add support for dlopen'd feature functions

1 files changed, 57 insertions, 0 deletions

diff --git a/decoder/ff_external.cc b/decoder/ff_external.cc
new file mode 100644
index 00000000..520e98b1
--- /dev/null
+++ b/decoder/ff_external.cc
@@ -0,0 +1,57 @@
+#include "ff_external.h"
+#include "stringlib.h"
+
+#include <dlfcn.h>
+
+using namespace std;
+
+ExternalFeature::ExternalFeature(const string& param) {
+  size_t pos = param.find(' ');
+  string nparam;
+  string file = param;
+  if (pos < param.size()) {
+    nparam = Trim(param.substr(pos + 1));
+    file = param.substr(0, pos);
+  }
+  if (file.size() < 1) {
+    cerr << "External requires a path to a dynamic library!\n";
+    abort();
+  }
+  lib_handle = dlopen(file.c_str(), RTLD_LAZY);
+  if (!lib_handle) {
+    cerr << "dlopen reports: " << dlerror() << endl;
+    cerr << "Did you provide a full path to the dynamic library?\n";
+    abort();
+  }
+  FeatureFunction* (*fn)(const string&) =
+    (FeatureFunction* (*)(const string&))(dlsym(lib_handle, "create_ff"));
+  if (!fn) {
+    cerr << "dlsym reports: " << dlerror() << endl;
+    abort();
+  }
+  ff_ext = (*fn)(nparam);
+}
+
+ExternalFeature::~ExternalFeature() {
+  delete ff_ext;
+  dlclose(lib_handle);
+}
+
+void ExternalFeature::PrepareForInput(const SentenceMetadata& smeta) {
+  ff_ext->PrepareForInput(smeta);
+}
+
+void ExternalFeature::FinalTraversalFeatures(const void* context,
+                                             SparseVector<double>* features) const {
+  ff_ext->FinalTraversalFeatures(context, features);
+}
+
+void ExternalFeature::TraversalFeaturesImpl(const SentenceMetadata& smeta,
+                                     const Hypergraph::Edge& edge,
+                                     const std::vector<const void*>& ant_contexts,
+                                     FeatureVector* features,
+                                     FeatureVector* estimated_features,
+                                     void* context) const {
+  ff_ext->TraversalFeaturesImpl(smeta, edge, ant_contexts, features, estimated_features, context);
+}
+