add implementation for kaldi io (by ymz)

15 files changed, 3614 insertions, 0 deletions

diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/compile-strings.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/compile-strings.h
new file mode 100644
index 0000000..ca247db
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/compile-strings.h
@@ -0,0 +1,304 @@
+
+// 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.
+// Authors: [email protected] (Cyril Allauzen)
+//          [email protected] (Terry Tai)
+//          [email protected] (Jake Ratkiewicz)
+
+
+#ifndef FST_EXTENSIONS_FAR_COMPILE_STRINGS_H_
+#define FST_EXTENSIONS_FAR_COMPILE_STRINGS_H_
+
+#include <libgen.h>
+#include <string>
+#include <vector>
+using std::vector;
+
+#include <fst/extensions/far/far.h>
+#include <fst/string.h>
+
+namespace fst {
+
+// Construct a reader that provides FSTs from a file (stream) either on a
+// line-by-line basis or on a per-stream basis.  Note that the freshly
+// constructed reader is already set to the first input.
+//
+// Sample Usage:
+//   for (StringReader<Arc> reader(...); !reader.Done(); reader.Next()) {
+//     Fst *fst = reader.GetVectorFst();
+//   }
+template <class A>
+class StringReader {
+ public:
+  typedef A Arc;
+  typedef typename A::Label Label;
+  typedef typename A::Weight Weight;
+  typedef typename StringCompiler<A>::TokenType TokenType;
+
+  enum EntryType { LINE = 1, FILE = 2 };
+
+  StringReader(istream &istrm,
+               const string &source,
+               EntryType entry_type,
+               TokenType token_type,
+               bool allow_negative_labels,
+               const SymbolTable *syms = 0,
+               Label unknown_label = kNoStateId)
+      : nline_(0), strm_(istrm), source_(source), entry_type_(entry_type),
+        token_type_(token_type), symbols_(syms), done_(false),
+        compiler_(token_type, syms, unknown_label, allow_negative_labels) {
+    Next();  // Initialize the reader to the first input.
+  }
+
+  bool Done() {
+    return done_;
+  }
+
+  void Next() {
+    VLOG(1) << "Processing source " << source_ << " at line " << nline_;
+    if (!strm_) {                    // We're done if we have no more input.
+      done_ = true;
+      return;
+    }
+    if (entry_type_ == LINE) {
+      getline(strm_, content_);
+      ++nline_;
+    } else {
+      content_.clear();
+      string line;
+      while (getline(strm_, line)) {
+        ++nline_;
+        content_.append(line);
+        content_.append("\n");
+      }
+    }
+    if (!strm_ && content_.empty())  // We're also done if we read off all the
+      done_ = true;                  // whitespace at the end of a file.
+  }
+
+  VectorFst<A> *GetVectorFst(bool keep_symbols = false) {
+    VectorFst<A> *fst = new VectorFst<A>;
+    if (keep_symbols) {
+      fst->SetInputSymbols(symbols_);
+      fst->SetOutputSymbols(symbols_);
+    }
+    if (compiler_(content_, fst)) {
+      return fst;
+    } else {
+      delete fst;
+      return NULL;
+    }
+  }
+
+  CompactFst<A, StringCompactor<A> > *GetCompactFst(bool keep_symbols = false) {
+    CompactFst<A, StringCompactor<A> > *fst;
+    if (keep_symbols) {
+      VectorFst<A> tmp;
+      tmp.SetInputSymbols(symbols_);
+      tmp.SetOutputSymbols(symbols_);
+      fst = new CompactFst<A, StringCompactor<A> >(tmp);
+    } else {
+      fst = new CompactFst<A, StringCompactor<A> >;
+    }
+    if (compiler_(content_, fst)) {
+      return fst;
+    } else {
+      delete fst;
+      return NULL;
+    }
+  }
+
+ private:
+  size_t nline_;
+  istream &strm_;
+  string source_;
+  EntryType entry_type_;
+  TokenType token_type_;
+  const SymbolTable *symbols_;
+  bool done_;
+  StringCompiler<A> compiler_;
+  string content_;  // The actual content of the input stream's next FST.
+
+  DISALLOW_COPY_AND_ASSIGN(StringReader);
+};
+
+// Compute the minimal length required to encode each line number as a decimal
+// number.
+int KeySize(const char *filename);
+
+template <class Arc>
+void FarCompileStrings(const vector<string> &in_fnames,
+                       const string &out_fname,
+                       const string &fst_type,
+                       const FarType &far_type,
+                       int32 generate_keys,
+                       FarEntryType fet,
+                       FarTokenType tt,
+                       const string &symbols_fname,
+                       const string &unknown_symbol,
+                       bool keep_symbols,
+                       bool initial_symbols,
+                       bool allow_negative_labels,
+                       bool file_list_input,
+                       const string &key_prefix,
+                       const string &key_suffix) {
+  typename StringReader<Arc>::EntryType entry_type;
+  if (fet == FET_LINE) {
+    entry_type = StringReader<Arc>::LINE;
+  } else if (fet == FET_FILE) {
+    entry_type = StringReader<Arc>::FILE;
+  } else {
+    FSTERROR() << "FarCompileStrings: unknown entry type";
+    return;
+  }
+
+  typename StringCompiler<Arc>::TokenType token_type;
+  if (tt == FTT_SYMBOL) {
+    token_type = StringCompiler<Arc>::SYMBOL;
+  } else if (tt == FTT_BYTE) {
+    token_type = StringCompiler<Arc>::BYTE;
+  } else if (tt == FTT_UTF8) {
+    token_type = StringCompiler<Arc>::UTF8;
+  } else {
+    FSTERROR() << "FarCompileStrings: unknown token type";
+    return;
+  }
+
+  bool compact;
+  if (fst_type.empty() || (fst_type == "vector")) {
+    compact = false;
+  } else if (fst_type == "compact") {
+    compact = true;
+  } else {
+    FSTERROR() << "FarCompileStrings: unknown fst type: "
+               << fst_type;
+    return;
+  }
+
+  const SymbolTable *syms = 0;
+  typename Arc::Label unknown_label = kNoLabel;
+  if (!symbols_fname.empty()) {
+    SymbolTableTextOptions opts;
+    opts.allow_negative = allow_negative_labels;
+    syms = SymbolTable::ReadText(symbols_fname, opts);
+    if (!syms) {
+      FSTERROR() << "FarCompileStrings: error reading symbol table: "
+                 << symbols_fname;
+      return;
+    }
+    if (!unknown_symbol.empty()) {
+      unknown_label = syms->Find(unknown_symbol);
+      if (unknown_label == kNoLabel) {
+        FSTERROR() << "FarCompileStrings: unknown label \"" << unknown_label
+                   << "\" missing from symbol table: " << symbols_fname;
+        return;
+      }
+    }
+  }
+
+  FarWriter<Arc> *far_writer =
+      FarWriter<Arc>::Create(out_fname, far_type);
+  if (!far_writer) return;
+
+  vector<string> inputs;
+  if (file_list_input) {
+    for (int i = 1; i < in_fnames.size(); ++i) {
+      istream *istrm = in_fnames.empty() ? &cin :
+          new ifstream(in_fnames[i].c_str());
+      string str;
+      while (getline(*istrm, str))
+        inputs.push_back(str);
+      if (!in_fnames.empty())
+        delete istrm;
+    }
+  } else {
+    inputs = in_fnames;
+  }
+
+  for (int i = 0, n = 0; i < inputs.size(); ++i) {
+    if (generate_keys == 0 && inputs[i].empty()) {
+      FSTERROR() << "FarCompileStrings: read from a file instead of stdin or"
+                 << " set the --generate_keys flags.";
+      delete far_writer;
+      delete syms;
+      return;
+    }
+    int key_size = generate_keys ? generate_keys :
+        (entry_type == StringReader<Arc>::FILE ? 1 :
+         KeySize(inputs[i].c_str()));
+    istream *istrm = inputs[i].empty() ? &cin :
+        new ifstream(inputs[i].c_str());
+
+    bool keep_syms = keep_symbols;
+    for (StringReader<Arc> reader(
+             *istrm, inputs[i].empty() ? "stdin" : inputs[i],
+             entry_type, token_type, allow_negative_labels,
+             syms, unknown_label);
+         !reader.Done();
+         reader.Next()) {
+      ++n;
+      const Fst<Arc> *fst;
+      if (compact)
+        fst = reader.GetCompactFst(keep_syms);
+      else
+        fst = reader.GetVectorFst(keep_syms);
+      if (initial_symbols)
+        keep_syms = false;
+      if (!fst) {
+        FSTERROR() << "FarCompileStrings: compiling string number " << n
+                   << " in file " << inputs[i] << " failed with token_type = "
+                   << (tt == FTT_BYTE ? "byte" :
+                       (tt == FTT_UTF8 ? "utf8" :
+                        (tt == FTT_SYMBOL ? "symbol" : "unknown")))
+                   << " and entry_type = "
+                   << (fet == FET_LINE ? "line" :
+                       (fet == FET_FILE ? "file" : "unknown"));
+        delete far_writer;
+        delete syms;
+        if (!inputs[i].empty()) delete istrm;
+        return;
+      }
+      ostringstream keybuf;
+      keybuf.width(key_size);
+      keybuf.fill('0');
+      keybuf << n;
+      string key;
+      if (generate_keys > 0) {
+        key = keybuf.str();
+      } else {
+        char* filename = new char[inputs[i].size() + 1];
+        strcpy(filename, inputs[i].c_str());
+        key = basename(filename);
+        if (entry_type != StringReader<Arc>::FILE) {
+          key += "-";
+          key += keybuf.str();
+        }
+        delete[] filename;
+      }
+      far_writer->Add(key_prefix + key + key_suffix, *fst);
+      delete fst;
+    }
+    if (generate_keys == 0)
+      n = 0;
+    if (!inputs[i].empty())
+      delete istrm;
+  }
+
+  delete far_writer;
+}
+
+}  // namespace fst
+
+
+#endif  // FST_EXTENSIONS_FAR_COMPILE_STRINGS_H_
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/create.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/create.h
new file mode 100644
index 0000000..edb31e7
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/create.h
@@ -0,0 +1,87 @@
+// create-main.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: [email protected] (Michael Riley)
+// Modified: [email protected] (Jake Ratkiewicz) to use new dispatch
+//
+// \file
+// Creates a finite-state archive from component FSTs.  Includes
+// helper function for farcreate.cc that templates the main on the arc
+// type to support multiple and extensible arc types.
+//
+
+#ifndef FST_EXTENSIONS_FAR_CREATE_H__
+#define FST_EXTENSIONS_FAR_CREATE_H__
+
+#include <libgen.h>
+#include <string>
+#include <vector>
+using std::vector;
+
+#include <fst/extensions/far/far.h>
+
+namespace fst {
+
+template <class Arc>
+void FarCreate(const vector<string> &in_fnames,
+               const string &out_fname,
+               const int32 generate_keys,
+               const bool file_list_input,
+               const FarType &far_type,
+               const string &key_prefix,
+               const string &key_suffix) {
+  FarWriter<Arc> *far_writer =
+      FarWriter<Arc>::Create(out_fname, far_type);
+  if (!far_writer) return;
+
+  vector<string> inputs;
+  if (file_list_input) {
+    for (int i = 1; i < in_fnames.size(); ++i) {
+      ifstream istrm(in_fnames[i].c_str());
+      string str;
+      while (getline(istrm, str))
+        inputs.push_back(str);
+    }
+  } else {
+    inputs = in_fnames;
+  }
+
+  for (int i = 0; i < inputs.size(); ++i) {
+    Fst<Arc> *ifst = Fst<Arc>::Read(inputs[i]);
+    if (!ifst) return;
+    string key;
+    if (generate_keys > 0) {
+      ostringstream keybuf;
+      keybuf.width(generate_keys);
+      keybuf.fill('0');
+      keybuf << i + 1;
+      key = keybuf.str();
+    } else {
+      char* filename = new char[inputs[i].size() + 1];
+      strcpy(filename, inputs[i].c_str());
+      key = basename(filename);
+      delete[] filename;
+    }
+
+    far_writer->Add(key_prefix + key + key_suffix, *ifst);
+    delete ifst;
+  }
+
+  delete far_writer;
+}
+
+}  // namespace fst
+
+#endif  // FST_EXTENSIONS_FAR_CREATE_H__
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/equal.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/equal.h
new file mode 100644
index 0000000..be82e2d
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/equal.h
@@ -0,0 +1,99 @@
+
+// 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: [email protected] (Cyril Allauzen)
+
+#ifndef FST_EXTENSIONS_FAR_EQUAL_H_
+#define FST_EXTENSIONS_FAR_EQUAL_H_
+
+#include <string>
+
+#include <fst/extensions/far/far.h>
+#include <fst/equal.h>
+
+namespace fst {
+
+template <class Arc>
+bool FarEqual(const string &filename1,
+             const string &filename2,
+             float delta = kDelta,
+             const string &begin_key = string(),
+             const string &end_key = string()) {
+
+  FarReader<Arc> *reader1 = FarReader<Arc>::Open(filename1);
+  FarReader<Arc> *reader2 = FarReader<Arc>::Open(filename2);
+  if (!reader1 || !reader2) {
+    delete reader1;
+    delete reader2;
+    VLOG(1) << "FarEqual: cannot open input Far file(s)";
+    return false;
+  }
+
+  if (!begin_key.empty()) {
+    bool find_begin1 = reader1->Find(begin_key);
+    bool find_begin2 = reader2->Find(begin_key);
+    if (!find_begin1 || !find_begin2) {
+      bool ret = !find_begin1 && !find_begin2;
+      if (!ret) {
+        VLOG(1) << "FarEqual: key \"" << begin_key << "\" missing from "
+                << (find_begin1 ? "second" : "first") << " archive.";
+      }
+      delete reader1;
+      delete reader2;
+      return ret;
+    }
+  }
+
+  for(; !reader1->Done() && !reader2->Done();
+      reader1->Next(), reader2->Next()) {
+    const string key1 = reader1->GetKey();
+    const string key2 = reader2->GetKey();
+    if (!end_key.empty() && end_key < key1 && end_key < key2) {
+      delete reader1;
+      delete reader2;
+      return true;
+    }
+    if (key1 != key2) {
+      VLOG(1) << "FarEqual: mismatched keys \""
+              << key1 << "\" <> \"" << key2 << "\".";
+      delete reader1;
+      delete reader2;
+      return false;
+    }
+    if (!Equal(reader1->GetFst(), reader2->GetFst(), delta)) {
+      VLOG(1) << "FarEqual: Fsts for key \"" << key1 << "\" are not equal.";
+      delete reader1;
+      delete reader2;
+      return false;
+    }
+  }
+
+  if (!reader1->Done() || !reader2->Done()) {
+    VLOG(1) << "FarEqual: key \""
+            << (reader1->Done() ? reader2->GetKey() : reader1->GetKey())
+            << "\" missing form " << (reader2->Done() ? "first" : "second")
+            << " archive.";
+    delete reader1;
+    delete reader2;
+    return false;
+  }
+
+  delete reader1;
+  delete reader2;
+  return true;
+}
+
+}  // namespace fst
+
+#endif  // FST_EXTENSIONS_FAR_EQUAL_H_
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/extract.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/extract.h
new file mode 100644
index 0000000..95866de
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/extract.h
@@ -0,0 +1,140 @@
+// extract-main.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: [email protected] (Michael Riley)
+// Modified: [email protected] (Jake Ratkiewicz) to use the new arc-dispatch
+
+// \file
+// Extracts component FSTs from an finite-state archive.
