add decodable & ctc_beam_search_deocder

speechx/speechx/decoder/common.h

+#include "base/basic_types.h"
+
+struct DecoderResult {
+  BaseFloat acoustic_score; 
+  std::vector<int32> words_idx;
+  std::vector<pair<int32, int32>> time_stamp;
+};

speechx/speechx/decoder/ctc_beam_search_decoder.cc

+#include "decoder/ctc_beam_search_decoder.h"
+
+#include "base/basic_types.h"
+#include "decoder/ctc_decoders/decoder_utils.h"
+
+namespace ppspeech {
+
+using std::vector;
+using FSTMATCH = fst::SortedMatcher<fst::StdVectorFst>;
+
+CTCBeamSearch::CTCBeamSearch(std::shared_ptr<CTCBeamSearchOptions> opts) :
+    opts_(opts),
+    vocabulary_(nullptr),
+    init_ext_scorer_(nullptr), 
+    blank_id(-1),
+    space_id(-1),
+    root(nullptr) {
+
+    LOG(INFO) << "dict path: " << _opts.dict_file;
+    vocabulary_ = std::make_shared<vector<string>>();
+    if (!basr::ReadDictToVector(_opts.dict_file, *vocabulary_)) {
+        LOG(INFO) << "load the dict failed";
+    }
+    LOG(INFO) << "read the vocabulary success, dict size: " << vocabulary_->size();
+
+    LOG(INFO) << "language model path: " << _opts.lm_path;
+    init_ext_scorer_ = std::make_shared<Scorer>(_opts.alpha, 
+                                                _opts.beta, 
+                                                _opts.lm_path, 
+                                                *vocabulary_);
+}
+
+void CTCBeamSearch::InitDecoder() {
+    
+    blank_id = 0;
+    auto it = std::find(vocabulary_->begin(), vocabulary_->end(), " ");
+    
+    space_id = it - vocabulary_->begin();
+    // if no space in vocabulary
+    if ((size_t)space_id >= vocabulary_->size()) {
+        space_id = -2;
+    }  
+
+    clear_prefixes();
+    
+    root = std::make_shared<PathTrie>();
+    root->score = root->log_prob_b_prev = 0.0;
+    prefixes.push_back(root.get());
+    if (init_ext_scorer_ != nullptr && !init_ext_scorer_->is_character_based()) {
+        auto fst_dict =
+            static_cast<fst::StdVectorFst *>(init_ext_scorer_->dictionary);
+        fst::StdVectorFst *dict_ptr = fst_dict->Copy(true);
+        root->set_dictionary(dict_ptr);
+        
+        auto matcher = std::make_shared<FSTMATCH>(*dict_ptr, fst::MATCH_INPUT);
+        root->set_matcher(matcher);
+    }
+}
+
+void CTCBeamSearch::ResetPrefixes() {
+  for (size_t i = 0; i < prefixes.size(); i++) {
+    if (prefixes[i] != nullptr) {
+      delete prefixes[i];
+      prefixes[i] = nullptr;
+    }
+  }
+}
+
+int CTCBeamSearch::DecodeLikelihoods(const vector<vector<float>>&probs, 
+                                      vector<string>& nbest_words) {
+  std::thread::id this_id = std::this_thread::get_id();
+  Timer timer;
+  vector<vector<double>> double_probs(probs.size(), vector<double>(probs[0].size(), 0));
+
+  int row = probs.size();
+  int col = probs[0].size();
+  for(int i = 0; i < row; i++) {
+    for (int j = 0; j < col; j++){
+      double_probs[i][j] = static_cast<double>(probs[i][j]);
+    }
+  }
+
+  timer.Reset();
+  vector<std::pair<double, string>> results = AdvanceDecoding(double_probs);
+  LOG(INFO) <<"ctc decoding elapsed time(s) " << static_cast<float>(timer.Elapsed()) / 1000.0f;
+  for (const auto& item : results) {
+    nbest_words.push_back(item.second);
+  }
+  return 0;
+} 
+
+vector<std::pair<double, string>> CTCBeamSearch::AdvanceDecoding(const vector<vector<double>>& probs_seq) {
+  size_t num_time_steps = probs_seq.size();
+  size_t beam_size = _opts.beam_size;
+  double cutoff_prob = _opts.cutoff_prob;
+  size_t cutoff_top_n = _opts.cutoff_top_n;
+    
+  for (size_t time_step = 0; time_step < num_time_steps; time_step++) {
+    const auto& prob = probs_seq[time_step];
+
+    float min_cutoff = -NUM_FLT_INF;
+    bool full_beam = false;
+    if (init_ext_scorer_ != nullptr) {
+      size_t num_prefixes = std::min(prefixes.size(), beam_size);
+      std::sort(prefixes.begin(), prefixes.begin() + num_prefixes,
+                prefix_compare);
+            
+      if (num_prefixes == 0) {
+        continue;
+      }
+      min_cutoff = prefixes[num_prefixes - 1]->score +
+                      std::log(prob[blank_id]) -
+                      std::max(0.0, init_ext_scorer_->beta);
+
+      full_beam = (num_prefixes == beam_size);
+    }
+        
+    vector<std::pair<size_t, float>> log_prob_idx =
+                get_pruned_log_probs(prob, cutoff_prob, cutoff_top_n);
+
+    // loop over chars
+    size_t log_prob_idx_len = log_prob_idx.size();
+    for (size_t index = 0; index < log_prob_idx_len; index++) {            
+      SearchOneChar(full_beam, log_prob_idx[index], min_cutoff);
+        
+    prefixes.clear();
+        
+    // update log probs
+    root->iterate_to_vec(prefixes);
+    // only preserve top beam_size prefixes
+    if (prefixes.size() >= beam_size) {
+      std::nth_element(prefixes.begin(),
+                       prefixes.begin() + beam_size,
+                       prefixes.end(),
+                       prefix_compare);
+      for (size_t i = beam_size; i < prefixes.size(); ++i) {
+        prefixes[i]->remove();
+      }
+    } // if 
+  } // for probs_seq
+
+  // score the last word of each prefix that doesn't end with space
+  LMRescore();
+  CalculateApproxScore();
+  return get_beam_search_result(prefixes, *vocabulary_, beam_size);
+}
+
+int CTCBeamSearch::SearchOneChar(const bool& full_beam,
+                                 const std::pair<size_t, float>& log_prob_idx,
+                                 const float& min_cutoff) {
+  size_t beam_size = _opts.beam_size;
+  const auto& c = log_prob_idx.first;
+  const auto& log_prob_c = log_prob_idx.second;
+  size_t prefixes_len = std::min(prefixes.size(), beam_size);
+    
+  for (size_t i = 0; i < prefixes_len; ++i) {
+    auto prefix = prefixes[i];
+    if (full_beam && log_prob_c + prefix->score < min_cutoff) {
+      break;
+    }
+
+    if (c == blank_id) {
+      prefix->log_prob_b_cur = log_sum_exp(
+                              prefix->log_prob_b_cur, 
+                              log_prob_c +
+                              prefix->score);
+      continue;
+    }
+
+    // repeated character
+    if (c == prefix->character) {
+      // p_{nb}(l;x_{1:t}) = p(c;x_{t})p(l;x_{1:t-1})
+      prefix->log_prob_nb_cur = log_sum_exp(
+                                  prefix->log_prob_nb_cur,
+                                  log_prob_c + 
+                                  prefix->log_prob_nb_prev);
+    }
+
+    // get new prefix
+    auto prefix_new = prefix->get_path_trie(c);
+    if (prefix_new != nullptr) {
+      float log_p = -NUM_FLT_INF;
+      if (c == prefix->character &&
+        prefix->log_prob_b_prev > -NUM_FLT_INF) { 
+         // p_{nb}(l^{+};x_{1:t}) = p(c;x_{t})p_{b}(l;x_{1:t-1})
+        log_p = log_prob_c + prefix->log_prob_b_prev;
+      } else if (c != prefix->character) {
+        // p_{nb}(l^{+};x_{1:t}) = p(c;x_{t}) p(l;x_{1:t-1})
+        log_p = log_prob_c + prefix->score;
+      }
+
+      // language model scoring
+      if (init_ext_scorer_ != nullptr &&
+          (c == space_id || init_ext_scorer_->is_character_based())) {
+        PathTrie *prefix_to_score = nullptr;
+        // skip scoring the space
+        if (init_ext_scorer_->is_character_based()) {
+            prefix_to_score = prefix_new;
+        } else {
+            prefix_to_score = prefix;
+        }
+
+        float score = 0.0;
+        vector<string> ngram;
+        ngram = init_ext_scorer_->make_ngram(prefix_to_score);
+        // lm score: p_{lm}(W)^{\alpha} + \beta
+        score = init_ext_scorer_->get_log_cond_prob(ngram) *
+                                init_ext_scorer_->alpha;
+        log_p += score;
+        log_p += init_ext_scorer_->beta;
+      }
+      // p_{nb}(l;x_{1:t})
+      prefix_new->log_prob_nb_cur =
+                      log_sum_exp(prefix_new->log_prob_nb_cur, 
+                                  log_p);
+    }
+  } // end of loop over prefix
+  return 0;
+}
+
+void CTCBeamSearch::CalculateApproxScore() {
+  size_t beam_size = _opts.beam_size;
+  size_t num_prefixes = std::min(prefixes.size(), beam_size);
+  std::sort(
+      prefixes.begin(), 
+      prefixes.begin() + num_prefixes, 
+      prefix_compare);
+
+  // compute aproximate ctc score as the return score, without affecting the
+  // return order of decoding result. To delete when decoder gets stable.
+  for (size_t i = 0; i < beam_size && i < prefixes.size(); ++i) {
+    double approx_ctc = prefixes[i]->score;
+    if (init_ext_scorer_ != nullptr) {
+      vector<int> output;
+      prefixes[i]->get_path_vec(output);
+      auto prefix_length = output.size();
+      auto words = init_ext_scorer_->split_labels(output);
+      // remove word insert
+      approx_ctc = approx_ctc - prefix_length * init_ext_scorer_->beta;
+      // remove language model weight:
+      approx_ctc -=
+          (init_ext_scorer_->get_sent_log_prob(words)) * init_ext_scorer_->alpha;
+    }
+    prefixes[i]->approx_ctc = approx_ctc;
+  }
+}
+
+void CTCBeamSearch::LMRescore() {
+  size_t beam_size = _opts.beam_size;
+  if (init_ext_scorer_ != nullptr && !init_ext_scorer_->is_character_based()) {
+    for (size_t i = 0; i < beam_size && i < prefixes.size(); ++i) {
+      auto prefix = prefixes[i];
+      if (!prefix->is_empty() && prefix->character != space_id) {
+        float score = 0.0;
+        vector<string> ngram = init_ext_scorer_->make_ngram(prefix);
+        score = init_ext_scorer_->get_log_cond_prob(ngram) * init_ext_scorer_->alpha;
+        score += init_ext_scorer_->beta;
+        prefix->score += score;
+      }
+    }
+  }
+}
+
+} // namespace ppspeech
\ No newline at end of file

