From 96a32415ab43377cf1575bd3f4f2980f58028209 Mon Sep 17 00:00:00 2001
From: Determinant <ted.sybil@gmail.com>
Date: Fri, 14 Aug 2015 11:51:42 +0800
Subject: add implementation for kaldi io (by ymz)

---
 .../src/tools/openfst/include/fst/rmfinalepsilon.h | 107 +++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 kaldi_io/src/tools/openfst/include/fst/rmfinalepsilon.h

(limited to 'kaldi_io/src/tools/openfst/include/fst/rmfinalepsilon.h')

diff --git a/kaldi_io/src/tools/openfst/include/fst/rmfinalepsilon.h b/kaldi_io/src/tools/openfst/include/fst/rmfinalepsilon.h
new file mode 100644
index 0000000..eb0f937
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/rmfinalepsilon.h
@@ -0,0 +1,107 @@
+// rmfinalepsilon.h
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright 2005-2010 Google, Inc.
+// Author: johans@google.com (Johan Schalkwyk)
+//
+// \file
+// Function to remove of final states that have epsilon only input arcs.
+
+#ifndef FST_LIB_RMFINALEPSILON_H__
+#define FST_LIB_RMFINALEPSILON_H__
+
+#include <tr1/unordered_set>
+using std::tr1::unordered_set;
+using std::tr1::unordered_multiset;
+#include <vector>
+using std::vector;
+
+#include <fst/connect.h>
+#include <fst/mutable-fst.h>
+
+
+namespace fst {
+
+template<class A>
+void RmFinalEpsilon(MutableFst<A>* fst) {
+  typedef typename A::StateId StateId;
+  typedef typename A::Weight Weight;
+
+  // Determine the coaccesibility of states.
+  vector<bool> access;
+  vector<bool> coaccess;
+  uint64 props = 0;
+  SccVisitor<A> scc_visitor(0, &access, &coaccess, &props);
+  DfsVisit(*fst, &scc_visitor);
+
+  // Find potential list of removable final states. These are final states
+  // that have no outgoing transitions or final states that have a
+  // non-coaccessible future. Complexity O(S)
+  unordered_set<StateId> finals;
+  for (StateIterator<Fst<A> > siter(*fst); !siter.Done(); siter.Next()) {
+    StateId s = siter.Value();
+    if (fst->Final(s) != Weight::Zero()) {
+      bool future_coaccess = false;
+      for (ArcIterator<Fst<A> > aiter(*fst, s); !aiter.Done(); aiter.Next()) {
+        const A& arc = aiter.Value();
+        if (coaccess[arc.nextstate]) {
+          future_coaccess = true;
+          break;
+        }
+      }
+      if (!future_coaccess) {
+        finals.insert(s);
+      }
+    }
+  }
+
+  // Move the final weight. Complexity O(E)
+  vector<A> arcs;
+  for (StateIterator<Fst<A> > siter(*fst); !siter.Done(); siter.Next()) {
+    StateId s = siter.Value();
+    Weight w(fst->Final(s));
+
+    arcs.clear();
+    for (ArcIterator<Fst<A> > aiter(*fst, s); !aiter.Done(); aiter.Next()) {
+      const A& arc = aiter.Value();
+      // is next state in the list of finals
+      if (finals.find(arc.nextstate) != finals.end()) {
+        // sum up all epsilon arcs
+        if (arc.ilabel == 0 && arc.olabel == 0) {
+          w = Plus(Times(fst->Final(arc.nextstate), arc.weight), w);
+        } else {
+          arcs.push_back(arc);
+        }
+      } else {
+        arcs.push_back(arc);
+      }
+    }
+
+    // If some arcs (epsilon arcs) were deleted, delete all
+    // arcs and add back only the non epsilon arcs
+    if (arcs.size() < fst->NumArcs(s)) {
+      fst->DeleteArcs(s);
+      fst->SetFinal(s, w);
+      for (size_t i = 0; i < arcs.size(); ++i) {
+        fst->AddArc(s, arcs[i]);
+      }
+    }
+  }
+
+  Connect(fst);
+}
+
+}  // namespace fst
+
+#endif  // FST_LIB_RMFINALEPSILON_H__
-- 
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