+//
+
+#ifndef FST_EXTENSIONS_FAR_EXTRACT_H__
+#define FST_EXTENSIONS_FAR_EXTRACT_H__
+
+#include <string>
+#include <vector>
+using std::vector;
+
+#include <fst/extensions/far/far.h>
+
+namespace fst {
+
+template<class Arc>
+inline void FarWriteFst(const Fst<Arc>* fst, string key,
+                        string* okey, int* nrep,
+                        const int32 &generate_filenames, int i,
+                        const string &filename_prefix,
+                        const string &filename_suffix) {
+  if (key == *okey)
+    ++*nrep;
+  else
+    *nrep = 0;
+
+  *okey = key;
+
+  string ofilename;
+  if (generate_filenames) {
+    ostringstream tmp;
+    tmp.width(generate_filenames);
+    tmp.fill('0');
+    tmp << i;
+    ofilename = tmp.str();
+  } else {
+    if (*nrep > 0) {
+      ostringstream tmp;
+      tmp << '.' << nrep;
+      key.append(tmp.str().data(), tmp.str().size());
+    }
+    ofilename = key;
+  }
+  fst->Write(filename_prefix + ofilename + filename_suffix);
+}
+
+template<class Arc>
+void FarExtract(const vector<string> &ifilenames,
+                const int32 &generate_filenames,
+                const string &keys,
+                const string &key_separator,
+                const string &range_delimiter,
+                const string &filename_prefix,
+                const string &filename_suffix) {
+  FarReader<Arc> *far_reader = FarReader<Arc>::Open(ifilenames);
+  if (!far_reader) return;
+
+  string okey;
+  int nrep = 0;
+
+  vector<char *> key_vector;
+  // User has specified a set of fsts to extract, where some of the "fsts" could
+  // be ranges.
+  if (!keys.empty()) {
+    char *keys_cstr = new char[keys.size()+1];
+    strcpy(keys_cstr, keys.c_str());
+    SplitToVector(keys_cstr, key_separator.c_str(), &key_vector, true);
+    int i = 0;
+    for (int k = 0; k < key_vector.size(); ++k, ++i) {
+      string key = string(key_vector[k]);
+      char *key_cstr = new char[key.size()+1];
+      strcpy(key_cstr, key.c_str());
+      vector<char *> range_vector;
+      SplitToVector(key_cstr, range_delimiter.c_str(), &range_vector, false);
+      if (range_vector.size() == 1) {  // Not a range
+        if (!far_reader->Find(key)) {
+          LOG(ERROR) << "FarExtract: Cannot find key: " << key;
+          return;
+        }
+        const Fst<Arc> &fst = far_reader->GetFst();
+        FarWriteFst(&fst, key, &okey, &nrep, generate_filenames, i,
+                    filename_prefix, filename_suffix);
+      } else if (range_vector.size() == 2) {  // A legal range
+        string begin_key = string(range_vector[0]);
+        string end_key = string(range_vector[1]);
+        if (begin_key.empty() || end_key.empty()) {
+          LOG(ERROR) << "FarExtract: Illegal range specification: " << key;
+          return;
+        }
+        if (!far_reader->Find(begin_key)) {
+          LOG(ERROR) << "FarExtract: Cannot find key: " << begin_key;
+          return;
+        }
+        for ( ; !far_reader->Done(); far_reader->Next(), ++i) {
+          string ikey = far_reader->GetKey();
+          if (end_key < ikey) break;
+          const Fst<Arc> &fst = far_reader->GetFst();
+          FarWriteFst(&fst, ikey, &okey, &nrep, generate_filenames, i,
+                      filename_prefix, filename_suffix);
+        }
+      } else {
+        LOG(ERROR) << "FarExtract: Illegal range specification: " << key;
+        return;
+      }
+      delete key_cstr;
+    }
+    delete keys_cstr;
+    return;
+  }
+  // Nothing specified: extract everything.
+  for (int i = 1; !far_reader->Done(); far_reader->Next(), ++i) {
+    string key = far_reader->GetKey();
+    const Fst<Arc> &fst = far_reader->GetFst();
+    FarWriteFst(&fst, key, &okey, &nrep, generate_filenames, i,
+                filename_prefix, filename_suffix);
+  }
+  return;
+}
+
+}  // namespace fst
+
+#endif  // FST_EXTENSIONS_FAR_EXTRACT_H__
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/far.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/far.h
new file mode 100644
index 0000000..acce76e
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/far.h
@@ -0,0 +1,532 @@
+// far.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: [email protected] (Michael Riley)
+//
+// \file
+// Finite-State Transducer (FST) archive classes.
+//
+
+#ifndef FST_EXTENSIONS_FAR_FAR_H__
+#define FST_EXTENSIONS_FAR_FAR_H__
+
+#include <fst/extensions/far/stlist.h>
+#include <fst/extensions/far/sttable.h>
+#include <fst/fst.h>
+#include <fst/vector-fst.h>
+
+namespace fst {
+
+enum FarEntryType { FET_LINE, FET_FILE };
+enum FarTokenType { FTT_SYMBOL, FTT_BYTE, FTT_UTF8 };
+
+inline bool IsFst(const string &filename) {
+  ifstream strm(filename.c_str());
+  if (!strm)
+    return false;
+  return IsFstHeader(strm, filename);
+}
+
+// FST archive header class
+class FarHeader {
+ public:
+  const string &FarType() const { return fartype_; }
+  const string &ArcType() const { return arctype_; }
+
+  bool Read(const string &filename) {
+    FstHeader fsthdr;
+    if (filename.empty()) {
+      // Header reading unsupported on stdin. Assumes STList and StdArc.
+      fartype_ = "stlist";
+      arctype_ = "standard";
+      return true;
+    } else if (IsSTTable(filename)) {  // Check if STTable
+      ReadSTTableHeader(filename, &fsthdr);
+      fartype_ = "sttable";
+      arctype_ = fsthdr.ArcType().empty() ? "unknown" : fsthdr.ArcType();
+      return true;
+    } else if (IsSTList(filename)) {  // Check if STList
+      ReadSTListHeader(filename, &fsthdr);
+      fartype_ = "sttable";
+      arctype_ = fsthdr.ArcType().empty() ? "unknown" : fsthdr.ArcType();
+      return true;
+    } else if (IsFst(filename)) {  // Check if Fst
+      ifstream istrm(filename.c_str());
+      fsthdr.Read(istrm, filename);
+      fartype_ = "fst";
+      arctype_ = fsthdr.ArcType().empty() ? "unknown" : fsthdr.ArcType();
+      return true;
+    }
+    return false;
+  }
+
+ private:
+  string fartype_;
+  string arctype_;
+};
+
+enum FarType {
+  FAR_DEFAULT = 0,
+  FAR_STTABLE = 1,
+  FAR_STLIST = 2,
+  FAR_FST = 3,
+};
+
+// This class creates an archive of FSTs.
+template <class A>
+class FarWriter {
+ public:
+  typedef A Arc;
+
+  // Creates a new (empty) FST archive; returns NULL on error.
+  static FarWriter *Create(const string &filename, FarType type = FAR_DEFAULT);
+
+  // Adds an FST to the end of an archive. Keys must be non-empty and
+  // in lexicographic order. FSTs must have a suitable write method.
+  virtual void Add(const string &key, const Fst<A> &fst) = 0;
+
+  virtual FarType Type() const = 0;
+
+  virtual bool Error() const = 0;
+
+  virtual ~FarWriter() {}
+
+ protected:
+  FarWriter() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(FarWriter);
+};
+
+
+// This class iterates through an existing archive of FSTs.
+template <class A>
+class FarReader {
+ public:
+ typedef A Arc;
+
+  // Opens an existing FST archive in a single file; returns NULL on error.
+  // Sets current position to the beginning of the achive.
+  static FarReader *Open(const string &filename);
+
+  // Opens an existing FST archive in multiple files; returns NULL on error.
+  // Sets current position to the beginning of the achive.
+  static FarReader *Open(const vector<string> &filenames);
+
+  // Resets current posision to beginning of archive.
+  virtual void Reset() = 0;
+
+  // Sets current position to first entry >= key.  Returns true if a match.
+  virtual bool Find(const string &key) = 0;
+
+  // Current position at end of archive?
+  virtual bool Done() const = 0;
+
+  // Move current position to next FST.
+  virtual void Next() = 0;
+
+  // Returns key at the current position. This reference is invalidated if
+  // the current position in the archive is changed.
+  virtual const string &GetKey() const = 0;
+
+  // Returns FST at the current position. This reference is invalidated if
+  // the current position in the archive is changed.
+  virtual const Fst<A> &GetFst() const = 0;
+
+  virtual FarType Type() const = 0;
+
+  virtual bool Error() const = 0;
+
+  virtual ~FarReader() {}
+
+ protected:
+  FarReader() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(FarReader);
+};
+
+
+template <class A>
+class FstWriter {
+ public:
+  void operator()(ostream &strm, const Fst<A> &fst) const {
+    fst.Write(strm, FstWriteOptions());
+  }
+};
+
+
+template <class A>
+class STTableFarWriter : public FarWriter<A> {
+ public:
+  typedef A Arc;
+
+  static STTableFarWriter *Create(const string &filename) {
+    STTableWriter<Fst<A>, FstWriter<A> > *writer =
+        STTableWriter<Fst<A>, FstWriter<A> >::Create(filename);
+    return new STTableFarWriter(writer);
+  }
+
+  void Add(const string &key, const Fst<A> &fst) { writer_->Add(key, fst); }
+
+  FarType Type() const { return FAR_STTABLE; }
+
+  bool Error() const { return writer_->Error(); }
+
+  ~STTableFarWriter() { delete writer_; }
+
+ private:
+  explicit STTableFarWriter(STTableWriter<Fst<A>, FstWriter<A> > *writer)
+      : writer_(writer) {}
+
+ private:
+  STTableWriter<Fst<A>, FstWriter<A> > *writer_;
+
+  DISALLOW_COPY_AND_ASSIGN(STTableFarWriter);
+};
+
+
+template <class A>
+class STListFarWriter : public FarWriter<A> {
+ public:
+  typedef A Arc;
+
+  static STListFarWriter *Create(const string &filename) {
+    STListWriter<Fst<A>, FstWriter<A> > *writer =
+        STListWriter<Fst<A>, FstWriter<A> >::Create(filename);
+    return new STListFarWriter(writer);
+  }
+
+  void Add(const string &key, const Fst<A> &fst) { writer_->Add(key, fst); }
+
+  FarType Type() const { return FAR_STLIST; }
+
+  bool Error() const { return writer_->Error(); }
+
+  ~STListFarWriter() { delete writer_; }
+
+ private:
+  explicit STListFarWriter(STListWriter<Fst<A>, FstWriter<A> > *writer)
+      : writer_(writer) {}
+
+ private:
+  STListWriter<Fst<A>, FstWriter<A> > *writer_;
+
+  DISALLOW_COPY_AND_ASSIGN(STListFarWriter);
+};
+
+
+template <class A>
+class FstFarWriter : public FarWriter<A> {
+ public:
+  typedef A Arc;
+
+  explicit FstFarWriter(const string &filename)
+      : filename_(filename), error_(false), written_(false) {}
+
+  static FstFarWriter *Create(const string &filename) {
+    return new FstFarWriter(filename);
+  }
+
+  void Add(const string &key, const Fst<A> &fst) {
+    if (written_) {
+      LOG(WARNING) << "FstFarWriter::Add: only one Fst supported,"
+                 << " subsequent entries discarded.";
+    } else {
+      error_ = !fst.Write(filename_);
+      written_ = true;
+    }
+  }
+
+  FarType Type() const { return FAR_FST; }
+
+  bool Error() const { return error_; }
+
+  ~FstFarWriter() {}
+
+ private:
+  string filename_;
+  bool error_;
+  bool written_;
+
+  DISALLOW_COPY_AND_ASSIGN(FstFarWriter);
+};
+
+
+template <class A>
+FarWriter<A> *FarWriter<A>::Create(const string &filename, FarType type) {
+  switch(type) {
+    case FAR_DEFAULT:
+      if (filename.empty())
+        return STListFarWriter<A>::Create(filename);
+    case FAR_STTABLE:
+      return STTableFarWriter<A>::Create(filename);
+      break;
+    case FAR_STLIST:
+      return STListFarWriter<A>::Create(filename);
+      break;
+    case FAR_FST:
+      return FstFarWriter<A>::Create(filename);
+      break;
+    default:
+      LOG(ERROR) << "FarWriter::Create: unknown far type";
+      return 0;
+  }
+}
+
+
+template <class A>
+class FstReader {
+ public:
+  Fst<A> *operator()(istream &strm) const {
+    return Fst<A>::Read(strm, FstReadOptions());
+  }
+};
+
+
+template <class A>
+class STTableFarReader : public FarReader<A> {
+ public:
+  typedef A Arc;
+
+  static STTableFarReader *Open(const string &filename) {
+    STTableReader<Fst<A>, FstReader<A> > *reader =
+        STTableReader<Fst<A>, FstReader<A> >::Open(filename);
+    // TODO: error check
+    return new STTableFarReader(reader);
+  }
+
+  static STTableFarReader *Open(const vector<string> &filenames) {
+    STTableReader<Fst<A>, FstReader<A> > *reader =
+        STTableReader<Fst<A>, FstReader<A> >::Open(filenames);
+    // TODO: error check
+    return new STTableFarReader(reader);
+  }
+
+  void Reset() { reader_->Reset(); }
+
+  bool Find(const string &key) { return reader_->Find(key); }
+
+  bool Done() const { return reader_->Done(); }
+
+  void Next() { return reader_->Next(); }
+
+  const string &GetKey() const { return reader_->GetKey(); }
+
+  const Fst<A> &GetFst() const { return reader_->GetEntry(); }
+
+  FarType Type() const { return FAR_STTABLE; }
+
+  bool Error() const { return reader_->Error(); }
+
+  ~STTableFarReader() { delete reader_; }
+
+ private:
+  explicit STTableFarReader(STTableReader<Fst<A>, FstReader<A> > *reader)
+      : reader_(reader) {}
+
+ private:
+  STTableReader<Fst<A>, FstReader<A> > *reader_;
+
+  DISALLOW_COPY_AND_ASSIGN(STTableFarReader);
+};
+
+
+template <class A>
+class STListFarReader : public FarReader<A> {
+ public:
+  typedef A Arc;
+
+  static STListFarReader *Open(const string &filename) {
+    STListReader<Fst<A>, FstReader<A> > *reader =
+        STListReader<Fst<A>, FstReader<A> >::Open(filename);
+    // TODO: error check
+    return new STListFarReader(reader);
+  }
+
+  static STListFarReader *Open(const vector<string> &filenames) {
+    STListReader<Fst<A>, FstReader<A> > *reader =
+        STListReader<Fst<A>, FstReader<A> >::Open(filenames);
+    // TODO: error check
+    return new STListFarReader(reader);
+  }
+
+  void Reset() { reader_->Reset(); }
+
+  bool Find(const string &key) { return reader_->Find(key); }
+
+  bool Done() const { return reader_->Done(); }
+
+  void Next() { return reader_->Next(); }
+
+  const string &GetKey() const { return reader_->GetKey(); }
+
+  const Fst<A> &GetFst() const { return reader_->GetEntry(); }
+
+  FarType Type() const { return FAR_STLIST; }
+
+  bool Error() const { return reader_->Error(); }
+
+  ~STListFarReader() { delete reader_; }
+
+ private:
+  explicit STListFarReader(STListReader<Fst<A>, FstReader<A> > *reader)
+      : reader_(reader) {}
+
+ private:
+  STListReader<Fst<A>, FstReader<A> > *reader_;
+
+  DISALLOW_COPY_AND_ASSIGN(STListFarReader);
+};
+
+template <class A>
+class FstFarReader : public FarReader<A> {
+ public:
+  typedef A Arc;
+
+  static FstFarReader *Open(const string &filename) {
+    vector<string> filenames;
+    filenames.push_back(filename);
+    return new FstFarReader<A>(filenames);
+  }
+
+  static FstFarReader *Open(const vector<string> &filenames) {
+    return new FstFarReader<A>(filenames);
+  }
+
+  FstFarReader(const vector<string> &filenames)
+      : keys_(filenames), has_stdin_(false), pos_(0), fst_(0), error_(false) {
+    sort(keys_.begin(), keys_.end());
+    streams_.resize(keys_.size(), 0);
+    for (size_t i = 0; i < keys_.size(); ++i) {
+      if (keys_[i].empty()) {
+        if (!has_stdin_) {
+          streams_[i] = &cin;
+          //sources_[i] = "stdin";
+          has_stdin_ = true;
+        } else {
+          FSTERROR() << "FstFarReader::FstFarReader: stdin should only "
+                     << "appear once in the input file list.";
+          error_ = true;
+          return;