speechx/speechx/decoder/ctc_beam_search_decoder.h

+#include "base/basic_types.h"
+
+#pragma once
+
+namespace ppspeech {
+
+struct CTCBeamSearchOptions {
+    std::string dict_file;
+    std::string lm_path;
+    BaseFloat alpha;
+    BaseFloat beta;
+    BaseFloat cutoff_prob;
+    int beam_size;
+    int cutoff_top_n;
+    int num_proc_bsearch;
+    CTCBeamSearchOptions() :
+        dict_file("./model/words.txt"),
+        lm_path("./model/lm.arpa"),
+        alpha(1.9f),
+        beta(5.0),
+        beam_size(300),
+        cutoff_prob(0.99f),
+        cutoff_top_n(40),
+        num_proc_bsearch(0) {
+    }
+
+    void Register(kaldi::OptionsItf* opts) {
+        opts->Register("dict", &dict_file, "dict file ");
+        opts->Register("lm-path", &lm_path, "language model file");
+        opts->Register("alpha", &alpha, "alpha");
+        opts->Register("beta", &beta, "beta");
+        opts->Register("beam-size", &beam_size, "beam size for beam search method");
+        opts->Register("cutoff-prob", &cutoff_prob, "cutoff probs");
+        opts->Register("cutoff-top-n", &cutoff_top_n, "cutoff top n");
+        opts->Register("num-proc-bsearch", &num_proc_bsearch, "num proc bsearch");
+    }
+};
+
+class CTCBeamSearch {
+public: 
+
+    CTCBeamSearch(std::shared_ptr<CTCBeamSearchOptions> opts);
+
+    ~CTCBeamSearch() {
+    }
+    bool InitDecoder();
+    int DecodeLikelihoods(const std::vector<std::vector<BaseFloat>>&probs, 
+                          std::vector<std::string>& nbest_words);
+
+    std::vector<DecodeResult>& GetDecodeResult() {
+        return decoder_results_;
+    }
+
+private:
+  void ResetPrefixes();
+  int32 SearchOneChar(const bool& full_beam,
+                      const std::pair<size_t, BaseFloat>& log_prob_idx,
+                      const BaseFloat& min_cutoff);
+  void CalculateApproxScore();
+  void LMRescore();
+  std::vector<std::pair<double, std::string>> 
+    AdvanceDecoding(const std::vector<std::vector<double>>& probs_seq);
+  CTCBeamSearchOptions opts_;
+  std::shared_ptr<Scorer> init_ext_scorer_; // todo separate later
+  std::vector<DecodeResult> decoder_results_;
+  std::vector<std::vector<std::string>> vocabulary_; // todo remove later
+
+  size_t blank_id;        
+  int space_id;
+  std::shared_ptr<PathTrie> root;
+  std::vector<PathTrie*> prefixes;
+};
+
+} // namespace basr
\ No newline at end of file

