3 files changed, 9 insertions, 0 deletions
diff --git a/mteval/ns.cc b/mteval/ns.cc
index da678b84..788f809a 100644
--- a/mteval/ns.cc
+++ b/mteval/ns.cc
@@ -21,6 +21,10 @@ map<string, EvaluationMetric*> EvaluationMetric::instances_;
 SegmentEvaluator::~SegmentEvaluator() {}
 EvaluationMetric::~EvaluationMetric() {}
 
+bool EvaluationMetric::IsErrorMetric() const {
+  return false;
+}
+
 struct DefaultSegmentEvaluator : public SegmentEvaluator {
   DefaultSegmentEvaluator(const vector<vector<WordID> >& refs, const EvaluationMetric* em) : refs_(refs), em_(em) {}
   void Evaluate(const vector<WordID>& hyp, SufficientStats* out) const {
diff --git a/mteval/ns.h b/mteval/ns.h
index d88c263b..4e4c6975 100644
--- a/mteval/ns.h
+++ b/mteval/ns.h
@@ -94,6 +94,10 @@ class EvaluationMetric {
  public:
   const std::string& MetricId() const { return name_; }
 
+  // returns true for metrics like WER and TER where lower scores are better
+  // false for metrics like BLEU and METEOR where higher scores are better
+  virtual bool IsErrorMetric() const;
+
   virtual unsigned SufficientStatisticsVectorSize() const;
   virtual float ComputeScore(const SufficientStats& stats) const = 0;
   virtual std::string DetailedScore(const SufficientStats& stats) const;
diff --git a/mteval/ns_ter.h b/mteval/ns_ter.h
index 3190fc1b..c5c25413 100644
--- a/mteval/ns_ter.h
+++ b/mteval/ns_ter.h
@@ -9,6 +9,7 @@ class TERMetric : public EvaluationMetric {
   TERMetric() : EvaluationMetric("TER") {}
 
  public:
+  virtual bool IsErrorMetric() const;
   virtual unsigned SufficientStatisticsVectorSize() const;
   virtual std::string DetailedScore(const SufficientStats& stats) const;
   virtual void ComputeSufficientStatistics(const std::vector<WordID>& hyp,