Added nonFlakeRequires and the command `nix flake deps`

4 files changed, 200 insertions, 93 deletions

diff --git a/src/libexpr/primops/flake.cc b/src/libexpr/primops/flake.cc
index 7cfb2038c..c4ae29022 100644
--- a/src/libexpr/primops/flake.cc
+++ b/src/libexpr/primops/flake.cc
@@ -18,20 +18,19 @@ std::shared_ptr<FlakeRegistry> readRegistry(const Path & path)
 {
     auto registry = std::make_shared<FlakeRegistry>();
 
-    try {
-        auto json = nlohmann::json::parse(readFile(path));
+    if (!pathExists(path))
+        return std::make_shared<FlakeRegistry>();
 
-        auto version = json.value("version", 0);
-        if (version != 1)
-            throw Error("flake registry '%s' has unsupported version %d", path, version);
+    auto json = nlohmann::json::parse(readFile(path));
 
-        auto flakes = json["flakes"];
-        for (auto i = flakes.begin(); i != flakes.end(); ++i) {
-            FlakeRegistry::Entry entry{FlakeRef(i->value("uri", ""))};
-            registry->entries.emplace(i.key(), entry);
-        }
-    } catch (SysError & e) {
-        if (e.errNo != ENOENT) throw;
+    auto version = json.value("version", 0);
+    if (version != 1)
+        throw Error("flake registry '%s' has unsupported version %d", path, version);
+
+    auto flakes = json["flakes"];
+    for (auto i = flakes.begin(); i != flakes.end(); ++i) {
+        FlakeRegistry::Entry entry{FlakeRef(i->value("uri", ""))};
+        registry->entries.emplace(i.key(), entry);
     }
 
     return registry;
@@ -54,7 +53,6 @@ Path getUserRegistryPath()
 {
     return getHome() + "/.config/nix/registry.json";
 }
-
 std::shared_ptr<FlakeRegistry> getGlobalRegistry()
 {
     // FIXME: get from nixos.org.
@@ -76,12 +74,20 @@ std::shared_ptr<FlakeRegistry> getFlagRegistry()
 const std::vector<std::shared_ptr<FlakeRegistry>> EvalState::getFlakeRegistries()
 {
     std::vector<std::shared_ptr<FlakeRegistry>> registries;
-    registries.push_back(getGlobalRegistry());
-    registries.push_back(getUserRegistry());
+    if (evalSettings.pureEval) {
+        registries.push_back(std::make_shared<FlakeRegistry>()); // global
+        registries.push_back(std::make_shared<FlakeRegistry>()); // user
+        registries.push_back(std::make_shared<FlakeRegistry>()); // local
+    } else {
+        registries.push_back(getGlobalRegistry());
+        registries.push_back(getUserRegistry());
+        registries.push_back(getLocalRegistry());
+    }
     registries.push_back(getFlagRegistry());
     return registries;
 }
 
+// Creates a Nix attribute set value listing all dependencies, so they can be used in `provides`.
 Value * makeFlakeRegistryValue(EvalState & state)
 {
     auto v = state.allocValue();
@@ -199,7 +205,7 @@ static FlakeSourceInfo fetchFlake(EvalState & state, const FlakeRef & flakeRef)
 
 Flake getFlake(EvalState & state, const FlakeRef & flakeRef)
 {
-    auto sourceInfo = fetchFlake(state, flakeRef);
+    FlakeSourceInfo sourceInfo = fetchFlake(state, flakeRef);
     debug("got flake source '%s' with revision %s",
         sourceInfo.storePath, sourceInfo.rev.value_or(Hash(htSHA1)).to_string(Base16, false));
 
@@ -209,18 +215,16 @@ Flake getFlake(EvalState & state, const FlakeRef & flakeRef)
     if (state.allowedPaths)
         state.allowedPaths->insert(flakePath);
 
