Package.use: share identical frozenset instances

diff --git a/pym/_emerge/Package.py b/pym/_emerge/Package.py
index 7a25638c83235217eafa17bf5b23595b987f76fb..20c72b481c0343358c1de122fa41c78b7d85d449 100644 (file)
--- a/pym/_emerge/Package.py
+++ b/pym/_emerge/Package.py
@@ -392,6 +392,9 @@ class Package(Task):
                __slots__ = ("enabled", "_expand", "_expand_hidden",
                        "_force", "_pkg", "_mask")
 
+               # Share identical frozenset instances when available.
+               _frozensets = {}
+
                def __init__(self, pkg, use_str):
                        self._pkg = pkg
                        self._expand = None
@@ -410,12 +413,17 @@ class Package(Task):
 
                def _init_force_mask(self):
                        pkgsettings = self._pkg._get_pkgsettings()
-                       self._expand = frozenset(
+                       frozensets = self._frozensets
+                       s = frozenset(
                                pkgsettings.get("USE_EXPAND", "").lower().split())
-                       self._expand_hidden = frozenset(
+                       self._expand = frozensets.setdefault(s, s)
+                       s = frozenset(
                                pkgsettings.get("USE_EXPAND_HIDDEN", "").lower().split())
-                       self._force = pkgsettings.useforce
-                       self._mask = pkgsettings.usemask
+                       self._expand_hidden = frozensets.setdefault(s, s)
+                       s = pkgsettings.useforce
+                       self._force = frozensets.setdefault(s, s)
+                       s = pkgsettings.usemask
+                       self._mask = frozensets.setdefault(s, s)
 
                @property
                def expand(self):