Optimize small lists

The value pointers of lists with 1 or 2 elements are now stored in the
list value itself. In particular, this makes the "concatMap (x: if
cond then [(f x)] else [])" idiom cheaper.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 04f1016167a9..97a2bbdb7de0 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -1127,13 +1127,13 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
                                     attrs2["type"] = "bool";
                                     attrs2["value"] = v->boolean ? "true" : "false";
                                     xml.writeEmptyElement("meta", attrs2);
-                                } else if (v->type == tList) {
+                                } else if (v->isList()) {
                                     attrs2["type"] = "strings";
                                     XMLOpenElement m(xml, "meta", attrs2);
-                                    for (unsigned int j = 0; j < v->list.length; ++j) {
-                                        if (v->list.elems[j]->type != tString) continue;
+                                    for (unsigned int j = 0; j < v->listSize(); ++j) {
+                                        if (v->listElems()[j]->type != tString) continue;
                                         XMLAttrs attrs3;
-                                        attrs3["value"] = v->list.elems[j]->string.s;
+                                        attrs3["value"] = v->listElems()[j]->string.s;
                                         xml.writeEmptyElement("string", attrs3);
                                     }
                                 }