From 6eb1a2415c97ef576e9d46f3c5d13c7e8c2b6916 Mon Sep 17 00:00:00 2001
From: Yingchi Long <i@lyc.dev>
Date: Fri, 26 Apr 2024 18:06:43 +0800
Subject: [PATCH] {libnixt,nixd/Eval}: support `attrsOf submodule` (#465)

Currently these options are nested under

`foo.bar.<name>.options`

Fixes: #106
---
 libnixt/include/nixt/Value.h      | 13 ++++++++++
 libnixt/lib/Value.cpp             | 42 +++++++++++++++++++++++++++++++
 nixd/lib/Eval/AttrSetProvider.cpp |  6 +++--
 3 files changed, 59 insertions(+), 2 deletions(-)

diff --git a/libnixt/include/nixt/Value.h b/libnixt/include/nixt/Value.h
index 3e7717f34..5e5ec02b2 100644
--- a/libnixt/include/nixt/Value.h
+++ b/libnixt/include/nixt/Value.h
@@ -33,11 +33,24 @@ std::vector<nix::Symbol> toSymbols(nix::SymbolTable &STable,
 /// \brief Select attribute \p Attr
 nix::Value &selectAttr(nix::EvalState &State, nix::Value &V, nix::Symbol Attr);
 
+nix::Value &selectOption(nix::EvalState &State, nix::Value &V,
+                         nix::Symbol Attr);
+
 /// \brief Given an attrpath in nix::Value \p V, select it
 nix::Value &selectAttrPath(nix::EvalState &State, nix::Value &V,
                            std::vector<nix::Symbol>::const_iterator Begin,
                            std::vector<nix::Symbol>::const_iterator End);
 
+/// \brief Select the option declaration list, \p V,  dive into "submodules".
+nix::Value &selectOptions(nix::EvalState &State, nix::Value &V,
+                          std::vector<nix::Symbol>::const_iterator Begin,
+                          std::vector<nix::Symbol>::const_iterator End);
+
+inline nix::Value &selectOptions(nix::EvalState &State, nix::Value &V,
+                                 const std::vector<nix::Symbol> &AttrPath) {
+  return selectOptions(State, V, AttrPath.begin(), AttrPath.end());
+}
+
 /// \copydoc selectAttrPath
 inline nix::Value &selectSymbols(nix::EvalState &State, nix::Value &V,
                                  const std::vector<nix::Symbol> &AttrPath) {
diff --git a/libnixt/lib/Value.cpp b/libnixt/lib/Value.cpp
index c9a23336f..b776507a5 100644
--- a/libnixt/lib/Value.cpp
+++ b/libnixt/lib/Value.cpp
@@ -109,3 +109,45 @@ nix::Value &nixt::selectAttrPath(nix::EvalState &State, nix::Value &V,
   nix::Value &Nested = selectAttr(State, V, *Begin);
   return selectAttrPath(State, Nested, ++Begin, End);
 }
+
+nix::Value &nixt::selectOptions(nix::EvalState &State, nix::Value &V,
+                                std::vector<nix::Symbol>::const_iterator Begin,
+                                std::vector<nix::Symbol>::const_iterator End) {
+  if (Begin == End)
+    return V;
+
+  if (isOption(State, V)) {
+    // If currently "V" is an option, it can still be submodules.
+    //
+    // e.g. users.users <-- the main option stops at here.
+    //      networking.interfaces
+    //
+    // Take care of such case.
+    nix::Value &Type = selectAttr(State, V, State.sType);
+    if (checkField(State, Type, "name", "attrsOf")) {
+      nix::Value NestedTypes =
+          selectAttr(State, Type, State.symbols.create("nestedTypes"));
+      nix::Value ElemType =
+          selectAttr(State, NestedTypes, State.symbols.create("elemType"));
+
+      if (checkField(State, ElemType, "name", "submodule")) {
+        // Current iterator may be ommited, and V becomes "V.getSubOptions []"
+        nix::Value &GetSubOptions =
+            selectAttr(State, ElemType, State.symbols.create("getSubOptions"));
+
+        nix::Value EmptyList;
+        EmptyList.mkList(0);
+
+        // Invoke "GetSubOptions"
+        nix::Value Next;
+        State.callFunction(GetSubOptions, EmptyList, Next, nix::noPos);
+
+        return selectOptions(State, Next, ++Begin, End);
+      }
+    }
+  }
+
+  // Otherwise, simply select it.
+  nix::Value &Nested = selectAttr(State, V, *Begin);
+  return selectOptions(State, Nested, ++Begin, End);
+}
diff --git a/nixd/lib/Eval/AttrSetProvider.cpp b/nixd/lib/Eval/AttrSetProvider.cpp
index 1607d7d41..2397c6f1d 100644
--- a/nixd/lib/Eval/AttrSetProvider.cpp
+++ b/nixd/lib/Eval/AttrSetProvider.cpp
@@ -232,7 +232,8 @@ void AttrSetProvider::onOptionInfo(
       return;
     }
 
-    nix::Value &Option = nixt::selectStrings(state(), Nixpkgs, AttrPath);
+    nix::Value &Option = nixt::selectOptions(
+        state(), Nixpkgs, nixt::toSymbols(state().symbols, AttrPath));
 
     OptionInfoResponse R;
 
@@ -253,7 +254,8 @@ void AttrSetProvider::onOptionComplete(
     const AttrPathCompleteParams &Params,
     lspserver::Callback<OptionCompleteResponse> Reply) {
   try {
-    nix::Value &Scope = nixt::selectStrings(state(), Nixpkgs, Params.Scope);
+    nix::Value &Scope = nixt::selectOptions(
+        state(), Nixpkgs, nixt::toSymbols(state().symbols, Params.Scope));
 
     state().forceValue(Scope, nix::noPos);