don't repeatedly look up ast internal symbols

these symbols are used a *lot*, so it makes sense to cache them. this
mostly increases clarity of the code (however clear one may wish to call
the parser desugaring here), but it also provides a small performance
benefit.

(cherry picked from commit 09a1128d9e2ff0ae6176784938047350d6f8a782)
Change-Id: I73d9f66be4555168e048cb2d542277251580c2d1

1 files changed, 11 insertions, 1 deletions

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 2a6a89ddb..055c0ca3f 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -414,6 +414,16 @@ EvalState::EvalState(
     , sPath(symbols.create("path"))
     , sPrefix(symbols.create("prefix"))
     , sOutputSpecified(symbols.create("outputSpecified"))
+    , exprSymbols{
+        .sub = symbols.create("__sub"),
+        .lessThan = symbols.create("__lessThan"),
+        .mul = symbols.create("__mul"),
+        .div = symbols.create("__div"),
+        .or_ = symbols.create("or"),
+        .findFile = symbols.create("__findFile"),
+        .nixPath = symbols.create("__nixPath"),
+        .body = symbols.create("body")
+    }
     , repair(NoRepair)
     , emptyBindings(0)
     , derivationInternal(rootPath(CanonPath("/builtin/derivation.nix")))
@@ -2815,7 +2825,7 @@ Expr * EvalState::parse(
     const SourcePath & basePath,
     std::shared_ptr<StaticEnv> & staticEnv)
 {
-    auto result = parseExprFromBuf(text, length, origin, basePath, symbols, positions);
+    auto result = parseExprFromBuf(text, length, origin, basePath, symbols, positions, exprSymbols);
 
     result->bindVars(*this, staticEnv);