Add iscontiguous() and getRange() to IPSet

3 files changed, 74 insertions, 0 deletions

diff --git a/netaddr/ip/sets.py b/netaddr/ip/sets.py
index 0107f74..f928c1b 100644
--- a/netaddr/ip/sets.py
+++ b/netaddr/ip/sets.py
@@ -627,3 +627,34 @@ class IPSet(object):
         return 'IPSet(%r)' % [str(c) for c in sorted(self._cidrs)]
 
     __str__ = __repr__
+
+    def iscontiguous(self):
+        """
+        Note this method depends on ``iter_cidrs`` being sorted.
+
+        :return: ``True`` if the ``IPSet`` object is contiguous.
+        """
+        previous = self.iter_cidrs()[0][0]
+        for cidr in self.iter_cidrs():
+            if cidr[0] != previous:
+                # This isn't contiguous
+                return False
+            previous = cidr[-1] + 1
+        return True
+
+    def getRange(self):
+        """
+        Get the starting and ending IP of this set, assuming it is 
+        contiguous.
+        Note this method depends on ``iter_cidrs`` being sorted.
+        
+        Raises ``ValueError`` if the set is not contiguous.
+
+        :return: An ``IPRange`` if the IPSet is contiguous.
+        
+        """
+        if self.iscontiguous():
+            cidrs = self.iter_cidrs()
+            return IPRange(cidrs[0][0], cidrs[-1][-1])
+        else:
+            raise ValueError("IPSet is not contiguous")
diff --git a/netaddr/tests/2.x/ip/sets.txt b/netaddr/tests/2.x/ip/sets.txt
index 661882a..b966300 100644
--- a/netaddr/tests/2.x/ip/sets.txt
+++ b/netaddr/tests/2.x/ip/sets.txt
@@ -437,6 +437,28 @@ And we're back to our original address.
 >>> s1
 IPSet(['0.0.0.0/0'])
 
+--------------------------------
+Convert an IP set to an IP Range
+--------------------------------
+Sometimes you may want to convert an IPSet back to an IPRange.
+>>> s1 = IPSet(['10.0.0.0/25', '10.0.0.128/25'])
+
+>>> s1.getRange()
+IPRange('10.0.0.0', '10.0.0.255')
+
+This only works if the IPSet is contiguous
+>>> s1.iscontiguous()
+True
+>>> s1.remove('10.0.0.16')
+>>> s1
+IPSet(['10.0.0.0/28', '10.0.0.17/32', '10.0.0.18/31', '10.0.0.20/30', '10.0.0.24/29', '10.0.0.32/27', '10.0.0.64/26', '10.0.0.128/25'])
+>>> s1.iscontiguous()
+False
+>>> s1.getRange()
+Traceback (most recent call last):
+  File "<stdin>", line 1, in <module>
+ValueError: IPSet is not contiguous
+
 ----------------------
 Pickling IPSet objects
 ----------------------
diff --git a/netaddr/tests/3.x/ip/sets.txt b/netaddr/tests/3.x/ip/sets.txt
index 07c2548..4c83de7 100644
--- a/netaddr/tests/3.x/ip/sets.txt
+++ b/netaddr/tests/3.x/ip/sets.txt
@@ -485,3 +485,24 @@ Pickling of IPSet objects
 True
 
 }}}
+
+Convert an IP set to an IP Range                                                
+
+{{{
+
+>>> s1 = IPSet(['10.0.0.0/25', '10.0.0.128/25'])                                 
+>>> s1.getRange()                                                                
+IPRange('10.0.0.0', '10.0.0.255')
+>>> s1.iscontiguous()                                                            
+True
+>>> s1.remove('10.0.0.16')                                                       
+>>> s1                                                                           
+IPSet(['10.0.0.0/28', '10.0.0.17/32', '10.0.0.18/31', '10.0.0.20/30', '10.0.0.24/29', '10.0.0.32/27', '10.0.0.64/26', '10.0.0.128/25'])
+>>> s1.iscontiguous()                                                            
+False
+>>> s1.getRange()
+Traceback (most recent call last):
+    ...
+ValueError: IPSet is not contiguous
+
+}}}