+        }
+      } else {
+        streams_[i] = new ifstream(
+            keys_[i].c_str(), ifstream::in | ifstream::binary);
+      }
+    }
+    if (pos_ >= keys_.size()) return;
+    ReadFst();
+  }
+
+  void Reset() {
+    if (has_stdin_) {
+      FSTERROR() << "FstFarReader::Reset: operation not supported on stdin";
+      error_ = true;
+      return;
+    }
+    pos_ = 0;
+    ReadFst();
+  }
+
+  bool Find(const string &key) {
+    if (has_stdin_) {
+      FSTERROR() << "FstFarReader::Find: operation not supported on stdin";
+      error_ = true;
+      return false;
+    }
+    pos_ = 0;//TODO
+    ReadFst();
+    return true;
+  }
+
+  bool Done() const { return error_ || pos_ >= keys_.size(); }
+
+  void Next() {
+    ++pos_;
+    ReadFst();
+  }
+
+  const string &GetKey() const {
+    return keys_[pos_];
+  }
+
+  const Fst<A> &GetFst() const {
+    return *fst_;
+  }
+
+  FarType Type() const { return FAR_FST; }
+
+  bool Error() const { return error_; }
+
+  ~FstFarReader() {
+    if (fst_) delete fst_;
+    for (size_t i = 0; i < keys_.size(); ++i)
+      delete streams_[i];
+  }
+
+ private:
+  void ReadFst() {
+    if (fst_) delete fst_;
+    if (pos_ >= keys_.size()) return;
+    streams_[pos_]->seekg(0);
+    fst_ = Fst<A>::Read(*streams_[pos_], FstReadOptions());
+    if (!fst_) {
+      FSTERROR() << "FstFarReader: error reading Fst from: " << keys_[pos_];
+      error_ = true;
+    }
+  }
+
+ private:
+  vector<string> keys_;
+  vector<istream*> streams_;
+  bool has_stdin_;
+  size_t pos_;
+  mutable Fst<A> *fst_;
+  mutable bool error_;
+
+  DISALLOW_COPY_AND_ASSIGN(FstFarReader);
+};
+
+template <class A>
+FarReader<A> *FarReader<A>::Open(const string &filename) {
+  if (filename.empty())
+    return STListFarReader<A>::Open(filename);
+  else if (IsSTTable(filename))
+    return STTableFarReader<A>::Open(filename);
+  else if (IsSTList(filename))
+    return STListFarReader<A>::Open(filename);
+  else if (IsFst(filename))
+    return FstFarReader<A>::Open(filename);
+  return 0;
+}
+
+
+template <class A>
+FarReader<A> *FarReader<A>::Open(const vector<string> &filenames) {
+  if (!filenames.empty() && filenames[0].empty())
+    return STListFarReader<A>::Open(filenames);
+  else if (!filenames.empty() && IsSTTable(filenames[0]))
+    return STTableFarReader<A>::Open(filenames);
+  else if (!filenames.empty() && IsSTList(filenames[0]))
+    return STListFarReader<A>::Open(filenames);
+  else if (!filenames.empty() && IsFst(filenames[0]))
+    return FstFarReader<A>::Open(filenames);
+  return 0;
+}
+
+}  // namespace fst
+
+#endif  // FST_EXTENSIONS_FAR_FAR_H__
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/farlib.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/farlib.h
new file mode 100644
index 0000000..91ba224
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/farlib.h
@@ -0,0 +1,31 @@
+
+// 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: [email protected] (Jake Ratkiewicz)
+
+// A finite-state archive (FAR) is used to store an indexable collection of
+// FSTs in a single file. Utilities are provided to create FARs from FSTs,
+// to iterate over FARs, and to extract specific FSTs from FARs.
+
+#ifndef FST_EXTENSIONS_FAR_FARLIB_H_
+#define FST_EXTENSIONS_FAR_FARLIB_H_
+
+#include <fst/extensions/far/far.h>
+#include <fst/extensions/far/compile-strings.h>
+#include <fst/extensions/far/create.h>
+#include <fst/extensions/far/extract.h>
+#include <fst/extensions/far/info.h>
+#include <fst/extensions/far/print-strings.h>
+
+#endif  // FST_EXTENSIONS_FAR_FARLIB_H_
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/farscript.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/farscript.h
new file mode 100644
index 0000000..cfd9167
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/farscript.h
@@ -0,0 +1,273 @@
+
+// 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: [email protected] (Jake Ratkiewicz)
+
+// Convenience file for including all of the FAR operations,
+// or registering them for new arc types.
+
+#ifndef FST_EXTENSIONS_FAR_FARSCRIPT_H_
+#define FST_EXTENSIONS_FAR_FARSCRIPT_H_
+
+#include <vector>
+using std::vector;
+#include <string>
+
+#include <fst/script/arg-packs.h>
+#include <fst/extensions/far/compile-strings.h>
+#include <fst/extensions/far/create.h>
+#include <fst/extensions/far/equal.h>
+#include <fst/extensions/far/extract.h>
+#include <fst/extensions/far/info.h>
+#include <fst/extensions/far/print-strings.h>
+#include <fst/extensions/far/far.h>
+
+#include <fst/types.h>
+
+namespace fst {
+namespace script {
+
+// Note: it is safe to pass these strings as references because
+// this struct is only used to pass them deeper in the call graph.
+// Be sure you understand why this is so before using this struct
+// for anything else!
+struct FarCompileStringsArgs {
+  const vector<string> &in_fnames;
+  const string &out_fname;
+  const string &fst_type;
+  const FarType &far_type;
+  const int32 generate_keys;
+  const FarEntryType fet;
+  const FarTokenType tt;
+  const string &symbols_fname;
+  const string &unknown_symbol;
+  const bool keep_symbols;
+  const bool initial_symbols;
+  const bool allow_negative_labels;
+  const bool file_list_input;
+  const string &key_prefix;
+  const string &key_suffix;
+
+  FarCompileStringsArgs(const vector<string> &in_fnames,
+                        const string &out_fname,
+                        const string &fst_type,
+                        const FarType &far_type,
+                        int32 generate_keys,
+                        FarEntryType fet,
+                        FarTokenType tt,
+                        const string &symbols_fname,
+                        const string &unknown_symbol,
+                        bool keep_symbols,
+                        bool initial_symbols,
+                        bool allow_negative_labels,
+                        bool file_list_input,
+                        const string &key_prefix,
+                        const string &key_suffix) :
+      in_fnames(in_fnames), out_fname(out_fname), fst_type(fst_type),
+      far_type(far_type), generate_keys(generate_keys), fet(fet),
+      tt(tt), symbols_fname(symbols_fname), unknown_symbol(unknown_symbol),
+      keep_symbols(keep_symbols), initial_symbols(initial_symbols),
+      allow_negative_labels(allow_negative_labels),
+      file_list_input(file_list_input), key_prefix(key_prefix),
+      key_suffix(key_suffix) { }
+};
+
+template <class Arc>
+void FarCompileStrings(FarCompileStringsArgs *args) {
+  fst::FarCompileStrings<Arc>(
+      args->in_fnames, args->out_fname, args->fst_type, args->far_type,
+      args->generate_keys, args->fet, args->tt, args->symbols_fname,
+      args->unknown_symbol, args->keep_symbols, args->initial_symbols,
+      args->allow_negative_labels, args->file_list_input,
+      args->key_prefix, args->key_suffix);
+}
+
+void FarCompileStrings(
+    const vector<string> &in_fnames,
+    const string &out_fname,
+    const string &arc_type,
+    const string &fst_type,
+    const FarType &far_type,
+    int32 generate_keys,
+    FarEntryType fet,
+    FarTokenType tt,
+    const string &symbols_fname,
+    const string &unknown_symbol,
+    bool keep_symbols,
+    bool initial_symbols,
+    bool allow_negative_labels,
+    bool file_list_input,
+    const string &key_prefix,
+    const string &key_suffix);
+
+
+// Note: it is safe to pass these strings as references because
+// this struct is only used to pass them deeper in the call graph.
+// Be sure you understand why this is so before using this struct
+// for anything else!
+struct FarCreateArgs {
+  const vector<string> &in_fnames;
+  const string &out_fname;
+  const int32 generate_keys;
+  const bool file_list_input;
+  const FarType &far_type;
+  const string &key_prefix;
+  const string &key_suffix;
+
+  FarCreateArgs(
+      const vector<string> &in_fnames, const string &out_fname,
+      const int32 generate_keys, const bool file_list_input,
+      const FarType &far_type, const string &key_prefix,
+      const string &key_suffix)
+      : in_fnames(in_fnames), out_fname(out_fname),
+        generate_keys(generate_keys), file_list_input(file_list_input),
+        far_type(far_type), key_prefix(key_prefix), key_suffix(key_suffix) { }
+};
+
+template<class Arc>
+void FarCreate(FarCreateArgs *args) {
+  fst::FarCreate<Arc>(args->in_fnames, args->out_fname, args->generate_keys,
+                          args->file_list_input, args->far_type,
+                          args->key_prefix, args->key_suffix);
+}
+
+void FarCreate(const vector<string> &in_fnames,
+               const string &out_fname,
+               const string &arc_type,
+               const int32 generate_keys,
+               const bool file_list_input,
+               const FarType &far_type,
+               const string &key_prefix,
+               const string &key_suffix);
+
+
+typedef args::Package<const string &, const string &, float,
+                      const string &, const string &> FarEqualInnerArgs;
+typedef args::WithReturnValue<bool, FarEqualInnerArgs> FarEqualArgs;
+
+template <class Arc>
+void FarEqual(FarEqualArgs *args) {
+  args->retval = fst::FarEqual<Arc>(
+      args->args.arg1, args->args.arg2, args->args.arg3,
+      args->args.arg4, args->args.arg5);
+}
+
+bool FarEqual(const string &filename1,
+              const string &filename2,
+              const string &arc_type,
+              float delta = kDelta,
+              const string &begin_key = string(),
+              const string &end_key = string());
+
+
+typedef args::Package<const vector<string> &, int32,
+                      const string&, const string&, const string&,
+                      const string&, const string&> FarExtractArgs;
+
+template<class Arc>
+void FarExtract(FarExtractArgs *args) {
+  fst::FarExtract<Arc>(
+      args->arg1, args->arg2, args->arg3, args->arg4, args->arg5, args->arg6,
+      args->arg7);
+}
+
+void FarExtract(const vector<string> &ifilenames,
+                const string &arc_type,
+                int32 generate_filenames,
+                const string &keys,
+                const string &key_separator,
+                const string &range_delimiter,
+                const string &filename_prefix,
+                const string &filename_suffix);
+
+typedef args::Package<const vector<string> &, const string &,
+                      const string &, const bool> FarInfoArgs;
+
+template <class Arc>
+void FarInfo(FarInfoArgs *args) {
+  fst::FarInfo<Arc>(args->arg1, args->arg2, args->arg3, args->arg4);
+}
+
+void FarInfo(const vector<string> &filenames,
+             const string &arc_type,
+             const string &begin_key,
+             const string &end_key,
+             const bool list_fsts);
+
+struct FarPrintStringsArgs {
+  const vector<string> &ifilenames;
+  const FarEntryType entry_type;
+  const FarTokenType token_type;
+  const string &begin_key;
+  const string &end_key;
+  const bool print_key;
+  const bool print_weight;
+  const string &symbols_fname;
+  const bool initial_symbols;
+  const int32 generate_filenames;
+  const string &filename_prefix;
+  const string &filename_suffix;
+
+  FarPrintStringsArgs(
+      const vector<string> &ifilenames, const FarEntryType entry_type,
+      const FarTokenType token_type, const string &begin_key,
+      const string &end_key,  const bool print_key, const bool print_weight,
+      const string &symbols_fname, const bool initial_symbols,
+      const int32 generate_filenames,
+      const string &filename_prefix, const string &filename_suffix) :
+      ifilenames(ifilenames), entry_type(entry_type), token_type(token_type),
+      begin_key(begin_key), end_key(end_key),
+      print_key(print_key), print_weight(print_weight),
+      symbols_fname(symbols_fname), initial_symbols(initial_symbols),
+      generate_filenames(generate_filenames), filename_prefix(filename_prefix),
+      filename_suffix(filename_suffix) { }
+};
+
+template <class Arc>
+void FarPrintStrings(FarPrintStringsArgs *args) {
+  fst::FarPrintStrings<Arc>(
+      args->ifilenames, args->entry_type, args->token_type,
+      args->begin_key, args->end_key, args->print_key, args->print_weight,
+      args->symbols_fname, args->initial_symbols, args->generate_filenames,
+      args->filename_prefix, args->filename_suffix);
+}
+
+
+void FarPrintStrings(const vector<string> &ifilenames,
+                     const string &arc_type,
+                     const FarEntryType entry_type,
+                     const FarTokenType token_type,
+                     const string &begin_key,
+                     const string &end_key,
+                     const bool print_key,
+                     const bool print_weight,
+                     const string &symbols_fname,
+                     const bool initial_symbols,
+                     const int32 generate_filenames,
+                     const string &filename_prefix,
+                     const string &filename_suffix);
+
+}  // namespace script
+}  // namespace fst
+
+
+#define REGISTER_FST_FAR_OPERATIONS(ArcType)                            \
+  REGISTER_FST_OPERATION(FarCompileStrings, ArcType, FarCompileStringsArgs); \
+  REGISTER_FST_OPERATION(FarCreate, ArcType, FarCreateArgs);            \
+  REGISTER_FST_OPERATION(FarEqual, ArcType, FarEqualArgs);              \
+  REGISTER_FST_OPERATION(FarExtract, ArcType, FarExtractArgs);          \
+  REGISTER_FST_OPERATION(FarInfo, ArcType, FarInfoArgs);                \
+  REGISTER_FST_OPERATION(FarPrintStrings, ArcType, FarPrintStringsArgs)
+
+#endif  // FST_EXTENSIONS_FAR_FARSCRIPT_H_
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/info.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/info.h
new file mode 100644
index 0000000..100fe68
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/info.h
@@ -0,0 +1,128 @@
+
+// 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: [email protected] (Cyril Allauzen)
+// Modified: [email protected] (Jake Ratkiewicz)
+
+#ifndef FST_EXTENSIONS_FAR_INFO_H_
+#define FST_EXTENSIONS_FAR_INFO_H_
+
+#include <iomanip>
+#include <set>
+#include <string>
+#include <vector>
+using std::vector;
+
+#include <fst/extensions/far/far.h>
+#include <fst/extensions/far/main.h>  // For FarTypeToString
+
+namespace fst {
+
+template <class Arc>
+void CountStatesAndArcs(const Fst<Arc> &fst, size_t *nstate, size_t *narc) {
+  StateIterator<Fst<Arc> > siter(fst);
+  for (; !siter.Done(); siter.Next(), ++(*nstate)) {
+    ArcIterator<Fst<Arc> > aiter(fst, siter.Value());
+    for (; !aiter.Done(); aiter.Next(), ++(*narc)) {}
+  }
+}
+
+struct KeyInfo {
+  string key;
+  string type;
+  size_t nstate;
+  size_t narc;
+
+  KeyInfo(string k, string t, int64 ns = 0, int64 na = 0)
+  : key(k), type(t), nstate(ns), narc(na) {}
+};
+
+template <class Arc>
+void FarInfo(const vector<string> &filenames, const string &begin_key,
+             const string &end_key, const bool list_fsts) {
+  FarReader<Arc> *far_reader = FarReader<Arc>::Open(filenames);
+  if (!far_reader) return;
+
