361 lines
14 KiB
Plaintext
361 lines
14 KiB
Plaintext
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// Copyright Neil Groves 2009. Use, modification and
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// distribution is subject to the Boost Software License, Version
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// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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//
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// For more information, see http://www.boost.org/libs/range/
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//
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#ifndef BOOST_RANGE_ALGORITHM_SEARCH_N_HPP_INCLUDED
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#define BOOST_RANGE_ALGORITHM_SEARCH_N_HPP_INCLUDED
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#include <boost/concept_check.hpp>
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#include <boost/range/begin.hpp>
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#include <boost/range/end.hpp>
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#include <boost/range/concepts.hpp>
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#include <boost/range/detail/range_return.hpp>
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#include <boost/range/value_type.hpp>
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#include <iterator>
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#include <algorithm>
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namespace boost
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{
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namespace range_detail
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{
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// Rationale: search_n is implemented rather than delegate to
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// the standard library implementation because some standard
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// library implementations are broken eg. MSVC.
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// search_n forward iterator version
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template<typename ForwardIterator, typename Integer, typename Value>
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inline ForwardIterator
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search_n_impl(ForwardIterator first, ForwardIterator last, Integer count,
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const Value& value, std::forward_iterator_tag)
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{
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first = std::find(first, last, value);
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while (first != last)
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{
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typename std::iterator_traits<ForwardIterator>::difference_type n = count;
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ForwardIterator i = first;
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++i;
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while (i != last && n != 1 && *i==value)
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{
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++i;
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--n;
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}
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if (n == 1)
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return first;
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if (i == last)
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return last;
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first = std::find(++i, last, value);
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}
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return last;
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}
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// search_n random-access iterator version
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template<typename RandomAccessIterator, typename Integer, typename Value>
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inline RandomAccessIterator
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search_n_impl(RandomAccessIterator first, RandomAccessIterator last,
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Integer count, const Value& value,
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std::random_access_iterator_tag)
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{
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typedef typename std::iterator_traits<RandomAccessIterator>::difference_type difference_t;
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difference_t tail_size = last - first;
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const difference_t pattern_size = count;
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if (tail_size < pattern_size)
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return last;
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const difference_t skip_offset = pattern_size - 1;
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RandomAccessIterator look_ahead = first + skip_offset;
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tail_size -= pattern_size;
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while (1)
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{
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// look_ahead here is pointing to the last element of the
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// next possible match
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while (!(*look_ahead == value)) // skip loop...
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{
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if (tail_size < pattern_size)
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return last; // no match
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look_ahead += pattern_size;
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tail_size -= pattern_size;
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}
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difference_t remainder = skip_offset;
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for (RandomAccessIterator back_track = look_ahead - 1;
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*back_track == value; --back_track)
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{
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if (--remainder == 0)
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{
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return look_ahead - skip_offset; // matched
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}
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}
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if (remainder > tail_size)
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return last; // no match
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look_ahead += remainder;
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tail_size -= remainder;
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}
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return last;
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}
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// search_n for forward iterators using a binary predicate
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// to determine a match
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template<typename ForwardIterator, typename Integer, typename Value,
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typename BinaryPredicate>
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inline ForwardIterator
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search_n_pred_impl(ForwardIterator first, ForwardIterator last,
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Integer count, const Value& value,
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BinaryPredicate pred, std::forward_iterator_tag)
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{
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typedef typename std::iterator_traits<ForwardIterator>::difference_type difference_t;
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while (first != last && !static_cast<bool>(pred(*first, value)))
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++first;
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while (first != last)
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{
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difference_t n = count;
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ForwardIterator i = first;
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++i;
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while (i != last && n != 1 && static_cast<bool>(pred(*i, value)))
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{
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++i;
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--n;
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}
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if (n == 1)
