Support CoreML for macOS (#151)

sherpa-onnx/csrc/provider.h

@@ -0,0 +1,31 @@
+// sherpa-onnx/csrc/provider.h
+//
+// Copyright (c)  2023  Xiaomi Corporation
+
+#ifndef SHERPA_ONNX_CSRC_PROVIDER_H_
+#define SHERPA_ONNX_CSRC_PROVIDER_H_
+
+#include <string>
+
+namespace sherpa_onnx {
+
+// Please refer to
+// https://github.com/microsoft/onnxruntime/blob/main/java/src/main/java/ai/onnxruntime/OrtProvider.java
+// for a list of available providers
+enum class Provider {
+  kCPU = 0,     // CPUExecutionProvider
+  kCUDA = 1,    // CUDAExecutionProvider
+  kCoreML = 2,  // CoreMLExecutionProvider
+};
+
+/**
+ * Convert a string to an enum.
+ *
+ * @param s We will convert it to lowercase before comparing.
+ * @return Return an instance of Provider.
+ */
+Provider StringToProvider(std::string s);
+
+}  // namespace sherpa_onnx
+
+#endif  // SHERPA_ONNX_CSRC_PROVIDER_H_