+  if (!begin_key.empty())
+    far_reader->Find(begin_key);
+
+  vector<KeyInfo> *infos = list_fsts ? new vector<KeyInfo>() : 0;
+  size_t nfst = 0, nstate = 0, narc = 0;
+  set<string> fst_types;
+  for (; !far_reader->Done(); far_reader->Next()) {
+    string key = far_reader->GetKey();
+    if (!end_key.empty() && end_key < key)
+      break;
+    ++nfst;
+    const Fst<Arc> &fst = far_reader->GetFst();
+    fst_types.insert(fst.Type());
+    if (infos) {
+      KeyInfo info(key, fst.Type());
+      CountStatesAndArcs(fst, &info.nstate, &info.narc);
+      nstate += info.nstate;
+      nstate += info.narc;
+      infos->push_back(info);
+    } else {
+      CountStatesAndArcs(fst, &nstate, &narc);
+    }
+  }
+
+  if (!infos) {
+    cout << std::left << setw(50) << "far type"
+         << FarTypeToString(far_reader->Type()) << endl;
+    cout << std::left << setw(50) << "arc type" << Arc::Type() << endl;
+    cout << std::left << setw(50) << "fst type";
+    for (set<string>::const_iterator iter = fst_types.begin();
+         iter != fst_types.end();
+         ++iter) {
+      if (iter != fst_types.begin())
+        cout << ",";
+      cout << *iter;
+    }
+    cout << endl;
+    cout << std::left << setw(50) << "# of FSTs" << nfst << endl;
+    cout << std::left << setw(50) << "total # of states" << nstate << endl;
+    cout << std::left << setw(50) << "total # of arcs" << narc << endl;
+
+  } else  {
+    int wkey = 10, wtype = 10, wnstate = 16, wnarc = 16;
+    for (size_t i = 0; i < infos->size(); ++i) {
+      const KeyInfo &info = (*infos)[i];
+      if (info.key.size() + 2 > wkey)
+        wkey = info.key.size() + 2;
+      if (info.type.size() + 2 > wtype)
+        wtype = info.type.size() + 2;
+      if (ceil(log10(info.nstate)) + 2 > wnstate)
+        wnstate = ceil(log10(info.nstate)) + 2;
+      if (ceil(log10(info.narc)) + 2 > wnarc)
+        wnarc = ceil(log10(info.narc)) + 2;
+    }
+
+    cout << std::left << setw(wkey) << "key" << setw(wtype) << "type"
+         << std::right << setw(wnstate) << "# of states"
+         << setw(wnarc) << "# of arcs" << endl;
+
+    for (size_t i = 0; i < infos->size(); ++i) {
+      const KeyInfo &info = (*infos)[i];
+      cout << std::left << setw(wkey) << info.key << setw(wtype) << info.type
+           << std::right << setw(wnstate) << info.nstate
+           << setw(wnarc) << info.narc << endl;
+    }
+  }
+}
+
+}  // namespace fst
+
+
+#endif  // FST_EXTENSIONS_FAR_INFO_H_
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/main.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/main.h
new file mode 100644
index 0000000..00ccfef
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/main.h
@@ -0,0 +1,43 @@
+// main.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: [email protected] (Michael Riley)
+//
+// \file
+// Classes and functions for registering and invoking Far main
+// functions that support multiple and extensible arc types.
+
+#ifndef FST_EXTENSIONS_FAR_MAIN_H__
+#define FST_EXTENSIONS_FAR_MAIN_H__
+
+#include <fst/extensions/far/far.h>
+
+namespace fst {
+
+FarEntryType StringToFarEntryType(const string &s);
+FarTokenType StringToFarTokenType(const string &s);
+
+// Return the 'FarType' value corresponding to a far type name.
+FarType FarTypeFromString(const string &str);
+
+// Return the textual name  corresponding to a 'FarType;.
+string FarTypeToString(FarType type);
+
+string LoadArcTypeFromFar(const string& far_fname);
+string LoadArcTypeFromFst(const string& far_fname);
+
+}  // namespace fst
+
+#endif  // FST_EXTENSIONS_FAR_MAIN_H__
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/print-strings.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/print-strings.h
new file mode 100644
index 0000000..dcc7351
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/print-strings.h
@@ -0,0 +1,138 @@
+// printstrings-main.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: [email protected] (Cyril Allauzen)
+// Modified by: [email protected] (Jake Ratkiewicz)
+//
+// \file
+// Output as strings the string FSTs in a finite-state archive.
+
+#ifndef FST_EXTENSIONS_FAR_PRINT_STRINGS_H__
+#define FST_EXTENSIONS_FAR_PRINT_STRINGS_H__
+
+#include <string>
+#include <vector>
+using std::vector;
+
+#include <fst/extensions/far/far.h>
+#include <fst/shortest-distance.h>
+#include <fst/string.h>
+
+DECLARE_string(far_field_separator);
+
+namespace fst {
+
+template <class Arc>
+void FarPrintStrings(
+    const vector<string> &ifilenames, const FarEntryType entry_type,
+    const FarTokenType far_token_type, const string &begin_key,
+    const string &end_key, const bool print_key, const bool print_weight,
+    const string &symbols_fname, const bool initial_symbols,
+    const int32 generate_filenames,
+    const string &filename_prefix, const string &filename_suffix) {
+
+  typename StringPrinter<Arc>::TokenType token_type;
+  if (far_token_type == FTT_SYMBOL) {
+    token_type = StringPrinter<Arc>::SYMBOL;
+  } else if (far_token_type == FTT_BYTE) {
+    token_type = StringPrinter<Arc>::BYTE;
+  } else if (far_token_type == FTT_UTF8) {
+    token_type = StringPrinter<Arc>::UTF8;
+  } else {
+    FSTERROR() << "FarPrintStrings: unknown token type";
+    return;
+  }
+
+  const SymbolTable *syms = 0;
+  if (!symbols_fname.empty()) {
+    // allow negative flag?
+    SymbolTableTextOptions opts;
+    opts.allow_negative = true;
+    syms = SymbolTable::ReadText(symbols_fname, opts);
+    if (!syms) {
+      FSTERROR() << "FarPrintStrings: error reading symbol table: "
+                 << symbols_fname;
+      return;
+    }
+  }
+
+  FarReader<Arc> *far_reader = FarReader<Arc>::Open(ifilenames);
+  if (!far_reader) return;
+
+  if (!begin_key.empty())
+    far_reader->Find(begin_key);
+
+  string okey;
+  int nrep = 0;
+  for (int i = 1; !far_reader->Done(); far_reader->Next(), ++i) {
+    string key = far_reader->GetKey();
+    if (!end_key.empty() && end_key < key)
+      break;
+    if (okey == key)
+      ++nrep;
+    else
+      nrep = 0;
+    okey = key;
+
+    const Fst<Arc> &fst = far_reader->GetFst();
+    if (i == 1 && initial_symbols && syms == 0 && fst.InputSymbols() != 0)
+      syms = fst.InputSymbols()->Copy();
+    string str;
+    VLOG(2) << "Handling key: " << key;
+    StringPrinter<Arc> string_printer(
+        token_type, syms ? syms : fst.InputSymbols());
+    string_printer(fst, &str);
+
+    if (entry_type == FET_LINE) {
+      if (print_key)
+        cout << key << FLAGS_far_field_separator[0];
+      cout << str;
+      if (print_weight)
+        cout << FLAGS_far_field_separator[0] << ShortestDistance(fst);
+      cout << endl;
+    } else if (entry_type == FET_FILE) {
+      stringstream sstrm;
+      if (generate_filenames) {
+        sstrm.fill('0');
+        sstrm << std::right << setw(generate_filenames) << i;
+      } else {
+        sstrm << key;
+        if (nrep > 0)
+          sstrm << "." << nrep;
+      }
+
+      string filename;
+      filename = filename_prefix +  sstrm.str() + filename_suffix;
+
+      ofstream ostrm(filename.c_str());
+      if (!ostrm) {
+        FSTERROR() << "FarPrintStrings: Can't open file:" << filename;
+        delete syms;
+        delete far_reader;
+        return;
+      }
+      ostrm << str;
+      if (token_type == StringPrinter<Arc>::SYMBOL)
+        ostrm << "\n";
+    }
+  }
+  delete syms;
+}
+
+
+
+}  // namespace fst
+
+#endif  // FST_EXTENSIONS_FAR_PRINT_STRINGS_H__
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/stlist.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/stlist.h
new file mode 100644
index 0000000..ff3d98b
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/stlist.h
@@ -0,0 +1,305 @@
+
+// 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: [email protected] (Cyril Allauzen)
+//
+// \file
+// A generic (string,type) list file format.
+//
+// This is a stripped-down version of STTable that does
+// not support the Find() operation but that does support
+// reading/writting from standard in/out.
+
+#ifndef FST_EXTENSIONS_FAR_STLIST_H_
+#define FST_EXTENSIONS_FAR_STLIST_H_
+
+#include <iostream>
+#include <fstream>
+#include <sstream>
+#include <fst/util.h>
+
+#include <algorithm>
+#include <functional>
+#include <queue>
+#include <string>
+#include <utility>
+using std::pair; using std::make_pair;
+#include <vector>
+using std::vector;
+
+namespace fst {
+
+static const int32 kSTListMagicNumber = 5656924;
+static const int32 kSTListFileVersion = 1;
+
+// String-type list writing class for object of type 'T' using functor 'W'
+// to write an object of type 'T' from a stream. 'W' must conform to the
+// following interface:
+//
+//   struct Writer {
+//     void operator()(ostream &, const T &) const;
+//   };
+//
+template <class T, class W>
+class STListWriter {
+ public:
+  typedef T EntryType;
+  typedef W EntryWriter;
+
+  explicit STListWriter(const string filename)
+      : stream_(
+          filename.empty() ? &cout :
+          new ofstream(filename.c_str(), ofstream::out | ofstream::binary)),
+        error_(false) {
+    WriteType(*stream_, kSTListMagicNumber);
+    WriteType(*stream_, kSTListFileVersion);
+    if (!stream_) {
+      FSTERROR() << "STListWriter::STListWriter: error writing to file: "
+                 << filename;
+      error_ = true;
+    }
+  }
+
+  static STListWriter<T, W> *Create(const string &filename) {
+    return new STListWriter<T, W>(filename);
+  }
+
+  void Add(const string &key, const T &t) {
+    if (key == "") {
+      FSTERROR() << "STListWriter::Add: key empty: " << key;
+      error_ = true;
+    } else if (key < last_key_) {
+      FSTERROR() << "STListWriter::Add: key disorder: " << key;
+      error_ = true;
+    }
+    if (error_) return;
+    last_key_ = key;
+    WriteType(*stream_, key);
+    entry_writer_(*stream_, t);
+  }
+
+  bool Error() const { return error_; }
+
+  ~STListWriter() {
+    WriteType(*stream_, string());
+    if (stream_ != &cout)
+      delete stream_;
+  }
+
+ private:
+  EntryWriter entry_writer_;  // Write functor for 'EntryType'
+  ostream *stream_;           // Output stream
+  string last_key_;           // Last key
+  bool error_;
+
+  DISALLOW_COPY_AND_ASSIGN(STListWriter);
+};
+
+
+// String-type list reading class for object of type 'T' using functor 'R'
+// to read an object of type 'T' form a stream. 'R' must conform to the
+// following interface:
+//
+//   struct Reader {
+//     T *operator()(istream &) const;
+//   };
+//
+template <class T, class R>
+class STListReader {
+ public:
+  typedef T EntryType;
+  typedef R EntryReader;
+
+  explicit STListReader(const vector<string> &filenames)
+      : sources_(filenames), entry_(0), error_(false) {
+    streams_.resize(filenames.size(), 0);
+    bool has_stdin = false;
+    for (size_t i = 0; i < filenames.size(); ++i) {
+      if (filenames[i].empty()) {
+        if (!has_stdin) {
+          streams_[i] = &cin;
+          sources_[i] = "stdin";
+          has_stdin = true;
+        } else {
+          FSTERROR() << "STListReader::STListReader: stdin should only "
+                     << "appear once in the input file list.";
+          error_ = true;
+          return;
+        }
+      } else {
+        streams_[i] = new ifstream(
+            filenames[i].c_str(), ifstream::in | ifstream::binary);
+      }
+      int32 magic_number = 0, file_version = 0;
+      ReadType(*streams_[i], &magic_number);
+      ReadType(*streams_[i], &file_version);
+      if (magic_number != kSTListMagicNumber) {
+        FSTERROR() << "STListReader::STListReader: wrong file type: "
+                   << filenames[i];
+        error_ = true;
+        return;
+      }
+      if (file_version != kSTListFileVersion) {
+        FSTERROR() << "STListReader::STListReader: wrong file version: "
+                   << filenames[i];
+        error_ = true;
+        return;
+      }
+      string key;
+      ReadType(*streams_[i], &key);
+      if (!key.empty())
+        heap_.push(make_pair(key, i));
+      if (!*streams_[i]) {
+        FSTERROR() << "STListReader: error reading file: " << sources_[i];
+        error_ = true;
+        return;
+      }
+    }
+    if (heap_.empty()) return;
+    size_t current = heap_.top().second;
+    entry_ = entry_reader_(*streams_[current]);
+    if (!entry_ || !*streams_[current]) {
+      FSTERROR() << "STListReader: error reading entry for key: "
+                 << heap_.top().first << ", file: " << sources_[current];
+      error_ = true;
+    }
+  }
+
+  ~STListReader() {
+    for (size_t i = 0; i < streams_.size(); ++i) {
+      if (streams_[i] != &cin)
+        delete streams_[i];
+    }
+    if (entry_)
+      delete entry_;
+  }
+
+  static STListReader<T, R> *Open(const string &filename) {
+    vector<string> filenames;
+    filenames.push_back(filename);
+    return new STListReader<T, R>(filenames);
+  }
+
+  static STListReader<T, R> *Open(const vector<string> &filenames) {
+    return new STListReader<T, R>(filenames);
+  }
+
+  void Reset() {
+    FSTERROR()
+        << "STListReader::Reset: stlist does not support reset operation";
+    error_ = true;
+  }
+
+  bool Find(const string &key) {
+    FSTERROR()
+        << "STListReader::Find: stlist does not support find operation";
+    error_ = true;
+    return false;
+  }
+
+  bool Done() const {
+    return error_ || heap_.empty();
+  }
+
+  void Next() {
+    if (error_) return;
+    size_t current = heap_.top().second;
+    string key;
+    heap_.pop();
+    ReadType(*(streams_[current]), &key);
+    if (!*streams_[current]) {
+      FSTERROR() << "STListReader: error reading file: "
+                 << sources_[current];
+      error_ = true;
+      return;
+    }
+    if (!key.empty())
+      heap_.push(make_pair(key, current));
+
+    if(!heap_.empty()) {
+      current = heap_.top().second;
+      if (entry_)
+        delete entry_;
+      entry_ = entry_reader_(*streams_[current]);
+      if (!entry_ || !*streams_[current]) {
+        FSTERROR() << "STListReader: error reading entry for key: "
+                   << heap_.top().first << ", file: " << sources_[current];
+        error_ = true;
+      }
+    }
+  }
+
+  const string &GetKey() const {
+    return heap_.top().first;
+  }
+
+  const EntryType &GetEntry() const {
+    return *entry_;
+  }
+
+  bool Error() const { return error_; }
+
+ private:
+  EntryReader entry_reader_;   // Read functor for 'EntryType'
+  vector<istream*> streams_;   // Input streams
+  vector<string> sources_;     // and corresponding file names
+  priority_queue<
+    pair<string, size_t>, vector<pair<string, size_t> >,
+    greater<pair<string, size_t> > > heap_;  // (Key, stream id) heap
+  mutable EntryType *entry_;   // Pointer to the currently read entry
+  bool error_;
+
+  DISALLOW_COPY_AND_ASSIGN(STListReader);
+};
+
+
+// String-type list header reading function template on the entry header
+// type 'H' having a member function:
+//   Read(istream &strm, const string &filename);
+// Checks that 'filename' is an STList and call the H::Read() on the last
+// entry in the STList.
