move backoff parameter into decode graph class

moses/DecodeGraph.h

@@ -40,6 +40,7 @@ protected:
   std::list<const DecodeStep*> m_steps;
   size_t m_position;
   size_t m_maxChartSpan;
+  size_t m_backoff;
 
 public:
   /**
@@ -47,8 +48,9 @@ public:
     **/
   DecodeGraph(size_t position)
     : m_position(position)
-    , m_maxChartSpan(NOT_FOUND) {
-  }
+    , m_maxChartSpan(NOT_FOUND)
+	, m_backoff(0)
+	{}
 
   // for chart decoding
   DecodeGraph(size_t position, size_t maxChartSpan)
@@ -82,6 +84,14 @@ public:
     return m_maxChartSpan;
   }
 
+  size_t GetBackoff() const {
+    return m_backoff;
+  }
+
+  void SetBackoff(size_t backoff){
+    m_backoff = backoff;
+  }
+
   size_t GetPosition() const {
     return m_position;
   }

moses/StaticData.cpp

@@ -744,13 +744,14 @@ bool StaticData::LoadDecodeGraphs()
 
   // set maximum n-gram size for backoff approach to decoding paths
   // default is always use subsequent paths (value = 0)
-  for(size_t i=0; i<m_decodeGraphs.size(); i++) {
-    m_decodeGraphBackoff.push_back( 0 );
-  }
   // if specified, record maxmimum unseen n-gram size
   const vector<string> &backoffVector = m_parameter->GetParam("decoding-graph-backoff");
   for(size_t i=0; i<m_decodeGraphs.size() && i<backoffVector.size(); i++) {
-    m_decodeGraphBackoff[i] = Scan<size_t>(backoffVector[i]);
+	DecodeGraph &decodeGraph = *m_decodeGraphs[i];
+
+	if (i < backoffVector.size()) {
+		decodeGraph.SetBackoff(Scan<size_t>(backoffVector[i]));
+	}
   }
 
   return true;

moses/StaticData.h

@@ -70,7 +70,7 @@ protected:
   mutable ScoreComponentCollection m_allWeights;
 
   std::vector<DecodeGraph*> m_decodeGraphs;
-  std::vector<size_t> m_decodeGraphBackoff;
+
   // Initial	= 0 = can be used when creating poss trans
   // Other		= 1 = used to calculate LM score once all steps have been processed
   float
@@ -720,9 +720,6 @@ public:
   const std::vector<DecodeGraph*>& GetDecodeGraphs() const {
     return m_decodeGraphs;
   }
-  const std::vector<size_t>& GetDecodeGraphBackoff() const {
-    return m_decodeGraphBackoff;
-  }
 
   //sentence (and thread) specific initialisationn and cleanup
   void InitializeForInput(const InputType& source) const;

moses/TranslationOptionCollection.cpp

@@ -371,7 +371,6 @@ void TranslationOptionCollection::CreateTranslationOptions()
 
   // there may be multiple decoding graphs (factorizations of decoding)
   const vector <DecodeGraph*> &decodeGraphList = StaticData::Instance().GetDecodeGraphs();
-  const vector <size_t> &decodeGraphBackoff = StaticData::Instance().GetDecodeGraphBackoff();
 
   // length of the sentence
   const size_t size = m_source.GetSize();
@@ -383,6 +382,7 @@ void TranslationOptionCollection::CreateTranslationOptions()
     }
 
     const DecodeGraph &decodeGraph = *decodeGraphList[graphInd];
+    size_t backoff = decodeGraph.GetBackoff();
     // generate phrases that start at startPos ...
     for (size_t startPos = 0 ; startPos < size; startPos++) {
       size_t maxSize = size - startPos; // don't go over end of sentence
@@ -392,8 +392,8 @@ void TranslationOptionCollection::CreateTranslationOptions()
       // ... and that end at endPos
       for (size_t endPos = startPos ; endPos < startPos + maxSize ; endPos++) {
         if (graphInd > 0 && // only skip subsequent graphs
-            decodeGraphBackoff[graphInd] != 0 && // use of backoff specified
-            (endPos-startPos+1 >= decodeGraphBackoff[graphInd] || // size exceeds backoff limit or ...
+        	backoff != 0 && // use of backoff specified
+            (endPos-startPos+1 >= backoff || // size exceeds backoff limit or ...
              m_collection[startPos][endPos-startPos].size() > 0)) { // no phrases found so far
           VERBOSE(3,"No backoff to graph " << graphInd << " for span [" << startPos << ";" << endPos << "]" << endl);
           // do not create more options