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return first;
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if (i == last)
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return last;
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first = ++i;
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while (first != last && !static_cast<bool>(pred(*first, value)))
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++first;
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}
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return last;
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}
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// search_n for random-access iterators using a binary predicate
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// to determine a match
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template<typename RandomAccessIterator, typename Integer,
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typename Value, typename BinaryPredicate>
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inline RandomAccessIterator
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search_n_pred_impl(RandomAccessIterator first, RandomAccessIterator last,
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Integer count, const Value& value,
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BinaryPredicate pred, std::random_access_iterator_tag)
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{
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typedef typename std::iterator_traits<RandomAccessIterator>::difference_type difference_t;
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difference_t tail_size = last - first;
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const difference_t pattern_size = count;
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if (tail_size < pattern_size)
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return last;
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const difference_t skip_offset = pattern_size - 1;
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RandomAccessIterator look_ahead = first + skip_offset;
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tail_size -= pattern_size;
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while (1)
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{
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// look_ahead points to the last element of the next
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// possible match
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while (!static_cast<bool>(pred(*look_ahead, value))) // skip loop
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{
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if (tail_size < pattern_size)
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return last; // no match
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look_ahead += pattern_size;
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tail_size -= pattern_size;
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}
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difference_t remainder = skip_offset;
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for (RandomAccessIterator back_track = look_ahead - 1;
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pred(*back_track, value); --back_track)
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{
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if (--remainder == 0)
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return look_ahead -= skip_offset; // success
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}
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if (remainder > tail_size)
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{
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return last; // no match
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}
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look_ahead += remainder;
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tail_size -= remainder;
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}
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}
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template<typename ForwardIterator, typename Integer, typename Value>
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inline ForwardIterator
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search_n_impl(ForwardIterator first, ForwardIterator last,
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Integer count, const Value& value)
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{
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BOOST_RANGE_CONCEPT_ASSERT((ForwardIteratorConcept<ForwardIterator>));
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BOOST_RANGE_CONCEPT_ASSERT((EqualityComparableConcept<Value>));
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BOOST_RANGE_CONCEPT_ASSERT((EqualityComparableConcept<typename std::iterator_traits<ForwardIterator>::value_type>));
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//BOOST_RANGE_CONCEPT_ASSERT((EqualityComparableConcept2<typename std::iterator_traits<ForwardIterator>::value_type, Value>));
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typedef typename std::iterator_traits<ForwardIterator>::iterator_category cat_t;
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if (count <= 0)
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return first;
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if (count == 1)
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return std::find(first, last, value);
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return range_detail::search_n_impl(first, last, count, value, cat_t());
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}
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template<typename ForwardIterator, typename Integer, typename Value,
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typename BinaryPredicate>
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inline ForwardIterator
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search_n_pred_impl(ForwardIterator first, ForwardIterator last,
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Integer count, const Value& value,
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BinaryPredicate pred)
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{
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BOOST_RANGE_CONCEPT_ASSERT((ForwardIteratorConcept<ForwardIterator>));
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BOOST_RANGE_CONCEPT_ASSERT((
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BinaryPredicateConcept<
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BinaryPredicate,
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typename std::iterator_traits<ForwardIterator>::value_type,
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Value>
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));
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typedef typename std::iterator_traits<ForwardIterator>::iterator_category cat_t;
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if (count <= 0)
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return first;
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if (count == 1)
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{
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while (first != last && !static_cast<bool>(pred(*first, value)))
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++first;
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return first;
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}
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return range_detail::search_n_pred_impl(first, last, count,
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value, pred, cat_t());
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}
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} // namespace range_detail
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namespace range {
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/// \brief template function search
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///
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/// range-based version of the search std algorithm
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///
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/// \pre ForwardRange is a model of the ForwardRangeConcept
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/// \pre Integer is an integral type
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/// \pre Value is a model of the EqualityComparableConcept
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/// \pre ForwardRange's value type is a model of the EqualityComparableConcept
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/// \pre Object's of ForwardRange's value type can be compared for equality with Objects of type Value
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template< class ForwardRange, class Integer, class Value >
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inline BOOST_DEDUCED_TYPENAME range_iterator<ForwardRange>::type
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search_n(ForwardRange& rng, Integer count, const Value& value)