+// Does not support reading from stdin.
+template <class H>
+bool ReadSTListHeader(const string &filename, H *header) {
+  if (filename.empty()) {
+    LOG(ERROR) << "ReadSTListHeader: reading header not supported on stdin";
+    return false;
+  }
+  ifstream strm(filename.c_str(), ifstream::in | ifstream::binary);
+  int32 magic_number = 0, file_version = 0;
+  ReadType(strm, &magic_number);
+  ReadType(strm, &file_version);
+  if (magic_number != kSTListMagicNumber) {
+    LOG(ERROR) << "ReadSTListHeader: wrong file type: " << filename;
+    return false;
+  }
+  if (file_version != kSTListFileVersion) {
+    LOG(ERROR) << "ReadSTListHeader: wrong file version: " << filename;
+    return false;
+  }
+  string key;
+  ReadType(strm, &key);
+  header->Read(strm, filename + ":" + key);
+  if (!strm) {
+    LOG(ERROR) << "ReadSTListHeader: error reading file: " << filename;
+    return false;
+  }
+  return true;
+}
+
+bool IsSTList(const string &filename);
+
+}  // namespace fst
+
+#endif  // FST_EXTENSIONS_FAR_STLIST_H_
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/far/sttable.h b/kaldi_io/src/tools/openfst/include/fst/extensions/far/sttable.h
new file mode 100644
index 0000000..3ce0a4b
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/far/sttable.h
@@ -0,0 +1,371 @@
+// sttable.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: [email protected] (Cyril Allauzen)
+//
+// \file
+// A generic string-to-type table file format
+//
+// This is not meant as a generalization of SSTable. This is more of
+// a simple replacement for SSTable in order to provide an open-source
+// implementation of the FAR format for the external version of the
+// FST Library.
+
+#ifndef FST_EXTENSIONS_FAR_STTABLE_H_
+#define FST_EXTENSIONS_FAR_STTABLE_H_
+
+#include <algorithm>
+#include <iostream>
+#include <fstream>
+#include <sstream>
+#include <fst/util.h>
+
+namespace fst {
+
+static const int32 kSTTableMagicNumber = 2125656924;
+static const int32 kSTTableFileVersion = 1;
+
+// String-to-type table writing class for object of type 'T' using functor 'W'
+// to write an object of type 'T' from a stream. 'W' must conform to the
+// following interface:
+//
+//   struct Writer {
+//     void operator()(ostream &, const T &) const;
+//   };
+//
+template <class T, class W>
+class STTableWriter {
+ public:
+  typedef T EntryType;
+  typedef W EntryWriter;
+
+  explicit STTableWriter(const string &filename)
+      : stream_(filename.c_str(), ofstream::out | ofstream::binary),
+        error_(false) {
+    WriteType(stream_, kSTTableMagicNumber);
+    WriteType(stream_, kSTTableFileVersion);
+    if (!stream_) {
+      FSTERROR() << "STTableWriter::STTableWriter: error writing to file: "
+                 << filename;
+      error_=true;
+    }
+  }
+
+  static STTableWriter<T, W> *Create(const string &filename) {
+    if (filename.empty()) {
+      LOG(ERROR) << "STTableWriter: writing to standard out unsupported.";
+      return 0;
+    }
+    return new STTableWriter<T, W>(filename);
+  }
+
+  void Add(const string &key, const T &t) {
+    if (key == "") {
+      FSTERROR() << "STTableWriter::Add: key empty: " << key;
+      error_ = true;
+    } else if (key < last_key_) {
+      FSTERROR() << "STTableWriter::Add: key disorder: " << key;
+      error_ = true;
+    }
+    if (error_) return;
+    last_key_ = key;
+    positions_.push_back(stream_.tellp());
+    WriteType(stream_, key);
+    entry_writer_(stream_, t);
+  }
+
+  bool Error() const { return error_; }
+
+  ~STTableWriter() {
+    WriteType(stream_, positions_);
+    WriteType(stream_, static_cast<int64>(positions_.size()));
+  }
+
+ private:
+  EntryWriter entry_writer_;  // Write functor for 'EntryType'
+  ofstream stream_;           // Output stream
+  vector<int64> positions_;   // Position in file of each key-entry pair
+  string last_key_;           // Last key
+  bool error_;
+
+  DISALLOW_COPY_AND_ASSIGN(STTableWriter);
+};
+
+
+// String-to-type table reading class for object of type 'T' using functor 'R'
+// to read an object of type 'T' form a stream. 'R' must conform to the
+// following interface:
+//
+//   struct Reader {
+//     T *operator()(istream &) const;
+//   };
+//
+template <class T, class R>
+class STTableReader {
+ public:
+  typedef T EntryType;
+  typedef R EntryReader;
+
+  explicit STTableReader(const vector<string> &filenames)
+      : sources_(filenames), entry_(0), error_(false) {
+    compare_ = new Compare(&keys_);
+    keys_.resize(filenames.size());
+    streams_.resize(filenames.size(), 0);
+    positions_.resize(filenames.size());
+    for (size_t i = 0; i < filenames.size(); ++i) {
+      streams_[i] = new ifstream(
+          filenames[i].c_str(), ifstream::in | ifstream::binary);
+      int32 magic_number = 0, file_version = 0;
+      ReadType(*streams_[i], &magic_number);
+      ReadType(*streams_[i], &file_version);
+      if (magic_number != kSTTableMagicNumber) {
+        FSTERROR() << "STTableReader::STTableReader: wrong file type: "
+                   << filenames[i];
+        error_ = true;
+        return;
+      }
+      if (file_version != kSTTableFileVersion) {
+        FSTERROR() << "STTableReader::STTableReader: wrong file version: "
+                   << filenames[i];
+        error_ = true;
+        return;
+      }
+      int64 num_entries;
+      streams_[i]->seekg(-static_cast<int>(sizeof(int64)), ios_base::end);
+      ReadType(*streams_[i], &num_entries);
+      streams_[i]->seekg(-static_cast<int>(sizeof(int64)) *
+                         (num_entries + 1), ios_base::end);
+      positions_[i].resize(num_entries);
+      for (size_t j = 0; (j < num_entries) && (*streams_[i]); ++j)
+        ReadType(*streams_[i], &(positions_[i][j]));
+      streams_[i]->seekg(positions_[i][0]);
+      if (!*streams_[i]) {
+        FSTERROR() << "STTableReader::STTableReader: error reading file: "
+                   << filenames[i];
+        error_ = true;
+        return;
+      }
+
+    }
+    MakeHeap();
+  }
+
+  ~STTableReader() {
+    for (size_t i = 0; i < streams_.size(); ++i)
+      delete streams_[i];
+    delete compare_;
+    if (entry_)
+      delete entry_;
+  }
+
+  static STTableReader<T, R> *Open(const string &filename) {
+    if (filename.empty()) {
+      LOG(ERROR) << "STTableReader: reading from standard in not supported";
+      return 0;
+    }
+    vector<string> filenames;
+    filenames.push_back(filename);
+    return new STTableReader<T, R>(filenames);
+  }
+
+  static STTableReader<T, R> *Open(const vector<string> &filenames) {
+    return new STTableReader<T, R>(filenames);
+  }
+
+  void Reset() {
+    if (error_) return;
+    for (size_t i = 0; i < streams_.size(); ++i)
+      streams_[i]->seekg(positions_[i].front());
+    MakeHeap();
+  }
+
+  bool Find(const string &key) {
+    if (error_) return false;
+    for (size_t i = 0; i < streams_.size(); ++i)
+      LowerBound(i, key);
+    MakeHeap();
+    return keys_[current_] == key;
+  }
+
+  bool Done() const { return error_ || heap_.empty(); }
+
+  void Next() {
+    if (error_) return;
+    if (streams_[current_]->tellg() <= positions_[current_].back()) {
+      ReadType(*(streams_[current_]), &(keys_[current_]));
+      if (!*streams_[current_]) {
+        FSTERROR() << "STTableReader: error reading file: "
+                   << sources_[current_];
+        error_ = true;
+        return;
+      }
+      push_heap(heap_.begin(), heap_.end(), *compare_);
+    } else {
+      heap_.pop_back();
+    }
+    if (!heap_.empty())
+      PopHeap();
+  }
+
+  const string &GetKey() const {
+    return keys_[current_];
+  }
+
+  const EntryType &GetEntry() const {
+    return *entry_;
+  }
+
+  bool Error() const { return error_; }
+
+ private:
+  // Comparison functor used to compare stream IDs in the heap
+  struct Compare {
+    Compare(const vector<string> *keys) : keys_(keys) {}
+
+    bool operator()(size_t i, size_t j) const {
+      return (*keys_)[i] > (*keys_)[j];
+    };
+
+   private:
+    const vector<string> *keys_;
+  };
+
+  // Position the stream with ID 'id' at the position corresponding
+  // to the lower bound for key 'find_key'
+  void LowerBound(size_t id, const string &find_key) {
+    ifstream *strm = streams_[id];
+    const vector<int64> &positions = positions_[id];
+    size_t low = 0, high = positions.size() - 1;
+
+    while (low < high) {
+      size_t mid = (low + high)/2;
+      strm->seekg(positions[mid]);
+      string key;
+      ReadType(*strm, &key);
+      if (key > find_key) {
+        high = mid;
+      } else if (key < find_key) {
+        low = mid + 1;
+      } else {
+        for (size_t i = mid; i > low; --i) {
+          strm->seekg(positions[i - 1]);
+          ReadType(*strm, &key);
+          if (key != find_key) {
+            strm->seekg(positions[i]);
+            return;
+          }
+        }
+        strm->seekg(positions[low]);
+        return;
+      }
+    }
+    strm->seekg(positions[low]);
+  }
+
+  // Add all streams to the heap
+  void MakeHeap() {
+    heap_.clear();
+    for (size_t i = 0; i < streams_.size(); ++i) {
+      ReadType(*streams_[i], &(keys_[i]));
+      if (!*streams_[i]) {
+        FSTERROR() << "STTableReader: error reading file: " << sources_[i];
+        error_ = true;
+        return;
+      }
+      heap_.push_back(i);
+    }
+    make_heap(heap_.begin(), heap_.end(), *compare_);
+    PopHeap();
+  }
+
+  // Position the stream with the lowest key at the top
+  // of the heap, set 'current_' to the ID of that stream
+  // and read the current entry from that stream
+  void PopHeap() {
+    pop_heap(heap_.begin(), heap_.end(), *compare_);
+    current_ = heap_.back();
+    if (entry_)
+      delete entry_;
+    entry_ = entry_reader_(*streams_[current_]);
+    if (!entry_)
+      error_ = true;
+    if (!*streams_[current_]) {
+      FSTERROR() << "STTableReader: error reading entry for key: "
+                 << keys_[current_] << ", file: " << sources_[current_];
+      error_ = true;
+    }
+  }
+
+
+  EntryReader entry_reader_;   // Read functor for 'EntryType'
+  vector<ifstream*> streams_;  // Input streams
+  vector<string> sources_;     // and corresponding file names
+  vector<vector<int64> > positions_;  // Index of positions for each stream
+  vector<string> keys_;  // Lowest unread key for each stream
+  vector<int64> heap_;   // Heap containing ID of streams with unread keys
+  int64 current_;        // Id of current stream to be read
+  Compare *compare_;     // Functor comparing stream IDs for the heap
+  mutable EntryType *entry_;  // Pointer to the currently read entry
+  bool error_;
+
+  DISALLOW_COPY_AND_ASSIGN(STTableReader);
+};
+
+
+// String-to-type table header reading function template on the entry header
+// type 'H' having a member function:
+//   Read(istream &strm, const string &filename);
+// Checks that 'filename' is an STTable and call the H::Read() on the last
+// entry in the STTable.