-    FlakeRef newFlakeRef(flakeRef);
-    if (std::get_if<FlakeRef::IsGitHub>(&newFlakeRef.data)) {
-        FlakeSourceInfo srcInfo = fetchFlake(state, newFlakeRef);
-        if (srcInfo.rev) {
-            std::string uri = flakeRef.baseRef().to_string();
-            newFlakeRef = FlakeRef(uri + "/" + srcInfo.rev->to_string(Base16, false));
-        }
+    Flake flake(flakeRef);
+    if (std::get_if<FlakeRef::IsGitHub>(&flakeRef.data)) {
+        if (sourceInfo.rev)
+            flake.ref = FlakeRef(flakeRef.baseRef().to_string()
+                + "/" + sourceInfo.rev->to_string(Base16, false));
     }
 
-    Flake flake(newFlakeRef);
     flake.path = flakePath;
     flake.revCount = sourceInfo.revCount;
+    flake.path = flakePath;
 
     Value vInfo;
     state.evalFile(flakePath + "/flake.nix", vInfo); // FIXME: symlink attack
@@ -242,6 +246,15 @@ Flake getFlake(EvalState & state, const FlakeRef & flakeRef)
                 *(**requires).value->listElems()[n], *(**requires).pos)));
     }
 
+    if (std::optional<Attr *> nonFlakeRequires = vInfo.attrs->get(state.symbols.create("nonFlakeRequires"))) {
+        state.forceAttrs(*(**nonFlakeRequires).value, *(**nonFlakeRequires).pos);
+        for (Attr attr : *(*(**nonFlakeRequires).value).attrs) {
+            std::string myNonFlakeUri = state.forceStringNoCtx(*attr.value, *attr.pos);
+            FlakeRef nonFlakeRef = FlakeRef(myNonFlakeUri);
+            flake.nonFlakeRequires.insert_or_assign(attr.name, nonFlakeRef);
+        }
+    }
+
     if (auto provides = vInfo.attrs->get(state.symbols.create("provides"))) {
         state.forceFunction(*(**provides).value, *(**provides).pos);
         flake.vProvides = (**provides).value;
@@ -250,86 +263,107 @@ Flake getFlake(EvalState & state, const FlakeRef & flakeRef)
 
     auto lockFile = flakePath + "/flake.lock"; // FIXME: symlink attack
 
-    if (pathExists(lockFile)) {
-        flake.lockFile = readRegistry(lockFile);
-        for (auto & entry : flake.lockFile->entries)
-            if (!entry.second.ref.isImmutable())
-                throw Error("flake lock file '%s' contains mutable entry '%s'",
-                    lockFile, entry.second.ref.to_string());
-    }
+    flake.lockFile = readRegistry(lockFile);
+    for (auto & entry : flake.lockFile->entries)
+        if (!entry.second.ref.isImmutable())
+            throw Error("flake lock file '%s' contains mutable entry '%s'",
+                lockFile, entry.second.ref.to_string());
+
 
     return flake;
 }
 
+// Get the `NonFlake` corresponding to a `FlakeRef`.
+NonFlake getNonFlake(EvalState & state, const FlakeRef & flakeRef, FlakeId flakeId)
+{
+    FlakeSourceInfo sourceInfo = fetchFlake(state, flakeRef);
+    debug("got non-flake source '%s' with revision %s",
+        sourceInfo.storePath, sourceInfo.rev.value_or(Hash(htSHA1)).to_string(Base16, false));
+
+    auto flakePath = sourceInfo.storePath;
+    state.store->assertStorePath(flakePath);
+
+    if (state.allowedPaths)
+        state.allowedPaths->insert(flakePath);
+
+    NonFlake nonFlake(flakeRef);
+    if (std::get_if<FlakeRef::IsGitHub>(&flakeRef.data)) {
+        if (sourceInfo.rev)
+            nonFlake.ref = FlakeRef(flakeRef.baseRef().to_string()
+                + "/" + sourceInfo.rev->to_string(Base16, false));
+    }
+
+    nonFlake.path = flakePath;
+
+    nonFlake.id = flakeId;
+
+    return nonFlake;
+}
+
 /* Given a flake reference, recursively fetch it and its
    dependencies.
    FIXME: this should return a graph of flakes.
 */
-static std::tuple<FlakeId, std::map<FlakeId, Flake>> resolveFlake(EvalState & state,
-    const FlakeRef & topRef, bool impureTopRef)
+Dependencies resolveFlake(EvalState & state, const FlakeRef & topRef, bool impureTopRef)
 {
-    std::map<FlakeId, Flake> done;
-    std::queue<std::tuple<FlakeRef, bool>> todo;
-    std::optional<FlakeId> topFlakeId; /// FIXME: ambiguous
-    todo.push({topRef, true});
+    Dependencies deps;
+    std::queue<FlakeRef> todo;
+    bool isTopLevel = true;
+    todo.push(topRef);
 
