Merge pull request #103 from zhaofengli/cli-expr

Add support for passing a Nix expression on the command line

src/nix-eval-jobs.cc

@@ -30,8 +30,6 @@
 using namespace nix;
 using namespace nlohmann;
 
-typedef enum { evalAuto, evalImpure, evalPure } pureEval;
-
 // Safe to ignore - the args will be static.
 #ifdef __GNUC__
 #pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
@@ -39,14 +37,15 @@ typedef enum { evalAuto, evalImpure, evalPure } pureEval;
 #pragma clang diagnostic ignored "-Wnon-virtual-dtor"
 #endif
 struct MyArgs : MixEvalArgs, MixCommonArgs {
-    Path releaseExpr;
+    std::string releaseExpr;
     Path gcRootsDir;
     bool flake = false;
+    bool fromArgs = false;
     bool meta = false;
     bool showTrace = false;
+    bool impure = false;
     size_t nrWorkers = 1;
     size_t maxMemorySize = 4096;
-    pureEval evalMode = evalAuto;
 
     MyArgs() : MixCommonArgs("nix-eval-jobs") {
         addFlag({
@@ -65,11 +64,9 @@ struct MyArgs : MixEvalArgs, MixCommonArgs {
             }},
         });
 
-        addFlag({
-            .longName = "impure",
-            .description = "set evaluation mode",
-            .handler = {[&]() { evalMode = evalImpure; }},
-        });
+        addFlag({.longName = "impure",
+                 .description = "allow impure expressions",
+                 .handler = {&impure, true}});
 
         addFlag({.longName = "gc-roots-dir",
                  .description = "garbage collector roots directory",
@@ -101,6 +98,11 @@ struct MyArgs : MixEvalArgs, MixCommonArgs {
                      "print out a stack trace in case of evaluation errors",
                  .handler = {&showTrace, true}});
 
+        addFlag({.longName = "expr",
+                 .shortName = 'E',
+                 .description = "treat the argument as a Nix expression",
+                 .handler = {&fromArgs, true}});
+
         expectArg("expr", &releaseExpr);
     }
 };
@@ -115,7 +117,12 @@ static MyArgs myArgs;
 static Value *releaseExprTopLevelValue(EvalState &state, Bindings &autoArgs) {
     Value vTop;
 
-    state.evalFile(lookupFileArg(state, myArgs.releaseExpr), vTop);
+    if (myArgs.fromArgs) {
+        Expr *e = state.parseExprFromString(myArgs.releaseExpr, absPath("."));
+        state.eval(e, vTop);
+    } else {
+        state.evalFile(lookupFileArg(state, myArgs.releaseExpr), vTop);
+    }
 
     auto vRoot = state.allocValue();
 
@@ -493,9 +500,11 @@ int main(int argc, char **argv) {
 
         /* When building a flake, use pure evaluation (no access to
            'getEnv', 'currentSystem' etc. */
-        evalSettings.pureEval = myArgs.evalMode == evalAuto
-                                    ? myArgs.flake
-                                    : myArgs.evalMode == evalPure;
+        if (myArgs.impure) {
+            evalSettings.pureEval = false;
+        } else if (myArgs.flake) {
+            evalSettings.pureEval = true;
+        }
 
         if (myArgs.releaseExpr == "")
             throw UsageError("no expression specified");

tests/test_eval.py

@@ -55,3 +55,6 @@ def test_flake() -> None:
 
 def test_expression() -> None:
     common_test(["ci.nix"])
+
+    with open(TEST_ROOT.joinpath("assets/ci.nix"), "r") as ci_nix:
+        common_test(["-E", ci_nix.read()])