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+/*
+ Copyright (c) Marshall Clow 2010-2012.
+
+ 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)
+
+ For more information, see http://www.boost.org
+*/
+
+#ifndef BOOST_ALGORITHM_BOYER_MOORE_SEARCH_HPP
+#define BOOST_ALGORITHM_BOYER_MOORE_SEARCH_HPP
+
+#include <iterator> // for std::iterator_traits
+
+#include <boost/assert.hpp>
+#include <boost/static_assert.hpp>
+
+#include <boost/range/begin.hpp>
+#include <boost/range/end.hpp>
+
+#include <boost/utility/enable_if.hpp>
+#include <boost/type_traits/is_same.hpp>
+
+#include <boost/algorithm/searching/detail/bm_traits.hpp>
+#include <boost/algorithm/searching/detail/debugging.hpp>
+
+namespace boost { namespace algorithm {
+
+/*
+ A templated version of the boyer-moore searching algorithm.
+
+References:
+ http://www.cs.utexas.edu/users/moore/best-ideas/string-searching/
+ http://www.cs.utexas.edu/~moore/publications/fstrpos.pdf
+
+Explanations: boostinspect:noascii (test tool complains)
+ http://en.wikipedia.org/wiki/Boyer–Moore_string_search_algorithm
+ http://www.movsd.com/bm.htm
+ http://www.cs.ucdavis.edu/~gusfield/cs224f09/bnotes.pdf
+
+The Boyer-Moore search algorithm uses two tables, a "bad character" table
+to tell how far to skip ahead when it hits a character that is not in the pattern,
+and a "good character" table to tell how far to skip ahead when it hits a
+mismatch on a character that _is_ in the pattern.
+
+Requirements:
+ * Random access iterators
+ * The two iterator types (patIter and corpusIter) must
+ "point to" the same underlying type and be comparable.
+ * Additional requirements may be imposed but the skip table, such as:
+ ** Numeric type (array-based skip table)
+ ** Hashable type (map-based skip table)
+*/
+
+ template <typename patIter, typename traits = detail::BM_traits<patIter> >
+ class boyer_moore {
+ typedef typename std::iterator_traits<patIter>::difference_type difference_type;
+ public:
+ boyer_moore ( patIter first, patIter last )
+ : pat_first ( first ), pat_last ( last ),
+ k_pattern_length ( std::distance ( pat_first, pat_last )),
+ skip_ ( k_pattern_length, -1 ),
+ suffix_ ( k_pattern_length + 1 )
+ {
+ this->build_skip_table ( first, last );
+ this->build_suffix_table ( first, last );
+ }
+
+ ~boyer_moore () {}
+
+ /// \fn operator ( corpusIter corpus_first, corpusIter corpus_last )
+ /// \brief Searches the corpus for the pattern that was passed into the constructor
+ ///
+ /// \param corpus_first The start of the data to search (Random Access Iterator)
+ /// \param corpus_last One past the end of the data to search
+ ///
+ template <typename corpusIter>
+ corpusIter operator () ( corpusIter corpus_first, corpusIter corpus_last ) const {
+ BOOST_STATIC_ASSERT (( boost::is_same<
+ typename std::iterator_traits<patIter>::value_type,
+ typename std::iterator_traits<corpusIter>::value_type>::value ));
+
+ if ( corpus_first == corpus_last ) return corpus_last; // if nothing to search, we didn't find it!
+ if ( pat_first == pat_last ) return corpus_first; // empty pattern matches at start
+
+ const difference_type k_corpus_length = std::distance ( corpus_first, corpus_last );
+ // If the pattern is larger than the corpus, we can't find it!
+ if ( k_corpus_length < k_pattern_length )
+ return corpus_last;
+
+ // Do the search
+ return this->do_search ( corpus_first, corpus_last );
+ }
+
+ template <typename Range>
+ typename boost::range_iterator<Range>::type operator () ( Range &r ) const {
+ return (*this) (boost::begin(r), boost::end(r));
+ }
+
+ private:
+/// \cond DOXYGEN_HIDE
+ patIter pat_first, pat_last;
+ const difference_type k_pattern_length;
+ typename traits::skip_table_t skip_;
+ std::vector <difference_type> suffix_;
+
+ /// \fn operator ( corpusIter corpus_first, corpusIter corpus_last, Pred p )
+ /// \brief Searches the corpus for the pattern that was passed into the constructor
+ ///
+ /// \param corpus_first The start of the data to search (Random Access Iterator)
+ /// \param corpus_last One past the end of the data to search
+ /// \param p A predicate used for the search comparisons.
+ ///
+ template <typename corpusIter>
+ corpusIter do_search ( corpusIter corpus_first, corpusIter corpus_last ) const {
+ /* ---- Do the matching ---- */
+ corpusIter curPos = corpus_first;
+ const corpusIter lastPos = corpus_last - k_pattern_length;
+ difference_type j, k, m;
+
+ while ( curPos <= lastPos ) {
+ /* while ( std::distance ( curPos, corpus_last ) >= k_pattern_length ) { */
+ // Do we match right where we are?
+ j = k_pattern_length;
+ while ( pat_first [j-1] == curPos [j-1] ) {
+ j--;
+ // We matched - we're done!
