1 files changed, 65 insertions, 3 deletions

diff --git a/src/libcmd/installables.hh b/src/libcmd/installables.hh
index ced6b3f10..f4bf0d406 100644
--- a/src/libcmd/installables.hh
+++ b/src/libcmd/installables.hh
@@ -5,6 +5,7 @@
 #include "path-with-outputs.hh"
 #include "derived-path.hh"
 #include "eval.hh"
+#include "store-api.hh"
 #include "flake/flake.hh"
 
 #include <optional>
@@ -29,6 +30,27 @@ struct UnresolvedApp
     App resolve(ref<Store> evalStore, ref<Store> store);
 };
 
+enum class Realise {
+    /* Build the derivation. Postcondition: the
+       derivation outputs exist. */
+    Outputs,
+    /* Don't build the derivation. Postcondition: the store derivation
+       exists. */
+    Derivation,
+    /* Evaluate in dry-run mode. Postcondition: nothing. */
+    // FIXME: currently unused, but could be revived if we can
+    // evaluate derivations in-memory.
+    Nothing
+};
+
+/* How to handle derivations in commands that operate on store paths. */
+enum class OperateOn {
+    /* Operate on the output path. */
+    Output,
+    /* Operate on the .drv path. */
+    Derivation
+};
+
 struct Installable
 {
     virtual ~Installable() { }
@@ -68,6 +90,46 @@ struct Installable
     {
         return FlakeRef::fromAttrs({{"type","indirect"}, {"id", "nixpkgs"}});
     }
+
+    static BuiltPaths build(
+        ref<Store> evalStore,
+        ref<Store> store,
+        Realise mode,
+        const std::vector<std::shared_ptr<Installable>> & installables,
+        BuildMode bMode = bmNormal);
+
+    static std::vector<std::pair<std::shared_ptr<Installable>, BuiltPath>> build2(
+        ref<Store> evalStore,
+        ref<Store> store,
+        Realise mode,
+        const std::vector<std::shared_ptr<Installable>> & installables,
+        BuildMode bMode = bmNormal);
+
+    static std::set<StorePath> toStorePaths(
+        ref<Store> evalStore,
+        ref<Store> store,
+        Realise mode,
+        OperateOn operateOn,
+        const std::vector<std::shared_ptr<Installable>> & installables);
+
+    static StorePath toStorePath(
+        ref<Store> evalStore,
+        ref<Store> store,
+        Realise mode,
+        OperateOn operateOn,
+        std::shared_ptr<Installable> installable);
+
+    static std::set<StorePath> toDerivations(
+        ref<Store> store,
+        const std::vector<std::shared_ptr<Installable>> & installables,
+        bool useDeriver = false);
+
+    static BuiltPaths toBuiltPaths(
+        ref<Store> evalStore,
+        ref<Store> store,
+        Realise mode,
+        OperateOn operateOn,
+        const std::vector<std::shared_ptr<Installable>> & installables);
 };
 
 struct InstallableValue : Installable
@@ -79,7 +141,6 @@ struct InstallableValue : Installable
     struct DerivationInfo
     {
         StorePath drvPath;
-        std::optional<StorePath> outPath;
         std::string outputName;
     };
 
@@ -102,8 +163,9 @@ struct InstallableFlake : InstallableValue
         SourceExprCommand * cmd,
         ref<EvalState> state,
         FlakeRef && flakeRef,
-        Strings && attrPaths,
-        Strings && prefixes,
+        std::string_view fragment,
+        Strings attrPaths,
+        Strings prefixes,
         const flake::LockFlags & lockFlags);
 
     std::string what() const override { return flakeRef.to_string() + "#" + *attrPaths.begin(); }