Split out `CmdRepl` and `editorFor`

The REPL itself and the `nix repl` CLI are conceptually different
things, and thus deserve to be in different files.

7 files changed, 102 insertions, 123 deletions

diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index 517cdf617..ab51c229d 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -4,6 +4,7 @@
 #include "derivations.hh"
 #include "nixexpr.hh"
 #include "profiles.hh"
+#include "repl.hh"
 
 #include <nlohmann/json.hpp>
 
@@ -121,7 +122,7 @@ ref<EvalState> EvalCommand::getEvalState()
             ;
 
         if (startReplOnEvalErrors) {
-            evalState->debugRepl = &runRepl;
+            evalState->debugRepl = &AbstractNixRepl::runSimple;
         };
     }
     return ref<EvalState>(evalState);
@@ -218,20 +219,6 @@ void StorePathCommand::run(ref<Store> store, std::vector<StorePath> && storePath
     run(store, *storePaths.begin());
 }
 
-Strings editorFor(const Path & file, uint32_t line)
-{
-    auto editor = getEnv("EDITOR").value_or("cat");
-    auto args = tokenizeString<Strings>(editor);
-    if (line > 0 && (
-        editor.find("emacs") != std::string::npos ||
-        editor.find("nano") != std::string::npos ||
-        editor.find("vim") != std::string::npos ||
-        editor.find("kak") != std::string::npos))
-        args.push_back(fmt("+%d", line));
-    args.push_back(file);
-    return args;
-}
-
 MixProfile::MixProfile()
 {
     addFlag({
diff --git a/src/libcmd/command.hh b/src/libcmd/command.hh
index d16bdbc4b..1516daa00 100644
--- a/src/libcmd/command.hh
+++ b/src/libcmd/command.hh
@@ -231,10 +231,6 @@ static RegisterCommand registerCommand2(std::vector<std::string> && name)
     return RegisterCommand(std::move(name), [](){ return make_ref<T>(); });
 }
 
-/* Helper function to generate args that invoke $EDITOR on
-   filename:lineno. */
-Strings editorFor(const Path & file, uint32_t line);
-
 struct MixProfile : virtual StoreCommand
 {
     std::optional<Path> profile;
@@ -284,8 +280,4 @@ void printClosureDiff(
     const StorePath & afterPath,
     std::string_view indent);
 
-
-void runRepl(
-    ref<EvalState> evalState,
-    const ValMap & extraEnv);
 }
diff --git a/src/libcmd/editor-for.cc b/src/libcmd/editor-for.cc
new file mode 100644
index 000000000..f674f32bd
--- /dev/null
+++ b/src/libcmd/editor-for.cc
@@ -0,0 +1,20 @@
+#include "util.hh"
+#include "editor-for.hh"
+
+namespace nix {
+
+Strings editorFor(const Path & file, uint32_t line)
+{
+    auto editor = getEnv("EDITOR").value_or("cat");
+    auto args = tokenizeString<Strings>(editor);
+    if (line > 0 && (
+        editor.find("emacs") != std::string::npos ||
+        editor.find("nano") != std::string::npos ||
+        editor.find("vim") != std::string::npos ||
+        editor.find("kak") != std::string::npos))
+        args.push_back(fmt("+%d", line));
+    args.push_back(file);
+    return args;
+}
+
+}
diff --git a/src/libcmd/editor-for.hh b/src/libcmd/editor-for.hh
new file mode 100644
index 000000000..8fbd08792
--- /dev/null
+++ b/src/libcmd/editor-for.hh
@@ -0,0 +1,11 @@
+#pragma once
+
+#include "types.hh"
+
+namespace nix {
+
+/* Helper function to generate args that invoke $EDITOR on
+   filename:lineno. */
+Strings editorFor(const Path & file, uint32_t line);
+
+}
diff --git a/src/libcmd/local.mk b/src/libcmd/local.mk
index 152bc388d..541a7d2ba 100644
--- a/src/libcmd/local.mk
+++ b/src/libcmd/local.mk
@@ -6,7 +6,7 @@ libcmd_DIR := $(d)
 
 libcmd_SOURCES := $(wildcard $(d)/*.cc)
 
