1 files changed, 42 insertions, 0 deletions
diff --git a/decoder/ff_source_path.cc b/decoder/ff_source_path.cc
new file mode 100644
index 00000000..2a3bee2e
--- /dev/null
+++ b/decoder/ff_source_path.cc
@@ -0,0 +1,42 @@
+#include "ff_source_path.h"
+
+#include "hg.h"
+
+using namespace std;
+
+SourcePathFeatures::SourcePathFeatures(const string& param) : FeatureFunction(sizeof(int)) {}
+
+void SourcePathFeatures::FireBigramFeature(WordID prev, WordID cur, SparseVector<double>* features) const {
+  int& fid = bigram_fids[prev][cur];
+  if (!fid) fid = FD::Convert("SB:"+TD::Convert(prev) + "_" + TD::Convert(cur));
+  if (fid) features->add_value(fid, 1.0);
+}
+
+void SourcePathFeatures::FireUnigramFeature(WordID cur, SparseVector<double>* features) const {
+  int& fid = unigram_fids[cur];
+  if (!fid) fid = FD::Convert("SU:" + TD::Convert(cur));
+  if (fid) features->add_value(fid, 1.0);
+}
+
+void SourcePathFeatures::TraversalFeaturesImpl(const SentenceMetadata& smeta,
+                                               const HG::Edge& edge,
+                                               const vector<const void*>& ant_contexts,
+                                               SparseVector<double>* features,
+                                               SparseVector<double>* estimated_features,
+                                               void* context) const {
+  WordID* res = reinterpret_cast<WordID*>(context);
+  const vector<int>& f = edge.rule_->f();
+  int prev = 0;
+  unsigned ntc = 0;
+  for (unsigned i = 0; i < f.size(); ++i) {
+    int cur = f[i];
+    if (cur < 0)
+      cur = *reinterpret_cast<const WordID*>(ant_contexts[ntc++]);
+    else
+      FireUnigramFeature(cur, features);
+    if (prev) FireBigramFeature(prev, cur, features);
+    prev = cur;
+  }
+  *res = prev;
+}
+