Bindings: Add a method for iterating in lexicographically sorted order

4 files changed, 28 insertions, 28 deletions

diff --git a/src/libexpr/attr-set.hh b/src/libexpr/attr-set.hh
index 7cf6a9c58086..e1fc2bf6d796 100644
--- a/src/libexpr/attr-set.hh
+++ b/src/libexpr/attr-set.hh
@@ -75,6 +75,19 @@ public:
 
     size_t capacity() { return capacity_; }
 
+    /* Returns the attributes in lexicographically sorted order. */
+    std::vector<const Attr *> lexicographicOrder() const
+    {
+        std::vector<const Attr *> res;
+        res.reserve(size_);
+        for (size_t n = 0; n < size_; n++)
+            res.emplace_back(&attrs[n]);
+        std::sort(res.begin(), res.end(), [](const Attr * a, const Attr * b) {
+            return (string) a->name < (string) b->name;
+        });
+        return res;
+    }
+
     friend class EvalState;
 };
 
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 64f3874db614..5f9f5bac1ed6 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -91,13 +91,9 @@ static void printValue(std::ostream & str, std::set<const Value *> & active, con
         break;
     case tAttrs: {
         str << "{ ";
-        typedef std::map<string, Value *> Sorted;
-        Sorted sorted;
-        for (auto & i : *v.attrs)
-            sorted[i.name] = i.value;
-        for (auto & i : sorted) {
-            str << i.first << " = ";
-            printValue(str, active, *i.second);
+        for (auto & i : v.attrs->lexicographicOrder()) {
+            str << i->name << " = ";
+            printValue(str, active, *i->value);
             str << "; ";
         }
         str << "}";
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index dc5def911ca0..5342739c53c4 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -284,25 +284,19 @@ static void getDerivations(EvalState & state, Value & vIn,
            there are names clashes between derivations, the derivation
            bound to the attribute with the "lower" name should take
            precedence). */
-        typedef std::map<string, Symbol> SortedSymbols;
-        SortedSymbols attrs;
-        for (auto & i : *v.attrs)
-            attrs.insert(std::pair<string, Symbol>(i.name, i.name));
-
-        for (auto & i : attrs) {
-            Activity act(*logger, lvlDebug, format("evaluating attribute ‘%1%’") % i.first);
-            string pathPrefix2 = addToPath(pathPrefix, i.first);
-            Value & v2(*v.attrs->find(i.second)->value);
+        for (auto & i : v.attrs->lexicographicOrder()) {
+            Activity act(*logger, lvlDebug, format("evaluating attribute ‘%1%’") % i->name);
+            string pathPrefix2 = addToPath(pathPrefix, i->name);
             if (combineChannels)
-                getDerivations(state, v2, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
-            else if (getDerivation(state, v2, pathPrefix2, drvs, done, ignoreAssertionFailures)) {
+                getDerivations(state, *i->value, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
+            else if (getDerivation(state, *i->value, pathPrefix2, drvs, done, ignoreAssertionFailures)) {
                 /* If the value of this attribute is itself a set,
                    should we recurse into it?  => Only if it has a
                    `recurseForDerivations = true' attribute. */
-                if (v2.type == tAttrs) {
-                    Bindings::iterator j = v2.attrs->find(state.symbols.create("recurseForDerivations"));
-                    if (j != v2.attrs->end() && state.forceBool(*j->value, *j->pos))
-                        getDerivations(state, v2, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
+                if (i->value->type == tAttrs) {
+                    Bindings::iterator j = i->value->attrs->find(state.symbols.create("recurseForDerivations"));
+                    if (j != i->value->attrs->end() && state.forceBool(*j->value, *j->pos))
+                        getDerivations(state, *i->value, pathPrefix2, autoArgs, drvs, done, ignoreAssertionFailures);
                 }
             }
         }
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 59623874c3f5..d8dbedcaf89e 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -998,12 +998,9 @@ static void prim_attrNames(EvalState & state, const Pos & pos, Value * * args, V
 
     state.mkList(v, args[0]->attrs->size());
 
-    unsigned int n = 0;
-    for (auto & i : *args[0]->attrs)
-        mkString(*(v.listElems()[n++] = state.allocValue()), i.name);
-
-    std::sort(v.listElems(), v.listElems() + n,
-        [](Value * v1, Value * v2) { return strcmp(v1->string.s, v2->string.s) < 0; });
+    size_t n = 0;
+    for (auto & i : args[0]->attrs->lexicographicOrder())
+        mkString(*(v.listElems()[n++] = state.allocValue()), i->name);
 }