return timestamps for WebAssembly (#737)

sherpa-onnx/c-api/c-api.cc

@@ -243,6 +243,20 @@ void DestroyOnlineRecognizerResult(const SherpaOnnxOnlineRecognizerResult *r) {
   }
 }
 
+const char *GetOnlineStreamResultAsJson(
+    const SherpaOnnxOnlineRecognizer *recognizer,
+    const SherpaOnnxOnlineStream *stream) {
+  sherpa_onnx::OnlineRecognizerResult result =
+      recognizer->impl->GetResult(stream->impl.get());
+  std::string json = result.AsJsonString();
+  char *pJson = new char[json.size() + 1];
+  std::copy(json.begin(), json.end(), pJson);
+  pJson[json.size()] = 0;
+  return pJson;
+}
+
+void DestroyOnlineStreamResultJson(const char *s) { delete[] s; }
+
 void Reset(const SherpaOnnxOnlineRecognizer *recognizer,
            const SherpaOnnxOnlineStream *stream) {
   recognizer->impl->Reset(stream->impl.get());
@@ -409,7 +423,7 @@ void DecodeMultipleOfflineStreams(SherpaOnnxOfflineRecognizer *recognizer,
 }
 
 const SherpaOnnxOfflineRecognizerResult *GetOfflineStreamResult(
-    SherpaOnnxOfflineStream *stream) {
+    const SherpaOnnxOfflineStream *stream) {
   const sherpa_onnx::OfflineRecognitionResult &result =
       stream->impl->GetResult();
   const auto &text = result.text;
@@ -444,6 +458,19 @@ void DestroyOfflineRecognizerResult(
   }
 }
 
+const char *GetOfflineStreamResultAsJson(
+    const SherpaOnnxOfflineStream *stream) {
+  const sherpa_onnx::OfflineRecognitionResult &result =
+      stream->impl->GetResult();
+  std::string json = result.AsJsonString();
+  char *pJson = new char[json.size() + 1];
+  std::copy(json.begin(), json.end(), pJson);
+  pJson[json.size()] = 0;
+  return pJson;
+}
+
+void DestroyOfflineStreamResultJson(const char *s) { delete[] s; }
+
 // ============================================================
 // For Keyword Spot
 // ============================================================

sherpa-onnx/c-api/c-api.h

@@ -286,6 +286,16 @@ SHERPA_ONNX_API const SherpaOnnxOnlineRecognizerResult *GetOnlineStreamResult(
 SHERPA_ONNX_API void DestroyOnlineRecognizerResult(
     const SherpaOnnxOnlineRecognizerResult *r);
 
+/// Return the result as a json string.
+/// The user has to invoke
+/// DestroyOnlineStreamResultJson()
+/// to free the returned pointer to avoid memory leak
+SHERPA_ONNX_API const char *GetOnlineStreamResultAsJson(
+    const SherpaOnnxOnlineRecognizer *recognizer,
+    const SherpaOnnxOnlineStream *stream);
+
+SHERPA_ONNX_API void DestroyOnlineStreamResultJson(const char *s);
+
 /// Reset an OnlineStream , which clears the neural network model state
 /// and the state for decoding.
 ///
@@ -482,7 +492,7 @@ SHERPA_ONNX_API typedef struct SherpaOnnxOfflineRecognizerResult {
 ///         DestroyOnlineRecognizerResult() to free the returned pointer to
 ///         avoid memory leak.
 SHERPA_ONNX_API const SherpaOnnxOfflineRecognizerResult *GetOfflineStreamResult(
-    SherpaOnnxOfflineStream *stream);
+    const SherpaOnnxOfflineStream *stream);
 
 /// Destroy the pointer returned by GetOfflineStreamResult().
 ///
@@ -490,6 +500,14 @@ SHERPA_ONNX_API const SherpaOnnxOfflineRecognizerResult *GetOfflineStreamResult(
 SHERPA_ONNX_API void DestroyOfflineRecognizerResult(
     const SherpaOnnxOfflineRecognizerResult *r);
 
+/// Return the result as a json string.
+/// The user has to use DestroyOfflineStreamResultJson()
+/// to free the returned pointer to avoid memory leak
+SHERPA_ONNX_API const char *GetOfflineStreamResultAsJson(
+    const SherpaOnnxOfflineStream *stream);
+
+SHERPA_ONNX_API void DestroyOfflineStreamResultJson(const char *s);
+
 // ============================================================
 // For Keyword Spot
 // ============================================================