kapi: rework text device interface

1 files changed, 29 insertions, 0 deletions

diff --git a/kapi/src/cio.cpp b/kapi/src/cio.cpp
new file mode 100644
index 0000000..aa26d49
--- /dev/null
+++ b/kapi/src/cio.cpp
@@ -0,0 +1,29 @@
+#include "kapi/cio.hpp"
+
+#include <optional>
+#include <utility>
+
+namespace teachos::cio
+{
+  auto constinit null_device = output_device{};
+
+  auto constinit active_device = &null_device;
+
+  auto set_output_device(output_device & device) -> std::optional<output_device *>
+  {
+    if (&device == active_device)
+    {
+      return {};
+    }
+    return std::exchange(active_device, &device);
+  }
+
+  auto print(std::string_view text) -> void { active_device->write(text); }
+
+  auto println(std::string_view text) -> void { active_device->writeln(text); }
+
+  auto print_error(std::string_view text) -> void { active_device->write_error(text); }
+
+  auto println_error(std::string_view text) -> void { active_device->writeln_error(text); }
+
+}  // namespace teachos::cio
\ No newline at end of file