add streaming websocket server and client (#62)

sherpa-onnx/csrc/file-utils.cc

@@ -0,0 +1,24 @@
+// sherpa-onnx/csrc/file-utils.cc
+//
+// Copyright (c)  2022-2023  Xiaomi Corporation
+
+#include "sherpa-onnx/csrc/file-utils.h"
+
+#include <fstream>
+#include <string>
+
+#include "sherpa-onnx/csrc/log.h"
+
+namespace sherpa_onnx {
+
+bool FileExists(const std::string &filename) {
+  return std::ifstream(filename).good();
+}
+
+void AssertFileExists(const std::string &filename) {
+  if (!FileExists(filename)) {
+    SHERPA_ONNX_LOG(FATAL) << filename << " does not exist!";
+  }
+}
+
+}  // namespace sherpa_onnx