port beam threshold from Moses

moses-smt · Dec 1, 2016 · 0f12557 · 0f12557
1 parent 288af6e
commit 0f12557
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Showing 3 changed files with 24 additions and 2 deletions.
diff --git a/contrib/moses2/HypothesisColl.cpp b/contrib/moses2/HypothesisColl.cpp
@@ -22,6 +22,8 @@ HypothesisColl::HypothesisColl(const ManagerBase &mgr) :
     		m_coll(MemPoolAllocator<const HypothesisBase*>(mgr.GetPool())), m_sortedHypos(
     				NULL)
 {
+  m_bestScore = -std::numeric_limits<float>::infinity();
+  m_worstScore = -std::numeric_limits<float>::infinity();
 }
 
 const HypothesisBase *HypothesisColl::GetBestHypo() const
@@ -50,6 +52,23 @@ void HypothesisColl::Add(
 		Recycler<HypothesisBase*> &hypoRecycle,
 		ArcLists &arcLists)
 {
+  SCORE futureScore = hypo->GetFutureScore();
+  if (futureScore < m_worstScore) {
+    // beam threshold
+    hypoRecycle.Recycle(hypo);
+    return;
+  }
+
+  if (futureScore > m_bestScore) {
+    m_bestScore = hypo->GetFutureScore();
+
+    // this may also affect the worst score
+    SCORE beamWidth = system.options.search.beam_width;
+    if ( m_bestScore + beamWidth > m_worstScore ) {
+      m_worstScore = m_bestScore + beamWidth;
+    }
+  }
+
 	StackAdd added = Add(hypo);
 
 	size_t nbestSize = system.options.nbest.nbest_size;

diff --git a/contrib/moses2/HypothesisColl.h b/contrib/moses2/HypothesisColl.h
@@ -60,6 +60,9 @@ class HypothesisColl
   _HCType m_coll;
   mutable Hypotheses *m_sortedHypos;
 
+  SCORE m_bestScore;
+  SCORE m_worstScore;
+
   StackAdd Add(const HypothesisBase *hypo);
   void SortAndPruneHypos(const ManagerBase &mgr, ArcLists &arcLists) const;
 

diff --git a/contrib/moses2/legacy/Parameter.cpp b/contrib/moses2/legacy/Parameter.cpp
@@ -79,8 +79,8 @@ Parameter::Parameter()
   desc += "8=tree-to-string (SCFG-based)\n";
   desc += "9=forest-to-string";
   AddParam(search_opts, "search-algorithm", desc);
-  //AddParam(search_opts, "beam-threshold", "b",
-  //    "threshold for threshold pruning");
+  AddParam(search_opts, "beam-threshold", "b",
+      "threshold for threshold pruning");
   //AddParam(search_opts, "early-discarding-threshold", "edt",
   //    "threshold for constructing hypotheses based on estimate cost");
   AddParam(search_opts, "stack", "s",