Score::Clone() via CRTP

git-svn-id: https://ws10smt.googlecode.com/svn/trunk@360 ec762483-ff6d-05da-a07a-a48fb63a330f

5 files changed, 17 insertions, 5 deletions

diff --git a/vest/aer_scorer.cc b/vest/aer_scorer.cc
index 81ffae76..25b58b5e 100644
--- a/vest/aer_scorer.cc
+++ b/vest/aer_scorer.cc
@@ -9,7 +9,7 @@
 
 using namespace std;
 
-class AERScore : public Score {
+class AERScore : public ScoreBase<AERScore> {
   friend class AERScorer;
  public:
   AERScore() : num_matches(), num_predicted(), num_in_ref() {}
diff --git a/vest/comb_scorer.cc b/vest/comb_scorer.cc
index a921aa4d..9fc37868 100644
--- a/vest/comb_scorer.cc
+++ b/vest/comb_scorer.cc
@@ -4,7 +4,7 @@
 
 using namespace std;
 
-class BLEUTERCombinationScore : public Score {
+class BLEUTERCombinationScore : public ScoreBase<BLEUTERCombinationScore> {
   friend class BLEUTERCombinationScorer;
  public:
   ~BLEUTERCombinationScore();
diff --git a/vest/scorer.cc b/vest/scorer.cc
index 05269a3b..5671de38 100644
--- a/vest/scorer.cc
+++ b/vest/scorer.cc
@@ -87,7 +87,7 @@ float SentenceScorer::ComputeRefLength(const Sentence &hyp) const {
 
 const std::string* SentenceScorer::GetSource() const { return NULL; }
 
-class SERScore : public Score {
+class SERScore : public ScoreBase<SERScore> {
   friend class SERScorer;
  public:
   SERScore() : correct(0), total(0) {}
@@ -151,7 +151,7 @@ class SERScorer : public SentenceScorer {
   vector<vector<WordID> > refs_;
 };
 
-class BLEUScore : public Score {
+class BLEUScore : public ScoreBase<BLEUScore> {
   friend class BLEUScorerBase;
  public:
   BLEUScore(int n) : correct_ngram_hit_counts(float(0),n), hyp_ngram_counts(float(0),n) {
diff --git a/vest/scorer.h b/vest/scorer.h
index 0d90f378..0c8b380f 100644
--- a/vest/scorer.h
+++ b/vest/scorer.h
@@ -46,6 +46,18 @@ class Score : public boost::intrusive_refcount<Score> {
   virtual void Encode(std::string* out) const = 0;
   static ScoreP GetZero(ScoreType type);
   static ScoreP GetOne(ScoreType type);
+  virtual ScoreP Clone() const = 0;
+protected:
+  Score() {  } // we define these explicitly because refcount is noncopyable
+  Score(Score const& o) {  }
+};
+
+//TODO: make sure default copy ctors for score types do what we want.
+template <class Derived>
+struct ScoreBase : public Score {
+  ScoreP Clone() const  {
+    return ScoreP(new Derived(dynamic_cast<Derived const&>(*this)));
+  }
 };
 
 class SentenceScorer {
diff --git a/vest/ter.cc b/vest/ter.cc
index 8c8494ad..cacc5b00 100644
--- a/vest/ter.cc
+++ b/vest/ter.cc
@@ -412,7 +412,7 @@ class TERScorerImpl {
   }
 };
 
-class TERScore : public Score {
+class TERScore : public ScoreBase<TERScore> {
   friend class TERScorer;
 
  public: