ublas/operation/size.hpp

/**
 * \file size.hpp
 *
 * \brief The family of \c size operations.
 *
 * Copyright (c) 2009-2010, Marco Guazzone
 *
 * Distributed under the Boost Software License, Version 1.0. (See
 * accompanying file LICENSE_1_0.txt or copy at
 * http://www.boost.org/LICENSE_1_0.txt)
 *
 * \author Marco Guazzone, marco.guazzone@gmail.com
 */

#ifndef BOOST_NUMERIC_UBLAS_OPERATION_SIZE_HPP
#define BOOST_NUMERIC_UBLAS_OPERATION_SIZE_HPP


#include <boost/mpl/has_xxx.hpp>
#include <boost/mpl/if.hpp>
#include <boost/numeric/ublas/detail/config.hpp>
#include <boost/numeric/ublas/expression_types.hpp>
#include <boost/numeric/ublas/fwd.hpp>
#include <boost/numeric/ublas/tags.hpp>
#include <boost/numeric/ublas/traits.hpp>
#include <boost/utility/enable_if.hpp>
#include <cstddef>


namespace boost { namespace numeric { namespace ublas {

namespace detail { namespace /*<unnamed>*/ {

/// Define a \c has_size_type trait class.
BOOST_MPL_HAS_XXX_TRAIT_DEF(size_type)


/**
 * \brief Wrapper type-traits used in \c boost::lazy_enabled_if for getting the
 *  size type (see below).
 * \tparam VectorT A vector type.
 */
template <typename VectorT>
struct vector_size_type
{
    /// The size type.
    typedef typename vector_traits<VectorT>::size_type type;
};

/**
 * \brief Wrapper type-traits used in \c boost::lazy_enabled_if for getting the
 *  size type (see below).
 * \tparam MatrixT A matrix type.
 */
template <typename MatrixT>
struct matrix_size_type
{
    /// The size type.
    typedef typename matrix_traits<MatrixT>::size_type type;
};


/**
 * \brief Auxiliary class for computing the size of the given dimension for
 *  a container of the given category.
 * \tparam Dim The dimension number (starting from 1).
 * \tparam CategoryT The category type (e.g., vector_tag).
 */
template <std::size_t Dim, typename CategoryT>
struct size_by_dim_impl;


/**
 * \brief Auxiliary class for computing the size of the given dimension for
 *  a container of the given category and with the given orientation.
 * \tparam Dim The dimension number (starting from 1).
 * \tparam CategoryT The category type (e.g., vector_tag).
 * \tparam OrientationT The orientation category type (e.g., row_major_tag).
 */
template <typename TagT, typename CategoryT, typename OrientationT>
struct size_by_tag_impl;


/**
 * \brief Specialization of \c size_by_dim_impl for computing the size of a
 *  vector.
 */
template <>
struct size_by_dim_impl<1, vector_tag>
{
    /**
     * \brief Compute the size of the given vector.
     * \tparam ExprT A vector expression type.
     * \pre ExprT must be a model of VectorExpression.
     */
    template <typename ExprT>
    BOOST_UBLAS_INLINE
    static typename vector_traits<ExprT>::size_type apply(vector_expression<ExprT> const& ve)
    {
        return ve().size();
    }
};


/**
 * \brief Specialization of \c size_by_dim_impl for computing the number of
 *  rows of a matrix
 */
template <>
struct size_by_dim_impl<1, matrix_tag>
{
    /**
     * \brief Compute the number of rows of the given matrix.
     * \tparam ExprT A matrix expression type.
     * \pre ExprT must be a model of MatrixExpression.
     */
    template <typename ExprT>
    BOOST_UBLAS_INLINE
    static typename matrix_traits<ExprT>::size_type apply(matrix_expression<ExprT> const& me)
    {
        return me().size1();
    }
};


/**
 * \brief Specialization of \c size_by_dim_impl for computing the number of
 *  columns of a matrix
 */
template <>
struct size_by_dim_impl<2, matrix_tag>
{
    /**
     * \brief Compute the number of columns of the given matrix.
     * \tparam ExprT A matrix expression type.
     * \pre ExprT must be a model of MatrixExpression.
     */
    template <typename ExprT>
    BOOST_UBLAS_INLINE
    static typename matrix_traits<ExprT>::size_type apply(matrix_expression<ExprT> const& me)
    {
        return me().size2();
    }
};


/**
 * \brief Specialization of \c size_by_tag_impl for computing the size of the
 *  major dimension of a row-major oriented matrix.
 */
template <>
struct size_by_tag_impl<tag::major, matrix_tag, row_major_tag>
{
    /**
     * \brief Compute the number of rows of the given matrix.
     * \tparam ExprT A matrix expression type.
     * \pre ExprT must be a model of MatrixExpression.
     */
    template <typename ExprT>
    BOOST_UBLAS_INLINE
    static typename matrix_traits<ExprT>::size_type apply(matrix_expression<ExprT> const& me)
    {
        return me().size1();
    }
};


/**
 * \brief Specialization of \c size_by_tag_impl for computing the size of the
 *  minor dimension of a row-major oriented matrix.
 */
template <>
struct size_by_tag_impl<tag::minor, matrix_tag, row_major_tag>
{
    /**
     * \brief Compute the number of columns of the given matrix.
     * \tparam ExprT A matrix expression type.
     * \pre ExprT must be a model of MatrixExpression.
     */
    template <typename ExprT>
    BOOST_UBLAS_INLINE
    static typename matrix_traits<ExprT>::size_type apply(matrix_expression<ExprT> const& me)
    {
        return me().size2();
    }
};