     auto registries = state.getFlakeRegistries();
-    //std::shared_ptr<FlakeRegistry> localRegistry = registries.at(2);
 
     while (!todo.empty()) {
-        auto [flakeRef, toplevel] = todo.front();
+        auto flakeRef = todo.front();
         todo.pop();
 
         if (auto refData = std::get_if<FlakeRef::IsFlakeId>(&flakeRef.data)) {
             if (done.count(refData->id)) continue; // optimization
-            flakeRef = lookupFlake(state, flakeRef,
-                !evalSettings.pureEval || (toplevel && impureTopRef) ? registries : std::vector<std::shared_ptr<FlakeRegistry>>());
-            // This is why we need the `registries`.
-        }
-
-#if 0
-        if (evalSettings.pureEval && !flakeRef.isImmutable() && (!toplevel || !impureTopRef))
+            flakeRef = lookupFlake(state, flakeRef, registries);
+        if (evalSettings.pureEval && !flakeRef.isImmutable() && (!isTopLevel || !impureTopRef))
             throw Error("mutable flake '%s' is not allowed in pure mode; use --impure to disable", flakeRef.to_string());
-#endif
 
         auto flake = getFlake(state, flakeRef);
 
-        if (done.count(flake.id)) continue;
-
-        if (toplevel) topFlakeId = flake.id;
+        if (isTopLevel) {
+            deps.topFlakeId = flake.id;
+            isTopLevel = false;
+        }
 
-        for (auto & require : flake.requires)
-            todo.push({require, false});
+        for (auto & flakeRef : flake.requires)
+            todo.push(flakeRef);
 
-#if 0
-        // The following piece of code basically adds the FlakeRefs from
-        // the lockfiles of dependencies to the localRegistry. This is used
-        // to resolve future `FlakeId`s, in `lookupFlake` a bit above this.
-        if (flake.lockFile)
-            for (auto & entry : flake.lockFile->entries) {
-                if (localRegistry->entries.count(entry.first)) continue;
-                localRegistry->entries.emplace(entry.first, entry.second);
-            }
-#endif
+        for (auto & x : flake.nonFlakeRequires)
+            deps.nonFlakes.push_back(getNonFlake(state, x.second, x.first));
+            // TODO (Nick): If there are 2 non-flake dependencies with the same
+            // FlakeId, this will lead to trouble! One of the dependencies won't
+            // be used!
 
-        done.emplace(flake.id, std::move(flake));
+        deps.flakes.push_back(flake);
     }
 
-    assert(topFlakeId);
-    return {*topFlakeId, std::move(done)};
+    return deps;
 }
 
 FlakeRegistry updateLockFile(EvalState & evalState, FlakeRef & flakeRef)
 {
     FlakeRegistry newLockFile;
-    std::map<FlakeId, Flake> myDependencyMap = get<1>(resolveFlake(evalState, flakeRef, false));
+    Dependencies deps = resolveFlake(evalState, flakeRef, false);
     // Nick assumed that "topRefPure" means that the Flake for flakeRef can be
     // fetched purely.
-    for (auto const& require : myDependencyMap) {
-        FlakeRegistry::Entry entry = FlakeRegistry::Entry(require.second.ref);
-        // The FlakeRefs are immutable because they come out of the Flake objects,
-        // not from the requires.
-        newLockFile.entries.insert(std::pair<FlakeId, FlakeRegistry::Entry>(require.first, entry));
+    for (auto const& require : deps.flakes) {
+        FlakeRegistry::Entry entry = FlakeRegistry::Entry(require.ref);
+        // The FlakeRefs are immutable because they come out of the Flake objects.
+        if (require.id != deps.topFlakeId)
+            newLockFile.entries.insert_or_assign(require.id, entry);
+        // TODO (Nick): If there are 2 flake dependencies with the same FlakeId,
+        // one of them gets ignored!
+    }
+    for (auto const& nonFlake : deps.nonFlakes) {
+        FlakeRegistry::Entry entry = FlakeRegistry::Entry(nonFlake.ref);
+        newLockFile.entries.insert_or_assign(nonFlake.id, entry);
+        // We are assuming the sets of FlakeIds for flakes and non-flakes
+        // are disjoint.
     }
     return newLockFile;
 }
@@ -348,21 +382,26 @@ void updateLockFile(EvalState & state, std::string path)
     }
 }
 
