ndnboost: Include boost::iostreams for internal use.
diff --git a/include/ndnboost/regex/v4/mem_block_cache.hpp b/include/ndnboost/regex/v4/mem_block_cache.hpp
new file mode 100644
index 0000000..fe71a3b
--- /dev/null
+++ b/include/ndnboost/regex/v4/mem_block_cache.hpp
@@ -0,0 +1,99 @@
+ /*
+ * Copyright (c) 2002
+ * John Maddock
+ *
+ * Use, modification and distribution are subject to 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)
+ *
+ */
+
+ /*
+  *   LOCATION:    see http://www.boost.org for most recent version.
+  *   FILE         mem_block_cache.hpp
+  *   VERSION      see <ndnboost/version.hpp>
+  *   DESCRIPTION: memory block cache used by the non-recursive matcher.
+  */
+
+#ifndef NDNBOOST_REGEX_V4_MEM_BLOCK_CACHE_HPP
+#define NDNBOOST_REGEX_V4_MEM_BLOCK_CACHE_HPP
+
+#include <new>
+#ifdef NDNBOOST_HAS_THREADS
+#include <ndnboost/regex/pending/static_mutex.hpp>
+#endif
+
+#ifdef NDNBOOST_HAS_ABI_HEADERS
+#  include NDNBOOST_ABI_PREFIX
+#endif
+
+namespace ndnboost{
+namespace re_detail{
+
+struct mem_block_node
+{
+   mem_block_node* next;
+};
+
+struct mem_block_cache
+{
+   // this member has to be statically initialsed:
+   mem_block_node* next;
+   unsigned cached_blocks;
+#ifdef NDNBOOST_HAS_THREADS
+   ndnboost::static_mutex mut;
+#endif
+
+   ~mem_block_cache()
+   {
+      while(next)
+      {
+         mem_block_node* old = next;
+         next = next->next;
+         ::operator delete(old);
+      }
+   }
+   void* get()
+   {
+#ifdef NDNBOOST_HAS_THREADS
+      ndnboost::static_mutex::scoped_lock g(mut);
+#endif
+     if(next)
+      {
+         mem_block_node* result = next;
+         next = next->next;
+         --cached_blocks;
+         return result;
+      }
+      return ::operator new(NDNBOOST_REGEX_BLOCKSIZE);
+   }
+   void put(void* p)
+   {
+#ifdef NDNBOOST_HAS_THREADS
+      ndnboost::static_mutex::scoped_lock g(mut);
+#endif
+      if(cached_blocks >= NDNBOOST_REGEX_MAX_CACHE_BLOCKS)
+      {
+         ::operator delete(p);
+      }
+      else
+      {
+         mem_block_node* old = static_cast<mem_block_node*>(p);
+         old->next = next;
+         next = old;
+         ++cached_blocks;
+      }
+   }
+};
+
+extern mem_block_cache block_cache;
+
+}
+} // namespace ndnboost
+
+#ifdef NDNBOOST_HAS_ABI_HEADERS
+#  include NDNBOOST_ABI_SUFFIX
+#endif
+
+#endif
+