+template <class H>
+bool ReadSTTableHeader(const string &filename, H *header) {
+  ifstream strm(filename.c_str(), ifstream::in | ifstream::binary);
+  int32 magic_number = 0, file_version = 0;
+  ReadType(strm, &magic_number);
+  ReadType(strm, &file_version);
+  if (magic_number != kSTTableMagicNumber) {
+    LOG(ERROR) << "ReadSTTableHeader: wrong file type: " << filename;
+    return false;
+  }
+  if (file_version != kSTTableFileVersion) {
+    LOG(ERROR) << "ReadSTTableHeader: wrong file version: " << filename;
+    return false;
+  }
+  int64 i = -1;
+  strm.seekg(-static_cast<int>(sizeof(int64)), ios_base::end);
+  ReadType(strm, &i);  // Read number of entries
+  if (!strm) {
+    LOG(ERROR) << "ReadSTTableHeader: error reading file: " << filename;
+    return false;
+  }
+  if (i == 0) return true;  // No entry header to read
+  strm.seekg(-2 * static_cast<int>(sizeof(int64)), ios_base::end);
+  ReadType(strm, &i);  // Read position for last entry in file
+  strm.seekg(i);
+  string key;
+  ReadType(strm, &key);
+  header->Read(strm, filename + ":" + key);
+  if (!strm) {
+    LOG(ERROR) << "ReadSTTableHeader: error reading file: " << filename;
+    return false;
+  }
+  return true;
+}
+
+bool IsSTTable(const string &filename);
+
+}  // namespace fst
+
+#endif  // FST_EXTENSIONS_FAR_STTABLE_H_
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/bitmap-index.h b/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/bitmap-index.h
new file mode 100644
index 0000000..f5a5ba7
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/bitmap-index.h
@@ -0,0 +1,183 @@
+
+// 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: [email protected] (Jeffrey Sorensen)
+
+#ifndef FST_EXTENSIONS_NGRAM_BITMAP_INDEX_H_
+#define FST_EXTENSIONS_NGRAM_BITMAP_INDEX_H_
+
+#include <vector>
+using std::vector;
+
+#include <fst/compat.h>
+
+// This class is a bitstring storage class with an index that allows
+// seeking to the Nth set or clear bit in time O(Log(N)) where N is
+// the length of the bit vector.  In addition, it allows counting set or
+// clear bits over ranges in constant time.
+//
+// This is accomplished by maintaining an "secondary" index of limited
+// size in bits that maintains a running count of the number of bits set
+// in each block of bitmap data.  A block is defined as the number of
+// uint64 values that can fit in the secondary index before an overflow
+// occurs.
+//
+// To handle overflows, a "primary" index containing a running count of
+// bits set in each block is created using the type uint64.
+
+namespace fst {
+
+class BitmapIndex {
+ public:
+  static size_t StorageSize(size_t size) {
+    return ((size + kStorageBlockMask) >> kStorageLogBitSize);
+  }
+
+  BitmapIndex() : bits_(NULL), size_(0) { }
+
+  bool Get(size_t index) const {
+    return (bits_[index >> kStorageLogBitSize] &
+            (kOne << (index & kStorageBlockMask))) != 0;
+  }
+
+  static void Set(uint64* bits, size_t index) {
+    bits[index >> kStorageLogBitSize] |= (kOne << (index & kStorageBlockMask));
+  }
+
+  static void Clear(uint64* bits, size_t index) {
+    bits[index >> kStorageLogBitSize] &= ~(kOne << (index & kStorageBlockMask));
+  }
+
+  size_t Bits() const {
+    return size_;
+  }
+
+  size_t ArraySize() const {
+    return StorageSize(size_);
+  }
+
+  // Returns the number of one bits in the bitmap
+  size_t GetOnesCount() const {
+    return primary_index_[primary_index_size() - 1];
+  }
+
+  // Returns the number of one bits in positions 0 to limit - 1.
+  // REQUIRES: limit <= Bits()
+  size_t Rank1(size_t end) const;
+
+  // Returns the number of one bits in the range start to end - 1.
+  // REQUIRES: limit <= Bits()
+  size_t GetOnesCountInRange(size_t start, size_t end) const {
+    return Rank1(end) - Rank1(start);
+  }
+
+  // Returns the number of zero bits in positions 0 to limit - 1.
+  // REQUIRES: limit <= Bits()
+  size_t Rank0(size_t end) const {
+    return end - Rank1(end);
+  }
+
+  // Returns the number of zero bits in the range start to end - 1.
+  // REQUIRES: limit <= Bits()
+  size_t GetZeroesCountInRange(size_t start, size_t end) const {
+    return end - start - GetOnesCountInRange(start, end);
+  }
+
+  // Return true if any bit between begin inclusive and end exclusive
+  // is set.  0 <= begin <= end <= Bits() is required.
+  //
+  bool TestRange(size_t start, size_t end) const {
+    return Rank1(end) > Rank1(start);
+  }
+
+  // Returns the offset to the nth set bit (zero based)
+  // or Bits() if index >= number of ones
+  size_t Select1(size_t bit_index) const;
+
+  // Returns the offset to the nth clear bit (zero based)
+  // or Bits() if index > number of
+  size_t Select0(size_t bit_index) const;
+
+  // Rebuilds from index for the associated Bitmap, should be called
+  // whenever changes have been made to the Bitmap or else behavior
+  // of the indexed bitmap methods will be undefined.
+  void BuildIndex(const uint64 *bits, size_t size);
+
+  // the secondary index accumulates counts until it can possibly overflow
+  // this constant computes the number of uint64 units that can fit into
+  // units the size of uint16.
+  static const uint64 kOne = 1;
+  static const uint32 kStorageBitSize = 64;
+  static const uint32 kStorageLogBitSize = 6;
+  static const uint32 kSecondaryBlockSize = ((1 << 16) - 1)
+      >> kStorageLogBitSize;
+
+ private:
+  static const uint32 kStorageBlockMask = kStorageBitSize - 1;
+
+  // returns, from the index, the count of ones up to array_index
+  size_t get_index_ones_count(size_t array_index) const;
+
+  // because the indexes, both primary and secondary, contain a running
+  // count of the population of one bits contained in [0,i), there is
+  // no reason to have an element in the zeroth position as this value would
+  // necessarily be zero.  (The bits are indexed in a zero based way.)  Thus
+  // we don't store the 0th element in either index.  Both of the following
+  // functions, if greater than 0, must be decremented by one before retreiving
+  // the value from the corresponding array.
+  // returns the 1 + the block that contains the bitindex in question
+  // the inverted version works the same but looks for zeros using an inverted
+  // view of the index
+  size_t find_primary_block(size_t bit_index) const;
+
+  size_t find_inverted_primary_block(size_t bit_index) const;
+
+  // similarly, the secondary index (which resets its count to zero at
+  // the end of every kSecondaryBlockSize entries) does not store the element
+  // at 0.  Note that the rem_bit_index parameter is the number of bits
+  // within the secondary block, after the bits accounted for by the primary
+  // block have been removed (i.e. the remaining bits)  And, because we
+  // reset to zero with each new block, there is no need to store those
+  // actual zeros.
+  // returns 1 + the secondary block that contains the bitindex in question
+  size_t find_secondary_block(size_t block, size_t rem_bit_index) const;
+
+  size_t find_inverted_secondary_block(size_t block, size_t rem_bit_index)
+      const;
+
+  // We create a primary index based upon the number of secondary index
+  // blocks.  The primary index uses fields wide enough to accomodate any
+  // index of the bitarray so cannot overflow
+  // The primary index is the actual running
+  // count of one bits set for all blocks (and, thus, all uint64s).
+  size_t primary_index_size() const {
+    return (ArraySize() + kSecondaryBlockSize - 1) / kSecondaryBlockSize;
+  }
+
+  const uint64* bits_;
+  size_t size_;
+
+  // The primary index contains the running popcount of all blocks
+  // which means the nth value contains the popcounts of
+  // [0,n*kSecondaryBlockSize], however, the 0th element is omitted.
+  vector<uint32> primary_index_;
+  // The secondary index contains the running popcount of the associated
+  // bitmap.  It is the same length (in units of uint16) as the
+  // bitmap's map is in units of uint64s.
+  vector<uint16> secondary_index_;
+};
+
+}  // end namespace fst
+
+#endif  // FST_EXTENSIONS_NGRAM_BITMAP_INDEX_H_
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/ngram-fst.h b/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/ngram-fst.h
new file mode 100644
index 0000000..d113fb3
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/ngram-fst.h
@@ -0,0 +1,934 @@
+
+// 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: [email protected] (Jeffrey Sorensen)
+//
+#ifndef FST_EXTENSIONS_NGRAM_NGRAM_FST_H_
+#define FST_EXTENSIONS_NGRAM_NGRAM_FST_H_
+
+#include <stddef.h>
+#include <string.h>
+#include <algorithm>
+#include <string>
+#include <vector>
+using std::vector;
+
+#include <fst/compat.h>
+#include <fst/fstlib.h>
+#include <fst/mapped-file.h>
+#include <fst/extensions/ngram/bitmap-index.h>
+
+// NgramFst implements a n-gram language model based upon the LOUDS data
+// structure.  Please refer to "Unary Data Strucutres for Language Models"
+// http://research.google.com/pubs/archive/37218.pdf
+
+namespace fst {
+template <class A> class NGramFst;
+template <class A> class NGramFstMatcher;
+
+// Instance data containing mutable state for bookkeeping repeated access to
+// the same state.
+template <class A>
+struct NGramFstInst {
+  typedef typename A::Label Label;
+  typedef typename A::StateId StateId;
+  typedef typename A::Weight Weight;
+  StateId state_;
+  size_t num_futures_;
+  size_t offset_;
+  size_t node_;
+  StateId node_state_;
+  vector<Label> context_;
+  StateId context_state_;
+  NGramFstInst()
+      : state_(kNoStateId), node_state_(kNoStateId),
+        context_state_(kNoStateId) { }
+};
+
+// Implementation class for LOUDS based NgramFst interface
+template <class A>
+class NGramFstImpl : public FstImpl<A> {
+  using FstImpl<A>::SetInputSymbols;
+  using FstImpl<A>::SetOutputSymbols;
+  using FstImpl<A>::SetType;
+  using FstImpl<A>::WriteHeader;
+
+  friend class ArcIterator<NGramFst<A> >;
+  friend class NGramFstMatcher<A>;
+
+ public:
+  using FstImpl<A>::InputSymbols;
+  using FstImpl<A>::SetProperties;
+  using FstImpl<A>::Properties;
+
+  typedef A Arc;
+  typedef typename A::Label Label;
+  typedef typename A::StateId StateId;
+  typedef typename A::Weight Weight;
+
+  NGramFstImpl() : data_region_(0), data_(0), owned_(false) {
+    SetType("ngram");
+    SetInputSymbols(NULL);
+    SetOutputSymbols(NULL);
+    SetProperties(kStaticProperties);
+  }
+
+  NGramFstImpl(const Fst<A> &fst, vector<StateId>* order_out);
+
+  ~NGramFstImpl() {
+    if (owned_) {
+      delete [] data_;
+    }
+    delete data_region_;
+  }
+
+  static NGramFstImpl<A>* Read(istream &strm,  // NOLINT
+                               const FstReadOptions &opts) {
+    NGramFstImpl<A>* impl = new NGramFstImpl();
+    FstHeader hdr;
+    if (!impl->ReadHeader(strm, opts, kMinFileVersion, &hdr)) return 0;
+    uint64 num_states, num_futures, num_final;
+    const size_t offset = sizeof(num_states) + sizeof(num_futures) +
+        sizeof(num_final);
+    // Peek at num_states and num_futures to see how much more needs to be read.
+    strm.read(reinterpret_cast<char *>(&num_states), sizeof(num_states));
+    strm.read(reinterpret_cast<char *>(&num_futures), sizeof(num_futures));
+    strm.read(reinterpret_cast<char *>(&num_final), sizeof(num_final));
+    size_t size = Storage(num_states, num_futures, num_final);
+    MappedFile *data_region = MappedFile::Allocate(size);
+    char *data = reinterpret_cast<char *>(data_region->mutable_data());
+    // Copy num_states, num_futures and num_final back into data.
+    memcpy(data, reinterpret_cast<char *>(&num_states), sizeof(num_states));
+    memcpy(data + sizeof(num_states), reinterpret_cast<char *>(&num_futures),
+           sizeof(num_futures));
+    memcpy(data + sizeof(num_states) + sizeof(num_futures),
+           reinterpret_cast<char *>(&num_final), sizeof(num_final));
+    strm.read(data + offset, size - offset);
+    if (!strm) {
+      delete impl;
+      return NULL;
+    }
+    impl->Init(data, false, data_region);
+    return impl;
+  }
+
+  bool Write(ostream &strm,   // NOLINT
+             const FstWriteOptions &opts) const {
+    FstHeader hdr;
+    hdr.SetStart(Start());
+    hdr.SetNumStates(num_states_);
+    WriteHeader(strm, opts, kFileVersion, &hdr);
+    strm.write(data_, Storage(num_states_, num_futures_, num_final_));
+    return strm;
+  }
+
+  StateId Start() const {
+    return 1;
+  }
+
+  Weight Final(StateId state) const {
+    if (final_index_.Get(state)) {
+      return final_probs_[final_index_.Rank1(state)];
+    } else {
+      return Weight::Zero();
+    }
+  }
+
+  size_t NumArcs(StateId state, NGramFstInst<A> *inst = NULL) const {
+    if (inst == NULL) {
+      const size_t next_zero = future_index_.Select0(state + 1);
+      const size_t this_zero = future_index_.Select0(state);
+      return next_zero - this_zero - 1;
+    }
+    SetInstFuture(state, inst);
+    return inst->num_futures_ + ((state == 0) ? 0 : 1);
+  }
+
+  size_t NumInputEpsilons(StateId state) const {
+    // State 0 has no parent, thus no backoff.