speechx/speechx/decoder/ctc_decoders

+../../../third_party/ctc_decoders
\ No newline at end of file

speechx/speechx/kaldi/decoder/lattice-faster-online-decoder.cc

+// decoder/lattice-faster-online-decoder.cc
+
+// Copyright 2009-2012  Microsoft Corporation  Mirko Hannemann
+//           2013-2014  Johns Hopkins University (Author: Daniel Povey)
+//                2014  Guoguo Chen
+//                2014  IMSL, PKU-HKUST (author: Wei Shi)
+//                2018  Zhehuai Chen
+
+// See ../../COPYING for clarification regarding multiple authors
+//
+// 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
+//
+// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
+// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+// MERCHANTABLITY OR NON-INFRINGEMENT.
+// See the Apache 2 License for the specific language governing permissions and
+// limitations under the License.
+
+// see note at the top of lattice-faster-decoder.cc, about how to maintain this
+// file in sync with lattice-faster-decoder.cc
+
+#include "decoder/lattice-faster-online-decoder.h"
+#include "lat/lattice-functions.h"
+
+namespace kaldi {
+
+template <typename FST>
+bool LatticeFasterOnlineDecoderTpl<FST>::TestGetBestPath(
+    bool use_final_probs) const {
+  Lattice lat1;
+  {
+    Lattice raw_lat;
+    this->GetRawLattice(&raw_lat, use_final_probs);
+    ShortestPath(raw_lat, &lat1);
+  }
+  Lattice lat2;
+  GetBestPath(&lat2, use_final_probs);
+  BaseFloat delta = 0.1;
+  int32 num_paths = 1;
+  if (!fst::RandEquivalent(lat1, lat2, num_paths, delta, rand())) {
+    KALDI_WARN << "Best-path test failed";
+    return false;
+  } else {
+    return true;
+  }
+}
+
+
+// Outputs an FST corresponding to the single best path through the lattice.
+template <typename FST>
+bool LatticeFasterOnlineDecoderTpl<FST>::GetBestPath(Lattice *olat,
+                                                     bool use_final_probs) const {
+  olat->DeleteStates();
+  BaseFloat final_graph_cost;
+  BestPathIterator iter = BestPathEnd(use_final_probs, &final_graph_cost);
+  if (iter.Done())
+    return false;  // would have printed warning.
+  StateId state = olat->AddState();
+  olat->SetFinal(state, LatticeWeight(final_graph_cost, 0.0));
+  while (!iter.Done()) {
+    LatticeArc arc;
+    iter = TraceBackBestPath(iter, &arc);
+    arc.nextstate = state;
+    StateId new_state = olat->AddState();
+    olat->AddArc(new_state, arc);
+    state = new_state;
+  }
+  olat->SetStart(state);
+  return true;
+}
+
+template <typename FST>
+typename LatticeFasterOnlineDecoderTpl<FST>::BestPathIterator LatticeFasterOnlineDecoderTpl<FST>::BestPathEnd(
+    bool use_final_probs,
+    BaseFloat *final_cost_out) const {
+  if (this->decoding_finalized_ && !use_final_probs)
+    KALDI_ERR << "You cannot call FinalizeDecoding() and then call "
+              << "BestPathEnd() with use_final_probs == false";
+  KALDI_ASSERT(this->NumFramesDecoded() > 0 &&
+               "You cannot call BestPathEnd if no frames were decoded.");
+
+  unordered_map<Token*, BaseFloat> final_costs_local;
+
+  const unordered_map<Token*, BaseFloat> &final_costs =
+      (this->decoding_finalized_ ? this->final_costs_ :final_costs_local);
+  if (!this->decoding_finalized_ && use_final_probs)
+    this->ComputeFinalCosts(&final_costs_local, NULL, NULL);
+
+  // Singly linked list of tokens on last frame (access list through "next"
+  // pointer).
+  BaseFloat best_cost = std::numeric_limits<BaseFloat>::infinity();
+  BaseFloat best_final_cost = 0;
+  Token *best_tok = NULL;
+  for (Token *tok = this->active_toks_.back().toks;
+       tok != NULL; tok = tok->next) {
+    BaseFloat cost = tok->tot_cost, final_cost = 0.0;
+    if (use_final_probs && !final_costs.empty()) {
+      // if we are instructed to use final-probs, and any final tokens were
+      // active on final frame, include the final-prob in the cost of the token.
+      typename unordered_map<Token*, BaseFloat>::const_iterator
+          iter = final_costs.find(tok);
+      if (iter != final_costs.end()) {
+        final_cost = iter->second;
+        cost += final_cost;
+      } else {
+        cost = std::numeric_limits<BaseFloat>::infinity();
+      }
+    }
+    if (cost < best_cost) {
+      best_cost = cost;
+      best_tok = tok;
+      best_final_cost = final_cost;
+    }
+  }
+  if (best_tok == NULL) {  // this should not happen, and is likely a code error or
+    // caused by infinities in likelihoods, but I'm not making
+    // it a fatal error for now.
+    KALDI_WARN << "No final token found.";
+  }
+  if (final_cost_out)
+    *final_cost_out = best_final_cost;
+  return BestPathIterator(best_tok, this->NumFramesDecoded() - 1);
+}
+
+
+template <typename FST>
+typename LatticeFasterOnlineDecoderTpl<FST>::BestPathIterator LatticeFasterOnlineDecoderTpl<FST>::TraceBackBestPath(
+    BestPathIterator iter, LatticeArc *oarc) const {
+  KALDI_ASSERT(!iter.Done() && oarc != NULL);
+  Token *tok = static_cast<Token*>(iter.tok);
+  int32 cur_t = iter.frame, step_t = 0;
+  if (tok->backpointer != NULL) {
+    // retrieve the correct forward link(with the best link cost)
+    BaseFloat best_cost = std::numeric_limits<BaseFloat>::infinity();
+    ForwardLinkT *link;
+    for (link = tok->backpointer->links;
+         link != NULL; link = link->next) {
+      if (link->next_tok == tok) { // this is a link to "tok"
+        BaseFloat graph_cost = link->graph_cost, 
+                  acoustic_cost = link->acoustic_cost;
+        BaseFloat cost = graph_cost + acoustic_cost;
+        if (cost < best_cost) {
+          oarc->ilabel = link->ilabel;
+          oarc->olabel = link->olabel;
+          if (link->ilabel != 0) {
+            KALDI_ASSERT(static_cast<size_t>(cur_t) < this->cost_offsets_.size());
+            acoustic_cost -= this->cost_offsets_[cur_t];
+            step_t = -1;
+          } else {
+            step_t = 0;
+          }
+          oarc->weight = LatticeWeight(graph_cost, acoustic_cost);
+          best_cost = cost;
+        }
+      }
+    }
+    if (link == NULL &&
+        best_cost == std::numeric_limits<BaseFloat>::infinity()) { // Did not find correct link.
+      KALDI_ERR << "Error tracing best-path back (likely "
+                << "bug in token-pruning algorithm)";
+    }
+  } else {
+    oarc->ilabel = 0;
+    oarc->olabel = 0;
+    oarc->weight = LatticeWeight::One(); // zero costs.
+  }
+  return BestPathIterator(tok->backpointer, cur_t + step_t);
+}
+
+template <typename FST>
+bool LatticeFasterOnlineDecoderTpl<FST>::GetRawLatticePruned(
+    Lattice *ofst,
+    bool use_final_probs,
+    BaseFloat beam) const {
+  typedef LatticeArc Arc;
+  typedef Arc::StateId StateId;
+  typedef Arc::Weight Weight;
+  typedef Arc::Label Label;
+
+  // Note: you can't use the old interface (Decode()) if you want to
+  // get the lattice with use_final_probs = false.  You'd have to do
+  // InitDecoding() and then AdvanceDecoding().
+  if (this->decoding_finalized_ && !use_final_probs)
+    KALDI_ERR << "You cannot call FinalizeDecoding() and then call "
+              << "GetRawLattice() with use_final_probs == false";
+
+  unordered_map<Token*, BaseFloat> final_costs_local;
+
+  const unordered_map<Token*, BaseFloat> &final_costs =
+      (this->decoding_finalized_ ? this->final_costs_ : final_costs_local);
+  if (!this->decoding_finalized_ && use_final_probs)
+    this->ComputeFinalCosts(&final_costs_local, NULL, NULL);
+
+  ofst->DeleteStates();
+  // num-frames plus one (since frames are one-based, and we have
+  // an extra frame for the start-state).
+  int32 num_frames = this->active_toks_.size() - 1;
+  KALDI_ASSERT(num_frames > 0);
+  for (int32 f = 0; f <= num_frames; f++) {
+    if (this->active_toks_[f].toks == NULL) {
+      KALDI_WARN << "No tokens active on frame " << f
+                 << ": not producing lattice.\n";
+      return false;
+    }
+  }
+  unordered_map<Token*, StateId> tok_map;
+  std::queue<std::pair<Token*, int32> > tok_queue;
+  // First initialize the queue and states.  Put the initial state on the queue;
+  // this is the last token in the list active_toks_[0].toks.
+  for (Token *tok = this->active_toks_[0].toks;
+       tok != NULL; tok = tok->next) {
+    if (tok->next == NULL) {
+      tok_map[tok] = ofst->AddState();
+      ofst->SetStart(tok_map[tok]);
+      std::pair<Token*, int32> tok_pair(tok, 0);  // #frame = 0
+      tok_queue.push(tok_pair);
+    }
+  }
+
+  // Next create states for "good" tokens
+  while (!tok_queue.empty()) {
+    std::pair<Token*, int32> cur_tok_pair = tok_queue.front();
+    tok_queue.pop();
+    Token *cur_tok = cur_tok_pair.first;
+    int32 cur_frame = cur_tok_pair.second;
+    KALDI_ASSERT(cur_frame >= 0 &&
+                 cur_frame <= this->cost_offsets_.size());
+
+    typename unordered_map<Token*, StateId>::const_iterator iter =
+        tok_map.find(cur_tok);
+    KALDI_ASSERT(iter != tok_map.end());
+    StateId cur_state = iter->second;
+
+    for (ForwardLinkT *l = cur_tok->links;
+         l != NULL;
+         l = l->next) {
+      Token *next_tok = l->next_tok;
+      if (next_tok->extra_cost < beam) {
+        // so both the current and the next token are good; create the arc
+        int32 next_frame = l->ilabel == 0 ? cur_frame : cur_frame + 1;
+        StateId nextstate;
+        if (tok_map.find(next_tok) == tok_map.end()) {
+          nextstate = tok_map[next_tok] = ofst->AddState();
+          tok_queue.push(std::pair<Token*, int32>(next_tok, next_frame));
+        } else {
+          nextstate = tok_map[next_tok];
+        }
+        BaseFloat cost_offset = (l->ilabel != 0 ?
+                                 this->cost_offsets_[cur_frame] : 0);
+        Arc arc(l->ilabel, l->olabel,
+                Weight(l->graph_cost, l->acoustic_cost - cost_offset),
+                nextstate);
+        ofst->AddArc(cur_state, arc);
+      }
+    }
+    if (cur_frame == num_frames) {
+      if (use_final_probs && !final_costs.empty()) {
+        typename unordered_map<Token*, BaseFloat>::const_iterator iter =
+            final_costs.find(cur_tok);
+        if (iter != final_costs.end())
+          ofst->SetFinal(cur_state, LatticeWeight(iter->second, 0));
+      } else {
+        ofst->SetFinal(cur_state, LatticeWeight::One());
+      }
+    }
+  }
+  return (ofst->NumStates() != 0);
+}
+
+
+
+// Instantiate the template for the FST types that we'll need.
+template class LatticeFasterOnlineDecoderTpl<fst::Fst<fst::StdArc> >;
+template class LatticeFasterOnlineDecoderTpl<fst::VectorFst<fst::StdArc> >;
+template class LatticeFasterOnlineDecoderTpl<fst::ConstFst<fst::StdArc> >;
+template class LatticeFasterOnlineDecoderTpl<fst::ConstGrammarFst >;
+template class LatticeFasterOnlineDecoderTpl<fst::VectorGrammarFst >;
+
+
+} // end namespace kaldi.