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{
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BOOST_RANGE_CONCEPT_ASSERT((ForwardRangeConcept<ForwardRange>));
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return range_detail::search_n_impl(boost::begin(rng),boost::end(rng), count, value);
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}
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/// \overload
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template< class ForwardRange, class Integer, class Value >
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inline BOOST_DEDUCED_TYPENAME range_iterator<const ForwardRange>::type
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search_n(const ForwardRange& rng, Integer count, const Value& value)
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{
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BOOST_RANGE_CONCEPT_ASSERT((ForwardRangeConcept<const ForwardRange>));
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return range_detail::search_n_impl(boost::begin(rng), boost::end(rng), count, value);
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}
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/// \overload
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template< class ForwardRange, class Integer, class Value,
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class BinaryPredicate >
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inline BOOST_DEDUCED_TYPENAME range_iterator<ForwardRange>::type
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search_n(ForwardRange& rng, Integer count, const Value& value,
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BinaryPredicate binary_pred)
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{
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BOOST_RANGE_CONCEPT_ASSERT((ForwardRangeConcept<ForwardRange>));
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BOOST_RANGE_CONCEPT_ASSERT((BinaryPredicateConcept<BinaryPredicate,
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BOOST_DEDUCED_TYPENAME range_value<ForwardRange>::type, const Value&>));
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return range_detail::search_n_pred_impl(boost::begin(rng), boost::end(rng),
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count, value, binary_pred);
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}
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/// \overload
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template< class ForwardRange, class Integer, class Value,
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class BinaryPredicate >
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inline BOOST_DEDUCED_TYPENAME range_iterator<const ForwardRange>::type
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search_n(const ForwardRange& rng, Integer count, const Value& value,
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BinaryPredicate binary_pred)
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{
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BOOST_RANGE_CONCEPT_ASSERT((ForwardRangeConcept<const ForwardRange>));
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BOOST_RANGE_CONCEPT_ASSERT((BinaryPredicateConcept<BinaryPredicate,
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BOOST_DEDUCED_TYPENAME range_value<const ForwardRange>::type, const Value&>));
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return range_detail::search_n_pred_impl(boost::begin(rng), boost::end(rng),
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count, value, binary_pred);
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}
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// range_return overloads
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/// \overload
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template< range_return_value re, class ForwardRange, class Integer,
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class Value >
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inline BOOST_DEDUCED_TYPENAME range_return<ForwardRange,re>::type
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search_n(ForwardRange& rng, Integer count, const Value& value)
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{
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BOOST_RANGE_CONCEPT_ASSERT((ForwardRangeConcept<ForwardRange>));
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return range_return<ForwardRange,re>::
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pack(range_detail::search_n_impl(boost::begin(rng),boost::end(rng),
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count, value),
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rng);
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}
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/// \overload
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template< range_return_value re, class ForwardRange, class Integer,
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class Value >
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inline BOOST_DEDUCED_TYPENAME range_return<const ForwardRange,re>::type
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search_n(const ForwardRange& rng, Integer count, const Value& value)
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{
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BOOST_RANGE_CONCEPT_ASSERT((ForwardRangeConcept<const ForwardRange>));
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return range_return<const ForwardRange,re>::
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pack(range_detail::search_n_impl(boost::begin(rng), boost::end(rng),
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count, value),
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rng);
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}
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/// \overload
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template< range_return_value re, class ForwardRange, class Integer,
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class Value, class BinaryPredicate >
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inline BOOST_DEDUCED_TYPENAME range_return<ForwardRange,re>::type
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search_n(ForwardRange& rng, Integer count, const Value& value,
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BinaryPredicate pred)
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{
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BOOST_RANGE_CONCEPT_ASSERT((ForwardRangeConcept<ForwardRange>));
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BOOST_RANGE_CONCEPT_ASSERT((BinaryPredicateConcept<BinaryPredicate,
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BOOST_DEDUCED_TYPENAME range_value<ForwardRange>::type,
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const Value&>));
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return range_return<ForwardRange,re>::
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pack(range_detail::search_n_pred_impl(boost::begin(rng),
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boost::end(rng),
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count, value, pred),
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rng);
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}
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/// \overload
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template< range_return_value re, class ForwardRange, class Integer,
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class Value, class BinaryPredicate >
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inline BOOST_DEDUCED_TYPENAME range_return<const ForwardRange,re>::type
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search_n(const ForwardRange& rng, Integer count, const Value& value,
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BinaryPredicate pred)
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{
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BOOST_RANGE_CONCEPT_ASSERT((ForwardRangeConcept<const ForwardRange>));
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BOOST_RANGE_CONCEPT_ASSERT((BinaryPredicateConcept<BinaryPredicate,
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BOOST_DEDUCED_TYPENAME range_value<const ForwardRange>::type,
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const Value&>));
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return range_return<const ForwardRange,re>::
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pack(range_detail::search_n_pred_impl(boost::begin(rng),
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boost::end(rng),
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count, value, pred),
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rng);
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}
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} // namespace range
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using range::search_n;
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} // namespace boost
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#endif // include guard
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