+    if (state == 0) return 0;
+    return 1;
+  }
+
+  size_t NumOutputEpsilons(StateId state) const {
+    return NumInputEpsilons(state);
+  }
+
+  StateId NumStates() const {
+    return num_states_;
+  }
+
+  void InitStateIterator(StateIteratorData<A>* data) const {
+    data->base = 0;
+    data->nstates = num_states_;
+  }
+
+  static size_t Storage(uint64 num_states, uint64 num_futures,
+                        uint64 num_final) {
+    uint64 b64;
+    Weight weight;
+    Label label;
+    size_t offset = sizeof(num_states) + sizeof(num_futures) +
+        sizeof(num_final);
+    offset += sizeof(b64) * (
+        BitmapIndex::StorageSize(num_states * 2 + 1) +
+        BitmapIndex::StorageSize(num_futures + num_states + 1) +
+        BitmapIndex::StorageSize(num_states));
+    offset += (num_states + 1) * sizeof(label) + num_futures * sizeof(label);
+    // Pad for alignemnt, see
+    // http://en.wikipedia.org/wiki/Data_structure_alignment#Computing_padding
+    offset = (offset + sizeof(weight) - 1) & ~(sizeof(weight) - 1);
+    offset += (num_states + 1) * sizeof(weight) + num_final * sizeof(weight) +
+        (num_futures + 1) * sizeof(weight);
+    return offset;
+  }
+
+  void SetInstFuture(StateId state, NGramFstInst<A> *inst) const {
+    if (inst->state_ != state) {
+      inst->state_ = state;
+      const size_t next_zero = future_index_.Select0(state + 1);
+      const size_t this_zero = future_index_.Select0(state);
+      inst->num_futures_ = next_zero - this_zero - 1;
+      inst->offset_ = future_index_.Rank1(future_index_.Select0(state) + 1);
+    }
+  }
+
+  void SetInstNode(NGramFstInst<A> *inst) const {
+    if (inst->node_state_ != inst->state_) {
+      inst->node_state_ = inst->state_;
+      inst->node_ = context_index_.Select1(inst->state_);
+    }
+  }
+
+  void SetInstContext(NGramFstInst<A> *inst) const {
+    SetInstNode(inst);
+    if (inst->context_state_ != inst->state_) {
+      inst->context_state_ = inst->state_;
+      inst->context_.clear();
+      size_t node = inst->node_;
+      while (node != 0) {
+        inst->context_.push_back(context_words_[context_index_.Rank1(node)]);
+        node = context_index_.Select1(context_index_.Rank0(node) - 1);
+      }
+    }
+  }
+
+  // Access to the underlying representation
+  const char* GetData(size_t* data_size) const {
+    *data_size = Storage(num_states_, num_futures_, num_final_);
+    return data_;
+  }
+
+  void Init(const char* data, bool owned, MappedFile *file = 0);
+
+  const vector<Label> &GetContext(StateId s, NGramFstInst<A> *inst) const {
+    SetInstFuture(s, inst);
+    SetInstContext(inst);
+    return inst->context_;
+  }
+
+ private:
+  StateId Transition(const vector<Label> &context, Label future) const;
+
+  // Properties always true for this Fst class.
+  static const uint64 kStaticProperties = kAcceptor | kIDeterministic |
+      kODeterministic | kEpsilons | kIEpsilons | kOEpsilons | kILabelSorted |
+      kOLabelSorted | kWeighted | kCyclic | kInitialAcyclic | kNotTopSorted |
+      kAccessible | kCoAccessible | kNotString | kExpanded;
+  // Current file format version.
+  static const int kFileVersion = 4;
+  // Minimum file format version supported.
+  static const int kMinFileVersion = 4;
+
+  MappedFile *data_region_;
+  const char* data_;
+  bool owned_;  // True if we own data_
+  uint64 num_states_, num_futures_, num_final_;
+  size_t root_num_children_;
+  const Label *root_children_;
+  size_t root_first_child_;
+  // borrowed references
+  const uint64 *context_, *future_, *final_;
+  const Label *context_words_, *future_words_;
+  const Weight *backoff_, *final_probs_, *future_probs_;
+  BitmapIndex context_index_;
+  BitmapIndex future_index_;
+  BitmapIndex final_index_;
+
+  void operator=(const NGramFstImpl<A> &);  // Disallow
+};
+
+template<typename A>
+NGramFstImpl<A>::NGramFstImpl(const Fst<A> &fst, vector<StateId>* order_out)
+    : data_region_(0), data_(0), owned_(false) {
+  typedef A Arc;
+  typedef typename Arc::Label Label;
+  typedef typename Arc::Weight Weight;
+  typedef typename Arc::StateId StateId;
+  SetType("ngram");
+  SetInputSymbols(fst.InputSymbols());
+  SetOutputSymbols(fst.OutputSymbols());
+  SetProperties(kStaticProperties);
+
+  // Check basic requirements for an OpenGRM language model Fst.
+  int64 props = kAcceptor | kIDeterministic | kIEpsilons | kILabelSorted;
+  if (fst.Properties(props, true) != props) {
+    FSTERROR() << "NGramFst only accepts OpenGRM langauge models as input";
+    SetProperties(kError, kError);
+    return;
+  }
+
+  int64 num_states = CountStates(fst);
+  Label* context = new Label[num_states];
+
+  // Find the unigram state by starting from the start state, following
+  // epsilons.
+  StateId unigram = fst.Start();
+  while (1) {
+    if (unigram == kNoStateId) {
+      FSTERROR() << "Could not identify unigram state.";
+      SetProperties(kError, kError);
+      return;
+    }
+    ArcIterator<Fst<A> > aiter(fst, unigram);
+    if (aiter.Done()) {
+      LOG(WARNING) << "Unigram state " << unigram << " has no arcs.";
+      break;
+    }
+    if (aiter.Value().ilabel != 0) break;
+    unigram = aiter.Value().nextstate;
+  }
+
+  // Each state's context is determined by the subtree it is under from the
+  // unigram state.
+  queue<pair<StateId, Label> > label_queue;
+  vector<bool> visited(num_states);
+  // Force an epsilon link to the start state.
+  label_queue.push(make_pair(fst.Start(), 0));
+  for (ArcIterator<Fst<A> > aiter(fst, unigram);
+       !aiter.Done(); aiter.Next()) {
+    label_queue.push(make_pair(aiter.Value().nextstate, aiter.Value().ilabel));
+  }
+  // investigate states in breadth first fashion to assign context words.
+  while (!label_queue.empty()) {
+    pair<StateId, Label> &now = label_queue.front();
+    if (!visited[now.first]) {
+      context[now.first] = now.second;
+      visited[now.first] = true;
+      for (ArcIterator<Fst<A> > aiter(fst, now.first);
+           !aiter.Done(); aiter.Next()) {
+        const Arc &arc = aiter.Value();
+        if (arc.ilabel != 0) {
+          label_queue.push(make_pair(arc.nextstate, now.second));
+        }
+      }
+    }
+    label_queue.pop();
+  }
+  visited.clear();
+
+  // The arc from the start state should be assigned an epsilon to put it
+  // in front of the all other labels (which makes Start state 1 after
+  // unigram which is state 0).
+  context[fst.Start()] = 0;
+
+  // Build the tree of contexts fst by reversing the epsilon arcs from fst.
+  VectorFst<Arc> context_fst;
+  uint64 num_final = 0;
+  for (int i = 0; i < num_states; ++i) {
+    if (fst.Final(i) != Weight::Zero()) {
+      ++num_final;
+    }
+    context_fst.SetFinal(context_fst.AddState(), fst.Final(i));
+  }
+  context_fst.SetStart(unigram);
+  context_fst.SetInputSymbols(fst.InputSymbols());
+  context_fst.SetOutputSymbols(fst.OutputSymbols());
+  int64 num_context_arcs = 0;
+  int64 num_futures = 0;
+  for (StateIterator<Fst<A> > siter(fst); !siter.Done(); siter.Next()) {
+    const StateId &state = siter.Value();
+    num_futures += fst.NumArcs(state) - fst.NumInputEpsilons(state);
+    ArcIterator<Fst<A> > aiter(fst, state);
+    if (!aiter.Done()) {
+      const Arc &arc = aiter.Value();
+      // this arc goes from state to arc.nextstate, so create an arc from
+      // arc.nextstate to state to reverse it.
+      if (arc.ilabel == 0) {
+        context_fst.AddArc(arc.nextstate, Arc(context[state], context[state],
+                                              arc.weight, state));
+        num_context_arcs++;
+      }
+    }
+  }
+  if (num_context_arcs != context_fst.NumStates() - 1) {
+    FSTERROR() << "Number of contexts arcs != number of states - 1";
+    SetProperties(kError, kError);
+    return;
+  }
+  if (context_fst.NumStates() != num_states) {
+    FSTERROR() << "Number of contexts != number of states";
+    SetProperties(kError, kError);
+    return;
+  }
+  int64 context_props = context_fst.Properties(kIDeterministic |
+                                               kILabelSorted, true);
+  if (!(context_props & kIDeterministic)) {
+    FSTERROR() << "Input fst is not structured properly";
+    SetProperties(kError, kError);
+    return;
+  }
+  if (!(context_props & kILabelSorted)) {
+     ArcSort(&context_fst, ILabelCompare<Arc>());
+  }
+
+  delete [] context;
+
+  uint64 b64;
+  Weight weight;
+  Label label = kNoLabel;
+  const size_t storage = Storage(num_states, num_futures, num_final);
+  MappedFile *data_region = MappedFile::Allocate(storage);
+  char *data = reinterpret_cast<char *>(data_region->mutable_data());
+  memset(data, 0, storage);
+  size_t offset = 0;
+  memcpy(data + offset, reinterpret_cast<char *>(&num_states),
+         sizeof(num_states));
+  offset += sizeof(num_states);
+  memcpy(data + offset, reinterpret_cast<char *>(&num_futures),
+         sizeof(num_futures));
+  offset += sizeof(num_futures);
+  memcpy(data + offset, reinterpret_cast<char *>(&num_final),
+         sizeof(num_final));
+  offset += sizeof(num_final);
+  uint64* context_bits = reinterpret_cast<uint64*>(data + offset);
+  offset += BitmapIndex::StorageSize(num_states * 2 + 1) * sizeof(b64);
+  uint64* future_bits = reinterpret_cast<uint64*>(data + offset);
+  offset +=
+      BitmapIndex::StorageSize(num_futures + num_states + 1) * sizeof(b64);
+  uint64* final_bits = reinterpret_cast<uint64*>(data + offset);
+  offset += BitmapIndex::StorageSize(num_states) * sizeof(b64);
+  Label* context_words = reinterpret_cast<Label*>(data + offset);
+  offset += (num_states + 1) * sizeof(label);
+  Label* future_words = reinterpret_cast<Label*>(data + offset);
+  offset += num_futures * sizeof(label);
+  offset = (offset + sizeof(weight) - 1) & ~(sizeof(weight) - 1);
+  Weight* backoff = reinterpret_cast<Weight*>(data + offset);
+  offset += (num_states + 1) * sizeof(weight);
+  Weight* final_probs = reinterpret_cast<Weight*>(data + offset);
+  offset += num_final * sizeof(weight);
+  Weight* future_probs = reinterpret_cast<Weight*>(data + offset);
+  int64 context_arc = 0, future_arc = 0, context_bit = 0, future_bit = 0,
+        final_bit = 0;
+
+  // pseudo-root bits
+  BitmapIndex::Set(context_bits, context_bit++);
+  ++context_bit;
+  context_words[context_arc] = label;
+  backoff[context_arc] = Weight::Zero();
+  context_arc++;
+
+  ++future_bit;
+  if (order_out) {
+    order_out->clear();
+    order_out->resize(num_states);
+  }
+
+  queue<StateId> context_q;
+  context_q.push(context_fst.Start());
+  StateId state_number = 0;
+  while (!context_q.empty()) {
+    const StateId &state = context_q.front();
+    if (order_out) {
+      (*order_out)[state] = state_number;
+    }
+
+    const Weight &final = context_fst.Final(state);
+    if (final != Weight::Zero()) {
+      BitmapIndex::Set(final_bits, state_number);
+      final_probs[final_bit] = final;
+      ++final_bit;
+    }
+
+    for (ArcIterator<VectorFst<A> > aiter(context_fst, state);
+         !aiter.Done(); aiter.Next()) {
+      const Arc &arc = aiter.Value();
+      context_words[context_arc] = arc.ilabel;
+      backoff[context_arc] = arc.weight;
+      ++context_arc;
+      BitmapIndex::Set(context_bits, context_bit++);
+      context_q.push(arc.nextstate);
+    }
+    ++context_bit;
+
+    for (ArcIterator<Fst<A> > aiter(fst, state); !aiter.Done(); aiter.Next()) {
+      const Arc &arc = aiter.Value();
+      if (arc.ilabel != 0) {
+        future_words[future_arc] = arc.ilabel;
+        future_probs[future_arc] = arc.weight;
+        ++future_arc;
+        BitmapIndex::Set(future_bits, future_bit++);
+      }
+    }
+    ++future_bit;
+    ++state_number;
+    context_q.pop();
+  }
+
+  if ((state_number !=  num_states) ||
+      (context_bit != num_states * 2 + 1) ||
+      (context_arc != num_states) ||
+      (future_arc != num_futures) ||
+      (future_bit != num_futures + num_states + 1) ||
+      (final_bit != num_final)) {
+    FSTERROR() << "Structure problems detected during construction";
+    SetProperties(kError, kError);
+    return;
+  }
+
+  Init(data, false, data_region);
+}
+
+template<typename A>
+inline void NGramFstImpl<A>::Init(const char* data, bool owned,
+                                  MappedFile *data_region) {
+  if (owned_) {
+    delete [] data_;
+  }
+  delete data_region_;
+  data_region_ = data_region;
+  owned_ = owned;
+  data_ = data;
+  size_t offset = 0;
+  num_states_ = *(reinterpret_cast<const uint64*>(data_ + offset));
+  offset += sizeof(num_states_);
+  num_futures_ = *(reinterpret_cast<const uint64*>(data_ + offset));
+  offset += sizeof(num_futures_);
+  num_final_ = *(reinterpret_cast<const uint64*>(data_ + offset));
+  offset += sizeof(num_final_);
+  uint64 bits;
+  size_t context_bits = num_states_ * 2 + 1;
+  size_t future_bits = num_futures_ + num_states_ + 1;
+  context_ = reinterpret_cast<const uint64*>(data_ + offset);
+  offset += BitmapIndex::StorageSize(context_bits) * sizeof(bits);
+  future_ = reinterpret_cast<const uint64*>(data_ + offset);
+  offset += BitmapIndex::StorageSize(future_bits) * sizeof(bits);
+  final_ = reinterpret_cast<const uint64*>(data_ + offset);
+  offset += BitmapIndex::StorageSize(num_states_) * sizeof(bits);
+  context_words_ = reinterpret_cast<const Label*>(data_ + offset);
+  offset += (num_states_ + 1) * sizeof(*context_words_);
+  future_words_ = reinterpret_cast<const Label*>(data_ + offset);
+  offset += num_futures_ * sizeof(*future_words_);
+  offset = (offset + sizeof(*backoff_) - 1) & ~(sizeof(*backoff_) - 1);
+  backoff_ = reinterpret_cast<const Weight*>(data_ + offset);
+  offset += (num_states_ + 1) * sizeof(*backoff_);
+  final_probs_ = reinterpret_cast<const Weight*>(data_ + offset);
+  offset += num_final_ * sizeof(*final_probs_);
+  future_probs_ = reinterpret_cast<const Weight*>(data_ + offset);
+
+  context_index_.BuildIndex(context_, context_bits);
+  future_index_.BuildIndex(future_, future_bits);
+  final_index_.BuildIndex(final_, num_states_);
+
+  const size_t node_rank = context_index_.Rank1(0);
+  root_first_child_ = context_index_.Select0(node_rank) + 1;
+  if (context_index_.Get(root_first_child_) == false) {
+    FSTERROR() << "Missing unigrams";
+    SetProperties(kError, kError);
+    return;
+  }
+  const size_t last_child = context_index_.Select0(node_rank + 1) - 1;
+  root_num_children_ = last_child - root_first_child_ + 1;
+  root_children_ = context_words_ + context_index_.Rank1(root_first_child_);
+}
+
+template<typename A>
+inline typename A::StateId NGramFstImpl<A>::Transition(
+        const vector<Label> &context, Label future) const {
+  size_t num_children = root_num_children_;
+  const Label *children = root_children_;
+  const Label *loc = lower_bound(children, children + num_children, future);
+  if (loc == children + num_children || *loc != future) {
+    return context_index_.Rank1(0);
+  }
+  size_t node = root_first_child_ + loc - children;
+  size_t node_rank = context_index_.Rank1(node);
+  size_t first_child = context_index_.Select0(node_rank) + 1;
+  if (context_index_.Get(first_child) == false) {
+    return context_index_.Rank1(node);
+  }
+  size_t last_child = context_index_.Select0(node_rank + 1) - 1;
+  num_children = last_child - first_child + 1;
+  for (int word = context.size() - 1; word >= 0; --word) {
+    children = context_words_ + context_index_.Rank1(first_child);
+    loc = lower_bound(children, children + last_child - first_child + 1,
+                      context[word]);
+    if (loc == children + last_child - first_child + 1 ||
+        *loc != context[word]) {
+      break;
+    }
+    node = first_child + loc - children;
+    node_rank = context_index_.Rank1(node);
+    first_child = context_index_.Select0(node_rank) + 1;
+    if (context_index_.Get(first_child) == false) break;
+    last_child = context_index_.Select0(node_rank + 1) - 1;
+  }
+  return context_index_.Rank1(node);
+}
+
+/*****************************************************************************/
+template<class A>
+class NGramFst : public ImplToExpandedFst<NGramFstImpl<A> > {
+  friend class ArcIterator<NGramFst<A> >;
+  friend class NGramFstMatcher<A>;
+
+ public:
+  typedef A Arc;
+  typedef typename A::StateId StateId;
+  typedef typename A::Label Label;
+  typedef typename A::Weight Weight;
+  typedef NGramFstImpl<A> Impl;
+
+  explicit NGramFst(const Fst<A> &dst)
+      : ImplToExpandedFst<Impl>(new Impl(dst, NULL)) {}
+
+  NGramFst(const Fst<A> &fst, vector<StateId>* order_out)
+      : ImplToExpandedFst<Impl>(new Impl(fst, order_out)) {}
+
+  // Because the NGramFstImpl is a const stateless data structure, there
+  // is never a need to do anything beside copy the reference.
