feat: add punctuation C++ API (#2510)

Co-authored-by: Aruxxxi <xiangcl@zhisuan.com>

@@ -30,6 +30,9 @@ target_link_libraries(sense-voice-cxx-api sherpa-onnx-cxx-api)
 add_executable(nemo-canary-cxx-api ./nemo-canary-cxx-api.cc)
 target_link_libraries(nemo-canary-cxx-api sherpa-onnx-cxx-api)
 
+add_executable(punctuation-cxx-api ./punctuation-cxx-api.cc)
+target_link_libraries(punctuation-cxx-api sherpa-onnx-cxx-api)
+
 if(SHERPA_ONNX_ENABLE_PORTAUDIO)
   add_executable(sense-voice-simulate-streaming-microphone-cxx-api
     ./sense-voice-simulate-streaming-microphone-cxx-api.cc

+// cxx-api-examples/punctuation-cxx-api.cc
+// Copyright (c)  2025  Xiaomi Corporation
+
+// To use punctuation model:
+// wget https://github.com/k2-fsa/sherpa-onnx/releases/download/punctuation-models/sherpa-onnx-punct-ct-transformer-zh-en-vocab272727-2024-04-12.tar.bz2
+// tar xvf sherpa-onnx-punct-ct-transformer-zh-en-vocab272727-2024-04-12.tar.bz2
+// rm sherpa-onnx-punct-ct-transformer-zh-en-vocab272727-2024-04-12.tar.bz2
+
+#include <iostream>
+#include <string>
+
+#include "sherpa-onnx/c-api/cxx-api.h"
+
+int32_t main() {
+  using namespace sherpa_onnx::cxx;  // NOLINT
+
+  OfflinePunctuationConfig punctuation_config;
+  punctuation_config.model.ct_transformer = "./sherpa-onnx-punct-ct-transformer-zh-en-vocab272727-2024-04-12/model.onnx";
+  punctuation_config.model.num_threads = 1;
+  punctuation_config.model.debug = false;
+  punctuation_config.model.provider = "cpu";
+
+  OfflinePunctuation punct = OfflinePunctuation::Create(punctuation_config);
+  if (!punct.Get()) {
+    std::cerr << "Failed to create punctuation model. Please check your config\n";
+    return -1;
+  }
+
+  std::string text = "你好吗how are you Fantasitic 谢谢我很好你怎么样呢";
+  std::string text_with_punct = punct.AddPunctuation(text);
+  std::cout << "Original text: " << text << std::endl;
+  std::cout << "With punctuation: " << text_with_punct << std::endl;
+
+  return 0;
+}

@@ -821,4 +821,33 @@ bool FileExists(const std::string &filename) {
   return SherpaOnnxFileExists(filename.c_str());
 }
 
+// ============================================================
+// For Offline Punctuation
+// ============================================================
+OfflinePunctuation OfflinePunctuation::Create(const OfflinePunctuationConfig &config) {
+  struct SherpaOnnxOfflinePunctuationConfig c;
+  memset(&c, 0, sizeof(c));
+  c.model.ct_transformer = config.model.ct_transformer.c_str();
+  c.model.num_threads = config.model.num_threads;
+  c.model.debug = config.model.debug;
+  c.model.provider = config.model.provider.c_str();
+
+  const SherpaOnnxOfflinePunctuation *punct = SherpaOnnxCreateOfflinePunctuation(&c);
+  return OfflinePunctuation(punct);
+}
+
+OfflinePunctuation::OfflinePunctuation(const SherpaOnnxOfflinePunctuation *p)
+  : MoveOnly<OfflinePunctuation, SherpaOnnxOfflinePunctuation>(p) {}
+
+void OfflinePunctuation::Destroy(const SherpaOnnxOfflinePunctuation *p) const {
+  SherpaOnnxDestroyOfflinePunctuation(p);
+}
+
+std::string OfflinePunctuation::AddPunctuation(const std::string &text) const {
+  const char *result = SherpaOfflinePunctuationAddPunct(p_, text.c_str());
+  std::string ans(result);
+  SherpaOfflinePunctuationFreeText(result);
+  return ans;
+}
+
 }  // namespace sherpa_onnx::cxx

@@ -673,6 +673,34 @@ SHERPA_ONNX_API std::string GetGitSha1();
 SHERPA_ONNX_API std::string GetGitDate();
 SHERPA_ONNX_API bool FileExists(const std::string &filename);
 
+// ============================================================================
+// Offline Punctuation
+// ============================================================================
+struct OfflinePunctuationModelConfig {
+  std::string ct_transformer;
+  int32_t num_threads = 1;
+  bool debug = false;
+  std::string provider = "cpu";
+};
+
+struct OfflinePunctuationConfig {
+  OfflinePunctuationModelConfig model;
+};
+
+class SHERPA_ONNX_API OfflinePunctuation
+    : public MoveOnly<OfflinePunctuation, SherpaOnnxOfflinePunctuation> {
+ public:
+  static OfflinePunctuation Create(const OfflinePunctuationConfig &config);
+
+  void Destroy(const SherpaOnnxOfflinePunctuation *p) const;
+
+  // Add punctuations to the input text and return it.
+  std::string AddPunctuation(const std::string &text) const;
+
+ private:
+  explicit OfflinePunctuation(const SherpaOnnxOfflinePunctuation *p);
+};
+
 }  // namespace sherpa_onnx::cxx
 
 #endif  // SHERPA_ONNX_C_API_CXX_API_H_