speechx/speechx/kaldi/decoder/lattice-faster-online-decoder.h

+// decoder/lattice-faster-online-decoder.h
+
+// Copyright 2009-2013  Microsoft Corporation;  Mirko Hannemann;
+//           2013-2014  Johns Hopkins University (Author: Daniel Povey)
+//                2014  Guoguo Chen
+//                2018  Zhehuai Chen
+
+// See ../../COPYING for clarification regarding multiple authors
+//
+// 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
+//
+// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
+// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+// MERCHANTABLITY OR NON-INFRINGEMENT.
+// See the Apache 2 License for the specific language governing permissions and
+// limitations under the License.
+
+// see note at the top of lattice-faster-decoder.h, about how to maintain this
+// file in sync with lattice-faster-decoder.h
+
+
+#ifndef KALDI_DECODER_LATTICE_FASTER_ONLINE_DECODER_H_
+#define KALDI_DECODER_LATTICE_FASTER_ONLINE_DECODER_H_
+
+#include "util/stl-utils.h"
+#include "util/hash-list.h"
+#include "fst/fstlib.h"
+#include "itf/decodable-itf.h"
+#include "fstext/fstext-lib.h"
+#include "lat/determinize-lattice-pruned.h"
+#include "lat/kaldi-lattice.h"
+#include "decoder/lattice-faster-decoder.h"
+
+namespace kaldi {
+
+
+
+/** LatticeFasterOnlineDecoderTpl is as LatticeFasterDecoderTpl but also
+    supports an efficient way to get the best path (see the function
+    BestPathEnd()), which is useful in endpointing and in situations where you
+    might want to frequently access the best path.
+
+    This is only templated on the FST type, since the Token type is required to
+    be BackpointerToken.  Actually it only makes sense to instantiate
+    LatticeFasterDecoderTpl with Token == BackpointerToken if you do so indirectly via
+    this child class.
+ */
+template <typename FST>
+class LatticeFasterOnlineDecoderTpl:
+      public LatticeFasterDecoderTpl<FST, decoder::BackpointerToken> {
+ public:
+  using Arc = typename FST::Arc;
+  using Label = typename Arc::Label;
+  using StateId = typename Arc::StateId;
+  using Weight = typename Arc::Weight;
+  using Token = decoder::BackpointerToken;
+  using ForwardLinkT = decoder::ForwardLink<Token>;
+
+  // Instantiate this class once for each thing you have to decode.
+  // This version of the constructor does not take ownership of
+  // 'fst'.
+  LatticeFasterOnlineDecoderTpl(const FST &fst,
+                                const LatticeFasterDecoderConfig &config):
+      LatticeFasterDecoderTpl<FST, Token>(fst, config) { }
+
+  // This version of the initializer takes ownership of 'fst', and will delete
+  // it when this object is destroyed.
+  LatticeFasterOnlineDecoderTpl(const LatticeFasterDecoderConfig &config,
+                                FST *fst):
+      LatticeFasterDecoderTpl<FST, Token>(config, fst) { }
+
+
+  struct BestPathIterator {
+    void *tok;
+    int32 frame;
+    // note, "frame" is the frame-index of the frame you'll get the
+    // transition-id for next time, if you call TraceBackBestPath on this
+    // iterator (assuming it's not an epsilon transition).  Note that this
+    // is one less than you might reasonably expect, e.g. it's -1 for
+    // the nonemitting transitions before the first frame.
+    BestPathIterator(void *t, int32 f): tok(t), frame(f) { }
+    bool Done() const { return tok == NULL; }
+  };
+
+
+  /// Outputs an FST corresponding to the single best path through the lattice.
+  /// This is quite efficient because it doesn't get the entire raw lattice and find
+  /// the best path through it; instead, it uses the BestPathEnd and BestPathIterator
+  /// so it basically traces it back through the lattice.
+  /// Returns true if result is nonempty (using the return status is deprecated,
+  /// it will become void).  If "use_final_probs" is true AND we reached the
+  /// final-state of the graph then it will include those as final-probs, else
+  /// it will treat all final-probs as one.
+  bool GetBestPath(Lattice *ofst,
+                   bool use_final_probs = true) const;
+
+
+  /// This function does a self-test of GetBestPath().  Returns true on
+  /// success; returns false and prints a warning on failure.
+  bool TestGetBestPath(bool use_final_probs = true) const;
+
+
+  /// This function returns an iterator that can be used to trace back
+  /// the best path.  If use_final_probs == true and at least one final state
+  /// survived till the end, it will use the final-probs in working out the best
+  /// final Token, and will output the final cost to *final_cost (if non-NULL),
+  /// else it will use only the forward likelihood, and will put zero in
+  /// *final_cost (if non-NULL).
+  /// Requires that NumFramesDecoded() > 0.
+  BestPathIterator BestPathEnd(bool use_final_probs,
+                               BaseFloat *final_cost = NULL) const;
+
+
+  /// This function can be used in conjunction with BestPathEnd() to trace back
+  /// the best path one link at a time (e.g. this can be useful in endpoint
+  /// detection).  By "link" we mean a link in the graph; not all links cross
+  /// frame boundaries, but each time you see a nonzero ilabel you can interpret
+  /// that as a frame.  The return value is the updated iterator.  It outputs
+  /// the ilabel and olabel, and the (graph and acoustic) weight to the "arc" pointer,
+  /// while leaving its "nextstate" variable unchanged.
+  BestPathIterator TraceBackBestPath(
+      BestPathIterator iter, LatticeArc *arc) const;
+
+
+  /// Behaves the same as GetRawLattice but only processes tokens whose
+  /// extra_cost is smaller than the best-cost plus the specified beam.
+  /// It is only worthwhile to call this function if beam is less than
+  /// the lattice_beam specified in the config; otherwise, it would
+  /// return essentially the same thing as GetRawLattice, but more slowly.
+  bool GetRawLatticePruned(Lattice *ofst,
+                           bool use_final_probs,
+                           BaseFloat beam) const;
+
+  KALDI_DISALLOW_COPY_AND_ASSIGN(LatticeFasterOnlineDecoderTpl);
+};
+
+typedef LatticeFasterOnlineDecoderTpl<fst::StdFst> LatticeFasterOnlineDecoder;
+
+
+} // end namespace kaldi.
+
+#endif

speechx/speechx/kaldi/lat/determinize-lattice-pruned-test.cc

+// lat/determinize-lattice-pruned-test.cc
+
+// Copyright 2009-2012  Microsoft Corporation
+//           2012-2013  Johns Hopkins University (Author: Daniel Povey)
+
+// See ../../COPYING for clarification regarding multiple authors
+//
+// 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
+//
+// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
+// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+// MERCHANTABLITY OR NON-INFRINGEMENT.
+// See the Apache 2 License for the specific language governing permissions and
+// limitations under the License.
+
+#include "lat/determinize-lattice-pruned.h"
+#include "fstext/lattice-utils.h"
+#include "fstext/fst-test-utils.h"
+#include "lat/kaldi-lattice.h"
+#include "lat/lattice-functions.h"
+
+namespace fst {
+// Caution: these tests are not as generic as you might think from all the
+// templates in the code.  They are basically only valid for LatticeArc.
+// This is partly due to the fact that certain templates need to be instantiated
+// in other .cc files in this directory.
+
+// test that determinization proceeds correctly on general
+// FSTs (not guaranteed determinzable, but we use the
+// max-states option to stop it getting out of control).
+template<class Arc> void TestDeterminizeLatticePruned() {
+  typedef kaldi::int32 Int;
+  typedef typename Arc::Weight Weight;
+  typedef ArcTpl<CompactLatticeWeightTpl<Weight, Int> > CompactArc;
+
+  for(int i = 0; i < 100; i++) {
+    RandFstOptions opts;
+    opts.n_states = 4;
+    opts.n_arcs = 10;
+    opts.n_final = 2;
+    opts.allow_empty = false;
+    opts.weight_multiplier = 0.5; // impt for the randomly generated weights
+    opts.acyclic = true;
+    // to be exactly representable in float,
+    // or this test fails because numerical differences can cause symmetry in
+    // weights to be broken, which causes the wrong path to be chosen as far
+    // as the string part is concerned.
+
+    VectorFst<Arc> *fst = RandPairFst<Arc>(opts);
+
+    bool sorted = TopSort(fst);
+    KALDI_ASSERT(sorted);
+
+    ILabelCompare<Arc> ilabel_comp;
+    if (kaldi::Rand() % 2 == 0)
+      ArcSort(fst, ilabel_comp);
+
+    std::cout << "FST before lattice-determinizing is:\n";
+    {
+      FstPrinter<Arc> fstprinter(*fst, NULL, NULL, NULL, false, true, "\t");
+      fstprinter.Print(&std::cout, "standard output");
+    }
+    VectorFst<Arc> det_fst;
+    try {
+      DeterminizeLatticePrunedOptions lat_opts;
+      lat_opts.max_mem = ((kaldi::Rand() % 2 == 0) ? 100 : 1000);
+      lat_opts.max_states = ((kaldi::Rand() % 2 == 0) ? -1 : 20);
+      lat_opts.max_arcs = ((kaldi::Rand() % 2 == 0) ? -1 : 30);
+      bool ans = DeterminizeLatticePruned<Weight>(*fst, 10.0, &det_fst, lat_opts);
+
+      std::cout << "FST after lattice-determinizing is:\n";
+      {
+        FstPrinter<Arc> fstprinter(det_fst, NULL, NULL, NULL, false, true, "\t");
+        fstprinter.Print(&std::cout, "standard output");
+      }
+      KALDI_ASSERT(det_fst.Properties(kIDeterministic, true) & kIDeterministic);
+      // OK, now determinize it a different way and check equivalence.
+      // [note: it's not normal determinization, it's taking the best path
+      // for any input-symbol sequence....
+
+
+      VectorFst<Arc> pruned_fst(*fst);
+      if (pruned_fst.NumStates() != 0)
+        kaldi::PruneLattice(10.0, &pruned_fst);
+
+      VectorFst<CompactArc> compact_pruned_fst, compact_pruned_det_fst;
+      ConvertLattice<Weight, Int>(pruned_fst, &compact_pruned_fst, false);
+      std::cout << "Compact pruned FST is:\n";
+      {
+        FstPrinter<CompactArc> fstprinter(compact_pruned_fst, NULL, NULL, NULL, false, true, "\t");
+        fstprinter.Print(&std::cout, "standard output");
+      }
+      ConvertLattice<Weight, Int>(det_fst, &compact_pruned_det_fst, false);
+
+      std::cout << "Compact version of determinized FST is:\n";
+      {
+        FstPrinter<CompactArc> fstprinter(compact_pruned_det_fst, NULL, NULL, NULL, false, true, "\t");
+        fstprinter.Print(&std::cout, "standard output");
+      }
+
+      if (ans)
+        KALDI_ASSERT(RandEquivalent(compact_pruned_det_fst, compact_pruned_fst, 5/*paths*/, 0.01/*delta*/, kaldi::Rand()/*seed*/, 100/*path length, max*/));
+    } catch (...) {
+      std::cout << "Failed to lattice-determinize this FST (probably not determinizable)\n";
+    }
+    delete fst;
+  }
+}
+
+// test that determinization proceeds without crash on acyclic FSTs
+// (guaranteed determinizable in this sense).
+template<class Arc> void TestDeterminizeLatticePruned2() {
+  typedef typename Arc::Weight Weight;
+  RandFstOptions opts;
+  opts.acyclic = true;
+  for(int i = 0; i < 100; i++) {
+    VectorFst<Arc> *fst = RandPairFst<Arc>(opts);
+    std::cout << "FST before lattice-determinizing is:\n";
+    {
+      FstPrinter<Arc> fstprinter(*fst, NULL, NULL, NULL, false, true, "\t");
+      fstprinter.Print(&std::cout, "standard output");
+    }
+    VectorFst<Arc> ofst;
+    DeterminizeLatticePruned<Weight>(*fst, 10.0, &ofst);
+    std::cout << "FST after lattice-determinizing is:\n";
+    {
+      FstPrinter<Arc> fstprinter(ofst, NULL, NULL, NULL, false, true, "\t");
+      fstprinter.Print(&std::cout, "standard output");
+    }
+    delete fst;
+  }
+}
+
+
+} // end namespace fst
+
+int main() {
+  using namespace fst;
+  TestDeterminizeLatticePruned<kaldi::LatticeArc>();
+  TestDeterminizeLatticePruned2<kaldi::LatticeArc>();
+  std::cout << "Tests succeeded\n";
+}

