2 files changed, 21 insertions, 0 deletions
diff --git a/decoder/hg_io.cc b/decoder/hg_io.cc
index 9f0f50fa..d416dbf6 100644
--- a/decoder/hg_io.cc
+++ b/decoder/hg_io.cc
@@ -401,6 +401,26 @@ string HypergraphIO::AsPLF(const Hypergraph& hg, bool include_global_parentheses
   return os.str();
 }
 
+string HypergraphIO::AsPLF(const Lattice& lat, bool include_global_parentheses) {
+  static bool first = true;
+  if (first) { InitEscapes(); first = false; }
+  if (lat.empty()) return "()";
+  ostringstream os;
+  if (include_global_parentheses) os << '(';
+  static const string EPS="*EPS*";
+  for (int i = 0; i < lat.size(); ++i) {
+    const vector<LatticeArc> arcs = lat[i];
+    os << '(';
+    for (int j = 0; j < arcs.size(); ++j) {
+      os << "('" << Escape(TD::Convert(arcs[j].label)) << "',"
+                 << arcs[j].cost << ',' << arcs[j].dist2next << "),";
+    }
+    os << "),";
+  }
+  if (include_global_parentheses) os << ')';
+  return os.str();
+}
+
 namespace PLF {
 
 const string chars = "'\\";
diff --git a/decoder/hg_io.h b/decoder/hg_io.h
index 44817157..4e502a0c 100644
--- a/decoder/hg_io.h
+++ b/decoder/hg_io.h
@@ -30,6 +30,7 @@ struct HypergraphIO {
   static void ReadFromPLF(const std::string& in, Hypergraph* out, int line = 0);
   // return PLF string representation (undefined behavior on non-lattices)
   static std::string AsPLF(const Hypergraph& hg, bool include_global_parentheses = true);
+  static std::string AsPLF(const Lattice& lat, bool include_global_parentheses = true);
   static void PLFtoLattice(const std::string& plf, Lattice* pl);
   static std::string Escape(const std::string& s);  // PLF helper
 };