-libcmd_CXXFLAGS += -I src/libutil -I src/libstore -I src/libexpr -I src/libmain -I src/libfetchers -I src/nix
+libcmd_CXXFLAGS += -I src/libutil -I src/libstore -I src/libexpr -I src/libmain -I src/libfetchers
 
 libcmd_LDFLAGS = $(EDITLINE_LIBS) $(LOWDOWN_LIBS) -pthread
 
diff --git a/src/libcmd/repl.cc b/src/libcmd/repl.cc
index 4158439b6..7c7d13659 100644
--- a/src/libcmd/repl.cc
+++ b/src/libcmd/repl.cc
@@ -19,6 +19,8 @@ extern "C" {
 }
 #endif
 
+#include "repl.hh"
+
 #include "ansicolor.hh"
 #include "shared.hh"
 #include "eval.hh"
@@ -31,7 +33,9 @@ extern "C" {
 #include "get-drvs.hh"
 #include "derivations.hh"
 #include "globals.hh"
-#include "command.hh"
+#include "flake/flake.hh"
+#include "flake/lockfile.hh"
+#include "editor-for.hh"
 #include "finally.hh"
 #include "markdown.hh"
 #include "local-fs-store.hh"
@@ -45,18 +49,16 @@ extern "C" {
 namespace nix {
 
 struct NixRepl
+    : AbstractNixRepl,
     #if HAVE_BOEHMGC
-    : gc
+    gc
     #endif
 {
     std::string curDir;
-    ref<EvalState> state;
-    Bindings * autoArgs;
 
     size_t debugTraceIndex;
 
     Strings loadedFiles;
-    typedef std::vector<std::pair<Value*,std::string>> AnnotatedValues;
     std::function<AnnotatedValues()> getValues;
 
     const static int envSize = 32768;
@@ -69,8 +71,11 @@ struct NixRepl
 
     NixRepl(const Strings & searchPath, nix::ref<Store> store,ref<EvalState> state,
             std::function<AnnotatedValues()> getValues);
-    ~NixRepl();
-    void mainLoop();
+    virtual ~NixRepl();
+
+    void mainLoop() override;
+    void initEnv() override;
+
     StringSet completePrefix(const std::string & prefix);
     bool getLine(std::string & input, const std::string & prompt);
     StorePath getDerivationPath(Value & v);
@@ -78,7 +83,6 @@ struct NixRepl
 
     void loadFile(const Path & path);
     void loadFlake(const std::string & flakeRef);
-    void initEnv();
     void loadFiles();
     void reloadFiles();
     void addAttrsToScope(Value & attrs);
@@ -92,7 +96,6 @@ struct NixRepl
     std::ostream & printValue(std::ostream & str, Value & v, unsigned int maxDepth, ValuesSeen & seen);
 };
 
-
 std::string removeWhitespace(std::string s)
 {
     s = chomp(s);
@@ -104,7 +107,7 @@ std::string removeWhitespace(std::string s)
 
 NixRepl::NixRepl(const Strings & searchPath, nix::ref<Store> store, ref<EvalState> state,
             std::function<NixRepl::AnnotatedValues()> getValues)
-    : state(state)
+    : AbstractNixRepl(state)
     , debugTraceIndex(0)
     , getValues(getValues)
     , staticEnv(new StaticEnv(false, state->staticBaseEnv.get()))
@@ -1029,8 +1032,22 @@ std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int m
     return str;
 }
 
-void runRepl(
-    ref<EvalState>evalState,
+
+std::unique_ptr<AbstractNixRepl> AbstractNixRepl::create(
+   const Strings & searchPath, nix::ref<Store> store, ref<EvalState> state,
+   std::function<AnnotatedValues()> getValues)
+{
+    return std::make_unique<NixRepl>(
+        searchPath,
+        openStore(),
+        state,
+        getValues
+    );
+}
+
+
+void AbstractNixRepl::runSimple(
+    ref<EvalState> evalState,
     const ValMap & extraEnv)
 {
     auto getValues = [&]()->NixRepl::AnnotatedValues{
@@ -1054,91 +1071,4 @@ void runRepl(
     repl->mainLoop();
 }
 
