access: move switch config templates back to this repo

Let’s keep it simple. Also editing templates in NetBox is a pain.

filter_plugins/netbox.py

@@ -7,11 +7,26 @@ class FilterModule(object):
 
     def filters(self):
         return {
+            'compact_numlist': self.compact_numlist,
             'iface_real': self.iface_real,
             'iface_peer': self.iface_peer,
             'iface_vlans': self.iface_vlans
         }
 
+    def compact_numlist(self, nums, sort=True, delimiter=',', range_delimiter='-'):
+        '''Transform [1,2,3,5,7,8,9] into "1-3,5,7-9"'''
+        if sort:
+            nums = sorted(nums)
+        i = 0
+        spans = []
+        while i < len(nums):
+            j = i + 1
+            while j < len(nums) and nums[j]-nums[i] == j-i:
+                j += 1
+            spans += [f'{nums[i]}{range_delimiter}{nums[j-1]}' if j > i+1 else f'{nums[i]}']
+            i = j
+        return delimiter.join(spans)
+
     def iface_real(self, interfaces):
         '''Return only non-virtual interfaces'''
         for iface in interfaces: