// See www.openfst.org for extensive documentation on this weighted
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// finite-state transducer library.
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//
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// Stand-alone class to print out binary FSTs in the AT&T format, a helper
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// class for fstprint.cc.
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#ifndef FST_SCRIPT_PRINT_IMPL_H_
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#define FST_SCRIPT_PRINT_IMPL_H_
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#include <ostream>
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#include <sstream>
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#include <string>
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#include <fst/fstlib.h>
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#include <fst/util.h>
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DECLARE_string(fst_field_separator);
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namespace fst {
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// Print a binary FST in textual format (helper class for fstprint.cc).
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// WARNING: Stand-alone use of this class not recommended, most code should
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// read/write using the binary format which is much more efficient.
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template <class Arc>
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class FstPrinter {
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public:
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using StateId = typename Arc::StateId;
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using Label = typename Arc::Label;
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using Weight = typename Arc::Weight;
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FstPrinter(const Fst<Arc> &fst, const SymbolTable *isyms,
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const SymbolTable *osyms, const SymbolTable *ssyms, bool accep,
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bool show_weight_one, const string &field_separator,
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const string &missing_symbol = "")
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: fst_(fst),
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isyms_(isyms),
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osyms_(osyms),
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ssyms_(ssyms),
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accep_(accep && fst.Properties(kAcceptor, true)),
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ostrm_(nullptr),
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show_weight_one_(show_weight_one),
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sep_(field_separator),
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missing_symbol_(missing_symbol) {}
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// Prints FST to an output stream.
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void Print(std::ostream *ostrm, const string &dest) {
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ostrm_ = ostrm;
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dest_ = dest;
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const auto start = fst_.Start();
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if (start == kNoStateId) return;
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// Initial state first.
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PrintState(start);
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for (StateIterator<Fst<Arc>> siter(fst_); !siter.Done(); siter.Next()) {
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const auto s = siter.Value();
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if (s != start) PrintState(s);
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}
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}
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private:
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void PrintId(StateId id, const SymbolTable *syms, const char *name) const {
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if (syms) {
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string symbol = syms->Find(id);
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if (symbol.empty()) {
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if (missing_symbol_.empty()) {
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FSTERROR() << "FstPrinter: Integer " << id
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<< " is not mapped to any textual symbol"
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<< ", symbol table = " << syms->Name()
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<< ", destination = " << dest_;
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symbol = "?";
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} else {
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symbol = missing_symbol_;
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}
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}
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*ostrm_ << symbol;
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} else {
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*ostrm_ << id;
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}
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}
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void PrintStateId(StateId s) const { PrintId(s, ssyms_, "state ID"); }
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void PrintILabel(Label l) const { PrintId(l, isyms_, "arc input label"); }
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void PrintOLabel(Label l) const { PrintId(l, osyms_, "arc output label"); }
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void PrintState(StateId s) const {
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bool output = false;
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for (ArcIterator<Fst<Arc>> aiter(fst_, s); !aiter.Done(); aiter.Next()) {
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const auto &arc = aiter.Value();
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PrintStateId(s);
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*ostrm_ << sep_;
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PrintStateId(arc.nextstate);
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*ostrm_ << sep_;
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PrintILabel(arc.ilabel);
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if (!accep_) {
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*ostrm_ << sep_;
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PrintOLabel(arc.olabel);
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}
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if (show_weight_one_ || arc.weight != Weight::One())
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*ostrm_ << sep_ << arc.weight;
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*ostrm_ << "\n";
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output = true;
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}
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const auto weight = fst_.Final(s);
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if (weight != Weight::Zero() || !output) {
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PrintStateId(s);
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if (show_weight_one_ || weight != Weight::One()) {
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*ostrm_ << sep_ << weight;
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}
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*ostrm_ << "\n";
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}
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}
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const Fst<Arc> &fst_;
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const SymbolTable *isyms_; // ilabel symbol table.
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const SymbolTable *osyms_; // olabel symbol table.
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const SymbolTable *ssyms_; // slabel symbol table.
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bool accep_; // Print as acceptor when possible?
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std::ostream *ostrm_; // Text FST destination.
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string dest_; // Text FST destination name.
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bool show_weight_one_; // Print weights equal to Weight::One()?
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string sep_; // Separator character between fields.
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string missing_symbol_; // Symbol to print when lookup fails (default
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// "" means raise error).
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//
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FstPrinter(const FstPrinter &) = delete;
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FstPrinter &operator=(const FstPrinter &) = delete;
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};
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} // namespace fst
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#endif // FST_SCRIPT_PRINT_IMPL_H_
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