1 files changed, 69 insertions, 0 deletions
diff --git a/pym/portage/package/ebuild/_config/features_set.py b/pym/portage/package/ebuild/_config/features_set.py
new file mode 100644
index 000000000..e53c2027e
--- /dev/null
+++ b/pym/portage/package/ebuild/_config/features_set.py
@@ -0,0 +1,69 @@
+# Copyright 2010 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+__all__ = (
+	'features_set',
+)
+
+from portage.dep import best_match_to_list
+
+class features_set(object):
+	"""
+	Provides relevant set operations needed for access and modification of
+	config.features. The FEATURES variable is automatically synchronized
+	upon modification.
+
+	Modifications result in a permanent override that will cause the change
+	to propagate to the incremental stacking mechanism in config.regenerate().
+	This eliminates the need to call config.backup_changes() when FEATURES
+	is modified, since any overrides are guaranteed to persist despite calls
+	to config.reset().
+	"""
+
+	def __init__(self, settings):
+		self._settings = settings
+		self._features = set()
+
+	def __contains__(self, k):
+		return k in self._features
+
+	def __iter__(self):
+		return iter(self._features)
+
+	def _sync_env_var(self):
+		self._settings['FEATURES'] = ' '.join(sorted(self._features))
+
+	def add(self, k):
+		self._settings.modifying()
+		self._settings._features_overrides.append(k)
+		if k not in self._features:
+			self._features.add(k)
+			self._sync_env_var()
+
+	def update(self, values):
+		self._settings.modifying()
+		values = list(values)
+		self._settings._features_overrides.extend(values)
+		need_sync = False
+		for k in values:
+			if k in self._features:
+				continue
+			self._features.add(k)
+			need_sync = True
+		if need_sync:
+			self._sync_env_var()
+
+	def remove(self, k):
+		"""
+		This never raises KeyError, since it records a permanent override
+		that will prevent the given flag from ever being added again by
+		incremental stacking in config.regenerate().
+		"""
+		self.discard(k)
+
+	def discard(self, k):
+		self._settings.modifying()
+		self._settings._features_overrides.append('-' + k)
+		if k in self._features:
+			self._features.remove(k)
+			self._sync_env_var()