speechx/speechx/kaldi/lat/determinize-lattice-pruned.h

+// lat/determinize-lattice-pruned.h
+
+// Copyright 2009-2012  Microsoft Corporation
+//           2012-2013  Johns Hopkins University (Author: Daniel Povey)
+//                2014  Guoguo Chen
+
+// See ../../COPYING for clarification regarding multiple authors
+//
+// 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
+//
+// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
+// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+// MERCHANTABLITY OR NON-INFRINGEMENT.
+// See the Apache 2 License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef KALDI_LAT_DETERMINIZE_LATTICE_PRUNED_H_
+#define KALDI_LAT_DETERMINIZE_LATTICE_PRUNED_H_
+#include <fst/fstlib.h>
+#include <fst/fst-decl.h>
+#include <algorithm>
+#include <map>
+#include <set>
+#include <vector>
+#include "fstext/lattice-weight.h"
+#include "itf/transition-information.h"
+#include "itf/options-itf.h"
+#include "lat/kaldi-lattice.h"
+
+namespace fst {
+
+/// \addtogroup fst_extensions
+///  @{
+
+
+// For example of usage, see test-determinize-lattice-pruned.cc
+
+/*
+   DeterminizeLatticePruned implements a special form of determinization with
+   epsilon removal, optimized for a phase of lattice generation.  This algorithm
+   also does pruning at the same time-- the combination is more efficient as it
+   somtimes prevents us from creating a lot of states that would later be pruned
+   away.  This allows us to increase the lattice-beam and not have the algorithm
+   blow up.  Also, because our algorithm processes states in order from those
+   that appear on high-scoring paths down to those that appear on low-scoring
+   paths, we can easily terminate the algorithm after a certain specified number
+   of states or arcs.
+
+   The input is an FST with weight-type BaseWeightType (usually a pair of floats,
+   with a lexicographical type of order, such as LatticeWeightTpl<float>).
+   Typically this would be a state-level lattice, with input symbols equal to
+   words, and output-symbols equal to p.d.f's (so like the inverse of HCLG).  Imagine representing this as an
+   acceptor of type CompactLatticeWeightTpl<float>, in which the input/output
+   symbols are words, and the weights contain the original weights together with
+   strings (with zero or one symbol in them) containing the original output labels
+   (the p.d.f.'s).  We determinize this using acceptor determinization with
+   epsilon removal.  Remember (from lattice-weight.h) that
+   CompactLatticeWeightTpl has a special kind of semiring where we always take
+   the string corresponding to the best cost (of type BaseWeightType), and
+   discard the other.  This corresponds to taking the best output-label sequence
+   (of p.d.f.'s) for each input-label sequence (of words).  We couldn't use the
+   Gallic weight for this, or it would die as soon as it detected that the input
+   FST was non-functional.  In our case, any acyclic FST (and many cyclic ones)
+   can be determinized.
+   We assume that there is a function
+      Compare(const BaseWeightType &a, const BaseWeightType &b)
+   that returns (-1, 0, 1) according to whether (a < b, a == b, a > b) in the
+   total order on the BaseWeightType... this information should be the
+   same as NaturalLess would give, but it's more efficient to do it this way.
+   You can define this for things like TropicalWeight if you need to instantiate
+   this class for that weight type.
+
+   We implement this determinization in a special way to make it efficient for
+   the types of FSTs that we will apply it to.  One issue is that if we
+   explicitly represent the strings (in CompactLatticeWeightTpl) as vectors of
+   type vector<IntType>, the algorithm takes time quadratic in the length of
+   words (in states), because propagating each arc involves copying a whole
+   vector (of integers representing p.d.f.'s).  Instead we use a hash structure
+   where each string is a pointer (Entry*), and uses a hash from (Entry*,
+   IntType), to the successor string (and a way to get the latest IntType and the
+   ancestor Entry*).  [this is the class LatticeStringRepository].
+
+   Another issue is that rather than representing a determinized-state as a
+   collection of (state, weight), we represent it in a couple of reduced forms.
+   Suppose a determinized-state is a collection of (state, weight) pairs; call
+   this the "canonical representation".  Note: these collections are always
+   normalized to remove any common weight and string part.  Define end-states as
+   the subset of states that have an arc out of them with a label on, or are
+   final.  If we represent a determinized-state a the set of just its (end-state,
+   weight) pairs, this will be a valid and more compact representation, and will
+   lead to a smaller set of determinized states (like early minimization).  Call
+   this collection of (end-state, weight) pairs the "minimal representation".  As
+   a mechanism to reduce compute, we can also consider another representation.
+   In the determinization algorithm, we start off with a set of (begin-state,
+   weight) pairs (where the "begin-states" are initial or have a label on the
+   transition into them), and the "canonical representation" consists of the
+   epsilon-closure of this set (i.e. follow epsilons).  Call this set of
+   (begin-state, weight) pairs, appropriately normalized, the "initial
+   representation".  If two initial representations are the same, the "canonical
+   representation" and hence the "minimal representation" will be the same.  We
+   can use this to reduce compute.  Note that if two initial representations are
+   different, this does not preclude the other representations from being the same.
+
+*/
+
+
+struct DeterminizeLatticePrunedOptions {
+  float delta; // A small offset used to measure equality of weights.
+  int max_mem; // If >0, determinization will fail and return false
+  // when the algorithm's (approximate) memory consumption crosses this threshold.
+  int max_loop; // If >0, can be used to detect non-determinizable input
+  // (a case that wouldn't be caught by max_mem).
+  int max_states;
+  int max_arcs;
+  float retry_cutoff;
+  DeterminizeLatticePrunedOptions(): delta(kDelta),
+                                     max_mem(-1),
+                                     max_loop(-1),
+                                     max_states(-1),
+                                     max_arcs(-1),
+                                     retry_cutoff(0.5) { }
+  void Register (kaldi::OptionsItf *opts) {
+    opts->Register("delta", &delta, "Tolerance used in determinization");
+    opts->Register("max-mem", &max_mem, "Maximum approximate memory usage in "
+                   "determinization (real usage might be many times this)");
+    opts->Register("max-arcs", &max_arcs, "Maximum number of arcs in "
+                   "output FST (total, not per state");
+    opts->Register("max-states", &max_states, "Maximum number of arcs in output "
+                   "FST (total, not per state");
+    opts->Register("max-loop", &max_loop, "Option used to detect a particular "
+                   "type of determinization failure, typically due to invalid input "
+                   "(e.g., negative-cost loops)");
+    opts->Register("retry-cutoff", &retry_cutoff, "Controls pruning un-determinized "
+                   "lattice and retrying determinization: if effective-beam < "
+                   "retry-cutoff * beam, we prune the raw lattice and retry.  Avoids "
+                   "ever getting empty output for long segments.");
+  }
+};
+
+struct DeterminizeLatticePhonePrunedOptions {
+  // delta: a small offset used to measure equality of weights.
+  float delta;
+  // max_mem: if > 0, determinization will fail and return false when the
+  // algorithm's (approximate) memory consumption crosses this threshold.
+  int max_mem;
+  // phone_determinize: if true, do a first pass determinization on both phones
+  // and words.
+  bool phone_determinize;
+  // word_determinize: if true, do a second pass determinization on words only.
+  bool word_determinize;
+  // minimize: if true, push and minimize after determinization.
+  bool minimize;
+  DeterminizeLatticePhonePrunedOptions(): delta(kDelta),
+                                          max_mem(50000000),
+                                          phone_determinize(true),
+                                          word_determinize(true),
+                                          minimize(false) {}
+  void Register (kaldi::OptionsItf *opts) {
+    opts->Register("delta", &delta, "Tolerance used in determinization");
+    opts->Register("max-mem", &max_mem, "Maximum approximate memory usage in "
+                   "determinization (real usage might be many times this).");
+    opts->Register("phone-determinize", &phone_determinize, "If true, do an "
+                   "initial pass of determinization on both phones and words (see"
+                   " also --word-determinize)");
+    opts->Register("word-determinize", &word_determinize, "If true, do a second "
+                   "pass of determinization on words only (see also "
+                   "--phone-determinize)");
+    opts->Register("minimize", &minimize, "If true, push and minimize after "
+                   "determinization.");
+  }
+};
+
+/**
+    This function implements the normal version of DeterminizeLattice, in which the
+    output strings are represented using sequences of arcs, where all but the
+    first one has an epsilon on the input side.  It also prunes using the beam
+    in the "prune" parameter.  The input FST must be topologically sorted in order
+    for the algorithm to work. For efficiency it is recommended to sort ilabel as well.
+    Returns true on success, and false if it had to terminate the determinization
+    earlier than specified by the "prune" beam-- that is, if it terminated because
+    of the max_mem, max_loop or max_arcs constraints in the options.
+    CAUTION: you may want to use the version below which outputs to CompactLattice.
+*/
+template<class Weight>
+bool DeterminizeLatticePruned(
+    const ExpandedFst<ArcTpl<Weight> > &ifst,
+    double prune,
+    MutableFst<ArcTpl<Weight> > *ofst,
+    DeterminizeLatticePrunedOptions opts = DeterminizeLatticePrunedOptions());
+
+
+/*  This is a version of DeterminizeLattice with a slightly more "natural" output format,
+    where the output sequences are encoded using the CompactLatticeArcTpl template
+    (i.e. the sequences of output symbols are represented directly as strings The input
+    FST must be topologically sorted in order for the algorithm to work. For efficiency
+    it is recommended to sort the ilabel for the input FST as well.
+    Returns true on normal success, and false if it had to terminate the determinization
+    earlier than specified by the "prune" beam-- that is, if it terminated because
+    of the max_mem, max_loop or max_arcs constraints in the options.
+    CAUTION: if Lattice is the input, you need to Invert() before calling this,
+    so words are on the input side.
+*/
+template<class Weight, class IntType>
+bool DeterminizeLatticePruned(
+    const ExpandedFst<ArcTpl<Weight> >&ifst,
+    double prune,
+    MutableFst<ArcTpl<CompactLatticeWeightTpl<Weight, IntType> > > *ofst,
+    DeterminizeLatticePrunedOptions opts = DeterminizeLatticePrunedOptions());
+
+/** This function takes in lattices and inserts phones at phone boundaries. It
+    uses the transition model to work out the transition_id to phone map. The
+    returning value is the starting index of the phone label. Typically we pick
+    (maximum_output_label_index + 1) as this value. The inserted phones are then
+    mapped to (returning_value + original_phone_label) in the new lattice. The
+    returning value will be used by DeterminizeLatticeDeletePhones() where it
+    works out the phones according to this value.
+*/
+template<class Weight>
+typename ArcTpl<Weight>::Label DeterminizeLatticeInsertPhones(
+    const kaldi::TransitionInformation &trans_model,
+    MutableFst<ArcTpl<Weight> > *fst);
+
+/** This function takes in lattices and deletes "phones" from them. The "phones"
+    here are actually any label that is larger than first_phone_label because
+    when we insert phones into the lattice, we map the original phone label to
+    (first_phone_label + original_phone_label). It is supposed to be used
+    together with DeterminizeLatticeInsertPhones()
+*/
+template<class Weight>
+void DeterminizeLatticeDeletePhones(
+    typename ArcTpl<Weight>::Label first_phone_label,
+    MutableFst<ArcTpl<Weight> > *fst);
+
+/** This function is a wrapper of DeterminizeLatticePhonePrunedFirstPass() and
+    DeterminizeLatticePruned(). If --phone-determinize is set to true, it first
+    calls DeterminizeLatticePhonePrunedFirstPass() to do the initial pass of
+    determinization on the phone + word lattices. If --word-determinize is set
+    true, it then does a second pass of determinization on the word lattices by
+    calling DeterminizeLatticePruned(). If both are set to false, then it gives
+    a warning and copying the lattices without determinization.
+
+    Note: the point of doing first a phone-level determinization pass and then
+    a word-level determinization pass is that it allows us to determinize
+    deeper lattices without "failing early" and returning a too-small lattice
+    due to the max-mem constraint.  The result should be the same as word-level
+    determinization in general, but for deeper lattices it is a bit faster,
+    despite the fact that we now have two passes of determinization by default.
+*/
+template<class Weight, class IntType>
+bool DeterminizeLatticePhonePruned(
+    const kaldi::TransitionInformation &trans_model,
+    const ExpandedFst<ArcTpl<Weight> > &ifst,
+    double prune,
+    MutableFst<ArcTpl<CompactLatticeWeightTpl<Weight, IntType> > > *ofst,
+    DeterminizeLatticePhonePrunedOptions opts
+      = DeterminizeLatticePhonePrunedOptions());
+
+/** "Destructive" version of DeterminizeLatticePhonePruned() where the input
+    lattice might be changed.
+*/
+template<class Weight, class IntType>
+bool DeterminizeLatticePhonePruned(
+    const kaldi::TransitionInformation &trans_model,
+    MutableFst<ArcTpl<Weight> > *ifst,
+    double prune,
+    MutableFst<ArcTpl<CompactLatticeWeightTpl<Weight, IntType> > > *ofst,
+    DeterminizeLatticePhonePrunedOptions opts
+      = DeterminizeLatticePhonePrunedOptions());
+
+/** This function is a wrapper of DeterminizeLatticePhonePruned() that works for
+    Lattice type FSTs.  It simplifies the calling process by calling
+    TopSort() Invert() and ArcSort() for you.
+    Unlike other determinization routines, the function
+    requires "ifst" to have transition-id's on the input side and words on the
+    output side.
+    This function can be used as the top-level interface to all the determinization
+    code.
+*/
+bool DeterminizeLatticePhonePrunedWrapper(
+    const kaldi::TransitionInformation &trans_model,
+    MutableFst<kaldi::LatticeArc> *ifst,
+    double prune,
+    MutableFst<kaldi::CompactLatticeArc> *ofst,
+    DeterminizeLatticePhonePrunedOptions opts
+      = DeterminizeLatticePhonePrunedOptions());
+
+/// @} end "addtogroup fst_extensions"
+
+} // end namespace fst
+
+#endif

