// 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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// Performs the dynamic replacement of arcs in one FST with another FST,
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// allowing for the definition of FSTs analogous to RTNs.
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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/script/getters.h>
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#include <fst/script/replace.h>
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DECLARE_string(call_arc_labeling);
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DECLARE_string(return_arc_labeling);
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DECLARE_int64(return_label);
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DECLARE_bool(epsilon_on_replace);
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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 fstreplace_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::ReplaceLabelType;
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string usage = "Recursively replaces FST arcs with other FST(s).\n\n"
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" 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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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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ReplaceLabelType call_label_type;
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if (!s::GetReplaceLabelType(FLAGS_call_arc_labeling, FLAGS_epsilon_on_replace,
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&call_label_type)) {
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LOG(ERROR) << argv[0] << ": Unknown or unsupported call arc replace "
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<< "label type: " << FLAGS_call_arc_labeling;
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}
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ReplaceLabelType return_label_type;
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if (!s::GetReplaceLabelType(FLAGS_return_arc_labeling,
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FLAGS_epsilon_on_replace, &return_label_type)) {
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LOG(ERROR) << argv[0] << ": Unknown or unsupported return arc replace "
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<< "label type: " << FLAGS_return_arc_labeling;
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}
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s::ReplaceOptions opts(root, call_label_type, return_label_type,
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FLAGS_return_label);
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VectorFstClass ofst(ifst->ArcType());
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s::Replace(pairs, &ofst, opts);
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Cleanup(&pairs);
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return !ofst.Write(out_name);
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}
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