libnixt: omit AST header in Deserialize

nix-community · Mar 14, 2024 · 330850a · 330850a
1 parent 3a8fc1f
commit 330850a
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Showing 3 changed files with 46 additions and 36 deletions.
diff --git a/libnixt/include/nixt/Deserialize.h b/libnixt/include/nixt/Deserialize.h
@@ -3,19 +3,37 @@
 #include "HookExpr.h"
 #include "PtrPool.h"
 
+#include <nix/input-accessor.hh>
 #include <nix/nixexpr.hh>
 
 #include <string_view>
 
 namespace nixt {
 
+/// \brief API Wrapper around nix::
+///
+/// Paths related to this context is very unstable.
 struct DeserializeContext {
-  PtrPool<nix::Expr> &Pool;
   nix::SymbolTable &STable;
   nix::PosTable &PTable;
+
+  /// Path resolution
+  const nix::SourcePath BasePath;
+  const nix::ref<nix::InputAccessor> RootFS;
+
+  const nix::Pos::Origin &Origin;
 };
 
+/// \brief Stable API wrapper around official nix.
+///
+/// Because of "lazy-trees", these APIs have always breaked among nix updates,
+/// the function wraps the context with a "stable" class `nix::EvalState`.
+DeserializeContext getDeserializeContext(nix::EvalState &State,
+                                         std::string_view BasePath,
+                                         const nix::Pos::Origin &Origin);
+
 nix::Expr *deserializeHookable(std::string_view &Data, DeserializeContext &Ctx,
-                               ValueMap &VMap, EnvMap &EMap);
+                               PtrPool<nix::Expr> &Pool, ValueMap &VMap,
+                               EnvMap &EMap);
 
 } // namespace nixt
diff --git a/libnixt/lib/ASTReader.cpp b/libnixt/lib/ASTReader.cpp
@@ -9,21 +9,19 @@
 
 #include <bc/Read.h>
 
-#include <memory>
+#include <nix/eval.hh>
+#include <nix/fs-input-accessor.hh>
 
 namespace nixt {
 
 using namespace nixbc;
-using bc::readBytecode;
-
 nix::Expr *ASTDeserializer::eatHookable(std::string_view &Data, ValueMap &VMap,
                                         EnvMap &EMap) {
-  auto Kind = eat<ExprKind>(Data);
-  switch (Kind) {
+  auto Hdr = eat<NodeHeader>(Data);
+  switch (Hdr.Kind) {
   case EK_Int: {
-    auto Handle = eat<std::uintptr_t>(Data);
-    return Ctx.Pool.record(
-        new HookExprInt(eatExprInt(Data), VMap, EMap, Handle));
+    return Pool.record(
+        new HookExprInt(eatExprInt(Data), VMap, EMap, Hdr.Handle));
   }
   default:
     break;
@@ -41,32 +39,26 @@ nix::ExprInt ASTDeserializer::eatExprInt(std::string_view &Data) {
   return {eat<NixInt>(Data)};
 }
 
-nix::Expr *deserializeHookable(std::string_view &Data, DeserializeContext &Ctx,
-                               ValueMap &VMap, EnvMap &EMap) {
-  FileHeader Hdr;
-  readBytecode(Data, Hdr);
-  assert(Hdr.Magic == FileHeader::MagicValue && "Invalid magic value");
-  assert(Hdr.Version == 1 && "Invalid version value");
+DeserializeContext getDeserializeContext(nix::EvalState &State,
+                                         std::string_view BasePath,
+                                         const nix::Pos::Origin &Origin) {
+  auto Base = State.rootPath(nix::CanonPath(BasePath));
+  const nix::ref<nix::InputAccessor> RootFS = State.rootFS;
 
-  // Deserialize "Origin"
-  Origin::OriginKind Kind;
-  readBytecode(Data, Kind);
-  nix::Pos::Origin O;
-  switch (Kind) {
-  case Origin::OK_Path: {
-    OriginPath Path;
-    readBytecode(Data, Path);
-    // TODO
-    break;
-  }
-  case Origin::OK_None:
-  case Origin::OK_Stdin:
-  case Origin::OK_String:
-    break;
-  }
+  // Filling the context.
+  // These are required for constructing evaluable nix ASTs
+  return {.STable = State.symbols,
+          .PTable = State.positions,
+          .BasePath = Base,
+          .RootFS = RootFS,
+          .Origin = Origin};
+}
 
+nix::Expr *deserializeHookable(std::string_view &Data, DeserializeContext &Ctx,
+                               PtrPool<nix::Expr> &Pool, ValueMap &VMap,
+                               EnvMap &EMap) {
   // Deserialize "Hookable"
-  ASTDeserializer D(Ctx, O);
+  ASTDeserializer D(Ctx, Pool);
   return D.eatHookable(Data, VMap, EMap);
 }
 

diff --git a/libnixt/lib/ASTReader.h b/libnixt/lib/ASTReader.h
@@ -12,13 +12,13 @@ namespace nixt {
 
 class ASTDeserializer {
   DeserializeContext &Ctx;
-  [[maybe_unused]] nix::Pos::Origin &Origin;
+  PtrPool<nix::Expr> &Pool;
 
   template <class T> T eat(std::string_view &Data) { return bc::eat<T>(Data); }
 
 public:
-  ASTDeserializer(DeserializeContext &Ctx, nix::Pos::Origin &Origin)
-      : Ctx(Ctx), Origin(Origin) {}
+  ASTDeserializer(DeserializeContext &Ctx, PtrPool<nix::Expr> &Pool)
+      : Ctx(Ctx), Pool(Pool) {}
 
   nix::Expr *eatHookable(std::string_view &Data, ValueMap &VMap, EnvMap &EMap);