XS_PLUGIN and XS_FILTER implementation

This patch introduces following features:
- XS_PLUGIN context option to add plugins to libxs
- XS_FILTER option to switch between different filter types
- Automatic loading of plug-ins is *not* implemented.

From the implementation point of view:
- standard prefix filter is implemented as a pluggable filter
- trie_t and mtrie_t are joined into a single class
- the code for 0MQ/3.1 compatibility is left in in the form of comments
- new test for testing re-subscriptions is added
Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/object.hpp b/src/object.hpp
index 5b855a5..fabb156 100644
--- a/src/object.hpp
+++ b/src/object.hpp
@@ -22,6 +22,8 @@
 #ifndef __XS_OBJECT_HPP_INCLUDED__
 #define __XS_OBJECT_HPP_INCLUDED__
 
+#include "../include/xs.h"
+
 #include "stdint.hpp"
 
 namespace xs
@@ -64,6 +66,9 @@ namespace xs
         //  Chooses least loaded I/O thread.
         xs::io_thread_t *choose_io_thread (uint64_t affinity_);
 
+        //  Functions related to extensions.
+        xs_filter_t *get_filter (int filter_id_);
+
         //  Derived object can use these functions to send commands
         //  to other objects.
         void send_stop ();