1 files changed, 149 insertions, 0 deletions
diff --git a/src/nix/command.hh b/src/nix/command.hh
new file mode 100644
index 000000000000..dc7b2637d66a
--- /dev/null
+++ b/src/nix/command.hh
@@ -0,0 +1,149 @@
+#pragma once
+
+#include "args.hh"
+
+namespace nix {
+
+struct Value;
+class EvalState;
+
+/* A command is an argument parser that can be executed by calling its
+   run() method. */
+struct Command : virtual Args
+{
+    virtual std::string name() = 0;
+    virtual void prepare() { };
+    virtual void run() = 0;
+
+    struct Example
+    {
+        std::string description;
+        std::string command;
+    };
+
+    typedef std::list<Example> Examples;
+
+    virtual Examples examples() { return Examples(); }
+
+    void printHelp(const string & programName, std::ostream & out) override;
+};
+
+class Store;
+
+/* A command that require a Nix store. */
+struct StoreCommand : virtual Command
+{
+    std::string storeUri;
+    StoreCommand();
+    void run() override;
+    ref<Store> getStore();
+    virtual ref<Store> createStore();
+    virtual void run(ref<Store>) = 0;
+
+private:
+    std::shared_ptr<Store> _store;
+};
+
+struct Installable
+{
+    virtual std::string what() = 0;
+
+    virtual PathSet toBuildable()
+    {
+        throw Error("argument ‘%s’ cannot be built", what());
+    }
+
+    virtual Value * toValue(EvalState & state)
+    {
+        throw Error("argument ‘%s’ cannot be evaluated", what());
+    }
+};
+
+/* A command that operates on a list of "installables", which can be
+   store paths, attribute paths, Nix expressions, etc. */
+struct InstallablesCommand : virtual Args, StoreCommand
+{
+    std::vector<std::shared_ptr<Installable>> installables;
+    Path file;
+
+    InstallablesCommand()
+    {
+        mkFlag('f', "file", "file", "evaluate FILE rather than the default", &file);
+        expectArgs("installables", &_installables);
+    }
+
+    /* Return a value representing the Nix expression from which we
+       are installing. This is either the file specified by ‘--file’,
+       or an attribute set constructed from $NIX_PATH, e.g. ‘{ nixpkgs
+       = import ...; bla = import ...; }’. */
+    Value * getSourceExpr(EvalState & state);
+
+    std::vector<std::shared_ptr<Installable>> parseInstallables(ref<Store> store, Strings installables);
+
+    PathSet buildInstallables(ref<Store> store, bool dryRun);
+
+    ref<EvalState> getEvalState();
+
+    void prepare() override;
+
+private:
+
+    Strings _installables;
+
+    std::shared_ptr<EvalState> evalState;
+
+    Value * vSourceExpr = 0;
+};
+
+/* A command that operates on zero or more store paths. */
+struct StorePathsCommand : public InstallablesCommand
+{
+private:
+
+    bool recursive = false;
+    bool all = false;
+
+public:
+
+    StorePathsCommand();
+
+    using StoreCommand::run;
+
+    virtual void run(ref<Store> store, Paths storePaths) = 0;
+
+    void run(ref<Store> store) override;
+};
+
+typedef std::map<std::string, ref<Command>> Commands;
+
+/* An argument parser that supports multiple subcommands,
+   i.e. ‘<command> <subcommand>’. */
+class MultiCommand : virtual Args
+{
+public:
+    Commands commands;
+
+    std::shared_ptr<Command> command;
+
+    MultiCommand(const Commands & commands);
+
+    void printHelp(const string & programName, std::ostream & out) override;
+
+    bool processFlag(Strings::iterator & pos, Strings::iterator end) override;
+
+    bool processArgs(const Strings & args, bool finish) override;
+};
+
+/* A helper class for registering commands globally. */
+struct RegisterCommand
+{
+    static Commands * commands;
+
+    RegisterCommand(ref<Command> command)
+    {
+        if (!commands) commands = new Commands;
+        commands->emplace(command->name(), command);
+    }
+};
+
+}