move argument parsing to new file

src/eval-args.hh

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <string>
+#include <nix/flake/flake.hh>
+#include <nix/args/root.hh>
+#include <nix/common-eval-args.hh>
+
+class MyArgs : virtual public nix::MixEvalArgs,
+               virtual public nix::MixCommonArgs,
+               virtual nix::RootArgs {
+  public:
+    std::string releaseExpr;
+    nix::Path gcRootsDir;
+    bool flake = false;
+    bool fromArgs = false;
+    bool meta = false;
+    bool showTrace = false;
+    bool impure = false;
+    bool forceRecurse = false;
+    bool checkCacheStatus = false;
+    size_t nrWorkers = 1;
+    size_t maxMemorySize = 4096;
+
+    // usually in MixFlakeOptions
+    nix::flake::LockFlags lockFlags = {.updateLockFile = false,
+                                       .writeLockFile = false,
+                                       .useRegistries = false,
+                                       .allowUnlocked = false};
+    MyArgs();
+
+    void parseArgs(char** argv, int argc);
+};