src/include/fst/script/print-impl.h

// print.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: riley@google.com (Michael Riley)
//
// \file
// Stand-alone class to print out binary FSTs in the AT&T format,
// helper class for fstprint.cc

#ifndef FST_SCRIPT_PRINT_IMPL_H_
#define FST_SCRIPT_PRINT_IMPL_H_

#include <sstream>
#include <string>

#include <fst/fst.h>
#include <fst/util.h>

DECLARE_string(fst_field_separator);

namespace fst {

// Print a binary Fst in textual format, helper class for fstprint.cc
// WARNING: Stand-alone use of this class not recommended, most code should
// read/write using the binary format which is much more efficient.
template <class A> class FstPrinter {
 public:
  typedef A Arc;
  typedef typename A::StateId StateId;
  typedef typename A::Label Label;
  typedef typename A::Weight Weight;

  FstPrinter(const Fst<A> &fst,
             const SymbolTable *isyms,
             const SymbolTable *osyms,
             const SymbolTable *ssyms,
             bool accep,
             bool show_weight_one)
      : fst_(fst), isyms_(isyms), osyms_(osyms), ssyms_(ssyms),
        accep_(accep && fst.Properties(kAcceptor, true)), ostrm_(0),
        show_weight_one_(show_weight_one) {}

  // Print Fst to an output stream
  void Print(ostream *ostrm, const string &dest) {
    ostrm_ = ostrm;
    dest_ = dest;
    StateId start = fst_.Start();
    if (start == kNoStateId)
      return;
    // initial state first
    PrintState(start);
    for (StateIterator< Fst<A> > siter(fst_);
         !siter.Done();
         siter.Next()) {
      StateId s = siter.Value();
      if (s != start)
        PrintState(s);
    }
  }

 private:
  // Maximum line length in text file.
  static const int kLineLen = 8096;

  void PrintId(int64 id, const SymbolTable *syms,
               const char *name) const {
    if (syms) {
      string symbol = syms->Find(id);
      if (symbol == "") {
        FSTERROR() << "FstPrinter: Integer " << id
                   << " is not mapped to any textual symbol"
                   << ", symbol table = " << syms->Name()
                   << ", destination = " << dest_;
        symbol = "?";
      }
      *ostrm_ << symbol;
    } else {
      *ostrm_ << id;
    }
  }

  void PrintStateId(StateId s) const {
     PrintId(s, ssyms_, "state ID");
  }

  void PrintILabel(Label l) const {
     PrintId(l, isyms_, "arc input label");
  }

  void PrintOLabel(Label l) const {
     PrintId(l, osyms_, "arc output label");
  }

  void PrintState(StateId s) const {
    bool output = false;
    for (ArcIterator< Fst<A> > aiter(fst_, s);
         !aiter.Done();
         aiter.Next()) {
      Arc arc = aiter.Value();
      PrintStateId(s);
      *ostrm_ << FLAGS_fst_field_separator[0];
      PrintStateId(arc.nextstate);
      *ostrm_ << FLAGS_fst_field_separator[0];
      PrintILabel(arc.ilabel);
      if (!accep_) {
        *ostrm_ << FLAGS_fst_field_separator[0];
        PrintOLabel(arc.olabel);
      }
      if (show_weight_one_ || arc.weight != Weight::One())
        *ostrm_ << FLAGS_fst_field_separator[0] << arc.weight;
      *ostrm_ << "\n";
      output = true;
    }
    Weight final = fst_.Final(s);
    if (final != Weight::Zero() || !output) {
      PrintStateId(s);
      if (show_weight_one_ || final != Weight::One()) {
        *ostrm_ << FLAGS_fst_field_separator[0] << final;
      }
      *ostrm_ << "\n";
    }
  }

  const Fst<A> &fst_;
  const SymbolTable *isyms_;     // ilabel symbol table
  const SymbolTable *osyms_;     // olabel symbol table
  const SymbolTable *ssyms_;     // slabel symbol table
  bool accep_;                   // print as acceptor when possible
  ostream *ostrm_;               // text FST destination
  string dest_;                  // text FST destination name
  bool show_weight_one_;         // print weights equal to Weight::One()
  DISALLOW_COPY_AND_ASSIGN(FstPrinter);
};

}  // namespace fst

#endif  // FST_SCRIPT_PRINT_IMPL_H_