optimize removeAttrs builtin

use a sorted array of symbols to be removed instead of a set. this saves a lot
of memory allocations and slightly speeds up removal.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/libexpr/attr-set.hh b/src/libexpr/attr-set.hh
index 82c348287..3e4899efc 100644
--- a/src/libexpr/attr-set.hh
+++ b/src/libexpr/attr-set.hh
@@ -121,6 +121,8 @@ class BindingsBuilder
     Bindings * bindings;
 
 public:
+    // needed by std::back_inserter
+    using value_type = Attr;
 
     EvalState & state;
 
@@ -135,6 +137,11 @@ public:
 
     void insert(const Attr & attr)
     {
+        push_back(attr);
+    }
+
+    void push_back(const Attr & attr)
+    {
         bindings->push_back(attr);
     }