// 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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// Converts an RTN represented by FSTs and non-terminal labels into a PDT.
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#include <cstring>
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#include <string>
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#include <vector>
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#include <fst/flags.h>
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#include <fst/extensions/pdt/getters.h>
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#include <fst/extensions/pdt/pdtscript.h>
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#include <fst/util.h>
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#include <fst/vector-fst.h>
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DEFINE_string(pdt_parentheses, "", "PDT parenthesis label pairs");
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DEFINE_string(pdt_parser_type, "left",
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"Construction method, one of: \"left\", \"left_sr\"");
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DEFINE_int64(start_paren_labels, fst::kNoLabel,
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"Index to use for the first inserted parentheses; if not "
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"specified, the next available label beyond the highest output "
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"label is used");
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DEFINE_string(left_paren_prefix, "(_", "Prefix to attach to SymbolTable "
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"labels for inserted left parentheses");
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DEFINE_string(right_paren_prefix, ")_", "Prefix to attach to SymbolTable "
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"labels for inserted right parentheses");
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void Cleanup(std::vector<fst::script::LabelFstClassPair> *pairs) {
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for (const auto &pair : *pairs) {
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delete pair.second;
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}
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pairs->clear();
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}
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int main(int argc, char **argv) {
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namespace s = fst::script;
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using fst::script::FstClass;
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using fst::script::VectorFstClass;
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using fst::PdtParserType;
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using fst::WriteLabelPairs;
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string usage = "Converts an RTN represented by FSTs";
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usage += " and non-terminal labels into PDT.\n\n Usage: ";
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usage += argv[0];
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usage += " root.fst rootlabel [rule1.fst label1 ...] [out.fst]\n";
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std::set_new_handler(FailedNewHandler);
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SET_FLAGS(usage.c_str(), &argc, &argv, true);
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if (argc < 4) {
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ShowUsage();
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return 1;
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}
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const string in_name = argv[1];
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const string out_name = argc % 2 == 0 ? argv[argc - 1] : "";
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auto *ifst = FstClass::Read(in_name);
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if (!ifst) return 1;
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PdtParserType parser_type;
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if (!s::GetPdtParserType(FLAGS_pdt_parser_type, &parser_type)) {
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LOG(ERROR) << argv[0] << ": Unknown PDT parser type: "
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<< FLAGS_pdt_parser_type;
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delete ifst;
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return 1;
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}
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std::vector<s::LabelFstClassPair> pairs;
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// Note that if the root label is beyond the range of the underlying FST's
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// labels, truncation will occur.
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const auto root = atoll(argv[2]);
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pairs.emplace_back(root, ifst);
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for (auto i = 3; i < argc - 1; i += 2) {
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ifst = FstClass::Read(argv[i]);
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if (!ifst) {
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Cleanup(&pairs);
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return 1;
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}
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// Note that if the root label is beyond the range of the underlying FST's
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// labels, truncation will occur.
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const auto label = atoll(argv[i + 1]);
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pairs.emplace_back(label, ifst);
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}
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VectorFstClass ofst(ifst->ArcType());
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std::vector<s::LabelPair> parens;
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s::PdtReplace(pairs, &ofst, &parens, root, parser_type,
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FLAGS_start_paren_labels, FLAGS_left_paren_prefix,
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FLAGS_right_paren_prefix);
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Cleanup(&pairs);
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if (!FLAGS_pdt_parentheses.empty()) {
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if (!WriteLabelPairs(FLAGS_pdt_parentheses, parens)) return 1;
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}
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ofst.Write(out_name);
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return 0;
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}
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