nix-expr: Add primops to EvalSettings

src/libexpr/eval-settings.cc

@@ -103,4 +103,13 @@ Path getNixDefExpr()
         : getHome() + "/.nix-defexpr";
 }
 
+void EvalSettings::addPrimOp(PrimOp && primOp)
+{
+    extraPrimOps.emplace_back(std::move(primOp));
 }
+void EvalSettings::addPrimOp(const PrimOp & primOp)
+{
+    extraPrimOps.emplace_back(PrimOp(primOp));
+}
+
+} // namespace nix

src/libexpr/eval-settings.hh

@@ -7,6 +7,7 @@
 namespace nix {
 
 class EvalState;
+struct PrimOp;
 
 struct EvalSettings : Config
 {
@@ -50,6 +51,17 @@ struct EvalSettings : Config
 
     LookupPathHooks lookupPathHooks;
 
+    std::vector<PrimOp> extraPrimOps;
+
+    /**
+     * Register a primop to be added when an EvalState is created from these settings.
+     */
+    void addPrimOp(PrimOp && primOp);
+    /**
+     * Register a primop to be added when an EvalState is created from these settings.
+     */
+    void addPrimOp(const PrimOp & primOp);
+
     Setting<bool> enableNativeCode{this, false, "allow-unsafe-native-code-during-evaluation", R"(
         Enable built-in functions that allow executing native code.
 

src/libexpr/eval.cc

@@ -353,7 +353,7 @@ EvalState::EvalState(
         #include "fetchurl.nix.gen.hh"
     );
 
-    createBaseEnv();
+    createBaseEnv(settings);
 }
 
 

src/libexpr/eval.hh

@@ -633,7 +633,7 @@ private:
 
     unsigned int baseEnvDispl = 0;
 
-    void createBaseEnv();
+    void createBaseEnv(const EvalSettings & settings);
 
     Value * addConstant(const std::string & name, Value & v, Constant info);
 

src/libexpr/primops.cc

@@ -4669,7 +4669,7 @@ RegisterPrimOp::RegisterPrimOp(PrimOp && primOp)
 }
 
 
-void EvalState::createBaseEnv()
+void EvalState::createBaseEnv(const EvalSettings & evalSettings)
 {
     baseEnv.up = 0;
 
@@ -4928,6 +4928,12 @@ void EvalState::createBaseEnv()
                 addPrimOp(std::move(primOpAdjusted));
             }
 
+    for (auto & primOp : evalSettings.extraPrimOps) {
+        auto primOpAdjusted = primOp;
+        primOpAdjusted.arity = std::max(primOp.args.size(), primOp.arity);
+        addPrimOp(std::move(primOpAdjusted));
+    }
+
     /* Add a wrapper around the derivation primop that computes the
        `drvPath' and `outPath' attributes lazily.