Merge pull request #15 from qindazhu/haowen-fsa-property

only kFinalSymobl arcs enter final state

Author: danpovey

k2/csrc/properties.cc

@@ -26,8 +26,9 @@ bool IsValid(const Fsa &fsa) {
   // the number of arcs in one state
   int32_t num_arcs = 0;
   for (const auto &arc : fsa.arcs) {
-    // only epsilon arcs enter the final state
-    if (arc.dest_state == final_state && arc.label != kEpsilon) return false;
+    // only kFinalSymbol arcs enter the final state
+    if (arc.dest_state == final_state && arc.label != kFinalSymbol)
+      return false;
     if (arc.src_state == state) {
       ++num_arcs;
     } else {

k2/csrc/properties.h

@@ -28,7 +28,7 @@ enum Properties {
 /*
   `fsa` is valid if:
   1. it is empty, if not, it contains at least two states.
-  2. only epsilon arcs enter the final state.
+  2. only kFinalSymbol arcs enter the final state.
   3. every state contains at least one arc except the final state.
   4. `arcs_indexes` and `arcs` in this state are not consistent.
   TODO(haowen): add more rules?

k2/csrc/properties_test.cc

@@ -28,7 +28,7 @@ TEST(Properties, IsNotValid) {
     EXPECT_FALSE(is_valid);
   }
 
-  // only epsilon arcs enter the final state
+  // only kFinalSymbol arcs enter the final state
   {
     Fsa fsa;
     std::vector<Arc> arcs = {
@@ -113,8 +113,8 @@ TEST(Properties, IsValid) {
   {
     std::vector<Arc> arcs = {
         {0, 1, 0},
-        {0, 2, 0},
-        {1, 2, 0},
+        {0, 2, kFinalSymbol},
+        {1, 2, kFinalSymbol},
     };
     std::vector<int32_t> arc_indexes = {0, 2, 3};
     Fsa fsa;