1 files changed, 140 insertions, 0 deletions
diff --git a/boost/compute/algorithm/search_n.hpp b/boost/compute/algorithm/search_n.hpp
new file mode 100644
index 0000000000..9e03111bb0
--- /dev/null
+++ b/boost/compute/algorithm/search_n.hpp
@@ -0,0 +1,140 @@
+//---------------------------------------------------------------------------//
+// Copyright (c) 2014 Roshan <thisisroshansmail@gmail.com>
+//
+// 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
+//
+// See http://boostorg.github.com/compute for more information.
+//---------------------------------------------------------------------------//
+
+#ifndef BOOST_COMPUTE_ALGORITHM_DETAIL_SEARCH_N_HPP
+#define BOOST_COMPUTE_ALGORITHM_DETAIL_SEARCH_N_HPP
+
+#include <iterator>
+
+#include <boost/compute/algorithm/find.hpp>
+#include <boost/compute/container/vector.hpp>
+#include <boost/compute/detail/iterator_range_size.hpp>
+#include <boost/compute/detail/meta_kernel.hpp>
+#include <boost/compute/system.hpp>
+
+namespace boost {
+namespace compute {
+namespace detail {
+
+///
+/// \brief Search kernel class
+///
+/// Subclass of meta_kernel which is capable of performing search_n
+///
+template<class TextIterator, class OutputIterator>
+class search_n_kernel : public meta_kernel
+{
+public:
+    typedef typename std::iterator_traits<TextIterator>::value_type value_type;
+
+    search_n_kernel() : meta_kernel("search_n")
+    {}
+
+    void set_range(TextIterator t_first,
+                   TextIterator t_last,
+                   value_type value,
+                   size_t n,
+                   OutputIterator result)
+    {
+        m_n = n;
+        m_n_arg = add_arg<uint_>("n");
+
+        m_value = value;
+        m_value_arg = add_arg<value_type>("value");
+
+        m_count = iterator_range_size(t_first, t_last);
+        m_count = m_count + 1 - m_n;
+
+        *this <<
+            "uint i = get_global_id(0);\n" <<
+            "uint i1 = i;\n" <<
+            "uint j;\n" <<
+            "for(j = 0; j<n; j++,i++)\n" <<
+            "{\n" <<
+            "   if(value != " << t_first[expr<uint_>("i")] << ")\n" <<
+            "       j = n + 1;\n" <<
+            "}\n" <<
+            "if(j == n)\n" <<
+            result[expr<uint_>("i1")] << " = 1;\n" <<
+            "else\n" <<
+            result[expr<uint_>("i1")] << " = 0;\n";
+    }
+
+    event exec(command_queue &queue)
+    {
+        if(m_count == 0) {
+            return event();
+        }
+
+        set_arg(m_n_arg, uint_(m_n));
+        set_arg(m_value_arg, m_value);
+
+        return exec_1d(queue, 0, m_count);
+    }
+
+private:
+    size_t m_n;
+    size_t m_n_arg;
+    size_t m_count;
+    value_type m_value;
+    size_t m_value_arg;
+};
+
+} //end detail namespace
+
+///
+/// \brief Substring matching algorithm
+///
+/// Searches for the first occurrence of n consecutive occurrences of
+/// value in text [t_first, t_last).
+/// \return Iterator pointing to beginning of first occurrence
+///
+/// \param t_first Iterator pointing to start of text
+/// \param t_last Iterator pointing to end of text
+/// \param n Number of times value repeats
+/// \param value Value which repeats
+/// \param queue Queue on which to execute
+///
+template<class TextIterator, class ValueType>
+inline TextIterator search_n(TextIterator t_first,
+                             TextIterator t_last,
+                             size_t n,
+                             ValueType value,
+                             command_queue &queue = system::default_queue())
+{
+    // there is no need to check if pattern starts at last n - 1 indices
+    vector<uint_> matching_indices(
+        detail::iterator_range_size(t_first, t_last) + 1 - n,
+        queue.get_context()
+    );
+
+    // search_n_kernel puts value 1 at every index in vector where pattern
+    // of n values starts at
+    detail::search_n_kernel<TextIterator,
+                            vector<uint_>::iterator> kernel;
+
+    kernel.set_range(t_first, t_last, value, n, matching_indices.begin());
+    kernel.exec(queue);
+
+    vector<uint_>::iterator index = ::boost::compute::find(
+        matching_indices.begin(), matching_indices.end(), uint_(1), queue
+    );
+
+    // pattern was not found
+    if(index == matching_indices.end())
+        return t_last;
+
+    return t_first + detail::iterator_range_size(matching_indices.begin(), index);
+}
+
+} //end compute namespace
+} //end boost namespace
+
+#endif // BOOST_COMPUTE_ALGORITHM_DETAIL_SEARCH_N_HPP