* @brief Definitions for ExpressionBase.
*/
#include "ndarray/ExpressionTraits.h"
#include "ndarray/Vector.h"
namespace ndarray {
/**
* @class ExpressionBase
* @brief CRTP base class for all multidimensional expressions.
*
* @ingroup MainGroup
*
* ExpressionBase is a CRTP base class for both true array objects (subclasses of
* ArrayBase) and lazy array expressions, which are created by most arithmetic,
* bitwise, and logical operations on arrays. These lazy expressions have most
* of the features of a true array to a const data type.
*
* ExpressionBase also provides implementations for a few STL compatibility and
* convenience member functions.
*/
template <typename Derived>
class ExpressionBase {
public:
/// @brief Data type of expression elements.
typedef typename ExpressionTraits<Derived>::Element Element;
/// @brief Number of dimensions (boost::mpl::int_).
typedef typename ExpressionTraits<Derived>::ND ND;
/// @brief Nested expression or element iterator.
typedef typename ExpressionTraits<Derived>::Iterator Iterator;
/// @brief Nested expression or element reference.
typedef typename ExpressionTraits<Derived>::Reference Reference;
/// @brief Nested expression or element value type.
typedef typename ExpressionTraits<Derived>::Value Value;
/// @brief Vector type for N-dimensional indices.
typedef Vector<Size,ND::value> Index;
/// @brief CRTP derived type.
typedef Derived Self;
/// @brief Return a single nested expression or element.
Reference operator[](Size n) const { return getSelf().operator[](n); }
/// @brief Return the first nested expression or element.
Reference front() const { return this->operator[](0); }
/// @brief Return the last nested expression or element.
Reference back() const { return this->operator[](this->template getSize<0>()-1); }
/// @brief Return an Iterator to the beginning of the expression.
Iterator begin() const { return getSelf().begin(); }
/// @brief Return an Iterator to one past the end of the expression.
Iterator end() const { return getSelf().end(); }
/// @brief Return the size of a specific dimension.
template <int P> Size getSize() const { return getSelf().template getSize<P>(); }
/// @brief Return a Vector of the sizes of all dimensions.
Index getShape() const { return getSelf().getShape(); }
/// @brief Return the total number of elements in the expression.
Size getNumElements() const { return getSelf().getNumElements(); }
/* ------------------------- STL Compatibility -------------------------- */
typedef Value value_type;
typedef Iterator iterator;
typedef Iterator const_iterator;
typedef Reference reference;
typedef Reference const_reference;
typedef Iterator pointer;
typedef Offset difference_type;
typedef Size size_type;
/// @brief Return the size of the first dimension.
size_type size() const { return this->template getSize<0>(); }
/// @brief Return true if the first dimension has no elements.
bool empty() const { return this->template getSize<0>() == 0; }
/* ---------------------------------------------------------------------- */
protected:
Self & getSelf() { return *static_cast<Self *>(this); }
Self const & getSelf() const { return *static_cast<Self const *>(this); }
};
} // namespace ndarray
#endif // !NDARRAY_ExpressionBase_h_INCLUDED