1 files changed, 48 insertions, 0 deletions
diff --git a/src/libcmd/repl-interacter.hh b/src/libcmd/repl-interacter.hh
new file mode 100644
index 000000000..e549bab36
--- /dev/null
+++ b/src/libcmd/repl-interacter.hh
@@ -0,0 +1,48 @@
+#pragma once
+/// @file
+
+#include "finally.hh"
+#include "types.hh"
+#include <functional>
+#include <string>
+
+namespace nix {
+
+namespace detail {
+/** Provides the completion hooks for the repl, without exposing its complete
+ * internals. */
+struct ReplCompleterMixin {
+    virtual StringSet completePrefix(const std::string & prefix) = 0;
+};
+};
+
+enum class ReplPromptType {
+    ReplPrompt,
+    ContinuationPrompt,
+};
+
+class ReplInteracter
+{
+public:
+    using Guard = Finally<std::function<void()>>;
+
+    virtual Guard init(detail::ReplCompleterMixin * repl) = 0;
+    /** Returns a boolean of whether the interacter got EOF */
+    virtual bool getLine(std::string & input, const std::string & prompt) = 0;
+    virtual ~ReplInteracter(){};
+};
+
+class ReadlineLikeInteracter : public virtual ReplInteracter
+{
+    std::string historyFile;
+public:
+    ReadlineLikeInteracter(std::string historyFile)
+        : historyFile(historyFile)
+    {
+    }
+    virtual Guard init(detail::ReplCompleterMixin * repl) override;
+    virtual bool getLine(std::string & input, const std::string & prompt) override;
+    virtual ~ReadlineLikeInteracter() override;
+};
+
+};