1 files changed, 53 insertions, 0 deletions
diff --git a/src/nix/fmt.cc b/src/nix/fmt.cc
new file mode 100644
index 000000000..e5d44bd38
--- /dev/null
+++ b/src/nix/fmt.cc
@@ -0,0 +1,53 @@
+#include "command.hh"
+#include "run.hh"
+
+using namespace nix;
+
+struct CmdFmt : SourceExprCommand {
+    std::vector<std::string> args;
+
+    CmdFmt() { expectArgs({.label = "args", .handler = {&args}}); }
+
+    std::string description() override {
+        return "reformat your code in the standard style";
+    }
+
+    std::string doc() override {
+        return
+          #include "fmt.md"
+          ;
+    }
+
+    Category category() override { return catSecondary; }
+
+    Strings getDefaultFlakeAttrPaths() override {
+        return Strings{"formatter." + settings.thisSystem.get()};
+    }
+
+    Strings getDefaultFlakeAttrPathPrefixes() override { return Strings{}; }
+
+    void run(ref<Store> store) {
+        auto evalState = getEvalState();
+        auto evalStore = getEvalStore();
+
+        auto installable = parseInstallable(store, ".");
+        auto app = installable->toApp(*evalState).resolve(evalStore, store);
+
+        Strings programArgs{app.program};
+
+        // Propagate arguments from the CLI
+        if (args.empty()) {
+            // Format the current flake out of the box
+            programArgs.push_back(".");
+        } else {
+            // User wants more power, let them decide which paths to include/exclude
+            for (auto &i : args) {
+                programArgs.push_back(i);
+            }
+        }
+
+        runProgramInStore(store, app.program, programArgs);
+    };
+};
+
+static auto r2 = registerCommand<CmdFmt>("fmt");