Subreddit AllMinus that subtracts from /r/all.

r2/r2/controllers/reddit_base.py

@@ -78,6 +78,7 @@ from r2.lib.validator import (
 )
 from r2.models import (
     All,
+    AllMinus,
     check_request,
     DefaultSR,
     DomainSR,
@@ -338,6 +339,16 @@ def set_subreddit():
             else:
                 sr_ids = [sr._id for sr in srs]
                 c.site = MultiReddit(sr_ids, sr_name)
+    elif '-' in sr_name:
+        sr_names = sr_name.split('-')
+        if not sr_names[0].lower() == All.name.lower():
+            abort(404)
+        srs = Subreddit._by_name(sr_names[1:], stale=can_stale).values()
+        srs = [sr for sr in srs if not isinstance(sr, FakeSubreddit)]
+        if not srs:
+            c.site = All
+        else:
+            c.site = AllMinus(srs)
     else:
         try:
             c.site = Subreddit._by_name(sr_name, stale=can_stale)

r2/r2/models/subreddit.py

@@ -973,6 +973,29 @@ class AllSR(FakeSubreddit):
         return None
 
 
+class AllMinus(AllSR):
+    name = 'minus'
+
+    def __init__(self, srs):
+        AllSR.__init__(self)
+        self.srs = srs
+        self.sr_ids = [sr._id for sr in srs]
+
+    @property
+    def title(self):
+        return 'all minus ' + ' '.join(sr.name for sr in self.srs)
+
+    @property
+    def path(self):
+        return '/r/all-' + '-'.join(sr.name for sr in self.srs)
+
+    def get_links(self, sort, time):
+        from r2.models import Link
+        from r2.lib.db.operators import not_
+        q = AllSR.get_links(self, sort, time)
+        q._filter(not_(Link.c.sr_id.in_(self.sr_ids)))
+        return q
+
 class _DefaultSR(FakeSubreddit):
     #notice the space before reddit.com
     name = ' reddit.com'