-struct CmdRepl : InstallablesCommand
-{
-    CmdRepl() {
-        evalSettings.pureEval = false;
-    }
-
-    void prepare() override
-    {
-        if (!settings.isExperimentalFeatureEnabled(Xp::ReplFlake) && !(file) && this->_installables.size() >= 1) {
-            warn("future versions of Nix will require using `--file` to load a file");
-            if (this->_installables.size() > 1)
-                warn("more than one input file is not currently supported");
-            auto filePath = this->_installables[0].data();
-            file = std::optional(filePath);
-            _installables.front() = _installables.back();
-            _installables.pop_back();
-        }
-        installables = InstallablesCommand::load();
-    }
-
-    std::vector<std::string> files;
-
-    Strings getDefaultFlakeAttrPaths() override
-    {
-        return {""};
-    }
-
-    bool useDefaultInstallables() override
-    {
-        return file.has_value() or expr.has_value();
-    }
-
-    bool forceImpureByDefault() override
-    {
-        return true;
-    }
-
-    std::string description() override
-    {
-        return "start an interactive environment for evaluating Nix expressions";
-    }
-
-    std::string doc() override
-    {
-        return
-          #include "repl.md"
-          ;
-    }
-
-    void run(ref<Store> store) override
-    {
-        auto state = getEvalState();
-        auto getValues = [&]()->NixRepl::AnnotatedValues{
-            auto installables = load();
-            NixRepl::AnnotatedValues values;
-            for (auto & installable: installables){
-                auto what = installable->what();
-                if (file){
-                    auto [val, pos] = installable->toValue(*state);
-                    auto what = installable->what();
-                    state->forceValue(*val, pos);
-                    auto autoArgs = getAutoArgs(*state);
-                    auto valPost = state->allocValue();
-                    state->autoCallFunction(*autoArgs, *val, *valPost);
-                    state->forceValue(*valPost, pos);
-                    values.push_back( {valPost, what });
-                } else {
-                    auto [val, pos] = installable->toValue(*state);
-                    values.push_back( {val, what} );
-                }
-            }
-            return values;
-        };
-        auto repl = std::make_unique<NixRepl>(
-            searchPath,
-            openStore(),
-            state,
-            getValues
-        );
-        repl->autoArgs = getAutoArgs(*repl->state);
-        repl->initEnv();
-        repl->mainLoop();
-    }
-};
-
-static auto rCmdRepl = registerCommand<CmdRepl>("repl");
-
 }
diff --git a/src/libcmd/repl.hh b/src/libcmd/repl.hh
new file mode 100644
index 000000000..dfccc93e7
--- /dev/null
+++ b/src/libcmd/repl.hh
@@ -0,0 +1,39 @@
+#pragma once
+
+#include "eval.hh"
+
+#if HAVE_BOEHMGC
+#define GC_INCLUDE_NEW
+#include <gc/gc_cpp.h>
+#endif
+
+namespace nix {
+
+struct AbstractNixRepl
+{
+    ref<EvalState> state;
+    Bindings * autoArgs;
+
+    AbstractNixRepl(ref<EvalState> state)
+        : state(state)
+    { }
+
+    virtual ~AbstractNixRepl()
+    { }
+
+    typedef std::vector<std::pair<Value*,std::string>> AnnotatedValues;
+
+    static std::unique_ptr<AbstractNixRepl> create(
+        const Strings & searchPath, nix::ref<Store> store, ref<EvalState> state,
+        std::function<AnnotatedValues()> getValues);
+
+    static void runSimple(
+        ref<EvalState> evalState,
+        const ValMap & extraEnv);
+
+    virtual void initEnv() = 0;
+
+    virtual void mainLoop() = 0;
+};
+
+}