From 04c4bd3624b094043ff0f2410c1e376a51f457f7 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Thu, 15 Apr 2010 00:37:36 +0000
Subject: * Store lists as lists of pointers to values rather than as lists of 
  values.  This improves sharing and gives another speed up.   Evaluation of
 the NixOS system attribute is now almost 7 times   faster than the old
 evaluator.

---
 src/libexpr/primops.cc | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

(limited to 'src/libexpr/primops.cc')

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 0d7459feef46..ae17506ceed9 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -311,7 +311,7 @@ static void prim_derivationStrict(EvalState & state, Value * * args, Value & v)
             if (key == "args") {
                 state.forceList(i->second);
                 for (unsigned int n = 0; n < i->second.list.length; ++n) {
-                    string s = state.coerceToString(i->second.list.elems[n], context, true);
+                    string s = state.coerceToString(*i->second.list.elems[n], context, true);
                     drv.args.push_back(s);
                 }
             }
@@ -651,14 +651,17 @@ static void prim_attrNames(EvalState & state, Value * * args, Value & v)
     state.forceAttrs(*args[0]);
 
     state.mkList(v, args[0]->attrs->size());
+    Value * vs = state.allocValues(v.list.length);
 
     StringSet names;
     foreach (Bindings::iterator, i, *args[0]->attrs)
         names.insert(i->first);
 
     unsigned int n = 0;
-    foreach (StringSet::iterator, i, names)
-        mkString(v.list.elems[n++], *i);
+    foreach (StringSet::iterator, i, names) {
+        v.list.elems[n] = &vs[n];
+        mkString(vs[n++], *i);
+    }
 }
 
 
@@ -701,8 +704,8 @@ static void prim_removeAttrs(EvalState & state, Value * * args, Value & v)
     state.cloneAttrs(*args[0], v);
 
     for (unsigned int i = 0; i < args[1]->list.length; ++i) {
-        state.forceStringNoCtx(args[1]->list.elems[i]);
-        v.attrs->erase(state.symbols.create(args[1]->list.elems[i].string.s));
+        state.forceStringNoCtx(*args[1]->list.elems[i]);
+        v.attrs->erase(state.symbols.create(args[1]->list.elems[i]->string.s));
     }
 }
 
@@ -718,7 +721,7 @@ static void prim_listToAttrs(EvalState & state, Value * * args, Value & v)
     state.mkAttrs(v);
 
     for (unsigned int i = 0; i < args[0]->list.length; ++i) {
-        Value & v2(args[0]->list.elems[i]);
+        Value & v2(*args[0]->list.elems[i]);
         state.forceAttrs(v2);
         
         Bindings::iterator j = v2.attrs->find(state.sName);
@@ -815,8 +818,8 @@ static void prim_head(EvalState & state, Value * * args, Value & v)
     state.forceList(*args[0]);
     if (args[0]->list.length == 0)
         throw Error("`head' called on an empty list");
-    state.forceValue(args[0]->list.elems[0]);
-    v = args[0]->list.elems[0];
+    state.forceValue(*args[0]->list.elems[0]);
+    v = *args[0]->list.elems[0];
 }
 
 
@@ -840,11 +843,13 @@ static void prim_map(EvalState & state, Value * * args, Value & v)
     state.forceList(*args[1]);
 
     state.mkList(v, args[1]->list.length);
+    Value * vs = state.allocValues(v.list.length);
 
     for (unsigned int n = 0; n < v.list.length; ++n) {
-        v.list.elems[n].type = tApp;
-        v.list.elems[n].app.left = args[0];
-        v.list.elems[n].app.right = &args[1]->list.elems[n];
+        v.list.elems[n] = &vs[n];
+        vs[n].type = tApp;
+        vs[n].app.left = args[0];
+        vs[n].app.right = args[1]->list.elems[n];
     }
 }
 
-- 
cgit 1.4.1