Add CreateOnlineStreamWithHotwords to C API (#323)

* add default visibility to SHERPA_ONNX_EXPORT

* expose CreateOnlineStreamWithHotwords method via C API

Co-authored-by: Nick Fisher <nick.fisher@polyvox.app>

@@ -107,6 +107,13 @@ SherpaOnnxOnlineStream *CreateOnlineStream(
   return stream;
 }
 
+SherpaOnnxOnlineStream *CreateOnlineStreamWithHotwords(
+    const SherpaOnnxOnlineRecognizer *recognizer, const char *hotwords) {
+  SherpaOnnxOnlineStream *stream =
+      new SherpaOnnxOnlineStream(recognizer->impl->CreateStream(hotwords));
+  return stream;
+}
+
 void DestroyOnlineStream(SherpaOnnxOnlineStream *stream) { delete stream; }
 
 void AcceptWaveform(SherpaOnnxOnlineStream *stream, int32_t sample_rate,

@@ -31,7 +31,7 @@ extern "C" {
 #define SHERPA_ONNX_IMPORT
 #endif
 #else  // WIN32
-#define SHERPA_ONNX_EXPORT
+#define SHERPA_ONNX_EXPORT __attribute__((visibility("default"))) 
 #define SHERPA_ONNX_IMPORT SHERPA_ONNX_EXPORT
 #endif
 
@@ -178,6 +178,13 @@ SHERPA_ONNX_API void DestroyOnlineRecognizer(
 SHERPA_ONNX_API SherpaOnnxOnlineStream *CreateOnlineStream(
     const SherpaOnnxOnlineRecognizer *recognizer);
 
+/// Create an online stream for accepting wave samples with the specified hot words.
+///
+/// @param recognizer  A pointer returned by CreateOnlineRecognizer()
+/// @return Return a pointer to an OnlineStream. The user has to invoke
+///         DestroyOnlineStream() to free it to avoid memory leak.
+SHERPA_ONNX_API SherpaOnnxOnlineStream *CreateOnlineStreamWithHotwords(const SherpaOnnxOnlineRecognizer *recognizer, const char *hotwords);
+
 /// Destroy an online stream.
 ///
 /// @param stream A pointer returned by CreateOnlineStream()