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authorEelco Dolstra <e.dolstra@tudelft.nl>2010-04-22 15:08:09 +0000
committerEelco Dolstra <e.dolstra@tudelft.nl>2010-04-22 15:08:09 +0000
commit0bc468f195e37a8a5f4f8b36ae6c92459e8ca652 (patch)
treef4057161b6bb181e2899dbe85816e68819327097 /src/libexpr/eval.cc
parentee0384fb966b7a9bd202fa6fb447788be30c4ce4 (diff)
* Simplify the implementation of `with'. This gives a 7% speedup in
evaluating the NixOS system configuration.
Diffstat (limited to 'src/libexpr/eval.cc')
-rw-r--r--src/libexpr/eval.cc34
1 files changed, 9 insertions, 25 deletions
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 9acd42310..b4f12c8a9 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -246,10 +246,14 @@ Value * EvalState::lookupVar(Env * env, const VarRef & var)
for (unsigned int l = var.level; l; --l, env = env->up) ;
if (var.fromWith) {
- Bindings::iterator j = env->values[0].attrs->find(var.name);
- if (j == env->values[0].attrs->end())
- throwEvalError("undefined variable `%1%'", var.name);
- return &j->second;
+ while (1) {
+ Bindings::iterator j = env->values[0].attrs->find(var.name);
+ if (j != env->values[0].attrs->end())
+ return &j->second;
+ if (env->prevWith == 0)
+ throwEvalError("undefined variable `%1%'", var.name);
+ for (unsigned int l = env->prevWith; l; --l, env = env->up) ;
+ }
} else
return &env->values[var.displ];
}
@@ -656,30 +660,10 @@ void ExprWith::eval(EvalState & state, Env & env, Value & v)
{
Env & env2(state.allocEnv(1));
env2.up = &env;
+ env2.prevWith = prevWith;
state.evalAttrs(env, attrs, env2.values[0]);
- /* If there is an enclosing `with', copy all attributes that don't
- appear in this `with'. */
- if (prevWith != -1) {
- Env * env3 = &env;
- for (unsigned int l = prevWith; l; --l, env3 = env3->up) ;
-
- /* Because the first `with' may be a shallow copy of another
- attribute set (through a tCopy node), we need to clone its
- `attrs' before modifying them. */
- Bindings * old(env2.values[0].attrs);
- state.mkAttrs(env2.values[0]);
- foreach (Bindings::iterator, i, *old)
- mkCopy((*env2.values[0].attrs)[i->first], i->second);
-
- foreach (Bindings::iterator, i, *env3->values[0].attrs) {
- Bindings::iterator j = env2.values[0].attrs->find(i->first);
- if (j == env2.values[0].attrs->end())
- mkCopy((*env2.values[0].attrs)[i->first], i->second);
- }
- }
-
state.eval(env2, body, v);
}