diff options
Diffstat (limited to 'include/2geom/symbolic/multi-index.h')
| -rw-r--r-- | include/2geom/symbolic/multi-index.h | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/include/2geom/symbolic/multi-index.h b/include/2geom/symbolic/multi-index.h new file mode 100644 index 0000000..311fae8 --- /dev/null +++ b/include/2geom/symbolic/multi-index.h @@ -0,0 +1,169 @@ +/* + * A multi-index is an ordered sequence of unsigned int + * + * Authors: + * Marco Cecchetti <mrcekets at gmail.com> + * + * Copyright 2008 authors + * + * This library is free software; you can redistribute it and/or + * modify it either under the terms of the GNU Lesser General Public + * License version 2.1 as published by the Free Software Foundation + * (the "LGPL") or, at your option, under the terms of the Mozilla + * Public License Version 1.1 (the "MPL"). If you do not alter this + * notice, a recipient may use your version of this file under either + * the MPL or the LGPL. + * + * You should have received a copy of the LGPL along with this library + * in the file COPYING-LGPL-2.1; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * You should have received a copy of the MPL along with this library + * in the file COPYING-MPL-1.1 + * + * The contents of this file are subject to the Mozilla Public License + * Version 1.1 (the "License"); you may not use this file except in + * compliance with the License. You may obtain a copy of the License at + * http://www.mozilla.org/MPL/ + * + * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY + * OF ANY KIND, either express or implied. See the LGPL or the MPL for + * the specific language governing rights and limitations. + */ + +#ifndef _GEOM_SL_MULTI_INDEX_H_ +#define _GEOM_SL_MULTI_INDEX_H_ + + +#include <2geom/exception.h> + +#include <valarray> + +#include <boost/preprocessor/cat.hpp> +#include <boost/preprocessor/repetition/enum_params.hpp> +#include <boost/preprocessor/repetition/repeat.hpp> +#include <boost/preprocessor/repetition/repeat_from_to.hpp> + + + + +/* + * an helper macro for generating function with declaration: + * multi_index_type make_multi_index (size_t i0, ..., size_t iN) + * that is a facility to make up a multi-index from a list of values + */ + +#define GEOM_SL_MAX_RANK 10 + +#define GEOM_SL_ASSIGN_INDEX(z, k, unused) I[k] = BOOST_PP_CAT(i, k); + +#define GEOM_SL_MAKE_MULTI_INDEX(z, N, unused) \ +inline \ +multi_index_type make_multi_index (BOOST_PP_ENUM_PARAMS(N, size_t i)) \ +{ \ + multi_index_type I(N); \ + BOOST_PP_REPEAT(N, GEOM_SL_ASSIGN_INDEX, unused) \ + return I; \ +} +// end macro GEOM_SL_MAKE_MULTI_INDEX + + + + +namespace Geom { namespace SL { + +/* + * A multi-index is an ordered sequence of unsigned int; + * it's useful for representing exponent, degree and coefficient index + * of a multi-variate polynomial; + * example: given a monomial x_(0)^i_(0)*x_(1)^i_(1)*...*x_(N-1)^i_(N-1) + * we can write it in the simpler form X^I where X=(x_(0), .., x_(N-1)) + * and I=(i_(0), .., i_(N-1)) is a multi-index + * A multi-index is represented as a valarray this let us make simple + * arithmetic operations on a multi-index + */ + +typedef std::valarray<size_t> multi_index_type; + + +// make up a multi-index of size N and fill it with zeroes +inline +multi_index_type multi_index_zero(size_t N) +{ + return multi_index_type(N); +} + +// helper functions for generating a multi-index from a list of values +// we create an amount of GEOM_SL_MAX_RANK of suzh functions +BOOST_PP_REPEAT_FROM_TO(0, GEOM_SL_MAX_RANK, GEOM_SL_MAKE_MULTI_INDEX, unused) + + +// helper function for generating a multi-index of size N +// from a single index v that is placed at position i with i in [0,N[ +template <size_t N> +inline +multi_index_type make_multi_index(size_t i, size_t v) +{ + if (!(i < N)) + THROW_RANGEERROR ("make_multi_index<N> from a single index: " + "out of range position"); + multi_index_type I(N); + I[i] = v; + return I; +} + +// transform a N size multi-index in (N-1)-size multi-index +// by removing the first index: (i1, i2,...,iN) -> (i2,..,iN) +inline +multi_index_type shift(multi_index_type const& I, size_t i = 1) +{ + size_t N = I.size() - i; + multi_index_type J = I[std::slice(i, N, 1)]; + return J; +} + +// valarray operator== returns a valarray of bool +inline +bool is_equal(multi_index_type const& I, multi_index_type const& J) +{ + if (I.size() != J.size()) return false; + for (size_t i = 0; i < I.size(); ++i) + if (I[i] != J[i]) return false; + return true; +} + +// extended operator<< for printing a multi-index +template <typename charT> +inline +std::basic_ostream<charT> & +operator<< (std::basic_ostream<charT> & os, + const Geom::SL::multi_index_type & I) +{ + if (I.size() == 0 ) return os; + os << "[" << I[0]; + for (unsigned int i = 1; i < I.size(); ++i) + { + os << ", " << I[i]; + } + os << "]"; + return os; +} + +} /*end namespace Geom*/ } /*end namespace SL*/ + +// argument dependent name lookup doesn't work with typedef +using Geom::SL::operator<<; + + +#endif // _GEOM_SL_MULTI_INDEX_ + + +/* + Local Variables: + mode:c++ + c-file-style:"stroustrup" + c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +)) + indent-tabs-mode:nil + fill-column:99 + End: +*/ +// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 : |