lix/src/nix/edit.cc

#include "command.hh"
#include "shared.hh"
#include "eval.hh"
#include "attr-path.hh"

#include <unistd.h>

using namespace nix;

struct CmdEdit : InstallablesCommand
{
    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();

        for (auto & i : installables) {
            auto v = i->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", i->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 = std::stoi(std::string(pos, colon + 1));

            auto editor = getEnv("EDITOR", "cat");

            Strings args{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);

            execvp(editor.c_str(), stringsToCharPtrs(args).data());

            throw SysError("cannot run editor '%s'", editor);
        }
    }
};

static RegisterCommand r1(make_ref<CmdEdit>());