-Value * makeFlakeValue(EvalState & state, const FlakeRef & flakeRef, bool impureTopRef, Value & v)
+// Return the `provides` of the top flake, while assigning to `v` the provides
+// of the dependencies as well.
+Value * makeFlakeValue(EvalState & state, FlakeUri flakeUri, bool impureTopRef, Value & v)
 {
-    auto [topFlakeId, flakes] = resolveFlake(state, flakeRef, impureTopRef);
+    FlakeRef flakeRef = FlakeRef(flakeUri);
+
+    Dependencies deps = resolveFlake(state, flakeRef, impure);
 
     // FIXME: we should call each flake with only its dependencies
     // (rather than the closure of the top-level flake).
 
     auto vResult = state.allocValue();
+    // This will store the attribute set of the `nonFlakeRequires` and the `requires.provides`.
 
-    state.mkAttrs(*vResult, flakes.size());
+    state.mkAttrs(*vResult, dependencies.flakes.size());
 
     Value * vTop = 0;
 
-    for (auto & flake : flakes) {
-        auto vFlake = state.allocAttr(*vResult, flake.second.id);
+    for (auto & flake : deps.flakes) {
+        auto vFlake = state.allocAttr(*vResult, flake.id);
         if (topFlakeId == flake.second.id) vTop = vFlake;
 
         state.mkAttrs(*vFlake, 4);
diff --git a/src/libexpr/primops/flake.hh b/src/libexpr/primops/flake.hh
index aea4e8aa2..ffd962561 100644
--- a/src/libexpr/primops/flake.hh
+++ b/src/libexpr/primops/flake.hh
@@ -38,15 +38,34 @@ struct Flake
     std::optional<uint64_t> revCount;
     std::vector<FlakeRef> requires;
     std::shared_ptr<FlakeRegistry> lockFile;
+    std::map<FlakeId, FlakeRef> nonFlakeRequires;
     Value * vProvides; // FIXME: gc
-    // commit hash
     // date
     // content hash
-    Flake(FlakeRef & flakeRef) : ref(flakeRef) {};
+    Flake(const FlakeRef flakeRef) : ref(flakeRef) {};
+};
+
+struct NonFlake
+{
+    FlakeId id;
+    FlakeRef ref;
+    Path path;
+    // date
+    // content hash
+    NonFlake(const FlakeRef flakeRef) : ref(flakeRef) {};
 };
 
 Flake getFlake(EvalState &, const FlakeRef &);
 
+struct Dependencies
+{
+    FlakeId topFlakeId;
+    std::vector<Flake> flakes;
+    std::vector<NonFlake> nonFlakes;
+};
+
+Dependencies resolveFlake(EvalState &, const FlakeRef &, bool impureTopRef);
+
 FlakeRegistry updateLockFile(EvalState &, Flake &);
 
 void updateLockFile(EvalState &, std::string);
diff --git a/src/nix/build.cc b/src/nix/build.cc
index da7c7f614..a6fcf5094 100644
--- a/src/nix/build.cc
+++ b/src/nix/build.cc
@@ -11,7 +11,7 @@ struct CmdBuild : MixDryRun, InstallablesCommand
 {
     Path outLink = "result";
 
-    std::optional<std::string> gitRepo = std::nullopt;
+    bool updateLock = true;
 
