Driver: moved ProgramCache to a separate file

lib/driver/program_cache.cpp

@@ -0,0 +1,39 @@
+#include "isaac/driver/program_cache.h"
+
+namespace isaac
+{
+
+namespace driver
+{
+
+Program & ProgramCache::add(Context const & context, std::string const & name, std::string const & src)
+{
+    std::map<std::string, Program>::iterator it = cache_.find(name);
+    if(it==cache_.end())
+    {
+        std::string extensions;
+        std::string ext = "cl_khr_fp64";
+        if(context.device().extensions().find(ext)!=std::string::npos)
+          extensions = "#pragma OPENCL EXTENSION " + ext + " : enable\n";
+        return cache_.insert(std::make_pair(name, driver::Program(context, extensions + src))).first->second;
+    }
+    return it->second;
+}
+
+Program const * ProgramCache::find(const std::string &name)
+{
+    std::map<std::string, Program>::const_iterator it = cache_.find(name);
+    if(it==cache_.end())
+        return NULL;
+    return &(it->second);
+}
+
+void ProgramCache::clear()
+{
+    cache_.clear();
+}
+
+}
+
+}
+