1 files changed, 35 insertions, 0 deletions
diff --git a/mteval/ns_wer.cc b/mteval/ns_wer.cc
new file mode 100644
index 00000000..f9b2bbbb
--- /dev/null
+++ b/mteval/ns_wer.cc
@@ -0,0 +1,35 @@
+#include "ns_wer.h"
+#include "tdict.h"
+#include "levenshtein.h"
+
+static const unsigned kNUMFIELDS = 2;
+static const unsigned kEDITDISTANCE = 0;
+static const unsigned kCHARCOUNT = 1;
+
+bool WERMetric::IsErrorMetric() const {
+  return true;
+}
+
+unsigned WERMetric::SufficientStatisticsVectorSize() const {
+  return 2;
+}
+
+void WERMetric::ComputeSufficientStatistics(const std::vector<WordID>& hyp,
+                                            const std::vector<std::vector<WordID> >& refs,
+                                            SufficientStats* out) const {
+  out->fields.resize(kNUMFIELDS);
+  float best_score = hyp.size();
+  for (size_t i = 0; i < refs.size(); ++i) {
+    float score = cdec::LevenshteinDistance(hyp, refs[i]);
+    if (score < best_score) {
+      out->fields[kEDITDISTANCE] = score;
+      out->fields[kCHARCOUNT] = refs[i].size();
+      best_score = score;
+    }
+  }
+}
+
+float WERMetric::ComputeScore(const SufficientStats& stats) const {
+  return stats.fields[kEDITDISTANCE] / stats.fields[kCHARCOUNT];
+}
+