     CmdBuild()
     {
@@ -28,9 +28,9 @@ struct CmdBuild : MixDryRun, InstallablesCommand
             .set(&outLink, Path(""));
 
         mkFlag()
-            .longName("update-lock-file")
-            .description("update the lock file")
-            .dest(&gitRepo);
+            .longName("no-update")
+            .description("don't update the lock file")
+            .set(&updateLock, false);
     }
 
     std::string name() override
@@ -78,8 +78,10 @@ struct CmdBuild : MixDryRun, InstallablesCommand
                     }
         }
 
-        if (gitRepo)
-            updateLockFile(*evalState, *gitRepo);
+        if(updateLock)
+            for (int i = 0; i < installables.size(); i++)
+                if (auto flakeUri = installableToFlakeUri)
+                    updateLockFile(*evalState, FlakeRef(*flakeUri));
     }
 };
 
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 3d2fb7832..07d31c45a 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -36,6 +36,60 @@ struct CmdFlakeList : StoreCommand, MixEvalArgs
     }
 };
 
+void printFlakeInfo(Flake & flake, bool json) {
+    if (json) {
+        nlohmann::json j;
+        j["name"] = flake.id;
+        j["location"] = flake.path;
+        j["description"] = flake.description;
+        std::cout << j.dump(4) << std::endl;
+    } else {
+        std::cout << "Name:        " << flake.id << "\n";
+        std::cout << "Description: " << flake.description << "\n";
+        std::cout << "Location:    " << flake.path << "\n";
+    }
+}
+
+void printNonFlakeInfo(NonFlake & nonFlake, bool json) {
+    if (json) {
+        nlohmann::json j;
+        j["name"] = nonFlake.id;
+        j["location"] = nonFlake.path;
+        std::cout << j.dump(4) << std::endl;
+    } else {
+        std::cout << "name:        " << nonFlake.id << "\n";
+        std::cout << "Location:    " << nonFlake.path << "\n";
+    }
+}
+
+struct CmdFlakeDeps : FlakeCommand, MixJSON, StoreCommand, MixEvalArgs
+{
+    std::string name() override
+    {
+        return "deps";
+    }
+
+    std::string description() override
+    {
+        return "list informaton about dependencies";
+    }
+
+    void run(nix::ref<nix::Store> store) override
+    {
+        auto evalState = std::make_shared<EvalState>(searchPath, store);
+
+        FlakeRef flakeRef(flakeUri);
+
+        Dependencies deps = resolveFlake(*evalState, flakeRef, true);
+
+        for (auto & flake : deps.flakes)
+            printFlakeInfo(flake, json);
+
+        for (auto & nonFlake : deps.nonFlakes)
+            printNonFlakeInfo(nonFlake, json);
+    }
+};
+
 struct CmdFlakeUpdate : StoreCommand, GitRepoCommand, MixEvalArgs
 {
     std::string name() override
@@ -73,15 +127,7 @@ struct CmdFlakeInfo : FlakeCommand, MixJSON, MixEvalArgs, StoreCommand
     {
         auto evalState = std::make_shared<EvalState>(searchPath, store);
         nix::Flake flake = nix::getFlake(*evalState, FlakeRef(flakeUri));
-        if (json) {
-            nlohmann::json j;
-            j["location"] = flake.path;
-            j["description"] = flake.description;
-            std::cout << j.dump(4) << std::endl;
-        } else {
-            std::cout << "Description: " << flake.description << "\n";
-            std::cout << "Location:    " << flake.path << "\n";
-        }
+        printFlakeInfo(flake, json);
     }
 };
 
@@ -218,6 +264,7 @@ struct CmdFlake : virtual MultiCommand, virtual Command
         : MultiCommand({make_ref<CmdFlakeList>()
             , make_ref<CmdFlakeUpdate>()
             , make_ref<CmdFlakeInfo>()
+            , make_ref<CmdFlakeDeps>()
             , make_ref<CmdFlakeAdd>()
             , make_ref<CmdFlakeRemove>()
             , make_ref<CmdFlakePin>()