+  NGramFst(const NGramFst<A> &fst, bool safe = false)
+      : ImplToExpandedFst<Impl>(fst, false) {}
+
+  NGramFst() : ImplToExpandedFst<Impl>(new Impl()) {}
+
+  // Non-standard constructor to initialize NGramFst directly from data.
+  NGramFst(const char* data, bool owned) : ImplToExpandedFst<Impl>(new Impl()) {
+    GetImpl()->Init(data, owned, NULL);
+  }
+
+  // Get method that gets the data associated with Init().
+  const char* GetData(size_t* data_size) const {
+    return GetImpl()->GetData(data_size);
+  }
+
+  const vector<Label> GetContext(StateId s) const {
+    return GetImpl()->GetContext(s, &inst_);
+  }
+
+  virtual size_t NumArcs(StateId s) const {
+    return GetImpl()->NumArcs(s, &inst_);
+  }
+
+  virtual NGramFst<A>* Copy(bool safe = false) const {
+    return new NGramFst(*this, safe);
+  }
+
+  static NGramFst<A>* Read(istream &strm, const FstReadOptions &opts) {
+    Impl* impl = Impl::Read(strm, opts);
+    return impl ? new NGramFst<A>(impl) : 0;
+  }
+
+  static NGramFst<A>* Read(const string &filename) {
+    if (!filename.empty()) {
+      ifstream strm(filename.c_str(), ifstream::in | ifstream::binary);
+      if (!strm) {
+        LOG(ERROR) << "NGramFst::Read: Can't open file: " << filename;
+        return 0;
+      }
+      return Read(strm, FstReadOptions(filename));
+    } else {
+      return Read(cin, FstReadOptions("standard input"));
+    }
+  }
+
+  virtual bool Write(ostream &strm, const FstWriteOptions &opts) const {
+    return GetImpl()->Write(strm, opts);
+  }
+
+  virtual bool Write(const string &filename) const {
+    return Fst<A>::WriteFile(filename);
+  }
+
+  virtual inline void InitStateIterator(StateIteratorData<A>* data) const {
+    GetImpl()->InitStateIterator(data);
+  }
+
+  virtual inline void InitArcIterator(
+      StateId s, ArcIteratorData<A>* data) const;
+
+  virtual MatcherBase<A>* InitMatcher(MatchType match_type) const {
+    return new NGramFstMatcher<A>(*this, match_type);
+  }
+
+ private:
+  explicit NGramFst(Impl* impl) : ImplToExpandedFst<Impl>(impl) {}
+
+  Impl* GetImpl() const {
+    return
+        ImplToExpandedFst<Impl, ExpandedFst<A> >::GetImpl();
+  }
+
+  void SetImpl(Impl* impl, bool own_impl = true) {
+    ImplToExpandedFst<Impl, Fst<A> >::SetImpl(impl, own_impl);
+  }
+
+  mutable NGramFstInst<A> inst_;
+};
+
+template <class A> inline void
+NGramFst<A>::InitArcIterator(StateId s, ArcIteratorData<A>* data) const {
+  GetImpl()->SetInstFuture(s, &inst_);
+  GetImpl()->SetInstNode(&inst_);
+  data->base = new ArcIterator<NGramFst<A> >(*this, s);
+}
+
+/*****************************************************************************/
+template <class A>
+class NGramFstMatcher : public MatcherBase<A> {
+ public:
+  typedef A Arc;
+  typedef typename A::Label Label;
+  typedef typename A::StateId StateId;
+  typedef typename A::Weight Weight;
+
+  NGramFstMatcher(const NGramFst<A> &fst, MatchType match_type)
+      : fst_(fst), inst_(fst.inst_), match_type_(match_type),
+        current_loop_(false),
+        loop_(kNoLabel, 0, A::Weight::One(), kNoStateId) {
+    if (match_type_ == MATCH_OUTPUT) {
+      swap(loop_.ilabel, loop_.olabel);
+    }
+  }
+
+  NGramFstMatcher(const NGramFstMatcher<A> &matcher, bool safe = false)
+      : fst_(matcher.fst_), inst_(matcher.inst_),
+        match_type_(matcher.match_type_), current_loop_(false),
+        loop_(kNoLabel, 0, A::Weight::One(), kNoStateId) {
+    if (match_type_ == MATCH_OUTPUT) {
+      swap(loop_.ilabel, loop_.olabel);
+    }
+  }
+
+  virtual NGramFstMatcher<A>* Copy(bool safe = false) const {
+    return new NGramFstMatcher<A>(*this, safe);
+  }
+
+  virtual MatchType Type(bool test) const {
+    return match_type_;
+  }
+
+  virtual const Fst<A> &GetFst() const {
+    return fst_;
+  }
+
+  virtual uint64 Properties(uint64 props) const {
+    return props;
+  }
+
+ private:
+  virtual void SetState_(StateId s) {
+    fst_.GetImpl()->SetInstFuture(s, &inst_);
+    current_loop_ = false;
+  }
+
+  virtual bool Find_(Label label) {
+    const Label nolabel = kNoLabel;
+    done_ = true;
+    if (label == 0 || label == nolabel) {
+      if (label == 0) {
+        current_loop_ = true;
+        loop_.nextstate = inst_.state_;
+      }
+      // The unigram state has no epsilon arc.
+      if (inst_.state_ != 0) {
+        arc_.ilabel = arc_.olabel = 0;
+        fst_.GetImpl()->SetInstNode(&inst_);
+        arc_.nextstate = fst_.GetImpl()->context_index_.Rank1(
+            fst_.GetImpl()->context_index_.Select1(
+                fst_.GetImpl()->context_index_.Rank0(inst_.node_) - 1));
+        arc_.weight = fst_.GetImpl()->backoff_[inst_.state_];
+        done_ = false;
+      }
+    } else {
+      const Label *start = fst_.GetImpl()->future_words_ + inst_.offset_;
+      const Label *end = start + inst_.num_futures_;
+      const Label* search = lower_bound(start, end, label);
+      if (search != end && *search == label) {
+        size_t state = search - start;
+        arc_.ilabel = arc_.olabel = label;
+        arc_.weight = fst_.GetImpl()->future_probs_[inst_.offset_ + state];
+        fst_.GetImpl()->SetInstContext(&inst_);
+        arc_.nextstate = fst_.GetImpl()->Transition(inst_.context_, label);
+        done_ = false;
+      }
+    }
+    return !Done_();
+  }
+
+  virtual bool Done_() const {
+    return !current_loop_ && done_;
+  }
+
+  virtual const Arc& Value_() const {
+    return (current_loop_) ? loop_ : arc_;
+  }
+
+  virtual void Next_() {
+    if (current_loop_) {
+      current_loop_ = false;
+    } else {
+      done_ = true;
+    }
+  }
+
+  const NGramFst<A>& fst_;
+  NGramFstInst<A> inst_;
+  MatchType match_type_;             // Supplied by caller
+  bool done_;
+  Arc arc_;
+  bool current_loop_;                // Current arc is the implicit loop
+  Arc loop_;
+};
+
+/*****************************************************************************/
+template<class A>
+class ArcIterator<NGramFst<A> > : public ArcIteratorBase<A> {
+ public:
+  typedef A Arc;
+  typedef typename A::Label Label;
+  typedef typename A::StateId StateId;
+  typedef typename A::Weight Weight;
+
+  ArcIterator(const NGramFst<A> &fst, StateId state)
+      : lazy_(~0), impl_(fst.GetImpl()), i_(0), flags_(kArcValueFlags) {
+    inst_ = fst.inst_;
+    impl_->SetInstFuture(state, &inst_);
+    impl_->SetInstNode(&inst_);
+  }
+
+  bool Done() const {
+    return i_ >= ((inst_.node_ == 0) ? inst_.num_futures_ :
+                  inst_.num_futures_ + 1);
+  }
+
+  const Arc &Value() const {
+    bool eps = (inst_.node_ != 0 && i_ == 0);
+    StateId state = (inst_.node_ == 0) ? i_ : i_ - 1;
+    if (flags_ & lazy_ & (kArcILabelValue | kArcOLabelValue)) {
+      arc_.ilabel =
+          arc_.olabel = eps ? 0 : impl_->future_words_[inst_.offset_ + state];
+      lazy_ &= ~(kArcILabelValue | kArcOLabelValue);
+    }
+    if (flags_ & lazy_ & kArcNextStateValue) {
+      if (eps) {
+        arc_.nextstate = impl_->context_index_.Rank1(
+            impl_->context_index_.Select1(
+                impl_->context_index_.Rank0(inst_.node_) - 1));
+      } else {
+        if (lazy_ & kArcNextStateValue) {
+          impl_->SetInstContext(&inst_);  // first time only.
+        }
+        arc_.nextstate =
+            impl_->Transition(inst_.context_,
+                              impl_->future_words_[inst_.offset_ + state]);
+      }
+      lazy_ &= ~kArcNextStateValue;
+    }
+    if (flags_ & lazy_ & kArcWeightValue) {
+      arc_.weight = eps ?  impl_->backoff_[inst_.state_] :
+          impl_->future_probs_[inst_.offset_ + state];
+      lazy_ &= ~kArcWeightValue;
+    }
+    return arc_;
+  }
+
+  void Next() {
+    ++i_;
+    lazy_ = ~0;
+  }
+
+  size_t Position() const { return i_; }
+
+  void Reset() {
+    i_ = 0;
+    lazy_ = ~0;
+  }
+
+  void Seek(size_t a) {
+    if (i_ != a) {
+      i_ = a;
+      lazy_ = ~0;
+    }
+  }
+
+  uint32 Flags() const {
+    return flags_;
+  }
+
+  void SetFlags(uint32 f, uint32 m) {
+    flags_ &= ~m;
+    flags_ |= (f & kArcValueFlags);
+  }
+
+ private:
+  virtual bool Done_() const { return Done(); }
+  virtual const Arc& Value_() const { return Value(); }
+  virtual void Next_() { Next(); }
+  virtual size_t Position_() const { return Position(); }
+  virtual void Reset_() { Reset(); }
+  virtual void Seek_(size_t a) { Seek(a); }
+  uint32 Flags_() const { return Flags(); }
+  void SetFlags_(uint32 f, uint32 m) { SetFlags(f, m); }
+
+  mutable Arc arc_;
+  mutable uint32 lazy_;
+  const NGramFstImpl<A> *impl_;
+  mutable NGramFstInst<A> inst_;
+
+  size_t i_;
+  uint32 flags_;
+
+  DISALLOW_COPY_AND_ASSIGN(ArcIterator);
+};
+
+/*****************************************************************************/
+// Specialization for NGramFst; see generic version in fst.h
+// for sample usage (but use the ProdLmFst type!). This version
+// should inline.
+template <class A>
+class StateIterator<NGramFst<A> > : public StateIteratorBase<A> {
+  public:
+  typedef typename A::StateId StateId;
+
+  explicit StateIterator(const NGramFst<A> &fst)
+    : s_(0), num_states_(fst.NumStates()) { }
+
+  bool Done() const { return s_ >= num_states_; }
+  StateId Value() const { return s_; }
+  void Next() { ++s_; }
+  void Reset() { s_ = 0; }
+
+ private:
+  virtual bool Done_() const { return Done(); }
+  virtual StateId Value_() const { return Value(); }
+  virtual void Next_() { Next(); }
+  virtual void Reset_() { Reset(); }
+
+  StateId s_, num_states_;
+
+  DISALLOW_COPY_AND_ASSIGN(StateIterator);
+};
+}  // namespace fst
+#endif  // FST_EXTENSIONS_NGRAM_NGRAM_FST_H_
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/nthbit.h b/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/nthbit.h
new file mode 100644
index 0000000..d4a9a5a
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/nthbit.h
@@ -0,0 +1,46 @@
+
+// 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: [email protected] (Jeffrey Sorensen)
+//         [email protected] (Doug Rohde)
+
+#ifndef FST_EXTENSIONS_NGRAM_NTHBIT_H_
+#define FST_EXTENSIONS_NGRAM_NTHBIT_H_
+
+#include <fst/types.h>
+
+extern uint32 nth_bit_bit_offset[];
+
+inline uint32 nth_bit(uint64 v, uint32 r) {
+  uint32 shift = 0;
+  uint32 c = __builtin_popcount(v & 0xffffffff);
+  uint32 mask = -(r > c);
+  r -= c & mask;
+  shift += (32 & mask);
+
+  c = __builtin_popcount((v >> shift) & 0xffff);
+  mask = -(r > c);
+  r -= c & mask;
+  shift += (16 & mask);
+
+  c = __builtin_popcount((v >> shift) & 0xff);
+  mask = -(r > c);
+  r -= c & mask;
+  shift += (8 & mask);
+
+  return shift + ((nth_bit_bit_offset[(v >> shift) & 0xff] >>
+                   ((r - 1) << 2)) & 0xf);
+}
+
+#endif  // FST_EXTENSIONS_NGRAM_NTHBIT_H_