From b2bc3390413f7fdfdd2baabd2c244576fa31fc58 Mon Sep 17 00:00:00 2001
From: David Leen <daleen@gmail.com>
Date: Tue, 17 Jun 2014 21:42:55 -0700
Subject: [PATCH] Add a class for interacting with git config

This commit adds the GitConfigStore class. This allows us to easily
get and set keys and values in git config.

Tests pass.
---
 git-imerge | 81 ++++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 66 insertions(+), 15 deletions(-)

diff --git a/git-imerge b/git-imerge
index 897a48b..eb8b459 100755
--- a/git-imerge
+++ b/git-imerge
@@ -580,6 +580,67 @@ class AutomaticMergeFailed(Exception):
         self.commit1, self.commit2 = commit1, commit2
 
 
+class GitConfigError(Exception):
+    def __init__(self, returncode, output):
+        Exception.__init__(
+            self, 'Git config failed with exit code %s: %s' % (returncode, output,)
+            )
+
+
+def memo(obj):
+    cache = {}
+    @functools.wraps(obj)
+    def wrap(*args, **kwds):
+        if args not in cache:
+            cache[args] = obj(*args, **kwds)
+        return cache[args]
+    return wrap
+
+
+@memo
+class GitConfigStore(object):
+    def __init__(self, name, config_prefix='imerge'):
+        self.config_prefix = config_prefix
+        self.config = self._get_all_keys()
+
+    def _get_all_keys(self):
+        d = {}
+        try:
+            items_with_prefix = check_output(
+                ['git', 'config', '--get-regex', self.config_prefix]
+                ).rstrip().split('\n')
+            for row in items_with_prefix:
+                k, v = row.split()
+                d[k[len(self.config_prefix + '.'):]] = v
+            return d
+        except CalledProcessError:
+            return {}
+
+    def get(self, key):
+        return self.config.get(key)
+
+    def set(self, key, value):
+        self.config[key] = value
+        config_key = '.'.join([self.config_prefix, key])
+        try:
+            check_call(['git', 'config', config_key, value])
+        except CalledProcessError as e:
+            raise GitConfigError(e.returncode, e.output)
+
+    def unset(self, key):
+        if key in self.config:
+            del self.config[key]
+        config_key = '.'.join([self.config_prefix, key])
+        try:
+            check_call(['git', 'config', '--unset', config_key])
+        except CalledProcessError as e:
+            if e.returncode == 5:
+                # Value was not set
+                pass
+            else:
+                raise GitConfigError(e.returncode, e.output)
+
+
 def automerge(commit1, commit2, msg=None):
     """Attempt an automatic merge of commit1 and commit2.
 
@@ -1865,27 +1926,17 @@ class MergeState(Block):
         """Set the default merge to the specified one.
 
         name can be None to cause the default to be cleared."""
-
+        gcs = GitConfigStore(name)
         if name is None:
-            try:
-                check_call(['git', 'config', '--unset', 'imerge.default'])
-            except CalledProcessError as e:
-                if e.returncode == 5:
-                    # Value was not set
-                    pass
-                else:
-                    raise
+            gcs.unset("default")
         else:
-            check_call(['git', 'config', 'imerge.default', name])
+            gcs.set("default", name)
 
     @staticmethod
     def get_default_name():
         """Get the name of the default merge, or None if none is currently set."""
-
-        try:
-            return check_output(['git', 'config', 'imerge.default']).rstrip()
-        except CalledProcessError:
-            return None
+        gcs = GitConfigStore(None)
+        return gcs.get("default")
 
     @staticmethod
     def _check_no_merges(commits):