speechx/speechx/kaldi/lat/kaldi-lattice.cc

+// lat/kaldi-lattice.cc
+
+// Copyright 2009-2011     Microsoft Corporation
+//                2013     Johns Hopkins University (author: Daniel Povey)
+
+// See ../../COPYING for clarification regarding multiple authors
+//
+// 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
+//
+// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
+// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+// MERCHANTABLITY OR NON-INFRINGEMENT.
+// See the Apache 2 License for the specific language governing permissions and
+// limitations under the License.
+
+
+#include "lat/kaldi-lattice.h"
+#include "fst/script/print-impl.h"
+
+namespace kaldi {
+
+/// Converts lattice types if necessary, deleting its input.
+template<class OrigWeightType>
+CompactLattice* ConvertToCompactLattice(fst::VectorFst<OrigWeightType> *ifst) {
+  if (!ifst) return NULL;
+  CompactLattice *ofst = new CompactLattice();
+  ConvertLattice(*ifst, ofst);
+  delete ifst;
+  return ofst;
+}
+
+// This overrides the template if there is no type conversion going on
+// (for efficiency).
+template<>
+CompactLattice* ConvertToCompactLattice(CompactLattice *ifst) {
+  return ifst;
+}
+
+/// Converts lattice types if necessary, deleting its input.
+template<class OrigWeightType>
+Lattice* ConvertToLattice(fst::VectorFst<OrigWeightType> *ifst) {
+  if (!ifst) return NULL;
+  Lattice *ofst = new Lattice();
+  ConvertLattice(*ifst, ofst);
+  delete ifst;
+  return ofst;
+}
+
+// This overrides the template if there is no type conversion going on
+// (for efficiency).
+template<>
+Lattice* ConvertToLattice(Lattice *ifst) {
+  return ifst;
+}
+
+
+bool WriteCompactLattice(std::ostream &os, bool binary,
+                         const CompactLattice &t) {
+  if (binary) {
+    fst::FstWriteOptions opts;
+    // Leave all the options default.  Normally these lattices wouldn't have any
+    // osymbols/isymbols so no point directing it not to write them (who knows what
+    // we'd want to if we had them).
+    return t.Write(os, opts);
+  } else {
+    // Text-mode output.  Note: we expect that t.InputSymbols() and
+    // t.OutputSymbols() would always return NULL.  The corresponding input
+    // routine would not work if the FST actually had symbols attached.
+    // Write a newline after the key, so the first line of the FST appears
+    // on its own line.
+    os << '\n';
+    bool acceptor = true, write_one = false;
+    fst::FstPrinter<CompactLatticeArc> printer(t, t.InputSymbols(),
+                                               t.OutputSymbols(),
+                                               NULL, acceptor, write_one, "\t");
+    printer.Print(&os, "<unknown>");
+    if (os.fail())
+      KALDI_WARN << "Stream failure detected.";
+    // Write another newline as a terminating character.  The read routine will
+    // detect this [this is a Kaldi mechanism, not somethig in the original
+    // OpenFst code].
+    os << '\n';
+    return os.good();
+  }
+}
+
+/// LatticeReader provides (static) functions for reading both Lattice
+/// and CompactLattice, in text form.
+class LatticeReader {
+  typedef LatticeArc Arc;
+  typedef LatticeWeight Weight;
+  typedef CompactLatticeArc CArc;
+  typedef CompactLatticeWeight CWeight;
+  typedef Arc::Label Label;
+  typedef Arc::StateId StateId;
+ public:
+  // everything is static in this class.
+
+  /** This function reads from the FST text format; it does not know in advance
+      whether it's a Lattice or CompactLattice in the stream so it tries to
+      read both formats until it becomes clear which is the correct one.
+  */
+  static std::pair<Lattice*, CompactLattice*> ReadText(
+      std::istream &is) {
+    typedef std::pair<Lattice*, CompactLattice*> PairT;
+    using std::string;
+    using std::vector;
+    Lattice *fst = new Lattice();
+    CompactLattice *cfst = new CompactLattice();
+    string line;
+    size_t nline = 0;
+    string separator = FLAGS_fst_field_separator + "\r\n";
+    while (std::getline(is, line)) {
+      nline++;
+      vector<string> col;
+      // on Windows we'll write in text and read in binary mode.
+      SplitStringToVector(line, separator.c_str(), true, &col);
+      if (col.size() == 0) break; // Empty line is a signal to stop, in our
+      // archive format.
+      if (col.size() > 5) {
+        KALDI_WARN << "Reading lattice: bad line in FST: " << line;
+        delete fst;
+        delete cfst;
+        return PairT(static_cast<Lattice*>(NULL),
+                     static_cast<CompactLattice*>(NULL));
+      }
+      StateId s;
+      if (!ConvertStringToInteger(col[0], &s)) {
+        KALDI_WARN << "FstCompiler: bad line in FST: " << line;
+        delete fst;
+        delete cfst;
+        return PairT(static_cast<Lattice*>(NULL),
+                     static_cast<CompactLattice*>(NULL));
+      }
+      if (fst)
+        while (s >= fst->NumStates())
+          fst->AddState();
+      if (cfst)
+        while (s >= cfst->NumStates())
+          cfst->AddState();
+      if (nline == 1) {
+        if (fst) fst->SetStart(s);
+        if (cfst) cfst->SetStart(s);
+      }
+
+      if (fst) { // we still have fst; try to read that arc.
+        bool ok = true;
+        Arc arc;
+        Weight w;
+        StateId d = s;
+        switch (col.size()) {
+          case 1 :
+            fst->SetFinal(s, Weight::One());
+            break;
+          case 2:
+            if (!StrToWeight(col[1], true, &w)) ok = false;
+            else fst->SetFinal(s, w);
+            break;
+          case 3: // 3 columns not ok for Lattice format; it's not an acceptor.
+            ok = false;
+            break;
+          case 4:
+            ok = ConvertStringToInteger(col[1], &arc.nextstate) &&
+                ConvertStringToInteger(col[2], &arc.ilabel) &&
+                ConvertStringToInteger(col[3], &arc.olabel);
+            if (ok) {
+              d = arc.nextstate;
+              arc.weight = Weight::One();
+              fst->AddArc(s, arc);
+            }
+            break;
+          case 5:
+            ok = ConvertStringToInteger(col[1], &arc.nextstate) &&
+                ConvertStringToInteger(col[2], &arc.ilabel) &&
+                ConvertStringToInteger(col[3], &arc.olabel) &&
+                StrToWeight(col[4], false, &arc.weight);
+            if (ok) {
+              d = arc.nextstate;
+              fst->AddArc(s, arc);
+            }
+            break;
+          default:
+            ok = false;
+        }
+        while (d >= fst->NumStates())
+          fst->AddState();
+        if (!ok) {
+          delete fst;
+          fst = NULL;
+        }
+      }
+      if (cfst) {
+        bool ok = true;
+        CArc arc;
+        CWeight w;
+        StateId d = s;
+        switch (col.size()) {
+          case 1 :
+            cfst->SetFinal(s, CWeight::One());
+            break;
+          case 2:
+            if (!StrToCWeight(col[1], true, &w)) ok = false;
+            else cfst->SetFinal(s, w);
+            break;
+          case 3: // compact-lattice is acceptor format: state, next-state, label.
+            ok = ConvertStringToInteger(col[1], &arc.nextstate) &&
+                ConvertStringToInteger(col[2], &arc.ilabel);
+            if (ok) {
+              d = arc.nextstate;
+              arc.olabel = arc.ilabel;
+              arc.weight = CWeight::One();
+              cfst->AddArc(s, arc);
+            }
+            break;
+          case 4:
+            ok = ConvertStringToInteger(col[1], &arc.nextstate) &&
+                ConvertStringToInteger(col[2], &arc.ilabel) &&
+                StrToCWeight(col[3], false, &arc.weight);
+            if (ok) {
+              d = arc.nextstate;
+              arc.olabel = arc.ilabel;
+              cfst->AddArc(s, arc);
+            }
+            break;
+          case 5: default:
+            ok = false;
+        }
+        while (d >= cfst->NumStates())
+          cfst->AddState();
+        if (!ok) {
+          delete cfst;
+          cfst = NULL;
+        }
+      }
+      if (!fst && !cfst) {
+        KALDI_WARN << "Bad line in lattice text format: " << line;
+        // read until we get an empty line, so at least we
+        // have a chance to read the next one (although this might
+        // be a bit futile since the calling code will get unhappy
+        // about failing to read this one.
+        while (std::getline(is, line)) {
+          SplitStringToVector(line, separator.c_str(), true, &col);
+          if (col.empty()) break;
+        }
+        return PairT(static_cast<Lattice*>(NULL),
+                     static_cast<CompactLattice*>(NULL));
+      }
+    }
+    return PairT(fst, cfst);
+  }
+
+  static bool StrToWeight(const std::string &s, bool allow_zero, Weight *w) {
+    std::istringstream strm(s);
+    strm >> *w;
+    if (!strm || (!allow_zero && *w == Weight::Zero())) {
+      return false;
+    }
+    return true;
+  }
+
+  static  bool StrToCWeight(const std::string &s, bool allow_zero, CWeight *w) {
