Add HLG decoding for streaming CTC models (#731)

sherpa-onnx/csrc/online-ctc-decoder.h

@@ -5,12 +5,16 @@
 #ifndef SHERPA_ONNX_CSRC_ONLINE_CTC_DECODER_H_
 #define SHERPA_ONNX_CSRC_ONLINE_CTC_DECODER_H_
 
+#include <memory>
 #include <vector>
 
+#include "kaldi-decoder/csrc/faster-decoder.h"
 #include "onnxruntime_cxx_api.h"  // NOLINT
 
 namespace sherpa_onnx {
 
+class OnlineStream;
+
 struct OnlineCtcDecoderResult {
   /// Number of frames after subsampling we have decoded so far
   int32_t frame_offset = 0;
@@ -37,7 +41,13 @@ class OnlineCtcDecoder {
    * @param  results Input & Output parameters..
    */
   virtual void Decode(Ort::Value log_probs,
-                      std::vector<OnlineCtcDecoderResult> *results) = 0;
+                      std::vector<OnlineCtcDecoderResult> *results,
+                      OnlineStream **ss = nullptr, int32_t n = 0) = 0;
+
+  virtual std::unique_ptr<kaldi_decoder::FasterDecoder> CreateFasterDecoder()
+      const {
+    return nullptr;
+  }
 };
 
 }  // namespace sherpa_onnx