+ if ( j == 0 )
+ return curPos;
+ }
+
+ // Since we didn't match, figure out how far to skip forward
+ k = skip_ [ curPos [ j - 1 ]];
+ m = j - k - 1;
+ if ( k < j && m > suffix_ [ j ] )
+ curPos += m;
+ else
+ curPos += suffix_ [ j ];
+ }
+
+ return corpus_last; // We didn't find anything
+ }
+
+
+ void build_skip_table ( patIter first, patIter last ) {
+ for ( std::size_t i = 0; first != last; ++first, ++i )
+ skip_.insert ( *first, i );
+ }
+
+
+ template<typename Iter, typename Container>
+ void compute_bm_prefix ( Iter pat_first, Iter pat_last, Container &prefix ) {
+ const std::size_t count = std::distance ( pat_first, pat_last );
+ BOOST_ASSERT ( count > 0 );
+ BOOST_ASSERT ( prefix.size () == count );
+
+ prefix[0] = 0;
+ std::size_t k = 0;
+ for ( std::size_t i = 1; i < count; ++i ) {
+ BOOST_ASSERT ( k < count );
+ while ( k > 0 && ( pat_first[k] != pat_first[i] )) {
+ BOOST_ASSERT ( k < count );
+ k = prefix [ k - 1 ];
+ }
+
+ if ( pat_first[k] == pat_first[i] )
+ k++;
+ prefix [ i ] = k;
+ }
+ }
+
+ void build_suffix_table ( patIter pat_first, patIter pat_last ) {
+ const std::size_t count = (std::size_t) std::distance ( pat_first, pat_last );
+
+ if ( count > 0 ) { // empty pattern
+ std::vector<typename std::iterator_traits<patIter>::value_type> reversed(count);
+ (void) std::reverse_copy ( pat_first, pat_last, reversed.begin ());
+
+ std::vector<difference_type> prefix (count);
+ compute_bm_prefix ( pat_first, pat_last, prefix );
+
+ std::vector<difference_type> prefix_reversed (count);
+ compute_bm_prefix ( reversed.begin (), reversed.end (), prefix_reversed );
+
+ for ( std::size_t i = 0; i <= count; i++ )
+ suffix_[i] = count - prefix [count-1];
+
+ for ( std::size_t i = 0; i < count; i++ ) {
+ const std::size_t j = count - prefix_reversed[i];
+ const difference_type k = i - prefix_reversed[i] + 1;
+
+ if (suffix_[j] > k)
+ suffix_[j] = k;
+ }
+ }
+ }
+/// \endcond
+ };
+
+
+/* Two ranges as inputs gives us four possibilities; with 2,3,3,4 parameters
+ Use a bit of TMP to disambiguate the 3-argument templates */
+
+/// \fn boyer_moore_search ( corpusIter corpus_first, corpusIter corpus_last,
+/// patIter pat_first, patIter pat_last )
+/// \brief Searches the corpus for the pattern.
+///
+/// \param corpus_first The start of the data to search (Random Access Iterator)
+/// \param corpus_last One past the end of the data to search
+/// \param pat_first The start of the pattern to search for (Random Access Iterator)
+/// \param pat_last One past the end of the data to search for
+///
+ template <typename patIter, typename corpusIter>
+ corpusIter boyer_moore_search (
+ corpusIter corpus_first, corpusIter corpus_last,
+ patIter pat_first, patIter pat_last )
+ {
+ boyer_moore<patIter> bm ( pat_first, pat_last );
+ return bm ( corpus_first, corpus_last );
+ }
+
+ template <typename PatternRange, typename corpusIter>
+ corpusIter boyer_moore_search (
+ corpusIter corpus_first, corpusIter corpus_last, const PatternRange &pattern )
+ {
+ typedef typename boost::range_iterator<const PatternRange>::type pattern_iterator;
+ boyer_moore<pattern_iterator> bm ( boost::begin(pattern), boost::end (pattern));
+ return bm ( corpus_first, corpus_last );
+ }
+
+ template <typename patIter, typename CorpusRange>
+ typename boost::lazy_disable_if_c<
+ boost::is_same<CorpusRange, patIter>::value, typename boost::range_iterator<CorpusRange> >
+ ::type
+ boyer_moore_search ( CorpusRange &corpus, patIter pat_first, patIter pat_last )
+ {
+ boyer_moore<patIter> bm ( pat_first, pat_last );
+ return bm (boost::begin (corpus), boost::end (corpus));
+ }
+
+ template <typename PatternRange, typename CorpusRange>
+ typename boost::range_iterator<CorpusRange>::type
+ boyer_moore_search ( CorpusRange &corpus, const PatternRange &pattern )
+ {
+ typedef typename boost::range_iterator<const PatternRange>::type pattern_iterator;
+ boyer_moore<pattern_iterator> bm ( boost::begin(pattern), boost::end (pattern));
+ return bm (boost::begin (corpus), boost::end (corpus));
+ }
+
+
+ // Creator functions -- take a pattern range, return an object
+ template <typename Range>
+ boost::algorithm::boyer_moore<typename boost::range_iterator<const Range>::type>
+ make_boyer_moore ( const Range &r ) {
+ return boost::algorithm::boyer_moore
+ <typename boost::range_iterator<const Range>::type> (boost::begin(r), boost::end(r));
+ }
+
+ template <typename Range>
+ boost::algorithm::boyer_moore<typename boost::range_iterator<Range>::type>
+ make_boyer_moore ( Range &r ) {
+ return boost::algorithm::boyer_moore
+ <typename boost::range_iterator<Range>::type> (boost::begin(r), boost::end(r));
+ }
+
+}}
+
+#endif // BOOST_ALGORITHM_BOYER_MOORE_SEARCH_HPP