// See www.openfst.org for extensive documentation on this weighted
  // finite-state transducer library.
  
  #include <fst/script/text-io.h>
  
  #include <cstring>
  #include <fstream>
  #include <ostream>
  #include <sstream>
  #include <utility>
  
  #include <fst/log.h>
  #include <fstream>
  #include <fst/util.h>
  
  namespace fst {
  namespace script {
  
  // Reads vector of weights; returns true on success.
  bool ReadPotentials(const string &weight_type, const string &filename,
                      std::vector<WeightClass> *potentials) {
    std::ifstream istrm(filename);
    if (!istrm.good()) {
      LOG(ERROR) << "ReadPotentials: Can't open file: " << filename;
      return false;
    }
    static constexpr int kLineLen = 8096;
    char line[kLineLen];
    size_t nline = 0;
    potentials->clear();
    while (!istrm.getline(line, kLineLen).fail()) {
      ++nline;
      std::vector<char *> col;
      SplitString(line, "
  \t ", &col, true);
      if (col.empty() || col[0][0] == '\0') continue;
      if (col.size() != 2) {
        FSTERROR() << "ReadPotentials: Bad number of columns, "
                   << "file = " << filename << ", line = " << nline;
        return false;
      }
      const ssize_t s = StrToInt64(col[0], filename, nline, false);
      const WeightClass weight(weight_type, col[1]);
      while (potentials->size() <= s) {
        potentials->push_back(WeightClass::Zero(weight_type));
      }
      potentials->back() = weight;
    }
    return true;
  }
  
  // Writes vector of weights; returns true on success.
  bool WritePotentials(const string &filename,
                       const std::vector<WeightClass> &potentials) {
    std::ofstream ostrm;
    if (!filename.empty()) {
      ostrm.open(filename);
      if (!ostrm.good()) {
        LOG(ERROR) << "WritePotentials: Can't open file: " << filename;
        return false;
      }
    }
    std::ostream &strm = ostrm.is_open() ? ostrm : std::cout;
    strm.precision(9);
    for (size_t s = 0; s < potentials.size(); ++s) {
      strm << s << "\t" << potentials[s] << "
  ";
    }
    if (strm.fail()) {
      LOG(ERROR) << "WritePotentials: Write failed: "
                 << (filename.empty() ? "standard output" : filename);
      return false;
    }
    return true;
  }
  
  }  // namespace script
  }  // namespace fst