[gentoo-portage-dev] [PATCH v3 1/2] dblink: case insensitive support for bug #524236

[Zac Medico <zmedico@gentoo.org>]

This adds a dblink._contents attribute with methods that provide
an interface for contents operations with "implicit" case handling.
The new methods are implemented in a separate
ContentsCaseSensitivityManager class, in order to avoid adding more
bloat to vartree.py.

X-Gentoo-Bug: 524236
X-Gentoo-Url: https://bugs.gentoo.org/show_bug.cgi?id=524236
---
 .../dbapi/_ContentsCaseSensitivityManager.py       | 93 ++++++++++++++++++++++
 pym/portage/dbapi/vartree.py                       |  3 +
 2 files changed, 96 insertions(+)
 create mode 100644 pym/portage/dbapi/_ContentsCaseSensitivityManager.py

diff --git a/pym/portage/dbapi/_ContentsCaseSensitivityManager.py b/pym/portage/dbapi/_ContentsCaseSensitivityManager.py
new file mode 100644
index 0000000..c479ec9
--- /dev/null
+++ b/pym/portage/dbapi/_ContentsCaseSensitivityManager.py
@@ -0,0 +1,93 @@
+# Copyright 2014 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+class ContentsCaseSensitivityManager(object):
+	"""
+	Implicitly handles case transformations that are needed for
+	case-insensitive support.
+	"""
+
+	def __init__(self, db):
+		"""
+		@param db: A dblink instance
+		@type db: vartree.dblink
+		"""
+		self.getcontents = db.getcontents
+
+		if "case-insensitive-fs" in db.settings.features:
+			self.unmap_key = self._unmap_key_case_insensitive
+			self.contains = self._contains_case_insensitive
+			self.keys = self._keys_case_insensitive
+
+		self._contents_insensitive = None
+		self._reverse_key_map = None
+
+	def clear_cache(self):
+		"""
+		Clear all cached contents data.
+		"""
+		self._contents_insensitive = None
+		self._reverse_key_map = None
+
+	def keys(self):
+		"""
+		Iterate over all contents keys, which are transformed to
+		lowercase when appropriate, for use in case-insensitive
+		comparisons.
+		@rtype: iterator
+		@return: An iterator over all the contents keys
+		"""
+		return iter(self.getcontents())
+
+	def contains(self, key):
+		"""
+		Check if the given key is contained in the contents, using
+		case-insensitive comparison when appropriate.
+		@param key: A filesystem path (including ROOT and EPREFIX)
+		@type key: str
+		@rtype: bool
+		@return: True if the given key is contained in the contents,
+			False otherwise
+		"""
+		return key in self.getcontents()
+
+	def unmap_key(self, key):
+		"""
+		Map a key (from the keys method) back to its case-preserved
+		form.
+		@param key: A filesystem path (including ROOT and EPREFIX)
+		@type key: str
+		@rtype: str
+		@return: The case-preserved form of key
+		"""
+		return key
+
+	def _case_insensitive_init(self):
+		"""
+		Initialize data structures for case-insensitive support.
+		"""
+		self._contents_insensitive = dict(
+			(k.lower(), v) for k, v in self.getcontents().items())
+		self._reverse_key_map = dict(
+			(k.lower(), k) for k in self.getcontents())
+
+	def _keys_case_insensitive(self):
+		if self._contents_insensitive is None:
+			self._case_insensitive_init()
+		return iter(self._contents_insensitive)
+
+	_keys_case_insensitive.__doc__ = keys.__doc__
+
+	def _contains_case_insensitive(self, key):
+		if self._contents_insensitive is None:
+			self._case_insensitive_init()
+		return key.lower() in self._contents_insensitive
+
+	_contains_case_insensitive.__doc__ = contains.__doc__
+
+	def _unmap_key_case_insensitive(self, key):
+		if self._reverse_key_map is None:
+			self._case_insensitive_init()
+		return self._reverse_key_map[key]
+
+	_unmap_key_case_insensitive.__doc__ = unmap_key.__doc__
diff --git a/pym/portage/dbapi/vartree.py b/pym/portage/dbapi/vartree.py
index 8b06f4c..81059b1 100644
--- a/pym/portage/dbapi/vartree.py
+++ b/pym/portage/dbapi/vartree.py
@@ -69,6 +69,7 @@ from _emerge.EbuildPhase import EbuildPhase
 from _emerge.emergelog import emergelog
 from _emerge.MiscFunctionsProcess import MiscFunctionsProcess
 from _emerge.SpawnProcess import SpawnProcess
+from ._ContentsCaseSensitivityManager import ContentsCaseSensitivityManager
 
 import errno
 import fnmatch
@@ -1525,6 +1526,7 @@ class dblink(object):
 		# When necessary, this attribute is modified for
 		# compliance with RESTRICT=preserve-libs.
 		self._preserve_libs = "preserve-libs" in mysettings.features
+		self._contents = ContentsCaseSensitivityManager(self)
 
 	def __hash__(self):
 		return hash(self._hash_key)
@@ -1612,6 +1614,7 @@ class dblink(object):
 		self.contentscache = None
 		self._contents_inodes = None
 		self._contents_basenames = None
+		self._contents.clear_cache()
 
 	def getcontents(self):
 		"""
-- 
2.0.4