[diffoscope] 01/02: Move 'container with one member' logic into separate class.

[Maria Glukhova]

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siamezzze-guest pushed a commit to branch siamezzze/containers
in repository diffoscope.

commit 926abd82bca355d55333ffad88f2dea3cba23b15
Author: Maria Glukhova <siamezzze at gmail.com>
Date:   Thu Feb 16 23:14:28 2017 +0200

    Move 'container with one member' logic into separate class.
    
    Create OneMenberContainer class, that incapsulates the logic of
    container having only one member. It has the ability (get_nested_container)
    to check if this only member is also a container, and in such case,
    return this inner container.
    Change Bzip2Container, GzipContainer and XzContainer to use this
    class, avoiding DRY violations.
---
 diffoscope/comparators/bzip2.py           | 12 +++---------
 diffoscope/comparators/gzip.py            | 12 +++---------
 diffoscope/comparators/utils/container.py | 12 ++++++++++++
 diffoscope/comparators/xz.py              | 12 +++---------
 4 files changed, 21 insertions(+), 27 deletions(-)

diff --git a/diffoscope/comparators/bzip2.py b/diffoscope/comparators/bzip2.py
index e8fa96e..98f4b47 100644
--- a/diffoscope/comparators/bzip2.py
+++ b/diffoscope/comparators/bzip2.py
@@ -27,13 +27,13 @@ from diffoscope.tools import tool_required
 
 from .utils.file import File
 from .utils.archive import Archive
+from .utils.container import OneMemberContainer
 from .utils.filenames import get_compressed_content_name
-from .utils.specialize import specialize
 
 logger = logging.getLogger(__name__)
 
 
-class Bzip2Container(Archive):
+class Bzip2Container(Archive, OneMemberContainer):
     def open_archive(self):
         return self
 
@@ -41,17 +41,11 @@ class Bzip2Container(Archive):
         pass
 
     def get_members(self):
-        return collections.OrderedDict({'bzip2-content': self.get_member(self.get_member_names()[0])})
+        return collections.OrderedDict({'bzip2-content': self.get_the_only_member()})
 
     def get_member_names(self):
         return [get_compressed_content_name(self.source.path, '.bz2')]
 
-    def get_nested_container(self):
-        # If the only member of container is also container, return it.
-        only_member = self.get_member(self.get_member_names()[0])
-        specialize(only_member)
-        return only_member.as_container
-
     @tool_required('bzip2')
     def extract(self, member_name, dest_dir):
         dest_path = os.path.join(dest_dir, member_name)
diff --git a/diffoscope/comparators/gzip.py b/diffoscope/comparators/gzip.py
index 2541496..b1f0233 100644
--- a/diffoscope/comparators/gzip.py
+++ b/diffoscope/comparators/gzip.py
@@ -29,13 +29,13 @@ from diffoscope.difference import Difference
 
 from .utils.file import File
 from .utils.archive import Archive
+from .utils.container import OneMemberContainer
 from .utils.filenames import get_compressed_content_name
-from .utils.specialize import specialize
 
 logger = logging.getLogger(__name__)
 
 
-class GzipContainer(Archive):
+class GzipContainer(Archive, OneMemberContainer):
     def open_archive(self):
         return self
 
@@ -43,17 +43,11 @@ class GzipContainer(Archive):
         pass
 
     def get_members(self):
-        return collections.OrderedDict({'gzip-content': self.get_member(self.get_member_names()[0])})
+        return collections.OrderedDict({'gzip-content': self.get_the_only_member()})
 
     def get_member_names(self):
         return [get_compressed_content_name(self.source.path, '.gz')]
 
-    def get_nested_container(self):
-        # If the only member of container is also container, return it.
-        only_member = self.get_member(self.get_member_names()[0])
-        specialize(only_member)
-        return only_member.as_container
-
     @tool_required('gzip')
     def extract(self, member_name, dest_dir):
         dest_path = os.path.join(dest_dir, member_name)
diff --git a/diffoscope/comparators/utils/container.py b/diffoscope/comparators/utils/container.py
index b5cb97c..ffb1f5a 100644
--- a/diffoscope/comparators/utils/container.py
+++ b/diffoscope/comparators/utils/container.py
@@ -28,6 +28,7 @@ from diffoscope.progress import Progress
 from ..missing_file import MissingFile
 
 from .fuzzy import perform_fuzzy_matching
+from .specialize import specialize
 
 NO_COMMENT = None
 
@@ -168,3 +169,14 @@ class MissingContainer(Container):
 
     def get_member(self, member_name):
         return MissingFile('/dev/null')
+
+
+class OneMemberContainer(Container, metaclass=abc.ABCMeta):
+    def get_the_only_member(self):
+        return self.get_member(self.get_member_names()[0])
+
+    def get_nested_container(self):
+        # If the only member of container is also container, return it.
+        only_member = self.get_the_only_member()
+        specialize(only_member)
+        return only_member.as_container
diff --git a/diffoscope/comparators/xz.py b/diffoscope/comparators/xz.py
index 77edaec..bbd1ad2 100644
--- a/diffoscope/comparators/xz.py
+++ b/diffoscope/comparators/xz.py
@@ -27,13 +27,13 @@ from diffoscope.tools import tool_required
 
 from .utils.file import File
 from .utils.archive import Archive
+from .utils.container import OneMemberContainer
 from .utils.filenames import get_compressed_content_name
-from .utils.specialize import specialize
 
 logger = logging.getLogger(__name__)
 
 
-class XzContainer(Archive):
+class XzContainer(Archive, OneMemberContainer):
     def open_archive(self):
         return self
 
@@ -41,17 +41,11 @@ class XzContainer(Archive):
         pass
 
     def get_members(self):
-        return collections.OrderedDict({'xz-content': self.get_member(self.get_member_names()[0])})
+        return collections.OrderedDict({'xz-content': self.get_the_only_member()})
 
     def get_member_names(self):
         return [get_compressed_content_name(self.source.path, '.xz')]
 
-    def get_nested_container(self):
-        # If the only member of container is also container, return it.
-        only_member = self.get_member(self.get_member_names()[0])
-        specialize(only_member)
-        return only_member.as_container
-
     @tool_required('xz')
     def extract(self, member_name, dest_dir):
         dest_path = os.path.join(dest_dir, member_name)

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