+    std::istringstream strm(s);
+    strm >> *w;
+    if (!strm || (!allow_zero && *w == CWeight::Zero())) {
+      return false;
+    }
+    return true;
+  }
+};
+
+
+CompactLattice *ReadCompactLatticeText(std::istream &is) {
+  std::pair<Lattice*, CompactLattice*> lat_pair = LatticeReader::ReadText(is);
+  if (lat_pair.second != NULL) {
+    delete lat_pair.first;
+    return lat_pair.second;
+  } else if (lat_pair.first != NULL) {
+    // note: ConvertToCompactLattice frees its input.
+    return ConvertToCompactLattice(lat_pair.first);
+  } else {
+    return NULL;
+  }
+}
+
+
+Lattice *ReadLatticeText(std::istream &is) {
+  std::pair<Lattice*, CompactLattice*> lat_pair = LatticeReader::ReadText(is);
+  if (lat_pair.first != NULL) {
+    delete lat_pair.second;
+    return lat_pair.first;
+  } else if (lat_pair.second != NULL) {
+    // note: ConvertToLattice frees its input.
+    return ConvertToLattice(lat_pair.second);
+  } else {
+    return NULL;
+  }
+}
+
+bool ReadCompactLattice(std::istream &is, bool binary,
+                        CompactLattice **clat) {
+  KALDI_ASSERT(*clat == NULL);
+  if (binary) {
+    fst::FstHeader hdr;
+    if (!hdr.Read(is, "<unknown>")) {
+      KALDI_WARN << "Reading compact lattice: error reading FST header.";
+      return false;
+    }
+    if (hdr.FstType() != "vector") {
+      KALDI_WARN << "Reading compact lattice: unsupported FST type: "
+                 << hdr.FstType();
+      return false;
+    }
+    fst::FstReadOptions ropts("<unspecified>",
+                              &hdr);
+
+    typedef fst::CompactLatticeWeightTpl<fst::LatticeWeightTpl<float>, int32> T1;
+    typedef fst::CompactLatticeWeightTpl<fst::LatticeWeightTpl<double>, int32> T2;
+    typedef fst::LatticeWeightTpl<float> T3;
+    typedef fst::LatticeWeightTpl<double> T4;
+    typedef fst::VectorFst<fst::ArcTpl<T1> > F1;
+    typedef fst::VectorFst<fst::ArcTpl<T2> > F2;
+    typedef fst::VectorFst<fst::ArcTpl<T3> > F3;
+    typedef fst::VectorFst<fst::ArcTpl<T4> > F4;
+
+    CompactLattice *ans = NULL;
+    if (hdr.ArcType() == T1::Type()) {
+      ans = ConvertToCompactLattice(F1::Read(is, ropts));
+    } else if (hdr.ArcType() == T2::Type()) {
+      ans = ConvertToCompactLattice(F2::Read(is, ropts));
+    } else if (hdr.ArcType() == T3::Type()) {
+      ans = ConvertToCompactLattice(F3::Read(is, ropts));
+    } else if (hdr.ArcType() == T4::Type()) {
+      ans = ConvertToCompactLattice(F4::Read(is, ropts));
+    } else {
+      KALDI_WARN << "FST with arc type " << hdr.ArcType()
+                 << " cannot be converted to CompactLattice.\n";
+      return false;
+    }
+    if (ans == NULL) {
+      KALDI_WARN << "Error reading compact lattice (after reading header).";
+      return false;
+    }
+    *clat = ans;
+    return true;
+  } else {
+    // The next line would normally consume the \r on Windows, plus any
+    // extra spaces that might have got in there somehow.
+    while (std::isspace(is.peek()) && is.peek() != '\n') is.get();
+    if (is.peek() == '\n') is.get(); // consume the newline.
+    else { // saw spaces but no newline.. this is not expected.
+      KALDI_WARN << "Reading compact lattice: unexpected sequence of spaces "
+                 << " at file position " << is.tellg();
+      return false;
+    }
+    *clat = ReadCompactLatticeText(is); // that routine will warn on error.
+    return (*clat != NULL);
+  }
+}
+
+
+bool CompactLatticeHolder::Read(std::istream &is) {
+  Clear(); // in case anything currently stored.
+  int c = is.peek();
+  if (c == -1) {
+    KALDI_WARN << "End of stream detected reading CompactLattice.";
+    return false;
+  } else if (isspace(c)) { // The text form of the lattice begins
+    // with space (normally, '\n'), so this means it's text (the binary form
+    // cannot begin with space because it starts with the FST Type() which is not
+    // space).
+    return ReadCompactLattice(is, false, &t_);
+  } else if (c != 214) { // 214 is first char of FST magic number,
+    // on little-endian machines which is all we support (\326 octal)
+    KALDI_WARN << "Reading compact lattice: does not appear to be an FST "
+               << " [non-space but no magic number detected], file pos is "
+               << is.tellg();
+    return false;
+  } else {
+    return ReadCompactLattice(is, true, &t_);
+  }
+}
+
+bool WriteLattice(std::ostream &os, bool binary, const Lattice &t) {
+  if (binary) {
+    fst::FstWriteOptions opts;
+    // Leave all the options default.  Normally these lattices wouldn't have any
+    // osymbols/isymbols so no point directing it not to write them (who knows what
+    // we'd want to do if we had them).
+    return t.Write(os, opts);
+  } else {
+    // Text-mode output.  Note: we expect that t.InputSymbols() and
+    // t.OutputSymbols() would always return NULL.  The corresponding input
+    // routine would not work if the FST actually had symbols attached.
+    // Write a newline after the key, so the first line of the FST appears
+    // on its own line.
+    os << '\n';
+    bool acceptor = false, write_one = false;
+    fst::FstPrinter<LatticeArc> printer(t, t.InputSymbols(),
+                                        t.OutputSymbols(),
+                                        NULL, acceptor, write_one, "\t");
+    printer.Print(&os, "<unknown>");
+    if (os.fail())
+      KALDI_WARN << "Stream failure detected.";
+    // Write another newline as a terminating character.  The read routine will
+    // detect this [this is a Kaldi mechanism, not somethig in the original
+    // OpenFst code].
+    os << '\n';
+    return os.good();
+  }
+}
+
+bool ReadLattice(std::istream &is, bool binary,
+                 Lattice **lat) {
+  KALDI_ASSERT(*lat == NULL);
+  if (binary) {
+    fst::FstHeader hdr;
+    if (!hdr.Read(is, "<unknown>")) {
+      KALDI_WARN << "Reading lattice: error reading FST header.";
+      return false;
+    }
+    if (hdr.FstType() != "vector") {
+      KALDI_WARN << "Reading lattice: unsupported FST type: "
+                 << hdr.FstType();
+      return false;
+    }
+    fst::FstReadOptions ropts("<unspecified>",
+                              &hdr);
+
+    typedef fst::CompactLatticeWeightTpl<fst::LatticeWeightTpl<float>, int32> T1;
+    typedef fst::CompactLatticeWeightTpl<fst::LatticeWeightTpl<double>, int32> T2;
+    typedef fst::LatticeWeightTpl<float> T3;
+    typedef fst::LatticeWeightTpl<double> T4;
+    typedef fst::VectorFst<fst::ArcTpl<T1> > F1;
+    typedef fst::VectorFst<fst::ArcTpl<T2> > F2;
+    typedef fst::VectorFst<fst::ArcTpl<T3> > F3;
+    typedef fst::VectorFst<fst::ArcTpl<T4> > F4;
+
+    Lattice *ans = NULL;
+    if (hdr.ArcType() == T1::Type()) {
+      ans = ConvertToLattice(F1::Read(is, ropts));
+    } else if (hdr.ArcType() == T2::Type()) {
+      ans = ConvertToLattice(F2::Read(is, ropts));
+    } else if (hdr.ArcType() == T3::Type()) {
+      ans = ConvertToLattice(F3::Read(is, ropts));
+    } else if (hdr.ArcType() == T4::Type()) {
+      ans = ConvertToLattice(F4::Read(is, ropts));
+    } else {
+      KALDI_WARN << "FST with arc type " << hdr.ArcType()
+                 << " cannot be converted to Lattice.\n";
+      return false;
+    }
+    if (ans == NULL) {
+      KALDI_WARN << "Error reading lattice (after reading header).";
+      return false;
+    }
+    *lat = ans;
+    return true;
+  } else {
+    // The next line would normally consume the \r on Windows, plus any
+    // extra spaces that might have got in there somehow.
+    while (std::isspace(is.peek()) && is.peek() != '\n') is.get();
+    if (is.peek() == '\n') is.get(); // consume the newline.
+    else { // saw spaces but no newline.. this is not expected.
+      KALDI_WARN << "Reading compact lattice: unexpected sequence of spaces "
+                 << " at file position " << is.tellg();
+      return false;
+    }
+    *lat = ReadLatticeText(is); // that routine will warn on error.
+    return (*lat != NULL);
+  }
+}
+
+
+/* Since we don't write the binary headers for this type of holder,
+   we use a different method to work out whether we're in binary mode.
+ */
+bool LatticeHolder::Read(std::istream &is) {
+  Clear(); // in case anything currently stored.
+  int c = is.peek();
+  if (c == -1) {
+    KALDI_WARN << "End of stream detected reading Lattice.";
+    return false;
+  } else if (isspace(c)) { // The text form of the lattice begins
+    // with space (normally, '\n'), so this means it's text (the binary form
+    // cannot begin with space because it starts with the FST Type() which is not
+    // space).
+    return ReadLattice(is, false, &t_);
+  } else if (c != 214) { // 214 is first char of FST magic number,
+    // on little-endian machines which is all we support (\326 octal)
+    KALDI_WARN << "Reading compact lattice: does not appear to be an FST "
+               << " [non-space but no magic number detected], file pos is "
+               << is.tellg();
+    return false;
+  } else {
+    return ReadLattice(is, true, &t_);
+  }
+}
+
+
+
+} // end namespace kaldi