/**
 * \brief Specialization of \c size_by_tag_impl for computing the size of the
 *  leading dimension of a row-major oriented matrix.
 */
template <>
struct size_by_tag_impl<tag::leading, matrix_tag, row_major_tag>
{
    /**
     * \brief Compute the number of columns of the given matrix.
     * \tparam ExprT A matrix expression type.
     * \pre ExprT must be a model of MatrixExpression.
     */
    template <typename ExprT>
    BOOST_UBLAS_INLINE
    static typename matrix_traits<ExprT>::size_type apply(matrix_expression<ExprT> const& me)
    {
        return me().size2();
    }
};


/// \brief Specialization of \c size_by_tag_impl for computing the size of the
///  major dimension of a column-major oriented matrix.
template <>
struct size_by_tag_impl<tag::major, matrix_tag, column_major_tag>
{
    /**
     * \brief Compute the number of columns of the given matrix.
     * \tparam ExprT A matrix expression type.
     * \pre ExprT must be a model of MatrixExpression.
     */
    template <typename ExprT>
    BOOST_UBLAS_INLINE
    static typename matrix_traits<ExprT>::size_type apply(matrix_expression<ExprT> const& me)
    {
        return me().size2();
    }
};


/// \brief Specialization of \c size_by_tag_impl for computing the size of the
///  minor dimension of a column-major oriented matrix.
template <>
struct size_by_tag_impl<tag::minor, matrix_tag, column_major_tag>
{
    /**
     * \brief Compute the number of rows of the given matrix.
     * \tparam ExprT A matrix expression type.
     * \pre ExprT must be a model of MatrixExpression.
     */
    template <typename ExprT>
    BOOST_UBLAS_INLINE
    static typename matrix_traits<ExprT>::size_type apply(matrix_expression<ExprT> const& me)
    {
        return me().size1();
    }
};


/// \brief Specialization of \c size_by_tag_impl for computing the size of the
///  leading dimension of a column-major oriented matrix.
template <>
struct size_by_tag_impl<tag::leading, matrix_tag, column_major_tag>
{
    /**
     * \brief Compute the number of rows of the given matrix.
     * \tparam ExprT A matrix expression type.
     * \pre ExprT must be a model of MatrixExpression.
     */
    template <typename ExprT>
    BOOST_UBLAS_INLINE
    static typename matrix_traits<ExprT>::size_type apply(matrix_expression<ExprT> const& me)
    {
        return me().size1();
    }
};


/// \brief Specialization of \c size_by_tag_impl for computing the size of the
///  given dimension of a unknown oriented expression.
template <typename TagT, typename CategoryT>
struct size_by_tag_impl<TagT, CategoryT, unknown_orientation_tag>: size_by_tag_impl<TagT, CategoryT, row_major_tag>
{
    // Empty
};

}} // Namespace detail::<unnamed>


/**
 * \brief Return the number of columns.
 * \tparam VectorExprT A type which models the vector expression concept.
 * \param ve A vector expression.
 * \return The length of the input vector expression.
 */
template <typename VectorExprT>
BOOST_UBLAS_INLINE
typename ::boost::lazy_enable_if_c<
    detail::has_size_type<VectorExprT>::value,
    detail::vector_size_type<VectorExprT>
>::type size(vector_expression<VectorExprT> const& ve)
{
    return ve().size();
}


/**
 * \brief Return the size of the given dimension for the given vector
 *  expression.
 * \tparam Dim The dimension number (starting from 1).
 * \tparam VectorExprT A vector expression type.
 * \param ve A vector expression.
 * \return The length of the input vector expression.
 */
template <std::size_t Dim, typename VectorExprT>
BOOST_UBLAS_INLINE
typename vector_traits<VectorExprT>::size_type size(vector_expression<VectorExprT> const& ve)
{
    return detail::size_by_dim_impl<Dim, vector_tag>::template apply(ve);
}


/**
 * \brief Return the size of the given dimension for the given matrix
 *  expression.
 * \tparam Dim The dimension number (starting from 1).
 * \tparam MatrixExprT A matrix expression type.
 * \param e A matrix expression.
 * \return The size of the input matrix expression associated to the dimension
 *  \a Dim.
 */
template <std::size_t Dim, typename MatrixExprT>
BOOST_UBLAS_INLINE
typename matrix_traits<MatrixExprT>::size_type size(matrix_expression<MatrixExprT> const& me)
{
    return detail::size_by_dim_impl<Dim, matrix_tag>::template apply(me);
}


/**
 * \brief Return the size of the given dimension tag for the given matrix
 *  expression.
 * \tparam TagT The dimension tag type (e.g., tag::major).
 * \tparam MatrixExprT A matrix expression type.
 * \param e A matrix expression.
 * \return The size of the input matrix expression associated to the dimension
 *  tag \a TagT.
 */
template <typename TagT, typename MatrixExprT>
BOOST_UBLAS_INLINE
typename ::boost::lazy_enable_if_c<
    detail::has_size_type<MatrixExprT>::value,
    detail::matrix_size_type<MatrixExprT>
>::type size(matrix_expression<MatrixExprT> const& me)
{
    return detail::size_by_tag_impl<TagT, matrix_tag, typename matrix_traits<MatrixExprT>::orientation_category>::template apply(me);
}

}}} // Namespace boost::numeric::ublas


#endif // BOOST_NUMERIC_UBLAS_OPERATION_SIZE_HPP