-stack 0 means no stack pruning

moses/ChartHypothesisCollection.cpp

@@ -190,6 +190,8 @@ void ChartHypothesisCollection::Remove(const HCType::iterator &iter)
  */
 void ChartHypothesisCollection::PruneToSize(ChartManager &manager)
 {
+  if (m_maxHypoStackSize == 0) return; // no limit
+
   if (GetSize() > m_maxHypoStackSize) { // ok, if not over the limit
     priority_queue<float> bestScores;
 

moses/HypothesisStackCubePruning.cpp

@@ -153,6 +153,8 @@ void HypothesisStackCubePruning::AddInitial(Hypothesis *hypo)
 
 void HypothesisStackCubePruning::PruneToSize(size_t newSize)
 {
+  if ( newSize == 0) return; // no limit
+
   if (m_hypos.size() > newSize) { // ok, if not over the limit
     priority_queue<float> bestScores;
 

moses/HypothesisStackNormal.cpp

@@ -153,6 +153,7 @@ bool HypothesisStackNormal::AddPrune(Hypothesis *hypo)
 
 void HypothesisStackNormal::PruneToSize(size_t newSize)
 {
+  if ( newSize == 0) return; // no limit
   if ( size() <= newSize ) return; // ok, if not over the limit
 
   // we need to store a temporary list of hypotheses

moses/Parameter.cpp

@@ -63,7 +63,7 @@ Parameter::Parameter()
   AddParam("phrase-drop-allowed", "da", "if present, allow dropping of source words"); //da = drop any (word); see -du for comparison
   AddParam("report-all-factors", "report all factors in output, not just first");
   AddParam("report-all-factors-in-n-best", "Report all factors in n-best-lists. Default is false");
-  AddParam("stack", "s", "maximum stack size for histogram pruning");
+  AddParam("stack", "s", "maximum stack size for histogram pruning. 0 = unlimited stack size");
   AddParam("stack-diversity", "sd", "minimum number of hypothesis of each coverage in stack (default 0)");
   AddParam("threads","th", "number of threads to use in decoding (defaults to single-threaded)");
   AddParam("translation-details", "T", "for each best hypothesis, report translation details to the given file");