speechx/speechx/kaldi/lat/kaldi-lattice.h

+// lat/kaldi-lattice.h
+
+// Copyright 2009-2011  Microsoft Corporation
+
+// See ../../COPYING for clarification regarding multiple authors
+//
+// 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
+//
+// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
+// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+// MERCHANTABLITY OR NON-INFRINGEMENT.
+// See the Apache 2 License for the specific language governing permissions and
+// limitations under the License.
+
+
+#ifndef KALDI_LAT_KALDI_LATTICE_H_
+#define KALDI_LAT_KALDI_LATTICE_H_
+
+#include "fstext/fstext-lib.h"
+#include "base/kaldi-common.h"
+#include "util/common-utils.h"
+
+
+namespace kaldi {
+// will import some things above...
+
+typedef fst::LatticeWeightTpl<BaseFloat> LatticeWeight;
+
+// careful: kaldi::int32 is not always the same C type as fst::int32
+typedef fst::CompactLatticeWeightTpl<LatticeWeight, int32> CompactLatticeWeight;
+
+typedef fst::CompactLatticeWeightCommonDivisorTpl<LatticeWeight, int32>
+  CompactLatticeWeightCommonDivisor;
+
+typedef fst::ArcTpl<LatticeWeight> LatticeArc;
+
+typedef fst::ArcTpl<CompactLatticeWeight> CompactLatticeArc;
+
+typedef fst::VectorFst<LatticeArc> Lattice;
+
+typedef fst::VectorFst<CompactLatticeArc> CompactLattice;
+
+// The following functions for writing and reading lattices in binary or text
+// form are provided here in case you need to include lattices in larger,
+// Kaldi-type objects with their own Read and Write functions.  Caution: these
+// functions return false on stream failure rather than throwing an exception as
+// most similar Kaldi functions would do.
+
+bool WriteCompactLattice(std::ostream &os, bool binary,
+                         const CompactLattice &clat);
+bool WriteLattice(std::ostream &os, bool binary,
+                  const Lattice &lat);
+
+// the following function requires that *clat be
+// NULL when called.
+bool ReadCompactLattice(std::istream &is, bool binary,
+                        CompactLattice **clat);
+// the following function requires that *lat be
+// NULL when called.
+bool ReadLattice(std::istream &is, bool binary,
+                 Lattice **lat);
+
+
+class CompactLatticeHolder {
+ public:
+  typedef CompactLattice T;
+
+  CompactLatticeHolder() { t_ = NULL; }
+
+  static bool Write(std::ostream &os, bool binary, const T &t) {
+    // Note: we don't include the binary-mode header when writing
+    // this object to disk; this ensures that if we write to single
+    // files, the result can be read by OpenFst.
+    return WriteCompactLattice(os, binary, t);
+  }
+
+  bool Read(std::istream &is);
+
+  static bool IsReadInBinary() { return true; }
+
+  T &Value() {
+    KALDI_ASSERT(t_ != NULL && "Called Value() on empty CompactLatticeHolder");
+    return *t_;
+  }
+
+  void Clear() { delete t_; t_ = NULL; }
+
+  void Swap(CompactLatticeHolder *other) {
+    std::swap(t_, other->t_);
+  }
+
+  bool ExtractRange(const CompactLatticeHolder &other, const std::string &range) {
+    KALDI_ERR << "ExtractRange is not defined for this type of holder.";
+    return false;
+  }
+
+  ~CompactLatticeHolder() { Clear(); }
+ private:
+  T *t_;
+};
+
+class LatticeHolder {
+ public:
+  typedef Lattice T;
+
+  LatticeHolder() { t_ = NULL; }
+
+  static bool Write(std::ostream &os, bool binary, const T &t) {
+    // Note: we don't include the binary-mode header when writing
+    // this object to disk; this ensures that if we write to single
+    // files, the result can be read by OpenFst.
+    return WriteLattice(os, binary, t);
+  }
+
+  bool Read(std::istream &is);
+
+  static bool IsReadInBinary() { return true; }
+
+  T &Value() {
+    KALDI_ASSERT(t_ != NULL && "Called Value() on empty LatticeHolder");
+    return *t_;
+  }
+
+  void Clear() {  delete t_; t_ = NULL; }
+
+  void Swap(LatticeHolder *other) {
+    std::swap(t_, other->t_);
+  }
+
+  bool ExtractRange(const LatticeHolder &other, const std::string &range) {
+    KALDI_ERR << "ExtractRange is not defined for this type of holder.";
+    return false;
+  }
+
+  ~LatticeHolder() { Clear(); }
+ private:
+  T *t_;
+};
+
+typedef TableWriter<LatticeHolder> LatticeWriter;
+typedef SequentialTableReader<LatticeHolder> SequentialLatticeReader;
+typedef RandomAccessTableReader<LatticeHolder> RandomAccessLatticeReader;
+
+typedef TableWriter<CompactLatticeHolder> CompactLatticeWriter;
+typedef SequentialTableReader<CompactLatticeHolder> SequentialCompactLatticeReader;
+typedef RandomAccessTableReader<CompactLatticeHolder> RandomAccessCompactLatticeReader;
+
+
+} // namespace kaldi
+
+#endif  // KALDI_LAT_KALDI_LATTICE_H_