1 files changed, 81 insertions, 0 deletions
diff --git a/third_party/nix/src/nix/edit.cc b/third_party/nix/src/nix/edit.cc
new file mode 100644
index 0000000000..a6169f1183
--- /dev/null
+++ b/third_party/nix/src/nix/edit.cc
@@ -0,0 +1,81 @@
+#include "command.hh"
+#include "shared.hh"
+#include "eval.hh"
+#include "attr-path.hh"
+#include "progress-bar.hh"
+
+#include <unistd.h>
+
+using namespace nix;
+
+struct CmdEdit : InstallableCommand
+{
+    std::string name() override
+    {
+        return "edit";
+    }
+
+    std::string description() override
+    {
+        return "open the Nix expression of a Nix package in $EDITOR";
+    }
+
+    Examples examples() override
+    {
+        return {
+            Example{
+                "To open the Nix expression of the GNU Hello package:",
+                "nix edit nixpkgs.hello"
+            },
+        };
+    }
+
+    void run(ref<Store> store) override
+    {
+        auto state = getEvalState();
+
+        auto v = installable->toValue(*state);
+
+        Value * v2;
+        try {
+            auto dummyArgs = state->allocBindings(0);
+            v2 = findAlongAttrPath(*state, "meta.position", *dummyArgs, *v);
+        } catch (Error &) {
+            throw Error("package '%s' has no source location information", installable->what());
+        }
+
+        auto pos = state->forceString(*v2);
+        debug("position is %s", pos);
+
+        auto colon = pos.rfind(':');
+        if (colon == std::string::npos)
+            throw Error("cannot parse meta.position attribute '%s'", pos);
+
+        std::string filename(pos, 0, colon);
+        int lineno;
+        try {
+            lineno = std::stoi(std::string(pos, colon + 1));
+        } catch (std::invalid_argument & e) {
+            throw Error("cannot parse line number '%s'", pos);
+        }
+
+        auto editor = getEnv("EDITOR", "cat");
+
+        auto args = tokenizeString<Strings>(editor);
+
+        if (editor.find("emacs") != std::string::npos ||
+            editor.find("nano") != std::string::npos ||
+            editor.find("vim") != std::string::npos)
+            args.push_back(fmt("+%d", lineno));
+
+        args.push_back(filename);
+
+        stopProgressBar();
+
+        execvp(args.front().c_str(), stringsToCharPtrs(args).data());
+
+        throw SysError("cannot run editor '%s'", editor);
+    }
+};
+
+static RegisterCommand r1(make_ref<CmdEdit>());